Patent Application
20140326019
The present invention relates to a double-pipe heat exchanger and an air conditioner using same.
There is a known refrigerant circuit including a supercooling heat exchanger for supercooling a high pressure liquid refrigerant before flowing into an expansion valve in an air conditioner. As this supercooling heat exchanger, as disclosed in Patent Literature 1 below, there is a double-pipe heat exchanger including an outer pipe through which a high pressure liquid refrigerant flows, and an inner pipe through which a low pressure gas-liquid two-phase refrigerant obtained by reducing pressure of the high pressure liquid refrigerant flows. Specifically, Patent Literature 1 discloses a double-pipe heat exchanger of a vertical pipe shape arranged in the up and down direction, and a double-pipe heat exchanger of an inverted U shape.
Patent Literature 1: Japanese Unexamined Patent Publication No. 2003-75026
In the double-pipe heat exchanger of the vertical pipe shape, there is a need for ensuring an arrangement space which is wide in the up and down direction in a casing of an outdoor unit in an air conditioner, and a refrigerant pipe has to be connected to each of an upper end and a lower end of the double-pipe heat exchanger. Thus, at the time of a task of connecting this refrigerant pipe, there is a need for a step of inverting the double-pipe heat exchanger upside down. Thus, there is a disadvantage that the task becomes troublesome.
Meanwhile, the double-pipe heat exchanger of the inverted U shape can be arranged compactly in the up and down direction, and both ends are arranged on the same side (lower side). Thus, there is an advantage that a task of connecting a refrigerant pipe is easily performed. However, a gas-liquid two-phase refrigerant flowing in from one end (inlet side end) of an inner pipe flows upward and then flows downward through a U shape curved portion, and flows out from the other end (outlet side end). Thus, in a case where the gas-liquid two-phase refrigerant is not sufficiently evaporated inside the inner pipe, and when a liquid component (liquid refrigerant) contained in the gas-liquid two-phase refrigerant gets over the curved portion, there is a possibility that the liquid component flows downward in the inner pipe and easily flows out from the outlet side end, so as to flow into a compressor. Such a phenomenon is called as a “liquid-back phenomenon” which unfavorably causes a decrease in a performance of the compressor.
The present invention is achieved in consideration with the situation described above, and an object thereof is to provide a double-pipe heat exchanger and an air conditioner capable of achieving a compact configuration, and suppressing a liquid refrigerant contained in a gas-liquid two-phase refrigerant from flowing out from an inner pipe so as to prevent generation of a liquid-back phenomenon.
(1) The present invention is a double-pipe heat exchanger including an outer pipe through which a high pressure liquid refrigerant flows, and an inner pipe having an inlet side end into which a low pressure gas-liquid two-phase refrigerant obtained by reducing pressure of the high pressure liquid refrigerant flows, and an outlet side end connected to a suction side part of a compressor, wherein the double-pipe heat exchanger includes a plurality of vertical pipes arranged in the up and down direction, and a curve pipe connecting ends of the plurality of vertical pipes, the outlet side end of the inner pipe is provided in an upper end of one vertical pipe, and the inlet side end of the inner pipe is provided in an upper end of the other vertical pipe.
With this configuration, while flowing through the inner pipe, the gas-liquid two-phase refrigerant flowing in from the inlet side end of the inner pipe performs heat exchange with the high pressure liquid refrigerant flowing through the outer pipe, and is evaporated to become a gas refrigerant, and then flows out from the outlet side end of the inner pipe. At this time, the outlet side end of the inner pipe is provided in the upper end of the one vertical pipe. Thus, even in a case where the gas-liquid two-phase refrigerant is not sufficiently evaporated and a liquid component (liquid refrigerant) remains, this liquid component does not easily go up in the inner pipe of the one vertical pipe, and hence does not easily flow out from the outlet side end. Therefore, a “liquid-back phenomenon” in which the liquid refrigerant comes into a compressor can be prevented.
Both the inlet side end and the outlet side end of the inner pipe are provided in the upper ends of the vertical pipes. Thus, without inverting the double-pipe heat exchanger, the refrigerant pipe can be connected, so that a pipe connecting task can be easily performed.
