JP2024057108A - Refrigeration equipment heat source unit - Google Patents

Abstract

[Problem] In a refrigeration system using a CO2 refrigerant, it is desired to make the intermediate heat exchanger function more efficiently. [Solution] A heat source unit 10 of a refrigeration system 1 includes a compressor 2 that performs multiple-stage compression, a main heat exchanger 4, 45 that performs heat exchange between the refrigerant and a fluid, and a sub-heat exchanger 7, 46, 47. The sub-heat exchangers 7, 46, 47 are arranged independently of the main heat exchangers 4, 45, and are arranged upstream or downstream of the main heat exchangers 4, 45 in the flow of the fluid. [Selected Figure] Figure 8A

Description

A heat source unit for a refrigeration system that uses _CO2 refrigerant and exchanges heat between the _CO2 refrigerant and other fluids.

In a refrigeration system using a _CO2 refrigerant, a compressor that performs two-stage compression and an intermediate heat exchanger are used. In Patent Document 1 (JP 2009-150641 A), the intermediate heat exchanger is disposed above the heat source side heat exchanger.

In refrigeration systems using _CO2 refrigerant, there is a demand for more efficient operation of intermediate heat exchangers.

In addition, when the heat source side heat exchanger has a main heat exchanger and a secondary heat exchanger, there is also a demand to improve the efficiency of the secondary heat exchanger.

The heat source unit of the first aspect is a heat source unit of a refrigeration device that uses a _CO2 refrigerant and exchanges heat between the _CO2 refrigerant and another fluid. The heat source unit includes a compressor, a main heat exchanger, and an auxiliary heat exchanger. The compressor performs two or more stages of compression. The main heat exchanger exchanges heat between the refrigerant and the fluid. The auxiliary heat exchanger is arranged independently of the main heat exchanger and exchanges heat with the fluid. The auxiliary heat exchanger is arranged upstream or downstream of the main heat exchanger in the flow of the fluid. Here, "independent" means that the fins of the main heat exchanger and the fins of the auxiliary heat exchanger are not connected, and the main heat exchanger and the auxiliary heat exchanger have separate refrigerant inlets and outlets.

A heat source unit according to a first aspect, in a heat source unit using a _CO2 refrigerant which has a large temperature change in a heat exchanger, ensures a temperature difference between the fluid and the refrigerant, thereby increasing the efficiency of heat exchange.

The heat source unit of the second aspect is the heat source unit of the first aspect, and the auxiliary heat exchanger is an intermediate heat exchanger. The intermediate heat exchanger exchanges heat between the refrigerant and the fluid after the first stage of compression by the compressor and before the final stage of compression. The intermediate heat exchanger is disposed upstream of the main heat exchanger in the flow of the fluid.

In the heat source unit of the second aspect, the intermediate heat exchanger is arranged independently of and upstream of the main heat exchanger, which allows for sufficient heat exchange between the fluid and the refrigerant, improving the heat exchange efficiency.

The heat source unit of the third aspect is the heat source unit of the second aspect, further comprising a fan and a housing. In the third aspect, the fluid is air. The fan is for sending air to the main heat exchanger. The housing houses a compressor, the main heat exchanger, the fan, and the intermediate heat exchanger. The fan blows the air sucked in from the side of the housing upward from the top surface of the housing.

The third aspect of the heat source unit increases the heat exchange efficiency between the air and the refrigerant.

The heat source unit of the fourth aspect is the heat source unit of the third aspect, in which the intermediate heat exchanger is positioned at a height above half the height of the main heat exchanger.

In the heat source unit of the fourth aspect, the intermediate heat exchanger is positioned in a position where the wind speed is high, so the heat exchange amount of the intermediate heat exchanger is increased and efficiency is improved.

The heat source unit of the fifth aspect is the heat source unit of the first aspect, further comprising an expansion mechanism. The auxiliary heat exchanger is connected between the main heat exchanger and the expansion mechanism in the refrigerant circuit. The auxiliary heat exchanger is disposed upstream of the main heat exchanger in the fluid flow.

In the heat source unit of the fifth aspect, when the main heat exchanger is operated as a radiator, the secondary heat exchanger is positioned upstream of the main heat exchanger, thereby ensuring a temperature difference between the low-temperature refrigerant flowing through the secondary heat exchanger and the fluid, thereby improving the heat exchange efficiency.
The heat exchange amount of the intermediate heat exchanger is increased, improving efficiency.

The heat source unit of the sixth aspect is the heat source unit of the fifth aspect, further comprising a fan and a housing. In the sixth aspect, the fluid is air. The fan is for sending air to the main heat exchanger. The housing houses a compressor, a main heat exchanger, a fan, and a secondary heat exchanger. The fan blows the air sucked in from the side of the housing upward from the top surface of the housing.

The sixth aspect of the heat source unit increases the heat exchange efficiency between the air and the refrigerant.

The heat source unit of the seventh aspect is the heat source unit of the sixth aspect, in which the secondary heat exchanger is positioned at a height higher than half the height of the main heat exchanger.

In the heat source unit of the seventh aspect, the secondary heat exchanger is positioned at a position where the wind speed is high, so the amount of heat exchanged by the secondary heat exchanger is increased, improving efficiency.

The heat source unit of the eighth aspect is the heat source unit of the first aspect, further comprising an expansion mechanism. The auxiliary heat exchanger is connected to the refrigerant inlet/outlet of the main heat exchanger in the refrigerant circuit, which is farther from the expansion mechanism. The auxiliary heat exchanger is disposed downstream of the main heat exchanger in the fluid flow.

In the heat source unit of the eighth aspect, when the main heat exchanger is used as a radiator, the secondary heat exchanger is disposed downstream of the main heat exchanger, but because the temperature flowing through the secondary heat exchanger is high, a temperature difference with the fluid can be ensured. Overall, the heat exchange efficiency can be increased.

