Technical Field
[0001] The present invention relates to integrated air-conditioning and hot-water-supply
systems that can perform an air-conditioning operation (i.e., cooling operation or
heating operation) and a hot-water-supply operation at the same time, and more specifically,
to an integrated air-conditioning and hot-water-supply system that determines a high-temperature-water
supply state when the condensing temperature becomes higher than or equal to a predetermined
value during a hot-water supply and that suppresses an excessive increase in high
pressure by controlling the condensing temperature of a compressor and the opening
degree of a pressure-reducing mechanism so as to achieve a predetermined hot-water-supply
capacity within a usage range of the compressor.
Background Art
[0002] In the related art, a hot-water-suppliable heat pump system that is equipped with
a refrigerant circuit formed by connecting a hot-water-supply unit (i.e., a water
heater) to a heat source unit (i.e., an outdoor unit) by pipes and that can perform
the hot-water-supply operation is known. When the hot-water-supply temperature becomes
high (e.g., 60 degrees C) in such a hot-water-supply system, the condensing temperature
increases, causing an excessive increase in high pressure. This is a problem in that
it is difficult to ensure a hot-water-supply capacity. For this reason, there have
been efforts to solve this problem (e.g., see Patent Literature 1 and Patent Literature
2).
In a heat-pump bath hot-water-supply device discussed in Patent Literature 1, the
valve opening degree of a pressure-reducing device is controlled in accordance with
a discharge temperature or a discharge pressure as a target. The operation efficiency
is set in accordance with a discharge temperature or a discharge pressure that has
a maximum value relative to the valve opening degree of the pressure-reducing device
and that corresponds to the maximum operation efficiency as a target control value.
By changing the target control value in accordance with a bathtub temperature, a boiling
temperature, a water-side inlet temperature, and a compressor frequency, high operation
efficiency can be achieved even when the bathtub temperature, the boiling temperature,
the water-side inlet temperature, and the compressor frequency change.
[0003] In a heat-pump hot-water-supply device discussed in Patent Literature 2, the discharge
pressure is monitored during the hot-water-supply operation, and discharge-pressure
control is performed on an expansion valve when the discharge pressure increases,
so that the operation can be continuously performed without the discharge pressure
exceeding the usage range of the compressor.
Citation List
Patent Literature
[0004]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2004-53118
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2005-98530
Summary of Invention
Technical Problem
[0005] In the heat-pump bath hot-water-supply device discussed in Patent Literature 1, the
pressure-reducing device is controlled in accordance with the discharge temperature
or the discharge pressure corresponding to the maximum operation efficiency. However,
in the case where a high-temperature-water supply is performed and the requested hot-water-supply
capacity and the compressor frequency are high, the control is performed based on
the operation efficiency regardless of an increase in the discharge pressure of the
pressure-reducing device. This causes the discharge pressure to increase, possibly
resulting in an excessive increase in the condensing temperature.
[0006] In the heat-pump hot-water-supply device discussed in Patent Literature 2, in the
case where the high-temperature-water supply is performed and the requested hot-water-supply
capacity and the compressor frequency are high, an increase in high pressure sometimes
cannot be suppressed by simply controlling the pressure-reducing device, resulting
in an excessive increase in the condensing temperature.
[0007] Furthermore, in an integrated air-conditioning and hot-water-supply system that is
equipped with a refrigerant circuit formed by connecting a use-side unit (i.e., an
indoor unit) by pipes in addition to a hot-water-supply unit and that can perform
the air-conditioning operation and the hot-water-supply operation at the same time,
if there are an air conditioning load and a high-temperature-water-supply request
at the same time during the high-temperature-water supply, an operation method that
satisfies both of them needs to be established.
[0008] In the present invention, when the condensing temperature becomes higher than or
equal to a predetermined value during the hot-water supply, a high-temperature-water
supply state is determined, condensing-temperature control is performed on a compressor,
and opening-degree control is performed on a pressure-reducing mechanism. Accordingly,
an integrated air-conditioning and hot-water-supply system that can suppress an excessive
increase in condensing temperature and can ensure a hot-water-supply capacity within
a usage range of a compressor during the high-temperature-water supply.
Solution to Problem
[0009] A refrigeration cycle apparatus according to the present invention includes a refrigeration
cycle mechanism having a compressor whose operating frequency is controllable, a first
radiator, a first pressure-reducing mechanism whose opening degree is controllable,
and a first evaporator, and in which a refrigerant sequentially circulates through
the compressor, the first radiator, the first pressure-reducing mechanism, and the
first evaporator; a high-pressure sensor that detects a high pressure between a discharge
side of the compressor and a liquid side of the first pressure-reducing mechanism;
and a controller that calculates a condensing temperature of the first radiator based
on the high pressure detected by the high-pressure sensor. When the calculated condensing
temperature of the first radiator is higher than or equal to a preset target condensing-temperature
value, the controller performs condensing-temperature control for controlling the
operating frequency of the compressor based on a difference between the calculated
condensing temperature and the target condensing-temperature value, and performs opening-degree
control for controlling the opening degree of the first pressure-reducing mechanism
concurrently with the condensing-temperature control based on a difference between
a current opening degree of the first pressure-reducing mechanism and a preset target
opening-degree value.
Advantageous Effects of Invention
[0010] The present invention can provide a refrigeration cycle apparatus that can suppress
an excessive increase in condensing temperature and can ensure a hot-water-supply
capacity within a usage range of a compressor during the high-temperature-water supply.
Brief Description of Drawings
[0011]
[Fig. 1] Fig. 1 illustrates the configuration of an integrated air-conditioning and
hot-water-supply system 100 according to Embodiment 1.
[Fig. 2] Fig. 2 schematically illustrates the flow of water from a hot-water-supply
unit 304 to a hot-water-supply tank 305 in Embodiment 1.
[Fig. 3] Fig. 3 schematically illustrates a controller 110 in Embodiment 1.
[Fig. 4] Fig. 4 illustrates an operation of four-way valves relative to operation
modes in Embodiment 1.
[Fig. 5] Fig. 5 illustrates a method for determining a target evaporating-temperature
value from a maximum cooled-room temperature difference in compressor control in Embodiment
1.
[Fig. 6] Fig. 6 illustrates a method for determining a target condensing-temperature
value from a maximum heated-room temperature difference in compressor control in Embodiment
1.
[Fig. 7] Fig. 7 illustrates the relationships among a target opening degree, a hot-water-supply
capacity, and operation efficiency in Embodiment 1.
[Fig. 8] Fig. 8 illustrates tests performed when performing control for changing a
target opening-degree value of a hot-water-supply pressure-reducing mechanism in accordance
with a compressor frequency in Embodiment 1.
[Fig. 9] Fig. 9 illustrates the relationship between an outdoor-air temperature and
the target opening-degree value in Embodiment 1.
[Fig. 10] Fig. 10 illustrates the relationships among the hot-water-supply capacity,
an evaporating capacity, and a compressor input in Embodiment 1.
[Fig. 11] Fig. 11 illustrates the contents of tests performed at a development stage
when performing control for changing the target opening-degree value in accordance
with the hot-water-supply capacity in Embodiment 1.
[Fig. 12] Fig. 12 is a flowchart illustrating the flow for determining whether a high-temperature-water
supply is to be performed or a normal hot-water supply is to be performed in Embodiment
1.
[Fig. 13] Fig. 13 is a flowchart illustrating an operation method during a high-temperature-water
supply in a simultaneous heating and hot-water-supply operation in Embodiment 1.
[Fig. 14] Fig. 14 is a flowchart illustrating an operation method during a high-temperature-water
supply in a simultaneous cooling and hot-water-supply operation in Embodiment 1.
Description of Embodiments
Embodiment 1
[0012] Embodiment 1 will be described below with reference to Figs. 1 to 14.
Fig. 1 is a refrigerant circuit configuration diagram of an integrated air-conditioning
and hot-water-supply system 100 (refrigeration cycle apparatus) according to Embodiment
1. In the following figures including Fig. 1, the dimensional relationships among
components may sometimes differ from actual dimensional relationships. Furthermore,
when a symbol used in a numerical expression first appears in this specification,
the unit of the symbol will be written in parenthesis []. If a symbol is dimensionless
(i.e., has no units), the unit will be expressed as [-].
[0013] Fig. 2 schematically illustrates the flow of water from a hot-water-supply unit 304
to a hot-water-supply tank 305 in the integrated air-conditioning and hot-water-supply
system 100.
Fig. 3 schematically illustrates various kinds of sensors in the integrated air-conditioning
and hot-water-supply system 100, and a measuring unit 101, a calculating unit 102,
a control unit 103, and a storage unit 104 in a controller 110. The configuration
of the integrated air-conditioning and hot-water-supply system 100 will be described
below with reference to Figs. 1 to 3. The integrated air-conditioning and hot-water-supply
system 100 is a triple-pipe multisystem integrated air-conditioning and hot-water-supply
system that performs a vapor-compression refrigeration cycle operation so as to simultaneously
perform a cooling operation or heating operation selected in a use-side unit and a
hot-water-supply operation in a hot-water-supply unit. The integrated air-conditioning
and hot-water-supply system 100 is an integrated air-conditioning and hot-water-supply
system that can ensure a hot-water-supply capacity by suppressing an excessive increase
in high pressure during a supply of high-temperature water when the hot-water-supply
operation is performed in the hot-water-supply unit. Fig. 1 illustrates the refrigerant
circuit configuration, and Fig. 2 illustrates a water circuit configuration from the
hot-water-supply unit 304 to the hot-water-supply tank 305.
System Configuration
[0014] The integrated air-conditioning and hot-water-supply system 100 has a heat source
unit 301, a branch unit 302, use-side units 303a and 303b, the hot-water-supply unit
304, and the hot-water-supply tank 305. The heat source unit 301 and the branch unit
302 are connected by a liquid extension pipe 6 serving as a refrigerant pipe and a
gas extension pipe 12 serving as a refrigerant pipe. The hot-water-supply unit 304
has one end connected to the heat source unit 301 via a hot-water-supply gas extension
pipe 15 serving as a refrigerant pipe and another end connected to the branch unit
302 via a hot-water-supply liquid pipe 18 serving as a refrigerant pipe. The use-side
units 303a and 303b and the branch unit 302 are connected by indoor gas pipes 11a
and 11 b serving as refrigerant pipes and indoor liquid pipes 8a and 8b serving as
refrigerant pipes. The hot-water-supply tank 305 and the hot-water-supply unit 304
are connected by an upstream water pipe 20 serving as a water pipe and a downstream
water pipe 21 serving as a water pipe.
[0015] Although one heat source unit, two use-side units, one hot-water-supply unit, and
one hot-water-supply tank 305 are connected as an example in Embodiment 1, the configuration
is not limited to this and the numbers thereof may be more than or fewer than those
shown. Furthermore, although a refrigerant used in the integrated air-conditioning
and hot-water-supply system 100 is R410A, the refrigerant used in the integrated air-conditioning
and hot-water-supply system 100 is not limited to this kind of refrigerant. Other
alternatives include, for example, an HFC (hydrofluorocarbon) refrigerant, such as
R407C or R404A, an HCFC (hydrochlorofluorocarbon) refrigerant, such as R22 or R134a,
and a refrigerant that operates at a critical pressure or higher, such as CO
2.
[0016] As shown in Fig. 1, the integrated air-conditioning and hot-water-supply system 100
includes the controller 110. The controller 110 includes the measuring unit 101, the
calculating unit 102, the control unit 103, and the storage unit 104.
Control to be described below is entirely performed by the controller 110. Although
the controller 110 is disposed in the heat source unit 301 in Fig. 1, this is only
an example. The position where the controller 110 is disposed is not limited.
Operation Modes of Heat Source Unit 301
[0017] Operation modes that can be performed by the integrated air-conditioning and hot-water-supply
system 100 will be briefly described. In the integrated air-conditioning and hot-water-supply
system 100, an operation mode of the heat source unit 301 is determined based on whether
there are a hot-water-supply load in the connected hot-water-supply unit 304 and cooling
loads or heating loads in the use-side units 303a and 303b. The integrated air-conditioning
and hot-water-supply system 100 is capable of performing the following five operation
modes, which includes
a cooling operation mode A,
a heating operation mode B,
a hot-water-supply operation mode C,
a simultaneous heating and hot-water-supply operation mode D, and
a simultaneous cooling and hot-water-supply operation mode E.
[0018]
- (1) The cooling operation mode A is an operation mode of the heat source unit 301
when there is no hot-water-supply request signal (also referred to as "hot-water-supply
request") and the cooling operation is performed by the use-side units 303a and 303b.
