JP2010025438A - Countercurrent plate fin type heat exchanger and air cycle refrigeration system for container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a countercurrent plate fin type heat exchanger improving heat exchange efficiency while minimizing increase in pressure loss. <P>SOLUTION: In the countercurrent plate fin type heat exchanger, plates 22 and corrugated plate-shaped heat transfer fins 23 are alternately laminated at a plurality of stages, and fluid flow passages 1c, 1e where gas is made to flow are constituted between the plates 22, 22 at each layer. The fluid flow passage at each layer is alternately divided into a high-temperature fluid flow passage 1e where high-temperature fluid is made to flow and a low-temperature fluid flow passage 1c where low-temperature fluid is made to flow, and the flowing directions of the high-temperature fluid flow passage 1e and the low-temperature fluid flow passage 1c oppose to each other. The shapes of the heat transfer fins 23 are set to be different between the high-temperature fluid flow passage 1e and the low-temperature fluid flow passage 1c. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a countercurrent plate fin heat exchanger and an air cycle refrigeration system for containers using the same.

Since the air cycle refrigeration cooling system uses air as a refrigerant, energy efficiency is insufficient as compared with the case of using chlorofluorocarbon or ammonia gas, but it is preferable in terms of environmental protection. In addition, in facilities where refrigerant air can be directly blown into, such as a refrigerated warehouse, the total cost may be reduced by omitting the internal fan, etc., and an air cycle refrigeration cooling system has been proposed for such applications. (For example, Patent Document 1).
Further, it is known that the theoretical efficiency of air cooling is equal to or higher than that of Freon or ammonia gas in a deep coal region of -30 ° C to -60 ° C. However, it is stated that obtaining the above-described theoretical efficiency of air cooling can only be achieved with optimally designed peripheral devices. The peripheral device is a compressor, an expansion turbine, or the like.

As the compressor and the expansion turbine, a turbine unit in which a compressor impeller and an expansion turbine impeller are attached to a common main shaft is used. The air cycle refrigeration system includes a heat recovery heat exchanger that exchanges heat between the return air flowing into the compressor from the freezer and the air before the expansion turbine inlet, and heat exchange between the air that has become hot in the compressor and an external cooling medium. A heat dissipation heat exchanger for cooling. When an air cycle refrigeration system is used for containers, it is required to reduce the size as well as improve the temperature efficiency of the heat exchanger that greatly contributes to the refrigeration capacity.
Japanese Patent No. 2623202

  The air cycle refrigeration system includes a heat recovery heat exchanger and a heat dissipation heat exchanger. The heat recovery heat exchanger exchanges heat between the return air flowing into the compressor from the freezer and the air before the inlet of the expansion turbine, and is an air-to-air heat exchanger. A heat exchanger for heat dissipation cools air that has become hot at the compressor by heat exchange with an external cooling medium, and in the case of a large refrigerated warehouse, chiller cooling water is often used as the cooling medium, Since the container refrigerator has no chiller, air must be used.

  As a heat exchanger capable of performing air-to-air heat exchange with high efficiency and realizing low loss, there is a countercurrent plate fin heat exchanger having a structure shown in FIG. As shown in the figure, the counterflow type plate fin type heat exchanger forms a multistage fluid flow path 31 by laminating plates 32 and heat transfer fins 33 in a plurality of stages, and the multistage fluid flow path 31 has a high temperature. Heat exchange is performed by flowing fluid and low-temperature fluid alternately. As the material of the plate 32 and the heat transfer fins 33, an aluminum material is often used because it has a good thermal conductivity and is lightweight and can be easily brazed. In order to increase the amount of heat exchange in this counterflow plate fin heat exchanger, it is effective to increase the fin area and the number of stages of the plate 32 and the heat transfer fins 33. On the other hand, when the container is used for a container, the arrangement space of the refrigeration unit is limited. Therefore, when the above-described measures for increasing the heat exchange amount are taken, the cross-sectional area of the fluid channel 31 including the plate 32 and the heat transfer fins 33 is taken. Has a drawback that the pressure loss is reduced and the pressure loss is increased. In the air cycle refrigeration system, improvement in heat exchange efficiency of the heat recovery heat exchanger and reduction in pressure loss in the path from the compressor to the expander greatly contribute to the refrigeration capacity.