The heat source unit of the ninth aspect is the heat source unit of the eighth aspect, further comprising a fan and a housing. In the eighth aspect, the fluid is air. The fan is for sending air to the main heat exchanger. The housing houses a compressor, a main heat exchanger, a fan, and a secondary heat exchanger. The fan blows the air sucked in from the side of the housing upward from the top surface of the housing.

The ninth aspect of the heat source unit increases the heat exchange efficiency between the air and the refrigerant.

The heat source unit of the tenth aspect is the heat source unit of the ninth aspect, in which the secondary heat exchanger is positioned at a height higher than half the height of the main heat exchanger.

In the heat source unit of the tenth aspect, the secondary heat exchanger is disposed in a position where the wind speed is high, so the amount of heat exchanged by the secondary heat exchanger is increased, improving efficiency.

FIG. 1 is a refrigerant circuit diagram of a refrigeration device 1 according to a first embodiment. FIG. 2 is a schematic perspective view of the heat source unit 10 of the first embodiment. FIG. 2 is a schematic perspective view of a portion of the heat source side heat exchanger 4 of the first embodiment. FIG. 4 is a side view of the vicinity of a folded portion 33 of the heat exchanger 4 of the first embodiment. 13 is a cross-sectional view of the heat exchanger 4 of the modified example 1A near a folded portion 33. FIG. FIG. 3 is a longitudinal sectional view of a joint 34 according to the first embodiment. FIG. 4 is a cross-sectional view of the joint 34 of the first embodiment. FIG. 11 is a cross-sectional view of a heat transfer tube 30 at cross section S in a heat exchanger according to modified example 1E. FIG. 11 is a cross-sectional view of a heat transfer tube 30 at a cross section S in a heat exchanger 4 of a modified example 1D. FIG. 13 is a side view of a first end 4a of the heat exchanger 4 of modification example 1D. FIG. 13 is a side view of the second end 4b of the heat exchanger 4 of the modified example 1D. FIG. 2 is a top view of the heat exchanger 4 and the intermediate heat exchanger 7 according to the first embodiment. FIG. 2 is a cross-sectional view of a heat exchanger 4 and an intermediate heat exchanger 7 of the first embodiment, taken along a cross section S. FIG. 11 is a top view of a heat exchanger 4 and a sub-heat exchanger 46 according to a second embodiment. FIG. 11 is a cross-sectional view of a heat exchanger 4 and a sub-heat exchanger 46 of a second embodiment taken along a cross section S. FIG. 13 is a top view of a heat exchanger 4 and a sub-heat exchanger 47 according to a third embodiment. FIG. 11 is a cross-sectional view of a heat exchanger 4 and a sub-heat exchanger 47 of a third embodiment taken along a cross section S.

First Embodiment
(1) Refrigerant circuit configuration of refrigeration device 1 The refrigerant circuit configuration of the refrigeration device 1 of the first embodiment is shown in Fig. 1. The refrigeration device 1 of this embodiment is a device that performs a two-stage compression refrigeration cycle using carbon dioxide, which is a refrigerant that operates in the supercritical region. The refrigeration device 1 of this embodiment can be used in air conditioners that perform heating and cooling, hot and cold water heaters, etc.

The refrigerant circuit of the refrigeration device 1 of this embodiment mainly includes a compressor 2, a four-way switching valve 3, a heat source side heat exchanger 4, an expansion mechanism 5, a user side heat exchanger 6, and an intermediate heat exchanger 7.

The compressor 2 is a two-stage compressor that compresses the refrigerant in two stages using two compression elements 2c and 2d. The compressor 2 draws in the refrigerant from the suction pipe 2a, compresses the drawn refrigerant using the first-stage compression element 2c, and then discharges it into the intermediate refrigerant pipe 8. The refrigerant discharged into the intermediate refrigerant pipe 8 is further drawn into the second-stage compression element 2d, compressed, and discharged into the discharge pipe 2b. The discharge pipe 2b is a refrigerant pipe for sending the refrigerant discharged from the compressor 2 to the four-way switching valve 3. The discharge pipe 2b is provided with an oil separator 41 and a check valve 42. The oil separator 41 separates the refrigerating machine oil mixed with the refrigerant discharged from the compressor 2 from the refrigerant. The separated oil is decompressed by the capillary tube 41c and returned to the suction pipe 2a of the compressor 2 via the oil return pipe 41b.

The refrigerating machine oil of the present embodiment is not particularly limited as long as it is a refrigerating machine oil that can be used with a _CO2 refrigerant. Examples of the refrigerating machine oil include PAG (polyalkylene glycols) and POE (polyol esters).

The four-way switching valve 3 can switch the flow of refrigerant through the path connecting the heat source side heat exchanger 4, the expansion mechanism 5, and the utilization side heat exchanger 6 between forward and reverse. During cooling, the refrigerant flowing out of the compressor 2 is made to flow from the heat source side heat exchanger 4 to the utilization side heat exchanger 6. At this time, the heat source side heat exchanger 4 is a radiator, and the utilization side heat exchanger 6 is an evaporator. During heating, conversely, the refrigerant flowing out of the compressor 2 is made to flow from the utilization side heat exchanger 6 to the heat source side heat exchanger 4. At this time, the utilization side heat exchanger 6 is a radiator, and the heat source side heat exchanger 4 is an evaporator.

An intermediate heat exchanger 7 and a check valve 15 are provided in the middle of the intermediate refrigerant pipe 8. That is, the refrigerant compressed by the first-stage compression element 2c exchanges heat with air in the intermediate heat exchanger 7 and flows back into the second-stage compression element 2d.

