[0001] The invention relates to a flow guiding apparatus for a heating device and to a heating
device comprising said apparatus. Also, the invention relates to a use of said flow
guiding apparatus in a heating device, in particular an air-source heat pump water
heater using a flammable refrigerant.
[0002] A heating device like a heat pump is a device able to warm a closed space of a building
or to warm domestic hot water by transferring thermal energy from a source to another.
An air-source heat pump water heater is a device using the heat pump technology to
use energy from air to heat the domestic water contained in a tank. This is obtained
using a refrigeration cycle carried out in the opposite direction of the heat transfer.
Among the different refrigeration cycles, the most widely used is the vapor compression
refrigeration, in which a refrigerant undergoes phase changes.
[0003] For a heat pump water heater, vapor-compression refrigeration uses a circulating
liquid refrigerant as the medium which absorbs heat from one source, compresses it,
thereby increasing its temperature before releasing it in another source. A vapor-compression
refrigeration system usually comprises at least a compressor, an expansion valve and,
two heat exchangers and a network of pipes connecting these elements and in which
the refrigerant circulates. In a heating mode the external heat exchanger is the evaporator
and the internal one being the condenser. In particular, the thermodynamic circuit
of a heat pump water heater comprises a first stage, or hot stage, including the condenser,
and a second stage, or cold stage, including the evaporator. A heat transfer fluid
circulates in a closed circuit, wherein this fluid flows in the evaporator at low
pressure. At the evaporator outlet, the fluid is compressed by the compressor and
flows in the condenser before passing through an expansion valve. The valve lowers
the fluid's pressure so that the fluid can return to the evaporator. The condenser
is usually arranged in, or around, a water tank in order to determine a heat transfer,
whereas the evaporator is crossed by an air circulation path and is coupled to a fan
element.
[0004] Through the evaporator circulate fluids such as R410A, R-32, R134a, to evaporate/vaporize
from liquid to gas within the system while absorbing heat from a source in the process.
However, environmental constraints prevent the use of historical refrigerants and
lead to the use of new so-called natural fluids. These fluids are highly flammable
and can therefore generate risks of explosion in the event of a leak in an electrical
appliance that has not been designed to control this risk. For example, the presence
of the compressor and more generally of a source of ignition close to the evaporator
can strongly affect the safety of the heating device. An ignition source is an item
or substance capable of an energy release sufficient to ignite a flammable fluid.
It can be of several natures including hot source and electrical, mechanical or chemical
activation energy.
[0005] As mentioned above, to operate, the heat pump circuit needs an expansion valve. The
function of the expansion valve is to expand the refrigerant from high pressure to
low pressure. This serves also to control the amount of refrigerant released into
the evaporator and regulate the superheat of the refrigerant that flows out of the
evaporator to a constant and defined value. To do it so, the expansion valve needs
a thermal bulb/sensor to regulate the superheat by influencing the flow rate. To absolve
this function, the sensor is positioned on the frigorific piping between the evaporator
outlet and the compressor inlet. It is isolated from the air flow thanks to insulating
means (mainly foam) and is fixed to the piping with a temperature-conducting solution.
As this probe cannot be immersed in the refrigerant, it is placed in contact with
the conductive tube in which circulates the refrigerant. This can be achieved for
example by using a copper (for high thermal conductivity) housing soldered, screwed
or clipped onto the refrigerant circuit, by using an adhesive with a temperature-conducting
aluminium surface or by using a thermally conductive adhesive paste.
[0006] However, based on the arrangement of the components of the heating device, the expansion
valve could not function correctly. For example, in designs where the evaporator is
confined in a region where airflow is prevented from cooling more elements than necessary,
especially the compressor and the refrigerant pipes going from the compressor to the
condenser (useful heat), it would be reasonable to place the temperature sensor of
the expansion valve on the piping located outside the air flow in order to not have
any deviation due to the air temperature. However, this would lead to a malfunctioning
of the expansion valve. As a matter of fact, the temperature read by the temperature
sensor is biased because the compressor will heat the piping and therefore the probe
by conduction. Moreover, as there is no air circulation allowing thermal convection
around all the components of the heat pump (and in particular the compressor and frigorific
piping associated), the whole environment increases in temperature. It is therefore
necessary to position the temperature sensor in a place where the temperature read
by the probe will not be biased by external behaviours that would distort the read
temperature value of the refrigerant (as the heating of the compressor). Indeed, if
the sensor overheats, it would act like if there is not enough fluid in the evaporator
and open the expansion valve.
[0007] When opening the hot gas valve, there is no overheat identified so the expansion
valve would act like if there is too much fluid in the evaporator and close the expansion
valve.
[0008] It is therefore desirable to obtain an apparatus or system able to control the situation
of leakage of flammable fluid at the evaporator and at the same time able to correctly
monitor the temperature of the refrigerant fluid for a correct functioning of the
expansion valve.
