JP2007278676A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of having difficulty in combining optimum performance of a condenser and an evaporator in a conventional heat exchanger. <P>SOLUTION: A gas side heat exchange part 102 has four paths with tubes of piping lines 105a, 105b, 105c, 105d arranged in parallel in a gas side heat exchange fin 104, and a liquid side heat exchange part 103 has tubes of piping lines 107a, 107b, 107c, 107d arranged in a liquid side heat exchange fin 106. Check valves 108a, 108b, 108c, 108d, 108e are arranged in front and in the rear of the liquid side heat exchange part 103, and it is constituted to change the number of paths by the direction of a refrigerant flowing in a heat exchanger 101. Performance improvement of a liquid phase part in condensation and suppression of pressure loss of a gas phase or gas-liquid two-phase part in evaporation are thereby combined to provide the heat exchanger of further efficient heat exchange performance in both cooling and heating operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat pump cycle mainly used for an air conditioner or the like, and it is changed to a path suitable for each case when functioning as an evaporator and when functioning as a condenser. The technology that can obtain the performance is provided.

  In an air conditioner that performs air conditioning using a refrigeration and a heat pump cycle, the heat exchanger functions as both an evaporator and a condenser. The refrigerant changes its state from a gas-liquid two-phase state to a gas phase in the evaporator and from the gas phase to the liquid phase in the condenser, and the direction of the refrigerant flowing through the heat exchanger is reversed between the evaporator and the condenser. The heat transfer performance in the pipe of the heat exchanger is greatly affected by the flow rate of the refrigerant, and the higher the flow rate, the better the performance. That is, in a condenser in which the refrigerant changes from the gas phase to the liquid phase and the flow velocity greatly decreases in the liquid phase portion, the efficiency of the system can be improved by increasing the flow velocity by reducing the number of passes. On the other hand, in an evaporator in which the refrigerant changes from a gas-liquid two-phase state to a gas phase and the flow velocity is higher than that of a condenser and pressure loss is likely to increase, the efficiency of the system decreases if the number of passes is reduced too much.

  In the prior art, as a method of solving this problem, a combination of check valves is used, and when the heat exchanger functions as a condenser, it is operated in one pass, and when it functions as a condenser, it is operated in two passes. In some cases, both cooling and heating are to be operated efficiently (see, for example, Patent Document 1). Another method is to use a refrigerant flow switching control means such as a three-way valve instead of a check valve, and not only switching the cooling / heating operation but also the size of the air-conditioning load and the outdoor heat exchanger. Some devices perform an efficient operation by controlling the number of passes of the device (for example, see Patent Document 2).

  FIG. 2 shows a configuration diagram of the cooling and heating cycle of the air-conditioning apparatus using the heat pump heat exchanger shown in Patent Document 1, and FIG. 3 shows a configuration diagram of the air conditioner shown in Patent Document 2. The cooling cycle 20 in FIG. 2 includes a compressor 21, a four-way valve 25, an outdoor heat exchanger 23, a decompressor 24, an indoor heat exchanger 22, and the like. The indoor heat exchanger 22 is provided with check valves 41, 42 and 43, and the outdoor heat exchanger 23 is provided with check valves 51, 52 and 53. During the cooling operation, the refrigerant flows in the direction of the solid arrow 71, the outdoor heat exchanger 23 is one path following the path from the block 61 to the block 62, and the indoor heat exchanger 22 has the blocks 31 and 32 in parallel. Drive in 2 passes. In the case of heating operation, the refrigerant flows in the direction of the broken line arrow 72, the indoor heat exchanger 22 is operated in one pass, and the outdoor heat exchanger 23 is operated in two passes.

The air conditioner in FIG. 3 includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a decompressor 4, an indoor heat exchanger 5, and the like. The outdoor heat exchanger 3 is a three-way valve 6a, 6b that can be switched with two paths of the refrigerant flow paths 3a, 3b, and the indoor heat exchanger 5 is a three-way switchable with two paths of the refrigerant flow paths 5a, 5b. Valves 7a and 7b are provided. The control unit 8 controls the three-way valves 6a, 6b, 7a, 7b according to the operation mode of the cooling / heating and the magnitude of the air conditioning load, and the outdoor heat exchanger 3 and the indoor heat exchanger 5 are operated in one or two passes. I do.
Japanese Utility Model Publication No. 5-90267 Japanese Patent Laid-Open No. 9-264614

However, when one path is taken up, the refrigerant changes into a gas phase, a gas-liquid two phase, and a liquid phase, and the flow velocity greatly changes with the change. The gas phase portion originally has a high flow rate and high heat transfer performance, whereas the liquid phase portion has a low flow rate and lower heat transfer performance than the gas phase portion and the gas-liquid two-phase portion.