The intermediate refrigerant pipe 8 is provided with an intermediate heat exchanger bypass pipe 9 so as to bypass the intermediate heat exchanger 7. That is, the refrigerant that has flowed through the first-stage compression element 2c and the intermediate heat exchanger bypass pipe 9 flows into the second-stage compression element 2d without passing through the intermediate heat exchanger 7. Opening and closing valves 11 and 12 are used to switch whether the refrigerant flows through the intermediate heat exchanger 7 or the intermediate heat exchanger bypass pipe 9. Basically, when the utilization side heat exchanger 6 is used as an evaporator, the refrigerant is controlled to flow through the intermediate heat exchanger 7, and conversely, when the utilization side heat exchanger 6 is used as a radiator, the refrigerant is controlled to flow through the intermediate heat exchanger bypass pipe 9. That is, the intermediate heat exchanger 7 is basically used for cooling.

The refrigeration device 1 of this embodiment uses a two-stage compressor, but the same applies when two compressors are used. A compressor or compression mechanism with three or more stages may also be used.

The expansion mechanism 5 is either an expansion valve, a capillary tube, or an expander.

(2) Configuration of Heat Source Unit 10 of Refrigeration System 1 (2-1) Overall Configuration of Heat Source Unit 10 Components of the heat source unit 10 of the refrigeration system 1 of this embodiment are shown by dotted lines in FIG. 1, and the external appearance is shown in a perspective view in FIG.

The heat source unit 10 contains a fan 40, a compressor 2, a heat source side heat exchanger 4, an intermediate heat exchanger 7, an expansion mechanism 5, a four-way switching valve 3, and an oil separator 41 within a housing 20.

(2-2) Heat source side heat exchanger 4
FIG. 2 is an external perspective view of the heat source unit 10, and FIG. 3A is a perspective view of a portion of the heat source side heat exchanger 4. As shown in FIG.

As shown in FIG. 2, the heat source side heat exchanger 4 of this embodiment is arranged on three sides inside the housing 20 of the heat source unit 10. When the fan 40 rotates, air around the housing 20 is taken in from the three sides and passes through the heat source side heat exchanger 4. The air that has entered the housing 20 passes through the fan 40 and is blown out upward from the top surface of the housing 20. Therefore, the heat source unit 10 of this embodiment is an upward blowing type. The air exchanges heat with the refrigerant while passing through the heat exchanger 4, and is heated or cooled.

The schematic of one side of the heat source side heat exchanger 4 of this embodiment is shown in the perspective view of FIG. 3. The heat exchanger 4 has a heat transfer tube 30 through which a refrigerant flows, and metal fins 50 that promote heat exchange between the refrigerant and air. The heat transfer tube 30 of this embodiment is a multi-hole flat tube. In the multi-hole flat tube, multiple holes through which the refrigerant flows are aligned in the width direction.

In the heat exchanger 4 of this embodiment, as shown in FIG. 2, the refrigerant is introduced into the heat transfer tube 30 at the first end 4a from outside the heat exchanger 4. The refrigerant flows from the first end 4a along the three sides of the heat transfer tube 30, which is bent 90° at two points, to the second end 4b. When the refrigerant reaches the second end 4b, the flow direction is reversed by 180°, and after flowing along the three sides again, it returns to the first end 4a. The refrigerant flows out of the heat exchanger 4 from the heat transfer tube 30 at the first end 4a. Here, the heat transfer tube that forms the refrigerant flow path from the first end 4a to the second end 4b is referred to as the first heat transfer tube 30a, and the heat transfer tube that flows the refrigerant in the opposite direction is referred to as the second heat transfer tube 30b.

In this embodiment, as shown in FIG. 3, the heat transfer tubes 30 are arranged in two rows with respect to the air flow. In each row, the first heat transfer tubes 30a and the second heat transfer tubes 30b are arranged alternately above and below.

In addition, in this specification, the direction of refrigerant flow in the heat exchanger 4 is basically described as being used as a radiator. When used as an evaporator, the direction of the refrigerant is reversed.

(2-3) Configuration of the turn-back portion 33 The configuration of the vicinity of the second end 4b of the heat source side heat exchanger 4 of this embodiment will be described with reference to the drawings. A turn-back portion 33 is disposed at the second end 4b. Fig. 4 is a vertical cross-sectional view of the refrigerant turn-back portion 33. Here, the portion near the second end 4b of the first heat transfer tube 30a is referred to as a first straight portion 31, and the portion near the second end 4b of the second heat transfer tube 30b is referred to as a second straight portion 32.

The turn-back section 33 reverses the direction of the refrigerant that has flowed through the first straight section 31 of the heat transfer tube 30 (multi-hole flat tube 300) and directs it to flow into the second straight section 32 below the first straight section 31.

The folded section 33 is formed using two joints 34a and 34b and a U-shaped tube 350. The joints 34a and 34b connect the heat transfer tube 30 and the U-shaped tube 350.

In this embodiment, the heat transfer tube 30 may be a multi-hole flat tube or a circular tube, and is not particularly limited. In this embodiment, a multi-hole flat tube 300 is used. A multi-hole flat tube has high heat transfer performance between the refrigerant and the heat transfer tube. In the multi-hole flat tube 300 of this embodiment, multiple holes are arranged in a row, and the arrangement direction of the holes in the multi-hole flat tube is called the width direction, and the direction perpendicular to the width direction and the flow direction of the refrigerant is called the thickness direction. If the thickness (length in the thickness direction) of the multi-hole flat tube is T and the width (length in the width direction) is W, then W>T.

In this embodiment, the refrigerant that flows through the flow paths, which are the multiple holes of the multi-hole flat tube 300, is collected into one flow path at the turn-back section 33. Therefore, the refrigerant is homogenized at the turn-back section 33, i.e., the joints 34a, 34b and the U-shaped tube.

In this embodiment, the vertical thickness T of the heat transfer tube 30 is 3 mm or less. Also, the vertical distance DP between the center of the first straight section 31 and the center of the second straight section 32 is 0 mm to 21 mm.