[0009] The object is solved by a flow guiding apparatus for a heating device, in particular
an air-source heat pump water heater using a flammable refrigerant, the heating device
including at least a heat exchanger, a compressor element, an expansion valve and
a temperature sensor connectable to the expansion valve for monitoring the temperature
of the refrigerant flowing out the heat exchanger, the apparatus comprising: a housing
couplable to a casing of the heating device and comprising an air inlet and an air
outlet, the housing defining an air flow region, wherein the housing is configured
so that the heat exchanger is arranged inside the air flow region for exchanging heat
in said air flow region, and so that air is guided to flow from the air inlet to the
heat exchanger and from the heat exchanger to the air outlet, the air being confined
in the air flow region and being prevented from being in contact with the compressor
element and the expansion valve that are arranged outside the air flow region, and
wherein the housing is shaped to place in the air flow region the temperature sensor
connectable to the expansion valve.
[0010] Advantageously, the apparatus can be integrated in a heat pump water heater and the
heat exchanger is an evaporator operating with a flammable refrigerant heavier than
air. That means, the heat exchanger, in particular evaporator, exchanges heat form
the air to the refrigerant. The housing is shaped such that it accommodates the evaporator
and guides the air flow passing through the evaporator in a closed air flow region
thereby preventing any possible leakage of flammable refrigerant fluid present in
the evaporator, thereby preventing any possible contact with other components of the
heating device (hot source or with activation energy), e.g. the compressor, that could
trigger an explosion.
[0011] Moreover, this apparatus allows a more accurate reading of the refrigerant temperature,
thereby allowing the expansion valve to close faster and avoid fluid migration when
the system is off. Moving the temperature sensor away from the compressor avoids overheating
of the sensor when the compressor is off, which would open the expansion valve and
encourage the migration of the fluid (rising from the condenser). In particular, this
reduces the pump down time of the compressor.
[0012] In addition, thanks to this apparatus, the heat from the compressor that is lost
during this circuit cooling is recycled and used to warm the air entering the evaporator.
This improves the exchange performance of the evaporator as more energy is available.
[0013] In one example, the temperature sensor is attached to a piping portion containing
the refrigerant flowing from the heat exchanger to the compressor element, and the
housing comprises a piping port for the passage of said piping portion inside the
air flow region. In other words, a portion of the piping containing the refrigerant
is deviated in order to enter and exit the air flow region.
[0014] By circulating part of the refrigerant circuit between the evaporator and the compressor
in the air flow region, the tubes of this piping portion are cooled by convection
and are therefore not affected by the operating temperature of the compressor. Thus,
the temperature read by the sensor in contact with the refrigerant tube of said piping
portion is the temperature of the fluid and is not biased by the temperature relayed
by the compressor. This accurate reading of the refrigerant temperature allows the
heat pump system to operate correctly. Indeed, having the temperature sensor in a
cooler environment prevents the expansion valve to open and to close too frequently
and irrelevantly due to misinterpretation of the state of the system.
[0015] The piping port can be located in a zone delimiting the air flow region, i.e. can
be located between a zone inside the air flow region and a zone outside said air flow
region.
[0016] In another example, the piping portion comprises an inlet piping and an outlet piping,
the temperature sensor being located between the inlet piping and the outlet piping
and the piping port comprises a gasket element for supporting the inlet piping and
the outlet piping. The inlet piping is a section of the piping portion entering the
air flow region, whereas the outlet piping is a section of the piping portion exiting
the air flow region. The piping portion can have a coil shape, wherein the inlet point
of the inlet piping and the outlet point of the outlet piping are close to each other,
in particular are both located to the piping port at the gasket element. Advantageously,
the gasket element comprises two through holes for the passage of the inlet piping
and the outlet piping. It is noted that the gasket element can also serve to seal
the pipe. In that case it is configured to avoid the transmission of vibrations from
the piping. In other words, as the compressor vibrates, the compressor can transmit
vibration to the piping. In this case, abrasion between the piping and the gasket
is preferably to be reduced, in particular avoided. Advantageously, the gasket can
therefore be made of a soft or flexible material. A soft or flexible material in accordance
with the present invention is preferably defined as a material that has a tensile
elongation in elastic behavior of at least 10%. In other words, for the determination
of such an elastic behavior, a tensile stress is applied to the material until it
is elongated by at least 10% and then it has to return to its original length without
deformation. The tensile elongation value is determined according to ISO 1798 and
DIN 53571. A suitable material is for example polyethylene foam. A suitable material,
in particular polyethylene foam, preferably has a Young Modulus between 0 MPa and
100MPa, in particular between 1 MPa and 100 MPa, in particular 5 MPa to 20 MPa. The
values in MPa refer to the Young Modulus determined at 3% compression in dependence
of g/l (gram per liter). The Young Modulus is determined according to ISO 844. Alternatively
or additionally, the interface points between the gasket and the piping can be vibration-damped.
Suitable means for vibration damping can be for example elastomeric rings.
[0017] In an additional example, the housing is shaped to place the temperature sensor in
the air flow region, wherein the air is guided to flow from the air inlet to the heat
exchanger. In this way, overheating of the temperature sensor is avoided.
[0018] In an example, the temperature sensor can be an electronic sensor or a mechanical
sensor. The sensor can be electronically connected to the expansion valve for monitoring
at least one temperature dependent value. The temperature sensor can be a so called
sensing bulb containing a liquid which expands depending on the temperature of the
piping. This bulb is fluidly connected to the expansion valve so that when the temperature
of the bulb rises, the liquid expands and this expansion pushes a part directly into
the expansion valve to close or to open it.
