JP7712124B2 - Heat exchanger, and accumulator and air conditioner using said heat exchanger - Google Patents

Description

The present invention relates to a heat exchanger and an accumulator and an air conditioner that use this heat exchanger.

As shown in Patent Document 1, a conventional heat exchanger is a so-called shell-and-tube heat exchanger that has a shell and multiple tubes provided within the shell, and exchanges heat between the refrigerant flowing inside the tubes and the refrigerant flowing outside the tubes within the shell.

When using such a heat exchanger, the liquid refrigerant is generally made to flow inside the tubes. This allows the flow rate of the liquid refrigerant, which has a small specific volume, to be increased compared to when the liquid refrigerant flows on the outside of the tubes, making it possible to improve the heat transfer coefficient of the liquid refrigerant.

On the other hand, since gas refrigerant with low thermal conductivity and low heat transfer rate flows on the outside of the tube, it is necessary to improve the heat transfer rate of the gas refrigerant in order to further improve the heat exchange efficiency. To achieve this, it is possible to consider a method of increasing the flow rate of the gas refrigerant, just like with liquid refrigerant. Specifically, for example, one option is to provide an obstacle that obstructs the flow of the gas refrigerant.

However, because gas refrigerants have a large specific volume and an inherently fast flow rate, increasing the flow rate is unlikely to improve the heat transfer coefficient, and instead will result in increased pressure loss due to obstacles.

JP 2009-174780 A

Therefore, the present invention was made to solve the above-mentioned problems, and its main objective is to improve the heat transfer coefficient of gas refrigerant using an unprecedented method.

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 characterized by having an injection mechanism that is provided outside the liquid pipe and injects the gas refrigerant into the liquid pipe.

In a heat exchanger configured in this way, the gas refrigerant is ejected by the injection mechanism, so that when the jet of gas refrigerant 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 compared to conventional methods.

It is preferable that the cooling system further includes a shell having the liquid pipe provided therein, the injection mechanism having at least one gas pipe provided within the shell through which the gas refrigerant flows, and a small hole for injecting the gas refrigerant is formed in the gas pipe.
In this case, the gas refrigerant can be sprayed with a simple configuration.

Conventional shell-and-tube heat exchangers are configured so that a gas refrigerant flows from one side to the other along a liquid pipe, and while the heat transfer coefficient is high on one side of the liquid pipe, the heat transfer coefficient is low on the other side of the liquid pipe.
Therefore, it is preferable that the gas pipe extends along the liquid pipe, and that the small holes are formed at a plurality of locations along the liquid pipe.
In this case, the gas refrigerant can be sprayed over a wide area in the longitudinal direction of the liquid pipe, thereby achieving the effect of promoting heat transfer over the entire area of the liquid pipe.

It is preferable that the injection mechanism has a plurality of the gas pipes.
In this case, depending on the arrangement of the multiple gas pipes, the flow of the gas refrigerant sprayed from the gas pipes can be made uniform or, conversely, disturbed, and the heat transfer coefficient can be improved by accelerating the flow of the gas refrigerant.

It is preferable that the injection mechanism further comprises an ejector structure that surrounds the gas pipe and has a passage port through which the gas refrigerant injected from the small hole passes, and an intake port provided separately from the passage port for taking in surrounding fluid.
In this case, the ejector function exerted by the ejector structure can entrain and re-eject the gas refrigerant remaining around the gas pipe, thereby increasing the amount of heat exchange.

To further improve the heat exchange efficiency, it is preferable to provide an extended heat transfer surface on the outer surface of the liquid tube.

The accumulator and air conditioner according to the present invention are characterized by being equipped with the above-mentioned heat exchanger, and such an accumulator and air conditioner can achieve the same effects as the above-mentioned heat exchanger.

The present invention, configured in this way, can dramatically improve the heat transfer coefficient of the gas refrigerant compared to conventional methods, and therefore can greatly improve the heat exchange efficiency.

FIG. 2 is a schematic diagram showing the configuration of a heat exchanger in the present embodiment. FIG. 2 is a schematic diagram showing the configuration of a heat exchanger in the embodiment. FIG. 11 is a schematic diagram showing a configuration of a heat exchanger according to another embodiment. FIG. 11 is a schematic diagram showing a configuration of a heat exchanger according to another embodiment. FIG. 11 is a schematic diagram showing a configuration of a heat exchanger according to another embodiment. FIG. 11 is a schematic diagram showing a configuration of a heat exchanger according to another embodiment. FIG. 11 is a schematic diagram showing a configuration of a heat exchanger according to another embodiment. FIG. 11 is a schematic diagram showing a configuration of an ejector structure according to another embodiment. FIG. 13 is a schematic diagram showing a configuration of a heat transfer expansion surface in another embodiment. FIG. 11 is a schematic diagram showing an internal configuration of an accumulator according to another embodiment. FIG. 11 is a schematic diagram showing a configuration of a heat exchanger according to another embodiment.

