JP7606121B1 - Refrigeration equipment - Google Patents

Abstract

The present invention provides a refrigeration system having two refrigerant circuits using different refrigerants, and solves the problem of drainage in a heat exchanger.
[Solution] The refrigeration device 10 comprises a first refrigerant circuit that circulates a first refrigerant, a second refrigerant circuit that circulates a second refrigerant different from the first refrigerant, and a third heat exchanger that exchanges heat between the first refrigerant and the second refrigerant, the first refrigerant circuit includes a first heat exchanger 26 having a circular tubular heat transfer tube 26b, the second refrigerant circuit 22 includes a second heat exchanger 36 having a flat multi-hole tube 36b, the first heat exchanger 26 and the second heat exchanger 36 are arranged next to each other above and below, and the second heat exchanger 36 is arranged above the first heat exchanger 26.
[Selected figure] Figure 3

Description

This disclosure relates to a refrigeration device.

Patent Document 1 discloses a dual-stage refrigeration system having a low-stage refrigeration cycle and a high-stage refrigeration cycle. The low-stage refrigeration cycle is used to adjust the temperature of an indoor load device, such as a showcase. For this reason, the low-stage refrigeration cycle uses a refrigerant such as carbon dioxide, which has a low global warming potential, since the refrigerant circuit may be opened due to rearrangement of the showcase, etc., which may cause refrigerant leakage. In contrast, the high-stage refrigeration cycle is used to further cool the refrigerant cooled by the radiator of the low-stage refrigeration cycle. Unlike the refrigerant circuit of the low-stage refrigeration cycle, the refrigerant circuit of the high-stage refrigeration cycle is never opened, so a refrigerant such as R32, which has a higher global warming potential but higher heat exchange efficiency than the refrigerant of the low-stage refrigeration cycle, is used.

International Publication No. 2014/181399

Refrigerants such as R32 used in high-temperature refrigeration cycles can be flammable and toxic, so it is desirable to use as little of them as possible. For this reason, it is considered to use a heat exchanger equipped with flat multi-hole tubes that can perform heat exchange more efficiently with a smaller amount of refrigerant than a heat exchanger equipped with a typical circular heat transfer tube. However, this heat exchanger has problems with drainage, as water tends to accumulate on the flat multi-hole tubes.

The purpose of this disclosure is to solve the problem of drainage in a heat exchanger in a refrigeration system equipped with two refrigerant circuits using different refrigerants.

(1) A refrigeration device according to the present disclosure includes a first refrigerant circuit that circulates a first refrigerant;
a second refrigerant circuit that circulates a second refrigerant different from the first refrigerant;
a third heat exchanger for exchanging heat between the first refrigerant and the second refrigerant,
The first refrigerant circuit includes a first heat exchanger having a circular heat transfer tube,
the second refrigerant circuit includes a second heat exchanger having flat multi-hole tubes;
The first heat exchanger and the second heat exchanger are arranged vertically side by side,
The second heat exchanger is disposed above the first heat exchanger.

With this configuration, since the second heat exchanger is disposed above the first heat exchanger, water does not drip from the first heat exchanger onto the flat multi-hole tubes of the second heat exchanger. This prevents water from accumulating or freezing on the flat multi-hole tubes.

(2) In the refrigeration device of (1) above, the second heat exchanger preferably includes a plurality of the flat multi-hole tubes spaced apart in the vertical direction, and serpentine fins arranged between adjacent flat multi-hole tubes in the vertical direction.

In the second heat exchanger, if water gets into the fins, it is difficult to drain, and there is a risk that the accumulated water will freeze and damage the adhesive portion between the fins and the flat multi-hole tubes. In the refrigeration device configured as described above, the second heat exchanger is placed above the first heat exchanger, and water generated in the first heat exchanger does not drip onto the second heat exchanger, so there is less chance of water getting into the fins, and problems such as the water freezing can be prevented.

(3) In the refrigeration device of (1) or (2) above, preferably, the vertical distance between the first heat exchanger and the second heat exchanger is 10 mm or less.

This configuration makes it possible to prevent the overall size of the first heat exchanger and the second heat exchanger from increasing.

(4) In the refrigeration device described in any one of (1) to (3) above, preferably, the heat transfer tube is made of a material mainly composed of copper, and the flat multi-hole tube is made of a material mainly composed of aluminum.

Copper has a higher electric potential than aluminum, so if water generated by copper comes into contact with aluminum, there is a possibility that electrolytic corrosion will occur in the aluminum. With the above configuration, water generated in the first heat exchanger does not drip into the second heat exchanger, so that electrolytic corrosion of the flat multi-hole tube made of a material whose main component is aluminum can be suppressed.

(5) The refrigeration apparatus according to any one of (1) to (4) above preferably includes a casing that houses the first heat exchanger and the second heat exchanger;
The cooling system further includes a fan disposed above the second heat exchanger and configured to generate an airflow passing through the first heat exchanger and the second heat exchanger.

According to the above configuration, by operating the fan, the flow rate of the air flow passing through the second heat exchanger located above can be increased compared to the air flow passing through the first heat exchanger located below, making it easier to remove water adhering to the second heat exchanger with the air flow having a higher flow rate.

(6) The refrigeration device described in any one of (1) to (5) above preferably further includes a connecting member that connects the first heat exchanger and the second heat exchanger.

(7) In the refrigeration device described in (6) above, preferably, in a top view, a longitudinal end of the first heat exchanger is disposed in the vicinity of a longitudinal end of the second heat exchanger,
The connecting member includes a first connecting member connecting the end of the first heat exchanger and the end of the second heat exchanger.

(8) In the refrigeration device described in (6) or (7) above, preferably, the connecting member includes a second connecting member that connects the middle portions of the first heat exchanger and the second heat exchanger in the longitudinal direction when viewed from above.