In this embodiment, in the heat exchanger 4 using _CO2 refrigerant, the first straight portion 31 and the second straight portion 32, which sandwich the folded portion 33 of the heat transfer tube 30, are arranged close to each other. This makes it possible to suppress temperature unevenness of the passing air. As a result, the heat exchange efficiency is also improved.

In the heat exchanger 4 of this embodiment, the vertical distance DP between the center of the first straight section 31 and the center of the second straight section 32 is 5 times or less than the vertical thickness T of the heat transfer tube 30.

In this embodiment, in the heat exchanger 4 using the _CO2 refrigerant, the first straight portion 31 and the second straight portion 32 sandwiching the folded portion 33 of the heat transfer tube 30 are arranged close to each other. This makes it possible to suppress temperature unevenness of the passing air.

The heat exchanger 4 of this embodiment further includes a plurality of fins 50. The fins 50 are fixed to the heat transfer tube 30 and promote heat exchange between the heat transfer tube 30 and the air. The fin pitch of the plurality of fins 50 is 1.3 mm or more, preferably 1.4 mm or more.

In the heat exchanger 4 of this embodiment, the vertical thickness T of the heat transfer tube 30 is 3 mm or less, and the fin pitch is 1.3 mm or more, which improves the heat exchange efficiency.

When the heat exchanger 4 of this embodiment is used as a radiator, the temperature difference between the refrigerant inlet temperature and the refrigerant outlet temperature of the heat exchanger 4 is 40°C or more.

In this embodiment, _CO2 refrigerant is used as the refrigerant. _CO2 refrigerant is a refrigerant used in a supercritical state, and the temperature drop of the refrigerant in the radiator is large, even reaching 40° C. or more. Since the temperature difference of the refrigerant is large, it is also effective to arrange the first straight portion 31 and the second straight portion 32 close to each other.

In the heat exchanger 4 of this embodiment, the second straight section 32 is located above or below the first straight section 31.

In the heat exchanger 4 of this embodiment, the first straight section 31 and the second straight section 32 are located one above the other, so the distance between them is short, which can further suppress temperature unevenness in the passing air. In addition, the top and bottom of the heat transfer tube 30 are connected by fins 50, so the surrounding temperatures are close through the fins 50.

The above describes the case where the refrigerant flowing through the first straight section 31 is folded back downward into the second straight section 32. The same applies when the refrigerant is folded back upward.

(2-4) Detailed Description of Joint 34 Fig. 5A is a vertical cross-sectional view of joint 34, and Fig. 5B is a horizontal cross-sectional view of joint 34. As shown in Figs. 5A and 5B, joint 34 of the present embodiment connects multi-hole flat tube 300 and circular tube 35. In this embodiment, circular tube 35 is a U-shaped tube 350. The refrigerant passed through the inside is _CO2 refrigerant.

The joint 34 has a first connection part 301, a main body part 302, and a second connection part 303. The first connection part 301 covers the outside of the end of the multi-hole flat tube 300. The main body part 302 is continuous with the first connection part 301. The second connection part 303 is continuous with the main body part. The second connection part 303 covers the outside of the end of the circular tube 35.

5A , when viewed in the vertical direction, the vertical inner diameter _L301 of the first connection portion 301 is slightly larger than the thickness T of the multi-hole flat tube 300. The vertical inner diameter L302 of the main body portion ₃₀₂ is larger than the vertical inner diameter _L301 of the first connection portion 301. In addition, in the main body portion 302, the vertical inner diameter _L302 increases as it moves away from the first connection portion 301, and becomes constant at a certain portion.

In the joint 34 of this embodiment, the inner diameter L ₃₀₂ in the vertical direction of the main body 302 is larger than the inner diameter L ₃₀₁ in the vertical direction of the first connection portion. Therefore, oil is less likely to accumulate around the connection portion on the inner circumferential surface of the joint 34.

In addition, in the joint 34 of this embodiment, the main body 302 has a region in which the inner diameter in the vertical direction gradually increases as it moves away from the first connection portion 301. This configuration makes it even more difficult for oil to remain around the connection portion on the inner surface of the joint 34.

On the other hand, when viewed in the horizontal direction, as shown in Fig. 5B, the horizontal inner diameter _W301 of the first connection portion 301 is slightly larger than the width W of the multi-hole flat tube 300. The horizontal inner diameter _W302 of the main body portion 302 is smaller than the horizontal inner diameter _W301 of the first connection portion 301. In addition, in the main body portion 302, the horizontal inner diameter _W302 decreases as it moves away from the first connection portion 301 and becomes constant at a certain portion. The portion where the horizontal inner diameter _W302 is constant has the same length as the portion where the vertical inner diameter _L302 is constant.

Since the inner diameter L ₃₀₂ in the vertical direction of the body 302 of the joint 34 is larger than the inner diameter L ₃₀₁ in the vertical direction of the first connection portion 301 , oil is less likely to remain on the inner surface of the first connection portion 301 near the multi-hole flat tube 300 .

Also, as shown in FIG. 5A, in this embodiment, the inner diameter of the circular pipe 35 connected to one side of the fitting 34 is larger than the diameter in the thickness direction of the hole of the multi-hole flat pipe 300 connected to the other side of the fitting 34.

Furthermore, the thickness of the tube of fitting 34 is thicker than the thickness of circular tube 35. The reason for making the tube of fitting 34 thicker is that fitting 34 has a flat portion and therefore requires greater strength than circular tube 35.

In addition, the joint 34 of this embodiment preferably further has a reinforcing member 304 arranged to extend vertically in the refrigerant flow path. The reinforcing member 304 is arranged near the first connection part 301. The first reinforcing member 304 connects the upper and lower parts of the tubes constituting the joint 34, and plays a role of reinforcing when the tubes are subjected to tensile stress or compressive stress from the upper and lower parts in FIG. 5A. Since the _CO2 refrigerant has a high pressure and the first connection part 301 has a flat shape, it is preferable to use the reinforcing member 304.