- (2) The heating operation mode B is an operation mode of the heat source unit 301
when there is no hot-water-supply request and the heating operation is performed by
the use-side units 303a and 303b.
- (3) The hot-water-supply operation mode C is an operation mode of the heat source
unit 301 when there is no air conditioning load and the hot-water-supply operation
is performed by the hot-water-supply unit 304.
- (4) The simultaneous heating and hot-water-supply operation mode D is an operation
mode of the heat source unit 301 when the heating operation by the use-side units
303a and 303b and the hot-water-supply operation by the hot-water-supply unit 304
are simultaneously performed.
- (5) The simultaneous cooling and hot-water-supply operation mode E is an operation
mode of the heat source unit 301 when the cooling operation by the use-side units
303a and 303b and the hot-water-supply operation by the hot-water-supply unit 304
are simultaneously performed.
Use-Side Units 303a and 303b
[0019] The use-side units 303a and 303b are connected to the heat source unit 301 via the
branch unit 302. The use-side units 303a and 303b are installed in areas (e.g., by
being concealed in or suspended from a ceiling indoors or being hung on a wall) where
the units can blow conditioned air to an air conditioning target region. The use-side
units 303a and 303b are connected to the heat source unit 301 via the branch unit
302, the liquid extension pipe 6, and the gas extension pipe 12, and constitute a
part of the refrigerant circuit.
[0020] The use-side units 303a and 303b each include an indoor-side refrigerant circuit
that constitutes a part of the refrigerant circuit. These indoor-side refrigerant
circuits are constituted by respective indoor heat exchangers 9a and 9b serving as
use-side heat exchangers. Furthermore, the use-side units 303a and 303b are respectively
provided with indoor air-sending devices 10a and 10b for supplying conditioned air,
after having exchanged heat with the refrigerant in the indoor heat exchangers 9a
and 9b, to the air conditioning target region, such as an indoor space.
[0021] The indoor heat exchangers 9a and 9b may each be formed of, for example, a cross-fin-type
fin-and-tube heat exchanger constituted of a heat transfer pipe and multiple fins.
Alternatively, the indoor heat exchangers 9a and 9b may each be formed of a micro-channel
heat exchanger, a shell-and-tube heat exchanger, a heat-pipe heat exchanger, or a
double-pipe heat exchanger. When the operation mode performed by the use-side units
303a and 303b is the cooling operation mode A, the indoor heat exchangers 9a and 9b
function as refrigerant evaporators and cool the air in the air conditioning target
region. When the operation mode is the heating operation mode B, the indoor heat exchangers
9a and 9b function as refrigerant condensers (or radiators) and heat the air in the
air conditioning target region.
[0022] The indoor air-sending devices 10a and 10b have a function of suctioning indoor air
into the use-side units 303a and 303b, making the indoor air exchange heat with the
refrigerant at the indoor heat exchangers 9a and 9b, and then supplying the indoor
air as conditioned air to the air conditioning target region. Specifically, in the
use-side units 303a and 303b, the indoor air taken in by the indoor air-sending devices
10a and 10b and the refrigerant flowing through the indoor heat exchangers 9a and
9b can exchange heat with each other. The indoor air-sending devices 10a and 10b are
capable of adjusting the flow rate of conditioned air to be supplied to the indoor
heat exchangers 9a and 9b and each include a fan, such as a centrifugal fan or a multi-blade
fan, and a motor, such as a DC fan motor, for driving this fan.
[0023] The use-side units 303a and 303b are provided with the following various kinds of
sensors, which include:
- (1) indoor liquid temperature sensors 206a and 206b that are provided at the liquid
side of the indoor heat exchangers 9a and 9b and detect the temperature of a liquid
refrigerant;
- (2) indoor gas temperature sensors 207a and 207b that are provided at the gas side
of the indoor heat exchangers 9a and 9b and detect the temperature of a gas refrigerant;
and
- (3) indoor suction temperature sensors 208a and 208b that are provided at the indoor-air
suction side of the use-side units 303a and 303b and detect the temperature of indoor
air flowing into the units.
[0024] As shown in Fig. 3, the operation of the indoor air-sending devices 10a and 10b is
controlled by the control unit 103 that functions as normal-operation control means
that performs a normal operation including the cooling operation mode A and the heating
operation mode B of the use-side units 303a and 303b.
Hot-Water-Supply Unit 304
[0025] The hot-water-supply unit 304 is connected to the heat source unit 301 via the branch
unit 302. As shown in Fig. 2, the hot-water-supply unit 304 has a function of supplying
hot water to the hot-water-supply tank 305 installed, for example, outdoors and boiling
the water in the hot-water-supply tank 305 by heating the water. A plate-type water
heat exchanger 16 of the hot-water-supply unit 304 includes a connection section 25
(i.e., an inflowing-water-pipe connection section) connected to the downstream water
pipe 21 (i.e., an inflowing water pipe), a connection section 26 (i.e., an outflowing
water pipe connection section) connected to the upstream water pipe 20 (i.e., an outflowing
water pipe), and a water pipe 27 through which water flowing therein from the downstream
water pipe 21 flows out toward the upstream water pipe 20. Furthermore, the hot-water-supply
unit 304 has one end connected to the heat source unit 301 via the hot-water-supply
gas extension pipe 15 and another end connected to the branch unit 302 via the hot-water-supply
liquid pipe 18, and constitutes a part of the refrigerant circuit in the integrated
air-conditioning and hot-water-supply system 100.
[0026] The hot-water-supply unit 304 includes a hot-water-supply-side refrigerant circuit
that constitutes a part of the refrigerant circuit. The hot-water-supply-side refrigerant
circuit has the plate-type water heat exchanger 16 serving as a hot-water-supply-side
heat exchanger as an elemental function. Furthermore, the hot-water-supply unit 304
is provided with a feed pump 17 for supplying hot water, after having exchanged heat
with the refrigerant in the plate-type water heat exchanger 16, to the hot-water-supply
tank 305, etc.
[0027] When the hot-water-supply operation mode C is performed by the hot-water-supply unit
304, the plate-type water heat exchanger 16 functions as a refrigerant condenser and
heats the water to be supplied by the feed pump 17. The feed pump 17 has a function
of supplying the water into the hot-water-supply unit 304, making the water exchange
heat at the plate-type water heat exchanger 16 so as to turn the water into hot water,
and then supplying the hot water into the hot-water-supply tank 305 so as to make
the hot water exchange heat with the water in the hot-water-supply tank 305. Specifically,
in the hot-water-supply unit 304, the water supplied by the feed pump 17 and the refrigerant
flowing through the plate-type water heat exchanger 16 can exchange heat with each
other, and the water supplied by the feed pump 17 and the water in the hot-water-supply
tank 305 can exchange heat with each other. Moreover, the flow rate of water to be
supplied to the plate-type water heat exchanger 16 can be adjusted.
[0028] The hot-water-supply unit 304 is provided with the following various kinds of sensors,
which include:
- (1) a hot-water-supply liquid temperature sensor 209 that is provided at the liquid
side of the plate-type water heat exchanger 16 and detects the temperature of a liquid
refrigerant.
[0029] The operation of the feed pump 17 is controlled by the control unit 103 that functions
as normal-operation control means that performs the normal operation including the
hot-water-supply operation mode C of the hot-water-supply unit 304 (see Fig. 3).
Hot-Water-Supply Tank 305
[0030] The hot-water-supply tank 305 is installed, for example, outdoors and has a function
of storing the hot water boiled by the hot-water-supply unit 304. Furthermore, the
hot-water-supply tank 305 has one end connected to the hot-water-supply unit 304 via
the upstream water pipe 20 and another end connected to the hot-water-supply unit
304 via the downstream water pipe 21, and constitutes a part of a water circuit in
the integrated air-conditioning and hot-water-supply system 100. The hot-water-supply
tank 305 is of a full-water type that makes the hot water flow out of the upper portion
of the tank when the hot water is consumed by the user and that is supplied with water
from the lower portion of the tank in accordance with the consumed amount.
[0031] The water fed by the feed pump 17 in the hot-water-supply unit 304 becomes hot water
by being heated by the refrigerant at the plate-type water heat exchanger 16 and then
travels through the upstream water pipe 20 so as to flow into the hot-water-supply
tank 305. The hot water exchanges heat with the water in the hot-water-supply tank
305 as intermediate water without being mixed with the water in the tank, thereby
turning into cold water. Subsequently, the water flows out of the hot-water-supply
tank 305 and travels through the downstream water pipe 21 so as to flow into the hot-water-supply
unit 304 again. After being fed by the feed pump 17 again, the water turns into hot
water at the plate-type water heat exchanger 16. As a result of this process, the
water is boiled in the hot-water-supply tank 305.
[0032] The method for heating the water in the hot-water-supply tank 305 is not limited
to the intermediate-water-based heat exchange method as in Embodiment 1. As an alternative
heating method, the water in the hot-water-supply tank 305 may flow directly into
a pipe, turn into hot water by exchanging heat at the plate-type water heat exchanger
16, and then return to the hot-water-supply tank 305.
[0033] The hot-water-supply tank 305 is provided with the following various kinds of sensors,
which include:
- (1) a hot-water-supply-tank water temperature sensor 210 that is provided on a side
surface at the lower portion of the hot-water-supply tank 305 and detects the temperature
of the hot water in the tank.
Heat Source Unit 301
[0034] The heat source unit 301 is installed, for example, outdoors and is connected to
the use-side units 303a and 303b via the liquid extension pipe 6, the gas extension
pipe 12, and the branch unit 302. Moreover, the heat source unit 301 is connected
to the hot-water-supply unit 304 via the hot-water-supply gas extension pipe 15, the
liquid extension pipe 6, and the branch unit 302, and constitutes a part of the refrigerant
circuit in the integrated air-conditioning and hot-water-supply system 100.
[0035] The heat source unit 301 includes an outdoor-side refrigerant circuit that constitutes
a part of the refrigerant circuit. As elemental devices, the outdoor-side refrigerant
circuit has a compressor 1 that compresses the refrigerant, two four-way valves (i.e.,
a first four-way valve 2 and a second four-way valve 13) for switching the flowing
direction of the refrigerant in accordance with the outdoor operation mode, an outdoor
heat exchanger 3 as a heat-source-side heat exchanger, and an accumulator 14 for retaining
an excess refrigerant. Furthermore, the heat source unit 301 is constituted of an
outdoor air-sending device 4 for supplying air to the outdoor heat exchanger 3 and
an outdoor pressure-reducing mechanism 5 as a heat-source-side pressure-reducing mechanism
for controlling the distributive flow rate of the refrigerant.
[0036] The compressor 1 suctions the refrigerant and compresses this refrigerant to a high-temperature
high-pressure state. The compressor 1 equipped in Embodiment 1 is capable of adjusting
the operation capacity and is, for example, a positive-displacement compressor that
is driven by a motor (not shown) controlled by an inverter. Although only a single
compressor 1 is shown as an example in Embodiment 1, the configuration is not limited
to this, and two or more compressors 1 may be connected in parallel to each other
in accordance with, for example, the connected number of use-side units 303a and 303b
and hot-water-supply units 304. Furthermore, a discharge-side pipe connected to the
compressor 1 is bifurcated at an intermediate section of the pipe and has one end
connected to the gas extension pipe 12 via the second four-way valve 13 and another
end connected to the hot-water-supply gas extension pipe 15 via the first four-way
valve 2.
[0037] The first four-way valve 2 and the second four-way valve 13 each function as a flow
switching device that switches the flowing direction of the refrigerant in accordance
with the operation mode of the heat source unit 301.
Fig. 4 illustrates the operational contents of the four-way valves relative to the
operation modes. The terms "solid line" and "dash line" shown in Fig. 4 correspond
to solid lines and dashed lines shown in Fig. 1 that denote the switched statuses
of the first four-way valve 2 and the second four-way valve 13.
[0038] In the cooling operation mode A, the first four-way valve 2 is switched to the "solid
line" state. Specifically, in the cooling operation mode A, in order to make the outdoor
heat exchanger 3 function as a condenser for the refrigerant compressed by the compressor
1, the first four-way valve 2 is switched so as to connect the discharge side of the
compressor 1 to the gas side of the outdoor heat exchanger 3. In the heating operation
mode B, the hot-water-supply operation mode C, the simultaneous heating and hot-water-supply
operation mode D, or the simultaneous cooling and hot-water-supply operation mode
E, the first four-way valve 2 is switched to the "dash line" state. Specifically,
in the heating operation mode B, the hot-water-supply operation mode C, the simultaneous
heating and hot-water-supply operation mode D, or the simultaneous cooling and hot-water-supply
operation mode E, in order to make the outdoor heat exchanger 3 function as a refrigerant
evaporator, the first four-way valve 2 is switched so as to connect the discharge
side of the compressor 1 to the gas side of the plate-type water heat exchanger 16
and also to connect the suction side of the compressor 1 to the gas side of the outdoor
heat exchanger 3.
