Volumetric body for heat pump unit

Abstract

There is provided a volumetric body for a heat pump unit operable with a refrigerant. The volumetric body houses at least part of a refrigerant circuit of the heat pump unit. When the volumetric body is installed in an operation position, the volumetric body is defined by a bottom wall, a top wall and a side wall of the volumetric body and is a gas-tight volumetric body except for a first opening and a second opening. The first opening is provided in one of the bottom wall, the top wall and the side wall. The second opening is provided in one of the bottom wall, the top wall and the side wall. The first opening and the second opening are configured for gaseous communication between an inside and an outside of the volumetric body. A first distance from the first opening to the bottom wall is equal to or larger than a second distance from the second opening to the bottom wall.

Description

Field of the Invention

[0001] The invention relates to a volumetric body for a heat pump unit operable with a refrigerant, to a heat pump unit comprising the volumetric body, to a use of the volumetric body and to a use of the heat pump unit.Background

[0002] In the event of a leak in a refrigerant circuit of a heat pump unit configured to be installed indoors, flammable refrigerant like R290 for example can flow to the indoor installation space or within the interior of the outer casing of the heat pump unit. In more detail, the leaking flammable refrigerant can flow to the indoor installation space in an uncontrolled manner and be exhausted to the indoor installation space at an insufficient height, resulting in a risk of a concentration of flammable refrigerant potentially causing inflammation. Alternatively or additionally, the leaking flammable refrigerant can flow within the interior of the outer casing of the heat pump unit and get into contact with potential ignition sources present in the heat pump unit, such as a Printed Circuit Board (PCB), the compressor inverter driver, and other electronic components which generate heat, resulting in a risk of fire in case the refrigerant concentration level reaches between the Lower Flammability Limit (LFL) and Upper Flammability Limit (UFL) at the location of the potential ignition source.

[0003] Nowadays, a solution that is often used to reduce the risks of leaking refrigerants, in particular of leaking flammable refrigerants, is the application of a sealed or gastight frigorific box. The sealed or gastight frigorific box houses at least part of the heat pump unit's refrigerant circuit, in particular at least such part where a leakage may be most likely. Due to the frigorific box being sealed or gastight, it is avoided that a leaking refrigerant flows out of the frigorific box in an uncontrolled manner.

[0004] In the event of a leak in a refrigerant circuit of a heat pump unit configured to be installed indoors and in case the heat pump refrigerant circuit contains more than 152 grams of R290, this leaked R290 must be exhausted outdoors as too high refrigerant concentrations could lead to a dangerous situation. To this extent, the heat pump unit must feature mechanical ventilation such that a minimum exhaust air flow rate Q min be reached at an under pressure of 20 Pa or more of the interior of the frigorific box relative to the indoor installation room. The minimum air flow rate, Q min , is computed using formulas GG.16 and GG.17 of Annex GG.4 of standard IEC 60335-2-40:2022 EXV. It shall be noted that if the heat pump unit comprising the more than 152 grams of R290 would be installed outdoors, leaking flammable refrigerant would diffuse in outdoor air resulting in a lower probability that the refrigerant concentration level would reach between the LFL and UFL at the location of the potential ignition source, and would result in a risk of fire. So, instead of using an exhaust fan, an alternative solution would be to only allow installation of a heat pump unit comprising the more than 152 grams of R290 outdoors.

[0005] To reduce the potential formation of a flammable concentration region, especially in small indoor spaces, the leaking flammable refrigerant is diluted. Such dilution process can be achieved by defining a required minimum exhaust height, which may depend on the available floorspace of the indoor space and the amount of flammable refrigerant used in the refrigerant circuit of the heat pump. Further, the leaking refrigerant usually is exhausted by means of a single exhaust opening.

[0006] However, the application of such single exhaust opening may lead to problems, for example if the exhaust path is clogged due to pollution, dust, or the like. Further, the application of a minimum exhaust height might face difficulties for proper dilution as the leaking refrigerant may not be efficiently drawn upward and expelled considering flammable refrigerants are denser than air.

[0007] Hence, there is room and need for improvement regarding the reduction of risks of flammable refrigerants leaking from a heat pump unit's refrigerant circuit.Summary

[0008] In view of the above, it is an object of the present disclosure to overcome at least part of the drawbacks available regarding the reduction of risks of flammable refrigerants leaking from a heat pump unit's refrigerant circuit. It shall be noted that throughout the present disclosure, a heat pump or heat pump unit may be a ground source heat pump using the ground as heat source or a water source heat pump using water as heat source or an air source heat pump using the air as heat source for example.

[0009] Therefore, to address one or more of these drawbacks, there is provided, in a first aspect, a volumetric body for a heat pump unit operable with a flammable refrigerant, wherein the volumetric body houses at least part of a refrigerant circuit of the heat pump unit. When the volumetric body is installed in an operation position, the volumetric body is defined by a bottom wall, a top wall and a side wall of the volumetric body and is a gas-tight volumetric body except for a first opening and a second opening. The first opening is provided in one of the bottom wall, the top wall and the side wall. The second opening is provided in one of the bottom wall, the top wall and the side wall. The first opening and the second opening are configured for gaseous communication between an inside and an outside of the volumetric body. A first distance from the first opening to the bottom wall is equal to or larger than a second distance from the second opening to the bottom wall. For reasons of understandability, it shall be noted that the volumetric body may be understood as the frigorific box (of the heat pump unit), i.e. the volumetric body is not the heat pump unit itself. Moreover, the first opening and the second opening are configured for discharging flammable refrigerant to an outside of the volumetric body in case of a flammable refrigerant leak inside the volumetric body. Hence, it may be said that one or both of the openings may discharge the flammable refrigerant to an outside of the volumetric body in case of the flammable refrigerant leaking inside the volumetric body.

[0010] The term "gas-tight" may also be understood as meaning "sealed". Moreover, for reasons of understandability, the term "gas-tight" or "sealed" in accordance with the present disclosure is not necessarily to be understood as excluding any openings, as outlined below in more detail. Hence, a cumulation of all openings in the gas-tight volumetric body, other than the first and second openings, may be smaller than 5 cm 2< . In this context, the "openings" may be understood as openings communicating the interior of the gas-tight volumetric body with an exterior environment or exterior space of the gas-tight volumetric body. Further, a single dimension, such as the diameter, of such an opening considered in the cumulation is more than 0.1 mm. Accordingly, openings having a dimension, such as a diameter, smaller than 0.1 mm are not considered as openings where leaking refrigerant can escape".

[0011] The term flammable is used with reference to the ASHRAE standards for refrigerants and EN 378-2:2016, defining the following classes: 1, 2L, 2, or 3, ranging from no flame propagation to high flame propagation and high heat of combustion.

[0012] The term flammable is used to refer to refrigerants that are highly flammable, class 3, such as R290 (propane), R600 (butane) and R600a (isobutane). Class 3 refrigerants, when tested, exhibit flame propagation at 140°F (60°C) and 14.7 psi (101.3 kPa) and that either has a heat of combustion of 19,000 kJ / kg (8,174 BTU / Ib) or greater or an LFL of 0.10 kg / m 3< or lower.

[0013] The term flammable may also be used here to refer to refrigerants from class 2 (flammable), such as R-152a or class 2L (mildly flammable) such as R-32, R-1234yf, R-1234ze, R-454C, R-454B.

[0014] Moreover, the volumetric body may be of any shape, and it shall be noted that the volumetric body is not sealed because there are two release openings, i.e. the first opening and the second opening. Said in other words, gas may flow into the volumetric body and / or out of the volumetric body through at least one of the first opening and the second opening. For explanation purposes, it shall be noted that an arrangement of the first opening and of the second opening is not limited to these openings being identical in shape and / or being arranged directly one above the other. Said in other words, in a cartesian coordinate system comprising the x-axis, y-axis and z-axis, in case the bottom wall is seen as an x-y-plane and in case the top wall is seen as being spaced apart from the bottom wall along the z-axis, the first opening and the second opening, in case they have different z-coordinates, do not need to have the same x-y-coordinates. Said in other words, it may be said that the first opening is farther away from the bottom wall as the second opening for example. However, in general, the first and second openings can be located anywhere on the walls of the volumetric body, i.e. on the top wall, on the bottom wall or on one or more side walls. For example, one or both of the first and second openings may be located on the top wall, on the bottom wall or on one or more side walls.

[0015] The term "wall" as used herein may be understood as being elements to define a shape of the volumetric body and / or an inner volume of the volumetric body. A wall may also be understood as representing one or more panels.

[0016] Furthermore, the volumetric body may be understood to represent a non-gastight volumetric body that accommodates at least a potential leaking point of a heat pump unit's refrigerant circuit. Potential leaking points of a heat pump unit's refrigerant circuit may be, for example, the compressor, the utilization-side heat exchanger, the heat-source-side heat exchanger, the expansion device, the filter drier, brazing surfaces, the sight glass, a four-way valve, an oil separator, temperature and / or pressure gauges, the liquid receiver and suction accumulator, and the refrigerant piping.

[0017] The term "expansion device" is to be interpreted broadly throughout the present disclosure to include an expansion valve that may be of the electronic or thermostatic type and to also cover a capillary tube, or the like facilitating the expansion of compressed refrigerant within the refrigerant circuit.

[0018] The term "equal to" comprises that the first and second openings may both be arranged in the top wall or the bottom wall.

[0019] Moreover, regarding the first and second openings, it should be noted that the first and second openings are not to be understood as openings for e.g., condensate draining, 0-50V communication, main 230 V power supply, means for transportation for example lifting, etc. Rather, the first and second openings may be understood as being independent and to have a distinct aperture. The openings are to be understood based on their physical features (distinct apertures) rather than on their functional characteristics (distinct flow pathways within a single opening).

[0020] The volumetric body is advantageous in several ways. For example, in the event of a leakage in the refrigerant circuit, the volumetric body allows that a flow of potentially flammable refrigerant (e.g., R290) can be safely exhausted to an outside of the volumetric body through at least one of the first opening and the second opening. In more detail, the flow of potentially flammable refrigerant can be safely exhausted to an exterior of an outer casing of the heat pump unit, via at least one of the first opening and the second opening. The volumetric body hampers a flow of potentially flammable refrigerant (e.g., R290) over potential ignition sources, thereby reducing the risk of ignition of the potentially flammable refrigerant. Moreover, the first opening and the second opening allow to create a fluid circulation through the volumetric body. Fresh air may enter the volumetric body at least through the first opening (i.e. the top opening) for example and may leave through the second opening (i.e. the bottom opening). The fresh air could come from an interior of a building in which the heat pump unit is installed and / or from an outdoor environment (for example an environment outside the building) to which leaked refrigerant can be exhausted. In general, fresh air could enter and / or exit through both openings. Such flow through the volumetric body is enabled through natural convection and / or forced convection for example. The driving factor for natural convection flow may be a density difference induced by a temperature gradient. For example, the gas inside of the volumetric body may be warmer than the fresh air entering the volumetric body. Additionally or alternatively, the driving factor for natural convection flow may be a density difference induced by a concentration gradient. The driving factor for forced convection may be the use of a fan or a blower.

[0021] According to several examples of the present disclosure, the volumetric body may be of a cylindrical shape and the side wall may be the curved surface area of the cylinder.

[0022] According to several examples of the present disclosure, the volumetric body may be of a prism or prismatic shape, wherein the bottom wall may represent a bottom face, wherein the top wall may represent a top face, and wherein the side wall may comprise a plurality of side faces that are side faces of the prism or prismatic shape, and wherein the first opening and the second opening are arranged at a same face. Alternatively, for reasons of understandability, the first opening and the second opening may be arranged at different faces. Moreover, the prism shape may be a cuboid shape for example.

[0023] For example, the volumetric body may be of a box or cuboid shape that has a bottom face, a top face and four side faces that form the side wall. A side face of the side wall may be understood as a panel that forms at least part of the side wall.

[0024] The first and second opening in the volumetric body, along with the corresponding openings in the heat pump unit's casing (which accommodates the volumetric body), may be positioned such that each opening in the volumetric body aligns with an opening in the heat pump unit's casing. These openings may be arranged either on the same face or on two perpendicular faces. Due to this arrangement, a direct gaseous communication path between the inside of the volumetric body and the outside of the heat pump unit is realized which simultaneously facilitates the dilution of the leaked flammable refrigerant by means of air from the indoor and / or outdoor environment and the exhaust of leaked flammable refrigerant avoiding interaction with potential ignition sources. Further, in such case, an installation of the volumetric body in the heat pump unit is made easier.

[0025] According to several examples of the present disclosure, the volumetric body may be of a cuboid shape, wherein the bottom wall may represent a bottom face, wherein the top wall may represent a top face, and wherein the side wall may comprise a plurality of side faces that are side faces of the cuboid shape, and wherein the first opening and the second opening are arranged at different faces.

