JP2005037054A - Heat exchanger for refrigerant cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger using a micro-tube, capable of remarkably improving the heat exchanging performance by smoothing the flow of the refrigerant in the heat exchanger. <P>SOLUTION: In this refrigerant cycle device wherein a refrigerant cycle is composed of a compressor 2, a gas cooler 10, a decompressor 4, an evaporator 5 and the like, the heat exchanger is used as the gas cooler 10 or the evaporator 5, and comprises the plurality of micro-tubes 20. A refrigerant passage 21 positioned at a lower part among the refrigerant passages of the micro-tubes 20 has a diameter larger than the refrigerant passages 21 positioned at an upper part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat exchanger for a refrigerant cycle device used as a gas cooler or an evaporator of a refrigerant cycle device in which a refrigerant cycle is configured from a compressor, a gas cooler, a decompression device, an evaporator, and the like.

In recent years, carbon dioxide (CO ₂ ) has been used as a refrigerant in an air conditioner equipped with a refrigerant cycle device such as a car air conditioner in order to cope with global environmental problems (see Patent Document 1). Since the CO ₂ refrigerant operates supercritically, heat transfer is likely to occur in the gas cooler of the refrigerant circuit. For this reason, the temperature change of a refrigerant | coolant is remarkable and in the fin and tube type heat exchanger corresponding to a condensed refrigerant | coolant, heat dissipation efficiency will fall for a pressure | voltage resistance. Therefore, it is conceivable to use a heat exchanger using a microtube. This microtube is constituted by a flat tube provided with a plurality of minute diameter refrigerant passages. And the some micro tube was prepared and the structure which connected the edge part of each micro tube with the header was taken. In this case, a microtube having the same diameter is used for the heat exchanger from the upstream side to the downstream side of the refrigerant passage.
JP 2001-263861 A (see pages 2 and 4).

  However, a conventional microtube type heat exchanger has a configuration in which a plurality of microtubes composed of flat tubes are arranged side by side at a predetermined interval to form a row, and the rows are arranged at a plurality of intervals. From the upstream side to the downstream side of the exchanger, microtubes having the same diameter refrigerant passage have been used. For this reason, the oil discharged together with the refrigerant from the compressor is accumulated in the refrigerant passage located below the microtube, and the pressure loss is increased to disturb the refrigerant flow. Therefore, if the diameters of all the refrigerant passages are increased, there is a problem that the heat exchange efficiency is lowered this time.

  The invention of claim 1 is a heat exchanger used as a gas cooler or an evaporator in a refrigerant cycle device in which a refrigerant cycle is configured from a compressor, a gas cooler, a decompression device, an evaporator, and the like, and includes a plurality of microtubes, Among the refrigerant passages of each microtube, the refrigerant passage located below is made larger in diameter than the refrigerant passage located above.

  The invention of claim 2 includes a header portion provided at both ends of each microtube, and the cross-sectional area of the communication passage in the header portion is 10 times or more the cross-sectional area of the refrigerant passage of the microtube. is there.

  The invention of claim 3 is a heat exchanger used as a gas cooler or an evaporator in a refrigerant cycle device in which a refrigerant cycle is configured from a compressor, a gas cooler, a decompression device, an evaporator, and the like, and includes a plurality of microtubes, The refrigerant passages of the respective microtubes have different diameters on the upstream side and the downstream side of the refrigerant partially or entirely.

  When the invention is used as a gas cooler, the diameter of the refrigerant passage of each microtube is increased on the upstream side of the refrigerant and decreased on the downstream side.

  According to a fifth aspect of the present invention, in the third aspect, when used as an evaporator, the diameter of the refrigerant passage of each microtube is reduced on the upstream side of the refrigerant and increased on the downstream side.

According to the first aspect of the present invention, in the heat exchanger used as a gas cooler or an evaporator, a plurality of microtubes are provided, and the refrigerant passage located below the refrigerant passage of each microtube is located above the refrigerant passage. Since the diameter is larger than the passage, even when the oil discharged from the compressor together with the refrigerant accumulates in the refrigerant passage below the microtube, the pressure loss due to the accumulated oil can be reduced. Thereby, it becomes possible to smoothly flow the refrigerant into the heat exchanger. Therefore, the pressure loss due to oil can be reduced while maintaining the heat exchange efficiency of the heat exchanger, and the heat exchange capacity can be greatly improved as a whole. In addition, it is possible to reduce the influence of the pressure loss due to the gas cooler, which is a characteristic of the CO ₂ cycle, on the decrease in the refrigerating capacity, and to improve the cycle efficiency.