An object of the present invention is to provide a countercurrent plate fin heat exchanger capable of improving heat exchange efficiency while minimizing an increase in pressure loss.
Another object of the present invention is to provide a container air cycle refrigeration system capable of improving refrigeration capacity by improving heat exchange efficiency.

In the countercurrent plate fin heat exchanger of the present invention, a plate and corrugated heat transfer fins are alternately stacked in a plurality of stages to constitute a fluid flow path through which gas flows between the plates of each layer. The fluid flow paths of each layer are alternately divided into a high temperature fluid flow path through which a high temperature fluid flows and a low temperature fluid flow path through which a low temperature fluid flows, and the flow directions of the high temperature fluid flow path and the low temperature fluid flow path face each other. In the counterflow plate fin heat exchanger, the heat transfer fins have different shapes in the high-temperature fluid channel and the low-temperature fluid channel.
By making the shape of the heat transfer fins different, for example, the heat transfer area of the fluid flow channel on the higher pressure side of the gas flowing in the high temperature fluid flow channel and the low temperature fluid flow channel is reduced. If the area is larger than the heat transfer area, the heat exchange efficiency can be improved while minimizing the increase in pressure loss.

In this invention, the wave arrangement pitch of the heat transfer fins of the fluid flow path on the side of the fluid flow path where the pressure of the inflowing gas is high is made narrower than the wave arrangement pitch of the heat transfer fins of the flow path of the fluid flow path where the pressure of the inflowing gas is low. May be.
If the wave arrangement pitch of the heat transfer fins in the fluid flow path on the side of the high-flowing gas flow is narrowed, the heat transfer area of the fluid flow path is widened, so that heat exchange is performed while minimizing the increase in pressure loss. Efficiency can be improved.

In this invention, even if the cross-sectional area of the conduction heat fin of the fluid flow path on the side where the pressure of the inflowing gas is high is made smaller than the cross-sectional area of the heat transfer fin of the fluid flow path on the side where the pressure of the inflowing gas is low good.
Reducing the cross-sectional area of the heat transfer fin of the fluid flow path on the side where the pressure of the inflowing gas is high may increase the number of layers of the plate and heat transfer fin without changing the area of the duct 21 of the heat exchanger. Therefore, heat exchange efficiency can be improved while minimizing an increase in pressure loss.

In this invention, the ridge height of the heat transfer fin of the fluid flow path on the side where the pressure of the inflowing gas is high is made lower than the height of the ridge height of the heat transfer fin of the fluid flow path on the side where the pressure of the inflowing gas is low. Also good.
If the height of the heat transfer fin in the fluid flow path on the side where the pressure of the inflowing gas is high is reduced, the number of stacked layers of plates and heat transfer fins can be increased without changing the area of the duct 21 of the heat exchanger. Thus, the heat exchange efficiency can be improved while minimizing the increase in pressure loss.

In the present invention, the plate and the heat transfer fin may be made of an aluminum alloy.
When the plate and the heat transfer fin are made of an aluminum alloy, the heat conductivity is good, the weight is light, and the heat exchanger can be easily configured by brazing.

The container air cycle refrigeration system of the present invention uses the counter-current plate fin heat exchanger of any one of the above-described inventions.
Thus, when the countercurrent plate fin heat exchanger of any of the inventions described above is used as a heat exchanger for an air cycle refrigeration system for containers, the refrigeration capacity is improved by improving the heat exchange efficiency of the heat exchanger. Can be improved.