(2-4-1) Method for Manufacturing Joint 34 Two methods for manufacturing the joint 34 of this embodiment will be described.

The first manufacturing method for fitting 34 is to use a circular pipe.

The circular tube is a normal circular tube with a constant inner diameter. The wall thickness of the raw circular tube is thicker than the wall thickness of the circular tube 35 to be connected. To make the first connecting portion 301, one end of the circular tube is crushed flat. Then, the end is processed so that the vertical inner diameter L ₃₀₁ is slightly larger than the thickness T of the multi-hole flat tube 300, and the horizontal inner diameter W ₃₀₁ is slightly larger than the width W of the multi-hole flat tube 300.

As described above, the joint 34 of this embodiment is formed by processing one end of a circular pipe in one manufacturing method. The raw circular pipe has a wall thickness greater than the wall thickness of the circular pipe 35 to be connected. The base portion of the raw circular pipe is a part of the main body 302, a portion with constant inner diameters L ₃₀₂ and W ₃₀₂ .

The fitting 34 of this embodiment can be manufactured by simply processing a circular pipe, which helps keep manufacturing costs down.

This manufacturing method is relatively easy to manufacture, but it is difficult to insert the reinforcing member 304. Therefore, this manufacturing method is used when the reinforcing member 304 is not used.

The second manufacturing method for joint 34 is a bonding method.

In the joint 34 shown in Figure 5A, the upper and lower parts from the center are prepared separately. It is not necessary to make them exactly in half, and one part can be larger.

The reinforcing member 304 is first attached to the upper or lower part by brazing or the like. The upper and lower parts are then bonded together by brazing or the like to form the joint 34.

As described above, the joint 34 of this embodiment may be manufactured by laminating two or more members. By manufacturing by laminating, it is possible to easily manufacture joints with complex structures, such as those equipped with reinforcing members 304.

(2-5) Intermediate heat exchanger 7
The arrangement of the intermediate heat exchanger 7 in this embodiment will be described with reference to a top view in FIG. 8A and a cross-sectional view in FIG. 8B.

As shown in FIG. 8A, the intermediate heat exchanger 7 of this embodiment is disposed inside the housing 20 and outside the heat exchanger 4, independent of the heat exchanger 4. Here, "independent" means that the fins 50 of the heat exchanger 4 and the fins (not shown) of the intermediate heat exchanger 7 are not connected, and the heat exchanger 4 and the intermediate heat exchanger 7 have separate refrigerant inlets and outlets.

In addition, as shown in FIG. 8B, the intermediate heat exchanger is positioned at a height more than half the height at which heat exchanger 4 is positioned.

In the heat source unit 10 of this embodiment, the fan 40 is positioned above the heat exchanger 4 and the intermediate heat exchanger 7, and the wind speed increases the higher up the side of the heat exchanger 4.

The intermediate heat exchanger 7 is located upstream of the heat exchanger 4, ensuring a sufficient temperature difference between the air and the refrigerant and increasing the amount of heat exchange.

In addition, because the intermediate heat exchanger 7 is located at the top, the air volume is relatively large, allowing for a large amount of heat exchange.

(3) Features (3-1)
The heat source unit 10 of this embodiment is a heat source unit 10 of a refrigeration device 1 that uses _CO2 refrigerant and exchanges heat between the _CO2 refrigerant and another fluid. The heat source unit 10 includes a compressor 2, a heat source side heat exchanger 4, and an intermediate heat exchanger 7. The compressor 2 performs two or more stages of compression. The heat source side heat exchanger 4 exchanges heat between the refrigerant and air. The intermediate heat exchanger 7 exchanges heat between the refrigerant and the fluid after the first stage of compression by the compressor 2 and before the final stage of compression. The intermediate heat exchanger 7 is disposed upstream of the heat source side heat exchanger 4 in the flow of the fluid, independently of the heat source side heat exchanger 4. Here, independent means that the fins 50 of the heat exchanger 4 and the fins (not shown) of the intermediate heat exchanger 7 are not connected, and the heat exchanger 4 and the intermediate heat exchanger 7 have separate refrigerant inlets and outlets.

In this embodiment, the intermediate heat exchanger 7 is located upstream of the heat source side heat exchanger 4, so that it is easy to ensure a temperature difference with the air, even when the temperature of the _CO2 refrigerant is relatively low, enabling efficient heat exchange.

(3-2)
In the present embodiment, the heat source unit 10 further includes a fan 40 and a housing 20. The fan 40 is for sending air to the heat source side heat exchanger 4. The housing 20 houses the compressor 2, the heat source side heat exchanger 4, the fan 40, and the intermediate heat exchanger 7. The fan 40 blows air sucked in from a side surface of the housing upward from the top surface of the housing.

In the heat source unit 10 of this embodiment, the intermediate heat exchanger 7 is further disposed at a height above half the height of the heat source side heat exchanger 4.

In the heat source unit 10 of this embodiment, the intermediate heat exchanger 7 is positioned at a position where the wind speed is high, so the heat exchange amount of the intermediate heat exchanger 7 is increased, improving efficiency.

(4) Modifications (4-1) Modification 1A
In the first embodiment, the case where the folded portion 33 is configured using the joint 34 and the U-shaped tube 350 has been described. In the modified example 1A, as shown in FIG. 4B, one heat transfer tube is folded to form the first straight portion 31, the folded portion 33, and the second straight portion 32. In the modified example 1A, the heat transfer tube 30 may be a circular tube or a multi-hole flat tube. In the modified example 1A, a multi-hole flat tube is selected. The multi-hole flat tube is folded 180° in the thickness direction while the width direction of the multi-hole flat tube is left as it is. The thickness T of the heat transfer tube in the vertical direction is 3 mm or less. In this embodiment, the vertical distance DP between the center of the first straight portion 31 and the center of the second straight portion 32 is 21 mm or less.