[0026] Due to the first opening and the second opening being arranged at different faces, an efficiency of the ventilation of the gas through the inside of the volumetric body may be improved. In particular, improved ventilation is achieved and there is a lower concentration of flammable refrigerant inside the heat pump unit. This is what Computational Fluid Dynamics simulation results show.

[0027] According to several examples of the present disclosure, the first distance may be a smallest distance from the first opening to the bottom wall, and the second distance may be a largest distance from the second opening to the bottom wall.

[0028] Said in other words, it may be said that the first opening is arranged higher than the second opening, and that the first opening and the second opening do not overlap at a same height.

[0029] Due to the first opening and the second opening being arranged at different heights, an efficiency of the ventilation of the gas through the inside of the volumetric body is improved.

[0030] According to several examples of the present disclosure, a third distance, which is the first distance subtracted by the second distance, may be in a range between 1 cm to 75 cm.

[0031] Due to such third distance between the first opening and the second opening, a ventilation through the volumetric body is ensured.

[0032] According to several examples of the present disclosure, a fourth distance is a smallest distance from the second opening to the bottom wall, and wherein the fourth distance may be in a range between 0 cm, so that a portion of the edge of the second opening may form at least part of the edge of the bottom wall (111), and 75 cm.

[0033] In case the fourth distance is zero so that a portion of the edge of the second opening forms part of the edge of the bottom wall, leaking gas may easily and quickly flow out of the volumetric body through the second opening.

[0034] In case the fourth distance is greater than zero, leaking gas may accumulate inside the volumetric body which, in a first step, may at least reduce a direct emission of the gas to an indoor installation space in which the heat pump unit is installed for example. A sensor (e.g. as part of a leak detection system) may detect the leaking gas and may trigger a fan for blowing the gas out of the volumetric body for example. Additionally or alternatively, a fan may be used to exhaust the leaking gas continuously, other than for short periods for maintenance and service.

[0035] According to several examples of the present disclosure, the first opening may have a minimum cross-sectional area of at least 500 mm 2< , the second opening may have a minimum cross-sectional area of at least 500 mm 2< .

[0036] It shall be noted that the first opening and the second opening may be of any shape. The first opening and the second opening may be of a same shape. The first opening and the second opening may be of different shapes.

[0037] Due to these minimum cross-sectional areas, a minimum flow rate is enabled that allows for reliably guiding leaking gas out of the volumetric body.

[0038] According to several examples of the present disclosure, the volumetric body may further comprise a fan for promoting gaseous flow out of and / or into the volumetric body through at least one of the first opening and the second opening. The fan may be of the explosion-proof type.

[0039] It shall be noted that the fan may be configured to run continuously for blowing gas out of the first opening, if the fan is arranged at the first opening, or for blowing gas out of the second opening, if the fan is arranged at the second opening. For example, the fan may run continuously. Alternatively, according to several examples of the present disclosure, the volumetric body may further comprise a sensor arranged inside the volumetric body. The sensor may be configured to detect leaking gas. Further, the sensor may be configured to trigger the fan for blowing detected gas out of the volumetric body.

[0040] Hence, even greater amounts of leaking gas may be blown out of the volumetric body more reliably.

[0041] According to several examples of the present disclosure, the volumetric body may have a pressure difference between an inside and an outside of the volumetric body equal to a pressure difference in the range of 20 Pa - 100 Pa, preferably 30 Pa.

[0042] According to several examples of the present disclosure, the volumetric body may be a frigorific box housing at least part of the refrigerant circuit of the heat pump unit.

[0043] Moreover, according to a second aspect, there is provided a heat pump unit operable with a flammable refrigerant. The heat pump unit comprises a housing, a refrigerant circuit, and volumetric body according to the first aspect that is installed inside the housing. The housing houses the refrigerant circuit and the volumetric body. The volumetric body houses at least part of the refrigerant circuit. When the heat pump unit is installed in an operation position, the housing of the heat pump unit comprises a housing bottom wall, a housing top wall and a housing side wall. The housing comprises a first heat pump unit opening and a second heat pump unit opening. The first heat pump unit opening is provided in one of the housing bottom wall, the housing top wall and the housing side wall. The second heat pump unit opening is provided in one of the housing bottom wall, the housing top wall and the housing side wall. The first heat pump unit opening and the second heat pump unit opening are configured for gaseous communication between an inside and an outside of the heat pump unit. The first heat pump unit opening is in gaseous communication with the first opening of the volumetric body, and the second heat pump unit opening is in gaseous communication with the second opening of the volumetric body.

[0044] The housing of the heat pump unit may be understood as an outer casing of the heat pump unit. The first heat pump unit opening and the second heat pump unit opening may be arranged at a different housing face.

[0045] The volumetric body is advantageous in several ways. For example, gas from inside the volumetric body may be efficiently guided toward outside of the housing, i.e. toward an indoor installation environment and / or toward the outdoors, i.e. the outdoors of the indoor installation environment. Thus, a spreading of the gas inside the housing is hampered.

[0046] According to several examples of the present disclosure, the first heat pump unit opening may be connected to the first opening of the volumetric body, so that gas flowing into and / or out of the volumetric body through the first opening enters and / or exits the housing via the first heat pump unit opening. The second heat pump unit opening may be connected to the second opening of the volumetric body, so that gas flowing out of and / or into the volumetric body through the second opening exits and / or enters the housing via the second heat pump unit opening.

[0047] Hence, gas from inside the volumetric body may be guided even more efficiently toward outside of the housing, i.e. toward an indoor installation environment and / or toward the outdoors, i.e. the outdoors of the indoor installation environment. Thus, a spreading of the gas inside the housing is even further hampered.

[0048] According to several examples of the present disclosure, the housing bottom wall may represent a housing bottom face, the housing top wall may represent a housing top face, and the housing side wall may comprise a plurality of housing side faces. The first heat pump unit opening and the second heat pump unit opening may be arranged at a same housing face. The first heat pump unit opening and the second heat pump unit opening may be arranged to match or overlap the first opening and the second opening respectively.

[0049] According to several examples of the present disclosure, a distance between the side wall of the volumetric body and the housing side wall is at least 5 mm. An acoustic insulation element may be placed between the side wall of the volumetric body and the housing side wall.

[0050] Hence, it is avoided that the side wall of the volumetric body, when vibrating for example, is in contact with the housing side wall. Thus, it may be avoided that vibrations caused by the compressor inside the volumetric body affect the housing (i.e. the housing side wall). Therefore, such acoustic decoupling contributes to attenuate noise emission.

[0051] According to several examples of the present disclosure, the heat pump unit may further comprise a ventilation duct connected to the second heat pump unit opening for gas to flow out of the volumetric body into the ventilation duct through the second heat pump unit opening. Wherein one of the following three alternatives a), b) or c) may be provided: a) The ventilation duct is a regular pipe, a fan is provided in the second heat pump unit opening, and gas flows from a space outside of the heat pump unit and inside an installation space of the heat pump unit into the volumetric body through the first heat pump unit opening. b) The ventilation duct is surrounded by a concentric pipe that is not connected to the second heat pump unit opening but opens to a space outside of the heat pump unit and inside an installation space of the heat pump unit, a fan is provided in the second heat pump unit opening, gas flows from a space outside the installation space of the heat pump unit through the concentric pipe into the space outside of the heat pump unit and inside the installation space of the heat pump unit, and gas flows from the space outside of the heat pump unit and inside the installation space of the heat pump unit into the volumetric body through the first heat pump unit opening. c) The ventilation duct is surrounded by a concentric pipe that is connected to the second heat pump unit opening, a fan is provided in the second heat pump unit opening, gas flows from a space outside the installation space of the heat pump unit through the concentric pipe into the volumetric body through the second heat pump unit opening, and gas flows from the space outside of the heat pump unit and inside the installation space of the heat pump unit into the volumetric body through the first heat pump unit opening.

[0052] Furthermore, according to a third aspect, there is provided a use of the volumetric body according to the first aspect.

[0053] Further, according to a fourth aspect, there is provided a use of the heat pump unit according to the second aspect.

[0054] Optional features of the first aspect and / or the second aspect may form part of any of the third and fourth aspects, mutatis mutandis.

[0055] The indefinite article "a" or "an" does not exclude a plurality. In addition, the articles "a" and "an" as used herein should generally be construed to mean "one or more" unless specified otherwise or clear from the context to be directed to a singular form.

[0056] Unless specified otherwise, or clear from the context, the phrases "one or more of A, B and C", "at least one of A, B, and C", and "A, B and / or C" as used herein are intended to mean all possible permutations of one or more of the listed items. That is, the phrase "A and / or B" means (A), (B), or (A and B), while the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0057] The term "comprising" does not exclude other elements or steps. Furthermore, the terms "comprising", "including", "having" and the like may be used interchangeably herein.

[0058] The invention may include one or more aspects, examples or features in isolation or combination whether specifically disclosed in that combination or in isolation. Any optional feature or sub-aspect of one of the above aspects applies as appropriate to any of the other aspects.

[0059] The above-described aspects will become apparent from, and elucidated with, reference to the detailed description provided hereinafter.Brief Description of the Drawings

[0060] A detailed description will now be given, by way of example only, with reference to the accompanying drawings, in which: Figure 1 schematically illustrates a volumetric body arranged inside an empty casing of a heat pump unit according to several examples of the present disclosure; Figure 2 illustrates in a three-dimensional view a volumetric body spaced apart from a casing of a heat pump unit according to several examples of the present disclosure; Figure 3 illustrates in a three-dimensional view the volumetric body of Figure 2 arranged inside the empty casing of the heat pump unit of Figure 2 according to several examples of the present disclosure; Figure 4 illustrates the volumetric body of Figure 2 arranged in the heat pump unit according to several examples of the present disclosure; Figure 5 illustrates an example for an arrangement of components of the heat pump unit's refrigerant circuit inside the volumetric body of Figure 4 according to several examples of the present disclosure; Figure 6 illustrates openings in the volumetric body of Figure 4 for control and / or operational purposes 4 according to several examples of the present disclosure; Figure 7 illustrates two release openings in the volumetric body of Figure 4 according to several examples of the present disclosure; Figure 8 illustrates one of the two release openings as shown in Figure 7 in more detail according to several examples of the present disclosure; Figures 9 and 10 illustrate different examples for arrangements in the two release openings as shown in Figure 7 according to several examples of the present disclosure; Figure 11 illustrates a first ventilation ducting design concept according to several examples of the present disclosure; Figure 12 illustrates a second ventilation ducting design concept according to several examples of the present disclosure; and Figure 13 illustrates a third ventilation ducting design concept according to several examples of the present disclosure. Detailed Description

[0061] According to several examples of the present disclosure, there is described a design of a non-gastight volumetric body, for example a non-gastight frigorific box. Hence, the entire refrigerant circuit of a heat pump unit may be surrounded by a sheet metal box, called the non-gastight frigorific box as it contains sufficient and large enough openings, for example a first opening and a second opening, to not be sealed, i.e. to not be gastight. As outlined below in detail, it is important that the design of the non-gastight frigorific box is not gastight.

[0062] The non-gastight volumetric body or, in particular, the non-gastight frigorific box enables to address at least some of the drawbacks nowadays available in commonly known solutions for reducing risks of flammable refrigerants that may leak from a refrigerant circuit of a heat pump unit.

[0063] According to several examples of the present disclosure and with reference to Figures 1 to 3, some features of the non-gastight frigorific box are described.

[0064] Namely, the volumetric body 110, in particular the non-gastight frigorific box 110 is installed as an operation position in a heat pump unit 100, in particular inside an outer casing or housing of the heat pump unit 100. The non-gastight frigorific box 110 comprises a bottom wall 111, a top wall 112, and a side wall 113. The side wall 113 comprises the four side faces or side panels that form the box shape, i.e. the front face or front panel 113-3, the back face or back panel 113-1, the right-side face or the right-side panel 113-4, and the left-side face or the left-side panel 113-2. The housing of the heat pump unit 100 comprises a housing bottom wall 101, a housing top wall 102 and a housing side wall 103. Similar, the housing side wall 103 comprises the four side faces or side panels that form the box shape of the housing, for example the housing back face or housing back panel 103-1. The non-gastight frigorific box 110 may comprise a first release opening or opening 114 and a second release opening or opening 115. The housing 100 may comprise a first heat pump unit opening 104 and a second heat pump unit opening 105. The first opening 114 and the first heat pump unit opening 104 may be connected for gaseous communication, and the second opening 115 and the second heat pump unit opening 105 may be connected for gaseous communication, so that no gas may be emitted from the non-gastight frigorific box 110 into the interior of the housing 100 but only to the outside of the housing 100. It is schematically indicated that the non-gastight frigorific box 110 accommodates at least part of a refrigerant circuit 120 of the heat pump unit 100. Moreover, it may be distinguished between four different spaces. A first space Ins inside the non-gastight frigorific box 110, a second space Out1 outside the non-gastight frigorific box 110 and inside the housing 100, and a space Out2 or Out 3 outside the housing 100. If the heat pump unit 100 is installed in an indoor space 1000, a third space Out2 is outside the housing 100 and inside the indoor space 1000, and a fourth space Out3 is outside the indoor space 1000. The first opening 114 and the second opening 115 are configured for gaseous communication between the first space Ins and one of the second to fourth spaces Out1, Ou2 and Out 3. A first distance D1 from the first opening 114 to the bottom wall 111 is larger than a second distance D2 from the second opening 115 to the bottom wall 111. A third distance D3, which is the first distance D1 subtracted by the second distance D2, may be in a range between 1 cm to 75 cm. A fourth distance D4 is a smallest distance from the second opening 115 to the bottom wall 111, and wherein the fourth distance D4 is in a range between 0 cm, so that a portion of the edge of the second opening 115 forms at least part of the edge of the bottom wall 111, and 75 cm. In Figure 3, a distance between a middle section of the first opening 114 and a middle section of the second opening 115 is indicated to be 330 mm, for example.