In the countercurrent plate fin heat exchanger of the present invention, a plate and corrugated heat transfer fins are alternately stacked in a plurality of stages to constitute a fluid flow path through which gas flows between the plates of each layer. The fluid flow paths of each layer are alternately divided into a high temperature fluid flow path through which a high temperature fluid flows and a low temperature fluid flow path through which a low temperature fluid flows, and the flow directions of the high temperature fluid flow path and the low temperature fluid flow path face each other. In the counterflow plate fin heat exchanger, the heat transfer fins have different shapes in the high-temperature fluid flow path and the low-temperature fluid flow path, so that heat exchange efficiency can be improved while minimizing an increase in pressure loss. Improvements can be made.
The container air cycle refrigeration system of the present invention uses the countercurrent plate fin of the above invention and the heat exchanger, so that the refrigeration capacity can be improved.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1: shows the whole system diagram of the air cycle refrigeration system for containers using the counterflow type plate fin type heat exchanger of this embodiment. This container air cycle refrigeration system is a device that directly cools the air in a cooled part of a container freezer as a refrigerant, and the entire system is stored in a part of the container. First, the overall configuration of the air cycle refrigeration system will be described, and then the configuration of the countercurrent plate fin heat exchanger will be described.

  As shown in FIG. 1, this air cycle refrigeration system has a refrigerant path 1 extending from an in-compartment air inlet 1 a to an in-compartment outlet 1 b, which is opened in each cooled portion 12. An air compressor 6 of the turbine unit 5 for air cycle refrigeration, a heat exchanger 2 for heat dissipation, a heat exchanger 3 for heat recovery, and an air expander 7 for the turbine unit 5 are sequentially provided in the refrigerant path 1. .

  The air compressor 6 of the turbine unit 5 compresses the return air from the cooled portion 12 and flowing in through the heat recovery heat exchanger 3. The heat-dissipating heat exchanger 2 includes a high-temperature fluid channel 1d into which air that has been compressed by the air compressor 6 to high pressure and high temperature flows, and a low-temperature fluid channel 8 into which cooling air that is an external refrigerant flows. Heat exchange is performed between them, and the air compressed by the air compressor 6 is primarily cooled. The heat recovery heat exchanger 3 includes a high-temperature fluid passage 1e through which high-pressure and high-temperature air flows between the heat-dissipation heat exchanger 2 and the air expander 7, a cooled portion 12, and an air compressor 6 Heat exchange is performed with the low-temperature fluid flow path 1c into which the cooling air flows between, and the compressed air before entering the air expander 7 is secondarily cooled. The air expander 7 of the turbine unit 5 further cools and supplies the compressed air secondarily cooled by the heat recovery heat exchanger 3 to the cooled portion 12 by crushing and expanding.

  This container air cycle refrigeration system is a system that keeps the cooled part 12 at about 0 ° C. to −60 ° C., from the cooled part 12 to the suction port 1a in the refrigerant path 1 at a pressure of 0.1 MPa and at 0 ° C. Air of about -60 ° C flows in. Note that the numerical values of temperature and pressure shown below are examples that serve as a rough standard. The air that has flowed into the internal suction port 1a is used for air cooling in the subsequent stage in the refrigerant path 1 by heat exchange in the heat recovery heat exchanger 3, and the temperature is raised to 30 ° C. The heated air flows into the air compressor 6 of the turbine unit 5 with the pressure of 0.1 Mpa, where it is compressed to a pressure of 0.18 Mpa, and the temperature is raised to 110 ° C. by the compression. The compressed air is primarily cooled to 40 ° C. by the heat dissipation heat exchanger 2.

The 40 ° C. compressed air that has been primarily cooled by the heat dissipating heat exchanger 2 is further cooled to −20 ° C. by the heat recovery heat exchanger 3. The pressure is maintained at 0.18 Mpa when discharged from the air compressor 6.
The air cooled to −20 ° C. in the heat recovery heat exchanger 3 is adiabatically expanded by the air expander 7 of the turbine unit 5, cooled to −50 ° C., and discharged to the cooled portion 12 from the in-compartment outlet 1 b. Is done. This air cycle refrigeration system performs such a refrigeration cycle.