[0039] In the cooling operation mode A, the hot-water-supply operation mode C, or the simultaneous
cooling and hot-water-supply operation mode E, the second four-way valve 13 switched
to the "solid line" state. Specifically, the second four-way valve 13 is switched
so as to connect the suction side of the compressor 1 to the gas side of the indoor
heat exchangers 9a and 9b, such that the indoor heat exchangers 9a and 9b are made
to function as evaporators for the refrigerant compressed by the compressor 1 in the
cooling operation mode A or the simultaneous cooling and hot-water-supply operation
mode E or such that the refrigerant is prevented from flowing to the use-side units
303a and 303b in the hot-water-supply operation mode C. In the heating operation mode
B, the hot-water-supply operation mode C, and the simultaneous heating and hot-water-supply
operation mode D, the second four-way valve 13 is switched to the "dash line" state.
Specifically, in the heating operation mode B, the hot-water-supply operation mode
C, and the simultaneous heating and hot-water-supply operation mode D, in order to
make the indoor heat exchangers 9a and 9b function as refrigerant condensers, the
second four-way valve 13 is switched so as to connect the discharge side of the compressor
1 to the gas side of the indoor heat exchangers 9a and 9b.
[0040] The outdoor heat exchanger 3 has its gas side connected to the first four-way valve
2 and its liquid side connected to the outdoor pressure-reducing mechanism 5. The
outdoor heat exchanger 3 may be formed of, for example, a cross-fin-type fin-and-tube
heat exchanger constituted of a heat transfer pipe and multiple fins. Alternatively,
the outdoor heat exchanger 3 may be formed of a micro-channel heat exchanger, a shell-and-tube
heat exchanger, a heat-pipe heat exchanger, or a double-pipe heat exchanger. In the
cooling operation mode A, the outdoor heat exchanger 3 functions as a refrigerant
condenser and cools the refrigerant. In the heating operation mode B, the hot-water-supply
operation mode C, the simultaneous heating and hot-water-supply operation mode D,
and the simultaneous cooling and hot-water-supply operation mode E, the outdoor heat
exchanger 3 functions as a refrigerant evaporator and heats the refrigerant.
[0041] The outdoor air-sending device 4 has a function of suctioning outdoor air into the
heat source unit 301, making the outdoor air exchange heat at the outdoor heat exchanger
3, and then discharging the air to the outside. Specifically, in the heat source unit
301, the outdoor air taken in by the outdoor air-sending device 4 and the refrigerant
flowing through the outdoor heat exchanger 3 can exchange heat with each other. The
outdoor air-sending device 4 is capable of adjusting the flow rate of air to be supplied
to the outdoor heat exchanger 3 and includes a fan, such as a propeller fan, and a
motor, such as a DC fan motor, for driving this fan.
[0042] The accumulator 14 is provided at the suction side of the compressor 1 and has a
function of retaining the liquid refrigerant to prevent it from flowing back to the
compressor 1 when there is a malfunction in the integrated air-conditioning and hot-water-supply
system 100 or during a transient response of an operational state caused by a change
in operation control.
[0043] The heat source unit 301 is provided with the following various kinds of sensors,
which include:
- (1) a high-pressure sensor 201 that is provided at the discharge side of the compressor
1 and detects a high-pressure side high pressure;
- (2) a discharge temperature sensor 202 that is provided at the discharge side of the
compressor 1 and detects a discharge temperature;
- (3) an outdoor gas temperature sensor 203 that is provided at the gas side of the
outdoor heat exchanger 3 and detects a gas refrigerant temperature;
- (4) an outdoor liquid temperature sensor 204 that is provided at the liquid side of
the outdoor heat exchanger 3 and detects a liquid refrigerant temperature; and
- (5) an outdoor-air temperature sensor 205 that is provided at the outdoor-air suction
side of the heat source unit 301 and detects the temperature of outdoor air flowing
into the unit.
[0044] The operation of each of the compressor 1, the first four-way valve 2, the outdoor
air-sending device 4, the outdoor pressure-reducing mechanism 5, and the second four-way
valve 13 is controlled by the control unit 103 that functions as normal-operation
control means that performs the normal operation including the cooling operation mode
A, the heating operation mode B, the hot-water-supply operation mode C, the simultaneous
heating and hot-water-supply operation mode D, and the simultaneous cooling and hot-water-supply
operation mode C.
Branch Unit 302
[0045] The branch unit 302 is installed, for example, indoors, is connected to the heat
source unit 301 via the liquid extension pipe 6 and the gas extension pipe 12, is
connected to the use-side units 303a and 303b via the indoor liquid pipes 8a and 8b
and the indoor gas pipes 11a and 11 b, is connected to the hot-water-supply unit 304
via the hot-water-supply liquid pipe 18, and constitutes a part of the refrigerant
circuit in the integrated air-conditioning and hot-water-supply system 100. The branch
unit 302 has a function of controlling the flow of the refrigerant in accordance with
a requested operation in the use-side units 303a and 303b and the hot-water-supply
unit 304.
[0046] The branch unit 302 includes a branch refrigerant circuit that constitutes a part
of the refrigerant circuit. As elemental devices, the branch refrigerant circuit has
indoor pressure-reducing mechanisms 7a and 7b as use-side pressure-reducing mechanisms
for controlling the distributive flow rate of the refrigerant, and a hot-water-supply
pressure-reducing mechanism 19 for controlling the distributive flow rate of the refrigerant.
[0047] The indoor pressure-reducing mechanisms 7a and 7b are respectively provided in the
indoor liquid pipes 8a and 8b. The hot-water-supply pressure-reducing mechanism 19
is provided in the hot-water-supply liquid pipe 18 in the branch unit 302. Each of
the indoor pressure-reducing mechanisms 7a and 7b functions as a pressure-reducing
valve and an expansion valve, and reduces the pressure of and expands the refrigerant
flowing through the liquid extension pipe 6 in the cooling operation mode A and reduces
the pressure of and expands the refrigerant flowing through the hot-water-supply pressure-reducing
mechanism 19 in the simultaneous cooling and hot-water-supply operation mode E. In
the heating operation mode B and the simultaneous heating and hot-water-supply operation
mode D, the indoor pressure-reducing mechanisms 7a and 7b reduce the pressure of and
expand the refrigerant flowing through the indoor liquid pipes 8a and 8b. The hot-water-supply
pressure-reducing mechanism 19 functions as a pressure-reducing valve and an expansion
valve and reduces the pressure of and expands the refrigerant flowing through the
hot-water-supply liquid pipe 18 in the hot-water-supply operation mode C and the simultaneous
heating and hot-water-supply operation mode D. The indoor pressure-reducing mechanisms
7a and 7b and the hot-water-supply pressure-reducing mechanism 19 may each be of a
type whose opening degree is variably controllable, such as precise flow control means
using an electronic expansion valve or inexpensive refrigerant flow control means
such as a capillary tube.
[0048] As shown in Fig. 3, the operation of the hot-water-supply pressure-reducing mechanism
19 is controlled by the control unit 103 of the controller 110, which functions as
normal-operation control means that performs the normal operation including the hot-water-supply
operation mode C of the hot-water-supply unit 304. The operation of each of the indoor
pressure-reducing mechanisms 7a and 7b is controlled by the control unit 103 functioning
as normal-operation control means that performs the normal operation including the
cooling operation mode A and the heating operation mode B of the use-side units 303a
and 303b.
Controller 110
[0049] As shown in Fig. 3, the values detected by the various kinds of temperature and pressure
sensors are input to the measuring unit 101 and are processed by the calculating unit
102. Then, based on the processed result of the calculating unit 102, the control
unit 103 controls the compressor 1, the first four-way valve 2, the outdoor air-sending
device 4, the outdoor pressure-reducing mechanism 5, the indoor pressure-reducing
mechanisms 7a and 7b, the indoor air-sending devices 10 and 10b, the second four-way
valve 13, the feed pump 17, and the hot-water-supply pressure-reducing mechanism 19.
Specifically, the overall operation of the integrated air-conditioning and hot-water-supply
system 100 is controlled by the controller 110 equipped with the measuring unit 101,
the calculating unit 102, and the control unit 103. The controller 110 may be constituted
of a microcomputer. Calculation expressions to be described in Embodiment 1 below
are calculated by the calculating unit 102, and the control unit 103 controls each
of the devices, such as the compressor 1, in accordance with the calculation results.
The storage unit 104 stores data to be used in the calculating unit 102 and the calculation
results.
[0050] Specifically, based on commands, such as an operation mode (e.g., a cooling request
signal for requesting the cooling operation of the use-side units 303) received via
a remote controller, a hot-water-supply request signal, to be described below, and
a preset temperature, and information detected by the various sensors, the control
unit 103 performs each operation mode by controlling the following:
the operating frequency of the compressor 1,
the switching of the first four-way valve 2,
the rotation speed (including an on/off operation) of the outdoor air-sending device
4,
the opening degree of the outdoor pressure-reducing mechanism 5,
the opening degrees of the indoor pressure-reducing mechanisms 7a and 7b,
the rotation speeds (including an on/off operation) of the indoor air-sending devices
10a and 10b,
the switching of the second four-way valve 13,
the rotation speed (including an on/off operation) of the feed pump 17, and
the opening degree of the hot-water-supply pressure-reducing mechanism 19.
The measuring unit 101, the calculating unit 102, and the control unit 103 may be
integrally provided or may be provided independently of each other. Furthermore, the
measuring unit 101, the calculating unit 102, and the control unit 103 may be provided
in any one of the units. Moreover, the measuring unit 101, the calculating unit 102,
and the control unit 103 may be provided in each of the units.
Operation Modes
[0051] The integrated air-conditioning and hot-water-supply system 100 controls each of
the devices equipped in the heat source unit 301, the branch unit 302, the use-side
units 303a and 303b, and the hot-water-supply unit 304 in accordance with requested
air conditioning loads of the use-side units 303a and 303b and a requested hot-water-supply
load of the hot-water-supply unit 304. With this control, the integrated air-conditioning
and hot-water-supply system 100 performs the cooling operation mode A, the heating
operation mode B, the hot-water-supply operation mode C, the simultaneous heating
and hot-water-supply operation mode D, or the simultaneous cooling and hot-water-supply
operation mode E.
[0052] The simultaneous cooling and hot-water-supply operation mode E further includes a
"hot-water-supply priority mode" in which the operating frequency of the compressor
1 is controlled in accordance with a hot-water-supply request signal from the hot-water-supply
unit 304 and a "cooling priority mode" in which the operating frequency of the compressor
1 is controlled in accordance with cooling loads of the use-side units 303a and 303b.
The hot-water-supply request signal is output from the hot-water-supply unit 304 when
the temperature of the water stored in the hot-water-supply tank 305 is lower than
a preset hot-water-supply temperature. When the hot-water-supply request signal is
output, the control unit 103 estimates a cooling load and a heating load from a temperature
difference (i.e., an indoor temperature difference) between an indoor suction temperature
and a preset indoor temperature and performs control based on an assumption that the
larger the indoor temperature difference, the larger the cooling load and the heating
load.
Operation
[0053] Specific refrigerant flowing methods and normal control methods in the cooling operation
mode A, the heating operation mode B, the hot-water-supply operation mode C, the simultaneous
heating and hot-water-supply operation mode D, and the simultaneous cooling and hot-water-supply
operation mode E performed by the integrated air-conditioning and hot-water-supply
system 100 will now be described. The operation of each four-way valve in each of
the operation modes is as shown in Fig. 4. For each of the hot-water-supply operation
mode C, the simultaneous heating and hot-water-supply operation mode D, and the simultaneous
cooling and hot-water-supply operation mode E, a control method for high-temperature-water
supply will be described in addition to a normal control method.
Cooling Operation Mode A
[0054] In the cooling operation mode, the hot-water-supply pressure-reducing mechanism 19
is completely closed. In the cooling operation mode A, the first four-way valve 2
is in the solid-line state, meaning that the discharge side of the compressor 1 is
connected to the gas side of the outdoor heat exchanger 3. Furthermore, the second
four-way valve 13 is in the solid-line state, meaning that the suction side of the
compressor 1 is connected to the indoor heat exchangers 9a and 9b via the gas extension
pipe 12.