  In the conventional apparatuses described in Patent Document 1 and Patent Document 2, since the number of passes of the entire heat exchanger is switched, the refrigerant circulation amount per pass is changed to a gas phase portion or a gas-liquid two-phase portion having a high degree of dryness. If it is designed to match the flow rate of the liquid phase, the heat transfer performance of the liquid phase part will not be sufficiently improved, and if it is matched to the flow rate of the liquid phase part, the gas phase part and the gas-liquid two-phase part will rise too much and the pressure loss will increase. There was a problem that the performance of the system could not be fully utilized.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a heat exchanger that can obtain more efficient heat exchange performance by switching paths.

  In order to solve the above-mentioned conventional problems, the heat exchanger of the present invention has a number-of-pass changing means for changing the number of passes on the side where the ratio of the liquid refrigerant is high between when functioning as an evaporator and when functioning as a condenser. Is provided. Thereby, the performance improvement of the liquid phase part with the low flow rate of a refrigerant | coolant and the low heat transfer performance in a pipe | tube and the pressure loss suppression of a gaseous phase or a gas-liquid two-phase part can be made compatible.

  The heat exchanger according to the present invention includes path number changing means for changing the number of paths on the side having a higher liquid refrigerant ratio when functioning as an evaporator and functioning as a condenser, and improves the performance of the liquid phase part. The pressure loss of the gas phase or the gas-liquid two-phase part can be suppressed at the same time, and a heat exchanger with more efficient heat exchange performance can be provided in any operation of cooling and heating.

  1st invention is equipped with the pass number change means which changes the pass number by the side where the ratio of a liquid refrigerant is high in the case where it functions as an evaporator and the case where it functions as a condenser, and improves the performance of a liquid phase part, and a gaseous phase Alternatively, both the pressure loss suppression of the gas-liquid two-phase part is achieved, and more efficient heat exchange performance can be obtained in any of the cooling and heating operations.

  In the second aspect of the invention, the sum of the flow passage cross-sectional areas on the side where the liquid refrigerant ratio is high when functioning as a condenser is less than half that when functioning as an evaporator, and the pipe diameter changes. Even heat exchangers can be designed easily.

  In the third invention, in particular, in the first invention, a check valve is used as the pass number changing means, and a small and inexpensive configuration can be realized.

  In a fourth aspect of the invention, particularly in the third aspect of the invention, when the number of passes on the side where the ratio of the liquid refrigerant at the time of the condenser is high is 1 / n of that at the time of the evaporator, the number of check valves arranged is n (N−1) × (number of passes during condensation) if n is an odd number, and (n × (number of passes during condensation) +1) to (n−1) × (number of passes during condensation) if n is an even number. The number of passes), and even if n changes, the heat exchanger of the present invention can be easily configured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a heat exchanger according to the first embodiment of the present invention. In FIG. 1, the gas side heat exchange part 102 in which the refrigerant is in a gas-liquid two-phase state with a high gas ratio or gas ratio and the liquid-side heat exchange part in a gas-liquid two-phase or liquid phase state with a high liquid ratio. The heat exchanger 101 is composed of 103, and the gas side heat exchange unit 102 and the liquid side heat exchange unit 103 are each composed of a tube through which a refrigerant flows and fins for improving heat exchange performance. In FIG. 1, it is divided into two elements for convenience, but in practice it is reasonable to divide and configure one heat exchanger.

  In the gas side heat exchange unit 102, tubes of piping paths 105a, 105b, 105c, and 105d are arranged in parallel on the gas side heat exchange fins 104, for a total of four paths. In the liquid side heat exchange unit 103, tubes of piping paths 107a, 107b, 107c, and 107d are arranged on the liquid side heat exchange fins 106. The specifications of the fins and tubes are the same as those of the gas side heat exchange unit 102. In addition, check valves 108 a, 108 b, 108 c, 108 d, and 108 e are arranged before and after the liquid side heat exchange unit 103, and are configured so that the number of passes changes depending on the direction of the refrigerant flowing through the heat exchanger 101.