With the above configuration, even if vibrations caused by transportation or the like are transmitted to the refrigeration device, the mid-length portion of the first heat exchanger and the mid-length portion of the second heat exchanger are less likely to vibrate in different directions, preventing the two from rubbing against each other or colliding with each other.

1 is a refrigerant circuit diagram of a refrigeration device according to a first embodiment of the present disclosure. FIG. FIG. 2 is a plan view showing the inside of the outdoor unit of the refrigeration apparatus. 3 is a diagram showing the inside of the outdoor unit as viewed from the line BB in FIG. 2 . 3 is a diagram showing the inside of the outdoor unit as viewed from the CC line arrows in FIG. 2. 3 is a diagram showing the inside of the outdoor unit as viewed from the arrows DD in FIG. 2. FIG. 2 is an explanatory diagram illustrating a schematic configuration of a first outdoor heat exchanger in the refrigeration device. FIG. 4 is an explanatory diagram illustrating a second outdoor heat exchanger in the refrigeration device. FIG. 4 is an enlarged cross-sectional view of a second outdoor heat exchanger. FIG. 2 is an explanatory diagram illustrating an arrangement of a first outdoor heat exchanger and a second outdoor heat exchanger. 10 is a cross-sectional view taken along line AA of FIG. 9. FIG. 4 is a Mollier diagram for explaining the refrigeration cycle of the first refrigerant circuit during cooling operation. 11 is a side view showing the inside of an outdoor unit in a refrigeration apparatus according to a second embodiment of the present disclosure. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
[First embodiment]
(Overall configuration of the refrigeration device)
FIG. 1 is a refrigerant circuit diagram of a refrigeration device according to a first embodiment of the present disclosure.
As shown in Fig. 1, the refrigeration device 10 of this embodiment is an air conditioner that adjusts the temperature of air in a room, which is a space to be air-conditioned, to a predetermined target temperature. The refrigeration device 10 of this embodiment cools and heats the room. However, the refrigeration device 10 may be dedicated to cooling. The refrigeration device 10 may also be a refrigerator, a freezer, or the like that cools the air inside the storage unit.

The refrigeration device 10 has an outdoor unit 11 (heat source unit) and an indoor unit 12 (utilization unit). The refrigeration device 10 has, for example, one outdoor unit 11 and one indoor unit 12 connected to the outdoor unit 11. However, the refrigeration device 10 may have multiple indoor units 12 connected in parallel to the outdoor unit 11. The refrigeration device 10 may be equipped with multiple outdoor units 11.

The refrigeration device 10 has a first refrigerant circuit 21 and a second refrigerant circuit 22. The first refrigerant circuit 21 circulates a first refrigerant, and the second refrigerant circuit 22 circulates a second refrigerant. In this embodiment, carbon dioxide is used as the first refrigerant. In this embodiment, a refrigerant that is flammable or toxic, or has a high global warming potential (GWP), is used as the second refrigerant. For example, R290 (propane) is used as the second refrigerant. The refrigeration device 10 further has an auxiliary heat exchanger 27 and a control device 51.

(Configuration of the first refrigerant circuit 21)
The first refrigerant circuit 21 circulates a first refrigerant between the indoor unit 12 and the outdoor unit 11. The first refrigerant circuit 21 includes a first compressor 24, a four-way switching valve 25, a first outdoor heat exchanger (heat source heat exchanger; first heat exchanger) 26, a first expansion valve 28, a first shut-off valve 29, an indoor heat exchanger (utilization heat exchanger) 30, a second shut-off valve 31, a first accumulator 32, and refrigerant piping 40 connecting these components.

The outdoor unit 11 is equipped with a first compressor 24, a four-way switching valve 25, a first outdoor heat exchanger 26, a first expansion valve 28, a first shut-off valve 29, a second shut-off valve 31, and a first accumulator 32 that constitute a first refrigerant circuit 21. The indoor unit 12 is equipped with an indoor heat exchanger 30 that constitutes the first refrigerant circuit 21. The outdoor unit 11 is provided with an outdoor fan 41 that takes in outdoor air into the outdoor unit 11 and supplies it to the first outdoor heat exchanger 26. The indoor unit 12 is provided with an indoor fan 42 that takes in indoor air into the indoor unit 12 and supplies it to the indoor heat exchanger 30.

The first compressor 24 draws in a low-pressure gaseous first refrigerant and discharges a high-pressure gaseous first refrigerant. The first compressor 24 is equipped with a motor whose operating speed can be adjusted by inverter control. The first compressor 24 is a variable capacity type (variable capacity type) whose capacity (capacity) can be changed by inverter control of the motor. However, the first compressor 24 may be a fixed capacity type. Multiple first compressors 24 may be provided. In this case, variable capacity compressors and fixed capacity compressors may be mixed.

The four-way switching valve 25 reverses the flow of the first refrigerant in the refrigerant piping 40, switching the first refrigerant discharged from the first compressor 24 to either the first outdoor heat exchanger 26 or the indoor heat exchanger 30. This allows the refrigeration device 10 to switch between cooling operation and heating operation.

The first outdoor heat exchanger 26 is a cross-fin tube type heat exchanger. The first outdoor heat exchanger 26 exchanges heat between the outdoor air taken in by the outdoor fan 41 and the first refrigerant, and dissipates heat or evaporates the first refrigerant.

The first expansion valve 28 is a pressure reducer that reduces the pressure of the first refrigerant and expands it. The first expansion valve 28 is configured as an electric valve that can adjust the refrigerant flow rate, etc. The first expansion valve 28 reduces the pressure of the high-pressure gaseous first refrigerant that has had heat dissipated in the first exterior heat exchanger 26 and the auxiliary heat exchanger 27 described below, and expands it to create a low-pressure gas-liquid two-phase refrigerant. A capillary tube may be used as the pressure reducer instead of the first expansion valve 28.

