JP2008082658A - Internal heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal heat exchanger considerably reducing manufacturing cost while maintaining heat exchanging performance. <P>SOLUTION: The internal heat exchanger comprises a high pressure side pipe 21 through which a high-pressure medium-temperature refrigerant flows, and a low pressure side pipe 22 through which a low-pressure low-temperature refrigerant lower in pressure and temperature than the high pressure side pipe flows, and exchanges heat between these refrigerants. The high pressure side pipe 21 is formed as a circular pipe smaller in both inner and outer diameters than the low pressure side pipe 22, and the high pressure side pipe 21 and the low pressure side pipe 22 are formed in spirally twisted structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal heat exchanger, and in particular, to a technique that enables maintenance of heat exchange performance and low-cost production.

  For example, refrigeration cycles using carbon dioxide as a refrigerant have been developed for automotive air conditioners. Among the devices constituting the refrigeration cycle, the internal heat exchanger includes a high-pressure side passage through which a high-pressure and intermediate-temperature refrigerant flows, and a low-pressure side passage through which a low-pressure and low-temperature refrigerant having a lower pressure and temperature flows. Heat is exchanged between the refrigerants flowing through both flow paths.

  As one of such internal heat exchangers, for example, a structure in which a high-pressure and high-temperature refrigerant flow is wrapped around a pipe line through which low-pressure and low-temperature refrigerant flows to perform heat exchange. Have been proposed (see, for example, Patent Document 1).

  In addition, an internal heat exchanger having a structure in which a high-pressure refrigerant pipe and a low-pressure refrigerant pipe are brazed, and both the brazed pipes are covered with a heat insulating material so as to be accommodated therein is proposed (for example, Patent Document 2). reference).

  In addition, an internal heat exchanger has been proposed in which a first refrigerant passage having a circular cross section is formed at the center of a cylindrical tube, and a plurality of second refrigerant passages are formed outside the first refrigerant passage so as to surround the first refrigerant passage. (For example, refer to Patent Document 3).

In addition, an internal heat exchanger having a structure in which a refrigerant inflow pipe and a refrigerant outflow pipe provided in a hermetic casing are twisted is proposed (see, for example, Patent Document 4).
Japanese Patent Laid-Open No. 2001-56188 (particularly described in FIG. 16) JP 2004-85183 A JP 2003-106784 A Japanese Utility Model Publication No. 58-49161

  However, in the technique described in Patent Document 1, the length for heat transfer on the low pressure side is insufficient and the heat exchange performance deteriorates, and the high pressure side pipe line becomes too long and the passage resistance becomes high. .

  With the technique described in Patent Document 2, the heat transfer efficiency per unit length is poor, and problems still remain in terms of heat exchange performance.

  In the technique described in Patent Document 3, since two refrigerant passages are formed in the same cylindrical tube, the coupling structure between each refrigerant passage and the connector becomes complicated, and the processing cost increases.

  In the technique described in Patent Document 4, two pipes are twisted together to increase heat exchange efficiency. However, since they have the same pipe diameter, a pipe through which a high-pressure and high-temperature refrigerant flows and a low-pressure and low-temperature refrigerant are In particular, the pressure resistance of the high-pressure side pipe and the heat exchange amount of the low-pressure side pipe are not sufficiently satisfactory with the flowing pipe.

  Therefore, the present invention has been made to solve the above-described problems, and an object thereof is to provide an internal heat exchanger that can greatly reduce the manufacturing cost while maintaining the heat exchange performance. .

  The invention according to claim 1 includes a high-pressure side pipe through which a high-pressure and intermediate-temperature refrigerant flows, and a low-pressure side pipe through which a low-pressure and low-temperature refrigerant having a lower pressure and temperature flow, and performs heat exchange between these refrigerants. A heat exchanger, wherein the high-pressure side pipe is a circular pipe having a smaller inner diameter and outer diameter than the low-pressure side pipe, and the high-pressure side pipe and the low-pressure side pipe are spirally connected to each other. It is characterized by.

  A second aspect of the present invention is the internal heat exchanger according to the first aspect, wherein a clad material is provided on an outer periphery of the high-pressure side pipe.