[0019] According to an example, the housing comprises a first component for holding the
heat exchanger and the compressor element connectable to the heating device and a
second component connectable to the heating device to form the air flow region. Advantageously,
the two components are configured to physically separate the heat exchanger and the
temperature sensor located in the air flow region from the compressor element. For
example, the first component can surround, at least partially, the compressor element
and the second component can surround, at least partially, the heat exchanger and
the temperature sensor. It is noted that the both the first component and the second
component can be directly connected to a portion of the heating device or indirectly
connected to a portion of the heating device, i.e., by means of an interposed element.
[0020] In one example, the second component is at least in part fixable to, and removable
from, the first component, the first component and the second component being both
shaped to guide air to flow from the air inlet to the heat exchanger and from the
heat exchanger to the air outlet. Specifically, the first component can be the bottom
component of the housing and the second component can be the top component of the
housing, wherein the first component represents a base on which several elements of
the heating device can be accommodated and/or fixed. For example, the evaporator,
the compressor, the expansion valve and the fan element can be accommodated on the
second component of the housing. The second component is configured to be coupled
to the first component and acts as a sort of cap and is used to separate the evaporator
(and the fan element) from other elements present and arranged on the first component,
such as the compressor. In addition to isolating the evaporator (and the fan element)
from other elements of the heating device, by coupling the first component to the
second component an air flow region is built in order to guide the air flow from the
air inlet to the evaporator and from the evaporator to the air outlet. The first and
second component are specifically shaped to confine air in the air flow region and
to form a preferred path from the air inlet to the air outlet passing through the
evaporator.
[0021] To fluidically isolate the evaporator and the temperature sensor from other elements
of the heating device that could trigger an explosion in case of leakage of the flammable
refrigerant fluid and that could determine an overheating of the sensor, the first
component is connected to the second component to form a connecting region that is
airtight and/or watertight. In this way, the apparatus ensures a good seal between
the evaporator and the heating device, thereby improving the overall performance of
the device. Indeed, if the heating device stops, the outside air penetrates into the
apparatus but is confined in the housing. This apparatus is positioned within the
overall heating device casing, providing two layers of thermal insulation.
[0022] In one example, the first component and the second component are one-piece parts.
This facilitates the manufacturing of these components and strongly reduces the risk
of fluid passage from inside the housing in the air flow region and to outside the
housing (of course with the exception of the air flowing through the air inlet and
air outlet).
[0023] In another example, the first component and the second component are both shaped
to form a first seat, in particular for the placement of the heat exchanger. The first
component comprises a recess where to fix, e.g. to slot in, the base of the evaporator
and the second component comprises an internal concave region to accommodate, at least
in part, the top of the evaporator.
[0024] In an additional example, the first component and the second component are both shaped
to form a second seat, in particular for the placement of a fan element. Similar to
the case of the first seat, the first component can comprise a recess where to fix,
e.g. to slot in, the base of the fan element and the second component can comprise
an internal concave region to accommodate, at least in part, the top of the fan element.
[0025] In a further example, the housing can comprise a base component interposed between
at least the first component and the heating device to fix said first component to
the heating device. In addition or in alternative, the housing can comprise a base
component interposed between at least the second component and the heating device
to fix said second component to the heating device.
[0026] In another example, the first component and the second component form a one-piece
structure.
[0027] In one example, the air inlet and the air outlet are located on the second component
and the heat exchanger and the compressor element are fixable to the first component.
Advantageously, the connection of the first component with the second component produces
a physical separation between the compressor and the evaporator, although they are
both located on the same supporting base, i.e., the first component. Alternatively,
the heat exchanger and the compressor element can be fixable to a base element interposed
between at least the first component and/or the second component, and the heating
device.
[0028] In an example, the apparatus further comprises a condensate drain outlet coupled
to the heat exchanger to evacuate condensate resulting from heat exchange at the heat
exchanger. In this way, the condensate resulting from the heat exchange at the evaporator
can be safely evacuated.
[0029] In case the condensate drain is not properly functioning, i.e., it is obstructed,
the apparatus can further comprise a safety drain outlet located in a bottom region
of the housing to evacuate a fluid from the air flow region to the outside. For example,
the safety drain outlet can be located in the first component of the housing. Accordingly,
even if the condensate drain outlet is blocked by water, the, in particular flammable,
refrigerant fluid will be able to escape through the safety drain outlet. This outlet
is positioned at a low point and far from electronic devices, which ensures that the
fluid will never fill the housing and risk entering the rest of the heating device
environment or go to electronic devices.
[0030] In another example, the air inlet and the air outlet are both located in a top or
lateral region of the housing. In a different configuration, the air inlet can be
located in the top region, whereas the air outlet in the lateral region, or vice versa.
The different location of the air inlet and outlet affects the shape of the housing,
i.e. the shape of the first and second components of the housing in order to form
the air flow region able to efficiently guide the air from the air inlet to the evaporator
and from the evaporator to the air outlet.
