[Technical Field]
[0001] The present invention relates to a heat supply system.
[Background Art]
[0002] PTL 1 listed below discloses a heat pump water heater that includes a water heater
circuit in which a refrigerant-water heat exchanger for a heat pump and a heating
device including an electric heater are connected sequentially. This heat pump water
heater includes a first temperature detector that is provided downstream of the refrigerant-water
heat exchanger, and a second temperature detector that is provided downstream of the
heating device. In the heat pump water heater, in a case where the set temperature
of hot water is relatively low, the electric heater of the heating device is brought
into a non-energized state, and the rotation speed of a circulation pump is controlled
using a signal of the first temperature detector such that the temperature of hot
water at the outlet of the refrigerant-water heat exchanger becomes constant. In the
heat pump water heater, in a case where the set temperature of hot water is high,
the electric heater of the heating device is energized, and the rotation speed of
the circulation pump is controlled using a signal of the second temperature detector
such that the temperature of hot water at the outlet of the heating device becomes
constant.
[Citation List]
[Patent Literature]
[0003] [PTL 1] Japanese Patent Application Laid-open No.
H8-14657
[Summary of Invention]
[Technical Problem]
[0004] In cases where the electric heater of the heating device is brought into a non-energized
state in the conventional heat pump water heater described above, there is a possibility
that heat of hot water coming out of the refrigerant-water heat exchanger is removed
while the hot water is passing through the heating.device not generating heat, resulting
in the temperature of the hot water being reduced. As a consequence, the temperature
of supplied hot water may undershoot. In addition, in the case where the length of
a flow path between the refrigerant-water heat exchanger and the heating device is
large, the temperature of hot water may be reduced while the hot water coming out
of the refrigerant-water heat exchanger is flowing to the heating device. As a result,
the temperature of the supplied hot water may undershoot. Further, in the case where
the electric heater of the heating device is turned ON from its OFF state in the heat
pump water heater, the temperature of the supplied hot water may overshoot.
[0005] The present invention has been made in order to solve the above problems. An object
of the present invention is to prevent undershooting and overshooting of the temperature
of a heating medium in a heat supply system that includes a first heating device and
a second heating device.
[Solution to Problem]
[0006] A heat supply system of the invention includes: a pump configured to pump a heating
medium; a first heating device configured to heat the heating medium; a second heating
device configured to heat the heating medium downstream of the first heating device;
and a controller configured to perform a first operation and a second operation sequentially
after activation of the first heating device, in a case where the first heating device
is activated without operating the second heating device. In the first operation,
a temperature of the heating medium downstream of the first heating device and upstream
of the second heating device is controlled so as to converge to a target value. In
the second operation, the temperature of the heating medium downstream of the second
heating device is controlled so as to converge to a target value.
[0007] A heat supply system of the invention includes: a pump configured to pump a heating
medium; a first heating device configured to heat the heating medium; a second heating
device configured to heat the heating medium downstream of the first heating device;
and a controller configured to reduce a heating power of the first heating device
concurrently with or before activation of the second heating device, in a case where
the second heating device is activated in a state in which the first heating device
is operated without operating the second heating device.
[Advantageous Effects of Invention]
[0008] According to the present invention, it becomes possible to prevent the undershooting
and the overshooting of the temperature of the heating medium in the heat supply system
that includes the first heating device and the second heating device.
[Brief Description of Drawings]
[0009]
Fig. 1 is a configuration diagram showing a heat supply system of Embodiment 1 of
the present invention.
Fig. 2 is a block diagram showing a flow of a signal of the heat supply system of
Embodiment 1.
Fig. 3 is a hardware configuration diagram of the heat supply system of Embodiment
1.
Fig. 4 is a flowchart of a routine executed by a controller of the heat supply system
of Embodiment 1.
Fig. 5 is a flowchart showing a second example of a method for determining whether
a temperature condition of a heating medium is stabilized.
Fig. 6 is a flowchart showing a third example of the method for determining whether
the temperature condition of the heating medium is stabilized.
Fig. 7 is a graph showing an example of a change in a detected temperature of each
of a main thermistor and an auxiliary thermistor after an activation of a main heat
source.
Fig. 8 is a graph showing an example of a change in the detected temperature of each
of the main thermistor and the auxiliary thermistor after the activation of the main
heat source.
Fig. 9 is a graph showing an example of the change in the detected temperature of
each of the main thermistor and the auxiliary thermistor after the activation of the
main heat source.
Fig. 10 is a flowchart of a routine executed by a controller of a heat supply system
of Embodiment 2.
Fig. 11 is a graph showing an example of a change in temperatures in a vicinity of
an upstream side and a downstream side of an auxiliary heat source in a case where
the auxiliary heat source is activated in a state in which a main heat source is operated
and the auxiliary heat source is not operated.
Fig. 12 is a graph showing an example of a change in temperatures in the vicinity
of the downstream side and the upstream side of the auxiliary heat source in the case
where the auxiliary heat source is activated in the state in which the main heat source
is operated and the auxiliary heat source is not operated.
Fig. 13 is a flowchart of a routine executed by a controller of a heat supply system
of Embodiment 3.
Fig. 14 is a graph showing an example of a change in temperatures in a vicinity of
a downstream side and an upstream side of an auxiliary heat source in a case where
the auxiliary heat source is activated in a state in which a main heat source is operated
and the auxiliary heat source is not operated.
Fig. 15 is a graph showing an example of a change in the temperatures in the vicinity
of the downstream side and the upstream side of the auxiliary heat source in the case
where the auxiliary heat source is activated in the state in which the main heat source
is operated and the auxiliary heat source is not operated.
[Description of Embodiments]
[0010] Hereinbelow, embodiments of the present invention will be described with reference
to the drawings. Note that common elements in the drawings are denoted by the same
reference numerals, and the duplicate description thereof will be omitted.
Embodiment 1
[0011] Fig. 1 is a configuration diagram showing a heat supply system of Embodiment 1 of
the present invention. A heat supply system 1 of the present embodiment shown in Fig.
1 is a hot water supply indoor-heating system. The heat supply system 1 includes a
first unit 2, a second unit 3, and a controller 100. In the present embodiment, the
first unit 2 is placed outdoors, and the second unit 3 is placed indoors. The second
unit 3 may also be placed outdoors. The first unit 2 and the second unit 3 are connected
via heating medium pipes 4 and 5.
[0012] The first unit 2 includes a first casing in which a main heat source 6 is housed.
The main heat source 6 is an example of a first heating device that heats a liquid
heating medium. As the heating medium, it is possible to use, e.g., water, brine,
and antifreeze solution. The main heat source 6 in the present embodiment is a heat
pump heating device. The main heat source 6 includes a refrigerant circuit. The refrigerant
circuit includes a compressor 7, a high-temperature side heat exchanger 8, a decompression
device 9, and a low-temperature side heat exchanger 10. The main heat source 6 heats
the heating medium by performing an operation of a heat pump cycle (refrigeration
cycle) with the refrigerant circuit. The high-temperature side heat exchanger 8 heats
the heating medium by exchanging heat between the refrigerant compressed by the compressor
7 and the heating medium. The decompression device 9 reduces the pressure of the refrigerant
having passed through the high-temperature side heat exchanger 8. The decompression
device 9 is constituted by, e.g., an expansion valve. The low-temperature side heat
exchanger 10 is an evaporator that evaporates the refrigerant having passed through
the decompression device 9. In the present embodiment, the low-temperature side heat
exchanger 10 exchanges heat between outdoor air and the refrigerant. The main heat
source 6 includes a blower 11 that blows outside air into the low-temperature side
heat exchanger 10. The low-temperature side heat exchanger 10 may exchange heat between
the heat source other than the outside air (e.g., groundwater, wastewater, and solar
heated water) and the refrigerant. The refrigerant is preferably CO
2.
[0013] The compressor 7, the decompression device 9, and the blower 11 are connected to
the controller 100. The controller 100 is capable of controlling the heating power
of the main heat source 6. The heating power denotes an amount of heat per unit time
that the heating medium receives. The controller 100 is capable of controlling the
heating power of the main heat source 6 by, e.g., changing the driving frequency of
the compressor 7 using inverter control. The controller 100 may control the heating
power of the main heat source 6 by changing the opening of the decompression device
9.