  Invention of Claim 3 is an internal heat exchanger of Claim 1 or Claim 2, Comprising: The internal diameter of the said low voltage | pressure side pipe is made into the range of 8-12 mm in an equivalent diameter, The internal diameter of the said high voltage | pressure side pipe In the range of 4 to 6 mm in terms of equivalent diameter.

  The invention according to claim 4 is the internal heat exchanger according to any one of claims 1 to 3, wherein the number of the high-pressure side pipes is at least two.

  A fifth aspect of the present invention is the internal heat exchanger according to any one of the first to fourth aspects, wherein the refrigerant is carbon dioxide gas.

  According to the first aspect of the present invention, since the high-pressure side pipe and the low-pressure side pipe are arranged close to each other in a spiral shape, the heat exchange length can be earned, and the heat per length of the internal heat exchanger can be obtained. Exchange efficiency is improved. In addition, since the end of the internal heat exchanger of the present invention is circular, the structure of the joint is simplified, and the cost can be greatly reduced. Further, according to the present invention, since the high-pressure side pipe has a smaller inner diameter and outer diameter than the low-pressure side pipe, the high-pressure side pipe improves the heat exchange amount and also the pressure resistance.

  According to the second aspect of the present invention, since the cladding material is provided on the outer periphery of the high-pressure side pipe, the high-pressure side pipe having a smaller outer diameter than the low-pressure side pipe has the cladding material, so that the expensive cladding material The amount can be reduced and the cost can be reduced.

  According to the third aspect of the invention, the cooling performance can be effectively improved by combining the optimum inner diameters of the high pressure side pipe and the low pressure side pipe.

  According to the fourth aspect of the present invention, since the two or more high-pressure side pipes cover the low-pressure side pipe, a heat insulating material becomes unnecessary, and the cost can be reduced.

  According to the fifth aspect of the present invention, since the pressure-resistant structure can be constructed at low cost, it is optimal for an air conditioner using carbon dioxide gas, which is essential to have an internal heat exchanger, as a refrigerant.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 is a system diagram of a vehicle air conditioner to which the internal heat exchanger of the present embodiment is applied, FIG. 2 shows the internal heat exchanger of the present embodiment, (A) is a side view, and (B). Is an end view, FIG. 3 is a PH diagram showing the relationship between pressure and enthalpy in the internal heat exchanger of the present embodiment, and FIG. 4 is a passage resistance of the high-pressure side pipe in the internal heat exchanger of the present embodiment. FIG. 5 is a characteristic diagram showing the passage resistance of the low-pressure side pipe in the internal heat exchanger of the present embodiment, and FIG. 6 is a characteristic showing the amount of heat exchange in the internal heat exchanger of the present embodiment. FIG. 7 is a side view showing another example of the internal heat exchanger of the present embodiment.

  The vehicle air conditioner uses carbon dioxide gas as a refrigerant, the compressor 1 that compresses the refrigerant, and an external heat exchanger that exchanges heat between the refrigerant compressed and heated by the compressor 1 and the outside air. 2, a first evaporator (evaporator) 3 disposed on the front seat side of the vehicle, a second evaporator 4 disposed on the rear seat side of the vehicle, and the first evaporator 3. A first internal heat exchanger 5 dedicated to the first evaporator and a second internal heat exchanger 6 dedicated to the second evaporator provided corresponding to the second evaporator 4. I have.

  A compressor 1 and an external heat exchanger 2 are provided in the engine room 7. A first evaporator 3 and a second evaporator 4 are provided in a portion 8 on the rear side from the engine room of the vehicle. The second internal heat exchanger 6 is provided from the engine room to the rear.

  A first expansion valve 9 is provided between the first evaporator 3 and the first internal heat exchanger 5. A second expansion valve 10 is provided between the second evaporator 4 and the second internal heat exchanger 6. An electromagnetic valve 11 is provided at the outlet of the external heat exchanger 2 to supply the refrigerant cooled by the external heat exchanger 2 to the first internal heat exchanger 5 or the second internal heat exchanger 6. Yes.

  The compressor 1 obtains a driving force from a motor (not shown) or a vehicle drive device, compresses the carbon dioxide gas in a gas phase, and discharges it as a high-temperature and high-pressure refrigerant.