Below, one embodiment of the heat exchanger according to the present invention will be described with reference to the drawings.

The heat exchanger according to this embodiment is used as at least one of the outdoor heat exchanger or the indoor heat exchanger in an air conditioner having a refrigerant circuit to which a compressor, an outdoor heat exchanger, a throttling mechanism, and an indoor heat exchanger are connected.

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

The shell 10 is cylindrical, and as shown in FIG. 1, its internal space is provided with an inflow area Si into which the liquid refrigerant L1 flows, an outflow area So from which the liquid refrigerant L1 flows out, and a heat exchange area Se into which the gas refrigerant L2 flows in and out and where heat exchange takes place between the liquid refrigerant L1 and the gas refrigerant L2. Note that, although the cross section of the shell 10 perpendicular to the central axis is circular here, the cross section may be rectangular.

The inlet region Si is set on one axial side of the shell 10, and a first inlet port Pa is provided to allow the liquid refrigerant L1 to flow into this inlet region Si.

The outflow area So is set on the other axial side of the shell 10, and a first outflow port Pb is provided to allow the liquid refrigerant L1 to flow out of this outflow area So.

As shown in FIG. 1, the heat exchanger 100 of this embodiment includes an injection mechanism 30 that is provided outside the tubes 20 in the heat exchange area Se and that injects a gas refrigerant L2 onto the tubes 20. As shown in FIG.
The term "jet" used herein means to generate a jet flow and to impart a high flow velocity to the surrounding fluid.

More specifically, the injection mechanism 30 of this embodiment has at least one gas pipe 31 that is provided inside the shell 10 and through which the gas refrigerant L2 flows, and this gas pipe 31 has a small hole 30h formed therein for injecting the gas refrigerant L2.

This gas pipe 31 is provided in the heat exchange area Se, and supplies the gas refrigerant L2 introduced into the second inlet port Pc to the heat exchange area Se. The gas pipe 31 here extends along the axial direction of the shell 10, specifically, parallel to the central axis of the shell 10 and the above-mentioned tube 20. In addition, this gas pipe 31 is provided at a position eccentric to the central axis of the shell 10, specifically, arranged so as to face the inner circumferential surface of the shell 10.

The gas refrigerant L2 supplied from the gas pipe 31 is configured to flow out from a second outlet port Pd provided in the heat exchange area Se and facing the gas pipe 31, and here, multiple second outlet ports Pd are arranged, for example, at equal intervals along the tube 20.

The small holes 30h are used to spray the gas refrigerant L2 flowing inside the gas pipe 31 perpendicular to the flow direction of the liquid refrigerant L1 flowing through the tube 20 (in other words, the extension direction of the tube 20). Specifically, the small holes 30h are formed on the outer circumferential surface of the gas pipe 31 at locations directly facing the outer circumferential surface of at least one tube 20, and here the small holes 30h formed at multiple locations are arranged along the tube 20.

These small holes 30h have a diameter of, for example, 1.0 mm to 10.0 mm, and in this embodiment, small holes 30h of the same size are arranged in a single linear row. However, the size of the small holes 30h may be changed as appropriate, for example, by making the small holes 30h larger or smaller on the downstream side than on the upstream side of the gas refrigerant L2 flowing through the gas pipe 31. In addition, the arrangement of the small holes 30h is not limited to a single linear row, and they may be arranged in, for example, two or more rows, or in a staggered pattern.

According to the heat exchanger 100 of this embodiment configured in this manner, the gas refrigerant L2 is ejected by the injection mechanism 30, so that when the jet of 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 art.
Here, in order to fully obtain the above-mentioned action and effect by ejecting the gas refrigerant L2, it is preferable that the flow velocity of the ejected gas refrigerant L2 is 3 m/s or more. On the other hand, if the flow velocity is too high, pressure loss increases, so it is desirable to suppress the flow velocity of the ejected gas refrigerant L2 to 10 m/s or less. In contrast, since the small holes 30h of this embodiment have 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 these small holes 30h can be set to 3 to 10 m/s. This makes it possible to dramatically improve the heat transfer coefficient of the gas refrigerant L2 while suppressing an increase in pressure loss.

In addition, the gas pipe 31 extends along the tube 20, and multiple small holes 30h are formed in the gas pipe 31 along the liquid pipe, so that the gas refrigerant L2 can be sprayed over a wide area in the longitudinal direction of the tube 20, and the heat transfer promotion effect is obtained in the entire area of the tube 20.

The present invention is not limited to the above embodiment.