  Further, the cross-sectional area of the communication path in the header portion provided at both ends of each microtube as in claim 2 is set to 10 times or more the cross-sectional area of the refrigerant path of the microtube, so that the refrigerant path positioned above is Since the gas passes and the oil passes through the refrigerant passage located below, pressure loss in the refrigerant passage located above can be prevented.

  According to the invention of claim 3, in the heat exchanger used as a gas cooler or an evaporator, the heat exchanger includes a plurality of microtubes, and the refrigerant passage of each microtube is partially or entirely on the upstream side and the downstream side of the refrigerant. Since different diameters are used, for example, when used as a gas cooler as in claim 4, the oil viscosity on the downstream side is reduced by using oil whose solubility changes, and the diameter of the refrigerant passage of each microtube Is reduced on the upstream side of the refrigerant and reduced on the downstream side, thereby reducing pressure loss on the inlet side of the gas cooler where high pressure gas flows in along with oil from the compressor, and allowing the refrigerant to flow smoothly on the inlet side of the gas cooler. it can. Thereby, it is possible to reduce pressure loss due to oil. Therefore, the heat exchange efficiency between the refrigerant and air in the gas cooler can be remarkably improved. Further, by reducing the diameter of the downstream refrigerant passage, durability can be easily handled, the thickness can be reduced, and the heat exchange efficiency can be improved.

  Further, as in claim 5, when the heat exchanger is used as an evaporator in which the temperature decreases on the downstream side and the refrigerant gas density increases, the diameter of the refrigerant passage of each microtube is reduced on the upstream side of the refrigerant, By increasing the size on the downstream side, the pressure loss in the refrigerant passage can be reduced. Thereby, it becomes possible to flow the refrigerant gas in the evaporator smoothly. Therefore, the heat exchange efficiency between the refrigerant and air in the evaporator can be remarkably improved.

  An object of this invention is to provide the heat exchanger using the microtube which flowed the refrigerant | coolant in a heat exchanger smoothly, and aimed at the significant improvement in heat exchange capability.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of a cooling device 1 according to an embodiment provided with a heat exchanger for a refrigerant cycle device of the present invention. In this figure, 1 is a cooling device used in a car air conditioner and the like, 2 is a two-stage compression type rotary compressor constituting the cooling device 1, and CO ₂ (carbon dioxide) is used as a refrigerant in this refrigerant circuit. Yes.

The rotary compressor 2 (corresponding to the compressor of the present invention) includes an electric element (not shown) in a sealed container 51 and first and second rotary compression elements 52 and 53 driven by the electric element. The internal intermediate pressure type multi-stage (two-stage) compression rotary compressor. Then, the refrigerant gas (CO ₂ ) sucked from the refrigerant suction pipe 2B is compressed by the first rotary compression element 52, and the compressed refrigerant is discharged into the sealed container 51 once. The intermediate pressure refrigerant gas in the sealed container 51 is sucked into the second rotary compression element 53, compressed, and discharged from the refrigerant discharge pipe 2A.

  A gas cooler 10 as a heat exchanger for the refrigerant cycle device of the present invention is connected to the refrigerant discharge pipe 2A of the rotary compressor 2, and an expansion valve (the present invention) is connected to a pipe 4A provided on the outlet side of the gas cooler 10. The evaporator 5 is connected via a pressure reducing device 4. The outlet side of the evaporator 5 is connected to the refrigerant suction pipe 2B of the rotary compressor 2 via the accumulator 6, thereby forming an annular refrigerant circuit. Reference numeral 54 denotes an intermediate heat exchanger for exchanging heat between the refrigerant exiting the gas cooler 10 and the refrigerant exiting the evaporator 5.

Then, the high-temperature and high-pressure gas refrigerant (CO ₂ ) compressed in two stages by the first and second rotary compression elements 52 and 53 of the rotary compressor 2 as described above exchanges heat with the air passed through the gas cooler 10. And dissipate heat. In this state, the refrigerant does not condense, is further cooled by the intermediate heat exchanger 54, is liquefied in the process of being expanded after flowing into the expansion valve 4 and being throttled. Then, it flows into the evaporator 5, where it evaporates and vaporizes, thereby taking heat away from the surroundings and exerting a cooling effect. Using this cooling effect, air in a vehicle compartment (not shown) is cooled and air-conditioned.

