JP2008032298A - Internal heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal heat exchanger not performing heat exchange when temperatures of refrigerants are reversed between the high-pressure side and the low-pressure side of the internal heat exchanger. <P>SOLUTION: In this internal heat exchanger 7 disposed in a refrigerating cycle 1 cooling air by circulating the refrigerant, and exchanging heat between the refrigerant flowing in a high pressure-side passage 8 at the upstream with respect to an expansion valve 4 and the refrigerant flowing in a low pressure-side passage 9 at the downstream with respect to an evaporator 5, a heat transferring element 10 for transferring heat from the high pressure-side passage 8 to the low pressure-side passage 9 by utilizing latent heat is disposed between the high pressure-side passage 8 and the low pressure-side passage 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal heat exchanger provided in a refrigeration cycle that cools intake air by circulating a refrigerant.

  Conventionally, in a refrigeration cycle, the refrigerant pressurized by the compressor is cooled by exchanging heat with the outside air using a condenser, depressurized by passing through an expansion valve, evaporated by an evaporator, and returned to the compressor. Comparison between the relatively high-temperature refrigerant flowing in the high-pressure side passage and the low-pressure side passage by providing an internal heat exchanger that is joined to both the high-pressure side passage upstream and the low-pressure side passage downstream of the evaporator. A structure for exchanging heat with a refrigerant having a low temperature is known (for example, Patent Document 1).

In this prior art, the temperature of the refrigerant flowing into the evaporator through the expansion valve is lowered by cooling the refrigerant flowing in the high-pressure side passage upstream of the expansion valve by the internal heat exchanger. Ability can be improved.
JP 2000-320909 A

  However, in the above-described prior art, when the outside air temperature decreases, the temperature of the refrigerant cooled by heat exchange with the outside air in the condenser decreases, and the temperature of the refrigerant flowing into the high pressure side of the internal heat exchanger decreases. Therefore, a phenomenon may occur in which the temperature of the refrigerant on the high-pressure side of the internal heat exchanger is lower than the temperature of the refrigerant on the low-pressure side.

  Here, when the liquid refrigerant is supplied from the evaporator to the compressor, the compressor may be destroyed. Therefore, the refrigerant supplied from the evaporator to the compressor needs to be completely vaporized. Then, when a temperature reversal phenomenon occurs between the high-pressure side and the low-pressure side of the internal heat exchanger, the low-pressure side refrigerant is cooled by the high-pressure side refrigerant having a lower temperature. There was a possibility that the liquid refrigerant would be supplied.

  Therefore, an object of the present invention is to obtain an internal heat exchanger that does not exchange heat when the refrigerant temperature is reversed between the high pressure side and the low pressure side of the internal heat exchanger.

  In the present invention, heat exchange is performed between the refrigerant flowing in the high pressure side passage upstream of the expansion valve and the refrigerant flowing in the low pressure side passage downstream of the evaporator, which is provided in the refrigeration cycle that cools the air by circulating the refrigerant. In the internal heat exchanger for performing the above, a heat transfer element for transferring heat from the high pressure side passage to the low pressure side passage using latent heat is interposed between the high pressure side passage and the low pressure side passage. The most important feature.

  According to the present invention, heat is transferred from the high pressure side passage to the low pressure side passage by the heat transfer element interposed between the high pressure side passage upstream of the expansion valve and the low pressure side passage downstream of the evaporator. The temperature of the refrigerant flowing into the evaporator via the expansion valve is lowered, and the cooling capacity of the evaporator is improved. On the other hand, when the outside air temperature decreases and the temperature of the refrigerant flowing in the high-pressure side passage becomes lower than the temperature of the refrigerant flowing in the low-pressure side passage, the high-pressure side passage and the low-pressure side by the heat transfer element Since heat transfer with the passage is not performed, heat exchange can be prevented. As a result, the refrigerant flowing in the low pressure side passage downstream from the evaporator is not excessively cooled and the liquid refrigerant is not supplied to the compressor, so that the compressor can be prevented from being destroyed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a refrigeration cycle applied to a vehicle air conditioner or the like is illustrated.