[0014] The second unit 3 includes a second casing in which an auxiliary heat source 12 is
housed. The auxiliary heat source 12 is an example of a second heating device that
heats the heating medium downstream of the high-temperature side heat exchanger 8
of the main heat source 6. As the auxiliary heat source 12, it is possible to use,
e.g., an electric heater or a fuel heater. In the case of the fuel heater, the fuel
may be any fuel such as gas, kerosene, heavy oil, and coal. The auxiliary heat source
12 is operated when the heating power of the main heat source 6 is insufficient, and
compensates for the insufficiency of the heating power. An example of the case where
the heating power of the main heat source 6 becomes insufficient includes the case
where the temperature of the medium (outdoor air in the present embodiment) used in
the heat exchange with the refrigerant in the low-temperature side heat exchanger
10 of the main heat source 6 is low.
[0015] In the second unit 3, a hot water tank 13, a hot water supply heat exchanger 14,
a heating medium pump 15, a water pump 16, and a switching valve 17 are further housed.
The auxiliary heat source 12, the heating medium pump 15, the water pump 16, and the
switching valve 17 are connected to the controller 100. The hot water supply heat
exchanger 14 heats water by exchanging heat between the heating medium and water.
The outlet of the heating medium of the hot water supply heat exchanger 14 is connected
to the inlet of the heating medium pump 15. The outlet of the heating medium pump
15 is connected to the inlet of the heating medium of the high-temperature side heat
exchanger 8 in the first unit 2 via the heating medium pipe 4. The outlet of the heating
medium of the high-temperature side heat exchanger 8 is connected to the inlet of
the auxiliary heat source 12 in the second unit 3 via the heating medium pipe 5.
[0016] The switching valve 17 has an A port, a B port, and a C port. The switching valve
17 is capable of switching between a state in which the A port is caused to communicate
with the B port and the C port is closed and a state in which the A port is caused
to communicate with the C port and the B port is closed. The switching valve 17 may
also be capable of switching to a state in which the heating medium flowing in from
the A port is distributed to the B port and the C port. The outlet of the auxiliary
heat source 12 is connected to the A port of the switching valve 17. The B port of
the switching valve 17 is connected to the inlet of the heating medium of the hot
water supply heat exchanger 14.
[0017] Water is stored in the hot water tank 13. In the hot water tank 13, it is possible
to form temperature stratification in which the upper side has high temperature and
the lower side has low temperature due to a difference in the density of water caused
by a difference in temperature. Clean water supplied from a water source 40 such as
water works passes through a water supply pipe 18 and flows into the lower portion
of the hot water tank 13. In a heat accumulating circuit that accumulates heat in
the hot water tank 13, the lower portion of the hot water tank 13 is connected to
the inlet of water of the hot water supply heat exchanger 14, and the outlet of water
of the hot water supply heat exchanger 14 is connected to the upper portion of the
hot water tank 13. The water pump 16 circulates water to the heat accumulating circuit.
A hot water supply pipe 19 is connected to the upper portion of the hot water tank
13. The downstream side of the hot water supply pipe 19 is connected to a hot water
faucet 20 outside the second unit 3. When the hot water faucet 20 is opened, hot water
stored in the hot water tank 13 is supplied to the hot water faucet 20 through the
hot water supply pipe 19. A mixing valve (depiction thereof is omitted) for mixing
hot water and cold water to adjust temperature may be disposed in the middle of the
hot water supply pipe 19.
[0018] An indoor-heating appliance 21 warms indoor air by using heat of the heating medium
supplied from the second unit 3. The C port of the switching valve 17 is connected
to the inlet of the heating medium of the indoor-heating appliance 21 via a heating
medium pipe 22. One end of a heating medium pipe 23 is connected to the outlet of
the heating medium of the indoor-heating appliance 21. The other end of the heating
medium pipe 23 is connected to a flow path between the outlet of the heating medium
of the hot water supply heat exchanger 14 and the inlet of the heating medium pump
15. As the indoor-heating appliance 21, it is possible to use, e.g., a floor heating
panel, a radiator, a panel heater, and a fan convector. A plurality of the indoor-heating
appliances 21 may also be connected between the heating medium pipe 22 and the heating
medium pipe 23. In this case, a method for connecting the plurality of the indoor-heating
appliances 21 may be any of series connection, parallel connection, and a combination
of the series connection and the parallel connection.
[0019] Each of the hot water tank 13, the hot water supply heat exchanger 14, the hot water
faucet 20, and the indoor-heating appliance 21 is an example of a heat use terminal
as a terminal that uses heat supplied by the heat supply system 1. The heat use terminal
may also be a terminal other than the heat use terminals mentioned above. The heat
use terminal may also be a terminal that uses heat by directly discharging a heated
heating medium. The number of the heat use terminals does not need to be plural as
in the present embodiment, and the number thereof may also be one.
[0020] In each of the heating medium pump 15 and the water pump 16, output or rotation speed
thereof is preferably variable. As each of the heating medium pump 15 and the water
pump 16, for example, the pump that includes a pulse width modulation control (PWM
control) type DC motor of which the output or rotation speed can be changed with a
speed command voltage from the controller 100 can be preferably used.
[0021] In the heating medium pipe 5 downstream of the main heat source 6 and upstream of
the auxiliary heat source 12, an auxiliary thermistor 24 is disposed. The auxiliary
thermistor 24 is an example of a first temperature sensor that detects the temperature
of the heating medium downstream of the first heating device (the main heat source
6) and upstream of the second heating device (the auxiliary heat source 12). The auxiliary
thermistor 24 is disposed in the first unit 2. The length of a flow path from the
main heat source 6 to the auxiliary thermistor 24 is preferably shorter than the length
of a flow path from the auxiliary thermistor 24 to the auxiliary heat source 12. The
temperature of the heating medium downstream of the main heat source 6 and upstream
of the auxiliary heat source 12 is hereinafter referred to as an "outlet temperature
of the main heat source 6". The auxiliary thermistor 24 is capable of detecting the
outlet temperature of the main heat source 6.
[0022] In a flow path of the heating medium downstream of the auxiliary heat source 12 and
upstream of the heat use terminal, a main thermistor 25 is disposed. The main thermistor
25 is an example of a second temperature sensor that detects the temperature of the
heating medium downstream of the second heating device (the auxiliary heat source
12). The main thermistor 25 detects the temperature of the heating medium downstream
of the auxiliary heat source 12 and upstream of the switching valve 17. The temperature
of the heating medium downstream of the auxiliary heat source 12 is hereinafter referred
to as a "heating medium supply temperature". The main thermistor 25 is capable of
detecting the heating medium supply temperature.
[0023] In a flow path of the heating medium downstream of the heat use terminal and upstream
of the main heat source 6, a low-temperature thermistor 26 is disposed. The low-temperature
thermistor 26 is an example of a third temperature sensor that detects the temperature
of the heating medium upstream of the first heating device (the main heat source 6).
The low-temperature thermistor 26 is disposed upstream of the heating medium pump
15. The low-temperature thermistor 26 may also be disposed in the heating medium pipe
4 downstream of the heating medium pump 15. A flow rate sensor 27 detects the flow
rate of the heating medium that flows in the main heat source 6 and the auxiliary
heat source 12. In a configuration shown in the drawing, the flow rate sensor 27 is
disposed in the heating medium pipe 4 downstream of the heating medium pump 15. A
room temperature thermistor 28 is an example of a room temperature sensor that detects
the room temperature of a room in which the indoor-heating appliance 21 is disposed.
A plurality of hot water temperature sensors 30a, 30b, and 30c are mounted to the
surface of the hot water tank 13 at intervals in a vertical direction. The controller
100 is capable of calculating, for example, the amount of hot water and the amount
of stored heat in the hot water tank 13 by detecting a temperature distribution in
the vertical direction in the hot water tank 13 using the hot water temperature sensors
30a, 30b, and 30c. In the configuration shown in the drawing, the number of the hot
water temperature sensors is three. However, the number of the hot water temperature
sensors is not limited to three.