The first shut-off valve 29 is a manually operated on-off valve. When closed, the first shut-off valve 29 blocks the flow of the first refrigerant in the refrigerant piping 40, and when open, allows the flow of the first refrigerant in the refrigerant piping 40.

The indoor heat exchanger 30 is, for example, a cross-fin tube type or a microchannel type heat exchanger. The indoor heat exchanger 30 exchanges heat between the indoor air taken in by the indoor fan 42 and the first refrigerant, and dissipates heat or evaporates the first refrigerant.

The second shutoff valve 31 is a manually operated on-off valve. When closed, the second shutoff valve 31 blocks the flow of the first refrigerant in the refrigerant piping 40, and when open, allows the flow of the first refrigerant in the refrigerant piping 40.

The first accumulator 32 is provided in the suction pipe of the first compressor 24. The first accumulator 32 temporarily stores the low-pressure first refrigerant before it is sucked into the first compressor 24, and separates the first refrigerant into gas refrigerant and liquid refrigerant. The first refrigerant, which is the gas refrigerant separated in the first accumulator 32, is sucked into the first compressor 24.

(Configuration of the second refrigerant circuit 22)
The second refrigerant circuit 22 circulates the refrigerant inside the outdoor unit 11. The second refrigerant circuit 22 uses R290 (propane) as a second refrigerant. The second refrigerant circuit 22 includes a second compressor 34, a second outdoor heat exchanger (second heat exchanger) 36, a second expansion valve 38, a second accumulator 39, and a refrigerant pipe 50 connecting these components.

The second compressor 34 draws in a low-pressure gaseous second refrigerant and discharges a high-pressure gaseous second refrigerant. The second compressor 34 is equipped with a motor whose operating speed can be adjusted by inverter control. The second compressor 34 is a variable capacity type (variable capacity type) whose capacity (capacity) can be changed by inverter control of the motor. However, the second compressor 34 may be a fixed capacity type. Multiple second compressors 34 may be provided. In this case, a variable capacity type second compressor and a fixed capacity type second compressor may be mixed.

The second outdoor heat exchanger 36 is a microchannel type heat exchanger. The second outdoor heat exchanger 36 exchanges heat between the refrigerant and the outdoor air supplied by the outdoor fan 41, causing the refrigerant to release heat (condense).

The second expansion valve 38 is a pressure reducer that reduces the pressure of the second refrigerant to expand it. In this embodiment, the second expansion valve 38 is configured as an electric valve that can adjust the refrigerant flow rate, etc. The second expansion valve 38 reduces the pressure of the high-pressure second refrigerant that has had its heat dissipated in the second exterior heat exchanger 36 and expands it to produce a low-pressure gas-liquid two-phase refrigerant. A capillary tube may be used as a pressure reducer instead of the second expansion valve 38.

The second accumulator 39 temporarily stores the low-pressure second refrigerant before it is drawn into the second compressor 34, and separates the second refrigerant into gas refrigerant and liquid refrigerant. The second accumulator 39 is provided in the suction pipe of the second compressor 34. The second refrigerant, which is a gas refrigerant separated in the second accumulator 39, is drawn into the second compressor 34.

(Configuration of the auxiliary heat exchanger (third heat exchanger) 27)
The auxiliary heat exchanger 27 further dissipates heat from the first refrigerant that has had heat dissipated in the first exterior heat exchanger 26. The auxiliary heat exchanger 27 evaporates the second refrigerant that has had heat dissipated in the second exterior heat exchanger 36 and has been depressurized by the second expansion valve 38.

Specifically, the auxiliary heat exchanger 27 has a first heat transfer tube 27a and a second heat transfer tube 27b. One end of the first heat transfer tube 27a is connected to a refrigerant pipe extending to the first outdoor heat exchanger 26. The other end of the first heat transfer tube 27a is connected to a refrigerant pipe extending to the first expansion valve 28. One end of the second heat transfer tube 27b is connected to a refrigerant pipe extending to the second expansion valve 38. The other end of the second heat transfer tube 27b is connected to a refrigerant pipe extending to the second accumulator 39.

The auxiliary heat exchanger 27 exchanges heat between the first refrigerant flowing through the first heat transfer tube 27a and the second refrigerant flowing through the second heat transfer tube 27b. The first refrigerant (gaseous refrigerant) whose heat has been dissipated in the first outdoor heat exchanger 26 flows into the first heat transfer tube 27a. The second refrigerant (two-phase gas-liquid refrigerant) whose pressure has been reduced and expanded by the second expansion valve 38 flows into the second heat transfer tube 27b.

Therefore, the auxiliary heat exchanger 27 exchanges heat between the first refrigerant that passes through the first outdoor heat exchanger 26 and flows through the first heat transfer tube 27a, and the second refrigerant that passes through the second expansion valve (pressure reducer) 38 and flows through the second heat transfer tube 27b. The auxiliary heat exchanger 27 dissipates heat from the first refrigerant that flows through the first heat transfer tube 27a, and evaporates the second refrigerant that flows through the second heat transfer tube 27b.

As described above, the auxiliary heat exchanger 27 is included in the first refrigerant circuit 21 and the second refrigerant circuit 22. Therefore, the auxiliary heat exchanger 27 can also be said to be a component of the first refrigerant circuit 21 and the second refrigerant circuit 22.

(Configuration of control device 51)
The control device 51 controls the operation of the first compressor 24, the four-way switching valve 25, the first expansion valve 28, the outdoor fan 41, the indoor fan 42, the second compressor 34, the second expansion valve 38, and the like. The control device 51 includes a processor and a memory. The processor of the control device 51 is configured with a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a gate array, or an FPGA (Field Programmable Gate Array), and the like. The ASIC, or a programmable logic device such as a gate array or an FPGA, is configured to be able to execute the same process as the control program. The memory of the control device 51 includes a volatile memory such as an SRAM (Static Random Access Memory) or a DRAM (Dynamic Random Access Memory), and a non-volatile memory such as a flash memory, a hard disk, or a ROM (Read Only Memory). The non-volatile memory stores a control program, which is a computer program, and control data.