  (First Embodiment) FIG. 1 is a perspective view showing an internal heat exchanger according to this embodiment, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 4 is a block diagram of a refrigeration cycle including the internal heat exchanger of the present embodiment.

  A refrigeration cycle, for example, a carbon dioxide air conditioner 1 shown in FIG. 4 includes a compressor 2 that pressurizes and discharges a refrigerant made of carbon dioxide, and a condenser (gas cooler) 3 that cools the refrigerant sent from the compressor 2 by heat exchange with outside air. The expansion valve 4 that depressurizes the refrigerant sent from the condenser 3, the evaporator 5 that cools the intake air by evaporating the refrigerant sent from the expansion valve 4, the refrigerant sent from the evaporator 5, and the refrigerant And an accumulator 6 for delivering a gaseous refrigerant to the compressor 2.

  As shown in FIGS. 1 to 4, the internal heat exchanger 7 of the present embodiment includes a high pressure side passage 8 provided on the upstream side of the expansion valve 4 and a low pressure side passage 9 provided on the downstream side of the accumulator 6. And a heat transfer element 10 interposed between the high-pressure side passage 8 and the low-pressure side passage 9 to transfer heat from the high-pressure side passage 8 to the low-pressure side passage 9 using latent heat. The heat transfer element 10 has a heat conductivity, and includes a sealed case 11 formed of a casing and having a sealed space formed therein, and a working fluid sealed in the sealed case 11, for example, water 12. In a substantially vacuum state where non-condensable gas such as air is discharged from the sealed space of the sealed case 11, a volume of water 12 smaller than the volume of the sealed space is enclosed.

  The high-pressure side passage 8 is arranged in parallel at a predetermined interval and is connected to the pair of header tanks 13, 14 extending in the horizontal direction and the pair of header tanks 13, 14 at both ends and joined to the lower surface of the sealed case 11. The one end of one header tank 13 is provided with a high pressure inlet 16 connected to the condenser 3, and the other end of the header tank 14 is connected to the expansion valve 4. A high pressure outlet 17 is provided.

  Similarly, the low-pressure side passage 9 is disposed above the header tanks 13 and 14, and a pair of header tanks 18 and 19 that are arranged in parallel at a predetermined interval and extend in the horizontal direction, and the pair of header tanks 18 and 18 19 is composed of a low-pressure heat transfer tube 20 that is communicated at both ends and joined to the upper surface of the sealed case 11. One end of one header tank 18 is provided with a low-pressure inlet 21 connected to the accumulator 6. A low pressure outlet 22 connected to the compressor 2 is provided at one end of the other header tank 19.

  In this embodiment, when the temperature of the refrigerant flowing in the high-pressure side passage 8 is higher than the temperature of the refrigerant flowing in the low-pressure side passage 9, the heat of the high-pressure side passage 8 is transferred to the water 12 through the sealed case 11. When transmitted, since water 12 is sealed in a vacuum state, it boils and water vapor reaches the upper inner wall surface.

  Next, since the low pressure heat transfer tube 20 is joined to the upper surface of the sealed case 11, heat is absorbed by the refrigerant in the low pressure heat transfer tube 20 via the low pressure heat transfer tube 20, and the water 12 in the sealed case 11 is condensed by heat dissipation. It becomes liquid and falls to the inner wall surface below.

  In this way, heat is transferred from the high-pressure side passage 8 to the low-pressure side passage 9 by the latent heat of the water 12 in the heat transfer element 10, so that the temperature of the refrigerant in the high-pressure side passage 8 is lowered, and the refrigerant in the low-pressure heat transfer tube 20. Temperature rises.