[0031] In an further example, in order to make the apparatus compatible with the environment
of the heating device, the housing is made of a polymeric material, in particular
of foam plastic, more particularly of polypropylene expanded (PPE). Specifically,
both the first and the second component are made of polymeric material, in particular
of foam plastic, more particularly of polypropylene expanded (PPE).
[0032] In an additional example, in order to optimize air flow and limit aeraulic disturbances,
an air duct connecting the air inlet to the air outlet comprises a variable cross-section.
In particular, the cross-section of the air duct at the air inlet and at the air outlet
can be different from the cross-section at the heat exchanger, wherein in particular
the cross-section of the air duct at the air inlet and at the air outlet can be circular
or cylindrical and the cross-section at the heat exchanger can be polygonal or angular
shaped. Specifically, the air duct can have a progressive cross-section, for example
increasing from the air inlet to the evaporator and decreasing form the evaporator
to the air outlet.
[0033] In another example, the heating device further comprises at least a fan element,
in particular a brushless fan, arranged inside the air flow region and coupled to
the heat exchanger. In this way, the fan element is accommodated in the housing and,
similarly to the heat exchanger, separated from the other elements of the heating
device. The fan element serves to optimize the flowing of the air in the air flow
region. Advantageously, the fan element can be placed downstream of the evaporator
in the air flow region due to a lower air mass volume of the air. However, the fan
element can also be placed upstream of the evaporator. In this way, it possible to
manage refrigerant leaks at the evaporator regardless of the state of the heating
device. If the fan element is running, the leak will be extracted from the air duct
through the air outlet. If the fan element is off, since the refrigerant fluid is
heavier than air, this fluid can escape through the condensate drain outlet and/or
the safety drain outlet.
[0034] In an example, the air flow region comprises an air flow sub-region located between
the fan element and the heat exchanger, the housing in said air flow sub-region being
shaped to guide air from the heat exchanger to the air outlet. In the air flow sub-region
the first and second components are shaped to form a volute structure to improve the
fan element performances. Also, in this air flow sub-region the first and second components
are shaped to form conduit to improve the air flow guiding from the evaporator to
the fan element.
[0035] According to another example, to increase the safety of the heating device, any ignition
source is arranged outside the air flow circulating region, i.e. outside the housing.
[0036] In an example, at least a portion of the housing is part of the heating device. The
apparatus can be composed of specific parts or can be integrated with parts that are
also used for the structure of the heating device, such as a heat pump base or the
outer casing of the heat pump. In particular, the apparatus can therefore be located
inside the heating device and covered by the casing parts or be part of the casing
itself.
[0037] In another aspect of the invention, a heating device, in particular a heat pump water
heater using a flammable refrigerant, is provided, the heating device comprising the
inventive apparatus. In particular, the heating device comprises at least a heat exchanger,
a compressor element and an expansion valve and a temperature sensor connectable to
the expansion valve for monitoring the temperature of the refrigerant flowing out
the heat exchanger, wherein the heat exchanger and the temperature sensor are located
inside the air flow region in the housing of the apparatus and the compressor element
and the expansion valve are located outside said air flow region in the housing of
the apparatus.
[0038] In one example, the temperature sensor is attached to a piping portion with a material
having a thermal conductivity higher than 1 W/(m*K). Also, the temperature sensor
can be covered by a thermal insulation material, in particular an insulation foam,
wherein in particular the thermal insulation material has a thermal conductivity lower
than 0.1 W/(m*K). In addition, a piping portion on which the temperature sensor is
attached can have a length of at least 5 cm.
[0039] According to a further example, the heating device comprises a capping element configured
to be coupled to a top region of the heating device and covering the housing of the
apparatus, the capping element comprising a first opening coupled to the air inlet
of the housing and a second opening coupled to the air outlet of the housing, wherein
between the first opening and the air inlet and between the second opening and the
air outlet are provided sealing means.
[0040] In a further aspect of the invention, a use of the inventive flow guiding apparatus
is provided. The inventive flow guiding apparatus is used in a heating device, in
particular a heat pump water heater using a flammable refrigerant.
[0041] In the figures, the subject-matter of the invention is schematically shown, wherein
identical or similarly acting elements are usually provided with the same reference
signs.
- Figure 1
- shows a schematic representation of the flow guiding apparatus according to an example.
- Figures 2A-B
- show a perspective view of the apparatus with and without the second component according
to an example.
- Figures 3A-B
- show a perspective view of the apparatus with and without the second component according
to an example.
- Figure 4A-B
- show two perspective views of the temperature sensor attached to the piping portion
according to an example.
- Figures 5A-B
- figure 5A shows a cross-section view and figure 5B shows a perspective view of the
heating device and the capping element according to an example.
Figure 1 illustrates the apparatus 1 for guiding the airflow in a schematic representation.
The apparatus 1 can be coupled to a heating device 2, for example a heat pump water
heater. The heating device 2 comprises at least one heat exchanger such as an evaporator
8 to absorb heat from the air and transfer it to the refrigerant fluid circulating
in said evaporator 8. Thus, the fluid will be able to change from an at least partially
liquid to a gaseous state. The evaporator 8 is crossed by an air circulating path
receiving air from outside. The air can be ambient air or stale air from domestic
rooms via ventilation ducts. The fluid at low pressure is conducted to a compressor
15 coupled to the evaporator 8 and is then directed to another heat exchanger, such
as a condenser (not shown in the figure) for a heat transfer with a water tank 21.