[0024] The controller 100 controls the operation of each of the main heat source 6, the
auxiliary heat source 12, the heating medium pump 15, the water pump 16, and the switching
valve 17. In the case where the heating power of the main heat source 6 is insufficient
for the request of the heat use terminal, the controller 100 activates the auxiliary
heat source 12.
[0025] The heat supply system 1 is capable of switching between a heat accumulating operation
and an indoor-heating operation. In the indoor-heating operation, the switching valve
17 is controlled such that the heating medium is circulated to the indoor-heating
appliance 21. In the heat accumulating operation, the switching valve 17 is controlled
such that the heating medium is circulated to the hot water supply heat exchanger
14. In the heat accumulating operation, the water pump 16 is driven, and water of
the hot water tank 13 is circulated to the hot water supply heat exchanger 14. In
the hot water supply heat exchanger 14, water is heated with the heat of the heating
medium. Hot water that comes out of the hot water supply heat exchanger 14 returns
to the hot water tank 13, whereby the heat of the hot water is accumulated in the
hot water tank 13.
[0026] In the present embodiment, the first unit 2 in which the main heat source 6 is housed
and the second unit 3 in which the auxiliary heat source 12 and the hot water tank
13 are housed are configured to be separated from each other. By disposing the auxiliary
thermistor 24 in the first unit 2, it is possible to use the auxiliary thermistor
24 for protection control of the main heat source 6. The main thermistor 25 is capable
of detecting the temperature of the heating medium having passed through the main
heat source 6 and the auxiliary heat source 12, i.e., the heating medium supply temperature.
By disposing the main thermistor 25 in the second unit 3, it is possible to detect
the heating medium supply temperature at a position close to the heat use terminal.
That is, it is possible to accurately detect the temperature of the heating medium
that is supplied to the heat use terminal. As a result, it is possible to control
the temperature of the heating medium supplied to the heat use terminal with high
accuracy. In the case where the second unit 3 is disposed indoors, it is possible
to increase the ambient temperature of the second unit 3 as compared with the case
where the second unit 3 is disposed outdoors, and hence it is possible to improve
thermal insulation performance of the hot water tank 13. In the case where the second
unit 3 is disposed indoors, it is possible to reduce the distance between the auxiliary
heat source 12 and the heat use terminal, and hence it is possible to reduce loss
of heat supplied to the heating medium from the auxiliary heat source 12. In the present
embodiment, the heating medium pump 15, the water pump 16, the auxiliary heat source
12, the hot water tank 13, and the hot water supply heat exchanger 14 are housed in
the second unit 3. However, at least one of them may also be housed in the first unit
2.
[0027] The configuration of the heat supply system of the present invention is not limited
to the configuration described above, and the heat supply system may be configured
in, e.g., the following manner. The first unit 2 and the second unit 3 may be integrated
with each other instead of being separated from each other. Hot water heated in the
hot water supply heat exchanger 14 may be supplied to the hot water faucet 20 without
intervention of the hot water tank 13. The heating medium having passed through the
first heating device and the second heating device may be circulated directly to the
indoor-heating appliance 21. Water may be used as the heating medium heated by the
first heating device and the second heating device, and hot water having passed through
the first heating device and the second heating device may be supplied directly to
the hot water tank 13 or the hot water faucet 20, for example. The high-temperature
side heat exchanger 8 may be divided into a portion for hot water supply and a portion
for indoor-heating.
[0028] Fig. 2 is a block diagram showing the flow of a signal of the heat supply system
1 of Embodiment 1. As shown in Fig. 2, detection information is inputted to the controller
100 from the hot water temperature sensors 30a, 30b, and 30c, the main thermistor
25, the auxiliary thermistor 24, the low-temperature thermistor 26, the room temperature
thermistor 28, and the flow rate sensor 27. The controller 100 includes a main heat
source operation determination section 101, a main heat source power control section
102, an auxiliary heat source operation determination section 103, a heating medium
pump control section 104, and a water pump control section 105. The controller 100
and a remote control 200 are connected to each other so as to be capable of interactive
data communication. The communication between the controller 100 and the remote control
200 may be wired communication or wireless communication. The remote control 200 includes
an operation section such as a switch operated by a user, and a display section that
displays information on the state of the heat supply system 1 or the like. The controller
100 receives information from the hot water temperature sensors 30a, 30b, and 30c,
the main thermistor 25, the auxiliary thermistor 24, the low-temperature thermistor
26, the room temperature thermistor 28, the flow rate sensor 27, and the remote control
200, and controls the operations of the main heat source 6, the auxiliary heat source
12, the heating medium pump 15, the water pump 16, and the switching valve 17 based
on the information.
[0029] Fig. 3 is a hardware configuration diagram of the controller 100 of the heat supply
system 1 of Embodiment 1. The controller 100 includes a processor 1000 and a memory
1001. The function of the controller 100 is achieved by execution of a program stored
in the memory 1001 by the processor 1000. A plurality of the processors and a plurality
of the memories may achieve the function of the controller 100 in cooperation with
each other.
[0030] A user can perform, e.g., the following operations by operating the remote control
200.
- (1) The user can set target values of the temperature of hot water accumulated in
the hot water tank 13 and the temperature of hot water supplied to the hot water faucet
20.
- (2) The user can set a determination criterion for automation of the operation of
the heat supply system 1. For example, the user can set the criterion of the amount
of hot water or the amount of stored heat in the hot water tank 13 when the heat accumulating
operation is automatically started, and the criterion of the amount of hot water or
the amount of stored heat in the hot water tank 13 when the heat accumulating operation
is automatically ended.
- (3) The user can directly start and end the heat accumulating operation or the indoor-heating
operation.
- (4) The user can set a time period in which the heat accumulating operation or the
indoor-heating operation is performed.
- (5) The user can set a target value of the heating medium supply temperature in the
indoor-heating operation.
- (6) The user can set a target value of room temperature in the indoor-heating operation.
[0031] The controller 100 determines whether the heat accumulating operation or the indoor-heating
operation is necessary according to determination criteria set by the user. The controller
100 may learn the daily use amount of hot water and may predict the use amount of
hot water based on the learning result. The controller 100 may control the heat accumulating
operation such that a hot water shortage in the hot water tank 13 does not occur in
accordance with the predicted use amount of hot water. The controller 100 may automatically
execute the indoor-heating operation based on the target value of the room temperature
set by the user and the detected temperature of the room temperature thermistor 28.
[0032] The main heat source operation determination section 101 determines whether the operation
of the main heat source 6 is necessary. The main heat source power control section
102 controls the heating power of the main heat source 6 by specifying, e.g., the
frequency of the compressor 7. The heating medium pump control section 104 controls
a circulation flow rate of the heating medium by specifying, e.g., the output or rotation
speed of the heating medium pump 15. The controller 100 is capable of performing feedback
control such that the temperature of the heating medium detected by the main thermistor
25 or the auxiliary thermistor 24 converges to a target value. In the feedback control,
the controller 100 may control the heating power of the main heat source 6 such that
the heating power thereof is substantially constant by making the frequency of the
compressor 7 substantially constant, and may adjust the circulation flow rate of the
heating medium.
[0033] The water pump control section 105 controls the flow rate of water that passes through
the hot water supply heat exchanger 14 by specifying, e.g., the output or rotation
speed of the water pump 16. The water pump control section 105 controls the water
pump 16 such that the temperature of hot water accumulated in the hot water tank 13
has the target value. The heating medium pump 15 during the heat accumulating operation
is usually operated such that the heating medium flow rate that prioritizes energy
saving is provided. The heating medium flow rate that prioritizes energy saving is
a flow rate that is substantially equal to the water flow rate by the water pump 16.
The controller 100 may control the heating medium pump 15 and the water pump 16 such
that the heating medium flow rate and the water flow rate become substantially equal
to each other during the heat accumulating operation. Alternatively, the controller
100 may control the heating medium pump 15 and the water pump 16 such that the heating
medium flow rate becomes equal to a value obtained by performing a predetermined correction
on the water flow rate during the heat accumulating operation. For example, in a system
in which a CO
2 refrigerant is used, an influence of deterioration of COP (Coefficient Of Performance)
resulting from an increase in the inlet temperature of the main heat source 6 is more
considerable than an influence of deterioration of COP resulting from an increase
in the outlet temperature of the main heat source 6 in many cases. In such cases,
it is desirable to perform the above correction such that the heating medium flow
rate becomes lower than the water flow rate.