  In FIG. 1, when the heat exchanger 101 functions as a condenser, the check valves 108a, 108b, 108c, and 108d are closed by flowing the refrigerant in the directions of arrows 111 and 112 (rightward in the drawing). Only the check valve 108e is opened, and in the gas side heat exchange section 102, the refrigerant flows through the piping paths 105a, 105b, 105c, and 105d in four paths along the arrows 111a, 111b, 111c, and 111d, and the liquid side heat exchange. In the part 103, the pipe paths 107a, 107b, 107c, and 107d flow through one path along the arrow 112a.

  At this time, it is efficient to operate the liquid side heat exchanging unit 103 with a size, a refrigerant amount, or a control so that the refrigerant is in a liquid state. In the case where the refrigerant is R410A, for example, the density in the liquid state at 40 ° C. to 50 ° C. is about 10 times higher than that in the gas state, and the liquid side heat exchange unit 103 is configured in four passes like the gas side heat exchange unit 102. Since the heat transfer of the refrigerant in the heat exchanging unit 103 is significantly reduced, the heat exchanging performance of the liquid side heat exchanging unit 103 can be improved by using one path along the arrow 112a as shown in FIG.

  On the other hand, when the heat exchanger 101 functions as an evaporator, the check valves 108a, 108b, 108c, and 108d are opened and only the check valve 108e is closed by flowing the refrigerant in the directions of arrows 113 and 114. In the liquid side heat exchange unit 103, the refrigerant flows through the piping paths 107a, 107b, 107c, and 107d in four paths along the arrows 113a, 113b, 113c, and 113d, and in the gas side heat exchange unit 102, the piping paths 105a, 105b, 105c and 105d become a four-pass flow along arrows 114a, 114b, 114c, and 114d.

  At this time, the liquid side heat exchanging portion 103 evaporates along the flow in a gas-liquid two-phase state. For example, in the case of R410A, at 0 ° C. to 20 ° C., the liquid gas density ratio is 20 times or more and the average flow velocity is 10 It rises by 20 to 20 times. In the same one pass as when the pass is a condenser, the pressure loss increases because the flow velocity is high, and the average temperature of the liquid side heat exchange unit 103 becomes equal when the state of the refrigerant at the outlet of the liquid side heat exchange unit 103 is the same. Increases and heat exchange performance decreases. In FIG. 1, the heat exchange performance of the liquid side heat exchanging unit 103 can be improved by suppressing the increase in pressure loss by using a four-pass flow along the arrows 114 a, 114 b, 114 c, and 114 d.

  In the gas side heat exchange unit 102, the refrigerant density in the case of the condenser (40 ° C. to 50 ° C.) is, for example, 5 times or less in R410A at most compared to the case of the evaporator (0 ° C. to 20 ° C.). Even if the number of passes adjusted by condensation is changed by evaporation, the effect as that of the liquid side heat exchange unit 103 cannot be obtained.

  Regarding the change in the number of passes of the liquid side heat exchanging unit 103, the experimental results show a remarkable effect when the number of passes at the time of condensation is ½ that at the time of evaporation. The gas-side heat exchange part and the liquid-side heat exchange part can also be configured in a well-balanced manner, and if it is less than 1/5, the balance is deteriorated in the composition ratio of the gas-side heat exchange part and the liquid-side heat exchange part. It was.

  In addition, in FIG. 1, since the gas side heat exchange part 102 and the liquid side heat exchange part 103 use the tube of the same specification, in the above, the description of "the number of passes during condensation is less than half of that during evaporation" is used. However, when tubes with different specifications are used, the cross-sectional area of the flow path during condensation is less than half that during evaporation.

  In actual applications, the ratio of the number of passes at the time of condensation and the number of passes at the time of evaporation in the liquid side heat exchange section is an integer ratio, so it is difficult to determine unambiguously depending on the specifications of the heat exchanger. It is necessary to decide in conjunction with the specifications. When n is an odd number when the number of passes during condensation is 1 / n during evaporation, if n is an odd number, (n-1) x (number of passes during condensation), and n is an even number. From (n × (number of passes during condensation) +1) to (n + 1) × (number of passes during condensation).

