JP5403039B2 - Air conditioner - Google Patents

Description

  The present invention relates to a double-pipe heat exchanger and an air conditioner including the same.

  In an air conditioner, a refrigerant circuit including a supercooling heat exchanger that supercools high-pressure liquid refrigerant before flowing into an expansion valve is known. Moreover, as this supercooling heat exchanger, as disclosed in the following Patent Document 1, an outer tube for flowing a high-pressure liquid refrigerant and a low-pressure gas-liquid two-phase refrigerant obtained by depressurizing the high-pressure liquid refrigerant are used. There is a double pipe type with an inner pipe to be flowed. Specifically, this Patent Document 1 discloses a vertical pipe-shaped double pipe heat exchanger arranged in the vertical direction and an inverted U-shaped double pipe heat exchanger.

JP 2003-75026 A

  The vertical pipe-shaped double-pipe heat exchanger needs to secure a wide arrangement space in the vertical direction in the casing of the outdoor unit in the air conditioner, and refrigerant piping is connected to the upper end and the lower end respectively. Therefore, when connecting the refrigerant pipes, there is a disadvantage that a process of turning the double pipe heat exchanger upside down is required, and the work becomes complicated.

  On the other hand, the inverted U-shaped double tube heat exchanger can be arranged compactly in the vertical direction, and both ends are arranged on the same side (lower side). There is an advantage that the connection work becomes easy. However, the gas-liquid two-phase refrigerant that has flowed in from one end (inlet side end) of the inner tube flows upward, then flows downward through a U-shaped curved portion, and the other end (outlet side) Therefore, if the gas-liquid two-phase refrigerant is not sufficiently evaporated inside the inner pipe, the liquid portion (liquid refrigerant) contained in the gas-liquid two-phase refrigerant exceeds the curved portion. If this happens, it will flow downward in the inner pipe and will likely flow out of the outlet end, and may flow into the compressor. Such a phenomenon is called a “liquid back phenomenon” and is not preferable because it causes a reduction in the performance of the compressor.

The present invention has been made in view of such a situation, and while being able to be compactly configured, the liquid refrigerant contained in the gas-liquid two-phase refrigerant is suppressed from flowing out of the inner pipe, and the liquid An object of the present invention is to provide an air conditioner including a double-pipe heat exchanger that can prevent the occurrence of a back phenomenon.

The air conditioner of the present invention includes a compressor, a condenser that condenses the high-pressure gas refrigerant compressed by the compressor, a decompression mechanism that decompresses the condensed high-pressure liquid refrigerant, and evaporates the decompressed low-pressure refrigerant. An evaporator, and a double-tube heat exchanger that supercools the high-pressure liquid refrigerant condensed by the condenser before depressurization by the decompression mechanism, and the double-tube heat exchanger includes a high-pressure liquid An inner pipe having an outer tube for flowing the refrigerant, an inlet side end portion for introducing a low-pressure gas-liquid two-phase refrigerant obtained by depressurizing the high pressure liquid refrigerant, and an outlet side end portion connected to the suction side of the compressor A pipe, and the outer pipe and the inner pipe include a plurality of vertical pipes arranged in the vertical direction and a curved pipe connecting ends of the plurality of vertical pipes, and the outlet of the inner pipe A side end is provided at an upper end of one vertical pipe, and an inlet side end of the inner pipe is an upper end of another vertical pipe. Provided, the curved pipe connected to the lower end portions of a plurality of vertical tubes in the double-pipe heat exchanger, that is supported via a support member on the bottom frame of the casing in the air conditioner It is characterized by.

