Refrigeration device

Abstract

This refrigeration device comprises a refrigerant unit (U) having a first refrigerant circuit (R1) that performs a refrigeration cycle using a first refrigerant, which is a highly flammable refrigerant, wherein: the first refrigerant circuit (R1) has a first refrigerant pipe (27a) that connects a first heat exchanger (23) and a pressure reducing mechanism (24), a second refrigerant pipe (27b) that connects the pressure reducing mechanism (24) and a second heat exchanger (22), a third refrigerant pipe (27c) that connects the second heat exchanger (22) and a compressor (21), and a fourth refrigerant pipe (27d) that connects the compressor (21) and the first heat exchanger (23); and the first to fourth refrigerant pipes (27a to 27d) are configured such that a first volume, which is the sum of the volume of the first refrigerant pipe (27a) and the volume of the second refrigerant pipe (27b), is smaller than a second volume, which is the sum of the volume of the third refrigerant pipe (27c) and the volume of the fourth refrigerant pipe (27d).

Description

Refrigeration device

[0001] The present disclosure relates to a refrigeration device.

[0002] The hot water supply unit disclosed in Patent Document 1 has a refrigerant circuit having a first heat exchanger and a second heat exchanger, and a tank for hot water supply. The hot water supply unit stores water heated by the refrigerant in the refrigerant circuit in the tank.

[0003] Japanese Patent Application Laid-Open No. 2004-132647

[0004] By the way, when the refrigerant filled in the refrigerant circuit is a flammable refrigerant, particularly a highly flammable refrigerant, from the viewpoint of refrigerant leakage and the like, it is preferable that the amount of refrigerant filled is small.

[0005] An object of the present disclosure is to reduce the amount of highly flammable refrigerant filled in the refrigerant circuit.

[0006] A first aspect includes a refrigerant unit (U) having a first refrigerant circuit (R1) that performs a refrigeration cycle using a first refrigerant that is a highly flammable refrigerant, and a casing (60) that houses the refrigerant unit (U) and is disposed in a target space (I). In the first refrigerant circuit (R1), a compressor unit (CU) having a compressor (21), a first heat exchanger (23) that exchanges heat between the first refrigerant in the first refrigerant circuit (R1) and a first heat medium flowing through a first heat medium circuit (W), a decompression mechanism (24), and a second heat exchanger (22) that exchanges heat between the first refrigerant in the first refrigerant circuit (R1) and a second heat medium flowing through a second heat medium circuit (R2) are connected in sequence. A first refrigerant pipe (27a) connecting the first heat exchanger (23) and the decompression mechanism (24), a second refrigerant pipe (27b) connecting the decompression mechanism (24) and the second heat exchanger (22), a third refrigerant pipe (27c) connecting the second heat exchanger (22) and the compressor unit (CU), and a fourth refrigerant pipe (27d) connecting the compressor unit (CU) and the first heat exchanger (23) are configured such that a first volume, which is the sum of the volume of the first refrigerant pipe (27a) and the volume of the second refrigerant pipe (27b), is smaller than a second volume, which is the sum of the volume of the third refrigerant pipe (27c) and the volume of the fourth refrigerant pipe (27d).

[0007] When the refrigeration cycle is performed in the first refrigerant circuit (R1), the first heat exchanger (23) functions as a heat radiator, and the second heat exchanger (22) functions as an evaporator. The refrigerant discharged from the compressor unit (CU) flows through the fourth refrigerant piping (27d), the refrigerant that has been released heat in the first heat exchanger (23) flows through the first refrigerant piping (27a), the refrigerant that has been depressurized by the depressurization mechanism (24) flows through the second refrigerant piping (27b), and the refrigerant that has evaporated in the second heat exchanger (22) flows through the third refrigerant piping (27c). In the first embodiment, the first volume, which is the sum of the volume of the first refrigerant piping (27a) and the volume of the second refrigerant piping (27b), is made smaller than the second volume, which is the sum of the volume of the third refrigerant piping (27c) and the volume of the fourth refrigerant piping (27d). The density of the refrigerant flowing through the first refrigerant piping (27a) and the second refrigerant piping (27b) is higher than the density of the refrigerant flowing through the third refrigerant piping (27c) and the fourth refrigerant piping (27d). Therefore, by making the volume of refrigerant flowing through the first refrigerant piping (27a) and the second refrigerant piping (27b) smaller than the volume of refrigerant flowing through the third refrigerant piping (27c) and the fourth refrigerant piping (27d), the weight of the refrigerant flowing through the first refrigerant piping (27a) and the second refrigerant piping (27b) can be reduced, and consequently, the amount of refrigerant to be filled into the first refrigerant circuit (R1) can also be reduced.

[0008] In a second aspect, in the first aspect, the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) is shorter than the sum of the lengths of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d).

[0009] In the second embodiment, if the inner diameters of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) are smaller than the inner diameters of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d), the first volume can be made smaller than the second volume. Furthermore, even if the inner diameters of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) are the same as the inner diameters of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d), the first volume can still be made smaller than the second volume.

[0010] A third embodiment is the first or second embodiment, wherein the length of the first refrigerant piping (27a) is shorter than the length of the second refrigerant piping (27b).

[0011] In the third embodiment, since the refrigerant in the first refrigerant piping (27a) is denser than the refrigerant in the second refrigerant piping (27b), the amount of refrigerant to be filled into the first refrigerant circuit (R1) can be reduced by making the first refrigerant piping (27a) shorter than the second refrigerant piping (27b).

[0012] A fourth aspect is the third aspect, wherein the pressure reducing mechanism (24) is an expansion valve with adjustable opening, and has an upper connection portion (24a) to which the first refrigerant piping (27a) is connected, and a lower connection portion (24b) located below the upper connection portion (24a) to which the second refrigerant piping (27b) is connected, and in a view of the casing (60) from the side, the first heat exchanger (23) has a first refrigerant piping connection portion (23a) connected to the first refrigerant piping (27a) extending from the upper connection portion (24a), and the second heat exchanger (22) has a second refrigerant piping connection portion (22a) connected to the second refrigerant piping (27b) extending from the lower connection portion (24b). The first refrigerant piping connection (23a) is located at a higher height than the lower connection (24b), and the second refrigerant piping connection (22a) is located at a lower height than the lower connection (24b).

[0013] In the fourth embodiment, in the pressure reducing mechanism (24), the upper connection part (24a) is positioned above the lower connection part (24b). By making the height position of the first refrigerant piping connection part (23a) higher than the height position of the second refrigerant piping connection part (22a), the distance from the upper connection part (24a) to the first refrigerant piping connection part (23a) and the distance from the lower connection part (24b) to the second refrigerant piping connection part (22a) can be shortened. In other words, the lengths of the first refrigerant piping (27a) and the second refrigerant piping (27b) can be shortened.

[0014] In the fifth embodiment, as in the fourth embodiment, the height position of the bottom surface (23b) of the first heat exchanger (23) is higher than the height position of the bottom surface (22b) of the second heat exchanger (22).

[0015] In the fifth embodiment, since the first refrigerant piping connection (23a) is located at a higher height than the second refrigerant piping connection (22a), the same effect as in the fourth embodiment can be obtained.

[0016] The sixth embodiment is that, in any one of the first to fourth embodiments, when the casing (60) is viewed from above, the first heat exchanger (23) and the second heat exchanger (22) are arranged facing each other with the pressure reducing mechanism (24) in between, and the shortest distance D1 between the first heat exchanger (23) and the second heat exchanger (22) is shorter than the shortest distance D2 between the first heat exchanger (23) and the compressor unit (CU) or the shortest distance D3 between the second heat exchanger (22) and the compressor unit (CU).

[0017] In the sixth embodiment, by making D1 shorter than D2 or D3, the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) can be made shorter than the length of the third refrigerant pipe (27c) or the fourth refrigerant pipe (27d).