  The external heat exchanger 2 heat-exchanges the refrigerant compressed and heated by the compressor 1 with the outside air to cool the refrigerant.

  The first evaporator 3 is disposed in an air conditioning duct provided on the front seat side, and evaporates the low-temperature and low-pressure refrigerant decompressed (expanded) by the first expansion valve 9.

  The first expansion valve 9 depressurizes (expands) the high-pressure refrigerant output from the first internal heat exchanger 5 to form a mist, and outputs the mist refrigerant to the first evaporator 3. To do.

  The second evaporator 4 is disposed in an air conditioning duct provided on the rear seat side, and evaporates the low-temperature and low-pressure refrigerant decompressed by the second expansion valve 10.

  The second expansion valve 10 decompresses the high-pressure refrigerant output from the second internal heat exchanger 6 to form a mist, and outputs the mist refrigerant to the second evaporator 4.

  The electromagnetic valve 11 functions to switch the flow path of the refrigerant that supplies the refrigerant cooled by the external heat exchanger 2 to the first evaporator 3 and the second evaporator 4. When operating only on the front seat side, the solenoid valve 11 is closed so that the refrigerant flows to the first evaporator 3.

  In the present embodiment, the first internal heat exchanger 5 and the second internal heat exchanger 6 are, as shown in FIG. 2, a high-pressure side pipe 21 through which a high-pressure / medium-temperature refrigerant flows, It consists of a low-pressure side pipe 22 through which low-temperature and low-temperature refrigerant flows at a low temperature, and heat exchange is performed between the refrigerants flowing through these pipes. Although only the first internal heat exchanger 5 is shown in FIG. 2, the second internal heat exchanger has the same structure.

  Each of the high-pressure side pipe 21 and the low-pressure side pipe 22 is formed as a circular pipe that forms a refrigerant flow path through which refrigerant flows, and a clad material (not shown) for solder connection is provided on the outer periphery thereof. It has been. The high-pressure side pipe 21 has both an inner diameter and an outer diameter smaller than those of the low-pressure side pipe 22. Furthermore, the high-pressure side pipe 21 and the low-pressure side pipe 22 have a structure in which they are spirally opposed along the longitudinal direction thereof. In other words, the high-pressure side pipe 21 and the low-pressure side pipe 22 having different inner diameters and outer diameters are formed by spirally contacting each other in the longitudinal direction so as to knit a so-called shim rope.

  The internal heat exchangers 5 and 6 have a structure in which two pipes are close to each other in a spiral shape, and both end portions thereof are independent end portions having gaps that can be connected to respective connectors. Both end portions 21A, 21B and 22A, 22B of the high-pressure side pipe 21 and the low-pressure side pipe 22 have a circular cross section, and can be connected with a conventional connector.

  The 1st and 2nd internal heat exchangers 5 and 6 are optimized so that it may become required maximum performance based on the PH diagram which shows the pressure and enthalpy (calorie | heat amount) shown in FIG. In particular, in order to improve the cooling performance, it is important to optimize the inner diameters of the high-pressure side pipe 21 and the low-pressure side pipe 22.

  4, 5, and 6 show the refrigerant flow rate of 1.100 kg / h, 2.150 kg / h, 3.200 kg / h when the flow path length is 1.400 mm, 2.800 mm, 3.1200 mm. The value of is shown.

  As shown in FIG. 4, when the inner diameter φHi of the high-pressure side pipe 21 is smaller than 4 mm, the passage resistance (ΔPgHi) is extremely increased. Therefore, the lower limit is preferably 4 mm or more. Therefore, the upper limit is preferably 6 mm at the maximum from the viewpoint of pressure resistance. That is, it is desirable that the inner diameter φHi of the high-pressure side pipe 21 is in the range of 4 to 6 mm in terms of equivalent diameter. The equivalent diameter D is a value represented by D = (4 × A) / L, where A is the cross-sectional area of the flow path of the pipe, and L is the peripheral length of the flow path (the length that the refrigerant gets wet). To do.