  The refrigerant leaving the evaporator 5 takes heat from the refrigerant from the gas cooler 10 in the intermediate heat exchanger 54, and then flows into the accumulator 6, where it is separated into gas and liquid, and only the gas refrigerant is discharged from the refrigerant suction pipe 2B to the rotary compressor 2. The transcritical refrigerant cycle sucked into the is repeated.

  The gas cooler 10 is composed of a pair of left and right header portions 11, 12 arranged in parallel to each other and a plurality of microtubes 20... Mounted between the header portions 11, 12. In this case, both header portions 11 and 12 have the same shape, and both header portions 11 and 12 are connected to both ends of each microtube 20.

  The microtube 20 is a flat tube made of a metal such as aluminum and having a substantially oval or oval cross section. Inside the microtube 20, a plurality of refrigerant passages 21 are formed that extend from one end to the other end, and are formed by small diameter cross-sectional oblong holes through which the refrigerant flows. The plurality of refrigerant passages 21 are formed so as to extend in the longitudinal direction of the microtube 20, and the refrigerant passages 21 are provided in parallel to each other. In the embodiment, the refrigerant passages 21 are provided in eight rows in the microtube 20. In addition, the number of the refrigerant paths 21 in the microtube 20 is not restricted to an Example.

  The gas cooler 10 is provided with a plurality of microtubes 20 in the left-right direction, and these microtubes 20 are provided in a plurality of stages (only three stages are shown in the drawing) (FIG. 3). In addition, the microtube 20 is arranged so that the refrigerant passages 21 are arranged in the vertical direction, and the refrigerant passage 21L positioned below as shown in FIG. 4 has a larger diameter than the refrigerant passage 21S positioned above it. . That is, in the embodiment, the six rows from the top are the small-diameter refrigerant passages 21S... And the bottom two rows are the large-diameter refrigerant passages 21L and 21L.

  A plurality of connection holes 13 are formed in both the header portions 11 and 12, and each connection hole 13... Is substantially in the shape of the end of the microtube 20 so that the end of the microtube 20 can be inserted. It is formed in the shape of a matched ellipse or ellipse, and is open on one side of the header portions 11 and 12 (on the side of the opposite surfaces). In addition, the inner dimensions of these connection holes 13... Are reduced as they go from the opening on one side to the other side of the header portions 11 and 12.

  In the embodiment, the connection holes 13 are formed with predetermined intervals of three rows, and four, three, and four connection holes 13 are formed with predetermined intervals in each row. In addition, a plurality of rows (three rows in the embodiment) of communication passages 14 are provided in the header portions 11 and 12, and each of the communication passages 14... Communicates with the depths of the connection holes 13. (FIGS. 2 and 3). With the communication passage 14, the connection holes 13... Constituting each row are communicated with each other in each row.

  The communication path 14 does not communicate the row of connection holes 13 with each other. Further, the cross-sectional area of the communication passage 14 is set to be 10 times or more the cross-sectional area of the large-diameter refrigerant passage 21L of the microtube 20. Reference numeral 15 denotes a closing portion for closing the communication passage 14 provided in the header portion 11, and 16 is a bend pipe for connecting the central communication passage 14 and the communication passage 14 adjacent to the downstream side of the refrigerant.

  The refrigerant discharge pipe 2A is connected from the outside of the closing portion 15 to the refrigerant upstream communication passage 14 provided in the header 11 on one side, and the refrigerant upstream communication passage 14 and the refrigerant discharge pipe 2A are connected to each other. Communicate with each other. A bend pipe 17 is attached to the header portion 12 on the other side from the outside of the closed portion (not shown). The bend pipe 17 is connected to a communication path on the upstream side of the refrigerant (not shown) provided in the header portion 12 on the other side, To communicate with the communication path. Further, the pipe 4 </ b> A is connected to a refrigerant downstream communication path provided in the header portion 12 on the other side, that is, a communication path on the outlet side of the gas cooler 10.

  On the other hand, the microtubes 20 extending between the header portions 11 and 12 are arranged at predetermined intervals in three rows corresponding to the connection holes 13..., And each of the four tubes is arranged in parallel at predetermined intervals. , Three and four microtubes 20. Then, both ends of each microtube 20... Are inserted into the connection holes 13.

