Refrigerant circulation pipe and freezer

Abstract

To provide a refrigerant circulation pipe that can easily make a refrigerant flowing into a plate-type water-refrigerant heat exchanger into a state where liquid and gas phases are mixed, and a heat exchanger.SOLUTION: A refrigerant circulation pipe is connected to a plate-type water-refrigerant heat exchanger, and is provided between a plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe comprising a plurality of straight parts extending linearly, and a plurality of curved parts connecting the ends of the straight parts, where a bending angle of each curved part is an obtuse angle or a right angle.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a refrigerant circulation pipe and a refrigeration device. [Background technology]

[0002] Patent Document 1 discloses a refrigerant supply device that uniformly supplies a gas-liquid two-phase refrigerant to each evaporation tube of a dry evaporator. This refrigerant supply device includes a refrigerant distribution device connected to an expansion valve and a pressure reducing device that connects the refrigerant distribution device to the dry evaporator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 61-062756 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a refrigerant circulation pipe and a heat exchanger that can easily make the refrigerant flowing into a plate-type water-refrigerant heat exchanger into a mixed state of liquid and gas phases. [Means for solving the problem]

[0005] The refrigerant circulation piping in the present disclosure is connected to a plate-type water-refrigerant heat exchanger and provided between the plate-type water-refrigerant heat exchanger and an expansion valve, and includes a plurality of straight sections extending linearly and a plurality of curved sections connecting the ends of the straight sections, and the bending angle of each of the curved sections is an obtuse angle or a right angle.

[0006] The refrigeration device according to the present disclosure includes an expansion valve, a plate-type water-refrigerant heat exchanger, and a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, wherein the refrigerant circulation pipe includes a plurality of straight sections extending linearly and a plurality of curved sections connecting ends of the straight sections, and the bending angle of each of the curved sections is an obtuse angle or a right angle. [Effects of the Invention]

[0007] The refrigerant circulation pipe and the refrigeration system according to the present disclosure allow the gas-liquid two-phase refrigerant that has flowed into the refrigerant circulation pipe from the expansion valve to flow into the plate-type water-refrigerant heat exchanger while suppressing the effects of centrifugal force, thereby making it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger to be in a mixed state of liquid and gas phases. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a refrigeration circuit of a refrigeration device according to a first embodiment. [Figure 2] A perspective view showing the inside of a refrigeration device [Figure 3] Enlarged view of Figure 2 [Figure 4] A side view showing the inside of the refrigeration device [Figure 5] Perspective view of refrigerant circulation piping [Figure 6] Front view of refrigerant circulation piping [Figure 7] Side view of refrigerant circulation piping [Figure 8] Top view of refrigerant circulation piping [Figure 9] IX-IX cross section of FIG. 7 [Figure 10] XX cross-sectional view of FIG. 8 [Figure 11] 1 is a table showing various parameters of the refrigeration device 1 during the experiment in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Findings that formed the basis of this disclosure) At the time the inventors arrived at the idea of ​​the present disclosure, in devices using a refrigeration cycle, it was common for the refrigerant to be converted into a gas-liquid two-phase state after passing through an expansion valve before flowing into an evaporator. Therefore, in order to improve the efficiency of heat exchange in the evaporator, a technology was proposed in the industry in which the refrigerant distributed by a refrigerant distribution device was decompressed and flowed into the evaporator in parallel in order to evenly distribute the gas and liquid phases to each section of the evaporator. Under these circumstances, the inventors discovered a problem in that, even if a plate-type water-refrigerant heat exchanger has multiple channels, it often has only one refrigerant inlet and outlet, and in order to evenly distribute the gas and liquid phases, it is necessary to introduce a refrigerant in a gas-liquid mixed state. The subject matter of the present disclosure was designed to solve this problem. The present disclosure provides a refrigerant circulation pipe and a heat exchanger that can easily make the refrigerant flowing into a plate-type water-refrigerant heat exchanger into a mixed state of liquid and gas phases.

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0011] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to the drawings. [1-1.Configuration] [1-1-1. Refrigeration circuit configuration] FIG. 1 is a diagram showing a refrigeration circuit of a refrigeration system 1 according to a first embodiment. In this embodiment, the refrigeration system 1 is an outdoor unit of a heat pump type hot water heater. The hot water heater is a device that heats a room by flowing water heated by the refrigeration cycle of the refrigeration system 1 through a heat exchanger of an indoor unit. The hot water heater of this embodiment can also perform cooling operation by flowing water cooled by the refrigeration cycle of the refrigeration system 1 through the indoor unit. In FIG. 1, arrows indicate the flow of refrigerant and water during cooling operation of the hot water heater.

[0012] The refrigeration system 1 is provided with a compressor 2. The compressor 2 is a device that draws in, compresses, and discharges a refrigerant. In the refrigeration system 1, a flow path switching mechanism 3 is connected to the discharge side and suction side of the compressor 2. The flow path switching mechanism 3 switches the destination of the refrigerant discharged to the compressor 2 between an air heat exchanger 4 and a plate-type water-refrigerant heat exchanger 10, and causes the destination heat exchangers 4, 10 to function as condensers. The flow path switching mechanism 3 also draws the refrigerant that has passed through the evaporator of the heat exchangers 4, 10 into the compressor 2. The flow path switching mechanism 3 is, for example, a four-way valve.

[0013] The air heat exchanger 4 is a heat exchanger that exchanges heat between the refrigerant inside and outside air. The air heat exchanger 4 is, for example, a fin-tube type heat exchanger. The refrigeration system 1 is provided with a blower 5 that blows outside air through the air heat exchanger 4. In this embodiment, the blower 5 is an axial fan.

[0014] The plate-type water-refrigerant heat exchanger 10 is a plate-type heat exchanger that exchanges heat between the refrigerant flowing inside and water. The water heated or cooled by the plate-type water-refrigerant heat exchanger 10 circulates between the refrigeration device 1 and the indoor unit to air-condition the room.

