JP2677420B2 - Heat exchanger for refrigerant condenser - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air conditioner, and more particularly to a heat exchanger for a condenser of a car air conditioner, and is particularly suitable for saving the amount of refrigerant charged in a refrigeration cycle. The present invention relates to a heat exchanger for a condenser.

[Prior Art] A conventional heat exchanger as a refrigerant condenser for a car air conditioner includes a corrugated fin that is bent in a corrugated shape and a large number of heat transfer tubes having a plurality of refrigerant passages alternately stacked to form a heat exchange core. Many of them have a structure in which both ends of the heat transfer tube are connected to header pipes and the flow of the refrigerant gas in the tube is guided at the heat transfer tube inlet and outlet.

These heat transfer tubes are divided into two or more tube groups each composed of a plurality of heat transfer tubes by a partition plate provided in the header pipe, and the refrigerant is made to meander and flow into these tube groups. Japanese Patent Laid-Open No. 63-3446 discloses a structure in which the passage cross-sectional area of a group is reduced from the inlet side toward the outlet side. In addition, a configuration in which the cross-sectional shape and cross-sectional area of the heat transfer tubes are changed for each divided tube group is the actual exploitation Sho 63-1736.
89. By providing a central partition body along the longitudinal direction in the header and also providing a central partition body in the heat transfer tube that divides the internal passage into a front passage and a rear passage, the refrigerant passages are divided into a front passage group and a rear passage group. A structure divided into two is disclosed in JP-A-63-3191. In addition, a plurality of tube groups with different lengths are connected to the same header pipe with one end aligned for each group, and the other end is connected to a plurality of header pipes for each tube group to form a recess due to the withdrawal of the header. The structure described above is disclosed in Japanese Utility Model Laid-Open No. 63-74989. Other related condensers of this type include, for example, SAIKAI Sho 63-22566, SHIKAI Sho 63-74970, and SAIKAI Sho 63-80.
492 and J. Kaikai 64-31369.

Generally, in an air conditioner such as a car air conditioner where the inside and outside air conditions and the number of revolutions of the compressor vary widely, it is necessary to make the amount of the refrigerant filled a little excessive so as to cope with it, and store the excess amount of the refrigerant in the liquid tank. It is normal.

[Problems to be Solved by the Invention] In the heat exchanger for a condenser of the type described above, the two-phase refrigerant of the liquid and the gas flowing out from the intermediate pipe line group composed of a plurality of heat transfer pipes is the outlet pipe line inlet. The end flows into the outlet pipe inlet header part connected so that the intermediate pipe line group outlet end communicates with the end. Due to the action of gravity and the centrifugal force when the flow bends, a large amount of the liquid refrigerant gathers at the end of the header, and the liquid refrigerant and the gas refrigerant are separated in the header.

However, in each of the above-mentioned conventional condensers, the refrigerant outlet side conduit group is composed of a plurality of heat transfer tubes. Therefore, in such a conventional condenser, in the plurality of heat transfer tubes of the outlet side pipe line group, a large amount of liquid refrigerant flows in a certain heat transfer tube among them, depending on the position, in a certain heat transfer tube gas. Non-uniform distribution of the refrigerant occurs because a large amount of the refrigerant flows.Therefore, the condensation of the refrigerant becomes insufficient in the heat transfer tube where a large amount of the gas refrigerant flows, and the refrigerant flows out of the heat transfer tube outlet without being condensed, and in the liquid refrigerant in the outlet header part. To produce air bubbles.
In this way, the gas refrigerant that could not be condensed due to the non-uniform distribution of the refrigerant comes out of the condenser outlet mixed with the liquid refrigerant.
When the liquid refrigerant mixed with the gas refrigerant is passed through the expansion valve, the mass flow rate of the refrigerant changes greatly depending on the mixing degree of the gas refrigerant, the operation of the expansion valve becomes unstable, and the refrigeration cycle becomes unstable. However, conventionally, even if the gas refrigerant is mixed with the liquid refrigerant at the condenser outlet, this is once introduced into the liquid tank,
Since the refrigerant after passing through the liquid tank is passed through the expansion valve, the problem of unstable operation of the expansion valve as described above has been prevented.

