Heat exchanger, accumulator using the heat exchanger, and air conditioner

Abstract

To increase the heat transfer coefficient of a gas refrigerant by an unprecedented approach.SOLUTION: A heat exchanger 100 performs heat exchange between a liquid refrigerant L1 flowing inside a tube 20 and a gas refrigerant L2 flowing outside the tube 20. The heat exchanger is provided with a jetting mechanism 30 disposed outside the tube 20 and configured to jet the gas refrigerant L2 onto the tube 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heat exchanger, an accumulator using the heat exchanger, and an air conditioner.

Background Art

[0002] As a conventional heat exchanger, as shown in Patent Document 1, there is a so-called shell-and-tube heat exchanger including a shell and a plurality of tubes provided in the shell, which performs heat exchange between a refrigerant flowing inside the tubes and a refrigerant flowing outside the tubes in the shell.

[0003] When using such a heat exchanger, generally, a liquid refrigerant is made to flow inside the tubes. Thereby, compared with the case where a liquid refrigerant flows outside the tubes, the flow rate of the liquid refrigerant with a small specific volume can be increased, so that the heat transfer rate of the liquid refrigerant can be improved.

[0004] On the other hand, since a gas refrigerant with a low thermal conductivity and a low heat transfer rate flows outside the tubes, in order to further improve the heat exchange efficiency, it is necessary to improve the heat transfer rate of the gas refrigerant. For this purpose, a method of increasing the flow rate of the gas refrigerant similar to that of the liquid refrigerant can be considered. Specifically, for example, an aspect of providing an obstacle that inhibits the flow of the gas refrigerant can be mentioned.

[0005] However, since the gas refrigerant has a large specific volume and a high original flow rate, the expected effect of improving the heat transfer rate by increasing the flow rate is small. On the contrary, an increase in pressure loss is caused by the obstacle.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, the present invention has been made to solve the above-described problems, and the main object thereof is to improve the heat transfer coefficient of the gas refrigerant by an unprecedented method.

Means for Solving the Problems

[0008] That is, the heat exchanger according to the present invention is a heat exchanger that exchanges heat between a liquid refrigerant flowing inside a liquid pipe and a gas refrigerant flowing outside the liquid pipe, and is provided outside the liquid pipe and includes an injection mechanism for injecting the gas refrigerant into the liquid pipe.

[0009] According to the heat exchanger configured as described above, since the gas refrigerant is ejected by the injection mechanism, when the gas refrigerant in the form of a jet collides with the outer surface of the liquid pipe, the temperature boundary layer becomes thinner, and the heat transfer coefficient of the gas refrigerant can be dramatically improved as compared with the conventional case.

[0010] The liquid pipe further includes a shell provided inside, and the injection mechanism preferably has at least one gas pipe provided in the shell through which the gas refrigerant flows, and small holes for injecting the gas refrigerant into the gas pipe are formed. In this case, the gas refrigerant can be injected with a simple configuration.

[0011] By the way, a conventional shell-and-tube heat exchanger is configured such that the gas refrigerant flows from one side to the other side along the liquid pipe. Although the heat transfer coefficient is high on one side of the liquid pipe, the heat transfer coefficient becomes low on the other side of the liquid pipe. Therefore, it is preferable that the gas pipe extends along the liquid pipe and the small holes are formed at a plurality of locations along the liquid pipe. In this case, since the gas refrigerant can be injected over a wide range in the longitudinal direction of the liquid pipe, a heat transfer promotion effect can be obtained over the entire region of the liquid pipe.

[0012] The injection mechanism preferably has a plurality of the gas pipes. In this case, depending on the arrangement pattern of a plurality of gas pipes, the flow of the gas refrigerant injected from those gas pipes can be made uniform or, conversely, disrupted, and the heat transfer rate can be improved by accelerating the flow of the gas refrigerant.

[0013] It is preferable that the injection mechanism further includes an ejector structure that surrounds the gas pipe and has a passage opening through which the gas refrigerant injected from the small holes passes, and an intake opening that is provided separately from the passage opening and takes in the surrounding fluid. In this case, due to the ejector function exerted by the ejector structure, the gas refrigerant remaining around the gas pipe can be entrained and injected again, and the heat exchange amount can be increased.