The device 2 comprises also an expansion valve 28 to expand the refrigerant from high
pressure to low pressure, the expansion valve 28 being connected to the evaporator
8 through a piping (not shown in the figure). The expansion valve 28 is electronically
connected to a temperature sensor 29 for monitoring the refrigerant temperature, the
temperature sensor 29 being attached to a portion of the piping connecting the evaporator
8 to the compressor 15 (not shown in the figure. The evaporator 8, the expansion valve
28, and the compressor 15 are located on a top region of the heating device 2 and
the water tank 21 is located in a bottom region of the heating device 2 inside a casing
22. Alternatively, the connection between the expansion valve 28 and the temperature
sensor 29 is not electronic. For example, the connection can be provided by a capillary
piping with fluid which expand inside it depending on the temperature of the sensor/bulb.
[0042] The apparatus 1 comprises a housing 3 having a first component 10 and a second component
11. It is noted that the first component 10 represents a base element on which several
elements of the heating device are arranged. The first component 10 can be fixed to
the top of the casing 22 of the heating device 2. The second component 11 is, on the
other hand, a capping structure that can be fixed to, and removed from, the first
component 10. Alternatively, the first component 10 and the second component 11 could
form a single part. The second component 11 is schematically illustrated in figure
1 with a grey border. It is noted that according to the figure, when the second component
11 is coupled to the first component 10, the second component 11 is not configured
to completely cover/cap the entire surface of the first component 10. As a matter
of fact, when the second component 11 is coupled to the first component 10, an air
flow region 7 is formed and some of the elements arranged on the first component 10,
such as the compressor 15 and the expansion valve 28, are located outside said region
7, whereas other elements, such as the evaporator 8 and the temperature sensor 29
are located inside the air flow region 7. Alternatively, the second component 11 can
completely cover the surface of the first component 10. In this case, the second component
11 could also function as a capping of the heat pump compartment and could comprise
at least two separated closed regions containing the air flow region 7 and the compressor
15 and expansion valve 28, respectively.
[0043] The housing 3 comprises an air inlet 4, an air outlet 5 and an air duct 6 connecting
the air inlet 4 to the air outlet 5. It is noted that the air duct 6 comprises a first
sub-duct comprised between the air inlet 4 and the evaporator 8 and a second sub-duct
comprised between the evaporator 8 and the air outlet 5. Environmental air at a certain
temperature enters the air inlet 4, crosses the evaporator 8, and exits the air outlet
5 at a lower temperature. To improve the air conduction to the air outlet 5, a fan
element 9 is located downstream of the evaporator 8 in the portion of the air duct
6 between the evaporator 8 and the air outlet 5.
[0044] The use of the apparatus 1 in a heating device 2, like a heat pump unit of a thermodynamic
water heater operating with a flammable refrigerant heavier than air, is very useful.
As a matter of fact, the apparatus 1 does not incorporate any ignition source (hot
source or with activation energy). This apparatus 1 has a housing 3 allowing an air
flow to enter and exit the apparatus 1 passing through the evaporator. Since the apparatus
1 is sealed from the rest of the heat pump compartment, it prevents the transfer of
fluids (flammable gas in the event of a leak, water from condensate, air flow, etc.)
to other element that are not in the housing 3. This avoids the risk of ignition in
the event of a gas leak in the circuit contained in housing 3 or rather in the air
flow region 7. It also improves the acoustics of the product thanks to an efficient
and leakage-free airflow control since the noise waves from the operating compressor
15 must pass through surfaces before propagating to the outside of the product, either
through the said compartment to reach the vents, or through the casing of the compressor
15. This also avoids water stagnation and corrosion. As a matter of fact, trenches
and openings are included in the room to allow for fluid flow. This also improves
the performance of the compressor 15 and the product in general as the compressor
15 is not cooled by air from the air vents. In particular, a condensate drain outlet
12 is located between the bottom of the fan space and the evaporator space to allow
for water flow (splash, condensation, etc.). In order to cope with the possibility
of an obstruction of the condensate drain outlet 12, an additional opening, i.e.,
a safety drain outlet 13, is present at a lower level than air outlet 5 and air inlet
4.
[0045] In addition, the position of the temperature sensor 29 in the air flow region 7 prevents
the overheating of said sensor, for example due to the proximity of hot elements,
which may cause convection or heating due to the conductive nature of the copper piping
connected to hot elements, such as the compressor 15.
[0046] The housing 3, i.e., the first component 10 and the second component 11, is made
of a material compatible with this environment and is preferably made of foamed plastic
such as expanded polypropylene.
[0047] Figures 2A-2B and 3A-3B illustrate a perspective view of the apparatus 1 coupled
to a heating device 2, in particular coupled to the top portion of the casing 22 of
the heating device 2. Figures 2A and 2B show a first configuration, wherein the second
component 11 is coupled to the first component 10 (Fig. 2A) and a second configuration,
wherein the second component 11 is removed from the first component 11 (Fig. 2B).