In the heat exchanger 4 of variant 1A, the folded section 33 is constructed by folding the heat transfer tube 30 with a single tube, so the number of parts is small. In addition, since there are no connection points, problems such as refrigerant leakage at the connection points are unlikely to occur.

(4-2) Modification 1B
In the first embodiment, the case has been described in which the turn-back portion 33 is configured using the joint 34 and the U-shaped tube 350. In Modification 1B, a collecting pipe is used as the turn-back portion 33. In the collecting pipe, the refrigerant that has passed through the multiple heat transfer tubes 30a is mixed once, and then the flow direction of the refrigerant is reversed and the refrigerant is sent to another multiple heat transfer tubes 30b. The other configurations are the same as those of the first embodiment.

In the turn-back section 33 of variant 1B, a collecting pipe is used, so the refrigerant that has flowed through multiple heat transfer tubes 30a is merged in the collecting pipe. This allows the refrigerant temperature to be homogenized.

(4-3) Modification 1C
In the first embodiment, the joint 34 is separate from the multi-hole flat tube 300 and the circular tube 35. In the modification 1C, the joint 34 is integral with the circular tube 35. The other configurations are similar to those of the first embodiment.

In the joint 34 of modification 1C, similarly to the joint 34 of the first embodiment, the inner diameter _L302 in the vertical direction of the main body 302 is larger than the inner diameter _L301 in the vertical direction of the first connection portion. Therefore, oil is less likely to remain around the connection portion on the inner circumferential surface of the joint 34.

As an application of the joint 34 of variant 1A, the joint 34a, the U-shaped tube 350, and the joint 34b may be configured as a single unit to form the folded portion 33 as shown in FIG. 4.

(4-4) Modification 1D
(4-4-1) Configuration of heat exchanger 4 of modified example 1D In the heat exchangers 4 of the first embodiment and modified example 1A, the heat transfer tubes 30 are folded back in the vertical direction. That is, the first straight portion 31 and the second straight portion 32 belong to the same row. In the heat exchanger 4 of modified example 1D, the heat transfer tubes 30 are folded back across rows. The rest of the configuration of the refrigeration device 1 of modified example 1D is the same as that of the first embodiment and modified example 1A.

The configuration of the heat exchanger 4 of the modified example 1D will be described with reference to the drawings. 7A and 7B show the side view of the first end 4a and the second end 4b as viewed from the direction of refrigerant flow, and FIG. 6B shows a cross-sectional view of a cross section S perpendicular to the direction of refrigerant flow at the middle of the first end 4a and the second end 4b. As in the first embodiment, the first heat transfer tube 30a is a heat transfer tube that flows the refrigerant from the first end 4a to the second end 4b, and the second heat transfer tube 30b is the opposite. Also, in the modified example 1D, the flow of the refrigerant will be described assuming that the heat exchanger 4 is used as a radiator. When used as an evaporator, the flow of the refrigerant is reversed. In the modified example 1D, the heat transfer tube is a multi-hole flat tube. The vertical thickness T of the heat transfer tube 30 is 3 mm or less.

In the heat exchanger 4 of the modified example 1D, the refrigerant enters the first refrigerant inlet/outlet 401 shown in FIG. 7A. The refrigerant that flows through the first heat transfer tube 30a from the first refrigerant inlet/outlet 401 passes through the three sides of the heat exchanger 4, exchanges heat with the air, and reaches the second end 4b.

The refrigerant that reaches the second end 4b is folded back to another row (here, the adjacent row on the windward side) by the folding back section 33. At this time, the vertical distance DP between the center of the first heat transfer tube 30a (first straight section 31) and the center of the second heat transfer tube 30b (second straight section 32) is 21 mm or less. The configuration of the folding back section 33 in modification 1D is the same as that of modification 1A, and the first heat transfer tube 30a and the second heat transfer tube 30b are connected by two joints 34 and a U-shaped tube 350 that connects them.

The heat transfer tubes 30a, 30b of variant 1D are arranged vertically with a period P. The vertical distance DP between the center of the first heat transfer tube 30a (first straight section 31) and the center of the second heat transfer tube 30b (second straight section 32) is set to be greater than 0 and smaller than DP. In other words, 0<DP<P.

The refrigerant that is turned back at the second end 4b flows through the second heat transfer tube 30b, exchanges heat with the air as it passes through the three sides, and reaches the first end 4a. The refrigerant that reaches the first end flows out of the second refrigerant inlet/outlet 402 into the refrigerant circuit outside the heat exchanger 4.

In the above, in variant 1D, the first heat transfer tube 30a is placed downwind and the second heat transfer tube 30b is placed upwind. The reverse arrangement is also possible.

In addition, in the modification 1D, the heat transfer tube 30 is described as making only one round trip between the first end 4a and the second end 4b. The present invention is also effective when the heat transfer tube 30 makes two or more round trips.

(4-4-2) Features of the heat exchanger of the modified example 1D (4-4-2-1)
The first heat transfer tubes 30a and the second heat transfer tubes 30b before and after the turn-back portion 33 of the heat exchanger 4 of the modification 1D are in different adjacent rows. Therefore, when viewed in the same row, the first heat transfer tubes 30a and the second heat transfer tubes 30b with different refrigerant temperatures are not arranged side by side, and the temperature distribution within the row is suppressed.

(4-4-2-2)
In the heat exchanger 4 of variant example 1D, the first heat transfer tube 30a and the second heat transfer tube 30b before and after the turn-back portion 33 are in separate adjacent rows, and the vertical distance DP between the center of the first heat transfer tube 30a (first straight portion 31) and the center of the second heat transfer tube 30b (second straight portion 32) is set to be greater than 0 and smaller than DP.