[0065] In more detail and according to several examples of the present disclosure, at least some of the drawbacks are solved by the non-gastight frigorific box as disclosed herein, which accommodates at least a potential leaking point of a heat pump unit's refrigerant circuit. For example, such potential leaking point may be one of the compressor, the utilization-side heat exchanger (e.g. for space heating, space cooling, domestic hot water and the like), the heat-source-side heat exchanger (e.g. ground source / water source / outdoor air source heat exchanger), the expansion device, the filter drier, brazing surfaces, the sight glass, a four-way valve, an oil separator, temperature and / or pressure gauges, the liquid receiver and suction accumulator and the refrigerant piping. Therefore, in the event of a leak in the heat pump unit's refrigerant circuit, a flow of leaking flammable refrigerant, for example R290, can be safely exhausted to the exterior of the outer casing of the heat pump unit, via at least one release opening in the non-gastight frigorific box, preferably via two such release openings, preferably at a sufficiently high position. The sufficiently high position of the at least one release opening in the non-gastight frigorific box may be a position on a top wall (also referred to as top panel or top face) of the non-gastight frigorific box and / or a position on one or more side walls (also referred to as side panels or side faces) of the non-gastight frigorific box. The at least one release opening may also be positioned in a bottom wall (also referred to as a bottom panel or bottom face) of the non-gastight frigorific box. In general, one or more release openings of the at least one release opening may be positioned or arranged in different or same walls, i.e. in the bottom wall, the top wall or in one of the side wall(s). Due to the at least one release opening in the non-gastight frigorific box, the non-gastight frigorific box thereby reliably dilutes the flammable refrigerant inside an indoor installation space. The indoor installation space is an indoor space where the heat pump unit is installed that accommodates the non-gastight frigorific box. For example, the indoor space is a space or a room inside a building, for example, a domestic house, having a surface area of equal to or less than 200 m 2< . Moreover, the non-gastight frigorific box thereby further impedes the flow within the interior of the outer casing or housing of the heat pump unit (that accommodates the non-gastight frigorific box) towards potential ignition sources inside the heat pump unit's outer casing or housing. For example, one or more exhaust holes are positioned at a side wall of the frigorific box that is parallel and / or close to a side wall of the heat pump unit's outer casing or housing. Thus, leaked R290 for example can directly flow from the non-gastight frigorific box to the indoor installation space rather than inside the heat pump unit's outer casing or housing.

[0066] According to several examples of the present disclosure, a leaking refrigerant may primarily accumulate inside the non-gastight frigorific box which, in a first step, avoids a direct emission of said leaking refrigerant to the indoor installation space. If the flammable refrigerant continues to leak and stream into the non-gastight frigorific box, leaking refrigerant can be exhausted from the release opening to the indoor installation space at a sufficiently high position. This supports the dilution of the flammable refrigerant inside the indoor installation space and reduces the risk of a concentration of flammable refrigerant that could lead to inflammation and fire. Such a configuration is especially advantageous in small indoor spaces, for example in domestic application both new build and renovation.

[0067] It shall be noted that a further technical problem arises, if the heat pump unit's refrigerant circuit contains more than 152 grams of the flammable refrigerant R290. In particular, for more than 152 grams of the flammable refrigerant R290, this leaked R290 must be exhausted outdoors, as imposed by IEC 60335-2-40:2022 EXV, as too high refrigerant concentrations could lead to a dangerous situation.

[0068] In view thereof, according to several examples of the present disclosure, the non-gastight volumetric body or, in particular, the non-gastight frigorific box comprises two release openings in the non-gastight frigorific box and a means of mechanical ventilation such that sufficient ventilation is created through the non-gastight frigorific box. That is, at least one fan is positioned in one of the exhaust holes to exhaust the leaked refrigerant accumulated inside the non-gastight frigorific box to the outside through an exhaust ventilation duct. This fan may run continuously, other than for short periods for maintenance and service. Alternatively, this fan may be triggered to run once a predetermined upper limit amount or concentration of a flammable refrigerant is detected by a detecting means, for example a sensor, inside the non-gastight frigorific box. It shall be noted that in case there would only be one exhaust hole, the non-gastight frigorific box design would not comply with the Q min air flow rate requirement (for the more than 152 grams R290 situation). The air flow rate would be too low because of a too tight frigorific box; which was found out by the inventors during tests in simulation. So, for a heat pump unit model containing the more than 152 grams of flammable refrigerant R290, there is needed the second release opening to reach Q min . The second exhaust hole increases the air flow rate such that the design complies with the air flow rate imposed by the standard. By such solution, application of a large enough fan to achieve a sufficient air flow rate is avoided. Therefore, also a larger electricity consumption of the fan is avoided that would negatively impact the (Seasonal) Coefficient of Performance ((S)COP) and the (Seasonal) Energy Efficiency Ratio ((S)EER).

[0069] Hence, according to several examples of the present disclosure, it may be said that the frigorific box is non-gastight, which is achieved by making release openings in the frigorific box. However, making release openings at random locations of the frigorific box may make it more difficult to solve the above-outlined technical problems. Therefore, the frigorific box according to several examples of the present disclosure features two release openings, preferably in a same side wall or in different side walls (thus, preferably not in the top wall, preferably not in the bottom wall), such that air circulation through the frigorific box results in the minimum exhaust air flow rate Q min as required by the standard IEC 60335-2-40:2022 EXV Annex GG.4 thereby solving the above-outlined technical problems, also for heat pump units containing more than the 152 grams of the flammable refrigerant R290. Optionally, a fan may be arranged at one of the two release openings to improve air circulation, in particular to achieve at least the minimum exhaust air flow rate Q min .

[0070] According to several examples of the present disclosure, having the two release openings in a same wall of the non-gastight frigorific box is a preferred solution. Namely, for example, having the two release openings in opposite walls of the frigorific box, for example in a front wall and in a back wall, a leaked flammable refrigerant will flow towards the interior of the heat pump unit's outer casing or housing where possible ignition sources are located.

[0071] Moreover, according to several examples of the present disclosure, the non-gastight frigorific box has a tight sealing gasket to prevent leaked R290 entering from outside the outer heat pump unit's casing or housing again into the non-gastight frigorific box. As the non-gastight frigorific box can slide over supports, for example, when replacing the entire frigorific box or during its production, maintaining the gasket position is made easier by arranging the two release openings in a same wall. Alternatively one of the two release openings may be arranged in the top wall. The gasket should not be removed or change position while sliding the non-gastight frigorific box over the supports. With the non-gastight frigorific box according to several examples of the present disclosure, the gasket, which may be positioned at the back of the frigorific box where the two release openings may be arranged, does not interfere with the sliding mechanism. Alternatively, if the non-gastight frigorific box does not slide over supports, the gasket may be positioned at the bottom of the frigorific box where at least one release opening may be arranged.

[0072] According to several examples of the present disclosure and with reference to Figures 4 to 10, the non-gastight frigorific box is described in more detail. It shall be noted that the non-gastight frigorific box 110 according to Figures 1 to 3 may represent the non-gastight frigorific box 1 according to Figures 4 to 10.

[0073] Namely, the non-gastight frigorific box 1 may house a refrigerant circuit of a heat pump unit. The refrigerant circuit may accommodate at least one of: a compressor 2, a utilisation-side heat exchanger 3, a heat-source-side heat exchanger 4 and an expansion device 5. Moreover, the non-gastight frigorific box 1 may comprise one or more smaller openings 6 adapted to fluidically connect both the utilisation-side heat exchanger 3 and the heat-source side heat exchanger 4, which are inside the frigorific box 1, with the rest of the heating circuit of the heat pump unit, which is located outside the frigorific box 1. Further, one or more smaller openings 7 may be adapted to electrically connect electronic devices present in the frigorific box 1 with the electronic circuit board, which is located outside the frigorific box 1. Both separated power supply and data communication cables can run through these smaller openings 7. Further, one or more smaller openings may be adapted to drain condensate accumulated in the frigorific box 1. The drainage opening may comprise a controllable valve that allows to drain any water from the frigorific box but avoids gaseous communication between the inside and outside of the frigorific box. Additionally, one or more smaller openings 8 may be adapted to connect an air pressure switch. The function of the air pressure switch is to monitor the air pressure inside the frigorific box 1 and to trigger an alarm or shutdown. This safety system is configured to obtain an indication of the pressure difference between the interior of the frigorific box and the ambient air outside of the frigorific box by measuring the pressure in the inner space of the frigorific box. This provides an indication of the pressure difference as the ambient pressure outside the enclosure is relatively constant, although depending on the altitude. For instance, at sea level the ambient pressure is typically 1013 hPa.

[0074] The air pressure switch can interrupt by opening its contacts the control circuit of an electrical component such as the compressor based on a preset threshold for the minimum depression of the air inside the frigorific box 1 relative to the ambient air outside of the frigorific box. The preset threshold could be determined based on the altitude of the installation site. The preset threshold could be set at a value of 20 Pa to 100 Pa, in particular 30 Pa, below the defined or measured ambient pressure at the altitude. The ambient pressure can be measured and updated upon installation. For instance, at sea level the pressure inside the enclosure can be selected from the range 913 hPa - 993 hPa. Hence, the goal may be to keep the R290 inside the frigorific box 1 and to prevent leaked R290 from further spreading inside the heat pump unit such that the R290 can be safely evacuated outside the heat pump unit through the two release openings 9 inside the frigorific box 1. In more detail, the two release openings 9 are adapted to exhaust leaking refrigerant to the exterior of the outer heat pump unit's casing or housing. In Figure 8, the four arrows denote different layers: from top to bottom, the first arrow indicates the heat pump unit's sheet metal outer casing, the second arrow indicates an acoustic insulation foam between the heat pump unit's outer casing and the non-gastight frigorific box 1 (this acoustic foam has no function as a tightness gasket to prevent leaked R290 from migrating into the non-gastight frigorific box 1 again), the third arrow indicates a back sheet metal plate of the non-gastight frigorific box 1, and the fourth arrow indicates an expanded polypropylene (EPP) insulation inside the non-gastight frigorific box 1 which houses the evaporator and condenser plate heat exchanger. Not shown in Figure 8 is that a gasket is placed in a groove in the EPP housing. The plastic support presses against this gasket. Therefore, the gasket is kept in place by both the EPP housing and the plastic support. With reference to Figures 9 and 10, a plastic or metal grid cover 10 covering the release opening 9 may be provided to hamper the entrance of rodents and large debris, however not obstructing the exhaust of refrigerant. The actual release opening size may be defined by the small opening in the noise baffle, as depicted. The plastic or metal grid cover 10 may be mounted in various ways. The plastic or metal grid cover 10 openings may be positioned above, below, left to and / or right to the center of the plastic grid cover. Either two sheet metal noise baffles with grid cover 10 or one sheet metal noise baffle with gid cover and an extraction fan 11 are placed in the release openings 9. Exhaust can be mainly realised by means of an extraction fan, for example for heat pump units containing more than the 152 grams of the flammable refrigerant R290 (Figure 10) or by means of natural convection through the noise baffle with plastic grid (Figure 9).

[0075] According to several examples of the present disclosure and with reference to Figures 11 to 13, different ventilation ducting design concepts are described in more detail. Based on Figure 1, each of Figures 11 to 13 schematically illustrate the volumetric body 110, in particular the non-gastight frigorific box 110 that is installed as an operation position in a heat pump unit 100, in particular inside an outer casing or housing of the heat pump unit 100. For each of Figures 11 to 13, a first space inside the non-gastight frigorific box 110, a second space outside the non-gastight frigorific box 110 and inside the housing 100, a space Out2 outside the housing 100 and inside the indoor space 1000, and (optionally) a space Out 3 outside the housing 100 are shown. Moreover, in each of Figures 11 to 13, air enters from the space Out2 through the first heat pump unit opening of the heat pump unit's casing and through the first opening of the non-gastight frigorific box 110 into the first space inside the non-gastight frigorific box 110. The air may enter through a grid cover 10 as schematically illustrated in each of Figures 11 to 13. Furthermore, in each of Figures 11 to 13, air may exit from the first space inside the non-gastight frigorific box 110 through the second opening of the non-gastight frigorific box 110 and through the second heat pump unit opening of the heat pump unit's casing into a ventilation duct 130.