[0015] The air heat exchanger 4 and the plate-type water-refrigerant heat exchanger 10 are connected via an expansion valve 6. A receiver tank 46 that stores low-temperature, high-pressure liquid-phase refrigerant cooled by the condenser is provided between the plate-type water-refrigerant heat exchanger 10 and the expansion valve 6 (see FIG. 2). The expansion valve 6 is a valve that reduces the pressure of the refrigerant flowing from the condenser of each heat exchanger 4, 10 via the receiver tank 46 to produce a two-phase gas-liquid refrigerant, and allows the refrigerant to flow into the evaporator of each heat exchanger 4, 10. In this embodiment, the opening of the expansion valve 6 can be adjusted by electronic control, and the flow rate of the refrigerant is adjusted by changing the opening.

[0016] [1-1-2. Arrangement of components in refrigeration equipment] Fig. 2 is a perspective view showing the inside of the refrigeration device 1. In the figure, the symbol X indicates the left side of the refrigeration device 1, the symbol Y indicates the front side of the refrigeration device 1, and the symbol Z indicates the upper side. As shown in Fig. 2, inside the refrigeration device 1, there are formed a blower chamber 7, which is a space partitioned on the left side by a partition plate 9, and a machine chamber 8, which is a space partitioned on the right side of the partition plate 9. The partition plate 9 is made of sheet metal and is installed in an orientation that is approximately perpendicular to the left-right direction.

[0017] An air heat exchanger 4 and a blower 5 are provided in the blower chamber 7. The air heat exchanger 4 is provided on the right side and rear side of the blower chamber 7. The blower 5 blows air inside the refrigeration apparatus 1 forward, thereby drawing in outside air through the air heat exchanger 4 and exchanging heat between the outside air and the refrigerant inside the air heat exchanger 4. In this embodiment, a refrigeration apparatus 1 in which two blowers 5 are provided vertically in the blower chamber 7 will be described as an example, but the number of blowers 5 in the refrigeration apparatus 1 is not particularly limited.

[0018] The machine room 8 is provided with a compressor 2, a flow path switching mechanism 3, an expansion valve 6, a receiver tank 46, and a plate-type water-refrigerant heat exchanger 10. The compressor 2 is placed on the bottom plate 1a of the refrigeration device 1 via rubber legs. The flow path switching mechanism 3 is located above the compressor 2. The plate-type water-refrigerant heat exchanger 10 is provided at a position spaced above the bottom plate 1a via a support member 8a made of sheet metal.

[0019] FIG. 3 is an enlarged view of FIG. 2. FIG. 4 is a side view showing the internal configuration of the refrigeration apparatus 1, showing the interior of the refrigeration apparatus 1 as seen from the right side. As shown in FIGS. 3 and 4, the plate-type water-refrigerant heat exchanger 10 is provided with a first refrigerant-side connection port 11 and a second refrigerant-side connection port 12. Each refrigerant-side connection port 11, 12 is an opening that communicates with a flow path in the plate-type water-refrigerant heat exchanger 10 through which the refrigerant flows. The first refrigerant-side connection port 11 is formed at the lower end of the front side of the right side of the plate-type water-refrigerant heat exchanger 10. The second refrigerant-side connection port 12 is formed above the first refrigerant-side connection port 11 on the right side of the plate-type water-refrigerant heat exchanger 10.

[0020] A refrigerant circulation pipe 30 is connected to the first refrigerant side connection port 11. The refrigerant circulation pipe 30 is a refrigerant pipe provided between the first refrigerant side connection port 11 and the expansion valve 6. More specifically, the refrigerant circulation pipe 30 is connected to the first refrigerant side connection port 11 and a pipe 47. The pipe 47 is connected to the receiver tank 46. A gas side pipe 13 is connected to the second refrigerant side connection port 12. The gas side pipe 13 is a refrigerant pipe that extends from the second refrigerant side connection port 12 and is connected to the flow path switching mechanism 3. The gas side pipe 13 mainly carries gas refrigerant, which has a large specific volume, and therefore has a larger diameter than the refrigerant circulation pipe 30, through which liquid refrigerant or refrigerant in a gas-liquid two-phase state flows.

[0021] The plate-type water-refrigerant heat exchanger 10 is also provided with a first water-side connection port 14 and a second water-side connection port 15. Each water-side connection port 14, 15 is an opening that communicates with a flow path through which water flows in the plate-type water-refrigerant heat exchanger 10. The first water-side connection port 14 is provided at the lower end of the rear side of the right side of the plate-type water-refrigerant heat exchanger 10. The second water-side connection port 15 is provided above the first water-side connection port 14 on the right side of the plate-type water-refrigerant heat exchanger 10.

[0022] The first water-side connection port 14 is connected to the discharge side of a circulation pump 16 that circulates water. A valve 16a is provided on the suction side of the circulation pump 16, which protrudes rearward to the outside of the refrigeration device 1 and can be connected to a water pipe outside the refrigeration device 1.

[0023] A gas-liquid separator 17 that removes gas from the water flowing out of the plate-type water-refrigerant heat exchanger 10 is provided at the second water-side connection port 15. A valve 18a that can be connected to a water pipe outside the refrigeration device 1 via an outlet-side water pipe 18 is provided at the outlet side of the gas-liquid separator 17. In addition, a flow rate sensor 19 that measures the flow rate of water is provided at the outlet-side water pipe 18.

[0024] [1-1-3. Configuration of refrigerant circulation piping] Fig. 5 is a perspective view of the refrigerant circulation pipe 30. As shown in Fig. 5, the refrigerant circulation pipe 30 is formed with five straight portions 31 to 35 that extend linearly and four curved portions 36 to 39 that connect adjacent straight portions 31 to 35.