  In this case, the microtubes 20 arranged in a plurality of rows (three rows) have a predetermined interval between the microtubes 20 in the one row adjacent to each other. Then, they are arranged so as to enter a predetermined dimension (the connection holes 13 are also arranged in the same manner).

  Then, the high-temperature refrigerant discharged from the rotary compressor 2 to the refrigerant discharge pipe 2A enters the upstream first row communication passage 14 in the header portion 11 on one side, where the microtubes 20. The refrigerant flows into the refrigerant passages 21. And it merges in the 1st line communication path 14 provided in the header part 12 of the other side, enters into the 2nd line communication path 14 through the bend piping 17, and each microtube 20 which is divided there and forms the 2nd line. .. flows into the refrigerant passage 21.

  Next, it enters the second row of communication passages 14 in the header portion 11 on one side, merges there and flows into the third row of communication passages 14 from the bend pipe 16, and then divides there to form the third row of micros. After flowing into the refrigerant passages 21... Of the tubes 20..., They enter the communication passage 14 in the third row of the header portion 12 on the other side, merge there and flow out to the pipe 4 A connected to the header portion 12.

That is, the first row of microtubes 20..., The second row of microtubes 20..., And the third row so that adjacent rows of microtubes 20. Are connected in series in the order of the microtubes 20. As a result, the refrigerant flows in series from the first row to the third row in the microtubes 20 forming each row of the gas cooler 10 (the refrigerant is parallel to the microtubes 20 in the row). Flowing). As the compressor operating oil, PAG, POE, PVE, mineral oil or the like having a characteristic of dissolving CO ₂ as the temperature is lowered at a temperature higher than normal temperature is used.

Next, the operation of the cooling device 1 with the above configuration will be described. When an electric element (not shown) of the rotary compressor 2 is energized and thereby the first and second rotary compression elements 52 and 53 are driven, the rotary compressor 2 generates a high-temperature and high-pressure refrigerant (CO ₂ ) compressed in two stages. Is discharged into the refrigerant discharge pipe 2A. The refrigerant discharged to the refrigerant discharge pipe 2A flows into the gas cooler 10 and flows through the microtubes 20 as described above.

  In this case, in the case of the multi-stage compression rotary compressor 10 as in the embodiment, the oil discharge amount from the second rotary compression element 53 increases. The oil mixed in the high-temperature and high-pressure refrigerant that has flowed into the micro tubes 20 of the gas cooler 10 tends to accumulate in the lower refrigerant passage 21L of the refrigerant passage 21 of the micro tube 20 of the gas cooler 10, but in the present invention, Since the refrigerant passages 21L and 21L have a larger diameter than the upper refrigerant passages 21S..., The pressure loss is reduced even if oil accumulates in the lower refrigerant passages 21L and 21L. Moreover, since the cross-sectional area of the communication path 14 in the header parts 11 and 12 is 10 times or more the cross-sectional area of the refrigerant path 21L of the microtube 20, oil separation is performed in the communication path 14 and Since gas passes through the refrigerant passage 21S and oil passes through the lower refrigerant passage 21L, pressure loss in the upper refrigerant passage 21S can be prevented. As a result, the refrigerant in the gas state passes smoothly through the microtubes 20 through the gas cooler 10. On the other hand, since the upper refrigerant passage 21S has a small diameter, heat exchange efficiency is also ensured. Then, it finally flows out to the pipe 4A. The gas cooler 10 is ventilated by a blower (not shown) in the direction of the white arrow in FIG.

  The wind sent from the blower passes between each microtube 20... And exchanges heat with the refrigerant flowing through the refrigerant passage 21... Of the microtube 20, thereby cooling the refrigerant and conversely warming the air. . In this case, since the draft is opposed to the flow of the refrigerant flowing in the microtube 20 of the gas cooler 10, the refrigerant in the gas cooler 10 can be cooled with high efficiency.

  The refrigerant that has exited the gas cooler 10 is further cooled by the intermediate heat exchanger 54 as described above, and after flowing into the expansion valve 4 and being throttled, it is liquefied in the process of expansion. Then, it flows into the evaporator 5, where it evaporates and vaporizes, thereby taking heat away from the surroundings and exerting a cooling effect. Using this cooling effect, air in a vehicle compartment (not shown) is cooled and air-conditioned.