  In the turbine unit 5, a compressor impeller of the air compressor 6 and a turbine impeller of the air expander 7 are respectively attached to both ends of the main shaft 13 that is rotatably supported by bearings. A power unit 14 is coaxially provided on the main shaft 11, and the compressor impeller of the air compressor 6 is driven by the driving force generated by the power unit 14 and the power generated by the turbine impeller of the air expander 7.

  2A and 2B show a cross-sectional view and a side view of the heat recovery heat exchanger 3. This heat recovery heat exchanger 3 is composed of a counter-flow plate fin heat exchanger. That is, the heat recovery heat exchanger 3 includes, for example, a plurality of stages of plates 22 and corrugated heat transfer fins 23 stacked in a duct 21 having a square cross section, and a fluid flow between the plates 22. Paths 1c and 1e are configured. The fluid flow path of each layer has passed from the air compressor 6 through the heat-dissipating heat exchanger 2 and the high-temperature fluid flow path 1e into which high-pressure and high-temperature air flows, and the cooled portion 10 through the internal suction port 1a. The low-temperature fluid flow path 1c into which low-temperature air (atmospheric pressure) flows is alternately divided, and the flow directions of the high-temperature fluid flow path 1e and the low-temperature fluid flow path 1c are made to face each other. The high-temperature fluid channel 1e and the low-temperature fluid channel 1c are different from each other in the shape of the heat transfer fins 23.

  The plates 22 and heat transfer fins 23 constituting the heat recovery heat exchanger 3 are made of an aluminum alloy. When the plate 22 and the heat transfer fins 23 are made of an aluminum alloy, the heat recovery heat exchanger 3 can be easily configured by brazing with good heat conductivity and light weight.

In the heat exchanger having such a configuration, the pressure loss ΔP in the high-temperature fluid flow path 1e into which the high-pressure air compressed by the air compressor 6 flows can be calculated by the following equation (1).
ΔP = λ · L / d · ρu 2/2 ...... (1)
However,
λ: Resistance coefficient L: Channel length d: Channel equivalent diameter ρ: Fluid density u: Fluid flow velocity

In the case of the heat recovery heat exchanger 3, the water equivalent of the gas (air) flowing into the high temperature fluid channel 1e and the gas (air) flowing into the low temperature fluid channel 1c are equal, that is, the mass flow rate is constant. In this case, when the pressure of the inflowing gas (air) is doubled, the density ρ is doubled, but the volume of the gas (air) is halved and the flow velocity u is also halved. From this, it can be seen from the equation (1) that the pressure loss becomes 1/2 when the pressure of the inflowing gas (air) is doubled under the condition where the mass flow rate is constant.
Therefore, in the heat exchanger 3 for heat recovery, as described above, the shape of the heat transfer fins 23 is made different between the high-temperature fluid channel 1e and the low-temperature fluid channel 1c, so that high-temperature and high-pressure air is generated. The heat transfer area in the inflowing high-temperature fluid channel 1e is made wider than the heat transfer area in the low-temperature fluid channel 1c where the pressure of the inflowing air is low (atmospheric pressure), thereby minimizing the increase in pressure loss. The heat exchange efficiency is improved. That is, widening the heat transfer area of the fluid flow path increases pressure loss, but from the relationship of the above formula (1), even if the heat transfer area is widened in the high temperature fluid flow path 1e, The accompanying increase in pressure loss can be kept small.

  In this embodiment, in order to widen the heat transfer area of the high-temperature fluid flow path 1e, as shown in FIG. 2 (C) showing a part A of FIG. The wave arrangement pitch of the heat fins 23 is made narrower than the wave arrangement pitch of the heat transfer fins 23 of the low-temperature fluid flow path 1c. Specifically, each heat transfer fin 23 has a cross-sectional shape or a rectangular shape, and a wave-like flat peak portion 23a and a wave bottom surface portion 23b of each wave portion are in contact with the plate 22 on both sides, respectively. The portion is a partition plate portion 23c that divides each flow channel 1c, 1e into a plurality of parallel flow channel portions. Regarding the arrangement pitch of the partition plate portions 23c, the arrangement pitch of the high-temperature fluid flow paths 1e is made narrower than the arrangement pitch of the low-temperature fluid flow paths 1c.