Also in combination with figure 1, it is noted that the second component 11 is a sort
of convex cap suitably shaped to allow the arrangement of elements, such as the evaporator
8, the temperature sensor 29 and fan element 9 (only the corresponding fan seat 24
is shown in the figure) inside the housing 3, and to form an air duct 6 from the air
inlet 4 to the air outlet 5 passing through the evaporator 8. For example, the second
component 11 has an air flow portion 25 at the air inlet 4 and air outlet 5, the air
flow portion 25 having a cylindrical shape. Also, the second component 11 has an evaporator
portion 26 at the evaporator 8, the evaporator portion 26 having a polygonal outline
to allow the arrangement of the upper part of the evaporator 8 that usually has a
parallelepiped form (see figure 2B). Additionally, the second component 11 has a fan
portion 27, having a curved shape to allow the arrangement of the upper part of the
fan 9 that usually has a circular form. In a similar way, the first component 10 is
suitably shaped to allow the arrangement of elements, such as the evaporator 8, the
temperature sensor 29, and fan element 9 inside the housing 3, and to form an air
duct 6 from the air inlet 4 to the air outlet 5 passing through the evaporator 8.
Figure 2B shows for example that the first component 10 is provided with a dedicated
seat (or second seat) 24 for the fan element 9 having a curved shape. An analogous
dedicated seat (or first seat) 23 for the evaporator 8 is also provided in the first
component 10, this seat 23 having a rectangular, polygonal shape (not shown in the
figure). The first seat 23 is a rectangular slot for inserting the lower part of the
evaporator 8. This can be clearly derived for example from figure 3B.
[0048] By comparing figures 2A and 2B, it is noted that when the second component 11 is
removed from the first component 10, different elements of the heating device 2, such
as the evaporator 8, the temperature sensor 29, the expansion valve 28, and the compressor
15 are located in the same environment. In other words, air flowing through the evaporator
8 could also pass close to the compressor 15. This is basically the standard situation
described in prior art. On the other hand, when the second component 11 is coupled
to the first component 10, the evaporator 8 and the temperature sensor 29 are separated
from the compressor 15 and the expansion valve 28. The walls of the second component
11 prevent air flowing in the air duct 6 from the air inlet 4 to the air outlet 5
to be in contact with the compressor 15 and to prevent the temperature sensor 29 to
be in a overheating environment.
[0049] Figure 3A illustrates in detail the coupling of the second component 11 to the first
component 10 and the arrangement of elements, such as the evaporator 8, the temperature
sensor 29, the piping portion 30 on which the temperature sensor 29 is attached, and
the fan element 9, inside the housing 3 in the air flow region 7. To better appreciate
the location of the evaporator 8, the temperature sensor 29, the piping portion 30,
and the fan element 9, the second component 11 is sketched with a transparency grade.
[0050] Figure 3B shows in a top view the evaporator 8 with the temperature sensor 29 on
the first component 10 and the second seat 24 dedicated for arranging the fan element
9. An air flow sub-region 16 is located between the evaporator, in particular the
first seat 23, and the second seat 24. In this airflow sub-region 16, the housing
3, and in particular the first component 10 and second component 11 are shaped to
guide air from the evaporator 8 to the air outlet 5. In the air flow sub-region 16
the first and second components 10, 11 are shaped to form a volute structure to improve
the performances of the fan element 9. Also, in this air flow sub-region 16 the first
and second components 10, 11 are shaped to form conduit to improve the air flow guiding
from the evaporator 8 to the fan element 9.
[0051] Figure 3B also shows a connection region 14, represented with a dotted line in the
figure, this region 14 being the contact portion between the first component 10 and
the second component 11. In other words, the connection region 14 is the external
border of the air flow region 7 and defines the outline inside which the elements
(e.g. the evaporator 8, temperature sensor 29, piping portion 30, the fan element
9) are confined in the air flow region 7. At the connection region 14, the housing
3 is water-sealed and air-sealed from the rest of the heat pump compartment.
[0052] Figures 4A and 4B illustrate the arrangement of the temperature sensor 29 relative
to the evaporator 8, the compressor 15 and the expansion valve 28, without the first
component 10 and the second component 11 of the flow guiding apparatus 1. It is noted
that the piping containing the refrigerant has a piping portion 30 that deviates from
a linear path 36 in order to create an additional path close to a surface of the evaporator
8. As explained above and as shown in Fig. 3A, the deviation serves to place the piping
portion 30 in the air flow region 7. A piping port 31 in the form of a gasket element
34 delimits the internal area from the external area of the air flow region 7. The
gasket element 34 has two through holes for the passage of the inlet piping 32 (containing
the refrigerant flowing out the evaporator 8) and the outlet piping 33 (containing
the refrigerant flowing to the compressor element 15). To save space, the piping portion
30 has a curved section so that the inlet piping 32 and the outlet piping 33 are parallel
and the inlet and outlet point are located in the same area at the piping port 31.