[0014] In order to further improve the heat exchange efficiency, it is preferable to provide an extended heat transfer surface on the outer surface of the liquid pipe.

[0015] Further, the accumulator and the air conditioner according to the present invention are characterized by including the heat exchanger described above. According to such an accumulator or air conditioner, the same operational effects as those of the heat exchanger described above can be achieved.

Effects of the Invention

[0016] According to the present invention configured as described above, the heat transfer rate of the gas refrigerant can be dramatically improved as compared with the prior art, and thus the heat exchange efficiency can be significantly improved.

Brief Description of the Drawings

[0017]

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Mode for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the heat exchanger according to the present invention will be described with reference to the drawings.

[0019] The heat exchanger according to the present embodiment is used in at least one of an outdoor heat exchanger and an indoor heat exchanger in an air conditioner including a refrigerant circuit to which a compressor, an outdoor heat exchanger, a throttling mechanism, and an indoor heat exchanger are connected.

[0020] Specifically, as shown in FIG. 1, this heat exchanger 100 is a so-called shell-and-tube heat exchanger, and includes a shell 10 and a plurality of tubes 20 serving as liquid tubes provided in the shell 10, and exchanges heat between the liquid refrigerant L1 flowing in the tubes 20 and the gas refrigerant L2 flowing outside the tubes 20 in the shell 10. Note that the heat exchanger 100 of the present embodiment exchanges heat between a high-temperature liquid refrigerant and a low-temperature gas refrigerant, but may also exchange heat between a high-temperature gas refrigerant and a low-temperature liquid refrigerant. Also, here, four tubes 20 are schematically illustrated as an example, but the number of tubes 20 is not limited to this and may be appropriately changed.

[0021] The shell 10 is cylindrical. As shown in FIG. 1, in its internal space, there are provided an inflow region Si into which the liquid refrigerant L1 flows, an outflow region So from which the liquid refrigerant L1 flows out, and a heat exchange region Se through which the gas refrigerant L2 flows in and out and where heat exchange occurs between the liquid refrigerant L1 and the gas refrigerant L2. Here, the cross-section of the shell 10 perpendicular to the central axis is circular, but it may also be rectangular.

[0022] The inflow region Si is set on one axial side of the shell 10, and a first inflow port Pa for allowing the liquid refrigerant L1 to flow into the inflow region Si is provided.

[0023] The outflow region So is set on the other axial side of the shell 10, and a first outflow port Pb for allowing the liquid refrigerant L1 to flow out from the outflow region So is provided.

[0024] However, as shown in FIG. 1, the heat exchanger 100 of the present embodiment is provided outside the tube 20 in the heat exchange region Se and includes an injection mechanism 30 for injecting the gas refrigerant L2 into the tube 20. Here, the injection means generating a jet flow and giving a high flow velocity to the surrounding fluid.

[0025] More specifically, the injection mechanism 30 of the present embodiment has at least one gas pipe 31 provided in the shell 10 through which the gas refrigerant L2 flows, and small holes 30h for injecting the gas refrigerant L2 into the gas pipe 31 are formed.

[0026] This gas pipe 31 is provided in the heat exchange region Se and supplies the gas refrigerant L2 introduced into the second introduction port Pc to the heat exchange region Se. The gas pipe 31 here extends along the axial direction of the shell 10, specifically, it extends parallel to the central axis of the shell 10 and the above-mentioned tube 20. Further, this gas pipe 31 is provided at a position eccentric from the central axis of the shell 10, specifically, it is arranged so as to face the inner peripheral surface of the shell 10.

[0027] The gas refrigerant L2 supplied from this gas pipe 31 is configured to flow out from a second outflow port Pd provided in the heat exchange region Se and facing the gas pipe 31. Here, a plurality of second outflow ports Pd are arranged, for example, at equal intervals along the tube 20.