By the way, recently, in order to protect the earth, efforts have been made to reduce the amount of refrigerant filled in the refrigeration cycle as much as possible, and it is considered to omit the liquid tank. However, if the liquid tank is omitted, in the conventional condenser, the liquid refrigerant mixed with the gas refrigerant will pass through the expansion valve for the above-mentioned reason, which makes the operation of the expansion valve unstable and the refrigeration cycle unstable. There is a problem that it will end up. In order to stabilize the operation of the expansion valve, generally, the subcool amount at the condenser outlet should be about 5 ° C, but in the case of an air conditioner such as a car air conditioner where the inside and outside air conditions and the compressor rotation speed change greatly. In order to secure a sub-cooling amount under all operating conditions, the amount of refrigerant to be enclosed in the refrigeration cycle must be increased, and it is not possible to meet the demand for reducing the amount of refrigerant to be enclosed as much as possible.

INDUSTRIAL APPLICABILITY The present invention makes it possible to prevent gas refrigerant from being mixed into liquid refrigerant at the condenser outlet as much as possible, and further, is suitable for reducing the amount of refrigerant to be sealed in the refrigeration cycle. The purpose is to provide.

[Means for Solving the Problems] The heat exchanger for a refrigerant condenser according to the present invention has the configuration described in the claims.

[Operation] In the heat exchanger for a refrigerant condenser according to the present invention, the outlet side pipeline is composed of one heat transfer tube, so that the gas refrigerant and the liquid refrigerant uniformly flow into the outlet side conduit, and the conventional problems are Does not happen.
That is, if the outlet side pipeline is composed of a plurality of heat transfer tubes as in the conventional case, the mixing ratio of the liquid refrigerant and the gas refrigerant is different in each heat transfer tube, but in the present invention, the outlet side pipeline is one. The above-mentioned problem does not occur because the heat transfer tubes are used. In the present invention, since the number of outlet side pipelines is one, when the mixing ratio of the gas refrigerant increases, the pressure drop in the pipelines increases, therefore the pressure on the upstream side rises, and therefore the condensation temperature rises, and the refrigerant , The temperature difference between the cooling air and the cooling air increases, the amount of heat radiation increases, and as a result, the proportion of liquid refrigerant increases and the proportion of gas refrigerant decreases.
Self-controllability occurs. Therefore, the proportion of the liquid refrigerant in the refrigerant at the outlet of the condenser can be made larger than that of the condenser in which the outlet side pipeline is composed of a plurality of heat transfer tubes as in the related art.

An increase in pressure loss in the refrigerant passage can be prevented by making the thickness of the heat transfer pipe forming the outlet side pipe larger than that of the other heat transfer pipes and ensuring a cross-sectional area of the pipe passage.

Further, by configuring the equivalent diameter of the passage in the heat transfer tube located on the downstream side of the air where the temperature difference between the refrigerant and air is small and the amount of heat exchanged is small, the passage resistance increases there, and the refrigerant flow rate is commensurate with the amount of exchange heat. Since it decreases, the heat exchange efficiency can be improved as a whole.

[Examples] A first example of the present invention will be described below with reference to FIGS. 1 and 2. A plurality of heat transfer tubes 1 and a plurality of corrugated fins 2 formed into a corrugated shape are alternately laminated to form a heat exchange section core. Headers 3 and 4 are connected to both ends of the heat transfer tube. Partition plates 5 and 6 are provided in the header to divide the heat transfer tube 1 into a plurality of tube groups A and B and an outlet pipe line C. The tube group A is called an inlet side tube group, and the tube group B is called an intermediate tube group. The outside of the outlet conduit C is the side plate 12
It is composed of one heat transfer tube 1 with side fins 2'fixed at.

The heat transfer tube 1 is a multi-hole flat tube made of aluminum and has a plurality of rectangular flow paths inside. An electric resistance welded tube having inner fins inserted therein may be used as the heat transfer tube. The corrugated fin 2 is formed by bending an aluminum plate material having a plate thickness of about 0.1 mm into a corrugated shape, and the width in the air flow direction (direction perpendicular to the paper surface of FIG. 1) is almost the same as that of the heat transfer tube 1. It is joined to the heat transfer tube 1.

The headers 3 and 4 are circular tubes made of aluminum having a large number of flat holes spaced apart from each other in the longitudinal direction, and the heat transfer tube 1 is inserted into these holes.
Is inserted and firmly joined by brazing.
The partition plates 5 and 6 provided in the header divide the headers 3 and 4 into two chambers 3a and 3b and 4a and 4b, respectively. Also,
By providing the partition plates 5 and 6, the refrigerant pipe line group including the heat transfer pipes 1 is divided into the inlet side pipe line A, the intermediate pipe line group B, and the outlet side pipe line C, and flows from the inlet pipe 7. The refrigerant is the inlet header chamber 3a, the inlet side pipe group A, the header chamber 4a, the intermediate pipe group B, the header chamber 3b, the outlet side pipe line C, the outlet header chamber 4b.
It flows meandering in this order and flows out from the outlet pipe 8. The ends of the header pipes 3 and 4 are discs 9 and 1 respectively.
It is sealed by 0, and an inlet pipe 7 and an outlet pipe 8 are connected to the other ends, respectively.