For example, in the above embodiment, there are four tubes 20, but as shown in FIG. 3, a large number of tubes 20 may be densely arranged inside the shell 10.
In this case, at least a portion of the gas refrigerant L2 injected by the injection mechanism 30 flows while circulating along the inner wall surface of the shell 10.

In addition, although the injection mechanism 30 in the above embodiment has one gas pipe 31, it may have multiple gas pipes 31 as shown in Figures 4 to 6.

Specifically, as shown in FIG. 4, a plurality of gas pipes 31 are arranged outside a plurality of tubes 20, and the directions of the gas refrigerant L2 sprayed from these gas pipes 31 may be configured to be parallel to each other.
Also, as shown in Figures 5 and 6, a plurality of gas pipes 31 may be arranged outside a plurality of tubes 20, and the directions of the gas refrigerant L2 sprayed from these gas pipes 31 may be configured to face each other.
With this configuration, depending on the arrangement of the multiple gas pipes 31, the flow of the gas refrigerant L2 sprayed from those gas pipes 31 can be made uniform or, conversely, disturbed, and the heat transfer coefficient can be improved by accelerating the flow of the gas refrigerant L2.

7, the gas pipe 31 may be disposed in the center of the shell 10. In this case, it is preferable that the small holes 30h are disposed, for example, at equal intervals in the axial direction of the gas pipe 31 and, for example, at equal intervals in the circumferential direction of the gas pipe 31.
In this way, the gas refrigerant L2 can be sprayed toward a large number of tubes 20 from as few gas pipes 31 as possible, thereby improving the heat transfer coefficient without increasing the size or cost of the heat exchanger 100.

Moreover, the injection mechanism 30 may have an ejector structure surrounding a gas pipe 31 as shown in FIG.
More specifically, the ejector mechanism 40 has a passage port 40a through which the gas refrigerant L2 sprayed from the small hole 30h passes, and an intake port 40b provided separately from the passage port 40a and which takes in the surrounding fluid, and is configured so that negative pressure is generated around the intake port 40b when the gas refrigerant L2 passes through the passage port 40a.
In this case, the ejector function exerted by the ejector structure can entrain and eject the gas refrigerant L2 remaining around the gas pipe 31 again, thereby increasing the amount of heat exchange.

Furthermore, the heat exchanger 100 according to the present invention may include an extended heat transfer surface 50 provided on the outer surface of the tube 20 in the heat exchange region Se, as shown in FIG.
The extended heat transfer surface 50 is formed by fins provided on the outer circumferential surface of the tube 20 , and here a plurality of fins are provided along the longitudinal direction of the tube 20 .
In this configuration, since the tubes 20 are provided with the enlarged heat transfer surfaces 50, the heat exchange efficiency in the heat exchange area Se can be further improved.

Moreover, the heat exchanger 100 according to the present invention may be incorporated into an accumulator A as shown in FIG.
Since the low-temperature refrigerant inside the accumulator A is mainly gas refrigerant L2, by using the heat exchanger 100 according to the present invention, the high-temperature refrigerant can be cooled by utilizing the low-temperature refrigerant inside the accumulator A. This makes it possible to reduce the heat transfer area, enabling low-cost and highly efficient cold heat recovery.
Furthermore, even under conditions in which a large amount of liquid refrigerant L1 flows into the accumulator A, by utilizing the heat exchanger 100 according to the present invention, the liquid refrigerant L1 can be heated and evaporated, thereby reducing the amount of liquid refrigerant L1 flowing out of the accumulator A, which also ensures the reliability of the compressor.

Furthermore, as shown in FIG. 11, the heat exchanger 100 according to the present invention does not necessarily need to include a shell 10, so long as it is equipped with a liquid pipe through which liquid refrigerant L1 flows and an injection mechanism 30 that injects gas refrigerant L2 into the liquid pipe.

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the invention.

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: Enlarged heat transfer surface

Claims (6)

A heat exchanger that exchanges heat between a liquid refrigerant flowing inside a liquid pipe and a gas refrigerant flowing outside the liquid pipe,
a shell having the liquid pipe provided therein;
an injection mechanism provided outside the liquid pipe and configured to inject the gas refrigerant into the liquid pipe ;
the injection mechanism further comprises an ejector structure having at least one gas pipe provided in the shell and through which the gas refrigerant flows, an outlet surrounding the gas pipe and allowing the gas refrigerant injected from a small hole formed in the gas pipe to pass through, and an inlet provided separately from the outlet and taking in a surrounding fluid . 2. The heat exchanger of 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. 3. The heat exchanger according to claim 1 , wherein the injection mechanism has a plurality of the gas pipes. The heat exchanger according to claim 1 , further comprising an extended heat transfer surface provided on an outer surface of the liquid pipe. An accumulator comprising a heat exchanger according to any one of claims 1 to 4 . An air conditioner comprising the heat exchanger according to any one of claims 1 to 4 .