[0025] Fig. 6 is a front view of the refrigerant circulation piping 30, showing the refrigerant circulation piping 30 as seen from the front. Fig. 7 is a side view of the refrigerant circulation piping 30, showing the refrigerant circulation piping 30 as seen from the right. Fig. 8 is a top view of the refrigerant circulation piping 30, showing the refrigerant circulation piping 30 as seen from above.

[0026] A first straight portion 31 parallel to the left-right direction is formed at the lower end of the refrigerant circulation pipe 30. That is, the first straight portion 31 extends horizontally. The left end of the first straight portion 31 is connected to the first refrigerant side connection port 11.

[0027] The right end of the first straight portion 31 is connected to the first curved portion 36. The first curved portion 36 is a portion of the refrigerant circulation piping 30 that curves upward from the right end of the first straight portion 31. The upper end of the first curved portion 36 is connected to the lower end of the second straight portion 32. The second straight portion 32 is a portion of the refrigerant circulation piping 30 that extends linearly in the up-down direction. Specifically, in this embodiment, the second straight portion 32 extends linearly and parallel to the vertical direction. Also, as shown in FIG. 6, the length L2 of the second straight portion 32 is longer than the length L1 of the first straight portion 31.

[0028] 6 and 7, the bending angle A1 of the first curved portion 36 is a right angle. In other words, the bending angle A1 is the angle between the first straight portion 31 and the second straight portion 32. Hereinafter, in this specification, the bending angles A1 to A4 of the curved portions 36 to 39 refer to the angles between the two straight portions 31 to 35 connecting to both ends of each of the curved portions 36 to 39. In other words, when the bending angles A1 to A4 of each of the curved portions 36 to 39 are large, each of the curved portions 36 to 39 becomes closer to a straight line, compared to when the bending angles of the curved portions 36 to 39 are small.

[0029] The upper end of the second straight portion 32 is connected to the lower end of the second curved portion 37. The second curved portion 37 is a portion of the refrigerant circulation piping 30 that curves from the upper end of the second straight portion 32 toward the front left. The bending angle A2 of the second curved portion 37 is a right angle.

[0030] The left front end of the second curved portion 37 is connected to the third straight portion 33. The third straight portion 33 is a portion of the refrigerant circulation piping 30 that extends linearly toward the left front from the left front end of the second curved portion 37. In detail, the third straight portion 33 extends horizontally toward the left front.

[0031] The left front end of the third straight section 33 is connected to the right rear end of the third curved section 38. The third curved section 38 is a portion of the refrigerant circulation piping 30 that curves obliquely upward and left front from the left front end of the third straight section 33. As shown in Figures 6 to 8, the bending angle A3 of the third curved section 38 is an obtuse angle.

[0032] The upper end of the third curved portion 38 is connected to the lower end of the fourth straight portion 34. The fourth straight portion 34 is a portion of the refrigerant circulation piping 30 that extends linearly from the upper end of the third curved portion 38 in a direction in which the left front side is positioned upward.

[0033] The upper end of the fourth straight portion 34 is connected to the lower end of the fourth curved portion 39. The fourth curved portion 39 is a portion of the refrigerant circulation piping 30 that curves leftward from the upper end of the fourth straight portion 34. As shown in Figures 6 to 8, the bending angle A4 of the fourth curved portion 39 is an obtuse angle.

[0034] The left end of the fourth curved portion 39 is connected to the right end of the fifth straight portion 35. The fifth straight portion 35 is a portion of the refrigerant circulation piping 30 that extends linearly leftward from the left end of the fourth curved portion 39. More specifically, the fifth straight portion 35 extends horizontally leftward. The left end of the fifth straight portion 35 is connected to the right end of the piping 47. As described above, the piping 47 is connected to the receiver tank 46, and therefore the fifth straight portion 35 is connected to the expansion valve 6 via the piping 47 and the receiver tank 46. Note that the fifth straight portion 35 has a protrusion 35a that protrudes radially outward for positioning relative to the piping 47.

[0035] In this embodiment, the refrigerant circulation piping 30 is specifically configured by brazing a first piping member 41, a second piping member 43, and a connecting piping 45 together. The first piping member 41 is a hollow member with a circular cross-section that constitutes substantially the entire first straight section 31, the entire first curved section 36, and substantially the entire second straight section 32 except for the upper end portion thereof. The second piping member 43 is a hollow member with a circular cross-section that constitutes the upper end portion of the second straight section 32, the second curved section 37, the third straight section 33, the third curved section 38, the fourth straight section 34, the fourth curved section 39, and the fifth straight section 35 thereof. The connecting piping 45 is a hollow member with a circular cross-section that is provided on the first straight section 31 and extends laterally.

[0036] 9 is a cross-sectional view showing the IX-IX cross section of FIG. 7, illustrating the brazed portion between the first piping member 41 and the second piping member 43, cut along a cross section perpendicular to the front-rear direction. As shown in FIG. 9, the upper end of the first piping member 41 is brazed to the second piping member 43 while being inserted into the lower end of the second piping member 43. Therefore, the outer diameter D2 of the first piping member 41 is equal to or smaller than the inner diameter D3 of the second piping member 43, and the inner diameter D1 of the first piping member 41 is smaller than the inner diameter D3 of the second piping member 43. That is, in the refrigerant circulation piping 30, the inner diameter D1 of the first piping member 41 on the side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 of the second piping member 43 on the side closer to the expansion valve 6 (the side closer to the receiver tank 46). Also, as shown in FIG. 9, the first piping member 41 has a protrusion 42a protruding radially outward. The protrusion 42a contacts the end face of the second piping member 43 to position the first piping member 41 and the second piping member 43 together.