According to this configuration, the gas-liquid two-phase refrigerant that has flowed from the inlet side end of the inner pipe evaporates by exchanging heat with the high-pressure liquid refrigerant that flows through the outer pipe while flowing through the inner pipe, and becomes a gas refrigerant. Outflow from the outlet end of the tube. At this time, since the outlet side end portion of the inner pipe is formed at the upper end portion of one vertical pipe, even if the gas-liquid two-phase refrigerant is not sufficiently evaporated and the liquid portion (liquid refrigerant) remains. Since this liquid portion is unlikely to rise in the inner tube of one vertical tube, it is difficult for the liquid portion to flow out from the outlet side end. Therefore, it is possible to prevent a “liquid back phenomenon” in which liquid refrigerant is generated in the compressor.
In addition, since both the inlet side end and the outlet side end of the inner pipe are provided at the upper end of the vertical pipe, the refrigerant pipe can be connected without inverting the double pipe heat exchanger. Connection work can be performed easily.
Further, since the curved pipe connected to the lower ends of the plurality of vertical pipes in the double pipe heat exchanger is supported on the bottom frame of the casing in the air conditioner via a support member, it is relatively strong. Therefore, the double-pipe heat exchanger can be stably supported in the portion of the bent pipe where the height is high.

In the above SL configuration, the support member is made of rubber or synthetic resin, on the upper surface, it is preferable that fitting concave portion for fitting the curved pipe is formed.
Moreover, it is preferable that the two vertical pipes are provided, and the lower ends of the vertical pipes are connected to each other by the curved pipe.
With such a configuration, the double-pipe heat exchanger can be configured simply, and the pressure loss of the refrigerant can be reduced by reducing the number of curved pipe portions.

  According to the present invention, the liquid refrigerant contained in the gas-liquid two-phase refrigerant can be prevented from flowing out of the inner pipe, and the occurrence of the liquid back phenomenon can be prevented while being compact.

It is a schematic diagram which shows the refrigerant circuit of the air conditioning apparatus which concerns on the 1st Embodiment of this invention. It is the schematic of the double pipe | tube type heat exchanger provided in the refrigerant circuit of the air conditioning apparatus shown by FIG. It is the schematic which shows the modification of the double tube type heat exchanger which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the modification of the refrigerant circuit of an air conditioning apparatus.

Drawing 1 is a mimetic diagram showing the refrigerant circuit of the air harmony device which has the outdoor unit concerning a 1st embodiment of the present invention.
The air conditioner 1 is a multi-type air conditioner for buildings, for example, and is a refrigerant circuit so that a plurality of indoor units 3 are connected in parallel to one or a plurality of outdoor units 2 and refrigerant can flow. 10 is formed.

  The outdoor unit 2 is provided with a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, an outdoor expansion valve 14, a supercooling heat exchanger 31, and the like, and these are connected by a refrigerant pipe to thereby form a refrigerant circuit. Is configured. The outdoor unit 2 is provided with a blower fan 23. The indoor unit 3 is provided with an indoor expansion valve 15, an indoor heat exchanger 16, and the like. The four-way switching valve 12 and the indoor heat exchanger 16 are connected by a gas side refrigerant communication pipe 17a, and the outdoor expansion valve 14 and the indoor expansion valve 15 are connected by a liquid side refrigerant communication pipe 17b. A gas side shut-off valve 18 and a liquid side shut-off valve 19 are provided at a terminal portion of the internal refrigerant circuit of the outdoor unit 2. The gas side closing valve 18 is arranged on the four-way switching valve 12 side, and the liquid side closing valve 19 is arranged on the outdoor expansion valve 14 side. A gas side refrigerant communication pipe 17 a is connected to the gas side shutoff valve 18, and a liquid side refrigerant communication pipe 17 b is connected to the liquid side shutoff valve 19.

  In the air conditioner 1 having the above-described configuration, when the cooling operation is performed, the four-way switching valve 12 is held in a state indicated by a solid line in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger (condenser) 13 through the four-way switching valve 12 and exchanges heat with outdoor air by the operation of the blower fan 23 to condense and liquefy. To do. The liquefied refrigerant passes through the fully-expanded outdoor expansion valve 14 and flows into each indoor unit 3 through the liquid side refrigerant communication pipe 17b. In the indoor unit 3, the refrigerant is depressurized to a predetermined low pressure by an indoor expansion valve (decompression mechanism) 15, and is further evaporated by exchanging heat with indoor air in an indoor heat exchanger (evaporator) 16. The room air cooled by the evaporation of the refrigerant is blown into the room by an indoor fan (not shown) to cool the room. The refrigerant evaporated in the indoor heat exchanger 16 returns to the outdoor unit 2 through the gas-side refrigerant communication pipe 17a, and is sucked into the compressor 11 through the four-way switching valve 12.