[0055] While the refrigerant circuit is in this state, the compressor 1, the outdoor air-sending
device 4, and the indoor pressure-reducing mechanisms 7a and 7b are activated. This
causes a low-pressure gas refrigerant to be suctioned into and compressed by the compressor
1, thereby becoming a high-temperature high-pressure gas refrigerant. Subsequently,
the high-temperature high-pressure gas refrigerant travels through the first four-way
valve 2 and flows into the outdoor heat exchanger 3 where the gas refrigerant condenses
by exchanging heat with outdoor air supplied by the outdoor air-sending device 4,
thereby becoming a high-pressure liquid refrigerant. After flowing out of the outdoor
heat exchanger 3, the high-pressure liquid refrigerant flows to the outdoor pressure-reducing
mechanism 5 where the high-pressure liquid refrigerant is reduced in pressure. Subsequently,
the liquid refrigerant travels through the liquid extension pipe 6 and flows into
the branch unit 302. At this time, the outdoor pressure-reducing mechanism 5 is controlled
to a maximum opening degree. The refrigerant flowing into the branch unit 302 is reduced
in pressure by the indoor pressure-reducing mechanisms 7a and 7b so as to become a
low-pressure two-phase gas-liquid refrigerant. Subsequently, the refrigerant flows
out of the branch unit 302 and travels through the indoor liquid pipes 8a and 8b so
as to flow into the use-side units 303a and 303b.
[0056] The refrigerant flowing into the use-side units 303a and 303b flows into the indoor
heat exchangers 9a and 9b where the refrigerant evaporates by exchanging heat with
indoor air supplied by the indoor air-sending devices 10a and 10b, thereby becoming
a low-pressure gas refrigerant. In this case, each of the indoor pressure-reducing
mechanisms 7a and 7b is controlled such that a temperature difference (i.e., a cooled-room
temperature difference) obtained by subtracting a preset temperature from an indoor
suction temperature detected by the indoor suction temperature sensor 208a or 208b
in corresponding use-side unit 303a or 303b is eliminated. Therefore, the flow rate
of refrigerant flowing through the indoor heat exchangers 9a and 9b corresponds to
the cooling load requested in the air-conditioned space where the use-side units 303a
and 303b are installed.
[0057] The refrigerant flowing out of the indoor heat exchangers 9a and 9b flows out of
the use-side units 303a and 303b and then travels through the indoor gas pipes 11a
and 11b and the branch unit 302 so as to flow into the gas extension pipe 12. The
refrigerant then travels through the second four-way valve 13 and passes through the
accumulator 14 so as to be suctioned into the compressor 1 again.
[0058] The operating frequency of the compressor 1 is controlled by the control unit 103
such that the evaporating temperature is made equal to a predetermined value. The
predetermined evaporating-temperature value is the temperature detected by the indoor
liquid temperature sensor 206a or 206b. The predetermined evaporating-temperature
value is determined from a temperature difference (i.e., a cooled-room temperature
difference), which is obtained by subtracting a preset temperature from an indoor
suction temperature detected by the indoor suction temperature sensor 208a or 208b,
in the use-side unit 303a or 303b that has the maximum temperature difference in the
use-side units 303a and 303b.
Fig. 5 illustrates a method for determining a target-evaporating-temperature value
from a maximum cooled-room temperature difference in compressor control. Specifically,
as shown in Fig. 5, a target-evaporating-temperature value in a corresponding range
is set on the basis of a maximum cooled-room temperature difference ΔTje [-]. Target-evaporating-temperature
values A1 to A4 in respective maximum cooled-room temperature difference ranges are
determined from tests, etc. Furthermore, the quantity of air from the outdoor air-sending
device 4 is controlled by the control unit 103 such that the condensing temperature
is made equal to a predetermined value in accordance with the outdoor-air temperature
detected by the outdoor-air temperature sensor 205. The condensing temperature in
this case is a saturation temperature calculated based on the pressure detected by
the high-pressure sensor 201.
Heating Operation Mode B
[0059] In the heating operation mode, the hot-water-supply pressure-reducing mechanism 19
(i.e., a first pressure-reducing mechanism) is completely closed. Therefore, the refrigerant
does not flow to the first four-way valve 2 and the hot-water-supply unit 304. In
the heating operation mode B, the first four-way valve 2 is in the dash-line state,
meaning that the discharge side of the compressor 1 is connected to the gas side of
the plate-type water heat exchanger 16 (i.e., a first radiator) and the suction side
of the compressor 1 is connected to the gas side of the outdoor heat exchanger 3 (i.e.,
a first evaporator). The second four-way valve 13 is in the dash-line state, meaning
that the discharge side of the compressor 1 is connected to the gas side of the indoor
heat exchangers 9a and 9b.
[0060] While the refrigerant circuit is in this state, the compressor 1, the outdoor air-sending
device 4, the indoor air-sending devices 10a and 10b, and the feed pump 17 are activated.
This causes a low-pressure gas refrigerant to be suctioned into and compressed by
the compressor 1, thereby becoming a high-temperature high-pressure gas refrigerant.
Subsequently, the high-temperature high-pressure gas refrigerant flows through the
second four-way valve 13.
[0061] The refrigerant flowing into the second four-way valve 13 flows out of the heat source
unit 301 and travels through the gas extension pipe 12 so as to flow into the branch
unit 302. Subsequently, the refrigerant travels through the indoor gas pipes 11a and
11 b so as to flow into the use-side units 303a and 303b. The refrigerant flowing
into the use-side units 303a and 303b flows into the indoor heat exchangers 9a and
9b where the refrigerant condenses by exchanging heat with indoor air supplied by
the indoor air-sending devices 10a and 10b so as to become a high-pressure liquid
refrigerant, which then flows out of the indoor heat exchangers 9a and 9b. The refrigerant
having heated the indoor air at the indoor heat exchangers 9a and 9b flows out of
the use-side units 303a and 303b and travels through the indoor liquid pipes 8a and
8b so as to flow into the branch unit 302. The refrigerant is then reduced in pressure
by the indoor pressure-reducing mechanisms 7a and 7b, thereby becoming a low-pressure,
two-phase gas-liquid or liquid-phase refrigerant. Subsequently, the refrigerant flows
out of the branch unit 302.
[0062] Each of the indoor pressure-reducing mechanisms 7a and 7b is controlled such that
a temperature difference (i.e., a heated-room temperature difference) obtained by
subtracting a preset indoor temperature from an indoor suction temperature detected
by the indoor suction temperature sensor 208a or 208b in corresponding use-side unit
303a or 303b is eliminated. Therefore, the flow rate of refrigerant flowing through
the indoor heat exchangers 9a and 9b corresponds to the heating load requested in
the air-conditioned space where the use-side units 303a and 303b are installed.
[0063] The refrigerant flowing out of the branch unit 302 travels through the liquid extension
pipe 6, flows into the heat source unit 301, passes through the outdoor pressure-reducing
mechanism 5, and then flows into the outdoor heat exchanger 3. The opening degree
of the outdoor pressure-reducing mechanism 5 is controlled so that it is in a completely
open state. The refrigerant flowing into the outdoor heat exchanger 3 evaporates by
exchanging heat with outdoor air supplied by the outdoor air-sending device 4, thereby
becoming a low-pressure gas refrigerant. This refrigerant flows out of the outdoor
heat exchanger 3, travels through the first four-way valve 2, passes through the accumulator
14, and is then suctioned into the compressor 1 again.
[0064] The operating frequency of the compressor 1 is controlled by the control unit 103
such that the condensing temperature is made equal to a target value. The method for
determining the condensing temperature is the same as that in the cooling operation.
The target condensing-temperature value is determined from a temperature difference
(i.e., a heated-room temperature difference), which is obtained by subtracting a preset
indoor temperature from an indoor suction temperature detected by the indoor suction
temperature sensor 208a or 208b, in the use-side unit 303a or 303b that has the maximum
heated-room temperature difference in the use-side units 303a and 303b.
Fig. 6 illustrates a method for determining a target-condensing-temperature value
from a maximum heated-room temperature difference in compressor control. Specifically,
as shown in Fig. 6, a target-condensing-temperature value in a corresponding range
is set on the basis of a maximum heated-room temperature difference ΔTjc [-]. Target-condensing-temperature
values B1 to B4 in respective maximum heated-room temperature difference ranges are
determined from tests, etc. Furthermore, the quantity of air from the outdoor air-sending
device 4 is controlled by the control unit 103 such that the evaporating temperature
is made equal to a predetermined value in accordance with the outdoor-air temperature
detected by the outdoor-air temperature sensor 205. The evaporating temperature in
this case is determined based on the temperature detected by the outdoor liquid temperature
sensor 204.
Hot-Water-Supply Operation Mode C
[0065] In the hot-water-supply operation mode C, the first four-way valve 2 is in the dash-line
state, meaning that the discharge side of the compressor 1 is connected to the gas
side of the plate-type water heat exchanger 16 and the suction side of the compressor
1 is connected to the gas side of the outdoor heat exchanger 3. The second four-way
valve 13 is in the solid-line state, meaning that the suction side of the compressor
1 is connected to the indoor heat exchangers 9a and 9b via the gas extension pipe
12.
[0066] While the refrigerant circuit is in this state, the compressor 1, the outdoor air-sending
device 4, the indoor air-sending devices 10a and 10b, and the feed pump 17 are activated.
This causes a low-pressure gas refrigerant to be suctioned into and compressed by
the compressor 1, thereby becoming a high-temperature high-pressure gas refrigerant.
Subsequently, the high-temperature high-pressure gas refrigerant flows through the
first four-way valve 2.
[0067] The refrigerant flowing into the first four-way valve 2 flows out of the heat source
unit 301 and travels through the hot-water-supply gas extension pipe 15 so as to flow
into the hot-water-supply unit 304. The refrigerant flowing into the hot-water-supply
unit 304 flows into the plate-type water heat exchanger 16 where the refrigerant condenses
by exchanging heat with water supplied by the feed pump 17 so as to become a high-pressure
liquid refrigerant, which then flows out of the plate-type water heat exchanger 16.
The refrigerant having heated the water at the plate-type water heat exchanger 16
flows out of the hot-water-supply unit 304, travels through the hot-water-supply liquid
pipe 18, flows into the branch unit 302, and is then reduced in pressure by the hot-water-supply
pressure-reducing mechanism 19, thereby becoming a low-pressure two-phase gas-liquid
refrigerant. Subsequently, the refrigerant flows out of the branch unit 302 and flows
into the heat source unit 301 via the liquid extension pipe 6.
[0068] In the hot-water-supply operation mode, the opening degree of the hot-water-supply
pressure-reducing mechanism 19 is controlled by the control unit 103 such that the
degree of subcooling at the liquid side of the plate-type water heat exchanger 16
is made equal to a predetermined value. The degree of subcooling at the liquid side
of the plate-type water heat exchanger 16 is determined by calculating a saturation
temperature (i.e., a calculated condensing temperature) from a pressure (i.e., a high
pressure) detected by the high-pressure sensor 201 (i.e., a high-pressure sensor)
and then subtracting a temperature detected by the hot-water-supply liquid temperature
sensor 209 therefrom. The hot-water-supply pressure-reducing mechanism 19 controls
the flow rate of refrigerant flowing through the plate-type water heat exchanger 16
so that the degree of subcooling of the refrigerant at the liquid side of the plate-type
water heat exchanger 16 is made equal to the predetermined value. Therefore, the high-pressure
liquid refrigerant condensed by the plate-type water heat exchanger 16 turns into
a state with a predetermined degree of subcooling. Accordingly, the flow rate of refrigerant
flowing through the plate-type water heat exchanger 16 corresponds to a hot-water-supply
request according to the usage condition of hot water in a facility where the hot-water-supply
unit 304 is installed.
[0069] The refrigerant flowing out of the branch unit 302 travels through the liquid extension
pipe 6, flows into the heat source unit 301, passes through the outdoor pressure-reducing
mechanism 5, and then flows into the outdoor heat exchanger 3. The opening degree
of the outdoor pressure-reducing mechanism 5 is controlled so that it is in a completely
open state. The refrigerant flowing into the outdoor heat exchanger 3 evaporates by
exchanging heat with outdoor air supplied by the outdoor air-sending device 4, thereby
becoming a low-pressure gas refrigerant. This refrigerant flows out of the outdoor
heat exchanger 3, travels through the first four-way valve 2, passes through the accumulator
14, and is then suctioned into the compressor 1 again.