  On the other hand, when the outside air temperature decreases, the temperature of the refrigerant flowing in the high-pressure side passage 8 decreases, and becomes lower than the temperature of the refrigerant flowing in the low-pressure side passage 9, the water 12 Therefore, no heat is transferred from the high pressure side passage 8 to the low pressure side passage 9 by the heat transfer element 10. Even if the temperature of the refrigerant flowing in the low-pressure side passage 9 is relatively high, the low-pressure side passage 9 is separated from the water 12 accumulated in the lower part of the sealed case 11, and the water 12 is removed by the heat of the low-pressure side passage 9. Since heating is not performed, heat transfer from the low pressure side passage 9 to the high pressure side passage 8 is not performed.

  According to the present embodiment described above, when the temperature of the refrigerant flowing in the high-pressure side passage 8 is relatively high, heat transfer is performed from the high-pressure side passage 8 to the low-pressure side passage 9 by the heat transfer element 10. As a result, the temperature of the refrigerant flowing into the evaporator 5 is reduced, and the cooling capacity of the evaporator 5 is improved. Further, when the temperature of the refrigerant flowing in the high pressure side passage 8 becomes lower than the temperature of the refrigerant flowing in the low pressure side passage 9, the heat transfer between the high pressure side passage 8 and the low pressure side passage 9 is performed by the heat transfer element 10. Therefore, it is possible to prevent the refrigerant flowing in the low-pressure side passage 9 downstream from the evaporator 5 from being excessively cooled.

  In the present embodiment, the case where the sealed case 11 is formed of a casing is illustrated, but the present invention is not limited to this, and the sealed case is formed by a flat tube such as a drawing tube in which a sealed space is formed. It can also be configured. Further, in the present embodiment, the case where water 12 is sealed in the sealed case 11 is exemplified. However, as another working fluid, any one of alcohol and a new alternative substance HFC (Hydro / Fluoro / Carbon) belonging to alternative chlorofluorocarbons is used. It can also be used and the new alternative HFC includes R134R and R152R.

  (Second Embodiment) FIG. 5 is a perspective view showing an internal heat exchanger according to this embodiment, FIG. 6 is a cross-sectional view taken along the line CC of FIG. 5, and FIG. 7 is an internal heat exchange of FIG. It is sectional drawing which shows the state in which the container inclined. 5 to 7, the same reference numerals are assigned to the same components as those shown in FIGS.

  The internal heat exchanger 30 of the present embodiment shown in FIGS. 5 to 7 is different in the structure of the heat transfer element 31 from that shown in FIGS. It is the same. That is, in the heat transfer element 31, by providing a plurality of partition walls 33 extending in the vehicle width direction in the sealed case 32, the inside of the sealed case 32 is partitioned into a plurality of sealed chambers 34, and the sealed space of each sealed chamber 34. Water 35 having a volume smaller than the volume of the sealed space is sealed in a substantially vacuum state in which non-condensable gas such as air is discharged from.

  In the present embodiment, when the temperature of the refrigerant flowing through the high-pressure side passage 8 is higher than the temperature of the refrigerant flowing through the low-pressure side passage 9, the heat of the high-pressure side passage 8 passes through the sealed case 32 to each sealed chamber. When the water 35 is transferred to the water 35, the water 35 boils, the water vapor reaches the upper inner wall surface, dissipates heat when the water vapor changes its state to a liquid state, and the heat is a refrigerant in the low-pressure heat transfer tube 20. The heat is transferred from the high-pressure side passage 8 to the low-pressure side passage 9. At this time, the water 35 in each sealed chamber 34 is condensed by heat radiation and becomes liquid, and falls to the inner wall surface below.

  On the other hand, when the outside air temperature decreases, the temperature of the refrigerant flowing in the high-pressure side passage 8 decreases, and becomes lower than the temperature of the refrigerant flowing in the low-pressure side passage 9, the upper inner wall surface in each sealed chamber 34 Since the water 35 is not cooled and condensed, heat is not transferred from the high pressure side passage 8 to the low pressure side passage 9 by the heat transfer element 31. Even if the temperature of the refrigerant flowing in the low-pressure side passage 9 is relatively high, the low-pressure side passage 9 is separated from the water 35 accumulated below each sealed chamber 34, and the water 35 is removed by the heat of the low-pressure side passage 9. Since heating is not performed, heat transfer from the low pressure side passage 9 to the high pressure side passage 8 is not performed.