[0037] FIG. 10 is a cross-sectional view showing the XX section of FIG. 8 , illustrating the brazed portion between the first piping member 41 and the connecting pipe 45, taken along a cross section perpendicular to the front-to-rear direction. As shown in FIG. 10 , the connecting pipe 45 is brazed to the first piping member 41 while being placed over the first piping member 41 from the outside. Therefore, the outer diameter D2 of the first piping member 41 is equal to or smaller than the inner diameter D5 of the connecting pipe 45, and the inner diameter D1 of the first piping member 41 is smaller than the inner diameter D5 of the connecting pipe 45. Also, as shown in FIG. 10 , the first piping member 41 has a protrusion 42b that protrudes radially outward. The protrusion 42b contacts the end face of the connecting pipe 45 to position the first piping member 41 and the connecting pipe 45. The inner diameter D5 and outer diameter D6 of the connecting pipe 45 are sized to allow connection to the first refrigerant-side connection port 11 of the plate-type water-refrigerant heat exchanger 10. In this embodiment, the inner diameter D5 and the outer diameter D6 of the connecting pipe 45 are substantially equal to the inner diameter D3 and the outer diameter D4 of the second pipe member 43.

[0038] The left end of the first piping member 41 extends to the left side to a position that substantially coincides with the left end of the connecting pipe 45. Therefore, the inner diameter of substantially the entire range of the first straight portion 31 coincides with the inner diameter D1 of the first piping member 41.

[0039] The inventors conducted an experiment to verify the suitable inner diameter D1 and outer diameter D2 for the refrigerant circulation rate in the refrigeration circuit of the refrigeration device 1, i.e., the refrigerant circulation rate passing through the interior of the refrigerant circulation pipe 30. As a result, the inventors discovered that when the refrigerant circulation rate passing through the interior is 2.27 kg / min or less, the outer diameter D2 is preferably 7.94 mm or less. The inventors also discovered that the suitable range of the outer diameter D2 is 3.50 mm or less per 1.0 kg / min of the refrigerant circulation rate passing through the interior of the refrigerant circulation pipe 30. The relationship between the refrigerant circulation rate and the inner diameter D1 and outer diameter D2 will be explained in the examples described later.

[0040] In this embodiment, the refrigeration system 1 can be operated in an energy saving mode. The energy saving mode is an operation mode in which the compressor 2 is driven at a capacity lower than full capacity in order to save energy in the refrigeration system 1. In the energy saving mode, the amount of refrigerant circulating through the refrigerant circulation pipe 30 is less than in an operation mode in which the full capacity of the compressor 2 is used. In this embodiment, during cooling operation in the energy saving mode of the refrigeration system 1, the refrigerant circulation rate is 2.27 kg / min, the outer diameter D2 is 7.94 mm, and the outer diameter D2 per refrigerant circulation rate of 1.0 kg / min is 3.50 mm.

[0041] [1-2. Operation] The operation of the refrigeration system 1 configured as above during cooling operation will be described below.

[0042] 1, during cooling operation, the flow path switching mechanism 3 causes the refrigerant discharged from the compressor 2 to flow through the air heat exchanger 4 to dissipate heat. The refrigerant that has dissipated heat in the air heat exchanger 4 is liquefied, passes through the expansion valve 6, and becomes a two-phase gas-liquid refrigerant. The refrigerant then passes through the receiver tank 46 and the pipe 47 and flows into the refrigerant circulation pipe 30.

[0043] The refrigerant in a gas-liquid two-phase state that flows into the refrigerant circulation pipe 30 passes through the fifth straight section 35, the fourth curved section 39, the fourth straight section 34, the third curved section 38, the third straight section 33, the second curved section 37, the second straight section 32, the first curved section 36, and the first straight section 31, in that order. The refrigerant that has passed through the first straight section 31 flows into the plate-type water-refrigerant heat exchanger 10 via the first refrigerant-side connection port 11.

[0044] At this time, when the refrigerant in a gas-liquid two-phase state passes through each of the curved portions 36 to 39, a centrifugal force is applied to the refrigerant according to the bending angles A1 to A4 and the curvature radius of the curved portions 36 to 39. Normally, when centrifugal force is applied to the refrigerant in a gas-liquid two-phase state, the liquid refrigerant, which has a higher specific gravity, tends to flow more toward the outside of the curve than the gas refrigerant, which has a lower specific gravity, and the gas and liquid phases are more likely to separate.

[0045] In contrast, in the present embodiment, the bending angles A1 to A4 of the curved portions 36 to 39 are configured to be obtuse angles or right angles. Therefore, compared to the case where the bending angles A1 to A4 of the curved portions 36 to 39 include acute angles, in the present embodiment, the centrifugal force acting on the refrigerant flowing through the curved portions 36 to 39 can be reduced, making it difficult for the refrigerant to separate into gas and liquid phases.

[0046] In this embodiment, the second straight section 32, which is the straight section immediately preceding the first straight section 31 connected to the plate-type water-refrigerant heat exchanger 10, extends upward from the first curved section 36 connecting the first straight section 31 and the second straight section 32. Therefore, in the second straight section 32, the refrigerant flow direction and the direction of gravity acting on the refrigerant are aligned downward, making it easier to maintain or promote mixing of the gas and liquid phases of the refrigerant. In this embodiment, the second straight section 32 is parallel to the vertical direction, making it easier to maintain or promote mixing of the gas and liquid phases in particular. Furthermore, the length L2 of the second straight section 32 is longer than the length L1 of the first straight section 31. Therefore, while maintaining or promoting mixing of the gas and liquid phases in the second straight section 32, the gas and liquid phases are less likely to separate when passing through the first straight section 31.