  As a rule of arrangement, it is divided into blocks corresponding to the number of passes at the time of condensation, and check valves are arranged in each block as follows. First, when used as an evaporator, two paths are connected on the refrigerant inlet side of the liquid side heat exchange section, and one check valve is arranged so that the refrigerant flows from the check valve to the connection position. In FIG. 1, a check valve 108c is arranged at the connecting portion between the piping paths 107a and 107b. As described above, when one check valve is arranged in two passes with respect to all the passes on the evaporator inlet side, if n is an even number, the check valves can be arranged in the same manner as in FIG. When n is an odd number, there is one more pass, and this is ensured to be the condenser outlet. All the inlet sides of the check valves arranged in this way on the evaporator inlet side are connected together and connected to the apparatus.

  At the time of the evaporator, the check valve is arranged at the outlet side of the liquid side heat exchange part. First, determine one path as the refrigerant inlet at the time of the condenser, and connect two paths so that each path is connected to this. In the connection position, one check valve is arranged so that the refrigerant flows into the check valve during the evaporator. In FIG. 1, the piping path 107a is secured as a refrigerant inlet at the time of the condenser, and a check valve 108a is disposed at the connecting portion between the piping paths 107b and 107c.

  In this way, when one check valve is arranged in two passes for all the remaining passes on the outlet side of the liquid side heat exchange section, when n is an even number, it is the same as the piping route 107d in FIG. Therefore, one check valve is arranged so that the refrigerant flows into the check valve during the evaporator like the check valve 108b, and the liquid side heat exchange section outlet like the check valve 108e is arranged. A route is provided with a check valve that branches immediately and returns to the evaporator inlet. If there are a plurality of blocks, that is, the number of paths at the time of condensation, these paths may be merged. Therefore, the number of paths may be selected from 1 to several paths at the time of condensation. When n is an odd number, the check valve can be arranged without leaving a path. However, be careful that the path previously secured as the refrigerant outlet at the time of the condenser becomes the condenser outlet. Connect the outlet in the same way as the check valve on the evaporator inlet side.

  If this rule is followed, even if n changes, the heat exchanger of this invention can be comprised easily. In FIG. 1, the path switching is configured using an inexpensive check valve, and is automatically performed according to the flow direction, so that it can be easily realized at a low cost.

  The heat exchanger according to the present invention includes path number changing means for changing the number of paths on the side having a higher liquid refrigerant ratio when functioning as an evaporator and functioning as a condenser, and improves the performance of the liquid phase part. It is a heat exchanger with ideal heat exchange performance in both the cooling and heating operations, which is compatible with pressure loss suppression in the gas phase or gas-liquid two-phase part. Although it is particularly effective as an exchanger, it can be applied as a heat exchanger of a system in which the object to be cooled or heated is air, water or other fluid and solid, and the refrigeration cycle and the heat pump cycle are configured reversibly. Moreover, it has an effect irrespective of the kind of refrigerant.

The block diagram of the heat exchanger in Embodiment 1 of this invention Configuration diagram of apparatus using conventional heat exchanger described in Patent Document 1 Configuration diagram of apparatus using conventional heat exchanger described in Patent Document 2

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Heat exchanger 102 Gas side heat exchange part 103 Liquid side heat exchange part 104 Gas side heat exchange fin 105a, 105b, 105c, 105d Piping path 106 Liquid side heat exchange fin 107a, 107b, 107c, 107d Piping path 108a, 108b, 108c, 108d, 108e Check valve

Claims (4)

Functions as an evaporator and a condenser of a system that reversibly configures a refrigeration cycle and a heat pump cycle by switching the circulation direction of the refrigerant in a reversible direction, and functions as the evaporator and the condenser as a function of the liquid refrigerant. A heat exchanger characterized by comprising path number changing means for changing the number of paths on the higher ratio side. The sum of the channel cross-sectional areas on the side with a higher ratio of the liquid refrigerant when functioning as the condenser is 20% or more and 50% or less when functioning as the evaporator. The described heat exchanger. The heat exchanger according to claim 1, wherein the number-of-passes changing means is configured using a check valve. When the number of passes on the side where the ratio of the liquid refrigerant at the time of the condenser is high is set to 1 / n of that at the time of the evaporator, the number of check valves arranged is (n-1) × (condensation if n is an odd number. The number of passes when the number of passes is n (n × (number of passes during condensation) +1) to (n−1) × (number of passes during condensation) if n is an even number. 3. The heat exchanger according to 3.