[0028] The small holes 30h jet the gas refrigerant L2 flowing in the gas pipe 31 perpendicularly to the flow direction of the liquid refrigerant L1 flowing through the tube 20 (in other words, the extending direction of the tube 20). Specifically, these small holes 30h are formed at locations on the outer peripheral surface of the gas pipe 31 that face the outer peripheral surface of at least one tube 20. Here, the small holes 30h formed at a plurality of locations are arranged along the tube 20.

[0029] These small holes 30h are, for example, 1.0 mm or more and 10.0 mm or less in diameter. In this embodiment, the small holes 30h having the same dimensions are arranged linearly in a row. However, the size of the small holes 30h may be appropriately changed, for example, to be larger or smaller on the downstream side than on the upstream side of the gas refrigerant L2 flowing through the gas pipe 31. Also, the arrangement of the small holes 30h is not limited to a linear arrangement in a single row, and may be arranged, for example, in two or more rows or in a staggered pattern.

[0030] According to the heat exchanger 100 of this embodiment configured as described above, since the gas refrigerant L2 is ejected by the ejection mechanism 30, when the jet flow of the gas refrigerant L2 collides with the outer surface of the liquid pipe, the temperature boundary layer becomes thinner, and the heat transfer coefficient of the gas refrigerant L2 can be dramatically improved compared to the conventional case. Here, in order to fully obtain the above-described effects by ejecting the gas refrigerant L2, it is preferable that the flow velocity of the ejected gas refrigerant L2 be 3 m / s or more. On the other hand, if the flow velocity is too large, the pressure loss increases. Therefore, it is desirable to keep the flow velocity of the ejected gas refrigerant L2 at 10 m / s or less. In contrast, since the small hole 30h of the present embodiment has a diameter of 1.0 mm or more and 10.0 mm or less as described above, the flow velocity of the gas refrigerant ejected from the small hole 30h can be set to 3 to 10 m / s. Thereby, while suppressing an increase in pressure loss, a dramatic improvement in the heat transfer coefficient of the gas refrigerant L2 can be achieved.

[0031] Further, since the gas pipe 31 extends along the tube 20 and a plurality of small holes 30h are formed in this gas pipe 31 along the liquid pipe, the gas refrigerant L2 can be injected over a wide range in the longitudinal direction of the tube 20, and a heat transfer promotion effect in the entire region of the tube 20 can be obtained.

[0032] Note that the present invention is not limited to the above-described embodiment.

[0033] For example, in the above-described embodiment, there were four tubes 20, but as shown in FIG. 3, a large number of tubes 20 may be densely arranged in the shell 10. In this case, at least a part of the gas refrigerant L2 ejected by the injection mechanism 30 flows while circulating along the inner wall surface of the shell 10.

[0034] Further, the injection mechanism 30 of the above-described embodiment had one gas pipe 31, but as shown in FIGS. 4 to 6, it may have a plurality of gas pipes 31.

[0035] Specifically, as shown in FIG. 4, a plurality of gas pipes 31 are arranged outside the plurality of tubes 20, and the injection directions of the gas refrigerant L2 ejected from these gas pipes 31 may be configured to be parallel to each other. Also, as shown in FIGS. 5 and 6, a plurality of gas pipes 31 may be arranged outside the plurality of tubes 20, and the injection directions of the gas refrigerant L2 injected from these gas pipes 31 may be configured to face each other. With such a configuration, depending on the arrangement mode of the plurality of gas pipes 31, the flow of the gas refrigerant L2 injected from these gas pipes 31 can be made uniform or, conversely, disrupted, and the heat transfer rate can also be improved by accelerating the flow of the gas refrigerant L2.

[0036] Furthermore, as shown in FIG. 7, the gas pipe 31 may be arranged at the center of the shell 10. In this case, the small holes 30h are preferably arranged at equal intervals, for example, in the axial direction of the gas pipe 31 and also at equal intervals, for example, in the circumferential direction of the gas pipe 31. In this way, the gas refrigerant L2 can be injected from a preferably small number of gas pipes 31 toward a large number of tubes 20, and the heat transfer rate can be improved without increasing the size or cost of the heat exchanger 100.