[0047] In the refrigerant circulation piping 30, the inner diameter D1 of the first piping member 41 closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 of the second piping member 43 closer to the expansion valve 6. In the refrigerant circulation piping 30, the connecting piping 45 connected to the first refrigerant-side connection port 11 of the plate-type water-refrigerant heat exchanger 10 is fitted over the outside of the first piping member 41, so the inner diameter of most of the first straight section 31 is the inner diameter D1. Furthermore, the outer diameter D2 is 3.50 mm or less per 1.0 kg / min refrigerant circulation rate. This makes it easy to increase the flow rate of the refrigerant passing through the first piping member 41 just before flowing into the plate-type water-refrigerant heat exchanger 10 and to easily suppress separation of the refrigerant into gas and liquid phases due to gravity or other factors.

[0048] The refrigerant in a gas-liquid two-phase state that flows into the plate-type water-refrigerant heat exchanger 10 absorbs heat from the water flowing through the plate-type water-refrigerant heat exchanger 10, evaporates, and turns into gas refrigerant, which returns to the compressor 2. In this embodiment, the mixture of gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 is easily maintained, so the gas and liquid phases tend to flow uniformly within the plate-type water-refrigerant heat exchanger 10, making it easy to cool water efficiently. The refrigeration system 1 cools the room by driving the circulation pump 16 to circulate water between the indoor unit and the plate-type water-refrigerant heat exchanger 10 while cooling it.

[0049] [1-3. Effects, etc.] As described above, in this embodiment, the refrigerant circulation pipe 30 is connected to the plate-type water-refrigerant heat exchanger 10 and is provided between the plate-type water-refrigerant heat exchanger 10 and the expansion valve 6, and includes a plurality of straight portions 31 to 35 that extend linearly and a plurality of curved portions 36 to 39 that connect the ends of the straight portions 31 to 35, and the bending angles A1 to A4 of each of the curved portions 36 to 39 are obtuse angles or right angles. This allows the refrigerant in a gas-liquid two-phase state that has flowed into the refrigerant circulation pipe 30 after passing through the expansion valve 6 to flow into the plate-type water-refrigerant heat exchanger 10 while suppressing the effects of centrifugal force. This makes it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 to be in a mixed state of liquid and gas phases.

[0050] As in this embodiment, the refrigerant circulation piping 30 may have a first straight section 31 which is a straight section connected to the plate-type water-refrigerant heat exchanger 10, a first curved section 36 which is a curved section connected to the first straight section 31, and a second straight section 32 which is a straight section connected to the first curved section 36, and the second straight section 32 may be configured to extend upward from the first curved section 36. This allows the direction of gravity acting on the refrigerant to be closer to the direction of the refrigerant flow in the second straight section 32, which the refrigerant passes through immediately before flowing into the plate-type water-refrigerant heat exchanger 10, making it easier to maintain or promote mixing of the gas and liquid phases. This makes it easier to keep the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 in a mixed state of liquid and gas phases. In particular, in this embodiment, the second straight portion 32 extends parallel to the vertical direction, so that the direction of gravity and the direction of the refrigerant flow coincide with each other, making it easy to maintain or promote mixing of the gas phase and the liquid phase.

[0051] As in this embodiment, the second straight portion 32 of the refrigerant circulation pipe 30 may be configured to be longer than the first straight portion 31. This makes it possible to lengthen the second straight section 32, which tends to maintain or promote mixing of the gas and liquid phases of the refrigerant, and to shorten the first straight section 31 between the second straight section 32 and the plate-type water-refrigerant heat exchanger 10. This makes it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 to be in a mixed state of liquid and gas phases.

[0052] As in this embodiment, the refrigerant circulation pipe 30 may be configured such that the inner diameter D1 on the side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 on the side closer to the expansion valve 6 (the side closer to the receiver tank 46). This makes it possible to easily improve the flow rate of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 while suppressing an increase in the piping resistance of the refrigerant circulation piping 30. As a result, it is possible to easily make the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 a mixed state of liquid and gas phases while suppressing a decrease in efficiency when the refrigerant flow rate is high. In particular, in this embodiment, the refrigerant circulation piping 30 is composed of a second piping member 43 connected to the expansion valve 6 via piping 47 and a receiver tank 46, and a first piping member 41 having an inner diameter D1 smaller than the inner diameter D3 and fixed to the second piping member 43, so that a refrigerant circulation piping 30 having different inner diameters D1 and D3 can be realized with a simple configuration.

[0053] As in the present embodiment, the first straight section 31, which is a straight section connected to the plate-type water-refrigerant heat exchanger 10, may be configured to be covered from the outside with a connecting pipe 45 connectable to the plate-type water-refrigerant heat exchanger 10. This allows the use of a pipe including the first piping member 41 with a diameter smaller than that of the plate-type water-refrigerant heat exchanger 10 as the refrigerant circulation pipe 30, making it easy to improve the flow rate of the refrigerant. Also, by covering the connecting pipe 45 from the outside, the area where the inner diameter increases immediately before the plate-type water-refrigerant heat exchanger 10 can be reduced, making it difficult for the flow rate to decrease. Therefore, with a simple configuration, the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily made into a mixed state of liquid and gas phases. In particular, in this embodiment, the left end of the first piping member 41 extends to the left side to a position that is substantially aligned with the left end of the connecting piping 45, making it easier to maintain the flow velocity until just before the refrigerant flows into the plate-type water-refrigerant heat exchanger 10.

[0054] As in this embodiment, the outer diameter D2 of at least a portion of the refrigerant circulation pipe 30 may be 3.50 mm or less per 1.0 kg / min of refrigerant circulation rate passing through the inside. This makes it easier to ensure the flow velocity of the refrigerant, and therefore makes it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 to be in a mixed state of liquid and gas phases. In particular, in this embodiment, the outer diameter D2 is 3.50 mm or less per 1.0 kg / min refrigerant circulation rate in the energy saving mode, in which the refrigerant circulation rate is likely to be low and it is difficult to ensure a sufficient refrigerant flow rate. Therefore, in many operation modes of the refrigeration system 1, the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily kept in a mixed state of liquid and gas phases.