This arrangement ensures that the second heat transfer tube 30b does not obstruct the first heat transfer tube 30a, which is located downwind, and promotes heat exchange between the air and the refrigerant.

(4-4-2-3)
In addition, the first refrigerant inlet/outlet 401 and the second refrigerant inlet/outlet 402 in the modification 1D are arranged in different rows. Therefore, for example, when a separate refrigerant collecting pipe is provided at the refrigerant inlet/outlet, the connecting piping can be easily configured simply.

(4-5) Modification 1E
6A shows a cross-sectional view of a cross section S perpendicular to the refrigerant flow direction at the midpoint between the first end 4a and the second end 4b of the heat exchanger 4 of the modified example 1E. The modified example 1E is different from the modified example 1D in that the vertical distance DP between the center of the first heat transfer tube 30a (first straight portion 31) and the center of the second heat transfer tube 30b (second straight portion 32) at the refrigerant turning back portion 33 at the second end 4b is 0. The other points are the same as the modified example 1D.

The heat exchanger of variant 1E has the same characteristics as the heat exchanger 4 of variant 1D, (4-4-2-1) and (4-4-2-3).

(4-6) Modification 1F
The heat source side heat exchanger 4 of the first embodiment exchanges heat between the _CO2 refrigerant flowing inside and the air. The fluid exchanging heat with the refrigerant is not limited to air. In the modified example 1F, the fluid is water. The configuration of the refrigerant circuit is the same as that of FIG. 1.

In the heat source unit of variant 1F, in the piping through which water flows, the water exchanges heat with the intermediate heat exchanger 7 on the upstream side, and the water exchanges heat with the heat source side heat exchanger 4 on the downstream side.

In the heat exchanger of variant 1F, when the heat source side heat exchanger 4 functions as a radiator, it is easier to ensure a temperature difference between the relatively low temperature refrigerant in the intermediate heat exchanger 7 and the water, improving the heat exchange efficiency.

Second Embodiment
(5) Auxiliary heat exchanger 46
In the first embodiment, the heat source side heat exchanger 4 is configured by one heat exchanger.

In the second embodiment, the heat source side heat exchanger 4 is composed of a main heat exchanger 45 and a sub-heat exchanger 46. The main heat exchanger 45 is mainly responsible for heat source side heat exchange. The sub-heat exchanger 46 is connected between the main heat exchanger 45 (corresponding to the heat source side heat exchanger 4 in FIG. 1) and the expansion mechanism 5 in the refrigerant circuit. In addition, in the second embodiment, the intermediate heat exchanger is not essential. Even if the intermediate heat exchanger 7 is present, its position is not particularly limited. The other configurations of the second embodiment are the same as those of the first embodiment.

The arrangement of the main heat exchanger 45 and the auxiliary heat exchanger 46 in this embodiment is explained using the top view in Figure 9A and the cross-sectional view in Figure 9B.

As shown in FIG. 9A, the auxiliary heat exchanger 46 of this embodiment is disposed inside the housing 20 and outside the main heat exchanger 45, independently of the main heat exchanger 45. Here, "independent" means that the fins 50 of the main heat exchanger 45 and the fins (not shown) of the auxiliary heat exchanger 46 are not connected, and the main heat exchanger 45 and the auxiliary heat exchanger 46 have separate refrigerant inlets and outlets. In addition, a refrigerant collecting section may be further disposed between the main heat exchanger 45 and the auxiliary heat exchanger 46 in the refrigerant circuit. By disposing the refrigerant collecting section, the refrigerant is collected once, and the refrigerant temperature, etc. are homogenized.

As shown in FIG. 9B, the secondary heat exchanger 46 is positioned at a height more than half the height at which the main heat exchanger 45 is positioned.

This configuration is particularly effective when the heat source side heat exchanger is used as a radiator. That is, in a radiator in a refrigeration cycle using a _CO2 refrigerant, the refrigerant temperature is higher at the refrigerant inlet and lower near the outlet. That is, in this embodiment, the refrigerant temperature is high in the main heat exchanger 45 and low in the auxiliary heat exchanger 46. That is, in the auxiliary heat exchanger 46, the temperature difference between the refrigerant and the air is small.

In the heat source unit 10 of this embodiment, the fan 40 is positioned above the main heat exchanger 45 and the auxiliary heat exchanger 46, and the wind speed increases the higher up the side of the heat exchanger 4.

The secondary heat exchanger 46 is located upstream of the main heat exchanger 45, ensuring a sufficient temperature difference between the air and the refrigerant and increasing the amount of heat exchange.

In addition, because the secondary heat exchanger 46 is located at the top, the air volume is relatively large, allowing for a large amount of heat exchange.

Third Embodiment
(6) Auxiliary heat exchanger 47
In the first embodiment, the heat source side heat exchanger 4 is configured by one heat exchanger.

In the third embodiment, the heat source side heat exchanger 4 is composed of a main heat exchanger 45 and a sub-heat exchanger 47. The main heat exchanger 45 is mainly responsible for heat source side heat exchange. The sub-heat exchanger 47 is connected to the main heat exchanger 45 (corresponding to the heat source side heat exchanger 4 in FIG. 1) on the side of the refrigerant circuit that is farther from the expansion mechanism 5. In addition, in the third embodiment, an intermediate heat exchanger is not essential. Even if an intermediate heat exchanger 7 is present, its location is not particularly limited. The other configurations of the third embodiment are the same as those of the first embodiment.

The arrangement of the main heat exchanger 45 and the auxiliary heat exchanger 47 in this embodiment is explained using the top view in Figure 10A and the cross-sectional view in Figure 10B.