[0070] The operating frequency of the compressor 1 is controlled to a high value by the
control unit 103. Specifically, in the case of the hot-water-supply operation, the
controller 110 ensures a high hot-water-supply capacity so as to increase the water
temperature in the hot-water-supply tank 305 to a preset hot-water-supply temperature
as quickly as possible in response to a hot-water-supply request signal detected by
the hot-water-supply-tank water temperature sensor 210. Furthermore, the quantity
of air from the outdoor air-sending device 4 is controlled by the control unit 103
such that the evaporating temperature is made equal to a predetermined value in accordance
with the outdoor-air temperature detected by the outdoor-air temperature sensor 205.
The evaporating temperature in this case is the temperature detected by the outdoor
liquid temperature sensor 204.
[0071] If the hot-water-supply temperature is high (e.g., 60 degrees C), the inlet water
temperature (i.e., the temperature of water flowing into the connection section 25)
of the plate-type water heat exchanger 16 also becomes high, causing the condensing
temperature to increase. In this case, if the operating frequency of the compressor
1 is controlled to a high value, the high pressure increases to a value outside an
appropriate operating range of the compressor 1. Therefore, if a condensing temperature
calculated from a detected value of the high-pressure sensor 201 reaches an upper
limit value (e.g., 60 degrees C), condensing-temperature control shown in expressions
(1) and (2) is performed on the compressor 1 so as to prevent the condensing temperature
from increasing.
[0072] [Math. 1]

[0073] [Math. 2]

[0074] In this case, Fm denotes a target operating frequency [Hz] of the compressor 1, F
denotes a current operating frequency [Hz] of the compressor 1, ΔF denotes a change
[Hz] in the operating frequency of the compressor 1, CTm denotes a target condensing-temperature
value [degrees C], CT denotes a calculated condensing temperature [degrees C], and
k
CT,comp denotes gain compensation [-] for a change in the operating frequency of the compressor.
The target condensing-temperature value CTm is, for example, a maximum condensing-temperature
value (e.g., 60 degrees C) allowable in an appropriate usage range of the compressor
1. The condensing temperature CT is a saturation temperature calculated from the pressure
detected by the high-pressure sensor 201. The gain compensation k
CT,comp for a change in the operating frequency of the compressor is set to a value based
on tests or simulation such that the condensing temperature CT does not increase from
the target condensing-temperature value CTm and that the frequency does not decrease
rapidly. Although the high-pressure sensor 201 is provided between the compressor
1 and the first four-way valve 2 in Embodiment 1, the configuration is not limited
to this. The high-pressure sensor 201 may be provided at any position between the
liquid side of the hot-water-supply pressure-reducing mechanism 19 and the discharge
side of the compressor 1, which is located at the high-pressure side of the refrigeration
cycle. If the high-pressure sensor 201 is disposed between the first four-way valve
2 and the liquid side of the hot-water-supply pressure-reducing mechanism 19, an additional
pressure sensor for determining the condensing temperature in the heating operation
mode B is disposed between the compressor 1 and the second four-way valve 13.
[0075] If the calculated condensing temperature CT reaches the target condensing-temperature
value CTm during the high-temperature-water supply, CT becomes higher than CTm. In
that case, the operating frequency of the compressor 1 is decreased in accordance
with expressions (1) and (2), whereby the condensing temperature CT can be prevented
from being higher than the target condensing-temperature value CTm. When the operating
frequency of the compressor 1 decreases, the hot-water-supply capacity decreases.
In order to adjust the amount of decrease in the hot-water-supply capacity, pressure-reducing-mechanism
opening-degree control is performed so that a predetermined hot-water-supply capacity
can be ensured. In Embodiment 1, the opening degree of the hot-water-supply pressure-reducing
mechanism 19 is controlled. Specifically, the opening degree of the hot-water-supply
pressure-reducing mechanism 19 is controlled in accordance with expressions (3) and
(4) so that the predetermined hot-water-supply capacity can be ensured.
[0076] [Math. 3]

[0077] [Math. 4]

[0078] In this case, S
j denotes an opening degree [pulse] of the pressure-reducing mechanism after changing
the opening degree thereof, S
j-1 denotes a current opening degree [pulse] of the pressure-reducing mechanism, ΔS
j denotes a change [pulse] in the opening degree of the pressure-reducing mechanism,
and S
jm denotes a target opening degree [pulse] of the pressure-reducing mechanism (sometimes
referred to as "target pressure-reducing-mechanism opening-degree value").
[0079] The target opening degree S
jm [pulse] of the pressure-reducing mechanism can be determined at the development
stage in the following manner.
Fig. 7 illustrates the relationship between the hot-water-supply capacity and the
operation efficiency. Fig. 7(a) illustrates the hot-water-supply capacity of the plate-type
water heat exchanger 16 relative to the opening degree of the hot-water-supply pressure-reducing
mechanism 19. The abscissa axis denotes the opening degree of the hot-water-supply
pressure-reducing mechanism 19, whereas the ordinate axis denotes a target hot-water-supply
capacity value of the plate-type water heat exchanger 16. Fig. 7(b) illustrates the
operation efficiency (COP) relative to the opening degree of the hot-water-supply
pressure-reducing mechanism 19. The abscissa axis denotes the opening degree of the
hot-water-supply pressure-reducing mechanism 19, whereas the ordinate axis denotes
the operation efficiency. When the inlet water temperature during high-temperature-water
supply increases and condensing-temperature control is to be performed on the compressor
1, the hot-water-supply capacity of the plate-type water heat exchanger 16 and the
operation efficiency (COP) change as shown in Figs. 7(a) and 7(b) relative to the
opening degree of the hot-water-supply pressure-reducing mechanism 19. Because the
operating frequency of the compressor 1 becomes higher as the opening degree of the
hot-water-supply pressure-reducing mechanism 19 increases, the hot-water-supply capacity
increases. In contrast, the operation efficiency decreases. The target opening degree
S
jm of the pressure-reducing mechanism can be set based on Fig. 7 as an opening degree
that achieves a minimum-required hot-water-supply capacity to be ensured. Specifically,
the target opening-degree value is set in correspondence with a target value for the
hot-water-supply capacity (i.e., heat-radiation capacity) of the plate-type water
heat exchanger 16 (i.e., first radiator). The target opening degree S
jm of the pressure-reducing mechanism is determined based on tests or simulation at
the development stage. Furthermore, as the hot-water-supply temperature becomes higher
and the inlet water temperature increases (i.e., as CT increases when CT>CTm), the
operating frequency of the compressor 1 is decreased by performing the condensing-temperature
control (i.e., expressions (1) and (2)) on the compressor 1, causing the hot-water-supply
capacity to decrease. Therefore, the target opening degree is determined when the
inlet water temperature is at the maximum. The inlet water temperature is estimated
such that, for example, when the maximum value of the hot-water-supply temperature
is 60 degrees C and the hot-water-supply capacity is a rated hot-water-supply capacity,
the amount of flowing water causes the temperature difference between the inlet water
temperature and the outlet water temperature of the plate-type water heat exchanger
16 to be 5 degrees C. In this case, since the hot-water-supply temperature is 60 degrees
C, the outlet water temperature is 60 degrees C and the inlet water temperature is
55 degrees C. In other words, the maximum inlet water temperature is 55 degrees C.
Because the hot-water-supply capacity increases as the inlet water temperature decreases,
the minimum-required hot-water-supply capacity (i.e., the heat-radiation capacity
of the plate-type water heat exchanger 16) can be ensured by determining the target
opening degree when the inlet water temperature is at the maximum. Furthermore, it
is obvious from Fig. 7 that, by lowering the target hot-water-supply capacity and
lowering the target opening degree S
jm, the operation efficiency can be increased.
The target hot-water-supply capacity value of the plate-type water heat exchanger
16 may be set in correspondence with an upper limit value in design for the inlet
water temperature of the water flowing into the water pipe of the plate-type water
heat exchanger 16 from the downstream water pipe 21.
[0080] When an operation is actually performed with the target opening degree S
jm of the pressure-reducing mechanism described above, the condensing-temperature control
is performed on the compressor 1, and the operation is performed with the target opening
degree S
jm of the pressure-reducing mechanism as a fixed value regardless of the operating
frequency of the compressor 1. Therefore, the minimum-required hot-water-supply capacity
can be ensured when the inlet water temperature is 55 degrees C, and the operating
frequency of the compressor is increased when the inlet water temperature is low at
54 degrees C or 53 degrees C. Because the hot-water-supply capacity increases in proportion
to the operating frequency of the compressor, the hot-water-supply capacity is excessive
when the inlet water temperature is low, leading to reduced operating efficiency even
though the time required for completing the hot-water-supply operation can be shortened.
If the minimum-required hot-water-supply capacity can be ensured, it is desirable
that the hot-water-supply operation be performed at the highest possible operation
efficiency. Therefore, when the inlet water temperature is low at 54 degrees C or
53 degrees C, the opening degree of the hot-water-supply pressure-reducing mechanism
19 may be reduced to suppress an excessive hot-water-supply capacity, so that the
minimum-required hot-water-supply capacity can be ensured. Reducing the opening degree
of the hot-water-supply pressure-reducing mechanism 19 causes a pressure difference
in the hot-water-supply pressure-reducing mechanism 19 to increase and the condensing
temperature to increase, resulting in a lower operating frequency of the compressor
1.
[0081] Fig. 8 illustrates tests performed when performing control for changing the target
opening-degree value of the hot-water-supply pressure-reducing mechanism in accordance
with the frequency of the compressor. The contents of the tests are shown in Fig.
8 for explaining how the control is performed in detail. For determining the target
opening degree of the pressure-reducing mechanism at the development stage mentioned
above, the tests are performed when the inlet water temperature is at the maximum
at 55 degrees C and also when the inlet water temperature is 54 degrees C and 53 degrees
C, and target opening degrees S
jm of the pressure-reducing mechanism that achieve the minimum-required hot-water-supply
capacity to be ensured when the condensing-temperature control is performed on the
compressor 1 (the target condensing temperature is set to, for example, 60 degrees
C) are determined. In this case, a compressor frequency F is also recorded, and a
function f(F) of the target opening degree S
jm of the pressure-reducing mechanism relative to the compressor frequency F is created
from a point obtained from each test. The function of the target opening degree S
jm of the pressure-reducing mechanism can be obtained with higher accuracy by increasing
the number of tested inlet-water-temperature points. Furthermore, because the operating
frequency of the compressor 1 becomes higher and the refrigerant flow rate increases
as the inlet water temperature decreases, the target opening degree S
jm of the pressure-reducing mechanism also increases. In the actual operation, when
the condensing-temperature control is performed on the compressor 1, the target opening
degree S
jm of the pressure-reducing mechanism is determined from the function f(F) shown in
expression (5), which is created at the development stage. The controller 110 stores
the following expression (5) in the storage unit 104 as frequency/opening-degree correspondence
information.
[0082] [Math. 5]

[0083] By performing the operation in this manner, high operating efficiency can be achieved
while the minimum-required hot-water-supply capacity is ensured.
[0084] Fig. 9 illustrates the relationship between the outdoor-air temperature and the target
opening-degree value. As shown in Fig. 9, since the pressure at the low-pressure side
increases and the pressure at the high-pressure side increases as the outdoor-air
temperature increases, the operating frequency of the compressor 1 decreases, causing
the target opening-degree value S
jm for ensuring the hot-water-supply capacity to increase. By changing the target opening-degree
value S
jm in accordance with the outdoor-air temperature, a constant hot-water-supply capacity
can also be ensured relative to a change in the outdoor-air temperature, such as an
increase in the outdoor-air temperature.
The controller 110 stores the relationship between the outdoor-air temperature and
the target opening-degree value shown in Fig. 9 in the storage unit 104 as outdoor-air-temperature/opening-degree
correspondence information. When the condensing-temperature control and the opening-degree
control are concurrently performed, the control unit 103 of the controller 110 refers
to the outdoor-air-temperature/opening-degree correspondence information so as to
identify a target opening-degree value corresponding to an outdoor-air temperature
detected by the outdoor-air temperature sensor 205 from the outdoor-air-temperature/opening-degree
correspondence information, and uses the identified target opening-degree value as
a target opening-degree value in the opening-degree control.
[0085] For determining the target opening degree S
jm of the pressure-reducing mechanism, a target opening degree is determined from tests
performed at the development stage so as to achieve a constant hot-water-supply capacity.
However, because there are individual differences among pressure-reducing mechanisms
in actuality, a constant hot-water-supply capacity is sometimes not achieved even
if the same pressure-reducing mechanism is used. The following configuration can be
used to solve this problem. By determining the hot-water-supply capacity directly
from the operational state of the actual system in operation and setting a target
opening degree of the pressure-reducing mechanism that can at least ensure a "target
constant hot-water-supply capacity" by using the determined hot-water-supply capacity,
variations in hot-water-supply capacity caused by individual differences among pressure-reducing
mechanisms or degradation over time can be prevented, thereby preventing an unexpected
decrease in hot-water-supply capacity.