[0055] As in this embodiment, the refrigeration system 1 includes an expansion valve 6, a plate-type water-refrigerant heat exchanger 10, and a refrigerant circulation pipe 30 connected to the plate-type water-refrigerant heat exchanger 10 and provided between the expansion valve 6 and the plate-type water-refrigerant heat exchanger 10, and the refrigerant circulation pipe 30 includes a plurality of straight portions 31 to 35 extending linearly and a plurality of curved portions 36 to 39 connecting the ends of the straight portions 31 to 35, and the bending angles A1 to A4 of each of the curved portions 36 to 39 are obtuse angles or right angles. This allows the refrigerant in a gas-liquid two-phase state that has flowed into the refrigerant circulation pipe 30 after passing through the expansion valve 6 to flow into the plate-type water-refrigerant heat exchanger 10 while suppressing the effects of centrifugal force. This makes it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 to be in a mixed state of liquid and gas phases.

[0056] [1-4. Example] The inventors conducted an experiment to verify the optimum outer diameter D2 and inner diameter D1 for the amount of refrigerant circulating. The experiment conducted by the inventors will be described below.

[0057] The inventors conducted a first and a second preliminary verification before conducting the following experiment. In the first preliminary verification, the inventors performed cooling operation on the refrigeration system 1 using a pipe having a curved section with an acute bend angle immediately before the connection with the first refrigerant-side connection port 11 instead of the refrigerant circulation pipe 30. The inventors found in the first preliminary verification that the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 were not sufficiently mixed. From this result, the inventors suggested that the bend angle of the curved section should not be an acute angle in order to suppress the centrifugal force acting on the gas-liquid two-phase refrigerant.

[0058] In addition, in a second preliminary verification, the inventors performed cooling operation on the refrigeration system 1 using a pipe without an acute bend angle instead of the refrigerant circulation pipe 30. The pipe in the second preliminary verification had three straight sections and two curved sections extending approximately horizontally just before the connection with the first refrigerant side connection port 11. Furthermore, a portion of the pipe had a smaller diameter than the pipe used in the first preliminary verification. In the second preliminary verification, the inventors found that the degree of mixing of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 was better than in the first preliminary verification, but still insufficient. From the results of the second preliminary verification, the inventors suggested that increasing the refrigerant flow velocity by narrowing the pipe diameter is effective in improving the mixing state of the gas and liquid phases of the refrigerant. Furthermore, the inventors found from the results of the second preliminary verification that if the portion of the piping that extends horizontally is long just before the connection with the first refrigerant side connection port 11, the gas phase and liquid phase of the refrigerant will be more likely to separate due to the action of gravity.

[0059] Based on the suggestions obtained from the first and second preliminary verifications, the inventors came up with the shape of the refrigerant circulation pipe 30 described in the first embodiment. Thereafter, the inventors conducted the following experiment to verify the specific pipe diameter of the refrigerant circulation pipe 30.

[0060] In the experiment, the inventors performed cooling operation on the refrigeration system 1 with three patterns of refrigerant circulating pipes 30 connected between the expansion valve 6 and the plate-type water-refrigerant heat exchanger 10, each having different outer and inner diameters. Specifically, the outer diameters D2 of the refrigerant circulating pipes 30 used by the inventors were 12.7 mm (½ inch), 9.52 mm (⅜ inch), and 7.94 mm (2.5 / 8 inches), respectively. In addition, the thickness of the first piping member 41 in each pattern of refrigerant circulating pipes 30 was 0.8 mm. Therefore, the inner diameters D1 of the patterns of refrigerant circulating pipes 30 used by the inventors were 11.1 mm, 7.92 mm, and 6.34 mm, respectively.

[0061] The inventors performed cooling operation on the refrigeration system 1 using the above-mentioned three patterns of refrigerant circulation pipes 30. Then, the inventors determined whether the gas phase and liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 were sufficiently mixed based on the suction pressure of the compressor 2. That is, the inventors determined that when the suction pressure of the compressor 2 was high, the gas phase and liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 were sufficiently mixed, and that when the suction pressure of the compressor 2 was low, the gas phase and liquid phase of the refrigerant were not sufficiently mixed.

[0062] For example, when a pipe with a curved section that is not an acute angle was used instead of the pipe with an acute bend angle used in the first preliminary verification, the suction pressure of the compressor 2 increased by 0.007 MPa (approximately 1.6%) and the refrigeration capacity improved by approximately 2.4%. The power consumption of both cases was almost the same (2.599 kW and 2.600 kW). Based on this, the inventors determined that the degree of mixing of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be improved by not making the bend angle of the upper curved section an acute angle.

[0063] The reason why the degree of mixing of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be determined from the suction pressure of the compressor 2 is that an increase in the suction pressure of the compressor 2 improves the refrigeration capacity of the refrigeration system 1. An increase in the suction pressure means that the evaporation performance of the plate-type water-refrigerant heat exchanger 10 is improved. Furthermore, since the evaporation capacity of the plate-type water-refrigerant heat exchanger 10 is improved, it can be determined that the heat absorption effect due to the heat of evaporation of the refrigerant in the plate-type water-refrigerant heat exchanger 10 is enhanced. Therefore, when the suction pressure of the compressor 2 is high, the gas and liquid phases of the refrigerant in the plate-type water-refrigerant heat exchanger 10 are likely to flow uniformly through each part of the plate-type water-refrigerant heat exchanger 10, and it can be determined that the gas and liquid phases of the refrigerant are sufficiently mixed.

[0064] As a result, the inventors determined that only in the pattern where the outer diameter D2 is 7.94 mm and the inner diameter D1 is 6.34 mm, the gas phase and liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 are sufficiently mixed.