  According to the heat recovery heat exchanger 3 composed of the countercurrent plate fin heat exchanger having this configuration, the heat transfer area of the high-temperature fluid flow path 1e on the side where the pressure of the inflowing air is high, Since it is made wider than the heat transfer area of the low-temperature low-temperature fluid flow path 1c, it is possible to improve the heat exchange efficiency while minimizing an increase in pressure loss.

  Moreover, in the container air cycle refrigeration system of FIG. 1 using the heat recovery heat exchanger 3 that improves the heat exchange efficiency, the refrigeration capacity can be improved. In particular, in this heat recovery heat exchanger 3, since the heat transfer efficiency is improved by widening the heat transfer area of the high-temperature fluid channel 1e, the volume of the heat exchanger is increased to improve the heat exchange efficiency. It does not increase in size and is easy to install in a container.

By making the wave arrangement pitch of the heat transfer fins 23 of the high-temperature fluid flow path 1e narrower than the wave arrangement pitch of the heat transfer fins 23 of the low-temperature fluid flow path 1c, the heat transfer area of the high-temperature fluid flow path 1e is widened. In the case of the embodiment, the pressure loss is increased by 10 to 40% compared to the case where the wave arrangement pitch of the heat transfer fins 23 is the same as that of the low temperature fluid flow path 1c, but the heat exchange efficiency is improved by 2 to 5%. In this case, the heat transfer area of the high-temperature fluid path 1e can be widened at low cost.
Moreover, in the container air cycle refrigeration system using the heat recovery heat exchanger 3 of this embodiment, the refrigeration capacity can be improved by about 300 to 400 W.

  In addition, although description was abbreviate | omitted in this embodiment, also about the heat exchanger 2 for heat dissipation, a counterflow type plate fin type heat exchanger made into the same structure as the heat exchanger 3 for heat recovery is used, and pressure loss is reduced. Reduction and improvement in heat exchange efficiency may be achieved.

  Further, in order to increase the number of layers of the plate and the heat transfer fins without changing the area of the duct 21 of the heat exchanger, the cross-sectional area of the heat transfer fins 23 of the high-temperature fluid channel 1e is changed to the low-temperature fluid channel 1c. The cross-sectional area of the heat transfer fins 23 may be smaller. Also in this case, the heat exchange efficiency can be improved while minimizing the increase in pressure loss.

  FIG. 3 shows another embodiment of the present invention. This embodiment is a heat recovery heat exchanger 3 composed of a countercurrent plate fin heat exchanger used in the container air cycle refrigeration system of FIG. 1 without changing the area of the duct 21 of the heat exchanger. In order to increase the number of stacked layers of the plate and the heat transfer fins, as shown in FIG. 3C, the height of the heat transfer fins 23 of the high temperature fluid channel 1e is set to the height of the heat transfer fins 23 of the low temperature fluid channel 1c. It is lower than the height of Namiyama. Other configurations are the same as those in the embodiment of FIG.

  In the case of this embodiment, the number of stacked stages of the plate and the heat transfer fin can be increased, so that the heat exchange efficiency can be improved while minimizing the increase in pressure loss.

In this implementation, the height of the heat transfer fins 23 in the high-temperature fluid flow path 1e is made lower than the height of the heat transfer fins 23 in the low-temperature fluid flow path 1c, thereby increasing the number of stacked layers of the plate and the heat transfer fins. In the case of the embodiment, the pressure loss is increased by 10 to 40% compared to the case where the wave height of the heat transfer fins 23 is the same as that of the low temperature fluid flow path 1c, but the heat exchange efficiency is improved by 2 to 5%.
Moreover, in the container air cycle refrigeration system using the heat recovery heat exchanger 3 of this embodiment, the refrigeration capacity can be improved by about 300 to 400 W.