The control device 51 performs various functions by the processor executing a control program. Specifically, the control device 51 performs cooling operation and heating operation.

(Cooling operation)
When the refrigeration device 10 performs cooling operation, the control device 51 drives both the first refrigerant circuit 21 and the second refrigerant circuit 22. The four-way switching valve 25 is held in the state shown by the solid line in FIG. 1. The first compressor 24 of the first refrigerant circuit 21 discharges a high-temperature, high-pressure gaseous first refrigerant. The first refrigerant flows into the first outdoor heat exchanger 26 via the four-way switching valve 25. In this embodiment, the first refrigerant is carbon dioxide, and is pressurized by the first compressor 24 to a pressure exceeding the critical point. The first refrigerant exchanges heat with the outdoor air by operating the outdoor fan 41, and dissipates heat. Furthermore, the first refrigerant flows into the auxiliary heat exchanger 27.

Meanwhile, the second compressor 34 of the second refrigerant circuit 22 discharges a high-temperature, high-pressure gaseous second refrigerant. The second refrigerant flows into the second outdoor heat exchanger 36, where it exchanges heat with the outdoor air and dissipates heat (condenses) when the outdoor fan 41 is activated. The second refrigerant then flows into the second expansion valve 38, where it is reduced in pressure to a predetermined low pressure. The second refrigerant then flows into the auxiliary heat exchanger 27.

In the auxiliary heat exchanger 27, the first refrigerant in the first refrigerant circuit 21 exchanges heat with the second refrigerant in the second refrigerant circuit 22 and releases heat. The first refrigerant is then decompressed and expanded in the first expansion valve 28 and flows into the indoor heat exchanger 30 of the indoor unit 12. In the indoor unit 12, the first refrigerant exchanges heat with the indoor air in the indoor heat exchanger 30 and evaporates. The indoor air cooled by the evaporation of the first refrigerant is blown into the room by the indoor fan 42, cooling the room. The first refrigerant evaporated in the indoor heat exchanger 30 returns to the outdoor unit 11 through the refrigerant piping 40, passes through the four-way switching valve 25 and the first accumulator 32, and is sucked into the first compressor 24.

In the auxiliary heat exchanger 27, the second refrigerant in the second refrigerant circuit 22 exchanges heat with the first refrigerant in the first refrigerant circuit 21 and evaporates. The second refrigerant then passes through the second accumulator 39 and is sucked into the second compressor 34.

(Heating operation)
When the refrigeration system 10 performs heating operation, the control device 51 drives the first refrigerant circuit 21 and stops the second refrigerant circuit 22. The four-way switching valve 25 is held in the state shown by the dashed line in Fig. 1. The high-temperature, high-pressure gaseous first refrigerant discharged from the first compressor 24 passes through the four-way switching valve 25 and flows into the indoor heat exchanger 30 of the indoor unit 12. In the indoor heat exchanger 30, the first refrigerant exchanges heat with indoor air and dissipates heat. The indoor air heated by the heat dissipation of the first refrigerant is blown into the room by the indoor fan 42, heating the room.

The first refrigerant then returns to the outdoor unit 11 through the refrigerant piping 40, is decompressed to a predetermined low pressure by the first expansion valve 28, passes through the auxiliary heat exchanger 27, and flows into the first outdoor heat exchanger 26. Since the second refrigerant circuit 22 is not driven, heat exchange between the first refrigerant and the second refrigerant does not occur in the auxiliary heat exchanger 27. The first refrigerant that flows into the first outdoor heat exchanger 26 exchanges heat with the outdoor air and evaporates. The first refrigerant that has evaporated in the first outdoor heat exchanger 26 is sucked into the first compressor 24 through the four-way switching valve 25.

(Defrost operation)
The refrigeration system 10 is capable of a defrost operation for removing frost that has adhered to the first outdoor heat exchanger 26 during heating operation. The defrost operation can be performed, for example, by causing a high-temperature, high-pressure first refrigerant to flow into the first outdoor heat exchanger 26, similar to the above-described cooling operation.

(Refrigeration cycle of the first refrigerant circuit during cooling operation)
11 is a Mollier diagram for explaining the refrigeration cycle of the first refrigerant circuit during cooling operation, in which L indicates an isothermal line at an outside air temperature in summer, for example.
The first refrigerant used in the first refrigerant circuit 21 is carbon dioxide, and is pressurized by the first compressor 24 to a pressure exceeding the critical point P. Therefore, during cooling operation, the first outdoor heat exchanger 26 only releases heat from the first refrigerant to approximately the outside air temperature, and only the enthalpy difference Δh1 shown in FIG. 11 can be ensured. In this embodiment, by exchanging heat between the first refrigerant and a second refrigerant that is lower in temperature than the outside air temperature in the auxiliary heat exchanger 27, the first refrigerant can further release heat, and a further enthalpy difference Δh2 can be ensured. Therefore, the refrigeration capacity H of the refrigeration device 10 using the carbon dioxide refrigerant can be increased.

The refrigerant pipes 40 of the first refrigerant circuit 21 may be removed, for example, when the indoor unit 12 is replaced. At this time, the first refrigerant circuit 21 is opened, and there is a possibility of refrigerant leakage. Since the first refrigerant circuit 21 uses carbon dioxide as the first refrigerant, the adverse effects of leakage are small. In contrast, the second refrigerant circuit 22 circulates the second refrigerant only inside the outdoor unit 11, and is therefore rarely opened. In this embodiment, R290 (propane), which is flammable, is used as the second refrigerant, but since the second refrigerant circuit 22 is rarely opened, the possibility of leakage is low.