  On the other hand, when the heating operation is performed, the four-way switching valve 12 is held in a state indicated by a broken line in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger (condenser) 16 of each indoor unit 3 through the four-way switching valve 12, and heat-condenses with indoor air to condense and liquefy. . The indoor air heated by the condensation of the refrigerant is blown into the room by an indoor fan to heat the room. The refrigerant liquefied in the indoor heat exchanger 16 returns from the fully opened indoor expansion valve 15 to the outdoor unit 2 through the liquid side refrigerant communication pipe 17b. The refrigerant returned to the outdoor unit 2 is depressurized to a predetermined low pressure by the outdoor expansion valve (decompression mechanism) 14 and further evaporated by exchanging heat with outdoor air by the outdoor heat exchanger (evaporator) 13. Then, the refrigerant evaporated in the outdoor heat exchanger 13 is sucked into the compressor 11 through the four-way switching valve 12.

The supercooling heat exchanger 31 of the present embodiment is for supercooling the high-pressure liquid refrigerant that has flowed out of the outdoor heat exchanger 13 before the pressure is reduced by the indoor expansion valve 15 during the cooling operation as described above. used. In the present embodiment, the supercooling heat exchanger 31 is provided in a refrigerant pipe (referred to herein as the main refrigerant pipe 25) between the outdoor expansion valve 14 and the liquid side shut-off valve 19.
Further, the refrigerant circuit branches a part of the refrigerant (high-pressure liquid refrigerant) condensed in the outdoor heat exchanger 13 from the main refrigerant pipe 25 and supplies the cooling refrigerant as a cooling source to the supercooling heat exchanger 31. Thereafter, a bypass refrigerant circuit 26 is provided to return the cooling refrigerant to the suction side of the compressor 11. Specifically, the bypass refrigerant circuit 26 branches the refrigerant from the main refrigerant pipe 25 between the outdoor expansion valve 14 and the supercooling heat exchanger 31 and is connected to the cooling refrigerant inlet in the supercooling heat exchanger 31. It has a branch pipe 27 and a junction pipe 28 that joins the pipe from the outlet of the cooling refrigerant in the supercooling heat exchanger 31 to the suction side of the compressor 11.

  The branch pipe 27 is provided with a bypass expansion valve 29 that depressurizes the refrigerant. The bypass expansion valve 29 is composed of an electric valve or the like, and depressurizes the high-pressure liquid refrigerant flowing through the branch pipe 27 to form a low-pressure gas-liquid two-phase refrigerant. The high-pressure liquid refrigerant flowing from the outdoor heat exchanger 13 toward the indoor expansion valve 15 is supercooled by the low-pressure gas-liquid two-phase refrigerant in the supercooling heat exchanger 31. The liquid part (liquid refrigerant) contained in the gas-liquid two-phase refrigerant evaporates by heat exchange with the high-pressure liquid refrigerant, and is sucked into the compressor 11 as a gas refrigerant.

  FIG. 2 is a schematic view of a supercooling heat exchanger (double tube heat exchanger) provided in the refrigerant circuit of the air conditioner shown in FIG. The supercooling heat exchanger 31 of the present embodiment is a double tube heat exchanger. That is, as shown in FIGS. 1 and 2, the supercooling heat exchanger 31 is connected to the main refrigerant pipe 25 of the refrigerant circuit, and is an outer pipe through which the high-temperature and high-pressure liquid refrigerant flowing out of the outdoor heat exchanger 13 flows. 32 and an inner pipe 33 that is connected to the bypass refrigerant circuit 26 and flows the cooling refrigerant decompressed by the bypass expansion valve 29. More specifically, the inner pipe 33 has one end (inlet side end) 33A connected to the branch pipe 27 and the other end (outlet side end) 33B connected to the merging pipe 28. The high-pressure liquid refrigerant flowing in the outer pipe 32 and the gas-liquid two-phase refrigerant flowing in the inner pipe 33 are heat-exchanged with each other, whereby the high-pressure liquid refrigerant is supercooled, and the gas-liquid two-phase refrigerant is the liquid portion. Evaporates into a gas refrigerant.