[0018] The seventh embodiment is that in any one of the first to fourth embodiments, when the casing (60) is viewed from above, the first heat exchanger (23) and the second heat exchanger (22) are each positioned facing the pressure reducing mechanism (24), the second heat exchanger (22) is positioned near one end of the first heat exchanger (23) in the longitudinal direction, and the shortest distance D1 between the first heat exchanger (23) and the second heat exchanger (22) is shorter than the shortest distance D2 between the first heat exchanger (23) and the compressor unit (CU) or the shortest distance D3 between the second heat exchanger (22) and the compressor unit (CU).

[0019] In the seventh embodiment, by making D1 shorter than D2 or D3, the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) can be made shorter than the length of the third refrigerant pipe (27c) or the fourth refrigerant pipe (27d).

[0020] The eighth aspect is that in any one of the first to fourth aspects, when the casing (60) is viewed from above, the longitudinal direction of the first heat exchanger (23) coincides with the longitudinal direction of the second heat exchanger (22), the first heat exchanger (23) and the second heat exchanger (22) are arranged adjacent to each other, and the shortest distance D1 between the first heat exchanger (23) and the second heat exchanger (22) is shorter than the shortest distance D2 between the first heat exchanger (23) and the compressor unit (CU) or the shortest distance D3 between the second heat exchanger (22) and the compressor unit (CU).

[0021] In the eighth embodiment, by making D1 shorter than D2 or D3, the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) can be made shorter than the length of the third refrigerant pipe (27c) or the fourth refrigerant pipe (27d).

[0022] In the ninth embodiment, in any one of the first to eighth embodiments, the refrigerant unit (U) and the first heat transfer circuit (W) are arranged adjacent to each other in the horizontal direction.

[0023] In the ninth embodiment, the refrigerant unit (U) and the water circuit (W) can be arranged separately in the horizontal direction. This makes it easier to remove only the refrigerant unit (U).

[0024] The tenth aspect is the ninth aspect, wherein the casing (60) houses a third heat exchanger (26) connected to the first heat transfer medium circuit (W) and which exchanges heat between the first heat transfer medium and the second heat transfer medium, and the third heat exchanger (26) is positioned in the vicinity of the first heat exchanger (23).

[0025] In the tenth embodiment, by arranging the third heat exchanger (26) near the first heat exchanger (23), the length of the piping between the first water heat exchanger (23) and the third heat exchanger (26) can be shortened, and heat loss from the water flowing between the first water heat exchanger (23) and the third heat exchanger (26) can be suppressed.

[0026] The eleventh aspect is the tenth aspect, wherein, in a view of the casing (60) from above, the first heat exchanger (23) and the second heat exchanger (22) are positioned closer to the first side surface (63) of the casing (60) than to the center of the casing (60).

[0027] In the eleventh embodiment, the first heat exchanger (23) and the second heat exchanger (22) are positioned closer to one side (the first side (63)) of the casing (60) than to the center, making it possible to create a layout that facilitates the removal of the refrigerant unit (U).

[0028] The twelfth embodiment is one of the first to eleventh embodiments, wherein the compressor unit (CU) comprises an accumulator (25) connected in the middle of the suction pipe provided in the compressor (21).

[0029] In the twelfth embodiment, an accumulator (25) can be provided in the refrigeration device.

[0030] The thirteenth embodiment is one of the first to twelfth embodiments, wherein the first heat transfer medium is water, and further comprises a tank (41) for storing the first heat transfer medium that has been heat-exchanged with the first refrigerant, and the refrigerant unit (U) and the tank (41) are arranged vertically side by side within the casing (60).

[0031] Figure 1 is a piping diagram of the hot water supply system of an embodiment. Figure 2 is a perspective view showing the external appearance of the hot water supply unit. Figure 3 is a schematic plan view showing the arrangement of equipment in the first space. Figure 4 is a plan view of the first space showing the relative distances between the first water heat exchanger, the refrigerant heat exchanger, and the compressor. Figure 5 is a schematic diagram showing the connection state of the first water heat exchanger, the first expansion valve, and the refrigerant heat exchanger, as well as the first and second refrigerant piping, in a view of the casing from the side. Figure 6 is a plan view of the first space showing the relative distances between the first water heat exchanger, the refrigerant heat exchanger, and the compressor in Modification 1. Figure 7 is a plan view of the first space showing the relative distances between the first water heat exchanger, the refrigerant heat exchanger, and the compressor in Modification 2. Figure 8 is a plan view of the first space showing the relative distances between the first water heat exchanger, the refrigerant heat exchanger, and the compressor in Modification 3. Figure 9 is a diagram corresponding to Figure 1 showing the piping system of the hot water supply system in Modification 4. Figure 10 is a plan view corresponding to Figure 3, which schematically shows the arrangement of equipment in the first space. Figure 11 is a schematic diagram of another embodiment, showing the connection state of the first water heat exchanger, the first expansion valve, and the refrigerant heat exchanger, as well as the first and second refrigerant piping, in a view of the casing from the side.

[0032] Embodiments of this disclosure will be described in detail below with reference to the drawings. This disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual illustration of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

[0033] (1) Configuration of the hot water supply system (1-1) Overall configuration The hot water supply system (1) supplies hot water to the target. The target of this embodiment includes hot water supply targets such as faucets, showers, and baths, as well as a heating device (5) that uses hot water. The hot water supply system (1) is connected to the hot water supply targets and the heating device (5) via water piping. The hot water supply system (1) has an outdoor unit (10) located outside and a hot water supply unit (20) located inside. The hot water supply system (1) is an example of a refrigeration device (1).

[0034] The hot water supply system (1) has a circuit configuration consisting of a first refrigerant circuit (R1), a second refrigerant circuit (R2), and a water circuit (W). The first refrigerant circuit (R1) is filled with a highly flammable refrigerant as the first refrigerant. The second refrigerant circuit (R2) is filled with carbon dioxide as the second refrigerant. The second refrigerant circuit (R2) is an example of a second heat transfer medium circuit, and carbon dioxide is an example of a second heat transfer medium. The water circuit (W) is an example of a first heat transfer medium circuit, and the water flowing through the water circuit (W) is an example of a first heat transfer medium.

[0035] The first refrigerant is propane (R290), a highly flammable natural refrigerant. Natural refrigerants have zero ozone depletion potential and a low global warming potential, making them environmentally friendly. Propane ignites at temperatures below 500°C. The first refrigerant may be a single refrigerant consisting of one type of refrigerant, or a mixed refrigerant consisting of two or more types of refrigerants.

[0036] The hot water supply system (1) includes a refrigerant heat exchanger (22), a first water heat exchanger (23), and a second water heat exchanger (26). The refrigerant heat exchanger (22) is shared by the first refrigerant circuit (R1) and the second refrigerant circuit (R2), the first water heat exchanger (23) is shared by the first refrigerant circuit (R1) and the water circuit (W), and the second water heat exchanger (26) is shared by the second refrigerant circuit (R2) and the water circuit (W). The refrigerant heat exchanger (22) is an example of the second heat exchanger, and the first water heat exchanger (23) is an example of the first heat exchanger. The hot water supply system (1) performs a so-called binary refrigeration cycle using the first refrigerant circuit (R1) and the second refrigerant circuit (R2).

[0037] (1-2) Outdoor Unit The outdoor unit (10) has part of the second refrigerant circuit (R2). The outdoor unit (10) has a second compressor (11), an outdoor heat exchanger (12), a second expansion valve (13), a four-way switching valve (14), and a second accumulator (15) as components of the second refrigerant circuit (R2). The outdoor unit (10) has an outdoor fan (16). The second compressor (11) compresses the inhaled refrigerant and discharges the compressed refrigerant. The outdoor heat exchanger (12) exchanges heat between the outdoor air transported by the outdoor fan (16) and the second refrigerant. The second expansion valve (13) reduces the pressure of the refrigerant. The four-way switching valve (14) switches between a first state shown by the solid line in Figure 1 and a second state shown by the dashed line in Figure 1. The second accumulator (15) stores the liquid refrigerant before it is drawn into the second compressor (11).