Fig. 2 is a plan view showing the inside of the outdoor unit of the refrigeration system. Fig. 3 is a view showing the inside of the outdoor unit as seen in the direction of the arrows B-B in Fig. 2. Fig. 4 is a view showing the inside of the outdoor unit as seen in the direction of the arrows C-C in Fig. 2. Fig. 5 is a view showing the inside of the outdoor unit as seen in the direction of the arrows D-D in Fig. 2.
The outdoor unit 11 includes a casing 55. The casing 55 is formed in a rectangular parallelepiped shape. As shown in Fig. 2, the inside of the casing 55 is divided into a machine chamber S1 and a heat exchange chamber S2 by a partition wall 56. Air intakes 55a1 and 55b1 are formed in two adjacent side walls 55a and 55b of the casing 55 arranged on the heat exchange chamber S2 side. An air outlet 55c1 is formed in the other side wall 55c adjacent to the one side wall 55b in which the air intake 55b1 is formed.

The machine chamber S1 of the casing 55 houses the first compressor 24, the second compressor 34, the first accumulator 32, the second accumulator 39, the auxiliary heat exchanger 27, etc. The heat exchange chamber S2 of the casing 55 houses the first outdoor heat exchanger 26, the second outdoor heat exchanger 36, the outdoor fan 41, etc. The outdoor fan 41 rotates around the rotation axis c. The outdoor fan 41 takes in air into the casing 55 from the air intakes 55a1 and 55b1, and discharges air to the outside of the casing 55 from the air outlet 55c1. The arrow a shown in Figures 2 and 3 indicates the direction of the air flow that is taken into the casing 55 from the air intakes 55a1 and 55b1 and passes through the first and second outdoor heat exchangers 26 and 36, and the arrow b indicates the direction of the air flow that is discharged to the outside of the casing 55 from the air outlet 55c1.

As shown in FIG. 2, the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are formed in a substantially L-shape when viewed from above. The first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are bent near the corner d between the two side walls 55a, 55b where the air intakes 55a1, 55b1 are formed, and are arranged along the two side walls 55a, 55b. When viewed from above, the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are formed in substantially the same shape and have substantially the same length.

As shown in Figures 3 to 5, the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are arranged side by side in the vertical direction. Specifically, the first outdoor heat exchanger 26 is arranged on the lower side, and the second outdoor heat exchanger 36 is arranged on the upper side. Air is supplied to both the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 by a common outdoor fan 41. The vertical height of the first outdoor heat exchanger 26 is greater than the vertical height of the second outdoor heat exchanger 36. Therefore, the air passing area in the first outdoor heat exchanger 26 is greater than the air passing area in the second outdoor heat exchanger 36.

FIG. 6 is an explanatory diagram that illustrates a schematic diagram of a first outdoor heat exchanger in the refrigeration apparatus.
The first outdoor heat exchanger 26 has a number of fins 26a and a heat transfer tube 26b. The number of fins 26a are formed in a rectangular plate shape in a side view and are arranged parallel to each other. The number of fins 26a is arranged so that the plate surfaces are aligned in the vertical direction.

The heat transfer tube 26b is a cylindrical tube with a circular cross section. The heat transfer tube 26b is made of a material mainly composed of copper. The heat transfer tube 26b is made of copper or a copper alloy. The heat transfer tube 26b has a plurality of straight tube sections 26b1 formed in a straight line and a curved tube section 26b2 formed in a U-shape. The straight tube section 26b1 extends in the direction in which the many fins 26a are arranged and penetrates the fins 26a. The curved tube section 26b2 is arranged at both ends of the first outdoor heat exchanger 26 in a top view and connects two adjacent straight tube sections 26b1 to each other. The multiple straight tube sections 26b1 are arranged in a staggered manner in the vertical direction and the air flow direction a as shown in FIG. 3. Tube plates 26c are provided at both ends of the first outdoor heat exchanger 26 in a top view. The shape of the first outdoor heat exchanger 26 is maintained by the tube plates 26c.

Fig. 7 is an explanatory diagram that shows a schematic of a second outdoor heat exchanger in the refrigeration device, and Fig. 8 is an enlarged cross-sectional view of the second outdoor heat exchanger.
The second outdoor heat exchanger 36 has a large number of fins 36a, a plurality of heat transfer tubes 36b, and headers 36c, 36d. The heat transfer tubes 36b are formed of a material mainly composed of aluminum. The heat transfer tubes 36b are made of aluminum or an aluminum alloy. The plurality of heat transfer tubes 36b are arranged in parallel to each other in the vertical direction. Each heat transfer tube 36b is arranged substantially horizontally.

The headers 36c and 36d are connected to one end and the other end of each heat transfer tube 36b in the longitudinal direction. The headers 36c and 36d include a liquid header 36c through which liquid refrigerant flows and a gas header 36d through which gas refrigerant flows. The headers 36c and 36d distribute the second refrigerant that flows in from outside the second outdoor heat exchanger 36 to each heat transfer tube 36b, and merge the second refrigerant that flows in from each heat transfer tube 36b and allow it to flow out to the outside of the second outdoor heat exchanger 36.

As shown in FIG. 8, the heat transfer tube 36b of this embodiment is a multi-hole tube having a plurality of refrigerant flow paths 36b1 inside. The plurality of refrigerant flow paths 36b1 are formed in a line along the air flow direction a. The cross-sectional shape of the heat transfer tube 36b cut in a direction perpendicular to the longitudinal direction is formed longitudinally in the air flow direction a, which is the direction in which the plurality of refrigerant flow paths 36b1 are arranged. In other words, the heat transfer tube 36b is a flat tube in which the length L2 in the air flow direction a (horizontal direction) is greater than the length (thickness) L1 in the vertical direction in the cross-section. Hereinafter, the heat transfer tube 36b of the second outdoor heat exchanger 36 is also referred to as a "flat multi-hole tube". The upper and lower surfaces of the flat multi-hole tube 36b are arranged approximately horizontally.