[0076] In view thereof, referring now to Figure 11, Figure 11 illustrates a first ventilation ducting design concept according to several examples of the present disclosure. In more detail, air that is present in the indoor installation space Out2 enters the non-gastight frigorific box 110. The air is then exhausted to outdoors via single wall ventilation pipe 130 that may have an outer diameter of about 125 mm, for example. The ventilation pipe 130 may be made of plastic or metal (like PVC, EPS, aluminium or steel for example). The ducting of the ventilation pipe 130 to the second heat pump unit opening of the heat pump unit's casing (and to the second opening of the non-gastight frigorific box 110) can be rigid or flexible. The ducting may comprise a plurality of sections that are in gaseous communication with each other. Further, at least one section of the ducting may be flexible. The ducting may be thermally insulated to prevent condensation. The ducting may be acoustically insulated to attenuate airborne noise. The shape of the ducting is circular. The ducting is preferably gas-tight to avoid leaked flammable refrigerant to diffuse through the ventilation ducting material. The inlet / outlet of the ventilation ducting may be protected against rain, slanting wind, and pollution via e.g., a terminal.

[0077] This concept may have the following advantages, in that it is enabled to realize a minimal entry of cold air, i.e. of air from the space Out3 for example. Therefore, the indoor installation space temperature and energy efficiency may only be minimally affected.

[0078] This concept may have the following disadvantages, in that a single wall duct provides less acoustic performance. Further, since air out of the room, i.e. the space Out2, is used, there is the possibility of an under-pressure room (or building). Also, a larger fan is needed, which results in an inferior acoustic performance and a larger energy consumption.

[0079] Referring now to Figure 12, Figure 12 illustrates a second ventilation ducting design concept according to several examples of the present disclosure. In more detail, air that is present in the indoor installation space Out2 enters the non-gastight frigorific box 110. This air in space Out2 is provided from outdoors, i.e. the space Out3, using an outer sheath of a concentric pipe that is provided around the ventilation pipe 130, wherein the provided air mixes with air present in the indoor installation space Out2 prior to entering the non-gastight frigorific box 110. The concentric pipe may have an inner diameter of about 80 mm and an outer diameter of about 125 mm for example. The ventilation pipe 130 may be made of plastic or metal (like PVC, EPS, aluminium or steel for example). The ducting of the ventilation pipe 130 to the second heat pump unit opening of the heat pump unit's casing (and to the second opening of the non-gastight frigorific box 110) can be rigid or flexible. The ducting may comprise a plurality of sections that are in gaseous communication with each other. Further, at least one section of the ducting may be flexible. The ducting may be thermally insulated to prevent condensation. The ducting may be acoustically insulated to attenuate airborne noise. The shape of the ducting is circular. The ducting is preferably gas-tight to avoid leaked flammable refrigerant to diffuse through the ventilation ducting material. The inlet / outlet of the ventilation ducting may be protected against rain, slanting wind, and pollution via e.g., a terminal.

[0080] This concept may have the following advantages, in that it is enabled to use air from outside, i.e. from the space Out3, which has a limited effect on room / building pressure, so a pressure in a room / building stays in an acceptable range. There is provided (in comparison to the solution as shown according to Figure 11) a better acoustic performance due the concentric pipe. Further, a smaller fan is possible.

[0081] This concept may have the following disadvantages, in that there may be a blocking of air supply inside the room, there may be a blocking of air supply outside, and there may be an influence on building energy efficiency, since cold air may be emitted from Out3 into Out2 (i.e. into the room) for example.

[0082] Referring now to Figure 13, Figure 13 illustrates a third ventilation ducting design concept according to several examples of the present disclosure. In more detail, air that is present in the indoor installation space Out2 enters the non-gastight frigorific box 110 and air directly drawn from outdoors, i.e. the space Out3, using an outer sheath of a concentric pipe that is provided around the ventilation pipe 130, enters the non-gastight frigorific box 110. The concentric pipe may have an inner diameter of about 80 mm and an outer diameter of about 125 mm for example. The ventilation pipe 130 may be made of plastic or metal (like PVC, EPS, aluminium or steel for example). The ducting of the ventilation pipe 130 to the second heat pump unit opening of the heat pump unit's casing (and to the second opening of the non-gastight frigorific box 110) can be rigid or flexible. The ducting may comprise a plurality of sections that are in gaseous communication with each other. Further, at least one section of the ducting may be flexible. The ducting may be thermally insulated to prevent condensation. The ducting may be acoustically insulated to attenuate airborne noise. The shape of the ducting is circular. The ducting is preferably gas-tight to avoid leaked flammable refrigerant to diffuse through the ventilation ducting material. The inlet / outlet of the ventilation ducting may be protected against rain, slanting wind, and pollution via e.g., a terminal.

[0083] This concept may have the following advantages, in that it is enabled to use air from outside, i.e. from the space Out3. There is provided (in comparison to the solution as shown according to Figure 11) a better acoustic performance due the concentric pipe. Further, a temperature in the room / building is not affected.

[0084] This concept may have the following disadvantages, for example of a possible under-pressure room / building, since air from the room, i.e. the space Out2 is used. Further, a blocking of air supply outside is possible.

[0085] According to several examples of the present disclosure, the solution as illustrated according to Figure 12 may be preferred from a technical point of view, because of comparatively highest operational reliability, a high energy efficiency of the fan, an ease of installation, a comparatively little possibility to make mistakes during the installation, and a low cost price. However, a drawback of the solution as illustrated according to Figure 12 compared to the solutions illustrated according to Figures 11 and 13 is the possible comfort issue, since the temperature of the room / building may be affected as hot or cold air from the outdoors (i.e. space Out3) enters the indoor installation space (i.e. space Out2) during summer or winter.

[0086] Further, the design of an adapter unit 12 as illustrated in each of Figures 11 to 13 is different in Figure 11, Figure 12, and Figure 13 as a required function of the adapter unit 12 is slightly different for the three ventilation ducting concepts. Namely, a function of the adapter unit 12 in Figure 11 comprises to position the extraction fan and to fixate the ventilation duct. The function of the adapter unit 12 in Figure 12 comprises to position the extraction fan and to fixate the ventilation duct and to guide air from the outdoors to the indoor installation space. The function of the adapter unit 12 in Figure 13 comprises to position the extraction fan and to fixate the ventilation duct and to guide air from the outdoors directly to the inside of the non-gastight frigorific box 110.

[0087] Furthermore, regarding the concentric pipe, concentric pipe configurations may be interpreted as creating multiple functional openings within one physical opening or aperture.

[0088] According to several examples of the present disclosure, one or more of the following additional features may be considered. Namely, the non-gastight frigorific box can also be provided with sensors to detect a possible leakage of the refrigerant. Further, the non-gastight frigorific box can also be provided with acoustic insulation mounted to the sheet metal panels of the non-gastight frigorific box. The top, left, right, front, and back walls of the non-gastight frigorific box may all contain acoustic insulation foam on a surface facing inside the non-gastight frigorific box. There may be no acoustic insulation foam inside the non-gastight frigorific box attached to the bottom wall.

[0089] According to several examples of the present disclosure, having two exhaust holes instead of one helps in achieving the required minimum exhaust air flow rate stated in standard IEC 60335-2-40:2022 EXV, formulas GG.16 and GG.17 of Annex GG.4. The advantage of this solution is that a smaller fan with less electrical consumption can be chosen which positively affects the (S)COP and (S)EER of the heat pump unit.

[0090] According to several examples of the present disclosure, the non-gastight frigorific box may be made of sheet metal walls (also referred to as sheet metal plates) which are riveted together. The exhaust holes in the sheet metal wall may be laser cut or punched. The non-gastight frigorific box may be manufactured as a subassembly, tested, and then assembled into the final heat pump unit assembly. The sheet metal plates may be made by bending, deep drawing or stamping for example. Wherein corners may be welded to ensure leaked refrigerant does not escape through said corners.

[0091] According to several examples of the present disclosure, a gasket is placed in a groove in the EPP housing. The plastic support presses against this gasket. The gasket is kept in place by both the EPP housing and the plastic support. The plastic support is screwed onto the outer sheet metal casing and the EPP is attached to the non-gastight frigorific box sheet metal casing. The non-gastight frigorific box is fixed to supports of the heat pump unit's casing or housing. Hence, the design of the non-gastight frigorific box, in particular by placing the two release openings on, preferably, the back wall, is very reliable in terms of maintaining the gasket in place during production and maintenance of the non-gastight frigorific box.

Examples

Embodiment Construction

[0061]According to several examples of the present disclosure, there is described a design of a non-gastight volumetric body, for example a non-gastight frigorific box. Hence, the entire refrigerant circuit of a heat pump unit may be surrounded by a sheet metal box, called the non-gastight frigorific box as it contains sufficient and large enough openings, for example a first opening and a second opening, to not be sealed, i.e. to not be gastight. As outlined below in detail, it is important that the design of the non-gastight frigorific box is not gastight.

[0062]The non-gastight volumetric body or, in particular, the non-gastight frigorific box enables to address at least some of the drawbacks nowadays available in commonly known solutions for reducing risks of flammable refrigerants that may leak from a refrigerant circuit of a heat pump unit.

[0063]According to several examples of the present disclosure and with reference to Figures 1 to 3, some features of the non-gastight frigor...

Field of the Invention

[0001] The invention relates to a volumetric body for a heat pump unit operable with a refrigerant, to a heat pump unit comprising the volumetric body, to a use of the volumetric body and to a use of the heat pump unit.Background

[0002] In the event of a leak in a refrigerant circuit of a heat pump unit configured to be installed indoors, flammable refrigerant like R290 for example can flow to the indoor installation space or within the interior of the outer casing of the heat pump unit. In more detail, the leaking flammable refrigerant can flow to the indoor installation space in an uncontrolled manner and be exhausted to the indoor installation space at an insufficient height, resulting in a risk of a concentration of flammable refrigerant potentially causing inflammation. Alternatively or additionally, the leaking flammable refrigerant can flow within the interior of the outer casing of the heat pump unit and get into contact with potential ignition sources present in the heat pump unit, such as a Printed Circuit Board (PCB), the compressor inverter driver, and other electronic components which generate heat, resulting in a risk of fire in case the refrigerant concentration level reaches between the Lower Flammability Limit (LFL) and Upper Flammability Limit (UFL) at the location of the potential ignition source.

[0003] Nowadays, a solution that is often used to reduce the risks of leaking refrigerants, in particular of leaking flammable refrigerants, is the application of a sealed or gastight frigorific box. The sealed or gastight frigorific box houses at least part of the heat pump unit's refrigerant circuit, in particular at least such part where a leakage may be most likely. Due to the frigorific box being sealed or gastight, it is avoided that a leaking refrigerant flows out of the frigorific box in an uncontrolled manner.

[0004] In the event of a leak in a refrigerant circuit of a heat pump unit configured to be installed indoors and in case the heat pump refrigerant circuit contains more than 152 grams of R290, this leaked R290 must be exhausted outdoors as too high refrigerant concentrations could lead to a dangerous situation. To this extent, the heat pump unit must feature mechanical ventilation such that a minimum exhaust air flow rate Q min be reached at an under pressure of 20 Pa or more of the interior of the frigorific box relative to the indoor installation room. The minimum air flow rate, Q min , is computed using formulas GG.16 and GG.17 of Annex GG.4 of standard IEC 60335-2-40:2022 EXV. It shall be noted that if the heat pump unit comprising the more than 152 grams of R290 would be installed outdoors, leaking flammable refrigerant would diffuse in outdoor air resulting in a lower probability that the refrigerant concentration level would reach between the LFL and UFL at the location of the potential ignition source, and would result in a risk of fire. So, instead of using an exhaust fan, an alternative solution would be to only allow installation of a heat pump unit comprising the more than 152 grams of R290 outdoors.

[0005] To reduce the potential formation of a flammable concentration region, especially in small indoor spaces, the leaking flammable refrigerant is diluted. Such dilution process can be achieved by defining a required minimum exhaust height, which may depend on the available floorspace of the indoor space and the amount of flammable refrigerant used in the refrigerant circuit of the heat pump. Further, the leaking refrigerant usually is exhausted by means of a single exhaust opening.

[0006] However, the application of such single exhaust opening may lead to problems, for example if the exhaust path is clogged due to pollution, dust, or the like. Further, the application of a minimum exhaust height might face difficulties for proper dilution as the leaking refrigerant may not be efficiently drawn upward and expelled considering flammable refrigerants are denser than air.