[0038] (1-3) Circuit Configuration of Hot Water Supply Unit The hot water supply unit (20) is an example of a refrigerant unit (U). The hot water supply unit (20) has the entirety of a first refrigerant circuit (R1). The hot water supply unit (20) has a first compressor (21), a refrigerant heat exchanger (22), a first water heat exchanger (23), a first expansion valve (24), and a first accumulator (25) as elemental components of the first refrigerant circuit (R1). The first compressor (21) and the first accumulator (25) constitute a compressor unit (CU). The first accumulator (25) is an example of an accumulator of this disclosure. The first compressor (21) has a discharge pipe and an intake pipe (not shown). The first compressor (21) compresses the refrigerant drawn in from the intake pipe and discharges the compressed refrigerant through the discharge pipe. The first compressor (21) is an example of a compressor (21) of this disclosure.

[0039] The refrigerant heat exchanger (22) has a first flow path (P1) connected to a first refrigerant circuit (R1) and a second flow path (P2) connected to a second refrigerant circuit (R2). The refrigerant heat exchanger (22) exchanges heat between the first refrigerant in the first flow path (P1) of the first refrigerant circuit (R1) and the second refrigerant in the second flow path (P2) of the second refrigerant circuit (R2). The refrigerant heat exchanger (22) is an example of a second heat exchanger (22).

[0040] The first water heat exchanger (23) has a third flow path (P3) connected to the first refrigerant circuit (R1) and a fourth flow path (P4) connected to the water circuit (W). The first water heat exchanger (23) exchanges heat between the first refrigerant in the third flow path (P3) of the first refrigerant circuit (R1) and the water in the fourth flow path (P4) of the water circuit (W). The first water heat exchanger (23) is an example of the first heat exchanger (23).

[0041] The first expansion valve (24) is an example of a pressure reducing mechanism for reducing the pressure of the refrigerant. The first expansion valve (24) is configured to allow adjustment of its opening. The first accumulator (25) stores liquid refrigerant. The first accumulator (25) is connected to the upstream side of the first compressor (21). The first accumulator (25) is located in the middle of the suction pipe. The first accumulator (25) separates the refrigerant flowing through the suction pipe into gaseous and liquid refrigerant. The refrigerant heat exchanger (22) and the first water heat exchanger (23) are composed of, for example, plate heat exchangers.

[0042] The first refrigerant circuit (R1) includes a first refrigerant pipe (27a), a second refrigerant pipe (27b), a third refrigerant pipe (27c), and a fourth refrigerant pipe (27d). The first refrigerant pipe (27a) connects the first water heat exchanger (23) to the first expansion valve (24). The second refrigerant pipe (27b) connects the first expansion valve (24) to the refrigerant heat exchanger (22). The third refrigerant pipe (27c) connects the refrigerant heat exchanger (22) to the compressor unit (CU). In this embodiment, the third refrigerant pipe (27c) connects the refrigerant heat exchanger (22) to the first accumulator (25). The fourth refrigerant pipe (27d) connects the compressor unit (CU) to the first water heat exchanger (23). In this embodiment, the fourth refrigerant pipe (27d) connects the first compressor (21) and the first water heat exchanger (23).

[0043] The inner diameters of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) are the same. The inner diameters of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d) are the same. The inner diameters of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) are smaller than the inner diameters of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d). Hereinafter, the first refrigerant pipe (27a) and the second refrigerant pipe (27b) may be collectively referred to as the liquid refrigerant pipe (27a, 27b). Also, the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d) may be collectively referred to as the gas refrigerant pipe (27c, 27d).

[0044] The hot water supply unit (20) has a part of the second refrigerant circuit (R2). As an element device of the second refrigerant circuit (R2), the hot water supply unit (20) has a second water heat exchanger (26) in addition to the first water heat exchanger (23) described above. The second water heat exchanger (26) is an example of the third heat exchanger (26). The second water heat exchanger (26) is connected to the water circuit (W) and exchanges heat between the second heat medium and the water in the water circuit (W). Specifically, the second water heat exchanger (26) has a fifth flow path (P5) connected to the second refrigerant circuit (R2) and a sixth flow path (P6) connected to the water circuit (W). The second water heat exchanger (26) exchanges heat between the second refrigerant in the fifth flow path (P5) of the second refrigerant circuit (R2) and the water in the sixth flow path (P6) of the water circuit (W). The second water heat exchanger (26) is composed of, for example, a plate heat exchanger.

[0045] The hot water supply unit (20) has a first pipe (31), a second pipe (32), a third pipe (33), and a bypass pipe (34) as refrigerant piping constituting the second refrigerant circuit (R2). One end of the first pipe (31) is connected to the gas side line of the second refrigerant circuit (R2). The other end of the first pipe (31) is connected to one end of the fifth flow path (P5) of the second water heat exchanger (26). One end of the second pipe (32) is connected to the other end of the fifth flow path (P5) of the second water heat exchanger (26). The other end of the second pipe (32) is connected to one end of the second flow path (P2) of the refrigerant heat exchanger (22). One end of the third pipe (33) is connected to the other end of the second flow path (P2) of the refrigerant heat exchanger (22). The other end of the third pipe (33) is connected to the liquid side line of the second refrigerant circuit (R2). One end of the bypass pipe (34) is connected to the middle section of the first pipe (31). The other end of the bypass pipe (34) is connected to the middle section of the second pipe (32). The first pipe (31) is provided with a first on-off valve (35) between the connection point of the bypass pipe (34) and the fifth flow path (P5). The bypass pipe (34) is provided with a second on-off valve (36).

[0046] The hot water supply unit (20) has a part of the water circuit (W). In addition to the first water heat exchanger (23) and the second water heat exchanger (26) described above, the hot water supply unit (20) has a first pump (40), a tank (41), and an internal heat exchanger (42) as components of the water circuit (W).

[0047] The first pump (40) circulates the water in the water circuit (W). Figure 1 shows the direction of water circulation in the water circuit (W) with arrows.

[0048] The tank (41) stores water (strictly speaking, warm water) to be supplied to the target. The tank (41) is a hollow container, and a hot water storage space (41a) is formed inside it. A water supply pipe (43) and a hot water outlet pipe (44) are connected to the tank (41). One end of the water supply pipe (43) is connected to the bottom of the tank (41), and the other end of the water supply pipe (43) is connected to a water pipe. When the water in the tank (41) decreases, the water supply pipe (43) supplies low-temperature water in the water pipe into the tank (41). One end of the hot water outlet pipe (44) is connected to the upper part of the tank (41), and the other end of the hot water outlet pipe (44) is connected to a predetermined hot water supply target. The hot water outlet pipe (44) supplies high-temperature water in the tank (41) to hot water supply targets such as faucets, showers, and bathtubs.

[0049] The internal heat exchanger (42) is disposed in the hot water storage space (41a). The internal heat exchanger (42) in the present embodiment is a heat transfer pipe formed in a spiral shape. Warm water heated by the first water heat exchanger (23) and the second water heat exchanger (26) flows inside the internal heat exchanger (42). The internal heat exchanger (42) exchanges heat between the warm water flowing inside it and the water around it. As a result, the water in the hot water storage space (41a) is heated by the internal heat exchanger (42). Thus, the tank (41) in the present embodiment stores water indirectly heated by the first refrigerant of the first water heat exchanger (23).

[0050] The water circuit (W) has a main flow path (50), a hot water supply side flow path (51), and a heating side flow path (52). The inflow end of the hot water supply side flow path (51) and the inflow end of the heating side flow path (52) are connected to the outflow end of the main flow path (50). A three-way valve (53) is connected to the water circuit (W). The three-way valve (53) switches between a first state in which the main flow path (50) and the hot water supply side flow path (51) are in communication and a second state in which the main flow path (50) and the heating side flow path (52) are in communication.