The vertical length L1 of the flat multi-hole tube 36b is set to, for example, 1 mm to 3 mm. The length L2 of the flat multi-hole tube 36b in the air flow direction a is set to, for example, 10 mm to 30 mm. In contrast, the outer diameter of the heat transfer tube 26b in the first outdoor heat exchanger 26 is set to, for example, 5 to 10 mm. Therefore, when viewed from the air flow direction a, the flat multi-hole tube 36b has a shorter vertical length than the heat transfer tube 26b, and has less resistance to the air flow.

The area of each refrigerant flow path 36b1 of the flat multi-hole tube 36b in the second outdoor heat exchanger 36 is smaller than the area of the refrigerant flow path of the heat transfer tube (cylindrical tube) 26b in the first outdoor heat exchanger 26. Therefore, in the second outdoor heat exchanger 36, the second refrigerant has more opportunities to come into contact with the flat multi-hole tube 36b, and can perform heat exchange more efficiently than the first outdoor heat exchanger 26. This makes it possible to reduce the amount of the second refrigerant used as much as possible. Since the second refrigerant in this embodiment is R290 (propane), which has flammability, it is extremely effective to reduce the amount of the second refrigerant in order to reduce the risk of leakage. For example, the amount of the second refrigerant used can be 1000g or less. Preferably, the amount of the second refrigerant used can be 150g or less.

The fins 36a of the second outdoor heat exchanger 36 are so-called corrugated fins. The fins 36a are arranged between the flat multi-hole tubes 36b adjacent in the vertical direction. The fins 36a are formed by bending a plate material into a wave shape. Therefore, the fins 36a extend in the longitudinal direction of the flat multi-hole tubes 36b while snaking up and down between the upper and lower flat multi-hole tubes 36b. The upper and lower ends of each fin 36a are respectively joined to the flat multi-hole tubes 36b by brazing.

FIG. 9 is an explanatory diagram that illustrates a schematic arrangement of the first outdoor heat exchanger and the second outdoor heat exchanger.
The first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are arranged next to each other in the vertical direction. A gap t is provided between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36. By providing such a gap t, it is possible to suppress heat transfer between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36. Note that a heat insulating material may be provided in the gap t. This makes it possible to further suppress heat transfer between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36.

The distance t between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 is set to 10 mm or less. This makes it possible to prevent the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 from becoming larger in the vertical direction as a whole. In addition, the larger the distance t between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36, the easier it is for air to pass through the distance t, and the flow rate of air passing through the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 decreases, resulting in a decrease in heat exchange efficiency. In this embodiment, the distance t is set to 10 mm or less, making it possible to prevent a decrease in the heat exchange efficiency of the first and second outdoor heat exchangers 26, 36.

On the other hand, the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are connected by connecting members 58 and 59. In a top view, the longitudinal end of the first outdoor heat exchanger 26 is disposed near the longitudinal end of the second outdoor heat exchanger 36. The connecting member of this embodiment includes a first connecting member 58 that connects the end of the first outdoor heat exchanger 26 and the end of the second outdoor heat exchanger 36 in a top view. The first connecting member 58 can be, for example, a member that connects the tube plate 26c of the first outdoor heat exchanger 26 and the headers 36c and 36d of the second outdoor heat exchanger 36. Alternatively, the first connecting member 58 can be configured by extending the tube plate 26c of the first outdoor heat exchanger 26 upward and connecting this tube plate 26c to the second outdoor heat exchanger 36.

The connecting member in this embodiment includes a second connecting member 59 that connects a mid-way portion of the first outdoor heat exchanger 26 in the longitudinal direction to a mid-way portion of the second outdoor heat exchanger 36 in a top view. In this embodiment, the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are connected by the second connecting member 59 at multiple points (e.g., two points) in the longitudinal direction.

Figure 10 is a cross-sectional view taken along line A-A in Figure 9. As shown in Figure 10, the second connecting member 59 has a generally H-shaped cross-sectional shape. The second connecting member 59 has a lower fitting portion 59a into which the upper end of the first outdoor heat exchanger 26 fits, and an upper fitting portion 59b into which the lower end of the second outdoor heat exchanger 36 fits. By providing the second connecting member 59, it is possible to suppress misalignment in the horizontal direction (air flow direction a) or the up-down direction between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36.

In the present embodiment, the refrigeration device 10 operates only the first refrigerant circuit 21 during heating operation, and stops the second refrigerant circuit 22. Therefore, the second outdoor heat exchanger 36 is cooled by heat transfer from the first outdoor heat exchanger 26 via the connecting members 58, 59. If the second outdoor heat exchanger 36 were arranged below the first outdoor heat exchanger 26, water generated in the first outdoor heat exchanger 26 would drip onto the second outdoor heat exchanger 36, and the water would accumulate on the flat multi-hole tubes 36b of the second outdoor heat exchanger 36, which could cause freezing. In the present embodiment, the second outdoor heat exchanger 36 is arranged above the first outdoor heat exchanger 26, so that such problems can be prevented from occurring.

[Second embodiment]
FIG. 12 is a side view showing the inside of the outdoor unit in the refrigeration apparatus according to the second embodiment of the present disclosure.
In this embodiment, the positional relationship between the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 in the outdoor unit 11 and the outdoor fan 41 is different from that in the first embodiment. In the outdoor unit 11 of this embodiment, the outdoor fan 41 is provided on the upper part of the casing 55, and the outdoor fan 41 blows air upward. Therefore, in the outdoor unit 11, an air intake 55d is formed on the side of the casing 55, and an air outlet 55e is provided on the upper surface of the casing 55. The first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 are arranged to face three or four side surfaces of the casing 55, and are arranged so that the air taken in from the intake 55d passes through them as shown by the arrow a. The air that has passed through the first outdoor heat exchanger 26 and the second outdoor heat exchanger 36 is discharged upward from the outlet 55e of the casing 55 as shown by the arrow b.