[0007] Hence, there is room and need for improvement regarding the reduction of risks of flammable refrigerants leaking from a heat pump unit's refrigerant circuit.Summary

[0008] In view of the above, it is an object of the present disclosure to overcome at least part of the drawbacks available regarding the reduction of risks of flammable refrigerants leaking from a heat pump unit's refrigerant circuit. It shall be noted that throughout the present disclosure, a heat pump or heat pump unit may be a ground source heat pump using the ground as heat source or a water source heat pump using water as heat source or an air source heat pump using the air as heat source for example.

[0009] Therefore, to address one or more of these drawbacks, there is provided, in a first aspect, a volumetric body for a heat pump unit operable with a flammable refrigerant, wherein the volumetric body houses at least part of a refrigerant circuit of the heat pump unit. When the volumetric body is installed in an operation position, the volumetric body is defined by a bottom wall, a top wall and a side wall of the volumetric body and is a gas-tight volumetric body except for a first opening and a second opening. The first opening is provided in one of the bottom wall, the top wall and the side wall. The second opening is provided in one of the bottom wall, the top wall and the side wall. The first opening and the second opening are configured for gaseous communication between an inside and an outside of the volumetric body. A first distance from the first opening to the bottom wall is equal to or larger than a second distance from the second opening to the bottom wall. For reasons of understandability, it shall be noted that the volumetric body may be understood as the frigorific box (of the heat pump unit), i.e. the volumetric body is not the heat pump unit itself. Moreover, the first opening and the second opening are configured for discharging flammable refrigerant to an outside of the volumetric body in case of a flammable refrigerant leak inside the volumetric body. Hence, it may be said that one or both of the openings may discharge the flammable refrigerant to an outside of the volumetric body in case of the flammable refrigerant leaking inside the volumetric body.

[0010] The term "gas-tight" may also be understood as meaning "sealed". Moreover, for reasons of understandability, the term "gas-tight" or "sealed" in accordance with the present disclosure is not necessarily to be understood as excluding any openings, as outlined below in more detail. Hence, a cumulation of all openings in the gas-tight volumetric body, other than the first and second openings, may be smaller than 5 cm 2< . In this context, the "openings" may be understood as openings communicating the interior of the gas-tight volumetric body with an exterior environment or exterior space of the gas-tight volumetric body. Further, a single dimension, such as the diameter, of such an opening considered in the cumulation is more than 0.1 mm. Accordingly, openings having a dimension, such as a diameter, smaller than 0.1 mm are not considered as openings where leaking refrigerant can escape".

[0011] The term flammable is used with reference to the ASHRAE standards for refrigerants and EN 378-2:2016, defining the following classes: 1, 2L, 2, or 3, ranging from no flame propagation to high flame propagation and high heat of combustion.

[0012] The term flammable is used to refer to refrigerants that are highly flammable, class 3, such as R290 (propane), R600 (butane) and R600a (isobutane). Class 3 refrigerants, when tested, exhibit flame propagation at 140°F (60°C) and 14.7 psi (101.3 kPa) and that either has a heat of combustion of 19,000 kJ / kg (8,174 BTU / Ib) or greater or an LFL of 0.10 kg / m 3< or lower.

[0013] The term flammable may also be used here to refer to refrigerants from class 2 (flammable), such as R-152a or class 2L (mildly flammable) such as R-32, R-1234yf, R-1234ze, R-454C, R-454B.

[0014] Moreover, the volumetric body may be of any shape, and it shall be noted that the volumetric body is not sealed because there are two release openings, i.e. the first opening and the second opening. Said in other words, gas may flow into the volumetric body and / or out of the volumetric body through at least one of the first opening and the second opening. For explanation purposes, it shall be noted that an arrangement of the first opening and of the second opening is not limited to these openings being identical in shape and / or being arranged directly one above the other. Said in other words, in a cartesian coordinate system comprising the x-axis, y-axis and z-axis, in case the bottom wall is seen as an x-y-plane and in case the top wall is seen as being spaced apart from the bottom wall along the z-axis, the first opening and the second opening, in case they have different z-coordinates, do not need to have the same x-y-coordinates. Said in other words, it may be said that the first opening is farther away from the bottom wall as the second opening for example. However, in general, the first and second openings can be located anywhere on the walls of the volumetric body, i.e. on the top wall, on the bottom wall or on one or more side walls. For example, one or both of the first and second openings may be located on the top wall, on the bottom wall or on one or more side walls.

[0015] The term "wall" as used herein may be understood as being elements to define a shape of the volumetric body and / or an inner volume of the volumetric body. A wall may also be understood as representing one or more panels.

[0016] Furthermore, the volumetric body may be understood to represent a non-gastight volumetric body that accommodates at least a potential leaking point of a heat pump unit's refrigerant circuit. Potential leaking points of a heat pump unit's refrigerant circuit may be, for example, the compressor, the utilization-side heat exchanger, the heat-source-side heat exchanger, the expansion device, the filter drier, brazing surfaces, the sight glass, a four-way valve, an oil separator, temperature and / or pressure gauges, the liquid receiver and suction accumulator, and the refrigerant piping.

[0017] The term "expansion device" is to be interpreted broadly throughout the present disclosure to include an expansion valve that may be of the electronic or thermostatic type and to also cover a capillary tube, or the like facilitating the expansion of compressed refrigerant within the refrigerant circuit.

[0018] The term "equal to" comprises that the first and second openings may both be arranged in the top wall or the bottom wall.

[0019] Moreover, regarding the first and second openings, it should be noted that the first and second openings are not to be understood as openings for e.g., condensate draining, 0-50V communication, main 230 V power supply, means for transportation for example lifting, etc. Rather, the first and second openings may be understood as being independent and to have a distinct aperture. The openings are to be understood based on their physical features (distinct apertures) rather than on their functional characteristics (distinct flow pathways within a single opening).

[0020] The volumetric body is advantageous in several ways. For example, in the event of a leakage in the refrigerant circuit, the volumetric body allows that a flow of potentially flammable refrigerant (e.g., R290) can be safely exhausted to an outside of the volumetric body through at least one of the first opening and the second opening. In more detail, the flow of potentially flammable refrigerant can be safely exhausted to an exterior of an outer casing of the heat pump unit, via at least one of the first opening and the second opening. The volumetric body hampers a flow of potentially flammable refrigerant (e.g., R290) over potential ignition sources, thereby reducing the risk of ignition of the potentially flammable refrigerant. Moreover, the first opening and the second opening allow to create a fluid circulation through the volumetric body. Fresh air may enter the volumetric body at least through the first opening (i.e. the top opening) for example and may leave through the second opening (i.e. the bottom opening). The fresh air could come from an interior of a building in which the heat pump unit is installed and / or from an outdoor environment (for example an environment outside the building) to which leaked refrigerant can be exhausted. In general, fresh air could enter and / or exit through both openings. Such flow through the volumetric body is enabled through natural convection and / or forced convection for example. The driving factor for natural convection flow may be a density difference induced by a temperature gradient. For example, the gas inside of the volumetric body may be warmer than the fresh air entering the volumetric body. Additionally or alternatively, the driving factor for natural convection flow may be a density difference induced by a concentration gradient. The driving factor for forced convection may be the use of a fan or a blower.

[0021] According to several examples of the present disclosure, the volumetric body may be of a cylindrical shape and the side wall may be the curved surface area of the cylinder.

[0022] According to several examples of the present disclosure, the volumetric body may be of a prism or prismatic shape, wherein the bottom wall may represent a bottom face, wherein the top wall may represent a top face, and wherein the side wall may comprise a plurality of side faces that are side faces of the prism or prismatic shape, and wherein the first opening and the second opening are arranged at a same face. Alternatively, for reasons of understandability, the first opening and the second opening may be arranged at different faces. Moreover, the prism shape may be a cuboid shape for example.

[0023] For example, the volumetric body may be of a box or cuboid shape that has a bottom face, a top face and four side faces that form the side wall. A side face of the side wall may be understood as a panel that forms at least part of the side wall.

[0024] The first and second opening in the volumetric body, along with the corresponding openings in the heat pump unit's casing (which accommodates the volumetric body), may be positioned such that each opening in the volumetric body aligns with an opening in the heat pump unit's casing. These openings may be arranged either on the same face or on two perpendicular faces. Due to this arrangement, a direct gaseous communication path between the inside of the volumetric body and the outside of the heat pump unit is realized which simultaneously facilitates the dilution of the leaked flammable refrigerant by means of air from the indoor and / or outdoor environment and the exhaust of leaked flammable refrigerant avoiding interaction with potential ignition sources. Further, in such case, an installation of the volumetric body in the heat pump unit is made easier.

[0025] According to several examples of the present disclosure, the volumetric body may be of a cuboid shape, wherein the bottom wall may represent a bottom face, wherein the top wall may represent a top face, and wherein the side wall may comprise a plurality of side faces that are side faces of the cuboid shape, and wherein the first opening and the second opening are arranged at different faces.

[0026] Due to the first opening and the second opening being arranged at different faces, an efficiency of the ventilation of the gas through the inside of the volumetric body may be improved. In particular, improved ventilation is achieved and there is a lower concentration of flammable refrigerant inside the heat pump unit. This is what Computational Fluid Dynamics simulation results show.

[0027] According to several examples of the present disclosure, the first distance may be a smallest distance from the first opening to the bottom wall, and the second distance may be a largest distance from the second opening to the bottom wall.

[0028] Said in other words, it may be said that the first opening is arranged higher than the second opening, and that the first opening and the second opening do not overlap at a same height.

[0029] Due to the first opening and the second opening being arranged at different heights, an efficiency of the ventilation of the gas through the inside of the volumetric body is improved.

[0030] According to several examples of the present disclosure, a third distance, which is the first distance subtracted by the second distance, may be in a range between 1 cm to 75 cm.

[0031] Due to such third distance between the first opening and the second opening, a ventilation through the volumetric body is ensured.

[0032] According to several examples of the present disclosure, a fourth distance is a smallest distance from the second opening to the bottom wall, and wherein the fourth distance may be in a range between 0 cm, so that a portion of the edge of the second opening may form at least part of the edge of the bottom wall (111), and 75 cm.

[0033] In case the fourth distance is zero so that a portion of the edge of the second opening forms part of the edge of the bottom wall, leaking gas may easily and quickly flow out of the volumetric body through the second opening.

[0034] In case the fourth distance is greater than zero, leaking gas may accumulate inside the volumetric body which, in a first step, may at least reduce a direct emission of the gas to an indoor installation space in which the heat pump unit is installed for example. A sensor (e.g. as part of a leak detection system) may detect the leaking gas and may trigger a fan for blowing the gas out of the volumetric body for example. Additionally or alternatively, a fan may be used to exhaust the leaking gas continuously, other than for short periods for maintenance and service.

[0035] According to several examples of the present disclosure, the first opening may have a minimum cross-sectional area of at least 500 mm 2< , the second opening may have a minimum cross-sectional area of at least 500 mm 2< .

[0036] It shall be noted that the first opening and the second opening may be of any shape. The first opening and the second opening may be of a same shape. The first opening and the second opening may be of different shapes.

[0037] Due to these minimum cross-sectional areas, a minimum flow rate is enabled that allows for reliably guiding leaking gas out of the volumetric body.

[0038] According to several examples of the present disclosure, the volumetric body may further comprise a fan for promoting gaseous flow out of and / or into the volumetric body through at least one of the first opening and the second opening. The fan may be of the explosion-proof type.

[0039] It shall be noted that the fan may be configured to run continuously for blowing gas out of the first opening, if the fan is arranged at the first opening, or for blowing gas out of the second opening, if the fan is arranged at the second opening. For example, the fan may run continuously. Alternatively, according to several examples of the present disclosure, the volumetric body may further comprise a sensor arranged inside the volumetric body. The sensor may be configured to detect leaking gas. Further, the sensor may be configured to trigger the fan for blowing detected gas out of the volumetric body.

[0040] Hence, even greater amounts of leaking gas may be blown out of the volumetric body more reliably.

[0041] According to several examples of the present disclosure, the volumetric body may have a pressure difference between an inside and an outside of the volumetric body equal to a pressure difference in the range of 20 Pa - 100 Pa, preferably 30 Pa.

[0042] According to several examples of the present disclosure, the volumetric body may be a frigorific box housing at least part of the refrigerant circuit of the heat pump unit.