[0051] A first pump (40), the fourth flow path (P4) of the first water heat exchanger (23), and the sixth flow path (P6) of the second water heat exchanger (26) are sequentially connected to the main flow path (50).

[0052] The hot water supply side flow path (51) has an inflow pipe (51a) and an outflow pipe (51b). An internal heat exchanger (42) is connected between the inflow pipe (51a) and the outflow pipe (51b).

[0053] The heating-side flow path (52) is connected to the user-side heat exchanger (6) of the heating device (5). The user-side heat exchanger (6) heats the air in the target space (indoor space). The user-side heat exchanger (6) consists of a fin-and-tube type heat exchanger or a radiant panel. The user-side heat exchanger (6) consists of an air heat exchanger that directly heats the air in the target space, or a heat exchanger for floor heating that heats the floor of the target space.

[0054] The hot water supply unit (20) has a supply pipe (52a) and a return pipe (52b) as part of the heating side flow path (52). The supply pipe (52a) is a flow path for supplying hot water heated in the first water heat exchanger (23) and the second water heat exchanger (26) to the utilization side heat exchanger (6). The return pipe (52b) is a flow path for returning the water that has been heated in the utilization side heat exchanger (6) back to the main flow path (50).

[0055] The hot water supply unit (20) further includes a heater unit (54) and an expansion tank (55) as equipment elements of the water circuit (W). The heater unit (54) is installed in the main flow path (50) and provides auxiliary heating of the water in the water circuit (W). The expansion tank (55) communicates with the main flow path (50) and mitigates the rise in water pressure in the water circuit (W).

[0056] (2) Structure of the hot water supply unit The structure of the hot water supply unit (20) will be explained with reference to Figures 1 to 4. In the following explanation, terms such as up, down, front, back, right, and left will be based on the directions indicated by the arrows in Figure 2.

[0057] (2-1) Casing As shown in Figure 2, the hot water supply system (1) has a casing (60) that is placed in the interior space (I). The interior space (I) is a space formed inside the building and includes not only living spaces but also non-living spaces such as corridors, basements, warehouses, and garages. The casing (60) is installed on the floor surface of the interior space (I). The interior space (I) is an example of the target space (I). The casing (60) houses the refrigerant unit (U), the second water heat exchanger (26), the tank (41), etc.

[0058] The casing (60) is formed in the shape of a hollow box. The casing (60) has a rectangular parallelepiped shape. The vertical height of the casing (60) is greater than the front-to-back length and left-to-right width of the casing (60). The casing (60) has a top plate (61), a bottom plate (62), a front plate (63), a rear plate (64), a right plate (65), and a left plate (66). The top plate (61) constitutes the upper surface of the casing (60), and the bottom plate (62) constitutes the lower surface of the casing (60). The front plate (63) constitutes the front surface, which is the first side surface of the casing (60).

[0059] A partition plate (67) is provided inside the casing (60). The partition plate (67) divides the inside of the casing (60) vertically. Specifically, the partition plate (67) divides the inside of the casing (60) into a first space (S1) and a second space (S2). The first space (S1) is formed in the lower part of the casing (60). The second space (S2) is formed from the middle to the upper part of the casing (60). The first space (S1) and the second space (S2) are formed in the shape of a rectangular parallelepiped. The height of the second space (S2) is greater than the height of the first space (S1). A tank (41) is placed in the second space (S2).

[0060] In the installed state of the casing (60), a workspace (S3) is secured in front of the casing (60). An access opening (A) is formed at the bottom of the front plate (63) of the casing (60). An opening / closing cover (68), which is part of the front plate (63), is detachably attached to the access opening (A). The worker can access the first space (S1) inside the casing (60) from the workspace (S3) through the access opening (A).

[0061] (2-2) Arrangement of each piece of equipment in the first space The first space (S1) is where the equipment of the hot water supply unit (20) described above is arranged. As shown in Figure 3, the first space (S1) is where a refrigerant unit (U) having a first refrigerant circuit (R1) is arranged. The refrigerant unit (U) includes the entire first refrigerant circuit (R1) as a closed circuit. The refrigerant unit (U) has a first compressor (21), a refrigerant heat exchanger (22), a first expansion valve (24), and a first water heat exchanger (23) as elemental components of the first refrigerant circuit (R1).

[0062] The refrigerant unit (U) is positioned closer to the front plate (63) than to the rear plate (64). The refrigerant unit (U) is positioned closer to the left plate (66) than to the right plate (65). The first compressor (21) is positioned near the access port (A). The first compressor (21) is visible from outside the casing (60) through the access port (A) when the opening / closing cover (68) is removed. The refrigerant unit (U) is located below the tank (41). The refrigerant unit (U) overlaps with the tank (41) in the vertical direction.

[0063] The refrigerant heat exchanger (22) and the first water heat exchanger (23) are located behind the first compressor (21). In this embodiment, the refrigerant heat exchanger (22) is located to the right of the first water heat exchanger (23).

[0064] The hot water supply unit (20) has a support member (70) that supports the refrigerant unit (U). The support member (70) is located below the refrigerant unit (U) and supports the refrigerant unit (U) from below. The support member (70) is configured to be retractable from the access opening (A) along the bottom plate (62). It is preferable that the bottom plate (62) be provided with a guide member that guides the support member (70) in the front-rear direction.

[0065] An electrical component unit (71) is provided in the first space (S1). The electrical component unit (71) is positioned below the tank (41). The electrical component unit (71) overlaps with the tank (41) in the vertical direction.

[0066] The electrical components unit (71) includes a control board for controlling each component of the hot water supply unit (20). The electrical components unit (71) is located near the access opening (A). When the opening / closing cover (68) is removed, the electrical components unit (71) is visible from outside the casing (60) through the access opening (A).

[0067] The second water heat exchanger (26) is located behind the electrical equipment unit (71). A first shut-off valve (35) and a second shut-off valve (36) are located between the second water heat exchanger (26) and the electrical equipment unit (71). A first pipe (31) and a third pipe (33), which are refrigerant pipes, are located around the second water heat exchanger (26). The first pipe (31) and the third pipe (33) penetrate the partition plate (67) and extend vertically through the first space (S1).

[0068] In the first space (S1), a connection space (75) is formed behind the electrical component unit (71). The connection space (75) is formed towards the front of the first space (S1). A first connection part (C1), a second connection part (C2), a third connection part (C3), and a fourth connection part (C4) are arranged in the connection space (75).

[0069] The first connection part (C1) and the second connection part (C2) constitute a water-side connection part that detachably connects the first water heat exchanger (23) and the water circuit (W). As shown in Figure 1, the first connection part (C1) connects the water piping on the inflow side of the fourth flow path (P4) of the first water heat exchanger (23) to the water circuit (W). The second connection part (C2) connects the water piping on the outflow side of the fourth flow path (P4) of the first water heat exchanger (23) to the water circuit (W). The first connection part (C1) is closer to the front plate (63) than to the rear plate (64). The second connection part (C2) is closer to the front plate (63) than to the rear plate (64). The first connection part (C1) and the second connection part (C2) are arranged side by side in the left-right direction along the back of the electrical component unit (71). Thus, the refrigerant unit (U) is positioned horizontally adjacent to the water circuit (W).

[0070] The third connection (C3) and the fourth connection (C4) constitute the heat transfer medium side connection that detachably connects the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). As shown in Figure 1, the third connection (C3) connects the refrigerant piping upstream of the second flow path (P2) of the refrigerant heat exchanger (22) to the second refrigerant circuit (R2). The third connection (C3) is closer to the front plate (63) than to the rear plate (64). The fourth connection (C4) is located behind the third connection (C3). The third connection (C3), like the fourth connection (C4), may be located closer to the front plate (63) than to the rear plate (64).

[0071] In the first space (S1), the components of the water circuit (W) are arranged behind the refrigerant unit (U) and connection space (75). A water circuit side space (76) is formed. The water circuit side space (76) is formed towards the rear of the first space (S1). The first pump (40), heater unit (54), three-way valve (53), and expansion tank (55) are arranged in the water circuit side space (76). The water piping in the water circuit side space (76) is arranged as an inlet pipe (51a), an outlet pipe (51b), a supply pipe (52a), and a return pipe (52b).