In this embodiment, the outdoor fan 41 is disposed at the top of the casing 55, in other words, at the top of the second outdoor heat exchanger 36. Therefore, the second outdoor heat exchanger 36 is closer to the outdoor fan 41 than the first outdoor heat exchanger 26, and the flow rate of the air passing through the second outdoor heat exchanger 36 is higher than the flow rate of the air passing through the first outdoor heat exchanger 26. Therefore, even if water gets on the second outdoor heat exchanger 36 and accumulates on the flat multi-hole tubes 36b or inside the corrugated fins 36a, the water can be easily discharged by the air flow passing through the second outdoor heat exchanger 36.

[Effects of the embodiment]
(1) The refrigeration device 10 of this embodiment includes a first refrigerant circuit 21 that circulates a first refrigerant, a second refrigerant circuit 22 that circulates a second refrigerant different from the first refrigerant, and a third heat exchanger (auxiliary heat exchanger) 27 that exchanges heat between the first refrigerant and the second refrigerant. The first refrigerant circuit 21 includes a first heat exchanger (first outdoor heat exchanger) 26 having a circular tubular heat transfer tube 26b, and the second refrigerant circuit 22 includes a second heat exchanger (second outdoor heat exchanger) 36 having a flat multi-hole tube 36b. The first heat exchanger 26 and the second heat exchanger 36 are arranged vertically, and the second heat exchanger 36 is arranged above the first heat exchanger 26.

According to the above configuration, for example, when the heating operation is performed when the outside air temperature is low, such as in winter, and the first heat exchanger 26 is used as an evaporator, frost may adhere to the first heat exchanger 26. When the frost melts due to defrost operation or the like, water droplets may fall downward from the first heat exchanger 26. On the other hand, the flat multi-hole tube 36b of the second heat exchanger 36 has a length L2 in the air flow direction a (horizontal direction) in the cross section that is greater than the length L1 in the vertical direction, so that water is likely to accumulate (remain) on its upper surface. In the refrigeration device 10 of this embodiment, the second heat exchanger 36 is disposed above the first heat exchanger 26, so that water dripping from the first heat exchanger 26 does not fall on the flat multi-hole tube 36b of the second heat exchanger 36. Therefore, it is possible to suppress water from accumulating or freezing on the flat multi-hole tube 36b. Even if water is generated in the second heat exchanger 36 and drips onto the first heat exchanger 26, the water is less likely to accumulate on the circular heat transfer tube 26b, so the water can be prevented from freezing.

(2) In this embodiment, the second heat exchanger 36 includes a plurality of flat multi-hole tubes 36b spaced apart in the vertical direction, and serpentine fins 36a arranged between adjacent flat multi-hole tubes 36b in the vertical direction.
In the second heat exchanger 36 having the corrugated fins 36a between the flat multi-hole tubes 36b adjacent to each other above and below, if water gets into the corrugated fins 36a, it is difficult to drain, and the accumulated water may freeze and damage the brazed parts (bonded parts) between the corrugated fins 36a and the flat multi-hole tubes 36b. In the refrigeration device 10 of this embodiment, the second heat exchanger 36 is disposed above the first heat exchanger 26, and water generated in the first heat exchanger 26 does not drip onto the second heat exchanger 36, so that the possibility of water getting into the corrugated fins 36a is reduced, and freezing of the water can be suppressed.

(3) In the refrigeration device 10 of this embodiment, the vertical distance t between the first heat exchanger 26 and the second heat exchanger 36 is 10 mm or less.
In the refrigeration device 10 of this embodiment, the second heat exchanger 36 is disposed above the first heat exchanger 26, and water generated in the first heat exchanger 26 does not drip onto the second heat exchanger 36 and freeze on the flat multi-hole tube 36b, so that the interval t between the first heat exchanger 26 and the second heat exchanger 36 can be made small to 10 mm or less, and the size of the first and second heat exchangers as a whole (particularly the vertical dimension) can be suppressed. In addition, if the interval between the first heat exchanger 26 and the second heat exchanger 36 is large, the air flow can easily pass through the interval t, and the heat exchange efficiency of the first heat exchanger 26 and the second heat exchanger 36 may decrease, but by making the interval t 10 mm or less, the air flow passing through is reduced, and the first and second heat exchangers 26, 36 can efficiently exchange heat.

(4) In the refrigeration device of the above embodiment, the heat transfer tube 26b is made of a material mainly composed of copper, and the flat multi-hole tube 36b is made of a material mainly composed of aluminum.

Copper has a higher electric potential than aluminum, so if water generated in copper comes into contact with aluminum, there is a possibility that electrolytic corrosion will occur in the aluminum. In this embodiment, the flat multi-hole tube 36b of the second heat exchanger 36 located on the upper side is made of a material mainly composed of aluminum, and the heat transfer tube 26b of the first heat exchanger 26 located on the lower side is made of a material mainly composed of copper, so that water generated in the first heat exchanger 26 does not drip onto the second heat exchanger 36, and electrolytic corrosion of the flat multi-hole tube 36b can be suppressed.

(5) In the second embodiment described above, the refrigeration device 10 further includes a casing 55 that houses the first heat exchanger 26 and the second heat exchanger 36, and a fan (outdoor fan) 41 that is disposed above the second heat exchanger 36 and generates an air flow that passes through the first heat exchanger 26 and the second heat exchanger 36.

With this configuration, by operating the fan 41, the flow rate of the air passing through the second heat exchanger 36 located above can be increased compared to the flow rate of the air passing through the first heat exchanger 26 located below. Therefore, even if rainwater or the like adheres to the second heat exchanger 36, the water droplets can be easily discharged by the high flow rate air flow. Therefore, freezing of water on the flat multi-hole pipe 36b can be suppressed.