[0065] FIG. 11 is a table showing various parameters of the refrigeration system 1 during the experiment, showing the operating conditions during the experiment. In FIG. 11, the "experimental values" indicate the various parameters used to determine whether the gas and liquid phases of the refrigerant were sufficiently mixed when the outer diameter D2 of the refrigerant circulation pipe 30 was 7.94 mm. In FIG. 11, the "reference values" indicate the various parameters when the frequency of the compressor 2 was 1 Hz lower than the "experimental values." During the experiment, the dry-bulb temperature of the outside air was 35°C, and the wet-bulb temperature was 24°C. Furthermore, during the experiment, the inlet temperature of water to the plate-type water-refrigerant heat exchanger 10 was 12°C, and the outlet temperature of water from the plate-type water-refrigerant heat exchanger 10 was 7°C.

[0066] 11, the amount of refrigerant circulating through the refrigerant circulation pipe 30 during cooling operation in this example was 2.16 kg / min. The amount of refrigerant circulating was calculated as the product of the volume of the compressor 2, the frequency of the compressor 2, and the suction density of the compressor 2.

[0067] Furthermore, the inventors found that, taking into consideration the difference between the "experimental value" and the "reference value," as well as measurement errors of various parameters, the calculated refrigerant circulation rate of 2.16 kg / min may contain an error of ±3.6%. Furthermore, the inventors took into consideration that the smaller the refrigerant circulation rate, the easier it is for the refrigerant to separate into its gas and liquid phases, and estimated the maximum refrigerant circulation rate during the experiment to be 2.27 kg / min, which is 1.05 times the calculated value.

[0068] From these results, the inventors concluded that in order to maintain the mixture of gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, it is desirable to set the outer diameter D2 to 7.94 mm or less when the refrigerant circulation rate is 2.27 kg / min or less. Also, the inventors concluded that in order to maintain the mixture of gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, it is desirable to set the inner diameter D1 to 6.34 mm or less when the refrigerant circulation rate is 2.27 kg / min or less.

[0069] The inventors also divided the outer diameter D2 and the inner diameter D1 by the refrigerant circulation rate to calculate the outer diameter D2 and the inner diameter D1 per 1.0 kg / min refrigerant circulation rate. As a result, the inventors concluded that in order to maintain a mixture of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, it is desirable to set the outer diameter D2 to 3.50 mm or less per 1.0 kg / min refrigerant circulation rate. The inventors also concluded that in order to maintain a mixture of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, it is desirable to set the inner diameter D1 to 2.93 mm or less per 1.0 kg / min refrigerant circulation rate.

[0070] (Other embodiments) As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the first embodiment above to create new embodiments. Therefore, other embodiments will be exemplified below.

[0071] In the first embodiment, the refrigerant circulation pipe 30 has been described as having five straight portions 31-35 and four curved portions 36-39, but this is just an example. There is no particular limit to the number of straight portions 31-35 and curved portions 36-39 formed in the refrigerant circulation pipe 30.

[0072] In the first embodiment, the second straight section 32 is described as being parallel to the vertical direction. The second straight section 32 may extend upward from the first straight section 31 side. Therefore, the second straight section 32 is not limited to being parallel to the vertical direction and may be inclined. However, if the second straight section 32 is parallel to the vertical direction, the direction in which gravity acts and the direction in which the refrigerant flows in the second straight section 32 will coincide, which has the effect of further promoting or easily maintaining the mixing of the gas phase and the liquid phase.

[0073] In the first embodiment, the refrigerant circulation piping 30 is described as being formed by brazing and integrating the first piping member 41, the second piping member 43, and the connecting piping 45, but this is just one example. The refrigerant circulation piping 30 may be made up of two or less, or four or more, members. Furthermore, the first piping member 41, the second piping member 43, and the connecting piping 45 of the refrigerant circulation piping 30 may be fixed by a fixing method other than brazing, such as welding.

[0074] In the first embodiment, the refrigeration device 1 is described as an outdoor unit of a hot water supply / heating device, but this is just one example. The refrigeration device 1 is not limited to an outdoor unit of a hot water supply / heating device, and may be any device that allows refrigerant that has been put into a gas-liquid two-phase state in the expansion valve 6 to flow through the plate-type water-refrigerant heat exchanger 10.

[0075] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0076] (Addendum) The above description of the embodiments discloses the following techniques. (Technology 1) A refrigerant circulation pipe connected to a plate-type water-refrigerant heat exchanger and provided between the plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe including a plurality of straight sections extending linearly and a plurality of curved sections connecting the ends of the straight sections, wherein the bending angle of each of the curved sections is an obtuse angle or a right angle. This allows the refrigerant in a gas-liquid two-phase state that has passed through the expansion valve and flowed into the refrigerant circulation pipe to flow into the plate-type water-refrigerant heat exchanger while suppressing the effects of centrifugal force, making it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger to be in a mixed state of liquid and gas phases.

[0077] (Technology 2) The refrigerant circulation pipe according to Technology 1, comprising: a first straight section which is the straight section connected to the plate-type water-refrigerant heat exchanger; a first curved section which is the curved section connected to the first straight section; and a second straight section which is the straight section connected to the first curved section, wherein the second straight section extends upward from the first curved section. This allows the direction of gravity acting on the refrigerant to be closer to the direction of the refrigerant flow in the second straight section that the refrigerant passes through just before entering the plate-type water-refrigerant heat exchanger, making it easier to maintain or promote mixing of the gas and liquid phases, and therefore makes it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger to be in a mixed state of liquid and gas phases.

[0078] (Technical Aspect 3) The refrigerant circulation pipe according to Technical Aspect 2, wherein the second straight portion is longer than the first straight portion. This allows the second straight section, which tends to maintain or promote the mixing of the gas and liquid phases of the refrigerant, to be long, and the first straight section between the second straight section and the plate-type water-refrigerant heat exchanger to be short, making it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger to be in a mixed state of liquid and gas phases.