  The supercooling heat exchanger 31 is formed in a U-shaped curved structure. Specifically, the supercooling heat exchanger 31 includes two vertical pipes 34A and 34B and a curved pipe 35 that connects the ends of the two vertical pipes 34A and 34B. The curved pipe 35 connects the lower ends of the two vertical pipes 34A and 34B. Accordingly, the refrigerant inlet side end portions 32A and 33A and the outlet side end portions 32B and 33B are provided at the upper ends of the two vertical tubes 34A and 34B.

  The gas-liquid two-phase cooling refrigerant depressurized by the bypass expansion valve 29 flows into the inner pipe 33 of the supercooling heat exchanger 31 from the inlet side end portion 33 </ b> A and flows through the outer pipe 32 in the process of flowing through the inner pipe 33. Heat exchange with the high-pressure liquid refrigerant becomes a gas refrigerant and flows out from the outlet side end portion 33B. However, when the liquid part of the gas-liquid two-phase refrigerant is not completely evaporated by heat exchange with the high-pressure liquid refrigerant, if the liquid part flows out from the outlet side end 33B, the liquid is sucked into the compressor 11 and liquid A back phenomenon occurs, causing the performance of the compressor 11 to deteriorate.

  In the present embodiment, since the outlet side end portion 33B of the inner tube 33 is provided at the upper end portion of the vertical tube 34B, even if the liquid portion of the gas-liquid two-phase refrigerant remains without being evaporated, It is difficult to rise toward the outlet side end portion 33B, and it is difficult to flow out from the end portion 33B. Therefore, the liquid back phenomenon to the compressor 11 can be suppressed. The liquid part of the gas-liquid two-phase refrigerant exchanges heat with the high-pressure liquid refrigerant in the outer pipe 32 while remaining in the curved pipe 35, and eventually becomes a gas refrigerant from the outlet side end portion 33B. Leaked. On the other hand, the two vertical pipes 34A and 34B are connected by a curved pipe 35 that does not have a horizontal portion, so that the gas-liquid two-phase refrigerant drift between the two vertical pipes 34A and 34B (liquid portion and gas). The vertical separation of the portion) can be suppressed as much as possible.

  Further, the inlet side end portion 32A and the outlet side end portion 32B of the outer tube 32 and the inlet side end portion 33A and the outlet side end portion 33B of the inner tube 33 in the supercooling heat exchanger 31 are all the same in the vertical direction. Since it is provided on the side (upper side), the refrigerant pipes can be connected to these without turning the supercooling heat exchanger 31 upside down. Therefore, the connection work of the refrigerant pipe to the supercooling heat exchanger 31 can be performed with good workability.

  The supercooling heat exchanger 31 is attached to the bottom frame 43 in the casing of the outdoor unit 2 via the support member 40. The support member 40 is made of rubber, synthetic resin, or the like, and is fixed to the bottom frame 43 by a fixture 42 made up of bolts and nuts. A fitting recess 41 that is recessed in a curved shape is formed on the upper surface of the support member 40. The subcooling heat exchanger 31 is supported by the support member 40 by fitting the bent tube 35 into the fitting recess 41 and fixing the support member 40 and the bent tube 35 with a fastening band or the like. Since the strength of the subcooling heat exchanger 31 is relatively high in the bent pipe 35, the subcooling heat exchanger 31 can be stably supported by the support member 40.

FIG. 3 is a schematic view showing a supercooling heat exchanger (double tube heat exchanger) according to the second embodiment.
The supercooling heat exchanger 31 shown in FIG. 3 includes four vertical tubes 34A to 34D and three curved tubes 35A to 35C. And the edge parts of adjacent vertical pipe 34A-34D are connected by the curved pipes 35A-35C, respectively, and are formed in the substantially W shape as a whole. Further, the inlet side end portions 32A and 33A and the outlet side end portions 32B and 33B of the outer tube 32 and the inner tube 33 are provided at the upper ends of the vertical tubes 34A and 34D. Further, the bent pipes 35 </ b> A and 35 </ b> C arranged on the lower side of the supercooling heat exchanger 31 are supported by the bottom frame 43 of the casing via the support member 40. Therefore, the supercooling heat exchanger 31 of the present embodiment has the same effects as the supercooling heat exchanger 31 shown in FIG. Furthermore, the supercooling heat exchanger 31 of the present embodiment can be configured more compactly in the vertical direction when the pipe length is the same as that of the supercooling heat exchanger 31 of the first embodiment. It becomes possible. However, in the present embodiment, the pressure loss of the refrigerant is likely to occur as much as the number of the curved pipes 35A to 35C increases, and therefore the first embodiment is more advantageous in this respect.