The temperature sensor 29 is attached to the piping portion 30 between the inlet piping
32 and the outlet piping 33. In particular, the temperature sensor 29 is attached
with a material having a high thermal conductivity (for example > 1 W/(m*K)). The
assembly formed by temperature sensor 29 and the attaching material having a high
thermal conductivity is covered with an insulation preventing direct impact of the
air flow (for example with a therma conductivity lower than 0.1 W/(m*K)). The temperature
sensor 29 is a sensing bulb containing a liquid which expands depending on the temperature
of the piping. As shown in figure 4B, this bulb 29 is connected to the expansion valve
28 by a capillary piping 37 so that when the temperature of the bulb 29 rises, the
liquid expands and this expansion pushes a part directly into the expansion valve
28 to close or to open it. The capillary piping 37 is illustrated in the figure with
an arrowed path flowing out of the temperature sensor 29.
[0053] Figure 5A shows the presence of a capping element 17 that can be coupled to the upper
portion of the casing 22 of the heating device 2. The capping element 17 basically
covers the elements of the top of the casing 22, thereby also covering the apparatus
1, i.e., the first component 10 and the second component 11. The capping element 17
comprises a first opening 18 coupled to the air inlet 4 and a second opening 19 coupled
to the air outlet 5. Figure 5A shows a sliced cross-section of the heating device
2 including the apparatus 1. The figure basically shows the presence of the first
and second components 10, 11 without the evaporator 8, temperature sensor 29 and the
fan element 9. It is noted that the second component 11 is connected to the first
component 10 through a joint mechanism made of recessing and protruding elements and
that below the first component 10 there is a lower region 35 where to arrange the
condenser and the water tank (not shown in the figure). Figure 5B shows a bottom view
of the cap element 17. It is noted that the first and second openings 18, 19 are provided
with sealing means 20 for determining a sealed coupling with the air inlet 4 and air
outlet 5 of the flow guiding apparatus 1.
Reference Signs
[0054]
- 1
- Flow guiding apparatus
- 2
- Heating device
- 3
- Housing
- 4
- Air inlet
- 5
- Air outlet
- 6
- Air duct
- 7
- Air flow region
- 8
- Heat exchanger
- 9
- Fan element
- 10
- First component
- 11
- Second component
- 12
- Condensate drain outlet
- 13
- Safety drain outlet
- 14
- Connecting region
- 15
- Compressor element
- 16
- Air flow sub-region
- 17
- Capping element
- 18
- First opening
- 19
- Second opening
- 20
- Sealing means
- 21
- Water tank
- 22
- Casing
- 23
- First seat
- 24
- Second seat
- 25
- Air flow portion
- 26
- Evaporator portion
- 27
- Fan portion
- 28
- Expansion valve
- 29
- Temperature sensor
- 30
- Piping portion
- 31
- Piping port
- 32
- Inlet piping
- 33
- Outlet piping
- 34
- Gasket element
- 35
- Lower portion
- 36
- Linear path
- 37
- Capillary piping
1. Flow guiding apparatus (1) for a heating device (2), in particular an air-source heat
pump water heater using a flammable refrigerant, the heating device (2) including
at least a heat exchanger (8), a compressor element (15), an expansion valve (28)
and a temperature sensor (29) connectable to the expansion valve (28) for monitoring
the temperature of the refrigerant flowing out the heat exchanger (8), the apparatus
(1) comprising:
a housing (3) couplable to a casing of the heating device (2) and comprising an air
inlet (4) and an air outlet (5), the housing (3) defining an airflow region (7),
wherein the housing (3) is configured so that the heat exchanger (8) is arranged inside
the air flow region (7) for exchanging heat in said air flow region (7), and so that
air is guided to flow from the air inlet (4) to the heat exchanger (8) and from the
heat exchanger (8) to the air outlet (5), the air being confined in the air flow region
(7) and being prevented from being in contact with the compressor element (15) and
the expansion valve (28) that are arranged outside the air flow region (7), and
wherein the housing (3) is shaped to place in the air flow region (7) the temperature
sensor (29) connectable to the expansion valve (29).
2. Apparatus (1) according to claim 1, characterized in that the temperature sensor (29) is attached to a piping portion (30) containing the refrigerant
flowing from the heat exchanger (8) to the compressor element (15), and the housing
(3) comprises a piping port (31) for the passage of said piping portion (30) inside
the air flow region (7).
3. Apparatus (1) according to claim 2, characterized in that the piping portion (30) comprises an inlet piping (32) and an outlet piping (33),
the temperature sensor (29) being located between the inlet piping (32) and the outlet
piping (33) and the piping port (31) comprises a gasket element (34) for supporting
the inlet piping (32) and the outlet piping (33).
4. Apparatus (1) according to any one of claims 1 to 3,
characterized in that
a. the housing (3) is shaped to place the temperature sensor (29) in the air flow
region (7) wherein the air is guided to flow from the air inlet (4) to the heat exchanger
(8); and/or
b. the temperature sensor (29) is an electronic sensor or a mechanical sensor.
5. Apparatus (1) according to any one of claims 1 to 4, characterized in that the housing (3) comprises a first component (10) for holding the heat exchanger (8)
and the compressor element (15) connectable to the heating device (2) and a second
component (11) connectable to the heating device (2), to form the air flow region
(7).