(2) Preferably, in the above configuration, the two vertical pipes are provided, and lower ends of the vertical pipes are connected by the curve pipe.
With such a configuration, the double-pipe heat exchanger can achieve a simple configuration, and by reducing a curve pipe part, a pressure loss of the refrigerant can be decreased.
(3) An air conditioner of the present invention includes a compressor, a condenser for condensing a high pressure gas refrigerant compressed by the compressor, a pressure reduction mechanism for reducing pressure of the condensed high pressure liquid refrigerant, an evaporator for evaporating the low pressure refrigerant after pressure reduction, and the double-pipe heat exchanger according to (1) or (2) described above, the double-pipe heat exchanger for supercooling the high pressure liquid refrigerant condensed by the condenser before reducing the pressure of the refrigerant by the pressure reduction mechanism.
(4) Preferably, in the above air conditioner, the curve pipe connected to lower ends of the plurality of vertical pipes in the double-pipe heat exchanger is supported on a bottom frame of a casing in the air conditioner via a support member.
With such a configuration, in a part of the curve pipe where strength is relatively high, the double-pipe heat exchanger can be stably supported.
According to the present invention, while the double-pipe heat exchanger can achieve a compact configuration, the liquid refrigerant contained in the gas-liquid two-phase refrigerant can be suppressed from flowing out from the inner pipe so as to prevent generation of the liquid-back phenomenon.
An air conditioner 1 is for example a multiple type air conditioner for a building in which a refrigerant circuit 10 is formed in such a manner that a plurality of indoor units 3 is connected in parallel to one or a plurality of outdoor unit 2 so as to circulate a refrigerant.
In the outdoor unit 2, compressors 11, a four way valve 12, an outdoor heat exchanger 13, an outdoor expansion valve 14, a supercooling heat exchanger 31, and the like are provided. These parts are connected by a refrigerant pipe so as to form the refrigerant circuit. A fan 23 is provided in the outdoor unit 2. In the indoor unit 3, an indoor expansion valve 15, an indoor heat exchanger 16, and the like are provided. The four way 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 stop valve 18 and a liquid side stop valve 19 are provided in terminal portions of the inside refrigerant circuit of the outdoor unit 2. The gas side stop valve 18 is arranged on the side of the four way valve 12, and the liquid side stop valve 19 is arranged on the side of the outdoor expansion valve 14. The gas side refrigerant communication pipe 17a is connected to the gas side stop valve 18, and the liquid side refrigerant communication pipe 17b is connected to the liquid side stop valve 19.
In a case where a cooling operation is performed in the air conditioner 1 with the above configuration, the four way valve 12 is retained in a state shown by solid lines in
On the other hand, in a case where a heating operation is performed, the four way valve 12 is retained in a state shown by broken lines in
The supercooling heat exchanger 31 of the present embodiment is used for supercooling the high pressure liquid refrigerant flowing out from the outdoor heat exchanger 13 before reducing the pressure by the indoor expansion valve 15 at the time of the cooling operation as described above. In the present embodiment, the supercooling heat exchanger 31 is provided in a part of the refrigerant pipe (called as a main refrigerant pipe 25) between the outdoor expansion valve 14 and the liquid side stop valve 19.
The refrigerant circuit has a bypass refrigerant circuit 26 in which a part of the refrigerant condensed in the outdoor heat exchanger 13 (high pressure liquid refrigerant) is diverted from the main refrigerant pipe 25, the cooling refrigerant serving as a cooling source is supplied to the supercooling heat exchanger 31, and then the cooling refrigerant is returned to a suction side part of the compressors 11. Specifically, the bypass refrigerant circuit 26 has a diverting pipe 27 by which the refrigerant is diverted from a part of the main refrigerant pipe 25 between the outdoor expansion valve 14 and the supercooling heat exchanger 31, the diverting pipe 27 being connected to an inlet of the cooling refrigerant in the supercooling heat exchanger 31, and a joining pipe 28 extending from an outlet of the cooling refrigerant in the supercooling heat exchanger 31 and joining a pipe of the suction side part of the compressors 11.