  FIG. 4 shows another system diagram of the container air cycle refrigeration system in which the heat recovery heat exchanger 3 of each embodiment described above is used. This container air cycle refrigeration system is the same as the air cycle refrigeration system of FIG. 1 except that the second air compressor 9 for precompression and the second air compressor 9 in the stage preceding the air compressor 5 of the turbine unit 5 in the refrigerant path 1 The heat exchanger 10 for heat dissipation is provided in this order. The 2nd air compressor 9 consists of blowers etc., and is driven by the motive power part 9a. The second heat exchanger 10 is an external refrigerant and a high-temperature fluid flow path 1f into which air that has been compressed by the second air compressor 9 to a high pressure / high temperature (0.14 Mpa, 70 ° C.) flows. Heat exchange is performed with the low-temperature fluid flow path 11 into which the cooling air flows, and the air compressed by the second air compressor 9 is cooled (0.14 Mpa, 40 ° C.). Other configurations are the same as those of the air cycle refrigeration system of FIG.

  In each of the above embodiments, the case where the countercurrent plate fin heat exchanger having the above-described configuration is applied to the heat recovery heat exchanger 3 of the container air cycle refrigeration system has been described. Even if the plate fin heat exchanger is used as a heat exchanger of another refrigeration system, it can contribute to the improvement of the refrigeration capacity.

1 is a system diagram of a container air cycle refrigeration system in which a counterflow plate fin heat exchanger according to an embodiment of the present invention is used. (A) is sectional drawing of the heat exchanger for heat recovery of the air cycle refrigeration system, (B) is the side view, (C) is an expanded sectional view of the A section in (A). (A) is sectional drawing of the other structural example of the heat exchanger for heat recovery, (B) is the same side view, (C) is an expanded sectional view of the B section in (A). It is a systematic diagram of the other example of the air cycle refrigeration system for containers. (A) is sectional drawing of a prior art example, (B) is the side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1c ... Low temperature fluid flow path 1e ... High temperature fluid flow path 2 ... Heat exchanger 3 for heat dissipation ... Heat exchanger 6 for heat recovery ... Air compressor 7 ... Air expander 12 ... Cooled part 22 ... Plate 23 ... Heat transfer fin

Claims (7)

Plates and corrugated heat transfer fins are alternately stacked in a plurality of stages to form a fluid flow path through which a gas flows between the plates of each layer. In the counterflow type plate fin heat exchanger that is alternately divided into a fluid flow path and a low-temperature fluid flow path through which a low-temperature fluid flows, and in which the flow directions of the high-temperature fluid flow path and the low-temperature fluid flow path face each other,
A counter-flow plate fin heat exchanger in which the shape of the heat transfer fin is different between the high-temperature fluid channel and the low-temperature fluid channel.   2. The direction according to claim 1, wherein the heat transfer area of the high-temperature fluid flow path and the low-temperature fluid flow path on the side where the pressure of the inflowing gas is high is wider than the heat transfer area of the low-side fluid flow path. Flow type plate fin type heat exchanger.   3. The wave arrangement pitch of the heat transfer fins of the fluid flow path on the side where the pressure of the inflowing gas is low, and the wave arrangement pitch of the heat transfer fins on the side of the fluid flow path, where the pressure of the inflowing gas is low. Counterflow plate fin heat exchanger narrower than the pitch.   4. The heat transfer in the fluid flow path on the side where the pressure of the inflowing gas is lower than the cross-sectional area of the heat transfer fin of the fluid flow path on the side where the pressure of the inflowing gas is higher. Counter-flow plate fin heat exchanger that is smaller than the fin cross-sectional area.   5. The wave height of the heat transfer fin of the fluid flow path on the side where the pressure of the inflowing gas is high is set to the height of the flow path of the fluid flow path on the side where the pressure of the inflowing gas is low. Counterflow type plate fin type heat exchanger lower than the wave fin height of the heat fin.   6. The countercurrent plate fin heat exchanger according to claim 1, wherein the plate and the heat transfer fin are made of an aluminum alloy. An air cycle refrigeration system for containers using the countercurrent plate fin heat exchanger according to any one of claims 1 to 6.

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