[0079] (Technical Aspect 4) The refrigerant circulation pipe according to any one of Technical Aspects 1 to 3, wherein the inner diameter of the pipe on the side closer to the plate-type water-refrigerant heat exchanger is smaller than the inner diameter of the pipe on the side closer to the expansion valve. This makes it possible to easily increase the flow rate of the refrigerant flowing into the plate-type water-refrigerant heat exchanger while suppressing an increase in the piping resistance of the refrigerant circulation piping, thereby making it possible to easily make the refrigerant flowing into the plate-type water-refrigerant heat exchanger a mixed state of liquid and gas phases while suppressing a decrease in efficiency when the refrigerant flow rate is high.

[0080] (Technology 5) The refrigerant circulation piping according to any one of Technologies 1 to 4, wherein a first straight section, which is the straight section connected to the plate-type water-refrigerant heat exchanger, is covered from the outside with a connection piping connectable to the plate-type water-refrigerant heat exchanger. This allows the use of piping for refrigerant circulation with a smaller diameter than that of the plate-type water-refrigerant heat exchanger, making it easier to improve the refrigerant flow rate. Furthermore, by covering the connecting piping from the outside, the area where the inner diameter increases immediately before the plate-type water-refrigerant heat exchanger can be reduced, making it less likely that the flow rate will decrease. Therefore, with a simple configuration, the refrigerant flowing into the plate-type water-refrigerant heat exchanger can be easily mixed in liquid and gas phases.

[0081] (Technology 6) The refrigerant circulation pipe according to any one of Technologies 1 to 5, wherein the outer diameter of at least a part of the pipe is 3.50 mm or less per 1.0 kg / min of refrigerant circulation rate passing through the pipe. This makes it easier to ensure the flow velocity of the refrigerant, and therefore makes it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger to be in a mixed state of liquid and gas phases.

[0082] (Technology 7) A refrigeration system comprising: an expansion valve; a plate-type water-refrigerant heat exchanger; and a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, wherein the refrigerant circulation pipe includes a plurality of straight portions extending linearly and a plurality of curved portions connecting ends of the straight portions, and the bending angle of each of the curved portions is an obtuse angle or a right angle. This allows the refrigerant in a gas-liquid two-phase state that has passed through the expansion valve and flowed into the refrigerant circulation pipe to flow into the plate-type water-refrigerant heat exchanger while suppressing the effects of centrifugal force, making it easier for the refrigerant flowing into the plate-type water-refrigerant heat exchanger to be in a mixed state of liquid and gas phases. [Industrial Applicability]

[0083] The present disclosure is applicable to a refrigerant circulation pipe connected to a plate-type water-refrigerant heat exchanger and provided between the plate-type water-refrigerant heat exchanger and an expansion valve, and to a refrigeration system having such a refrigerant circulation pipe. Specifically, the present disclosure is applicable to a device having a heat exchanger that exchanges heat between water and a refrigerant, such as an outdoor unit of a heat pump-type hot water heater or space heater, and to a refrigerant circulation pipe provided in such a device. [Explanation of symbols]

[0084] 1 Refrigeration equipment 1a Bottom plate 2 Compressor 3. Flow path switching mechanism 4. Air heat exchanger 5. Blower 6 Expansion valve 7 Blower room 8 Machine room 8a Support member 9 Partition 10. Plate-type water-refrigerant heat exchanger 11 First refrigerant side connection port 12 Second refrigerant side connection port 13 Gas side piping 14 First water connection port 15 Second water connection port 16 Circulation pump 16a Valve 17 Gas-liquid separator 18 Outlet side water piping 18a Valve 19 Flow Sensor 30 Refrigerant circulation piping 31 1st straight line section (straight line section) 32 2nd straight line section (straight line section) 33 3rd straight line section (straight line section) 34 4th straight line section (straight line section) 35 5th straight line section (straight line section) 35a protrusion 36 First curved section (curved section) 37 Second curved section (curved section) 38 Third curved section (curved section) 39 Fourth curved section (curved section) 41 First piping member 42a, 42b protrusions 43 Second piping member 45 Connecting pipe 46 Receiver Tank 47 Piping

Claims

1. A refrigerant circulation pipe connected to a plate-type water-refrigerant heat exchanger and provided between the plate-type water-refrigerant heat exchanger and an expansion valve, a plurality of linear portions extending linearly; a plurality of curved portions that connect the ends of the straight portions, The bend angle at each of the curved portions is an obtuse angle or a right angle. Piping for refrigerant circulation.

2. a first straight portion which is the straight portion connected to the plate-type water-refrigerant heat exchanger; a first curved portion that is the curved portion connected to the first straight portion; a second straight portion that is the straight portion connected to the first curved portion, The second straight portion extends upward from the first curved portion. The refrigerant circulation pipe according to claim 1.

3. The second linear portion is longer than the first linear portion. The refrigerant circulation pipe according to claim 2.

4. an inner diameter on a side closer to the plate-type water-refrigerant heat exchanger is smaller than an inner diameter on a side closer to the expansion valve; The refrigerant circulation pipe according to claim 1.

5. a first straight section, which is the straight section connected to the plate-type water-refrigerant heat exchanger, is covered from the outside with a connection pipe connectable to the plate-type water-refrigerant heat exchanger; The refrigerant circulation pipe according to claim 4.

6. At least a part of the outer diameter is 3.50 mm or less per 1.0 kg / min of refrigerant circulation rate passing through the inside. The refrigerant circulation pipe according to claim 1.

7. An expansion valve; a plate-type water-refrigerant heat exchanger; a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, The refrigerant circulation pipe includes a plurality of straight sections extending linearly and a plurality of curved sections connecting ends of the straight sections, and a bending angle of each of the curved sections is an obtuse angle or a right angle. Refrigeration equipment.

Images