[0043] Moreover, according to a second aspect, there is provided a heat pump unit operable with a flammable refrigerant. The heat pump unit comprises a housing, a refrigerant circuit, and volumetric body according to the first aspect that is installed inside the housing. The housing houses the refrigerant circuit and the volumetric body. The volumetric body houses at least part of the refrigerant circuit. When the heat pump unit is installed in an operation position, the housing of the heat pump unit comprises a housing bottom wall, a housing top wall and a housing side wall. The housing comprises a first heat pump unit opening and a second heat pump unit opening. The first heat pump unit opening is provided in one of the housing bottom wall, the housing top wall and the housing side wall. The second heat pump unit opening is provided in one of the housing bottom wall, the housing top wall and the housing side wall. The first heat pump unit opening and the second heat pump unit opening are configured for gaseous communication between an inside and an outside of the heat pump unit. The first heat pump unit opening is in gaseous communication with the first opening of the volumetric body, and the second heat pump unit opening is in gaseous communication with the second opening of the volumetric body.

[0044] The housing of the heat pump unit may be understood as an outer casing of the heat pump unit. The first heat pump unit opening and the second heat pump unit opening may be arranged at a different housing face.

[0045] The volumetric body is advantageous in several ways. For example, gas from inside the volumetric body may be efficiently guided toward outside of the housing, i.e. toward an indoor installation environment and / or toward the outdoors, i.e. the outdoors of the indoor installation environment. Thus, a spreading of the gas inside the housing is hampered.

[0046] According to several examples of the present disclosure, the first heat pump unit opening may be connected to the first opening of the volumetric body, so that gas flowing into and / or out of the volumetric body through the first opening enters and / or exits the housing via the first heat pump unit opening. The second heat pump unit opening may be connected to the second opening of the volumetric body, so that gas flowing out of and / or into the volumetric body through the second opening exits and / or enters the housing via the second heat pump unit opening.

[0047] Hence, gas from inside the volumetric body may be guided even more efficiently toward outside of the housing, i.e. toward an indoor installation environment and / or toward the outdoors, i.e. the outdoors of the indoor installation environment. Thus, a spreading of the gas inside the housing is even further hampered.

[0048] According to several examples of the present disclosure, the housing bottom wall may represent a housing bottom face, the housing top wall may represent a housing top face, and the housing side wall may comprise a plurality of housing side faces. The first heat pump unit opening and the second heat pump unit opening may be arranged at a same housing face. The first heat pump unit opening and the second heat pump unit opening may be arranged to match or overlap the first opening and the second opening respectively.

[0049] According to several examples of the present disclosure, a distance between the side wall of the volumetric body and the housing side wall is at least 5 mm. An acoustic insulation element may be placed between the side wall of the volumetric body and the housing side wall.

[0050] Hence, it is avoided that the side wall of the volumetric body, when vibrating for example, is in contact with the housing side wall. Thus, it may be avoided that vibrations caused by the compressor inside the volumetric body affect the housing (i.e. the housing side wall). Therefore, such acoustic decoupling contributes to attenuate noise emission.

[0051] According to several examples of the present disclosure, the heat pump unit may further comprise a ventilation duct connected to the second heat pump unit opening for gas to flow out of the volumetric body into the ventilation duct through the second heat pump unit opening. Wherein one of the following three alternatives a), b) or c) may be provided: a) The ventilation duct is a regular pipe, a fan is provided in the second heat pump unit opening, and gas flows from a space outside of the heat pump unit and inside an installation space of the heat pump unit into the volumetric body through the first heat pump unit opening. b) The ventilation duct is surrounded by a concentric pipe that is not connected to the second heat pump unit opening but opens to a space outside of the heat pump unit and inside an installation space of the heat pump unit, a fan is provided in the second heat pump unit opening, gas flows from a space outside the installation space of the heat pump unit through the concentric pipe into the space outside of the heat pump unit and inside the installation space of the heat pump unit, and gas flows from the space outside of the heat pump unit and inside the installation space of the heat pump unit into the volumetric body through the first heat pump unit opening. c) The ventilation duct is surrounded by a concentric pipe that is connected to the second heat pump unit opening, a fan is provided in the second heat pump unit opening, gas flows from a space outside the installation space of the heat pump unit through the concentric pipe into the volumetric body through the second heat pump unit opening, and gas flows from the space outside of the heat pump unit and inside the installation space of the heat pump unit into the volumetric body through the first heat pump unit opening.

[0052] Furthermore, according to a third aspect, there is provided a use of the volumetric body according to the first aspect.

[0053] Further, according to a fourth aspect, there is provided a use of the heat pump unit according to the second aspect.

[0054] Optional features of the first aspect and / or the second aspect may form part of any of the third and fourth aspects, mutatis mutandis.

[0055] The indefinite article "a" or "an" does not exclude a plurality. In addition, the articles "a" and "an" as used herein should generally be construed to mean "one or more" unless specified otherwise or clear from the context to be directed to a singular form.

[0056] Unless specified otherwise, or clear from the context, the phrases "one or more of A, B and C", "at least one of A, B, and C", and "A, B and / or C" as used herein are intended to mean all possible permutations of one or more of the listed items. That is, the phrase "A and / or B" means (A), (B), or (A and B), while the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0057] The term "comprising" does not exclude other elements or steps. Furthermore, the terms "comprising", "including", "having" and the like may be used interchangeably herein.

[0058] The invention may include one or more aspects, examples or features in isolation or combination whether specifically disclosed in that combination or in isolation. Any optional feature or sub-aspect of one of the above aspects applies as appropriate to any of the other aspects.

[0059] The above-described aspects will become apparent from, and elucidated with, reference to the detailed description provided hereinafter.Brief Description of the Drawings

[0060] A detailed description will now be given, by way of example only, with reference to the accompanying drawings, in which: Figure 1 schematically illustrates a volumetric body arranged inside an empty casing of a heat pump unit according to several examples of the present disclosure; Figure 2 illustrates in a three-dimensional view a volumetric body spaced apart from a casing of a heat pump unit according to several examples of the present disclosure; Figure 3 illustrates in a three-dimensional view the volumetric body of Figure 2 arranged inside the empty casing of the heat pump unit of Figure 2 according to several examples of the present disclosure; Figure 4 illustrates the volumetric body of Figure 2 arranged in the heat pump unit according to several examples of the present disclosure; Figure 5 illustrates an example for an arrangement of components of the heat pump unit's refrigerant circuit inside the volumetric body of Figure 4 according to several examples of the present disclosure; Figure 6 illustrates openings in the volumetric body of Figure 4 for control and / or operational purposes 4 according to several examples of the present disclosure; Figure 7 illustrates two release openings in the volumetric body of Figure 4 according to several examples of the present disclosure; Figure 8 illustrates one of the two release openings as shown in Figure 7 in more detail according to several examples of the present disclosure; Figures 9 and 10 illustrate different examples for arrangements in the two release openings as shown in Figure 7 according to several examples of the present disclosure; Figure 11 illustrates a first ventilation ducting design concept according to several examples of the present disclosure; Figure 12 illustrates a second ventilation ducting design concept according to several examples of the present disclosure; and Figure 13 illustrates a third ventilation ducting design concept according to several examples of the present disclosure. Detailed Description

[0061] According to several examples of the present disclosure, there is described a design of a non-gastight volumetric body, for example a non-gastight frigorific box. Hence, the entire refrigerant circuit of a heat pump unit may be surrounded by a sheet metal box, called the non-gastight frigorific box as it contains sufficient and large enough openings, for example a first opening and a second opening, to not be sealed, i.e. to not be gastight. As outlined below in detail, it is important that the design of the non-gastight frigorific box is not gastight.

[0062] The non-gastight volumetric body or, in particular, the non-gastight frigorific box enables to address at least some of the drawbacks nowadays available in commonly known solutions for reducing risks of flammable refrigerants that may leak from a refrigerant circuit of a heat pump unit.

[0063] According to several examples of the present disclosure and with reference to Figures 1 to 3, some features of the non-gastight frigorific box are described.

[0064] Namely, the volumetric body 110, in particular the non-gastight frigorific box 110 is installed as an operation position in a heat pump unit 100, in particular inside an outer casing or housing of the heat pump unit 100. The non-gastight frigorific box 110 comprises a bottom wall 111, a top wall 112, and a side wall 113. The side wall 113 comprises the four side faces or side panels that form the box shape, i.e. the front face or front panel 113-3, the back face or back panel 113-1, the right-side face or the right-side panel 113-4, and the left-side face or the left-side panel 113-2. The housing of the heat pump unit 100 comprises a housing bottom wall 101, a housing top wall 102 and a housing side wall 103. Similar, the housing side wall 103 comprises the four side faces or side panels that form the box shape of the housing, for example the housing back face or housing back panel 103-1. The non-gastight frigorific box 110 may comprise a first release opening or opening 114 and a second release opening or opening 115. The housing 100 may comprise a first heat pump unit opening 104 and a second heat pump unit opening 105. The first opening 114 and the first heat pump unit opening 104 may be connected for gaseous communication, and the second opening 115 and the second heat pump unit opening 105 may be connected for gaseous communication, so that no gas may be emitted from the non-gastight frigorific box 110 into the interior of the housing 100 but only to the outside of the housing 100. It is schematically indicated that the non-gastight frigorific box 110 accommodates at least part of a refrigerant circuit 120 of the heat pump unit 100. Moreover, it may be distinguished between four different spaces. A first space Ins inside the non-gastight frigorific box 110, a second space Out1 outside the non-gastight frigorific box 110 and inside the housing 100, and a space Out2 or Out 3 outside the housing 100. If the heat pump unit 100 is installed in an indoor space 1000, a third space Out2 is outside the housing 100 and inside the indoor space 1000, and a fourth space Out3 is outside the indoor space 1000. The first opening 114 and the second opening 115 are configured for gaseous communication between the first space Ins and one of the second to fourth spaces Out1, Ou2 and Out 3. A first distance D1 from the first opening 114 to the bottom wall 111 is larger than a second distance D2 from the second opening 115 to the bottom wall 111. A third distance D3, which is the first distance D1 subtracted by the second distance D2, may be in a range between 1 cm to 75 cm. A fourth distance D4 is a smallest distance from the second opening 115 to the bottom wall 111, and wherein the fourth distance D4 is in a range between 0 cm, so that a portion of the edge of the second opening 115 forms at least part of the edge of the bottom wall 111, and 75 cm. In Figure 3, a distance between a middle section of the first opening 114 and a middle section of the second opening 115 is indicated to be 330 mm, for example.

[0065] In more detail and according to several examples of the present disclosure, at least some of the drawbacks are solved by the non-gastight frigorific box as disclosed herein, which accommodates at least a potential leaking point of a heat pump unit's refrigerant circuit. For example, such potential leaking point may be one of the compressor, the utilization-side heat exchanger (e.g. for space heating, space cooling, domestic hot water and the like), the heat-source-side heat exchanger (e.g. ground source / water source / outdoor air source heat exchanger), the expansion device, the filter drier, brazing surfaces, the sight glass, a four-way valve, an oil separator, temperature and / or pressure gauges, the liquid receiver and suction accumulator and the refrigerant piping. Therefore, in the event of a leak in the heat pump unit's refrigerant circuit, a flow of leaking flammable refrigerant, for example R290, can be safely exhausted to the exterior of the outer casing of the heat pump unit, via at least one release opening in the non-gastight frigorific box, preferably via two such release openings, preferably at a sufficiently high position. The sufficiently high position of the at least one release opening in the non-gastight frigorific box may be a position on a top wall (also referred to as top panel or top face) of the non-gastight frigorific box and / or a position on one or more side walls (also referred to as side panels or side faces) of the non-gastight frigorific box. The at least one release opening may also be positioned in a bottom wall (also referred to as a bottom panel or bottom face) of the non-gastight frigorific box. In general, one or more release openings of the at least one release opening may be positioned or arranged in different or same walls, i.e. in the bottom wall, the top wall or in one of the side wall(s). Due to the at least one release opening in the non-gastight frigorific box, the non-gastight frigorific box thereby reliably dilutes the flammable refrigerant inside an indoor installation space. The indoor installation space is an indoor space where the heat pump unit is installed that accommodates the non-gastight frigorific box. For example, the indoor space is a space or a room inside a building, for example, a domestic house, having a surface area of equal to or less than 200 m 2< . Moreover, the non-gastight frigorific box thereby further impedes the flow within the interior of the outer casing or housing of the heat pump unit (that accommodates the non-gastight frigorific box) towards potential ignition sources inside the heat pump unit's outer casing or housing. For example, one or more exhaust holes are positioned at a side wall of the frigorific box that is parallel and / or close to a side wall of the heat pump unit's outer casing or housing. Thus, leaked R290 for example can directly flow from the non-gastight frigorific box to the indoor installation space rather than inside the heat pump unit's outer casing or housing.

[0066] According to several examples of the present disclosure, a leaking refrigerant may primarily accumulate inside the non-gastight frigorific box which, in a first step, avoids a direct emission of said leaking refrigerant to the indoor installation space. If the flammable refrigerant continues to leak and stream into the non-gastight frigorific box, leaking refrigerant can be exhausted from the release opening to the indoor installation space at a sufficiently high position. This supports the dilution of the flammable refrigerant inside the indoor installation space and reduces the risk of a concentration of flammable refrigerant that could lead to inflammation and fire. Such a configuration is especially advantageous in small indoor spaces, for example in domestic application both new build and renovation.