[0034] In the feedback control during the indoor-heating operation, the controller 100 may
substantially fix the circulation flow rate of the heating medium, and may adjust
the heating power of the main heat source 6 such that the temperature of the heating
medium detected by the main thermistor 25 or the auxiliary thermistor 24 converges
to the target value set by the user. During the indoor-heating operation, the controller
100 may change the target value of the heating medium supply temperature in accordance
with a difference between the target value of the room temperature and the detected
temperature of the room temperature thermistor 28, and control the heating power of
the main heat source 6 such that the target value is achieved. Note that, instead
of fixing the circulation flow rate of the heating medium, the rotation speed of the
heating medium pump 15 may also be fixed.
[0035] The auxiliary heat source operation determination section 103 determines whether
the operation of the auxiliary heat source 12 is necessary. For example, when a state
in which the detected temperature of the main thermistor 25 or the auxiliary thermistor
24 is lower than the target value of the heating medium supply temperature continues
for a time period longer than a predetermined time period, the auxiliary heat source
operation determination section 103 may determine the activation of the auxiliary
heat source 12. When a state in which the frequency of the compressor 7 is not less
than a predetermined value and the heating medium supply temperature is lower than
the target value continues for a time period longer than a predetermined time period,
the auxiliary heat source operation determination section 103 may determine the activation
of the auxiliary heat source 12. When a state in which the circulation flow rate of
the heating medium is not more than a predetermined value and the heating medium supply
temperature is lower than the target value continues for a time period longer than
a predetermined time period, the auxiliary heat source operation determination section
103 may determine the activation of the auxiliary heat source 12. When a state in
which the detected temperature of the room temperature thermistor 28 is lower than
the target value of the room temperature continues for a time period longer than a
predetermined time period during the indoor-heating operation, the auxiliary heat
source operation determination section 103 may determine the activation of the auxiliary
heat source 12.
[0036] Fig. 4 is a flowchart of a routine executed by the controller 100 of the heat supply
system 1 of Embodiment 1. The controller 100 executes the routine in Fig. 4 periodically
repeatedly. In Step S1 in Fig. 4, the main heat source operation determination section
101 determines whether the operation of the main heat source 6 is necessary. In the
case where the operation of the main heat source 6 is necessary and the main heat
source 6 is not operated, the main heat source operation determination section 101
activates the main heat source 6. Examples of the case where the operation of the
main heat source 6 is necessary include the case where the user has started the operation
using the remote control 200, the case where a difference between the target value
of the room temperature and the detected temperature of the room temperature thermistor
28 is large, and the case where the heat accumulating operation is automatically started.
The routine transitions from Step S1 to Step S2. In Step S2, the controller 100 determines
whether the main heat source 6 is operated. In the case where the main heat source
6 is not operated, after Step S2, the routine is ended.
[0037] In the case where the main heat source 6 is operated, the routine transitions from
Step S2 to Step S3. In Step S3, the controller 100 performs a process of determining
whether the temperature condition of the heating medium is already stabilized. The
detail of the process will be described later. The routine transitions from Step S3
to Step S4. In Step S4, the determination result in Step S3 is checked. In the case
where the determination result that the temperature condition of the heating medium
is not stabilized yet is obtained, the routine transitions from Step S4 to Step S5.
In Step S5, the controller 100 performs the feedback control on at least one of the
heating power of the main heat source 6 and the circulation flow rate of the heating
medium based on the detected temperature of the auxiliary thermistor 24. In Step S5,
the controller 100 adjusts at least one of the heating power of the main heat source
6 and the circulation flow rate of the heating medium such that the detected temperature
of the auxiliary thermistor 24 converges to the target value of the heating medium
supply temperature. The operation in Step S5 is referred to as a "first operation".
After Step S5, the routine is ended.
[0038] In the case where the determination result that the temperature condition of the
heating medium is already stabilized is obtained, the routine transitions from Step
S4 to Step S6. In Step S6, the controller 100 performs the feedback control on at
least one of the heating power of the main heat source 6 and the circulation flow
rate of the heating medium based on the detected temperature of the main thermistor
25. In Step S6, the controller 100 adjusts at least one of the heating power of the
main heat source 6 and the circulation flow rate of the heating medium such that the
detected temperature of the main thermistor 25 converges to the target value of the
heating medium supply temperature. The operation in Step S6 is referred to as a "second
operation". After Step S6, the routine is ended.
[0039] When the main heat source 6 is activated, the auxiliary heat source 12 is not operated
and is cold. For a certain time period after the activation of the main heat source
6, heat is removed from the heating medium when the heating medium passes through
the auxiliary heat source 12, and the auxiliary heat source 12 is warmed with the
heat of the heating medium. During this time period, the heating medium supply temperature
detected by the main thermistor 25 is significantly reduced as compared with the outlet
temperature of the main heat source 6 detected by the auxiliary thermistor 24. Thereafter,
when the temperature of the auxiliary heat source 12 is stabilized, a difference between
the detected temperature of the auxiliary thermistor 24 and the detected temperature
of the main thermistor 25 is reduced and stabilized. In the process in Step S3 that
determines whether the temperature condition of the heating medium is stabilized,
it is determined whether the difference between the detected temperature of the auxiliary
thermistor 24 and the detected temperature of the main thermistor 25 is stabilized.
[0040] Hereinbelow, an example of a method for determining whether the temperature condition
of the heating medium is stabilized will be described. In Step S3 described above,
it is possible to determine whether the temperature condition of the heating medium
is stabilized by methods in the following examples. In a first example, the controller
100 determines whether the temperature condition of the heating medium is stabilized
based on an elapsed time from the activation of the main heat source 6. In the case
where the elapsed time from the activation of the main heat source 6 has not reached
a predetermined time (e.g., one hour), the controller 100 determines that the temperature
condition of the heating medium is not stabilized yet. In the case where the elapsed
time from the activation of the main heat source 6 has reached the predetermined time,
the controller 100 determines that the temperature condition of the heating medium
is already stabilized.
[0041] Fig. 5 is a flowchart showing a second example of the method for determining whether
the temperature condition of the heating medium is stabilized. In the second example,
the controller 100 determines whether the temperature condition of the heating medium
is stabilized based on the magnitude of a difference between the detected temperature
of the auxiliary thermistor 24 and the detected temperature of the main thermistor
25. In Step S10 in Fig. 5, the controller 100 compares the absolute value of the difference
between the detected temperature of the auxiliary thermistor 24 and the detected temperature
of the main thermistor 25 with a predetermined reference value (e.g., 3°C). In the
case where the absolute value of the temperature difference is more than the reference
value, the flow transitions from Step S10 to Step S11. In Step S11, the controller
100 determines that the temperature condition of the heating medium is not stabilized
yet. In the case where the absolute value of the temperature difference is not more
than the reference value, the flow transitions from Step S10 to Step S 12. In Step
S12, the controller 100 determines that the temperature condition of the heating medium
is already stabilized. This second example corresponds to a feature wherein the controller
100 determines the timing of transition from the first operation to the second operation
based on the difference between the detected temperature of the auxiliary thermistor
24 and the detected temperature of the main thermistor 25. According to the second
example, it is possible to determine whether the temperature condition of the heating
medium is stabilized with high accuracy.
[0042] Note that, in Step S10 described above, it may be determined whether a state in which
the absolute value of the difference between the detected temperature of the auxiliary
thermistor 24 and the detected temperature of the main thermistor 25 is not more than
the reference value continues for a predetermined time period (e.g., one minute) or
longer. In the case where the state does not continue for the predetermined time period
or longer, the flow transitions from Step S10 to Step S11. In the case where the state
continues for the predetermined time period or longer, the flow transitions from Step
S10 to Step S12.