As shown in FIG. 10A, the auxiliary heat exchanger 47 of this embodiment is disposed inside the housing 20 and inside the main heat exchanger 45, independent of the main heat exchanger 45. Here, "independent" means that the fins 50 of the main heat exchanger 45 and the fins (not shown) of the auxiliary heat exchanger 47 are not connected, and the main heat exchanger 45 and the auxiliary heat exchanger 47 have separate refrigerant inlets and outlets. In addition, a refrigerant collecting section may be further disposed between the main heat exchanger 45 and the auxiliary heat exchanger 47 in the refrigerant circuit. By disposing the refrigerant collecting section, the refrigerant is collected once, and the refrigerant temperature, etc. are homogenized.

As shown in FIG. 10B, the secondary heat exchanger 47 is positioned at a height more than half the height at which the main heat exchanger 45 is positioned.

This configuration is particularly effective when the heat source side heat exchanger is used as a radiator. That is, in a radiator in a refrigeration cycle using a _CO2 refrigerant, the refrigerant temperature is higher at the refrigerant inlet and lower near the outlet. That is, in this embodiment, the refrigerant temperature is high in the auxiliary heat exchanger 47 and slightly lower in the main heat exchanger 45. That is, in the auxiliary heat exchanger 47, there is a large temperature difference between the refrigerant and the air.

In the heat source unit 10 of this embodiment, the fan 40 is positioned above the main heat exchanger 45 and the auxiliary heat exchanger 47, and the wind speed increases the higher up the side of the heat exchanger 4.

The auxiliary heat exchanger 47 is located downstream of the main heat exchanger 45, but still ensures a sufficient temperature difference between the air and the refrigerant. The main heat exchanger is located on the windward side, so that a sufficient temperature difference between the air and the refrigerant can be ensured, and the amount of heat exchange can be increased.

In addition, because the auxiliary heat exchanger 47 is located at the top, the air volume is relatively large, allowing for a large amount of heat exchange.

Although the embodiments of the present disclosure 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 present disclosure as set forth in the claims.

Reference Signs List 1 Refrigeration device 2 Compressor 3 Four-way switching valve 4 Heat source side heat exchanger 5 Expansion mechanism 6 Use side heat exchanger 7 Intermediate heat exchanger 10 Heat source unit 20 Housing 30 Heat transfer tube 30a First heat transfer tube 30b Second heat transfer tube 31 First straight section 32 Second straight section 33 Turned section 35 Circular tube 350 U-shaped tube 40 Fan 45 Main heat exchanger 46, 47 Auxiliary heat exchanger 50 Fin

JP 2009-150641 A

Claims (10)

A heat source unit (10) of a refrigeration device (1) using a _CO2 refrigerant and performing heat exchange between the _CO2 refrigerant and another fluid,
A compressor (2) that performs two or more stages of compression;
a main heat exchanger (4, 45) for exchanging heat between the refrigerant and the fluid;
a secondary heat exchanger (7, 46, 47) that is arranged independently of the main heat exchanger and performs heat exchange with the fluid, the secondary heat exchanger being arranged upstream or downstream of the main heat exchanger in the flow of the fluid;
Equipped with
Heat source unit for refrigeration equipment. The auxiliary heat exchanger is an intermediate heat exchanger (7) that exchanges heat between the refrigerant and the fluid after the first stage compression by the compressor and before the final stage compression,
The intermediate heat exchanger is disposed upstream of the main heat exchanger in the flow of the fluid.
A heat source unit for a refrigeration apparatus according to claim 1. the fluid is air;
The heat source unit further comprises:
a fan (40) for blowing said air to said main heat exchanger;
a housing (20) that houses the compressor, the main heat exchanger, the fan, and the intermediate heat exchanger;
Equipped with
The fan draws in the air from a side surface of the housing and blows the air upward from a top surface of the housing.
A heat source unit for a refrigeration apparatus according to claim 2. The intermediate heat exchanger is disposed at a height above half the height of the main heat exchanger.
A heat source unit for a refrigeration apparatus according to claim 3. The heat source unit further comprises:
An expansion mechanism (5) for expanding a refrigerant,
The auxiliary heat exchanger (46) is connected between the main heat exchanger (45) and the expansion mechanism in a refrigerant circuit,
The auxiliary heat exchanger is disposed upstream of the main heat exchanger in the flow of the fluid.
A heat source unit for a refrigeration apparatus according to claim 1. the fluid is air;
The heat source unit further comprises:
a fan (40) for blowing said air to said main heat exchanger;
a housing (20) that houses the compressor, the main heat exchanger, the fan, and the auxiliary heat exchanger;
Equipped with
The fan draws in the air from a side surface of the housing and blows the air upward from a top surface of the housing.
A heat source unit for a refrigeration apparatus according to claim 5. The auxiliary heat exchanger is disposed at a height above half the height of the main heat exchanger.
A heat source unit for a refrigeration apparatus according to claim 6. The heat source unit further comprises:
An expansion mechanism (5) for expanding a refrigerant,
The auxiliary heat exchanger (46) is connected to a refrigerant inlet/outlet of the main heat exchanger, the refrigerant inlet/outlet being farther from the expansion mechanism in the refrigerant circuit,
The auxiliary heat exchanger is disposed downstream of the main heat exchanger in the flow of the fluid.
A heat source unit for a refrigeration apparatus according to claim 1. the fluid is air;
The heat source unit further comprises:
a fan (40) for blowing said air to said main heat exchanger;
a housing (20) that houses the compressor, the main heat exchanger, the fan, and the auxiliary heat exchanger;
Equipped with
The fan draws in the air from a side surface of the housing and blows the air upward from a top surface of the housing.
A heat source unit for a refrigeration apparatus according to claim 8. The auxiliary heat exchanger is disposed at a height above half the height of the main heat exchanger.
A heat source unit for a refrigeration apparatus according to claim 9.

Images