  Also in the present embodiment described above, when the temperature of the refrigerant flowing in the high-pressure side passage 8 is relatively high, heat transfer is performed from the high-pressure side passage 8 to the low-pressure side passage 9 by the heat transfer element 31, so As a result, the temperature of the refrigerant flowing into the evaporator 5 decreases and the cooling capacity of the evaporator 5 is improved. Further, when the temperature of the refrigerant flowing in the high pressure side passage 8 becomes lower than the temperature of the refrigerant flowing in the low pressure side passage 9, the heat transfer between the high pressure side passage 8 and the low pressure side passage 9 is performed by the heat transfer element 31. Therefore, it is possible to prevent the refrigerant flowing in the low-pressure side passage 9 downstream from the evaporator 5 from being excessively cooled. Further, in the present embodiment, when the vehicle is tilted in the front-rear direction, the lower inner wall surface in each sealed chamber 34 is covered with water 35 as shown in FIG. Since it does not contact the upper inner wall surface in the sealed chamber 34, the effect of transferring heat from the high-pressure side passage 8 to the low-pressure side passage 9 using the latent heat of the water 35 can be maintained.

  In this embodiment, the case where the plurality of partition walls 33 extending in the vehicle width direction are provided in the sealed case 32 to divide into the plurality of sealed chambers 34 is illustrated, but the plurality of partition walls extending in the vehicle front-rear direction are also illustrated. It can also be provided. In this case, even if the vehicle is inclined in the width direction, the lower inner wall surface in each sealed chamber is covered with water, and the water does not contact the upper inner wall surface in each sealed chamber. The effect of transferring heat from the side passage 8 to the low-pressure side passage 9 can be maintained. In the present embodiment, the case where water 35 is sealed in the sealed case 11 is exemplified. However, as the other working fluid, any one of alcohol and a new alternative substance HFC (Hydro / Fluoro / Carbon) belonging to alternative chlorofluorocarbons is used. It can also be used and the new alternative HFC includes R134R and R152R.

The perspective view which shows the internal heat exchanger which concerns on 1st Embodiment of this invention. Sectional drawing in alignment with the AA of FIG. Sectional drawing which follows the BB line of FIG. The block diagram of a refrigerating cycle provided with the internal heat exchanger which concerns on 1st Embodiment of this invention. The perspective view which shows the internal heat exchanger which concerns on 2nd Embodiment of this invention. Sectional drawing which follows the CC line | wire of FIG. Sectional drawing which shows the state in which the internal heat exchanger of FIG. 5 inclined.

Explanation of symbols

1 Carbon dioxide air conditioner (refrigeration cycle)
4 Expansion Valve 5 Evaporator 7 Internal Heat Exchanger 8 High Pressure Side Passage 9 Low Pressure Side Passage 10 Heat Transfer Element 11 Sealed Case 12 Water (Working Fluid)

Claims (3)

Refrigerating cycle (1) that cools the air by circulating the refrigerant, the refrigerant flowing in the high pressure side passage (8) upstream from the expansion valve (4) and the low pressure side passage (9) downstream from the evaporator (5) In the internal heat exchanger (7) that performs heat exchange with the refrigerant flowing through
A heat transfer element (10) for transferring heat from the high pressure side passage (8) to the low pressure side passage (9) using latent heat between the high pressure side passage (8) and the low pressure side passage (9). ), An internal heat exchanger.   The said heat transfer element (10) is provided with the airtight case (11) which has heat conductivity, and the working fluid (12) enclosed with this airtight case (11). Internal heat exchanger.   The internal heat exchanger according to claim 2, wherein the working fluid (12) is made of any one of water, alcohol, and a new alternative material HFC belonging to alternative chlorofluorocarbons.

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