[0072] The inlet pipe (51a) and outlet pipe (51b) pass through the partition plate (67) and connect to the internal heat exchanger (42) in the tank (41). The supply pipe (52a) and return pipe (52b) pass through the partition plate (67) and extend vertically through the first space (S1).

[0073] Although not shown in the diagram, other equipment for the water circuit (W) is arranged in the first space (S1). The other equipment includes drain valves, ball valves, flow sensors, and filters. It is preferable that the other equipment be positioned closer to the front plate (63) than to the rear plate (64).

[0074] (3) Regarding the first refrigerant circuit, the first refrigerant circuit (R1) in this embodiment is configured such that the volume inside the liquid refrigerant pipes (27a, 27b) is smaller than the volume inside the gas refrigerant pipes (27c, 27d). In other words, the first to fourth refrigerant pipes (27a to 27d) constituting the first refrigerant circuit (R1) are configured such that the first volume, which is the sum of the volume of the first refrigerant pipe (27a) and the volume of the second refrigerant pipe (27b), is smaller than the second volume, which is the sum of the volume of the third refrigerant pipe (27c) and the volume of the fourth refrigerant pipe (27d). In this embodiment, the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) is shorter than the sum of the lengths of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d).

[0075] Specifically, as shown in Figure 4, when viewing the casing (60) from above, the shortest distance between the refrigerant heat exchanger (22) and the first water heat exchanger (23) is defined as D1, the shortest distance between the first water heat exchanger (23) and the compressor unit (CU) is defined as D2, and the shortest distance between the refrigerant heat exchanger (22) and the compressor unit (CU) is defined as D3. In this embodiment, D2 is the shortest distance between the first water heat exchanger (23) and the first compressor (21), and D3 is the shortest distance between the refrigerant heat exchanger (22) and the first accumulator (25). Thus, the first compressor (21) and the first accumulator (25) are arranged such that D1 is shorter than D2 and D3.

[0076] Here, D1 refers to the shortest length of the straight line connecting the midpoint or a point near the midpoint in the longitudinal direction of the refrigerant heat exchanger (22) and the midpoint or a point near the midpoint in the longitudinal direction of the first water heat exchanger (23), when viewed from above on the casing (60). D2 refers to the shortest length of the straight line connecting the midpoint or a point near the midpoint in the longitudinal direction of the first water heat exchanger (23) to the cylindrical center of the first compressor (21), when viewed from above on the casing (60). D3 refers to the shortest length of the straight line connecting the midpoint or a point near the midpoint in the longitudinal direction of the refrigerant heat exchanger (22) to the cylindrical center of the first accumulator (25), when viewed from above on the casing (60). A point near the midpoint refers to a point within ±10% of the midpoint when the longitudinal length of the refrigerant heat exchanger (22) or the first water heat exchanger (23) is taken as 100%.

[0077] In this embodiment, when viewed from above through the casing (60), the refrigerant heat exchanger (22) and the first water heat exchanger (23) are arranged facing each other with the first expansion valve (24) in between. The first expansion valve (24) is positioned closer to the first water heat exchanger (23) than to the refrigerant heat exchanger (22). In other words, the length of the first refrigerant piping (27a) is shorter than the length of the second refrigerant piping (27b).

[0078] (4) Regarding the first refrigerant piping and the second refrigerant piping, as shown in Figure 5, the first expansion valve (24) has an upper connection part (24a) and a lower connection part (24b). The first refrigerant piping (27a) is connected to the upper connection part (24a). The second refrigerant piping (27b) is connected to the lower connection part (24b). In the first expansion valve (24), the lower connection part (24b) is provided below the upper connection part (24a).

[0079] The first water heat exchanger (23) has a first refrigerant piping connection (23a) to which the first refrigerant piping (27a) extending from the upper connection (24a) is connected. The refrigerant heat exchanger (22) has a second refrigerant piping connection (22a) to which the second refrigerant piping (27b) extending from the lower connection (24b) is connected. When the casing (60) is viewed from the side, the first water heat exchanger (23), the first expansion valve (24), and the refrigerant heat exchanger (22) are arranged in order from left to right, and the height of the first refrigerant piping connection (23a) is higher than the height of the second refrigerant piping connection (22a).

[0080] The bottom surface (22b) of the refrigerant heat exchanger (22) and the bottom surface (23b) of the first water heat exchanger (23) are at the same height. In other words, the refrigerant heat exchanger (22) and the first water heat exchanger (23) are fixed within the casing (60) with their respective bottom surfaces (22b, 23b) at the same height. Even if the upper connection part (24a) of the first expansion valve (24) is at a higher height than the lower connection part (24b), the first refrigerant piping connection part (23a) is at a higher height than the second refrigerant piping connection part (22a), thus preventing the lengths of the first refrigerant piping (27a) and the second refrigerant piping (27b) from becoming excessively long.

[0081] Here, if the refrigerant heat exchanger (22) and the first water heat exchanger (23) have a casing, the bottom surface (22b) of the refrigerant heat exchanger (22) and the bottom surface (23b) of the first water heat exchanger (23) mean the bottom surface of the casing. Also, if the refrigerant heat exchanger (22) and the first water heat exchanger (23) are plate heat exchangers in which a plurality of plates are arranged horizontally, the bottom surfaces of the refrigerant heat exchanger (22) and the first water heat exchanger (23) may mean the surfaces in contact with the lower ends of each of the plurality of plates. Also, if the refrigerant heat exchanger (22) and the first water heat exchanger (23) are plate heat exchangers in which a plurality of plates are stacked vertically, the bottom surfaces of the refrigerant heat exchanger (22) and the first water heat exchanger (23) may be the plates located at the lower ends. Furthermore, when the refrigerant heat exchanger (22) and the first water heat exchanger (23) are fixed to the bottom surface of the casing (60), the bottom surfaces of the refrigerant heat exchanger (22) and the first water heat exchanger (23) may be the parts that are fixed to the bottom surface of the casing. In this case, the bottom surface of the casing may be a support member (70). Alternatively, the refrigerant heat exchanger (22) and the first water heat exchanger (23) may be attached to the bottom surface of the casing via an insulating material. In this case, the bottom surfaces of the refrigerant heat exchanger (22) and the first water heat exchanger (23) may be the surfaces of the insulating material that are in contact with the bottom surface of the casing or the support member (70).

[0082] (5) Operation of the hot water supply system (1) During operation, the second refrigerant circuit (R2) performs a subcritical or supercritical cycle while the first refrigerant circuit (R1) performs a subcritical cycle. The second refrigerant circuit (R2) switches between the first and second operations. The water circuit (W) switches between the third and fourth operations.

[0083] In the first operation, the four-way switching valve (14) enters the first state, the first on-off valve (35) enters the open state, and the second on-off valve (36) enters the closed state. In the first operation, the refrigerant compressed by the second compressor (11) dissipates heat in the second water heat exchanger (26) and the refrigerant heat exchanger (22), is depressurized by the second expansion valve (13), and evaporates in the outdoor heat exchanger (12).

[0084] In the second operation, the four-way switching valve (14) enters the first state, the first on-off valve (35) enters the closed state, and the second on-off valve (36) enters the open state. In the second operation, the refrigerant compressed by the second compressor (11) bypasses the second water heat exchanger (26), dissipates heat in the refrigerant heat exchanger (22), is depressurized by the second expansion valve (13), and evaporates in the outdoor heat exchanger (12).

[0085] In the first refrigerant circuit (R1), the refrigerant compressed by the first compressor (21) dissipates heat in the first water heat exchanger (23), is depressurized in the first expansion valve (24), and evaporates in the refrigerant heat exchanger (22).