  As shown in FIG. 5, when the inner diameter φLow of the low-pressure side pipe 22 is smaller than 8 mm, the passage resistance (ΔPgLow) is extremely increased. Therefore, the lower limit is preferably 8 mm or more. Since the amount is small, the upper limit is preferably set to a maximum of 12 mm from the viewpoint of pressure resistance. That is, the inner diameter φLow of the low-pressure side pipe 22 is desirably 8 to 12 mm in terms of equivalent diameter.

  When the inner diameter φLow of the low-pressure side pipe 22 is 8 mm and the inner diameter φHi of the high-pressure side pipe 21 is 4 mm, the passage resistance is when the inner diameter φLow of the low-pressure side pipe 22 is 6 mm and the inner diameter φHi of the high-pressure side pipe 21 is 3 mm. There is an effect that the passage resistance can be reduced by 200 kPa. This is equivalent to a 10% improvement in cooling performance when the evaporation pressure of the evaporator is reduced by 200 kPa. As shown in FIG. 6, there is no problem because the heat exchange amount of the internal heat exchanger is 1200 W to 2400 W on the high pressure side and the low pressure side by setting the inner diameter within the above-described range.

  In FIG. 7, two high-pressure pipes 21 having a diameter and an inner diameter that are smaller than those of the low-pressure pipe 22 are used, and the two high-pressure pipes 21 and one low-pressure pipe 22 are close to each other in a spiral shape. Similar effects can be obtained even with the same structure. In particular, when two high-pressure side pipes 21 are used, the high-pressure side pipe 21 covers the low-pressure side pipe 22, thereby eliminating the need for a heat insulating material and reducing the cost. The number of the high-pressure side pipes 21 may be three or more as long as the heat exchange performance can be maintained.

It is a systematic diagram of the vehicle air conditioner to which the internal heat exchanger of this Embodiment is applied. The internal heat exchanger of this Embodiment is shown, (A) is a side view, (B) is an end view. It is a PH diagram which shows the relationship between the pressure and enthalpy in the internal heat exchanger of this Embodiment. It is a characteristic view which shows the passage resistance of the high pressure side pipe in the internal heat exchanger of this Embodiment. It is a characteristic view which shows the passage resistance of the low voltage | pressure side pipe in the internal heat exchanger of this Embodiment. It is a characteristic view which shows the heat exchange amount in the internal heat exchanger of this Embodiment. It is a side view which shows the other example of the internal heat exchanger of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... External heat exchanger 3 ... 1st evaporator 4 ... 2nd evaporator 5 ... 1st internal heat exchanger (internal heat exchanger)
6 ... Second internal heat exchanger (internal heat exchanger)
DESCRIPTION OF SYMBOLS 9 ... 1st expansion valve 10 ... 2nd expansion valve 11 ... Solenoid valve 21 ... High pressure side pipe 22 ... Low pressure side pipe

Claims (5)

An internal heat exchange that includes a high-pressure side pipe (21) through which a high-pressure and intermediate-temperature refrigerant flows and a low-pressure side pipe (22) through which a low-pressure and low-temperature refrigerant having lower pressure and temperature flow, and performs heat exchange between these refrigerants. A vessel,
The high-pressure side pipe (21) is a circular pipe having a smaller inner diameter and outer diameter than the low-pressure side pipe (22), and the high-pressure side pipe (21) and the low-pressure side pipe (22) are close to each other in a spiral shape. An internal heat exchanger characterized by having an open structure. The internal heat exchanger according to claim 1,
An internal heat exchanger characterized in that a clad material is provided on the outer periphery of the high-pressure side pipe (21). An internal heat exchanger according to claim 1 or claim 2,
The inner diameter (φLow) of the low-pressure side pipe (22) is in the range of 8 to 12 mm in equivalent diameter, and the inner diameter (φHi) of the high-pressure side pipe (21) is in the range of 4 to 6 mm in equivalent diameter. And internal heat exchanger. An internal heat exchanger according to any one of claims 1 to 3,
An internal heat exchanger characterized in that at least two high-pressure side pipes (21) are provided. An internal heat exchanger according to any one of claims 1 to 4,
An internal heat exchanger characterized in that the refrigerant is carbon dioxide gas.

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