[0086] Fig. 10 illustrates the relationships among a hot-water-supply capacity Qc, an evaporating
capacity Qe, and a compressor input W. The following description relates to a specific
method. A sum of the evaporating capacity of the outdoor heat exchanger 3 and the
input of the compressor 1 is equal to the hot-water-supply capacity of the plate-type
water heat exchanger 16. Therefore, the hot-water-supply capacity is determined by
determining the evaporating capacity of the outdoor heat exchanger 3 and the input
of the compressor 1 (i.e., compressing work done on the refrigerant by the compressor
1). A table showing the evaporating capacity relative to a temperature difference
between the outdoor-air temperature and the evaporating temperature is created based
on tests, and the evaporating capacity of the outdoor heat exchanger 3 is determined
by using the table.
Fig. 11 illustrates the contents of tests performed at the development stage when
performing control for changing the target opening-degree value in accordance with
the hot-water-supply capacity. The contents of the tests are shown in Fig. 11. The
condensing-temperature control is performed on the compressor 1, and the opening degree
of the hot-water-supply pressure-reducing mechanism 19 that can ensure the hot-water-supply
capacity at a maximum inlet water temperature of 55 degrees C is determined. The "difference
between the outdoor-air temperature and the evaporating temperature" and the "evaporating
capacity" of the outdoor heat exchanger 3 at that point are recorded. In Embodiment
1, the evaporating temperature is based on a detected value of the outdoor liquid
temperature sensor 204. Subsequently, in a state where the opening degree is slightly
changed (to, for example, about 50 pulses) from the previously-determined opening
degree of the hot-water-supply pressure-reducing mechanism 19, the "difference between
the outdoor-air temperature and the evaporating temperature" and the evaporating capacity
of the outdoor heat exchanger 3 at that point are recorded. The blanks in Fig. 11
are filled in this manner. By completing the table in Fig. 11 and applying it to the
actual operation, the evaporating capacity can be calculated from the outdoor-air
temperature and the evaporating temperature. If a difference between the outdoor-air
temperature and the evaporating temperature that is not determined in the tests is
detected in the actual operation, the values on the table are linearly-interpolated
so as to determine the evaporating capacity. Specifically, the relationship between
the "difference between the outdoor-air temperature and the evaporating temperature"
and the evaporating capacity obtained in Fig. 11 is input to the controller 110. The
controller 110 interpolates the results of the relationship (three sets thereof in
Fig. 11) between the "difference between the outdoor-air temperature and the evaporating
temperature" and the evaporating capacity and calculates a function of the evaporating
capacity and the "difference between the outdoor-air temperature and the evaporating
temperature".
[0087] The input W [kW] of the compressor 1 can be calculated from the operating frequency
F [Hz] of the compressor 1, the condensing temperature CT [degrees C], and an evaporating
temperature ET [degrees C] by using the following expression (6). The degree of superheat
at the inlet of the compressor is simply set to zero.
[0088] [Math. 6]

[0089] The operating frequency F of the compressor 1 is obtained as operation information.
The condensing temperature CT is obtained as a saturation pressure detected by the
high-pressure sensor 201. The evaporating temperature ET is determined in a manner
similar to how the evaporating capacity is calculated. Accordingly, since the evaporating
capacity Qe [kW] and the input W [kW] of the compressor 1 can be determined, the hot-water-supply
capacity Qc [kW] can be determined from expression (7).
[0090] [Math. 7]

[0091] The target opening degree S
jm of the pressure-reducing mechanism can be determined from the determined hot-water-supply
capacity Qc and a target minimum-required hot-water-supply capacity value Qcm [kW].
[0092] [Math. 8]

[0093] In this case, k
Qc,Sjm denotes gain compensation [-] for a change in the target opening degree of the pressure-reducing
mechanism and is determined from tests or simulation. By determining the hot-water-supply
capacity from the evaporating capacity and the input of the compressor 1 in this manner,
the target opening degree S
jm of the pressure-reducing mechanism is determined. Accordingly, variations in hot-water-supply
capacity caused by individual differences among pressure-reducing mechanisms can be
suppressed, so that the minimum-required hot-water-supply capacity can be ensured
during the high-temperature-water supply in any actual system. Because the target
opening degree S
jm of the pressure-reducing mechanism is calculated by determining the hot-water-supply
capacity by using the outdoor-air temperature in this method, the outdoor-air temperature
compensation shown in Fig. 9 is not necessary.
[0094] This will be described in detail below. The controller 110 receives data of two or
more sets of a temperature difference between the outdoor-air temperature around the
outdoor heat exchanger 3 and the evaporating temperature of the outdoor heat exchanger
3 and the evaporating capacity of the outdoor heat exchanger 3 corresponding to this
temperature difference. Based on the input data, the controller 110 determines a functional
relationship between the temperature difference and the evaporating capacity by interpolation
and refers to the determined functional relationship so as to identify, from the functional
relationship, the evaporating capacity that corresponds to the temperature difference
between the outdoor-air temperature detected by the outdoor-air temperature sensor
205 and the evaporating temperature detected by the outdoor liquid temperature sensor
204. Then, the controller 110 calculates a compressor input W, which indicates the
compressing work done on the refrigerant by the compressor, from the operating frequency
of the compressor 1, the calculated condensing temperature, and the evaporating temperature
detected by the outdoor liquid temperature sensor 204 (expression (6)). Furthermore,
the controller 110 calculates the hot-water-supply capacity Qc of the plate-type water
heat exchanger 16 from the identified evaporating capacity Qe and the calculated compressor
input W (expression (7)). The controller 110 determines a target opening-degree value
in accordance with a difference between the calculated hot-water-supply capacity Qc
and a preliminarily-stored target hot-water-supply-capacity value Qcm, and uses the
determined target opening-degree value as a target opening-degree value in the opening-degree
control (expression (8)).
[0095] Fig. 12 is a flowchart illustrating the flow for determining whether the high-temperature-water
supply is to be performed or the hot-water-supply (i.e., normal hot-water supply)
other than the high-temperature-water-supply is to be performed. First, in step S11,
the controller 110 determines whether the condensing temperature has increased to
a value higher than a predetermined value CTm. The predetermined value CTm for the
condensing temperature is, for example, a maximum value (e.g., 60 degrees C) of an
appropriate usage range of the compressor 1. If the condensing temperature CT has
increased to a value higher than the predetermined value, the process proceeds to
step S12 where the high-temperature-water-supply operation is performed by performing
the condensing-temperature control shown in expressions (1) and (2) on the compressor
1 and performing the opening-degree control shown in expressions (3) and (4) on the
hot-water-supply pressure-reducing mechanism 19. If the condensing temperature CT
is lower than the predetermined value, the process proceeds to step S13 where the
normal hot-water-supply operation is performed by performing normal control on the
compressor 1 and the hot-water-supply pressure-reducing mechanism 19. This reliably
allows for switching to high-temperature-water supply control in response to an increase
in the condensing temperature CT, thereby suppressing an increase in the condensing
temperature.
[0096] With the above process, the hot-water-supply operation is performed in response to
a hot-water-supply request, and condensing-temperature control is performed on the
compressor and opening-degree control is performed on the pressure-reducing mechanism
during the high-temperature-water supply in which the condensing temperature becomes
higher than the predetermined value CTm, thereby suppressing an excessive increase
in high pressure and achieving a predetermined hot-water-supply capacity.
[0097] Although the hot-water-supply pressure-reducing mechanism 19 is used as a pressure-reducing
mechanism whose opening degree is controlled during the high-temperature-water supply
in which the condensing temperature CT becomes higher than or equal to the predetermined
value CTm in Embodiment 1, this is merely an example. The controlled subject is not
limited to the hot-water-supply pressure-reducing mechanism 19, and the opening-degree
control may alternatively be performed on the outdoor pressure-reducing mechanism
5. In this case, similar to how the opening degree of the outdoor pressure-reducing
mechanism 5 is controlled so that it is in a completely open state when the hot-water-supply
pressure-reducing mechanism 19 is used as a pressure-reducing mechanism whose opening
degree is controlled, the opening degree of the hot-water-supply pressure-reducing
mechanism 19 is controlled so that it is in a completely open state.
[0098] Furthermore, although the integrated air-conditioning and hot-water-supply system
100 is described as an example in Embodiment 1, the high-temperature-water-supply
control according to the technology developed in the present invention can also be
applied to the hot-water-supply operation in a hot-water-supply system in which the
heat source unit 301 and the hot-water-supply unit 304 are connected by a refrigerant
communication pipe, specifically, a hot-water-supply system that does not have an
air-conditioning function but is only capable of performing the hot-water-supply operation.
[0099] Furthermore, although an R410A refrigerant whose operating pressure becomes lower
than or equal to the critical pressure is used as the refrigerant in Embodiment 1,
the refrigerant is not limited to an R410A refrigerant and may alternatively be, for
example, a refrigerant, such as a CO
2 refrigerant, whose operating pressure becomes higher than or equal to the critical
pressure (i.e., a refrigerant whose pressure at the high-pressure side, such as the
pressure at the discharge side of the compressor, becomes higher than or equal to
the critical pressure). In this case, when the pressure (high pressure) detected by
the high-pressure sensor 201 of the controller becomes higher than or equal to a predetermined
high pressure (e.g., 14.5 MPaG when a CO
2 refrigerant is used), high-pressure control shown in expressions (9) and (10) is
performed on the compressor 1 so as to prevent the high pressure from increasing.
[0100] [Math. 9]

[0101] [Math. 10]

[0102] In this case, Fm denotes a target operating frequency [Hz] of the compressor 1, F
denotes a current operating frequency [Hz] of the compressor 1, ΔF denotes a change
[Hz] in the operating frequency of the compressor 1, Pm
high denotes a target high-pressure value [MPaG], P
high denotes a calculated condensing temperature [MPaG], and k
P,comp denotes gain compensation [-] for a change in the operating frequency of the compressor.
The target high-pressure value Pm
high is, for example, a maximum high-pressure value (e.g., 14.5 MPaG when a CO
2 refrigerant is used) allowable in the appropriate usage range of the compressor 1.
Furthermore, in order to adjust the amount of decrease in hot-water-supply capacity,
the opening degree of the hot-water-supply pressure-reducing mechanism 19 is controlled
based on expressions (3) and (4) so that a predetermined hot-water-supply capacity
can be ensured. By performing the control in this manner, the technology according
to the present invention can be applied to a refrigerant that operates at the critical
pressure or higher, similar to a refrigerant that operates at the critical pressure
or lower, such as an R410A refrigerant, thereby suppressing an excessive increase
in high pressure during the high-temperature-water supply so as to achieve the predetermined
hot-water-supply capacity.
Simultaneous Heating and Hot-Water-Supply Operation Mode D
[0103] In the simultaneous heating and hot-water-supply operation mode D (i.e., concurrent
heat-radiation operation), the first four-way valve 2 is in the "dash-line" state
in Fig. 4. This means that the discharge side of the compressor 1 is connected to
the gas side of the plate-type water heat exchanger 16, and the suction side of the
compressor 1 is connected to the gas side of the outdoor heat exchanger 3. The second
four-way valve 13 is in the "dash-line" state. This means that the discharge side
of the compressor 1 is connected to the gas side of the indoor heat exchangers 9a
and 9b. Although both the first four-way valve 2 and the second four-way valve 13
are in the "dash-line" state, as in the "heating operation mode", the hot-water-supply
pressure-reducing mechanism 19 is open in the simultaneous heating and hot-water-supply
operation mode D, unlike in the "heating operation mode" in which the hot-water-supply
pressure-reducing mechanism 19 is closed.
[0104] While the refrigerant circuit is in this state, the compressor 1, the outdoor air-sending
device 4, the indoor air-sending devices 10a and 10b, and the feed pump 17 are activated.
This causes a low-pressure gas refrigerant to be suctioned into and compressed by
the compressor 1, thereby becoming a high-temperature high-pressure gas refrigerant.
Subsequently, the high-temperature high-pressure gas refrigerant is distributed so
as to flow through the first four-way valve 2 and the second four-way valve 13.
[0105] The refrigerant flowing into the first four-way valve 2 flows out of the heat source
unit 301 and travels through the hot-water-supply gas extension pipe 15 so as to flow
into the hot-water-supply unit 304. The refrigerant flowing into the hot-water-supply
unit 304 flows into the plate-type water heat exchanger 16 where the refrigerant condenses
by exchanging heat with water supplied by the feed pump 17 so as to become a high-pressure
liquid refrigerant, which then flows out of the plate-type water heat exchanger 16.