6. Apparatus (1) according to claim 5,
characterized in that
a. the second component (11) is at least in part fixable to, and removable from, the
first component (10), the first component (10) and the second component (11) being
both shaped to guide air to flow from the air inlet (4) to the heat exchanger (8)
and from the heat exchanger (8) to the air outlet (5); and/or
b. the first component (10) is connected to the second component (11) to form a connecting
region (14) that is airtight and/or watertight; and/or
c. the first component (10) and the second component (11) are one-piece parts; and/or
d. the first component (10) and the second component (11) are both shaped to form
a first seat (23), in particular for the placement of the heat exchanger (8); and/or
e. the first component (10) and the second component (11) are both shaped to form
a second seat (24), in particular for the placement of a fan element (9); and/or
f. the housing (3) comprises a base component interposed between at least the first
component (10) and the heating device (2) to fix said first component (10) to the
heating device (2); and/or
g. the housing (3) comprises a base component interposed between at least the second
component (11) and the heating device (2) to fix said second component (11) to the
heating device (2); and/or
h. the first component (10) and the second component (11) form a one-piece structure.
7. Apparatus (1) according to any one of claims 5 to 6, characterized in that the air inlet (4) and the air outlet (5) are located on the second component (11)
and/or the heat exchanger (8) and the compressor element (15) are fixable to the first
component (10) or to a base element interposed between at least the first component
(10) and/or the second component (11), and the heating device (2).
8. Apparatus (1) according to any one of claims 1 to 7,
characterized in that a. the apparatus (1) further comprises a condensate drain outlet (12) coupled to
the heat exchanger (8) to evacuate condensate resulting from heat exchange at the
heat exchanger (8); and/or
b. the apparatus (1) further comprises a safety drain outlet (13) located in a bottom
region of the housing (3) to evacuate a fluid, in particular the flammable refrigerant,
from the air flow region (7) to the outside; and/or
c. the air inlet (4) and the air outlet (5) are both located in a top or lateral region
of the housing (3); and/or
d. the housing (3) is made of a polymeric material, in particular of foam plastic,
more particularly of polypropylene expanded (PPE).
9. Apparatus (1) according to any one of claims 1 to 8, characterized in that an air duct (6) connecting the air inlet (4) to the air outlet (5) comprises a variable
cross-section, wherein in particular the cross-section of the air duct (6) at the
air inlet (4) and at the air outlet (5) is different from the cross-section at the
heat exchanger (8), wherein in particular the cross-section of the air duct (6) at
the air inlet (4) and at the air outlet (5) is circular and the cross-section at the
heat exchanger (8) is polygonal.
10. Apparatus (1) according to any one of claims 1 to 9, characterized in that the heating device (2) further comprises at least a fan element (9), in particular
a brushless fan, arranged inside the air flow region (7) and coupled to the heat exchanger
(8), wherein in particular the air flow region (7) comprises an air flow sub-region
(16) located between the fan element (9) and the heat exchanger (8), the housing (3)
in said air flow sub-region (16) being shaped to guide air from the heat exchanger
(8) to the air outlet (5).
11. Apparatus (1) according to any one of claims 1 to 10,
characterized in that
a. any ignition source is arranged outside the air flow region (7) and/or
b. at least a portion of the housing (3) is part of the heating device (2).
12. Heating device (2), in particular a heat pump water heater using a flammable refrigerant,
comprising the apparatus (1) according to any one of clams 1 to 11, the heating device
(2) comprising at least a heat exchanger (8), a compressor element (15) and an expansion
valve (28) and a temperature sensor (29) connectable to the expansion valve (28) for
monitoring the temperature of the refrigerant flowing out the heat exchanger (8),
wherein the heat exchanger (8) and the temperature sensor (29) are located inside
the air flow region (7) in the housing (3) of the apparatus (1) and the compressor
element (15) and the expansion valve (28) are located outside said air flow region
(7) in the housing (3) of the apparatus (1).
13. Heating device (2) according to claim 12,
characterized in that
a. the temperature sensor (29) is attached to a piping portion (30) with a material
having a thermal conductivity higher than 1 W/(m*K); and/or
b. temperature sensor (29) is covered by a thermal insulation material, in particular
an insulation foam, wherein in particular the thermal insulation material has a thermal
conductivity lower than 0.1 W/(m*K); and/or
c. a piping portion (30) on which the temperature sensor (29) is attached has a length
of at least 5 cm.
14. Heating device (2) according to one of claims claim 12 to 13, further comprising a
capping element (17) configured to be coupled to a top region of the heating device
(2) and covering the housing (3) of the apparatus (1), the capping element (17) comprising
a first opening (18) coupled to the air inlet (4) of the housing (3) and a second
opening (19) coupled to the air outlet (5) of the housing (3), wherein between the
first opening (18) and the air inlet (4) and between the second opening (19) and the
air outlet (5) are provided sealing means (20).
15. Use of the flow guiding apparatus (1) according to one of clams 1 to 11 in a heating
device (2), in particular an air-source heat pump water heater using a flammable refrigerant.