[0043] Fig. 6 is a flowchart showing a third example of the method for determining whether
the temperature condition of the heating medium is stabilized. In the third example,
the controller 100 determines whether the temperature condition of the heating medium
is stabilized based on a fluctuation range of the difference between the detected
temperature of the auxiliary thermistor 24 and the detected temperature of the main
thermistor 25. In Step S15 in Fig. 6, the controller 100 determines whether a state
in which the fluctuation range of the absolute value of the difference between the
detected temperature of the auxiliary thermistor 24 and the detected temperature of
the main thermistor 25 is not more than a predetermined reference value (e.g., 3°C)
continues for a predetermined time period (e.g., one minute) or longer. In the case
where the state does not continue for the predetermined time period or longer, the
flow transitions from Step S15 to Step S16. In Step S16, the controller 100 determines
that the temperature condition of the heating medium is not stabilized yet. In the
case where the state continues for the predetermined time period or longer, the flow
transitions from Step S15 to Step S17. In Step S17, the controller 100 determines
that the temperature condition of the heating medium is already stabilized. This third
example corresponds to a feature wherein the controller 100 determines the timing
of transition from the first operation to the second operation based on the fluctuation
range of the difference between the detected temperature of the auxiliary thermistor
24 and the detected temperature of the main thermistor 25. According to the third
example, it is possible to determine whether the temperature condition of the heating
medium is stabilized with high accuracy.
[0044] Fig. 7 is a graph showing an example of the change in the detected temperature of
each of the main thermistor 25 and the auxiliary thermistor 24 after the activation
of the main heat source 6. The example shown in Fig. 7 is the example in the case
where the controller 100 controls at least one of the heating power of the main heat
source 6 and the circulation flow rate of the heating medium based only on the detected
temperature of the main thermistor 25 from immediately after the activation of the
main heat source 6 without executing the routine in Fig. 4. In the example of the
control in Fig. 7, the controller 100 corrects at least one of the heating power of
the main heat source 6 and the circulation flow rate of the heating medium such that
the detected temperature of the main thermistor 25 converges to the target value of
the heating medium supply temperature from immediately after the activation of the
main heat source 6. The example of the control in Fig. 7 does not correspond to Embodiment
1.
[0045] For a certain time period after the activation of the main heat source 6, heat is
removed from the heating medium while the heating medium passes through the auxiliary
heat source 12, and the auxiliary heat source 12 is warmed with the heat of the heating
medium. During this time period, the heating medium supply temperature detected by
the main thermistor 25 is significantly reduced as compared with the outlet temperature
of the main heat source 6 detected by the auxiliary thermistor 24. In the example
of the control in Fig. 7, during this time period, at least one of a correction that
increases the heating power of the main heat source 6 and a correction that reduces
the circulation flow rate of the heating medium is performed in order to cause the
detected temperature of the main thermistor 25 to approach the target value. An increase
in the detected temperature of the main thermistor 25 tends to lag behind an increase
in the outlet temperature of the main heat source 6. A first reason for the lagging
is that it takes time for the temperature of the auxiliary heat source 12 having a
large heat capacity to increase. A second reason therefor is a delay caused by transferring
the heating medium from the outlet of the main heat source 6 to the position of the
main thermistor 25. While the increase in the detected temperature of the main thermistor
25 lags, the heating power of the main heat source 6 is corrected to an extremely
high value, or the circulation flow rate of the heating medium is corrected to an
extremely low value. As a result, the outlet temperature of the main heat source 6
detected by the auxiliary thermistor 24 significantly exceeds the target value, and
overshoots. Subsequently to the overshooting of the detected temperature of the auxiliary
thermistor 24, the heating medium supply temperature detected by the main thermistor
25 also significantly exceeds the target value, and overshoots. Thus, in the example
of the control shown in Fig. 7, both of the detected temperature of the auxiliary
thermistor 24 and the detected temperature of the main thermistor 25 significantly
exceed the target value, and overshoot. In the example of the control shown in Fig.
7, it is not possible to prevent the overshooting of the heating medium supply temperature.
In the example of the control shown in Fig. 7, the load of the main heat source 6
tends to be increased, and hence the life of the main heat source 6 may be reduced.
[0046] Fig. 8 is a graph showing an example of the change in the detected temperature of
each of the main thermistor 25 and the auxiliary thermistor 24 after the activation
of the main heat source 6. The example shown in Fig. 8 is the example in the case
where the controller 100 controls at least one of the heating power of the main heat
source 6 and the circulation flow rate of the heating medium based only on the detected
temperature of the auxiliary thermistor 24 without using the detected temperature
of the main thermistor 25. In the example of the control in Fig. 8, the controller
100 corrects at least one of the heating power of the main heat source 6 and the circulation
flow rate of the heating medium such that the detected temperature of the auxiliary
thermistor 24 converges to the target value of the heating medium supply temperature
from immediately after the activation of the main heat source 6. The example of the
control in Fig. 8 does not correspond to Embodiment 1.
[0047] In the example of the control in Fig. 8, after the activation of the main heat source
6, the outlet temperature of the main heat source 6 detected by the auxiliary thermistor
24 converges to the target value of the heating medium supply temperature without
significantly overshooting, and is stabilized. After the outlet temperature of the
main heat source 6 is stabilized, the heating medium supply temperature detected by
the main thermistor 25 is lower than the outlet temperature of the main heat source
6. The reason for that is that the temperature of the heating medium is reduced due
to heat dissipation from the heating medium pipe 5 from the main heat source 6 to
the position of the main thermistor 25. In the example of the control in Fig. 8, the
heating medium supply temperature detected by the main thermistor 25 converges to
a temperature lower than the target value, and is stabilized. That is, in the example
of the control in Fig. 8, the heating medium supply temperature detected by the main
thermistor 25 does not reach the target value, and undershoots.
[0048] Fig. 9 is a graph showing an example of the change in the detected temperature of
each of the main thermistor 25 and the auxiliary thermistor 24 after the activation
of the main heat source 6. The example shown in Fig. 9 is the example in the case
where the controller 100 performs control based on the routine shown in Fig. 4. The
example of the control in Fig. 9 corresponds to Embodiment 1. A time t1 in Fig. 9
is a time when the controller 100 determines that the temperature condition of the
heating medium is already stabilized in Step S3 in Fig. 4. During a time period before
the time t1, the controller 100 controls at least one of the heating power of the
main heat source 6 and the circulation flow rate of the heating medium based on the
detected temperature of the auxiliary thermistor 24. During the time period before
the time t1, the controller 100 corrects at least one of the heating power of the
main heat source 6 and the circulation flow rate of the heating medium such that the
detected temperature of the auxiliary thermistor 24 converges to the target value
of the heating medium supply temperature. The operation during the time period before
the time t1 corresponds to the first operation. In the first operation, the outlet
temperature of the main heat source 6 detected by the auxiliary thermistor 24 converges
to the target value of the heating medium supply temperature without significantly
overshooting. In the first operation, the heating medium supply temperature detected
by the main thermistor 25 converges to a temperature lower than the target value.
[0049] After the time t1, the controller 100 controls at least one of the heating power
of the main heat source 6 and the circulation flow rate of the heating medium based
on the detected temperature of the main thermistor 25. After the time t1, the controller
100 corrects at least one of the heating power of the main heat source 6 and the circulation
flow rate of the heating medium such that the detected temperature of the main thermistor
25 converges to the target value of the heating medium supply temperature. The operation
after the time t1 corresponds to the second operation. The detected temperature of
the main thermistor 25 immediately after the start of the second operation is lower
than the target value of the heating medium supply temperature. As a result, the controller
100 performs at least one of the correction that increases the heating power of the
main heat source 6 and the correction that reduces the circulation flow rate of the
heating medium such that the detected temperature of the main thermistor 25 is increased.
With this correction, the heating medium supply temperature detected by the main thermistor
25 converges to the target value and is stabilized without significantly overshooting.
[0050] As shown in Fig. 9, according to the present embodiment, the following effects are
obtained. It is possible to prevent the overshooting and the undershooting of the
heating medium supply temperature. It is possible to avoid an excessive increase in
the outlet temperature of the main heat source 6. After the system is stabilized,
it is possible to reliably increase the heating medium supply temperature to the heat
use terminal to the target value.
Embodiment 2
[0051] Next, Embodiment 2 of the present invention will be described with reference to Figs.