The refrigerant having heated the water at the plate-type water heat exchanger 16
flows out of the hot-water-supply unit 304, travels through the hot-water-supply liquid
pipe 18, flows into the branch unit 302, and is then reduced in pressure by the hot-water-supply
pressure-reducing mechanism 19, thereby becoming a low-pressure two-phase gas-liquid
refrigerant. Subsequently, the refrigerant merges with the refrigerant flowing from
the indoor pressure-reducing mechanisms 7a and 7b and flows out of the branch unit
302. A flow path branching from the discharge side of the compressor 1 and extending
through the second four-way valve 13, the indoor heat exchangers 9a and 9b, and the
indoor pressure-reducing mechanisms 7a and 7b serves as a branch flow path relative
to a flow path for the hot-water-supply operation.
[0106] The opening degree of the hot-water-supply pressure-reducing mechanism 19 is controlled
by the control unit 103 such that the degree of subcooling at the liquid side of the
plate-type water heat exchanger 16 is made equal to a predetermined value. The degree
of subcooling at the liquid side of the plate-type water heat exchanger 16 is similar
to that in the hot-water-supply operation. The hot-water-supply pressure-reducing
mechanism 19 controls the flow rate of refrigerant flowing through the plate-type
water heat exchanger 16 so that the degree of subcooling of the refrigerant at the
liquid side of the plate-type water heat exchanger 16 is made equal to the predetermined
value. Therefore, the high-pressure liquid refrigerant condensed by the plate-type
water heat exchanger 16 turns into a state with a predetermined degree of subcooling.
Accordingly, the flow rate of refrigerant flowing through the plate-type water heat
exchanger 16 corresponds to a hot-water-supply request according to the usage condition
of hot water in the facility where the hot-water-supply unit 304 is installed.
[0107] On the other hand, the refrigerant flowing into the second four-way valve 13 flows
out of the heat source unit 301 and travels through the gas extension pipe 12 so as
to flow to the branch unit 302. Subsequently, the refrigerant travels through the
indoor gas pipes 11a and 11b so as to flow into the use-side units 303a and 303b.
The refrigerant flowing into the use-side units 303a and 303b flows into the indoor
heat exchangers 9a and 9b where the refrigerant condenses by exchanging heat with
indoor air supplied by the indoor air-sending devices 10a and 10b so as to become
a high-pressure liquid refrigerant, which then flows out of the indoor heat exchangers
9a and 9b. The refrigerant having heated the indoor air at the indoor heat exchangers
9a and 9b flows out of the use-side units 303a and 303b and travels through the indoor
liquid pipes 8a and 8b so as to flow into the branch unit 302. The refrigerant is
then reduced in pressure by the indoor pressure-reducing mechanisms 7a and 7b, thereby
becoming a low-pressure, two-phase gas-liquid or liquid-phase refrigerant. Subsequently,
the refrigerant flowing out of the indoor pressure-reducing mechanisms 7a and 7b merges
with the refrigerant flowing from the hot-water-supply pressure-reducing mechanism
19 and flows out of the branch unit 302.
[0108] Each of the indoor pressure-reducing mechanisms 7a and 7b is controlled such that
a temperature difference (i.e., a heated-room temperature difference) obtained by
subtracting a preset indoor temperature from an indoor suction temperature detected
by the indoor suction temperature sensor 208a or 208b (i.e., an indoor temperature
sensor) in corresponding use-side unit 303a or 303b is eliminated. Therefore, the
flow rate of refrigerant flowing through the indoor heat exchangers 9a and 9b corresponds
to the heating load requested in the air-conditioned space where the use-side units
303a and 303b are installed.
[0109] The refrigerant flowing out of the branch unit 302 travels through the liquid extension
pipe 6, flows into the heat source unit 301, passes through the outdoor pressure-reducing
mechanism 5, and then flows into the outdoor heat exchanger 3. The opening degree
of the outdoor pressure-reducing mechanism 5 is controlled so that it is in a completely
open state. The refrigerant flowing into the outdoor heat exchanger 3 evaporates by
exchanging heat with outdoor air supplied by the outdoor air-sending device 4, thereby
becoming a low-pressure gas refrigerant. This refrigerant flows out of the outdoor
heat exchanger 3, travels through the first four-way valve 2, passes through the accumulator
14, and is then suctioned into the compressor 1 again.
[0110] Since there is a hot-water-supply request signal detected by the hot-water-supply-tank
water temperature sensor 210, the operating frequency of the compressor 1 is controlled
to a high value by the control unit 103 so that a high hot-water-supply capacity can
be ensured. The quantity of air from the outdoor air-sending device 4 is controlled
by the control unit 103 such that the evaporating temperature is made equal to a predetermined
value in accordance with the outdoor-air temperature detected by the outdoor-air temperature
sensor 205. The evaporating temperature in this case is the temperature detected by
the outdoor liquid temperature sensor 204.
[0111] If the hot-water-supply temperature is a high temperature (e.g., 60 degrees C), the
inlet water temperature of the plate-type water heat exchanger 16 also becomes high,
causing the condensing temperature to increase. Unlike the case of the hot-water-supply
operation, the heating operation is performed in the use-side units 303a and 303b
in the simultaneous heating and hot-water-supply operation mode D. Therefore, even
if the condensing-temperature control shown in expressions (1) and (2) is performed
on the compressor 1 and the opening-degree control shown in expressions (3) and (4)
is performed on the hot-water-supply pressure-reducing mechanism 19, the hot-water-supply
capacity sometimes cannot be ensured, and the opening degree of the hot-water-supply
pressure-reducing mechanism 19 is controlled regardless of the state in the heated
room. Consequently, a heating capacity cannot be ensured in the use-side units 303a
and 303b, possibly resulting in a non-heated state. Therefore, in the case of the
simultaneous heating and hot-water-supply operation, the simultaneous heating and
hot-water-supply operation is stopped if the condensing temperature CT increases to
a value higher than a predetermined value. Then, the controller 110 performs a switching
process for alternately switching between the heating operation and the hot-water-supply
operation so that the heating operation and the hot-water-supply operation are performed.
[0112] Fig. 13 is a flowchart illustrating the flow of an operation method during the high-temperature-water
supply in the simultaneous heating and hot-water-supply operation. Specifically, the
operation is performed in accordance with the flowchart shown in Fig. 13. First, in
step S21, it is determined whether or not the condensing temperature has increased
to a value higher than a predetermined value. Similar to the case of the hot-water-supply
temperature, the predetermined value for the condensing temperature CT is, for example,
a maximum condensing-temperature value (e.g., 60 degrees C) allowable in the appropriate
usage range of the compressor 1. If the condensing temperature CT is lower than or
equal to the predetermined value, normal control is continuously performed in the
simultaneous heating and hot-water-supply operation in step S22. If the condensing
temperature is above the predetermined value, the mode is changed to a heating operation
mode in step S23. In this case, the use-side units 303a and 303b are set in a heating
thermostat OFF state, and the following control is performed for the purpose of changing
to a hot-water-supply operation mode. In the heating operation, the indoor pressure-reducing
mechanisms 7a and 7b are normally controlled so that a "heated-room temperature difference",
which is equal to "indoor suction temperature (detected by indoor suction temperature
sensor) - preset indoor temperature", is eliminated. The indoor pressure-reducing
mechanisms 7a and 7b are controlled so that the "heated-room temperature difference"
is a positive value, such as +1 degree C (i.e., a predetermined positive value) (S23).
Moreover, the operating frequency of the compressor 1 is controlled so that the condensing
temperature CT is made equal to the target value CTm. Normally, the target value CTm
for the condensing temperature is determined from a "heated-room temperature difference"
in the use-side unit 303a or 303b that has the maximum heated-room temperature difference.
However, the target value CTm for the condensing temperature is determined from a
"heated-room temperature difference of -1 degree C" in the use-side unit 303a or 303b
that has the maximum heated-room temperature difference of -1 degree C. By performing
the control in this manner, the "heated-room temperature difference" (i.e., indoor
suction temperature - preset indoor temperature) can be made equal to +1 degree C.
[0113] Subsequently, in step S24, it is determined whether the heated-room temperature difference
is greater than or equal to +1 degree C. If the heated-room temperature difference
is smaller than +1 degree C, the process returns to step S23. If the heated-room temperature
difference is greater than or equal to +1 degree C, the process proceeds to step S25
where the use-side units 303a and 303b are set in a thermostat OFF state and the hot-water-supply
unit 304 is set in a thermostat ON state, thereby commencing the hot-water-supply
operation mode C. Specifically, the simultaneous heating and hot-water-supply operation
mode D is changed to the hot-water-supply operation mode C. In other words, the first
four-way valve 2 and the second four-way valve 13 are set to the hot-water-supply
operation mode C in Fig. 4. This state is a high-temperature-water-supply state since
the condensing temperature CT is higher than or equal to the predetermined value,
and the controller 110 performs the condensing-temperature control on the compressor
1 and the opening-degree control on the hot-water-supply pressure-reducing mechanism
19. In step S26, the controller 110 determines whether the heated-room temperature
difference (i.e., indoor suction temperature - preset indoor temperature) is greater
than or equal to 0 degrees C. If the heated-room temperature difference is smaller
than 0 degrees C, the process returns to step S23 where the controller 110 performs
the heating operation mode B. If the heated-room temperature difference is greater
than or equal to 0 degrees C, the process proceeds to step S27 where the controller
110 determines whether or not there is a hot-water-supply request (i.e., whether the
hot-water supply is completed). If there is a hot-water-supply request, the process
returns to step S25 where the controller 110 continues to perform the hot-water-supply
operation mode C. If there is no hot-water-supply request, the process proceeds to
step S28 where the controller 110 stops the hot-water-supply unit 304 and sets the
use-side units 303a and 303b to a heating thermostat ON state so as to commence the
normal heating operation.
[0114] By performing the above procedure, a constant heating capacity and a constant hot-water-supply
capacity can be ensured when there is a heating load and a hot-water-supply request
at the same time and when the inlet water temperature is high in the high-temperature-water
supply.
Simultaneous Cooling and Hot-Water-Supply Operation Mode E
[0115] In the simultaneous cooling and hot-water-supply operation mode E (i.e., concurrent
heat-absorption and heat-radiation operation), the use-side units 303a and 303b perform
the cooling operation, and the hot-water-supply unit 304 performs the hot-water-supply
operation. As shown in Fig. 4, in the simultaneous cooling and hot-water-supply operation
mode E, the first four-way valve 2 is in the dash-line state, and the second four-way
valve 13 is in the solid-line state. This means that the discharge side of the compressor
1 is connected to the plate-type water heat exchanger 16 via the hot-water-supply
gas extension pipe 15, and the suction side of the compressor 1 is connected to the
gas side of the outdoor heat exchanger 3. The refrigerant flowing out of the plate-type
water heat exchanger 16 travels through the hot-water-supply pressure-reducing mechanism
19 and subsequently diverges therefrom so as to flow into the indoor pressure-reducing
mechanisms 7a and 7b and into the liquid extension pipe 6.
[0116] While the refrigerant circuit is in this state, the compressor 1, the outdoor air-sending
device 4, the indoor air-sending devices 10a and 10b, and the feed pump 17 are activated,
so that a low-pressure gas refrigerant is suctioned into and compressed by the compressor
1, thereby becoming a high-temperature high-pressure gas refrigerant. Subsequently,
the high-temperature high-pressure gas refrigerant flows into the first four-way valve
2.
[0117] The refrigerant flowing into the first four-way valve 2 flows out of the heat source
unit 301 and travels through the hot-water-supply gas extension pipe 15 so as to flow
into the hot-water-supply unit 304. The refrigerant flowing into the hot-water-supply
unit 304 flows into the plate-type water heat exchanger 16 where the refrigerant condenses
by exchanging heat with water supplied by the feed pump 17 so as to become a high-pressure
liquid refrigerant, which then flows out of the plate-type water heat exchanger 16.
The refrigerant having heated the water at the plate-type water heat exchanger 16
flows out of the hot-water-supply unit 304 and travels through the hot-water-supply
liquid pipe 18, so as to flow into the branch unit 302.
[0118] The refrigerant flowing into the branch unit 302 is reduced in pressure by the hot-water-supply
pressure-reducing mechanism 19, thereby becoming an intermediate-pressure, two-phase
gas-liquid or liquid-phase refrigerant. In this case, the hot-water-supply pressure-reducing
mechanism 19 is controlled to a maximum opening degree. Subsequently, the refrigerant
is distributed so as to flow into the liquid extension pipe 6 and into the indoor
pressure-reducing mechanisms 7a and 7b. As shown in Fig. 1, the refrigeration traveling
toward the indoor units diverges at a branch section 28. Furthermore, in Fig. 1, flow
paths constituted by the indoor pressure-reducing mechanisms 7a and 7b (i.e., second
pressure-reducing mechanisms), the indoor heat exchangers 9a and 9b (i.e., second
evaporators), and the second four-way valve 13 constitute heat-absorption branch flow
paths.