A bypass expansion valve 29 for reducing the pressure of the refrigerant is provided in the diverting pipe 27. The bypass expansion valve 29 is formed by an electric valve or the like for reducing the pressure of the high pressure liquid refrigerant flowing through the diverting pipe 27 so as to make the refrigerant 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. A liquid component (liquid refrigerant) contained in the gas-liquid two-phase refrigerant is evaporated by the heat exchange with the high pressure liquid refrigerant to become a gas refrigerant, and suctioned by the compressors 11.
The supercooling heat exchanger 31 is formed in a U curved structure. Specifically, the supercooling heat exchanger 31 includes two vertical pipes 34A and 34B, and a curve pipe 35 connecting ends of the two vertical pipes 34A and 34B. The curve pipe 35 connects lower ends of the two vertical pipes 34A and 34B. Therefore, inlet side ends 32A and 33A and outlet side ends 32B and 33B of the refrigerant are provided in upper ends of the two vertical pipes 34A and 34B.
The gas-liquid two-phase cooling refrigerant after the pressure reduction by the bypass expansion valve 29 flows into the inner pipe 33 of the supercooling heat exchanger 31 from the inlet side end 33A, performs the heat exchange with the high pressure liquid refrigerant flowing through the outer pipe 32 while flowing through the inner pipe 33 to become the gas refrigerant, and flows out from the outlet side end 33B. However, in a case where the liquid component of the gas-liquid two-phase refrigerant is not completely evaporated by the heat exchange with the high pressure liquid refrigerant, and when the liquid component flows out from the outlet side end 33B, the liquid component is suctioned by the compressors 11 and a liquid-back phenomenon is generated, so as to cause a decrease in a performance of the compressors 11.
In the present embodiment, the outlet side end 33B of the inner pipe 33 is provided in the upper end of the vertical pipe 34B. Thus, even when the liquid component of the gas-liquid two-phase refrigerant remains unevaporated, the liquid component does not easily go up toward the outlet side end 33B of the inner pipe 33, and does not easily flow out from the end 33B. Therefore, the liquid-back phenomenon to the compressors 11 can be suppressed. The liquid component of the gas-liquid two-phase refrigerant performs the heat exchange with the high pressure liquid refrigerant in the outer pipe 32 while remaining in the curve pipe 35 to become the gas refrigerant, and then flows out from the outlet side end 33B. Meanwhile, since the two vertical pipes 34A and 34B are connected by the curve pipe 35 having no horizontal part, drift (up-down separation of the liquid component and a gas component) of the gas-liquid two-phase refrigerant between the two vertical pipes 34A and 34B can be suppressed as far as possible.
Both the inlet side end 32A and the outlet side end 32B of the outer pipe 32, and the inlet side end 33A and the outlet side end 33B of the inner pipe 33 in the supercooling heat exchanger 31 are provided on the same side (upper side) in the up and down direction. Thus, the refrigerant pipe can be connected to these parts without inverting the supercooling heat exchanger 31 upside down. Therefore, a task of connecting the refrigerant pipe to the supercooling heat exchanger 31 can be performed with favorable workability.
The supercooling heat exchanger 31 is attached onto a bottom frame 43 in a casing of the outdoor unit 2 via a support member 40. This support member 40 is made of rubber, synthetic resin, or the like, and fixed to the bottom frame 43 by fixing tools 42 including bolts, nuts, and the like. A fitting recessed portion 41 recessed in a curved shape is formed on an upper surface of the support member 40. The supercooling heat exchanger 31 is supported by the support member 40 by fitting the curve pipe 35 into the fitting recessed portion 41 and fixing the support member 40 and the curve pipe 35 by a fastening band or the like. The supercooling heat exchanger 31 has relatively high strength in a part of the curve pipe 35. Thus, the supercooling heat exchanger 31 can be stably supported by the support member 40.
A supercooling heat exchanger 31 shown in
The present invention is not limited to the above embodiments but can be appropriately changed within the scope of the invention described in the claims.
For example, the supercooling heat exchanger (double-pipe heat exchanger) 31 of the present invention can also be applied to a refrigerant circuit shown in
In the supercooling heat exchanger 31 shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-262525 | Nov 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/078678 | 11/6/2012 | WO | 00 | 5/15/2014 |