[0037] Also, as an injection mechanism 30, as shown in FIG. 8, an ejector structure surrounding the gas pipe 31 may be provided. More specifically, this ejector mechanism 40 has a passage port 40a through which the gas refrigerant L2 injected from the small holes 30h passes, and a suction port 40b provided separately from the passage port 40a for taking in the surrounding fluid, and is configured such that when the gas refrigerant L2 passes through the passage port 40a, a negative pressure is generated around the suction port 40b. In this way, due to the ejector function exerted by the ejector structure, the gas refrigerant L2 remaining around the gas pipe 31 can be entrained and injected again, and the heat exchange amount can be increased.

[0038] Furthermore, as the heat exchanger 100 according to the present invention, as shown in FIG. 9, in the heat exchange region Se, an extended heat transfer surface 50 provided on the outer surface of the tube 20 may be provided. This enlarged heat transfer surface 50 is formed by fins provided on the outer peripheral surface of the tube 20, and here, a plurality of fins are provided along the longitudinal direction of the tube 20. With such a configuration, since the enlarged heat transfer surface 50 is provided on the tube 20, further improvement in the heat exchange efficiency in the heat exchange region Se can be achieved.

[0039] Further, as shown in FIG. 10, the heat exchanger 100 according to the present invention may be incorporated in the accumulator A. Since the low-temperature refrigerant inside the accumulator A is mainly the gas refrigerant L2, by using the heat exchanger 100 according to the present invention, the high-temperature refrigerant can be cooled by using the low-temperature refrigerant inside the accumulator A. Thereby, the heat transfer area can be reduced, and low-cost and high-efficiency cold heat recovery becomes possible. Furthermore, even under the condition that a large amount of the liquid refrigerant L1 flows into the accumulator A, by using the heat exchanger 100 according to the present invention, the liquid refrigerant L1 can be heated and evaporated, so that the outflow amount of the liquid refrigerant L1 from the accumulator A can be suppressed, which also leads to ensuring the reliability of the compressor.

[0040] Furthermore, as the heat exchanger 100 according to the present invention, as shown in FIG. 11, as long as it includes a liquid pipe through which the liquid refrigerant L1 flows and an injection mechanism 30 for injecting the gas refrigerant L2 into this liquid pipe, it does not necessarily need to include the shell 10.

[0041] Needless to say, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit thereof.

Description of Reference Numerals

[0042] 100 ··· Heat exchanger L1 ··· Liquid refrigerant L2 ··· Gas refrigerant 10 ··· Shell 20 ··· Tube (liquid pipe) 30 ··· Injection mechanism 31 ··· Gas pipe 30h ··· Small hole 40 ··· Ejector mechanism 50 ··· Extended heat transfer surface

Claims

Claim 1 A heat exchanger that exchanges heat between a liquid refrigerant flowing inside a liquid pipe and a gas refrigerant flowing outside the liquid pipe, comprising a shell provided inside the liquid pipe, and an injection mechanism provided outside the liquid pipe for injecting the gas refrigerant into the liquid pipe, wherein the injection mechanism further comprises an ejector structure having at least one gas pipe provided in the shell through which the gas refrigerant flows, a passage port surrounding the gas pipe and allowing the gas refrigerant injected from small holes formed in the gas pipe to pass through, and an intake port provided separately from the passage port for taking in surrounding fluid. Claim 2 The heat exchanger according to claim 1, wherein the gas pipe extends along the liquid pipe, and the small holes are formed at a plurality of locations along the liquid pipe. Claim 3 The heat exchanger according to claim 1 or 2, wherein the injection mechanism has a plurality of the gas pipes. Claim 4 The heat exchanger according to any one of claims 1 to 3, further comprising an enlarged heat transfer surface provided on an outer surface of the liquid pipe. Claim 5 An accumulator comprising the heat exchanger according to any one of claims 1 to 4. Claim 6 An air conditioner comprising the heat exchanger according to any one of claims 1 to 4.

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