The present invention is not limited to the above-described embodiments, and can be appropriately changed within the scope of the invention described in the claims.
For example, the supercooling heat exchanger (double tube heat exchanger) 31 of the present invention can also be applied to the refrigerant circuit shown in FIG. In this refrigerant circuit, the supercooling heat exchanger 31 is a high-pressure liquid refrigerant that flows out from the outdoor heat exchanger 13 and a gas-liquid two-phase refrigerant that is decompressed by the indoor expansion valve 15 and partially evaporated in the indoor heat exchanger 16. It is comprised so that heat exchange may be performed between. In this refrigerant circuit, the supercooling heat exchanger 31 can suitably supercool the high-pressure liquid refrigerant even during the heating operation.

  In the supercooling heat exchanger 31 shown in FIG. 3, a plurality of vertical tubes 34A to 34D and curved tubes 35A to 35C are arranged in a straight line in a plan view. It may be arranged in a letter shape. In addition, the supercooling heat exchanger 31 may include six or more vertical tubes (5 or more curved tubes).

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 10 Refrigerant circuit 11 Compressor 12 Four-way switching valve 13 Outdoor heat exchanger 14 Outdoor expansion valve 15 Indoor expansion valve 16 Indoor heat exchanger 31 Supercooling heat exchanger (double-tube heat exchanger )
32 Outer pipe 33 Inner pipe 33A Inlet side end 33B Outlet side end 34A to 34D Vertical pipe 35 Curved pipe 35A to 35C Curved pipe 40 Support member 43 Bottom frame

Claims (3)

A compressor (11), a condenser (13, 16) for condensing the high-pressure gas refrigerant compressed by the compressor (11), a decompression mechanism (15, 14) for depressurizing the condensed high-pressure liquid refrigerant, The evaporator (16, 13) that evaporates the decompressed low-pressure refrigerant and the high-pressure liquid refrigerant condensed by the condenser (13, 16) are supercooled before being decompressed by the decompression mechanism (15, 14). A heavy pipe heat exchanger (31),
The double-pipe heat exchanger (31) includes an outer pipe (32) for flowing the high-pressure liquid refrigerant, and an inlet side end for flowing in a low-pressure gas-liquid two-phase refrigerant obtained by depressurizing the high-pressure liquid refrigerant. part (33A), and an inner tube having an outlet side end portion (33B) which is connected to the suction side of the compressor (11) and (33), provided with,
The outer pipe (32) and the inner pipe (33) include a plurality of vertical pipes (34A, 34B, 34C, 34D) and a plurality of vertical pipes (34A, 34B, 34C, 34D) arranged in the vertical direction. Consisting of curved pipes (35, 35A, 35B, 35C) connecting the ends of
The outlet side end (33B) of the inner pipe (33) is provided at the upper end of one vertical pipe (34B, 34D),
The inlet side end (33A) of the inner pipe (33) is provided at the upper end of the other vertical pipe (34A),
The curved pipe (35) connected to the lower ends of a plurality of vertical pipes (34A, 34B, 34C, 34D) in the double pipe heat exchanger (31) is a bottom frame of a casing in the air conditioner ( 43) An air conditioner supported on a support member (40) . The air conditioner according to claim 1, wherein the support member (40) is made of rubber or synthetic resin, and has a fitting recess (41) into which the bent pipe (35) is fitted. . The air according to claim 1 or 2, wherein the two vertical tubes (34A, 34B) are provided, and lower ends of the vertical tubes (34A, 34B) are connected to each other by the curved tube (35). Harmony device.

Images