[0086] In the third operation, the three-way valve (53) enters the first state. In the third operation, the water transported by the first pump (40) is heated either in the first water heat exchanger (23) only, or in both the second water heat exchanger (26) and the first water heat exchanger (23). After heating, the water releases heat to the water in the hot water storage space (41a) in the internal heat exchanger (42). As a result, hot water is generated in the tank (41).

[0087] In the fourth operation, the three-way valve (53) enters the second state. In the fourth operation, the water transported by the first pump (40) is heated either in the first water heat exchanger (23) only, or in both the second water heat exchanger (26) and the first water heat exchanger (23). After heating, the water releases heat into the air of the target space in the user-side heat exchanger (6) of the heating device (5), resulting in the target space being heated.

[0088] (6) Features (6-1) Feature 1 The refrigeration device (1) of this embodiment comprises a refrigerant unit (U) having a first refrigerant circuit (R1) that performs a refrigeration cycle using a first refrigerant which is a highly flammable refrigerant, and a casing (60) that houses the refrigerant unit (U) and is arranged in the target space (I). The first refrigerant circuit (R1) is sequentially connected to a first compressor (21), a first water heat exchanger (23) that exchanges heat between the first refrigerant of the first refrigerant circuit (R1) and water flowing through a water circuit (W), a first expansion valve (24), and a refrigerant heat exchanger (22) that exchanges heat between the first refrigerant of the first refrigerant circuit (R1) and carbon dioxide flowing through a second refrigerant circuit (R2). The refrigerant piping of the first refrigerant circuit (R1) includes a first refrigerant pipe (27a) connecting the first water heat exchanger (23) and the first expansion valve (24), a second refrigerant pipe (27b) connecting the first expansion valve (24) and the refrigerant heat exchanger (22), a third refrigerant pipe (27c) connecting the refrigerant heat exchanger (22) and the first compressor (21), and a fourth refrigerant pipe (27d) connecting the first compressor (21) and the first water heat exchanger (23). The first to fourth refrigerant pipes (27a to 27d) are configured such that the first volume, which is the sum of the volume of the first refrigerant pipe (27a) and the volume of the second refrigerant pipe (27b), is smaller than the second volume, which is the sum of the volume of the third refrigerant pipe (27c) and the volume of the fourth refrigerant pipe (27d).

[0089] In this case, if the refrigerant is a highly flammable refrigerant such as propane, it is preferable to minimize the amount (weight) of refrigerant filled into the first refrigerant circuit (R1) from the viewpoint of preventing refrigerant leakage into the indoor space (I). However, if the amount of refrigerant is reduced too much, the cooling capacity of the first refrigerant circuit (R1) cannot be fully utilized.

[0090] Therefore, it is necessary to reduce the amount of refrigerant filled into the first refrigerant circuit (R1) while ensuring the required refrigerant capacity. Here, the density of the refrigerant in the first refrigerant circuit (R1) is higher for liquid refrigerant than for gaseous refrigerant. Therefore, if the volume inside the liquid refrigerant piping (27a, 27b) of the first refrigerant circuit (R1) increases, the amount of refrigerant that needs to be filled will also increase accordingly.

[0091] Focusing on these points, the hot water supply unit of this embodiment is configured such that the first volume, which is the sum of the volumes of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) in the first refrigerant circuit (R1), is smaller than the second volume, which is the sum of the volumes of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d). As a result, the volume of refrigerant flowing through the first refrigerant pipe (27a) and the second refrigerant pipe (27b) can be made smaller than the volume of refrigerant flowing through the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d). Consequently, the amount of refrigerant (refrigerant weight) flowing through the liquid refrigerant pipes (27a, 27b) can be reduced, and therefore the amount of refrigerant to be filled into the first refrigerant circuit (R1) can also be reduced, while ensuring the required refrigeration capacity of the first refrigerant circuit (R1).

[0092] (6-2) Feature 2 In the refrigeration system (1) of this embodiment, the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) is shorter than the sum of the lengths of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d). In this embodiment, since the inner diameters of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) are smaller than the inner diameters of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d), the first volume can be made smaller than the second volume.

[0093] (6-3) Feature 3 In the refrigeration system (1) of this embodiment, the length of the first refrigerant pipe (27a) is shorter than the length of the second refrigerant pipe (27b). During the refrigeration cycle operation of the first refrigerant circuit (R1), the refrigerant passing through the first refrigerant pipe (27a) is depressurized by the first expansion valve (24) and flows into the second refrigerant pipe (27b). Thus, the density of the refrigerant flowing through the first refrigerant pipe (27a) is higher than the density of the refrigerant flowing through the second refrigerant pipe (27b). Therefore, by making the first refrigerant pipe (27a) shorter than the second refrigerant pipe (27b), the amount of refrigerant (refrigerant weight) to be filled into the first refrigerant circuit (R1) can be reduced.

[0094] (6-4) Feature 4 In this embodiment, the first expansion valve (24) has an upper connection part (24a) to which the first refrigerant pipe (27a) is connected, and a lower connection part (24b) located below the upper connection part (24a) to which the second refrigerant pipe (27b) is connected. When the casing (60) is viewed from the side, the first heat exchanger (23) has a first refrigerant pipe connection part (23a) connected to the first refrigerant pipe (27a) extending from the upper connection part (24a), and the second heat exchanger (22) has a second refrigerant pipe connection part (22a) connected to the second refrigerant pipe (27b) extending from the lower connection part (24b). The first refrigerant pipe connection part (23a) is located at a higher height than the second refrigerant pipe connection part (22a).

[0095] Since the upper connection (24a) is positioned above the lower connection (24b), the distance from the upper connection (24a) to the first refrigerant piping connection (23a) and the distance from the lower connection (24b) to the second refrigerant piping connection (22a) can be shortened by raising the height of the first refrigerant piping connection (23a) higher than the height of the second refrigerant piping connection (22a). In other words, the lengths of the first refrigerant piping (27a) and the second refrigerant piping (27b) can be shortened.

[0096] (6-5) Feature 5 In the hot water supply system (1) of this embodiment, when the casing (60) is viewed from above, the first water heat exchanger (23) and the refrigerant heat exchanger (22) are arranged to face each other with the first expansion valve (24) in between, and the shortest distance D1 between the first water heat exchanger (23) and the refrigerant heat exchanger (22) is shorter than the shortest distance D2 between the first water heat exchanger (23) and the first compressor (21) of the compressor unit (CU), and the shortest distance D3 between the refrigerant heat exchanger (22) and the first accumulator (25) of the compressor unit (CU).

[0097] By arranging the first water heat exchanger (23), the first expansion valve (24), and the refrigerant heat exchanger (22) sequentially in the lateral direction of the casing (60) in this manner, and by making D1 shorter than D2 and D3, the first volume can be made smaller than the second volume.

[0098] (6-6) Feature 6 In the hot water supply system (1) of this embodiment, the refrigerant unit (U) and the water circuit (W) are arranged adjacent to each other in the horizontal direction. In this way, the refrigerant unit (U) and the water circuit (W) can be arranged separately in the horizontal direction. With this arrangement, only the refrigerant unit (U) can be removed by pulling it out horizontally from the casing (60) through the access port (A).

[0099] (6-7) Feature 7 The hot water supply system (1) of this embodiment further includes a tank (41) for storing water that has been heat-exchanged with the first refrigerant, and the refrigerant unit (U) is arranged below the tank (41) in the casing (60). By arranging the refrigerant unit (U) below the tank (41), the center of gravity of the hot water supply unit (20) can be positioned lower. This improves the stability of the installation of the hot water supply unit (20).

[0100] (7) Modified Examples Modified examples of the hot water supply system (1) of the above embodiment will be described below. Only configurations that differ from the above embodiment will be described below.

[0101] (7-1) Modification 1 As shown in Figure 6, in the hot water supply system (1) of Modification 1, when viewed from above with the casing (60), the first water heat exchanger (23) and the refrigerant heat exchanger (22) are each positioned facing the first expansion valve (24), and the refrigerant heat exchanger (22) is positioned near one end of the first water heat exchanger (23) in the longitudinal direction. The compressor unit (CU) of Modification 1 is also positioned so that D1 is shorter than D2 and D3.