10 to 12. Points different from the above-described embodiment will be mainly described,
and the same or equivalent portions are designated by the same reference numerals
and the description thereof will be omitted. The equipment configuration of the heat
supply system 1 of Embodiment 2 is the same as that of Embodiment 1 shown in Figs.
1 to 3, and hence the depiction and description thereof will be omitted.
[0052] In the heat supply system 1 of the present embodiment, in the case where it is determined
that the heating power of the main heat source 6 is insufficient during the operation
of the main heat source 6, similarly to Embodiment 1, the auxiliary heat source operation
determination section 103 determines that the auxiliary heat source 12 is activated.
When the auxiliary heat source 12 is activated, the heating medium heated by the main
heat source 6 is further heated by the auxiliary heat source 12, and the heating medium
supply temperature detected by the main thermistor 25 may thereby overshoot. In the
present embodiment, when the auxiliary heat source 12 is activated, the controller
100 performs adjustment so as to reduce the heating power of the main heat source
6 such that the overshooting of the heating medium supply temperature detected by
the main thermistor 25 is prevented. In the present embodiment, the controller 100
performs the adjustment so as to reduce the heating power of the main heat source
6 concurrently with the activation of the auxiliary heat source 12.
[0053] Fig. 10 is a flowchart of a routine executed by the controller 100 of the heat supply
system 1 of Embodiment 2. The controller 100 executes the routine in Fig. 10 periodically
repeatedly. In Step S20 in Fig. 10, the controller 100 determines whether the main
heat source 6 is operated. In the case where the main heat source 6 is not operated,
after Step S20, the routine is ended. In the case where the main heat source 6 is
operated, the routine transitions from Step S20 to Step S21. In Step S21, the auxiliary
heat source operation determination section 103 determines whether the operation of
the auxiliary heat source 12 is necessary. The routine transitions from Step S21 to
Step S22. In Step S22, the controller 100 determines whether the auxiliary heat source
12 is operated. In the case where the auxiliary heat source 12 is not operated, after
Step S22, the routine is ended.
[0054] In the case where the auxiliary heat source 12 is operated, the routine transitions
from Step S22 to Step S23. In Step S23, the controller 100 determines whether the
adjustment of the heating power of the main heat source 6 in the case where the auxiliary
heat source 12 is activated is completed. In the case where the adjustment of the
heating power of the main heat source 6 is not completed, the routine transitions
from Step S23 to Step S24. In Step S24, the controller 100 performs the adjustment
of the heating power of the main heat source 6 in the case where the auxiliary heat
source 12 is activated. In Step S24, the controller 100 performs the adjustment so
as to reduce the heating power of the main heat source 6. In Step S23, in the case
where the adjustment of the heating power of the main heat source 6 is already completed,
the routine is ended.
[0055] Examples of a method according to which the controller 100 performs the adjustment
so as to reduce the heating power of the main heat source 6 in Step S24 will be described
below.
[0056] (Example 1) The heating power of the main heat source 6 is reduced at a predetermined
rate. For example, the adjustment is performed such that the frequency of the compressor
7 is reduced to half of the current frequency.
[0057] (Example 2) The heating power of the main heat source 6 is reduced at a rate determined
based on rated powers of the main heat source 6 and the auxiliary heat source 12.
In a situation where the auxiliary heat source 12 is activated, it is possible to
assume that the main heat source 6 outputs the rated power. For example, in the case
where it is assumed that the rated power of the main heat source 6 is 5 kW and the
rated power of the auxiliary heat source 12 is 2 kW, the frequency of the compressor
7 is adjusted to the frequency obtained by multiplying the frequency of the compressor
7 by 3/5 such that the heating power of the main heat source 6 becomes 3 kW.
[0058] (Example 3) The heating power of the main heat source 6 required after the activation
of the auxiliary heat source 12 is calculated such that the heating medium supply
temperature after the activation of the auxiliary heat source 12 reaches the target
value, and the heating power of the main heat source 6 is adjusted based on the calculation
result. An example of a method for calculating the heating power of the main heat
source 6 required after the activation of the auxiliary heat source 12 will be described
below. It is assumed that the detected temperature of the main thermistor 25 or the
auxiliary thermistor 24 before the heating power of the main heat source 6 is reduced
is TH, the detected temperature of the low-temperature thermistor 26 before the heating
power of the main heat source 6 is TL, the detected flow rate of the flow rate sensor
27 is Gvw, the target value of the detected temperature of the main thermistor 25
or the auxiliary thermistor 24 is THm, the density of the heating medium is p, and
the specific heat of the heating medium is C. A heating power Qn0 of the main heat
source 6 before the heating power of the main heat source 6 is reduced can be calculated
by the following expression.

[0059] It is assumed that the heating power of the auxiliary heat source 12 is Qs, and the
heating power of the main heat source 6 required after the activation of the auxiliary
heat source 12 is Qm1. Qm1 can be calculated by the following expression.

[0060] In Example 3, in Step S24 in Fig. 10, the heating power of the main heat source 6
is adjusted to Qm1. In order to do so, the heating power of the main heat source 6
may be adjusted so as to be reduced to the heating power obtained by multiplying the
heating power of the main heat source 6 by Qm1/Qm0. In order to perform the above
adjustment, for example, the frequency of the compressor 7 may be adjusted to the
frequency obtained by multiplying the frequency thereof by Qm1/Qm0. By performing
the adjustment in this manner, it is possible to cause the heating medium supply temperature
after the activation of the auxiliary heat source 12 to approach the target value
with high accuracy.
[0061] Specific numerical examples are shown below. It is assumed that the detected temperature
of the main thermistor 25 or the auxiliary thermistor 24 before the heating power
of the main heat source 6 is reduced is 45°C, the detected temperature of the low-temperature
thermistor 26 before the heating power of the main heat source 6 is reduced is 30°C,
the detected flow rate of the flow rate sensor 27 is 3 liters/minute, the heating
power of the auxiliary heat source 12 is 2 kW, and the target value of the detected
temperature of the main thermistor 25 or the auxiliary thermistor 24 is 50°C. At this
point, the heating power of the main heat source 6 before the heating power of the
main heat source 6 is reduced is 3.14 kW, and the heating power of the main heat source
6 required after the activation of the auxiliary heat source 12 is 2.18 kW. In this
case, by adjusting the frequency of the compressor 7 to the frequency obtained by
multiplying the frequency pf the compressor 7 by 0.69, it is possible to cause the
heating medium supply temperature after the activation of the auxiliary heat source
12 to approach the target value 50°C with high accuracy.
[0062] Fig. 11 is a graph showing an example of the change in the temperatures in the vicinity
of the upstream side and the downstream side of the auxiliary heat source 12 in the
case where the auxiliary heat source 12 is activated in a state in which the main
heat source 6 is operated and the auxiliary heat source 12 is not operated. The example
shown in Fig. 11 is the example in the case where it is assumed that the controller
100 does not execute the process in Step S24 in Fig. 10. That is, the example shown
in Fig. 11 is the example in the case where it is assumed that the controller 100
does not perform the adjustment of the heating power of the main heat source 6 resulting
from the activation of the auxiliary heat source 12. The example in Fig. 11 does not
correspond to Embodiment 2.
[0063] The temperature in the vicinity of the downstream side of the auxiliary heat source
12 in Fig. 11 corresponds to the heating medium supply temperature detected by the
main thermistor 25. A time t2 in Fig. 11 is a time when the auxiliary heat source
12 is activated. Before the time t2, the temperature in the vicinity of the downstream
side of the auxiliary heat source 12 converges to a temperature lower than the target
value. Because of this, it is determined that the heating power of the main heat source
6 is insufficient, and the auxiliary heat source 12 is activated. When the auxiliary
heat source 12 is activated at the time t2, the temperature in the vicinity of the
downstream side of the auxiliary heat source 12 sharply increases, significantly exceeds
the target value, and overshoots. The controller 100 detects the overshooting with
the main thermistor 25. As a result, by the feedback control of the controller 100,
the heating power of the main heat source 6 is corrected so as to be reduced. A time
t3 in Fig. 11 is a time when the reduction of the temperature in the vicinity of the
upstream side of the auxiliary heat source 12 is started by the correction. With the
reduction of the temperature in the vicinity of the upstream side of the auxiliary
heat source 12, the temperature in the vicinity of the downstream side of the auxiliary
heat source 12 is reduced. Thereafter, the temperature in the vicinity of the downstream
side of the auxiliary heat source 12 converges to the target value. In the example
shown in Fig. 11, the heating power of the main heat source 6 is not corrected so
as to be reduced before the overshooting of the temperature in the vicinity of the
downstream side of the auxiliary heat source 12. Accordingly, it is not possible to
prevent the overshooting of the temperature in the vicinity of the downstream side
of the auxiliary heat source 12, i.e., the heating medium supply temperature.