[0119] The refrigerant flowing into the indoor pressure-reducing mechanisms 7a and 7b is
reduced in pressure into a low-pressure two-phase gas-liquid state and travels through
the indoor liquid pipes 8a and 8b so as to flow into the use-side units 303a and 303b.
The refrigerant flowing into the use-side units 303a and 303b flows into the indoor
heat exchangers 9a and 9b where the refrigerant evaporates by exchanging heat with
indoor air supplied by the indoor air-sending devices 10a and 10b, thereby becoming
a low-pressure gas refrigerant.
[0120] In this case, each of the indoor pressure-reducing mechanisms 7a and 7b is controlled
such that a temperature difference (i.e., a cooled-room temperature difference) obtained
by subtracting a preset temperature from an indoor suction temperature detected by
the indoor suction temperature sensor 208a or 208b in corresponding use-side unit
303a or 303b is eliminated. Therefore, the flow rate of refrigerant flowing through
the indoor heat exchangers 9a and 9b corresponds to the cooling load requested in
the air-conditioned space where the use-side units 303a and 303b are installed.
[0121] The refrigerant flowing out of the indoor heat exchangers 9a and 9b flows out of
the use-side units 303a and 303b and then travels through the indoor gas pipes 11a
and 11b, the branch unit 302, and the gas extension pipe 12 so as to flow into the
heat source unit 301. The refrigerant flowing into the heat source unit 301 passes
through the second four-way valve 13 and then merges with the refrigerant having passed
through the outdoor heat exchanger 3.
[0122] On the other hand, the refrigerant flowing into the liquid extension pipe 6 flows
into the heat source unit 301 and is reduced in pressure by the outdoor pressure-reducing
mechanism 5, thereby becoming a low-pressure two-phase gas-liquid refrigerant. Subsequently,
the refrigerant flows into the outdoor heat exchanger 3 where the refrigerant evaporates
by exchanging heat with outdoor air supplied by the outdoor air-sending device 4.
Then, the refrigerant travels through the first four-way valve 2 and merges with the
refrigerant having passed through the indoor heat exchangers 9a and 9b. Subsequently,
the refrigerant passes through the accumulator 14 and is suctioned into the compressor
1 again.
[0123] In the case where the simultaneous cooling and hot-water-supply operation mode E
is in the hot-water-supply priority mode, the water temperature in the hot-water-supply
tank 305 is increased to a preset hot-water-supply temperature as quickly as possible
in response to a hot-water-supply request of the hot-water-supply unit 304. Thus,
in order to ensure a high hot-water-supply capacity, the control unit 103 controls
the compressor 1 so as to increase the operating frequency thereof. Therefore, heat
absorption is necessary in the outdoor heat exchanger 3 for achieving an equal cooling
capacity for the cooling loads of the use-side units 303a and 303b. The opening degree
of the outdoor pressure-reducing mechanism 5 is controlled by the control unit 103
such that the degree of superheat at the gas side of the outdoor heat exchanger 3
is made equal to a predetermined value. The degree of superheat at the gas side of
the outdoor heat exchanger 3 is determined by subtracting the temperature detected
by the outdoor liquid temperature sensor 204 from the temperature detected by the
outdoor gas temperature sensor 203. The quantity of air from the outdoor air-sending
device 4 is controlled such that the evaporating temperature is made equal to a predetermined
value.
The evaporating temperature is the temperature detected by the indoor liquid temperature
sensor 206a or 206b. The predetermined evaporating-temperature value is determined
from a temperature difference (i.e., a cooled-room temperature difference), which
is obtained by subtracting a preset temperature from an indoor suction temperature
detected by the indoor suction temperature sensor 208a or 208b, in the use-side unit
303a or 303b that has the maximum heated-room temperature difference in the use-side
units 303a and 303b.
[0124] In the case where the simultaneous cooling and hot-water-supply operation mode E
is the cooling priority mode, the operating frequency of the compressor 1 is controlled
by the control unit 103 such that the evaporating temperature is made equal to a predetermined
value in accordance with the cooling loads of the use-side units 303a and 303b. The
predetermined evaporating-temperature value is determined from a temperature difference
(i.e., a cooled-room temperature difference), which is obtained by subtracting a preset
temperature from an indoor suction temperature detected by the indoor suction temperature
sensor 208a or 208b, in the use-side unit 303a or 303b that has the maximum heated-room
temperature difference in the use-side units 303a and 303b. Because the operating
frequency of the compressor 1 is set in accordance with the cooling loads of the use-side
units 303a and 303b, there is no need to perform heat absorption in the outdoor heat
exchanger 3. Therefore, the outdoor pressure-reducing mechanism 5 is controlled to
a small opening degree by the control unit 103, and the outdoor air-sending device
4 is stopped by the control unit 103.
[0125] In the simultaneous cooling and hot-water-supply operation mode E, the operation
is normally performed in the cooling priority mode and is performed in accordance
with the cooling load so as to achieve a favorable level of comfort inside. However,
if the cooling load is small, the operating frequency of the compressor 1 becomes
low. If this causes the hot-water-supply capacity to be low for a long time, the time
that it takes to complete the hot-water-supply operation increases, causing a shortage
of hot water. In order to prevent such a shortage of hot water, if a hot-water-supply
request is detected continuously for a certain period of time (e.g., two consecutive
hours), the simultaneous cooling and hot-water-supply operation mode E is performed
in the hot-water-supply priority mode so as to prevent the shortage of hot water.
[0126] If the hot-water-supply temperature is a high temperature (e.g., 60 degrees C), the
inlet water temperature of the plate-type water heat exchanger 16 also becomes high,
causing the condensing temperature CT to increase. Unlike the case of the hot-water-supply
operation, the cooling operation is performed in the use-side units 303a and 303b
in the simultaneous cooling and the hot-water-supply operation. Therefore, when the
condensing-temperature control shown in expressions (1) and (2) is performed on the
compressor 1 and the opening-degree control shown in expressions (3) and (4) is performed
on the hot-water-supply pressure-reducing mechanism 19, the operating frequency of
the compressor 1 becomes low in the condensing-temperature control. Thus, a cooling
capacity cannot be ensured in the use-side units 303a and 303b, sometimes resulting
in a "non-cooled" state. Therefore, if the condensing temperature increases to a value
higher than a predetermined value during the simultaneous cooling and hot-water-supply
operation, the simultaneous operation is stopped, and the cooling operation and the
hot-water-supply operation are performed by alternately switching between the cooling
operation and the hot-water-supply operation, as in the simultaneous heating and hot-water-supply
operation.
[0127] Fig. 14 is a flowchart illustrating the flow of an operation method during the high-temperature-water
supply in the simultaneous cooling and hot-water-supply operation mode. Specifically,
the operation is performed in accordance with the flowchart shown in Fig. 14. First,
in step S31, it is determined whether or not the condensing temperature has increased
to a value higher than a predetermined value. Similar to the case of the hot-water-supply
temperature, the predetermined value for the condensing temperature is, for example,
a maximum condensing-temperature value (e.g., 60 degrees C) allowable in the appropriate
usage range of the compressor 1. If the condensing temperature is lower than or equal
to the predetermined value, normal control is continuously performed in the simultaneous
cooling and hot-water-supply operation in step S32. If the condensing temperature
is higher than or equal to the predetermined value, the process proceeds to the cooling
operation mode A in step S33. In this case, the use-side units 303a and 303b are set
in a cooling thermostat OFF state, and the following control is performed for the
purpose of changing to the hot-water-supply operation mode C. In the cooling operation,
the indoor pressure-reducing mechanisms 7a and 7b are normally controlled so that
a "cooled-room temperature difference", which is equal to "indoor suction temperature
(detected by indoor suction temperature sensor) - preset indoor temperature", is eliminated.
The indoor pressure-reducing mechanisms 7a and 7b are controlled so that the cooled-room
temperature difference is a negative value, such as -1 degree C (i.e., a predetermined
negative value). Moreover, the operating frequency of the compressor 1 is controlled
so that the evaporating temperature is made equal to a target value. Normally, the
target value for the evaporating temperature is determined from a cooled-room temperature
difference in the use-side unit 303a or 303b that has the maximum cooled-room temperature
difference in the use-side units 303a and 303b. However, the target evaporating-temperature
value for the operating frequency of the compressor 1 is determined from a cooled-room
temperature difference of +1 degree C in the use-side unit 303a or 303b that has the
maximum heated-room temperature difference of +1 degree C. By performing the control
in this manner, the cooled-room temperature difference can be made equal to -1 degree
C.
[0128] Subsequently, in step S34, it is determined whether the cooled-room temperature difference
is smaller than or equal to -1 degree C. If the cooled-room temperature difference
is not smaller than or equal to -1 degree C, the process returns to step S33. If the
cooled-room temperature difference is smaller than or equal to -1 degree C, the process
proceeds to step S35 where the use-side units 303a and 303b are set in a cooling thermostat
OFF state and the mode is changed to the hot-water-supply operation mode C. In the
hot-water-supply operation mode C, this state is a high-temperature-water-supply state
since the condensing temperature is higher than or equal to the predetermined value,
and the condensing-temperature control is performed on the compressor 1, and the opening-degree
control is performed on the hot-water-supply pressure-reducing mechanism 19. In step
S36, it is determined whether the cooled-room temperature difference is smaller than
or equal to 0 degrees C. If the cooled-room temperature difference is greater than
or equal to 0 degrees C, the process returns to step S33 where the mode is set to
the cooling operation mode A. If the cooled-room temperature difference is smaller
than or equal to 0 degrees C, the process proceeds to step S37 where it is determined
whether or not there is a hot-water-supply request (i.e., whether the hot-water supply
is completed). If there is a hot-water-supply request, the process returns to step
S35 where the hot-water-supply operation mode C is continuously performed. If there
is no hot-water-supply request, the process proceeds to step S38 where the hot-water-supply
unit 304 is stopped and the use-side units 303a and 303b are set to a cooling thermostat
ON state, thereby commencing the normal cooling operation.
[0129] By performing the above procedure, a constant hot-water-supply capacity can be ensured
and the cooling operation can be performed when there is a cooling load and a hot-water-supply
request at the same time and when the inlet water temperature is high in the high-temperature-water
supply.
[0130] With the integrated air-conditioning and hot-water-supply system 100 according to
Embodiment 1, an excessive increase in condensing temperature during the high-temperature-water
supply can be suppressed, and a hot-water-supply capacity can be ensured within a
usage range of the compressor.
[0131] Although the integrated air-conditioning and hot-water-supply system 100 (refrigeration
cycle apparatus) is described in Embodiment 1, the operation of the integrated air-conditioning
and hot-water-supply system 100 can be construed as a refrigeration cycle control
method.
Reference Signs List
[0132] 1: compressor, 2: first four-way valve, 3: outdoor heat exchanger, 4: outdoor air-sending
device, 5: outdoor pressure-reducing mechanism, 6: liquid extension pipe, 7a, 7b:
indoor pressure-reducing mechanism, 8a, 8b : indoor liquid pipe, 9a, 9b: indoor heat
exchanger, 10a, 10b: indoor air-sending device, 11a, 11b: indoor gas pipe, 12: gas
extension pipe, 13: second four-way valve, 14: accumulator, 15: hot-water-supply gas
extension pipe, 16: plate-type water heat exchanger, 17: feed pump, 18: hot-water-supply
liquid pipe, 19: hot-water-supply pressure-reducing mechanism, 20: upstream water
pipe, 21: downstream water pipe, 100: integrated air-conditioning and hot-water-supply
system, 110: controller, 101: measuring unit, 102: calculating unit, 103: control
unit, 104: storage unit, 201: high-pressure sensor, 202: discharge temperature sensor,
203: outdoor gas temperature sensor, 204: outdoor liquid temperature sensor, 205:
outdoor-air temperature sensor, 206a, 206b: indoor liquid temperature sensor, 207a,
207b: indoor gas temperature sensor, 208a, 208b: indoor suction temperature sensor,
209: hot-water-supply liquid temperature sensor, 210: hot-water-supply-tank water
temperature sensor, 301: heat source unit, 302: branch unit, 303a, 303b: use-side
unit, 304: hot-water-supply unit, 305: hot-water-supply tank