[0102] Specifically, when viewing the casing (60) from above, the first water heat exchanger (23) and the refrigerant heat exchanger (22) are arranged such that the longitudinal direction of the first water heat exchanger (23) and the longitudinal direction of the refrigerant heat exchanger (22) are perpendicular to each other, and one end of the first water heat exchanger (23) and one end of the refrigerant heat exchanger (22) are close to each other. The first expansion valve (24) is positioned to face both the first water heat exchanger (23) and the refrigerant heat exchanger (22), thereby shortening the liquid refrigerant piping (27a, 27b). Close proximity means that, when viewing the casing (60) from above, the shortest distance between one end of the first water heat exchanger (23) and one end of the refrigerant heat exchanger (22) is shorter than the longitudinal length of either the first water heat exchanger (23) or the refrigerant heat exchanger (22). In this modified example, the shortest distance between one end of the first water heat exchanger (23) in the longitudinal direction and one end of the refrigerant heat exchanger (22) is 5 mm to 10 mm.

[0103] As a result, in the hot water supply unit (20) of the modified example 1, the liquid refrigerant piping (27a, 27b) can be made shorter than the gas refrigerant piping (27c, 27d). Consequently, the first volume becomes smaller than the second volume, so the amount of refrigerant (refrigerant weight) flowing through the liquid refrigerant piping (27a, 27b) can be reduced, and the required refrigeration capacity can be secured while suppressing the amount of refrigerant to be filled into the first refrigerant circuit (R1).

[0104] (7-2) Modified Example 2 As shown in Figure 7, in the hot water supply system (1) of Modified Example 2, when viewed from above with the casing (60), the longitudinal direction of the first water heat exchanger (23) coincides with the longitudinal direction of the refrigerant heat exchanger (22), and the first water heat exchanger (23) and the refrigerant heat exchanger (22) are arranged adjacent to each other. Specifically, the first end (23c), which is one end of the longitudinal direction of the first water heat exchanger (23), is positioned so that it faces the second end (22c), which is one end of the longitudinal direction of the refrigerant heat exchanger (22), when they are close together. In addition, the compressor unit (CU) of Modified Example 2 is also arranged so that D1 is shorter than D2 and D3.

[0105] This allows the first water heat exchanger (23) and the refrigerant heat exchanger (22) to be placed close to each other, thus making the first refrigerant piping (27a) and the second refrigerant piping (27b) relatively short. Close proximity means that, when viewed from above with the casing (60), the distance between the first end (23c) and the second end (22c) is shorter than the longitudinal length of the first water heat exchanger (23) and the refrigerant heat exchanger (22). Specifically, the distance between the first end (23c) and the second end (22c) is preferably 5 mm to 10 mm.

[0106] In the refrigeration system of the modified example 2, the first volume can be made smaller than the second volume, so the amount of refrigerant (refrigerant weight) flowing through the liquid refrigerant piping (27a, 27b) can be reduced, and the required refrigeration capacity can be secured while suppressing the amount of refrigerant to be filled into the first refrigerant circuit (R1).

[0107] (7-3) Modification 3 As shown in Figure 8, in the hot water supply system (1) of Modification 3, the second water heat exchanger (26) is positioned near the first water heat exchanger (23). Specifically, when viewing the casing (60) from above, the first water heat exchanger (23), the second water heat exchanger (26), and the refrigerant heat exchanger (22) are positioned closer to the front plate (63) than to the center of the casing (60).

[0108] Here, proximity means that the shortest distance between the second heat exchanger (26) and the first heat exchanger (23) is shorter than the longitudinal length of either the second heat exchanger (26) or the first heat exchanger (23) when viewed from above through the casing (60).

[0109] In the refrigeration system (1) of the modified example 3, the first water heat exchanger (23) and the refrigerant heat exchanger (22) are positioned closer to the front, making it easier to remove the refrigerant unit (U) from the access port (A). In addition, the proximity of the first water heat exchanger (23) and the second heat exchanger (22) allows for a shorter piping length between the first water heat exchanger (23) and the second water heat exchanger (26), thereby reducing heat loss from the water flowing between the first water heat exchanger (23) and the second water heat exchanger (26).

[0110] (7-4) Modification 4 As shown in Figures 9 and 10, the hot water supply system (1) of Modification 4 has a Water Source Heat Pump (WSHP). The second heat transfer medium circuit (R2) of Modification 4 differs from the second refrigerant circuit (R2) of the above embodiment. The second heat exchanger (22) of the second heat transfer medium circuit (R2) of Modification 4 is a water heat exchanger that exchanges heat between a refrigerant and water. The second heat transfer medium is water. The second heat transfer medium may be brine. In Modification 4, the second heat exchanger (22) is called the third water heat exchanger (22). In the second heat transfer medium circuit (R2), water heated by an externally located heat source device (not shown) circulates.

[0111] The hot water supply unit (20) of modified example 4 has a first pipe (81), a second pipe (82), and a second pump (45). The first pipe (81) and the second pipe (82) constitute a second heat transfer medium circuit (R2). The first pipe (81) transports water heated by the heat source device to the second heat exchanger (22). The first pipe (81) is connected to the inflow side of the second flow path (P2) of the second heat exchanger (22). Specifically, the first pipe (81) is connected to a third connection (C3). The second pipe (82) transports water that has undergone heat exchange in the second heat exchanger (22) toward the heat source device. Specifically, the second pipe (82) is connected to a fourth connection (C4). The second pump (45) transports water in the second heat transfer medium circuit (R2). Water circulates in the second heat transfer medium circuit (R2) due to the operation of the second pump (45). The second pump (45) is installed in the second piping (82).

[0112] As shown in Figure 10, the compressor unit (CU), the first water heat exchanger (23), and the third water heat exchanger (22) are positioned closer to the rear plate (64) in the casing (60). Specifically, the compressor unit (CU), the first water heat exchanger (23), and the third water heat exchanger (22) are positioned facing each other towards the rear plate (64). The compressor unit (CU) is positioned closer to the right end, and the refrigerant first water heat exchanger (23) and the third water heat exchanger (22) are positioned adjacent to each other in the left-right direction.

[0113] (8) Other Embodiments As shown in Figure 11, the height of the bottom surface (23b) of the first heat exchanger (23) may be higher than the height of the bottom surface (22b) of the second heat exchanger (22). Since the height of the first refrigerant piping connection (23a) is higher than that of the second refrigerant piping connection (22a), the distance from the upper connection (24a) to the first refrigerant piping connection (23a) and the distance from the lower connection (24b) to the second refrigerant piping connection (22a) can be shortened.

[0114] The first refrigerant can be any highly flammable refrigerant and is not limited to propane.

[0115] The first heat transfer medium can be any heat transfer medium that can exchange heat with the first refrigerant, and it does not have to be water.

[0116] The second heat transfer medium is not limited to carbon dioxide, but may be other refrigerants (e.g., HFC refrigerants or HFO refrigerants). Alternatively, the second heat transfer medium may be water or brine. In this case, the second refrigerant circuit (R2) may be configured to exchange heat with geothermal energy. Specifically, a portion of the piping constituting the second refrigerant circuit (R2) is placed underground.

[0117] The hot water supply system (1) may also be a system that supplies hot water from the tank (41) only to the heating device (5).

[0118] The hot water supply unit (20) does not need to have a second water heat exchanger (26). In this case, the second refrigerant circuit (R2) will have a configuration in which the second water heat exchanger (26), bypass pipe (34), first shut-off valve (35), and second shut-off valve (36) are omitted.

[0119] The water heated in the first water heat exchanger (23) may be directly stored in the tank (41). In other words, the tank (41) may store water that has been directly heated by the first refrigerant.