(6) The refrigeration device 10 of the above embodiment further includes connecting members 58, 59 that connect the first heat exchanger 26 and the second heat exchanger 36.

When the first heat exchanger 26 and the second heat exchanger 36 are connected by the connecting members 58, 59, the heat of the first heat exchanger 26 may be transferred to the second heat exchanger 36 through the connecting members 58, 59. Therefore, when the heating operation is performed in winter or other times when the outside air temperature is low and the first heat exchanger 26 is used as an evaporator, the heat of the first heat exchanger 26 is transferred to the second heat exchanger 36 through the connecting members 58, 59, and the second heat exchanger 36 is cooled. Since the water generated in the first heat exchanger 26 does not drip onto the second heat exchanger 36, the accumulation of water on the flat multi-hole tube 36b is suppressed. Therefore, even if the second heat exchanger 36 is cooled, the water can be suppressed from freezing on the flat multi-hole tube 36b.

(7) In the above embodiment of the refrigeration device 10, the longitudinal end of the first heat exchanger 26 is positioned near the longitudinal end of the second heat exchanger 36 when viewed from above, and therefore the connecting member can include a first connecting member 58 that connects the end of the first heat exchanger 26 and the end of the second heat exchanger 36.

(8) In the above embodiment, the connecting member of the refrigeration device 10 includes a second connecting member 59 that connects the middle portions of the first heat exchanger 26 and the second heat exchanger 36 in the longitudinal direction when viewed from above.

With this configuration, even if vibrations caused by transportation or the like are transmitted to the refrigeration device 10, the mid-length portion of the first heat exchanger 26 and the mid-length portion of the second heat exchanger 36 are less likely to vibrate in different directions, preventing the two from rubbing against each other or colliding with each other.

Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims.

For example, in the above embodiment, R290 (propane) is exemplified as the second refrigerant used in the second refrigerant circuit 22, but is not limited thereto. As the second refrigerant, it is possible to use a refrigerant having combustibility and toxicity, or a refrigerant having a relatively high GWP (global warming potential) (for example, a refrigerant having a GWP of 4 or more and 675 or less, which is higher than that of natural refrigerants). As the refrigerant having combustibility, in addition to the above-mentioned R290 (propane), R32, R1234yf, R474a, R600a (isobutane), etc. can be used. As the refrigerant having toxicity, NH ₃ (ammonia), etc. can be used. As the refrigerant having a high GWP, R32, R454B, R454C, etc. can be used. Of these, the GWP of R32 is the maximum of 675.

The second outdoor heat exchanger 36 may have rectangular flat fins similar to the fins 26a of the first outdoor heat exchanger 26, instead of the corrugated fins 36a. In this case, a large number of fins can be arranged in a vertical direction, and the flat multi-hole tube 36b can pass through the multiple fins.

10: Refrigeration device 21: First refrigerant circuit 22: Second refrigerant circuit 26: First outdoor heat exchanger (first heat exchanger)
27: Auxiliary heat exchanger (third heat exchanger)
36: Second outdoor heat exchanger (second heat exchanger)
36a: Corrugated fin 36b: Flat multi-hole tube 41: Outdoor fan 55: Casing 58: First connecting member 59: Second connecting member

Claims (8)

a first refrigerant circuit (21) for circulating a first refrigerant;
a second refrigerant circuit (22) for circulating a second refrigerant different from the first refrigerant;
a third heat exchanger (27) for exchanging heat between the first refrigerant and the second refrigerant;
A fan (41) for generating an air flow,
The first refrigerant circuit (21) includes a first heat exchanger (26) having a circular heat transfer tube (26b),
The second refrigerant circuit (22) includes a second heat exchanger (36) having flat multi-hole tubes (36b),
The first heat exchanger (26) and the second heat exchanger (36) are arranged vertically side by side,
The second heat exchanger (36) is disposed above the first heat exchanger (26) ;
A refrigeration device, wherein the fan (41) generates an air flow that passes through the first heat exchanger (26) and the second heat exchanger (36) in a direction intersecting a vertical direction in which the first heat exchanger (26) and the second heat exchanger (36) are arranged . The refrigeration device according to claim 1, wherein the second heat exchanger (36) comprises a plurality of the flat multi-hole tubes (36b) arranged at intervals in the vertical direction, and serpentine fins arranged between adjacent flat multi-hole tubes (36b) in the vertical direction. The refrigeration system according to claim 1 or 2, wherein the vertical distance between the first heat exchanger (26) and the second heat exchanger (36) is 10 mm or less. The refrigeration device according to claim 1 or 2, wherein the heat transfer tube (26b) is made of a material mainly composed of copper, and the flat multi-hole tube (36b) is made of a material mainly composed of aluminum. a casing (55) that houses the first heat exchanger (26) and the second heat exchanger (36);
3. The refrigeration apparatus according to claim 1, further comprising: a fan (41) disposed above the second heat exchanger (36) and configured to generate an airflow passing through the first heat exchanger (26) and the second heat exchanger (36). The refrigeration device according to claim 1 or 2, further comprising a connecting member (58, 59) that connects the first heat exchanger (26) and the second heat exchanger (36). When viewed from above, a longitudinal end of the first heat exchanger (26) is disposed in the vicinity of a longitudinal end of the second heat exchanger (36),
7. The refrigeration system of claim 6, wherein the connecting members include a first connecting member (58) connecting the end of the first heat exchanger (26) and the end of the second heat exchanger (36). The refrigeration apparatus according to claim 6, wherein the connecting member includes a second connecting member (59) that connects longitudinal mid-portions of the first heat exchanger (26) and the second heat exchanger (36) to each other when viewed from above.

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