[0064] Fig. 12 is a graph showing an example of the change in the temperatures in the vicinity
of the downstream side and the upstream side of the auxiliary heat source 12 in the
case where the auxiliary heat source 12 is activated in the state in which the main
heat source 6 is operated and the auxiliary heat source 12 is not operated. The example
of the control in Fig. 12 is the example in the case where the controller 100 executes
the process in Step S24 in Fig. 10. The example of the control in Fig. 12 corresponds
to Embodiment 2.
[0065] A time t4 in Fig. 12 is a time when the auxiliary heat source 12 is activated. Before
the time t4, the temperature in the vicinity of the downstream side of the auxiliary
heat source 12 converges to a temperature lower than the target value. Because of
this, it is determined that the heating power of the main heat source 6 is insufficient,
and the auxiliary heat source 12 is activated. Concurrently with the activation of
the auxiliary heat source 12, with the process in Step S24 in Fig. 10, the adjustment
that reduces the heating power of the main heat source 6 is performed. With this,
soon after the activation of the auxiliary heat source 12, the temperature in the
vicinity of the upstream side of the auxiliary heat source 12 is reduced. As a result,
the temperature in the vicinity of the downstream side of the auxiliary heat source
12 is prevented from significantly exceeding the target value. That is, the overshooting
of the heating medium supply temperature is prevented.
[0066] In a system in which the heat pump of the main heat source 6 uses the CO
2 refrigerant, there are cases where the circulation flow rate of the heating medium
is set to be low for the purpose of obtaining high COP. In general, in such a system,
the heating medium supply temperature tends to overshoot when the auxiliary heat source
12 is activated. According to Embodiment 2, even in the system, it is possible to
reliably prevent the overshooting of the heating medium supply temperature when the
auxiliary heat source 12 is activated.
Embodiment 3
[0067] Next, Embodiment 3 of the present invention will be described with reference to Figs.
13 to 15. Points different from the embodiments described above will be mainly described,
and the same or equivalent portions are designated by the same reference numerals
and the description thereof will be omitted. The equipment configuration of the heat
supply system 1 of Embodiment 3 is the same as that of Embodiment 1 shown in Figs.
1 to 3, and hence the depiction and description thereof will be omitted.
[0068] In the heat supply system 1 of the present embodiment, in the case where it is determined
that the heating power of the main heat source 6 is insufficient during the operation
of the main heat source 6, similarly to Embodiment 1, the auxiliary heat source operation
determination section 103 determines that the auxiliary heat source 12 is activated.
In Embodiment 2 described above, concurrently with the activation of the auxiliary
heat source 12, the controller 100 performs the adjustment so as to reduce the heating
power of the main heat source 6. In contrast to this, in the present embodiment, the
controller 100 performs the adjustment so as to reduce the heating power of the main
heat source 6 before the activation of the auxiliary heat source 12. In a system in
which the length of a flow path from the main heat source 6 to the auxiliary heat
source 12 is large, it takes time for an effect of the adjustment that reduces the
heating power of the main heat source 6 to reach the position of the auxiliary heat
source 12. That is, in the system in which the length or the flow path from the main
heat source 6 to the auxiliary heat source 12 is large, it takes time for the temperature
in the vicinity of the upstream side of the auxiliary heat source 12 to start its
reduction after the heating power of the main heat source 6 is reduced. In the present
embodiment, in the case where it is determined that the auxiliary heat source 12 is
activated during the operation of the main heat source 6, after the controller 100
performs the adjustment so as to reduce the heating power of the main heat source
6, the controller 100 temporarily halts the activation of the auxiliary heat source
12 until the effect reaches the position of the auxiliary heat source 12. The controller
100 activates the auxiliary heat source 12 after the effect of the adjustment of the
heating power of the main heat source 6 reaches the position of the auxiliary heat
source 12. According to the present embodiment, even in the system in which the length
of the flow path from the main heat source 6 to the auxiliary heat source 12 is large,
it is possible to reliably prevent the overshooting of the heating medium supply temperature
when the auxiliary heat source 12 is activated.
[0069] Fig. 13 is a flowchart of a routine executed by the controller 100 of the heat supply
system 1 of Embodiment 3. The controller 100 executes the routine in Fig. 13 periodically
repeatedly. In Step S30 in Fig. 13, the controller 100 determines whether the main
heat source 6 is operated. In the case where the main heat source 6 is not operated,
after Step S30, the routine is ended. In the case where the main heat source 6 is
operated, the routine transitions from Step S30 to Step S31. In Step S31 the auxiliary
heat source operation determination section 103 determines whether the operation of
the auxiliary heat source 12 is necessary. The routine transitions from Step S31 to
Step S32. In Step S32, the controller 100 determines whether the operation of the
auxiliary heat source 12 is determined. In the case where the auxiliary heat source
12 is not operated, after Step S32, the routine is ended.
[0070] In the case where the operation of the auxiliary heat source 12 is determined, the
routine transitions from Step S32 to Step S33. In Step S33, the controller 100 determines
whether the adjustment of the heating power of the main heat source 6 before the auxiliary
heat source 12 is activated is completed. In the case where the adjustment of the
heating power of the main heat source 6 is not completed, the routine transitions
from Step S33 to Step S34. In Step S34, the controller 100 performs the adjustment
of the heating power of the main heat source 6 before the auxiliary heat source 12
is activated. In Step S34, the controller 100 performs the adjustment so as to reduce
the heating power of the main heat source 6. The adjustment method in Step S34 is
the same as the adjustment method in Step S24 in Embodiment 2 described above. The
routine transitions from Step S34 to Step S35. In Step S35, the controller 100 temporarily
halts the activation of the auxiliary heat source 12. After Step S35, the routine
is ended.
[0071] In Step S33, in the case where the adjustment of the heating power of the main heat
source 6 is already completed, the routine transitions to Step S36. In Step S36, the
controller 100 determines whether the effect of the adjustment of the heating power
of the main heat source 6 has reached the position of the auxiliary heat source 12.
In the case where it is determined that the effect of the adjustment of the heating
power of the main heat source 6 has not reached the position of the auxiliary heat
source 12 yet, the routine transitions from Step S35 to Step S37. In Step S37, the
controller 100 temporarily halts the activation of the auxiliary heat source 12. After
Step S37, the routine is ended.
[0072] In Step S36, in the case where it is determined that the effect of the adjustment
of the heating power of the main heat source 6 has reached the position of the auxiliary
heat source 12, the routine transitions from Step S36 to Step S38. In Step S38, the
controller 100 activates the auxiliary heat source 12. In Step S38, in the case where
the auxiliary heat source 12 is already activated, the controller 100 continues the
operation of the auxiliary heat source 12. After Step S38, the routine is ended.
[0073] Fig. 14 is a graph showing an example of the change in the temperatures in the vicinity
of the downstream side and the upstream side of the auxiliary heat source 12 in the
case where the auxiliary heat source 12 is activated in the state in which the main
heat source 6 is operated and the auxiliary heat source 12 is not operated. The example
shown in Fig. 14 is the example in the case where it is assumed that the adjustment
of the heating power of the main heat source 6 is performed concurrently with the
activation of the auxiliary heat source 12 in the system in which the length of the
flow path from the main heat source 6 to the auxiliary heat source 12 is large.