[0120] Within the casing (60), the refrigerant unit (U) may be positioned below the tank (41). In other words, within the casing (60), the tank (41) may be positioned above the refrigerant unit (U).

[0121] The refrigeration system (1) may also be configured without the outdoor unit (10).

[0122] The first refrigerant circuit (R1) only needs to be configured such that the first volume is smaller than the second volume, and the sum of the lengths of the first refrigerant piping (27a) and the second refrigerant piping (27b) may be equal to or shorter than the sum of the lengths of the third refrigerant piping (27c) and the fourth refrigerant piping (27d). Also, the length of the first refrigerant piping (27a) may be shorter than the length of the second refrigerant piping (27b).

[0123] The compressor unit (CU) may include other components instead of the first accumulator (25). In that case, D3 may be the shortest distance between the component and the first water heat exchanger (23). Alternatively, the compressor unit (CU) may have only the first compressor (21). In that case, D3 is the shortest distance between the first compressor (21) and the first water heat exchanger (23).

[0124] D2 may be the shortest distance between the first accumulator (25) and the refrigerant heat exchanger (22) in the compressor unit (CU). D3 may be the shortest distance between the first compressor (21) and the first water heat exchanger (23) in the compressor unit (CU).

[0125] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, these embodiments and modifications may be combined or substituted as appropriate, as long as they do not impair the functions of the subject matter of this disclosure. The terms “first,” “second,” etc., described above are used to distinguish the phrases to which these terms are attached and do not limit the number or order of such phrases.

[0126] As explained above, this disclosure is useful for refrigeration equipment.

[0127] 1 Hot water supply system (refrigeration device) 21 First compressor (compressor) 22 Refrigerant heat exchanger (second heat exchanger) 22 Third water heat exchanger (second heat exchanger) 23 First water heat exchanger (first heat exchanger) 24 First expansion valve (pressure reducing mechanism) 24a Upper connection 24b Lower connection 26 Second water heat exchanger (third heat exchanger) 27a First refrigerant piping 27b Second refrigerant piping 27c Third refrigerant piping 27d Fourth refrigerant piping 41 Tank 60 Casing 63 Front panel (first side) CU Compressor unit I Interior space (target space) R1 First refrigerant circuit R2 Second refrigerant circuit (second heat transfer medium circuit) U Refrigerant unit W Water circuit (first heat transfer medium circuit)

Claims

1. The refrigeration unit (U) has a first refrigeration circuit (R1) that performs a refrigeration cycle using a first refrigerant which is a highly flammable refrigerant, and a casing (60) that houses the refrigerant unit (U) and is placed in the target space (I), wherein the first refrigerant circuit (R1) is sequentially connected to a compressor unit (CU) having a compressor (21), a first heat exchanger (23) that exchanges heat between the first refrigerant in the first refrigerant circuit (R1) and a first heat transfer medium flowing through a first heat transfer medium circuit (W), a pressure reducing mechanism (24), and a second heat exchanger (22) that exchanges heat between the first refrigerant in the first refrigerant circuit (R1) and a second heat transfer medium flowing through a second heat transfer medium circuit (R2). A refrigeration system in which a first refrigerant pipe (27a) connecting the first heat exchanger (23) and the pressure reducing mechanism (24), a second refrigerant pipe (27b) connecting the pressure reducing mechanism (24) and the second heat exchanger (22), a third refrigerant pipe (27c) connecting the second heat exchanger (22) and the compressor unit (CU), and a fourth refrigerant pipe (27d) connecting the compressor unit (CU) and the first heat exchanger (23) are configured such that a first volume, which is the sum of the volume of the first refrigerant pipe (27a) and the volume of the second refrigerant pipe (27b), is smaller than a second volume, which is the sum of the volume of the third refrigerant pipe (27c) and the volume of the fourth refrigerant pipe (27d).

2. The refrigeration apparatus according to claim 1, wherein the sum of the lengths of the first refrigerant pipe (27a) and the second refrigerant pipe (27b) is shorter than the sum of the lengths of the third refrigerant pipe (27c) and the fourth refrigerant pipe (27d).

3. The refrigeration apparatus according to claim 1 or 2, wherein the length of the first refrigerant pipe (27a) is shorter than the length of the second refrigerant pipe (27b).

4. The pressure reducing mechanism (24) is an expansion valve with adjustable opening, and has an upper connection portion (24a) to which the first refrigerant piping (27a) is connected, and a lower connection portion (24b) located below the upper connection portion (24a) to which the second refrigerant piping (27b) is connected, and in a view of the casing (60) from the side, the first heat exchanger (23) has a first refrigerant piping connection portion (23a) connected to the first refrigerant piping (27a) extending from the upper connection portion (24a), and the second heat exchanger (22) has a second refrigerant piping connection portion (22a) connected to the second refrigerant piping (27b) extending from the lower connection portion (24b), The refrigeration apparatus according to claim 3, wherein the first refrigerant piping connection (23a) is located at a higher height than the lower connection (24b), and the second refrigerant piping connection (22a) is located at a lower height than the lower connection (24b).

5. The refrigeration apparatus according to claim 4, wherein the height of the bottom surface (23b) of the first heat exchanger (23) is higher than the height of the bottom surface (22b) of the second heat exchanger (22).

6. The refrigeration apparatus according to any one of claims 1 to 4, wherein, in a view of the casing (60) from above, the first heat exchanger (23) and the second heat exchanger (22) are arranged facing each other with the pressure reducing mechanism (24) in between, and the shortest distance D1 between the first heat exchanger (23) and the second heat exchanger (22) is shorter than the shortest distance D2 between the first heat exchanger (23) and the compressor unit (CU) or the shortest distance D3 between the second heat exchanger (22) and the compressor unit (CU).

7. The refrigeration apparatus according to claim 1 or 2, wherein, in a view of the casing (60) from above, the first heat exchanger (23) and the second heat exchanger (22) are each positioned facing the pressure reducing mechanism (24), and the second heat exchanger (22) is positioned near one end of the first heat exchanger (23) in the longitudinal direction, and the shortest distance D1 between the first heat exchanger (23) and the second heat exchanger (22) is shorter than the shortest distance D2 between the first heat exchanger (23) and the compressor unit (CU) or the shortest distance D3 between the second heat exchanger (22) and the compressor unit (CU).

8. The refrigeration apparatus according to any one of claims 1 to 4, wherein, in a view of the casing (60) from above, the longitudinal direction of the first heat exchanger (23) coincides with the longitudinal direction of the second heat exchanger (22), the first heat exchanger (23) and the second heat exchanger (22) are arranged adjacent to each other, and the shortest distance D1 between the first heat exchanger (23) and the second heat exchanger (22) is shorter than the shortest distance D2 between the first heat exchanger (23) and the compressor unit (CU) or the shortest distance D3 between the second heat exchanger (22) and the compressor unit (CU).

9. The refrigeration apparatus according to any one of claims 1 to 8, wherein the refrigerant unit (U) and the first heat transfer medium circuit (W) are arranged adjacent to each other in the horizontal direction.

10. The refrigeration apparatus according to claim 9, wherein the casing (60) is connected to the first heat transfer medium circuit (W) and houses a third heat exchanger (26) that exchanges heat between the first heat transfer medium and the second heat transfer medium, and the third heat exchanger (26) is located near the first heat exchanger (23).

11. The refrigeration apparatus according to claim 10, wherein, in a view of the casing (60) from above, the first heat exchanger (23) and the second heat exchanger (22) are positioned closer to the first side surface (63) of the casing (60) than to the center of the casing (60).

12. The refrigeration apparatus according to any one of claims 1 to 11, wherein the compressor unit (CU) is connected to an accumulator (25) in the middle of a suction pipe provided in the compressor (21).

13. The refrigeration apparatus according to any one of claims 1 to 12, wherein the first heat transfer medium is water, and further comprises a tank (41) for storing the first heat transfer medium that has been heat-exchanged with the first refrigerant, and the refrigerant unit (U) and the tank (41) are arranged vertically side by side within the casing (60).

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