  The refrigerant leaving the evaporator 5 takes heat from the refrigerant from the gas cooler 10 in the intermediate heat exchanger 54, and then flows into the accumulator 6, where it is separated into gas and liquid, and only the gas refrigerant is discharged from the refrigerant suction pipe 2B to the rotary compressor 2. Is what is sucked into.

  Next, FIG. 5 shows a gas cooler 10 according to another embodiment of the present invention. In this case, the microtube 20 is provided so that the refrigerant passages 21. That is, the gas cooler 10 has horizontal microtubes 20 arranged vertically. In this case, the refrigerant passages 21... Of the microtubes 20 positioned below are made large-diameter refrigerant passages 21L.

  In the embodiment, the present invention has been described by taking the gas cooler 10 as an example. However, the present invention is not limited to this, and the evaporator 5 also has the same microtube structure as that of the gas cooler 10 described above, whereby the same effect can be obtained. .

  Further, instead of or in addition to the above configuration, in the case of the gas cooler 10, a part or all of the refrigerant passages 21... On the upstream side of the refrigerant are connected to the micro tube 20 on the downstream side. The diameter may be larger than that of the refrigerant passage 21. In such a case, the pressure loss on the inlet side of the gas cooler 10 where the high-pressure gas flows together with oil from the rotary compressor 2 can be reduced, and the refrigerant in the gas cooler 10 can flow smoothly.

  On the other hand, in the case of the evaporator 5, a part or all of the refrigerant passages 21... On the upstream side of the refrigerant may have a smaller diameter than the refrigerant passages 21. . Even in such a case, the pressure loss in the refrigerant passage 21 of the microtube 20 of the evaporator 5 where the gas density of the refrigerant becomes higher on the downstream side can be reduced. Thereby, the refrigerant gas in the evaporator 5 can flow smoothly, and the heat exchange efficiency between the refrigerant and the air in the evaporator 5 can be remarkably improved.

In the embodiment, the heat exchanger (gas cooler 10 or evaporator 5) of the present invention is applied to the cooling device 1 used in a car air conditioner or the like. However, the present invention is not limited to this, and the refrigerant has a high thermal conductivity and a significant temperature change. The present invention is also effective when used in various refrigerant circuit devices in which a refrigerant (such as CO _{2 in the} embodiment) is used.

It is a refrigerant circuit figure of the cooling device of the Example provided with the heat exchanger for refrigerant cycle devices of the present invention. It is an expansion perspective view of the header part of the gas cooler as an Example of the heat exchanger of this invention. It is a front view of the header part of the gas cooler of FIG. It is an enlarged view of the microtube of the gas cooler of FIG. It is a figure which shows the other Example of the microtube of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Rotary compressor 2A Refrigerant discharge pipe 2B Refrigerant suction pipe 4 Expansion valve 4A Piping 5 Evaporator (heat exchanger)
6 Accumulator 10 Gas cooler (heat exchanger)
20 Microtube 21, 21L, 21S Refrigerant passage

Claims (5)

A heat exchanger used as the gas cooler or evaporator in a refrigerant cycle device in which a refrigerant cycle is configured from a compressor, a gas cooler, a decompression device, an evaporator, and the like,
A heat exchanger for a refrigerant cycle device comprising a plurality of microtubes, wherein a refrigerant passage located below among refrigerant passages of each microtube has a larger diameter than a refrigerant passage located above.   The header part provided in the both ends of each said microtube is provided, The cross-sectional area of the communicating path in this header part was made into 10 times or more of the cross-sectional area of the refrigerant path of the said microtube, The feature of Claim 1 characterized by the above-mentioned. Heat exchanger for refrigerant cycle equipment. A heat exchanger used as the gas cooler or evaporator in a refrigerant cycle device in which a refrigerant cycle is configured from a compressor, a gas cooler, a decompression device, an evaporator, and the like,
A heat exchanger for a refrigerant cycle device, comprising a plurality of microtubes, wherein the refrigerant passages of the microtubes have different diameters on the upstream side and the downstream side of the refrigerant partially or entirely.   4. The heat exchanger for a refrigerant cycle device according to claim 3, wherein when used as the gas cooler, the diameter of the refrigerant passage of each microtube is increased on the upstream side of the refrigerant and decreased on the downstream side.   4. The heat exchanger for a refrigerant cycle device according to claim 3, wherein, when used as the evaporator, the diameter of the refrigerant passage of each microtube is small on the upstream side of the refrigerant and large on the downstream side.

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