[0074] The temperature in the vicinity of the downstream side of the auxiliary heat source
12 in Fig. 14 corresponds to the heating medium supply temperature detected by the
main thermistor 25. A time t5 in Fig. 14 is a time when the auxiliary heat source
12 is activated and the adjustment that reduces the heating power of the main heat
source 6 is performed. Before the time t5, the temperature in the vicinity of the
downstream side of the auxiliary heat source 12 converges to a temperature lower than
the target value. Because of this, it is determined that the heating power of the
main heat source 6 is insuffcient, and the auxiliary heat source 12 is activated.
It takes time for the temperature in the vicinity of the upstream side of the auxiliary
heat source 12 to start its reduction after the heating power of the main heat source
6 is adjusted so as to be reduced at the time t5. For a certain time period after
the activation of the auxiliary heat source 12, the temperature in the vicinity of
the upstream side of the auxiliary heat source 12 is equal to the temperature before
the adjustment of the heating power of the main heat source 6. Accordingly, when the
auxiliary heat source 12 heats the heating medium, the temperature in the vicinity
of the downstream side of the auxiliary heat source 12 sharply increases, and overshoots.
A time t6 in Fig. 14 is a time when the effect of the adjustment of the heating power
of the main heat source 6 reaches the position of the auxiliary heat source 12. That
is, the time t6 is the time when the temperature in the vicinity of the upstream side
of the auxiliary heat source 12 starts its reduction. Thereafter, with the reduction
of the temperature in the vicinity of the upstream side of the auxiliary heat source
12, the temperature in the vicinity of the downstream side of the auxiliary heat source
12 is reduced.
[0075] Fig. 15 is a graph showing an example of the change in the temperatures in the vicinity
of the downstream side and the upstream side of the auxiliary heat source 12 in the
case where the auxiliary heat source 12 is activated in the state in which the main
heat source 6 is operated and the auxiliary heat source 12 is not operated. The example
of the control in Fig. 15 is the example in the case where the controller 100 executes
the routine in Fig. 13. The example of the control in Fig. 15 corresponds to Embodiment
3.
[0076] A time t7 in Fig. 15 is a time when the activation of the auxiliary heat source 12
is determined. Before the time t7, the temperature in the vicinity of the downstream
side of the auxiliary heat source 12 converges to a temperature lower than the target
value. Because of this, it is determined that the heating power of the main heat source
6 is insufficient, and the activation of the auxiliary heat source 12 is determined.
When the activation of the auxiliary heat source 12 is determined, with the process
in Step S34 in Fig. 13, the adjustment that reduces the heating power of the main
heat source 6 is performed. With this, the temperature in the vicinity of the downstream
side of the main heat source 6 is reduced. Atime t8 in Fig. 15 is a time when the
effect of the adjustment of the heating power of the main heat source 6 reaches the
position of the auxiliary heat source 12. That is, the time t8 is the time when the
temperature in the vicinity of the upstream side of the auxiliary heat source 12 starts
its reduction. At the time t8, the auxiliary heat source 12 is activated. When the
auxiliary heat source 12 is activated, the reduction of the temperature in the vicinity
of the upstream side of the auxiliary heat source 12 is already started. Accordingly,
after the activation of the auxiliary heat source 12, the temperature in the vicinity
of the downstream side of the auxiliary heat source 12 is prevented from significantly
exceeding the target value. That is, the overshooting of the heating medium supply
temperature is prevented.
[0077] In the system in which the heat pump of the main heat source 6 uses the CO
2 refrigerant, there are cases where the circulation flow rate of the heating medium
is set to be low for the purpose of obtaining high COP. In general, in such a system,
the heating medium supply temperature tends to overshoot when the auxiliary heat source
12 is activated. According to Embodiment 3, even in the system, it is possible to
reliably prevent the overshooting of the heating medium supply temperature when the
auxiliary heat source 12 is activated.
[0078] Examples of a method according to which the controller 100 determines whether the
effect of the adjustment of the heating power of the main heat source 6 has reached
the position of the auxiliary heat source 12 in Step S36 will be described below.
[0079] (Example 1) The controller 100 can determine whether the effect of the adjustment
of the heating power of the main heat source 6 has reached the position of the auxiliary
heat source 12 based on an elapsed time after the adjustment of the heating power
of the main heat source 6. For example, the controller 100 determines that the effect
of the adjustment of the heating power of the main heat source 6 has not reached the
position of the auxiliary heat source 12 in the case where the elapsed time has not
reached a predetermined time (e.g., 30 minutes), and the controller 100 determines
that the effect of the adjustment of the heating power of the main heat source 6 has
reached the position of the auxiliary heat source 12 in the case where the elapsed
time has reached the predetermined time. In the case of Example 1, the controller
100 activates the auxiliary heat source 12 in response to the elapsed time after the
reduction of the heating power of the main heat source 6 having reached the predetermined
time.
[0080] (Example 2) The controller 100 can determine whether the effect of the adjustment
of the heating power of the main heat source 6 has reached the position of the auxiliary
heat source 12 based on a detected temperature of a temperature sensor disposed in
the vicinity of the downstream side or the upstream side of the auxiliary heat source
12. In the case of the configuration example in Fig. 1, it is possible to use the
main thermistor 25 as the temperature sensor. For example, in the case where the detected
temperature is reduced by a predetermined amount (e.g., 3°C) or more as compared with
the detected temperature before the adjustment of the heating power of the main heat
source 6, the controller 100 determines that the effect of the adjustment of the heating
power of the main heat source 6 has reached the position of the auxiliary heat source
12. In the case of Example 2, the controller 100 activates the auxiliary heat source
12 in response to the reduction of the detected temperature by the predetermined amount
(e.g., 3°C) or more as compared with the detected temperature before the adjustment
of the heating power of the main heat source 6. In addition, in the case where the
detected temperature is significantly reduced in a short time period (e.g., in the
case where the detected temperature is reduced by 3°C or more in one minute), the
controller 100 may determine that the effect of the adjustment of the heating power
of the main heat source 6 has reached the position of the auxiliary heat source 12.
[0081] (Example 3) It is assumed that the detected flow rate of the flow rate sensor 27
is Gvw, the target value of the heating medium supply temperature is THm, the density
of the heating medium is p, the specific heat of the heating medium is C, and the
heating power of the auxiliary heat source 12 is Qs. When the detected temperature
of the temperature sensor disposed in the vicinity of the downstream side or the upstream
side of the auxiliary heat source 12 becomes equal to or close to (THm - Qs/p/C/Gvw),
the controller 100 determines that the effect of the adjustment of the heating power
of the main heat source 6 has reached the position of the auxiliary heat source 12,
and activates the auxiliary heat source 12. According to Example 3, it is possible
to immediately cause the heating medium supply temperature to converge to the target
value THm after the activation of the auxiliary heat source 12.
[0082] (Example 4) In the case where a difference between the detected temperature of the
main thermistor 25 and the detected temperature of the auxiliary thermistor 24 is
stabilized, the controller 100 determines that the effect of the adjustment of the
heating power of the main heat source 6 has reached the position of the auxiliary
heat source 12, and activates the auxiliary heat source 12. According to Example 4,
it is possible to reliably prevent both of the overshooting and the undershooting
of the heating medium supply temperature.
[0083] Thus, the embodiments of the present invention have been described, and a plurality
of the embodiments described above may be arbitrarily combined and implemented in
the present invention.
[Reference Signs List]
[0084]
1 heat supply system
2 first unit
3 second unit
4, 5 heating medium pipe
6 main heat source
7 compressor
8 high-temperature side heat exchanger
9 decompression device
10 low-temperature side heat exchanger
11 blower
12 auxiliary heat source
13 hot water tank
14 hot water supply heat exchanger
15 heating medium pump
16 water pump
17 switching valve
18 water supply pipe
19 hot water supply pipe
20 hot water faucet
21 indoor-heating appliance
22,23 heating medium pipe
24 auxiliary thermistor
25 main thermistor
26 low-temperature thermistor
27 flow rate sensor
28 room temperature thermistor
30a, 30b, 30c hot water temperature sensor
40 water source
100 controller
101 main heat source operation determination section
102 main heat source power control section
103 auxiliary heat source operation determination section
104 heating medium pump control section
105 water pump control section
200 remote control
1000 processor
1001 memory