[0067] It shall be noted that a further technical problem arises, if the heat pump unit's refrigerant circuit contains more than 152 grams of the flammable refrigerant R290. In particular, for more than 152 grams of the flammable refrigerant R290, this leaked R290 must be exhausted outdoors, as imposed by IEC 60335-2-40:2022 EXV, as too high refrigerant concentrations could lead to a dangerous situation.

[0068] In view thereof, according to several examples of the present disclosure, the non-gastight volumetric body or, in particular, the non-gastight frigorific box comprises two release openings in the non-gastight frigorific box and a means of mechanical ventilation such that sufficient ventilation is created through the non-gastight frigorific box. That is, at least one fan is positioned in one of the exhaust holes to exhaust the leaked refrigerant accumulated inside the non-gastight frigorific box to the outside through an exhaust ventilation duct. This fan may run continuously, other than for short periods for maintenance and service. Alternatively, this fan may be triggered to run once a predetermined upper limit amount or concentration of a flammable refrigerant is detected by a detecting means, for example a sensor, inside the non-gastight frigorific box. It shall be noted that in case there would only be one exhaust hole, the non-gastight frigorific box design would not comply with the Q min air flow rate requirement (for the more than 152 grams R290 situation). The air flow rate would be too low because of a too tight frigorific box; which was found out by the inventors during tests in simulation. So, for a heat pump unit model containing the more than 152 grams of flammable refrigerant R290, there is needed the second release opening to reach Q min . The second exhaust hole increases the air flow rate such that the design complies with the air flow rate imposed by the standard. By such solution, application of a large enough fan to achieve a sufficient air flow rate is avoided. Therefore, also a larger electricity consumption of the fan is avoided that would negatively impact the (Seasonal) Coefficient of Performance ((S)COP) and the (Seasonal) Energy Efficiency Ratio ((S)EER).

[0069] Hence, according to several examples of the present disclosure, it may be said that the frigorific box is non-gastight, which is achieved by making release openings in the frigorific box. However, making release openings at random locations of the frigorific box may make it more difficult to solve the above-outlined technical problems. Therefore, the frigorific box according to several examples of the present disclosure features two release openings, preferably in a same side wall or in different side walls (thus, preferably not in the top wall, preferably not in the bottom wall), such that air circulation through the frigorific box results in the minimum exhaust air flow rate Q min as required by the standard IEC 60335-2-40:2022 EXV Annex GG.4 thereby solving the above-outlined technical problems, also for heat pump units containing more than the 152 grams of the flammable refrigerant R290. Optionally, a fan may be arranged at one of the two release openings to improve air circulation, in particular to achieve at least the minimum exhaust air flow rate Q min .

[0070] According to several examples of the present disclosure, having the two release openings in a same wall of the non-gastight frigorific box is a preferred solution. Namely, for example, having the two release openings in opposite walls of the frigorific box, for example in a front wall and in a back wall, a leaked flammable refrigerant will flow towards the interior of the heat pump unit's outer casing or housing where possible ignition sources are located.

[0071] Moreover, according to several examples of the present disclosure, the non-gastight frigorific box has a tight sealing gasket to prevent leaked R290 entering from outside the outer heat pump unit's casing or housing again into the non-gastight frigorific box. As the non-gastight frigorific box can slide over supports, for example, when replacing the entire frigorific box or during its production, maintaining the gasket position is made easier by arranging the two release openings in a same wall. Alternatively one of the two release openings may be arranged in the top wall. The gasket should not be removed or change position while sliding the non-gastight frigorific box over the supports. With the non-gastight frigorific box according to several examples of the present disclosure, the gasket, which may be positioned at the back of the frigorific box where the two release openings may be arranged, does not interfere with the sliding mechanism. Alternatively, if the non-gastight frigorific box does not slide over supports, the gasket may be positioned at the bottom of the frigorific box where at least one release opening may be arranged.

[0072] According to several examples of the present disclosure and with reference to Figures 4 to 10, the non-gastight frigorific box is described in more detail. It shall be noted that the non-gastight frigorific box 110 according to Figures 1 to 3 may represent the non-gastight frigorific box 1 according to Figures 4 to 10.

[0073] Namely, the non-gastight frigorific box 1 may house a refrigerant circuit of a heat pump unit. The refrigerant circuit may accommodate at least one of: a compressor 2, a utilisation-side heat exchanger 3, a heat-source-side heat exchanger 4 and an expansion device 5. Moreover, the non-gastight frigorific box 1 may comprise one or more smaller openings 6 adapted to fluidically connect both the utilisation-side heat exchanger 3 and the heat-source side heat exchanger 4, which are inside the frigorific box 1, with the rest of the heating circuit of the heat pump unit, which is located outside the frigorific box 1. Further, one or more smaller openings 7 may be adapted to electrically connect electronic devices present in the frigorific box 1 with the electronic circuit board, which is located outside the frigorific box 1. Both separated power supply and data communication cables can run through these smaller openings 7. Further, one or more smaller openings may be adapted to drain condensate accumulated in the frigorific box 1. The drainage opening may comprise a controllable valve that allows to drain any water from the frigorific box but avoids gaseous communication between the inside and outside of the frigorific box. Additionally, one or more smaller openings 8 may be adapted to connect an air pressure switch. The function of the air pressure switch is to monitor the air pressure inside the frigorific box 1 and to trigger an alarm or shutdown. This safety system is configured to obtain an indication of the pressure difference between the interior of the frigorific box and the ambient air outside of the frigorific box by measuring the pressure in the inner space of the frigorific box. This provides an indication of the pressure difference as the ambient pressure outside the enclosure is relatively constant, although depending on the altitude. For instance, at sea level the ambient pressure is typically 1013 hPa.

[0074] The air pressure switch can interrupt by opening its contacts the control circuit of an electrical component such as the compressor based on a preset threshold for the minimum depression of the air inside the frigorific box 1 relative to the ambient air outside of the frigorific box. The preset threshold could be determined based on the altitude of the installation site. The preset threshold could be set at a value of 20 Pa to 100 Pa, in particular 30 Pa, below the defined or measured ambient pressure at the altitude. The ambient pressure can be measured and updated upon installation. For instance, at sea level the pressure inside the enclosure can be selected from the range 913 hPa - 993 hPa. Hence, the goal may be to keep the R290 inside the frigorific box 1 and to prevent leaked R290 from further spreading inside the heat pump unit such that the R290 can be safely evacuated outside the heat pump unit through the two release openings 9 inside the frigorific box 1. In more detail, the two release openings 9 are adapted to exhaust leaking refrigerant to the exterior of the outer heat pump unit's casing or housing. In Figure 8, the four arrows denote different layers: from top to bottom, the first arrow indicates the heat pump unit's sheet metal outer casing, the second arrow indicates an acoustic insulation foam between the heat pump unit's outer casing and the non-gastight frigorific box 1 (this acoustic foam has no function as a tightness gasket to prevent leaked R290 from migrating into the non-gastight frigorific box 1 again), the third arrow indicates a back sheet metal plate of the non-gastight frigorific box 1, and the fourth arrow indicates an expanded polypropylene (EPP) insulation inside the non-gastight frigorific box 1 which houses the evaporator and condenser plate heat exchanger. Not shown in Figure 8 is that a gasket is placed in a groove in the EPP housing. The plastic support presses against this gasket. Therefore, the gasket is kept in place by both the EPP housing and the plastic support. With reference to Figures 9 and 10, a plastic or metal grid cover 10 covering the release opening 9 may be provided to hamper the entrance of rodents and large debris, however not obstructing the exhaust of refrigerant. The actual release opening size may be defined by the small opening in the noise baffle, as depicted. The plastic or metal grid cover 10 may be mounted in various ways. The plastic or metal grid cover 10 openings may be positioned above, below, left to and / or right to the center of the plastic grid cover. Either two sheet metal noise baffles with grid cover 10 or one sheet metal noise baffle with gid cover and an extraction fan 11 are placed in the release openings 9. Exhaust can be mainly realised by means of an extraction fan, for example for heat pump units containing more than the 152 grams of the flammable refrigerant R290 (Figure 10) or by means of natural convection through the noise baffle with plastic grid (Figure 9).

[0075] According to several examples of the present disclosure and with reference to Figures 11 to 13, different ventilation ducting design concepts are described in more detail. Based on Figure 1, each of Figures 11 to 13 schematically illustrate the volumetric body 110, in particular the non-gastight frigorific box 110 that is installed as an operation position in a heat pump unit 100, in particular inside an outer casing or housing of the heat pump unit 100. For each of Figures 11 to 13, a first space inside the non-gastight frigorific box 110, a second space outside the non-gastight frigorific box 110 and inside the housing 100, a space Out2 outside the housing 100 and inside the indoor space 1000, and (optionally) a space Out 3 outside the housing 100 are shown. Moreover, in each of Figures 11 to 13, air enters from the space Out2 through the first heat pump unit opening of the heat pump unit's casing and through the first opening of the non-gastight frigorific box 110 into the first space inside the non-gastight frigorific box 110. The air may enter through a grid cover 10 as schematically illustrated in each of Figures 11 to 13. Furthermore, in each of Figures 11 to 13, air may exit from the first space inside the non-gastight frigorific box 110 through the second opening of the non-gastight frigorific box 110 and through the second heat pump unit opening of the heat pump unit's casing into a ventilation duct 130.

[0076] In view thereof, referring now to Figure 11, Figure 11 illustrates a first ventilation ducting design concept according to several examples of the present disclosure. In more detail, air that is present in the indoor installation space Out2 enters the non-gastight frigorific box 110. The air is then exhausted to outdoors via single wall ventilation pipe 130 that may have an outer diameter of about 125 mm, for example. The ventilation pipe 130 may be made of plastic or metal (like PVC, EPS, aluminium or steel for example). The ducting of the ventilation pipe 130 to the second heat pump unit opening of the heat pump unit's casing (and to the second opening of the non-gastight frigorific box 110) can be rigid or flexible. The ducting may comprise a plurality of sections that are in gaseous communication with each other. Further, at least one section of the ducting may be flexible. The ducting may be thermally insulated to prevent condensation. The ducting may be acoustically insulated to attenuate airborne noise. The shape of the ducting is circular. The ducting is preferably gas-tight to avoid leaked flammable refrigerant to diffuse through the ventilation ducting material. The inlet / outlet of the ventilation ducting may be protected against rain, slanting wind, and pollution via e.g., a terminal.

[0077] This concept may have the following advantages, in that it is enabled to realize a minimal entry of cold air, i.e. of air from the space Out3 for example. Therefore, the indoor installation space temperature and energy efficiency may only be minimally affected.

[0078] This concept may have the following disadvantages, in that a single wall duct provides less acoustic performance. Further, since air out of the room, i.e. the space Out2, is used, there is the possibility of an under-pressure room (or building). Also, a larger fan is needed, which results in an inferior acoustic performance and a larger energy consumption.

[0079] Referring now to Figure 12, Figure 12 illustrates a second ventilation ducting design concept according to several examples of the present disclosure. In more detail, air that is present in the indoor installation space Out2 enters the non-gastight frigorific box 110. This air in space Out2 is provided from outdoors, i.e. the space Out3, using an outer sheath of a concentric pipe that is provided around the ventilation pipe 130, wherein the provided air mixes with air present in the indoor installation space Out2 prior to entering the non-gastight frigorific box 110. The concentric pipe may have an inner diameter of about 80 mm and an outer diameter of about 125 mm for example. The ventilation pipe 130 may be made of plastic or metal (like PVC, EPS, aluminium or steel for example). The ducting of the ventilation pipe 130 to the second heat pump unit opening of the heat pump unit's casing (and to the second opening of the non-gastight frigorific box 110) can be rigid or flexible. The ducting may comprise a plurality of sections that are in gaseous communication with each other. Further, at least one section of the ducting may be flexible. The ducting may be thermally insulated to prevent condensation. The ducting may be acoustically insulated to attenuate airborne noise. The shape of the ducting is circular. The ducting is preferably gas-tight to avoid leaked flammable refrigerant to diffuse through the ventilation ducting material. The inlet / outlet of the ventilation ducting may be protected against rain, slanting wind, and pollution via e.g., a terminal.

[0080] This concept may have the following advantages, in that it is enabled to use air from outside, i.e. from the space Out3, which has a limited effect on room / building pressure, so a pressure in a room / building stays in an acceptable range. There is provided (in comparison to the solution as shown according to Figure 11) a better acoustic performance due the concentric pipe. Further, a smaller fan is possible.

[0081] This concept may have the following disadvantages, in that there may be a blocking of air supply inside the room, there may be a blocking of air supply outside, and there may be an influence on building energy efficiency, since cold air may be emitted from Out3 into Out2 (i.e. into the room) for example.

[0082] Referring now to Figure 13, Figure 13 illustrates a third ventilation ducting design concept according to several examples of the present disclosure. In more detail, air that is present in the indoor installation space Out2 enters the non-gastight frigorific box 110 and air directly drawn from outdoors, i.e. the space Out3, using an outer sheath of a concentric pipe that is provided around the ventilation pipe 130, enters the non-gastight frigorific box 110. The concentric pipe may have an inner diameter of about 80 mm and an outer diameter of about 125 mm for example. The ventilation pipe 130 may be made of plastic or metal (like PVC, EPS, aluminium or steel for example). The ducting of the ventilation pipe 130 to the second heat pump unit opening of the heat pump unit's casing (and to the second opening of the non-gastight frigorific box 110) can be rigid or flexible. The ducting may comprise a plurality of sections that are in gaseous communication with each other. Further, at least one section of the ducting may be flexible. The ducting may be thermally insulated to prevent condensation. The ducting may be acoustically insulated to attenuate airborne noise. The shape of the ducting is circular. The ducting is preferably gas-tight to avoid leaked flammable refrigerant to diffuse through the ventilation ducting material. The inlet / outlet of the ventilation ducting may be protected against rain, slanting wind, and pollution via e.g., a terminal.

[0083] This concept may have the following advantages, in that it is enabled to use air from outside, i.e. from the space Out3. There is provided (in comparison to the solution as shown according to Figure 11) a better acoustic performance due the concentric pipe. Further, a temperature in the room / building is not affected.

[0084] This concept may have the following disadvantages, for example of a possible under-pressure room / building, since air from the room, i.e. the space Out2 is used. Further, a blocking of air supply outside is possible.

[0085] According to several examples of the present disclosure, the solution as illustrated according to Figure 12 may be preferred from a technical point of view, because of comparatively highest operational reliability, a high energy efficiency of the fan, an ease of installation, a comparatively little possibility to make mistakes during the installation, and a low cost price. However, a drawback of the solution as illustrated according to Figure 12 compared to the solutions illustrated according to Figures 11 and 13 is the possible comfort issue, since the temperature of the room / building may be affected as hot or cold air from the outdoors (i.e. space Out3) enters the indoor installation space (i.e. space Out2) during summer or winter.

[0086] Further, the design of an adapter unit 12 as illustrated in each of Figures 11 to 13 is different in Figure 11, Figure 12, and Figure 13 as a required function of the adapter unit 12 is slightly different for the three ventilation ducting concepts. Namely, a function of the adapter unit 12 in Figure 11 comprises to position the extraction fan and to fixate the ventilation duct. The function of the adapter unit 12 in Figure 12 comprises to position the extraction fan and to fixate the ventilation duct and to guide air from the outdoors to the indoor installation space. The function of the adapter unit 12 in Figure 13 comprises to position the extraction fan and to fixate the ventilation duct and to guide air from the outdoors directly to the inside of the non-gastight frigorific box 110.

[0087] Furthermore, regarding the concentric pipe, concentric pipe configurations may be interpreted as creating multiple functional openings within one physical opening or aperture.

[0088] According to several examples of the present disclosure, one or more of the following additional features may be considered. Namely, the non-gastight frigorific box can also be provided with sensors to detect a possible leakage of the refrigerant. Further, the non-gastight frigorific box can also be provided with acoustic insulation mounted to the sheet metal panels of the non-gastight frigorific box. The top, left, right, front, and back walls of the non-gastight frigorific box may all contain acoustic insulation foam on a surface facing inside the non-gastight frigorific box. There may be no acoustic insulation foam inside the non-gastight frigorific box attached to the bottom wall.

[0089] According to several examples of the present disclosure, having two exhaust holes instead of one helps in achieving the required minimum exhaust air flow rate stated in standard IEC 60335-2-40:2022 EXV, formulas GG.16 and GG.17 of Annex GG.4. The advantage of this solution is that a smaller fan with less electrical consumption can be chosen which positively affects the (S)COP and (S)EER of the heat pump unit.

[0090] According to several examples of the present disclosure, the non-gastight frigorific box may be made of sheet metal walls (also referred to as sheet metal plates) which are riveted together. The exhaust holes in the sheet metal wall may be laser cut or punched. The non-gastight frigorific box may be manufactured as a subassembly, tested, and then assembled into the final heat pump unit assembly. The sheet metal plates may be made by bending, deep drawing or stamping for example. Wherein corners may be welded to ensure leaked refrigerant does not escape through said corners.

[0091] According to several examples of the present disclosure, a gasket is placed in a groove in the EPP housing. The plastic support presses against this gasket. The gasket is kept in place by both the EPP housing and the plastic support. The plastic support is screwed onto the outer sheet metal casing and the EPP is attached to the non-gastight frigorific box sheet metal casing. The non-gastight frigorific box is fixed to supports of the heat pump unit's casing or housing. Hence, the design of the non-gastight frigorific box, in particular by placing the two release openings on, preferably, the back wall, is very reliable in terms of maintaining the gasket in place during production and maintenance of the non-gastight frigorific box.

Examples

Embodiment Construction

[0061]According to several examples of the present disclosure, there is described a design of a non-gastight volumetric body, for example a non-gastight frigorific box. Hence, the entire refrigerant circuit of a heat pump unit may be surrounded by a sheet metal box, called the non-gastight frigorific box as it contains sufficient and large enough openings, for example a first opening and a second opening, to not be sealed, i.e. to not be gastight. As outlined below in detail, it is important that the design of the non-gastight frigorific box is not gastight.

[0062]The non-gastight volumetric body or, in particular, the non-gastight frigorific box enables to address at least some of the drawbacks nowadays available in commonly known solutions for reducing risks of flammable refrigerants that may leak from a refrigerant circuit of a heat pump unit.

[0063]According to several examples of the present disclosure and with reference to Figures 1 to 3, some features of the non-gastight frigor...

Claims

1. A volumetric body (110) for a heat pump unit (100) operable with a flammable refrigerant, wherein the volumetric body (110) houses at least part of a refrigerant circuit (120) of the heat pump unit (100) and, when the volumetric body (110) is installed in an operation position, the volumetric body (110) is defined by a bottom wall (111), a top wall (112) and a side wall (113) of the volumetric body (110) and is a gas-tight volumetric body except for a first opening (114) and a second opening (115), the first opening (114) is provided in one of the bottom wall (111), the top wall (112) and the side wall (113), the second opening (115) is provided in one of the bottom wall (111), the top wall (112) and the side wall (113), the first opening (114) and the second opening (115) are configured for gaseous communication between an inside (Ins) and an outside (Out1; Out2; Out3) of the volumetric body (110), and a first distance (D1) from the first opening (114) to the bottom wall (111) is equal to or larger than a second distance (D2) from the second opening (115) to the bottom wall (111), wherein the first opening (114) and the second opening (115) are further configured for discharging a flammable refrigerant to an outside (Out1; Out2; Out3) of the volumetric body (110) in case of a flammable refrigerant leak inside (Ins) the volumetric body (110).

2. The volumetric body (110) according to claim 1, wherein, in case of a flammable refrigerant leak inside (Ins) the volumetric body (110), the first opening (114) is further configured for air to flow from an outside (Out1; Out2; Out3) of the volumetric body (110) into the volumetric body (110).

3. The volumetric body (110) according to claim 1 or 2, wherein the volumetric body (100) is of a prism shape, wherein the bottom wall (111) represents a bottom face, wherein the top wall (112) represents a top face, and wherein the side wall (113) comprises a plurality of faces (113-1; 113-2; 113-3; 113-4) that are side faces of the prism shape, and wherein the first opening (114) and the second opening (115) are arranged at a same face, or wherein the first opening (114) and the second opening (115) are arranged at different faces.

4. The volumetric body (110) according to any of claims 1 to 3, wherein the first distance (D1) is a smallest distance from the first opening (114) to the bottom wall (111), and wherein the second distance (D2) is a largest distance from the second opening (115) to the bottom wall (111).

5. The volumetric body (110) according to any of claims 1 to 4, wherein the first opening (114) has a minimum cross-sectional area of at least 500 mm2, and / or wherein the second opening (115) has a minimum cross-sectional area of at least 500 mm2.

6. The volumetric body (110) according to any of claims 1 to 5, further comprising a fan for promoting gaseous flow out of the volumetric body (110) through at least one of the first opening (114) and the second opening (115).

7. The volumetric body (110) according to claim 6, wherein the volumetric body (110) has a pressure difference between the inside (Ins) and an outside (Out1; Out2; Out3) equal to a pressure difference in the range of 20 Pa - 100 Pa, preferably 30 Pa.

8. The volumetric body (110) according to any of claims 1 to 7, wherein the volumetric body (110) is a frigorific box housing at least part of the refrigerant circuit (120) of the heat pump unit (100).

9. A heat pump unit (100) operable with a flammable refrigerant, preferably propane, wherein the heat pump unit (100) comprises: a housing, a refrigerant circuit (120), and a volumetric body (110) according to any of claims 1 to 8 that is installed inside the housing, wherein the housing houses the refrigerant circuit (120) and the volumetric body (110), the volumetric body (110) houses at least part of the refrigerant circuit (120), when the heat pump unit (100) is installed in an operation position, the housing of the heat pump unit (100) comprises a housing bottom wall (101), a housing top wall (102) and a housing side wall (103; 103-1), the housing comprises a first heat pump unit opening (104) and a second heat pump unit opening (105), the first heat pump unit opening (104) is provided in one of the housing bottom wall (101), the housing top wall (102) and the housing side wall (103; 103-1), the second heat pump unit opening (105) is provided in one of the housing bottom wall (101), the housing top wall (102) and the housing side wall (103; 103-1), the first heat pump unit opening (104) and the second heat pump unit opening (105) are configured for gaseous communication between an inside (Ins; Out1) and an outside (Out2; Out3) of the heat pump unit (100), and the first heat pump unit opening (104) is in gaseous communication with the first opening (114) of the volumetric body (110) and the second heat pump unit opening (105) is in gaseous communication with the second opening (115) of the volumetric body (110).

10. The heat pump unit (100) according to claim 9, wherein the first heat pump unit opening (104) is connected to the first opening (114) of the volumetric body (110), so that gas flowing into and / or out of the volumetric body (110) through the first opening (114) enters and / or exits the housing via the first heat pump unit opening (104) , and wherein the second heat pump unit opening (105) is connected to the second opening (115) of the volumetric body (110), so that gas flowing out of and / or into the volumetric body (110) through the second opening (115) exits and / or enters the housing via the second heat pump unit opening (105).

11. The heat pump unit (100) according to claim 9 or 10, wherein the housing bottom wall (101) represents a housing bottom face, wherein the housing top wall (102) represents a housing top face, and wherein the housing side wall (103) comprises a plurality of housing side faces (103-1), and wherein the first heat pump unit opening (104) and the second heat pump unit opening (105) are arranged at a same housing face, or wherein the first heat pump unit opening (104) and the second heat pump unit opening (105) are arranged at different housing faces.

12. The heat pump unit (100) according to any of claims 9 to 11, wherein a distance between the side wall (113) and the housing side wall (103) is at least 5 mm.

13. The heat pump unit (100) according to any of claims 9 to 12, wherein the heat pump unit (100) further comprises a ventilation duct (130) connected to the second heat pump unit opening (105) for gas to flow out of the volumetric body (110) into the ventilation duct (130) through the second heat pump unit opening (105), wherein: a) the ventilation duct (130) is a regular pipe, a fan is provided in the second heat pump unit opening (105), and gas flows from a space (Out2) outside of the heat pump unit (100) and inside an installation space of the heat pump unit (100) into the volumetric body (110) through the first heat pump unit opening (104); or b) the ventilation duct (130) is surrounded by a concentric pipe that is not connected to the second heat pump unit opening (105) but opens to a space (Out2) outside of the heat pump unit (100) and inside an installation space of the heat pump unit (100), a fan is provided in the second heat pump unit opening (105), gas flows from a space (Out3) outside the installation space of the heat pump unit (100) through the concentric pipe into the space (Out2) outside of the heat pump unit (100) and inside the installation space of the heat pump unit (100), and gas flows from the space (Out2) outside of the heat pump unit (100) and inside the installation space of the heat pump unit (100) into the volumetric body (110) through the first heat pump unit opening (104); or c) the ventilation duct (130) is surrounded by a concentric pipe that is connected to the second heat pump unit opening (105), a fan is provided in the second heat pump unit opening (105), gas flows from a space (Out3) outside the installation space of the heat pump unit (100) through the concentric pipe into the volumetric body (110) through the second heat pump unit opening (104), and gas flows from the space (Out2) outside of the heat pump unit (100) and inside the installation space of the heat pump unit (100) into the volumetric body (110) through the first heat pump unit opening (104).

14. Use of the volumetric body (110) according to any of claims 1 to 8.

15. Use of the heat pump unit (100) according to any of claims 9 to 13.

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