In the above structure, the high temperature gas refrigerant flowing in from the inlet pipe 7 passes through the inlet header chamber 3a and the inlet side heat transfer tube group A.
Flowing in, the heat is exchanged with the cooling air having a low temperature, the temperature is lowered, and finally a part of the gas refrigerant starts to be condensed and liquefied. The refrigerant that has flown into the heat transfer tube group B through the header chamber 4a while reducing the ratio of the gas refrigerant is further condensed and liquefied in the tube group B, and the comparison of the liquid refrigerant is increased to the header chamber 3b. Really
Here, the gas refrigerant and the liquid refrigerant are uniformly mixed and flow into the outlet side pipe line C connected thereto. In the heat transfer tube 1 forming the outlet side conduit C, the mass velocity of the refrigerant is large, so that the heat transfer coefficient is high, and since the side fins 2'are attached to the outside of the heat transfer tube, the discharge per unit temperature difference. There is a lot of heat. Therefore, condensation and liquefaction of the gas refrigerant and supercooling are efficiently performed, and the liquid refrigerant flows out of the outlet pipe 8 through the outlet header chamber 4b. Since the refrigerant flowing in the outlet side conduit C has a small volume of about 1/30, which is smaller than that of the gas refrigerant, the volume is small. Therefore, the passage cross-sectional area is also smaller than that of the pipe groups A and B. It can be smaller than that. In this embodiment, accordingly, the heat transfer tube of the outlet pipe C is configured to be one, so that the waste of the space in the supercooling region can be omitted.

A second embodiment according to the present invention will be described with reference to FIGS. The difference from the first embodiment is that the heat transfer tube is
This is a point that two types of heat transfer tubes are used, a first type heat transfer tube 1a having a small thickness (a thickness in a direction in which the fin 2 is contacted in this embodiment) and a second type heat transfer tube 1b having a large thickness. . The heat transfer tube 1a is used to configure the inlet side tube group A and the intermediate tube group B, and the heat transfer tube 1b having a larger thickness than the heat transfer tube 1a is used to configure the outlet side tube line C. . Here, the heat transfer tubes 1a and 1b are aluminum multi-hole flat tubes, have a plurality of rectangular flow paths inside, and the heat transfer tube 1b has a larger cross-sectional area of the pipe passage.
An electric resistance welded tube having inner fins inserted therein may be used as the heat transfer tube.

Incidentally, in FIGS. 3 and 4, the same reference numerals as those in FIG.

According to the above configuration, the passage cross-sectional area in the outlet conduit C can be made larger than that in the first embodiment, so that the pressure loss can be further reduced. Other functions and effects are the same as those of the first embodiment.

A third embodiment according to the present invention will be described with reference to FIG.
This embodiment is different from the second embodiment in that the intermediate tube group B is also composed of a second type heat transfer tube 1b having a large tube thickness like the outlet side conduit C. Further, the passage cross-sectional area is largest in the inlet side pipe group A, and becomes smaller in the order of the intermediate portion pipe group B and the outlet side pipe line C. In the above structure, the high temperature gas refrigerant flowing in from the inlet pipe 7 flows into the inlet side pipe group A through the inlet header chamber 3a, exchanges heat with the cooling air having a low temperature, and eventually the temperature partially decreases. The gas refrigerant starts to condense and liquefy. The refrigerant flowing down the pipe while further reducing the ratio of the gas refrigerant flows into the intermediate tube group B composed of a plurality of second type heat transfer tubes 1b through the header chamber 4a. Tube group B
The condensation and liquefaction further progresses in the inside, and the ratio of the liquid refrigerant is increased to reach the inside of the header chamber 3b, where the gas refrigerant and the liquid refrigerant are uniformly mixed, and the second type heat transfer tube 1b connected to this. It flows into the outlet side pipe line C consisting of one line.

Here, the volume of the liquid refrigerant is about 1/30 of that of the gas refrigerant, and the volume of the in-tube refrigerant becomes smaller in the order of the tube groups A, B, and C. In this embodiment, the passage cross-sectional area of the pipe group A, which corresponds to the volume of the refrigerant in the pipe,
B and the pipeline C are set to be smaller in this order. Therefore,
Since the mass velocity of the refrigerant in the pipe is appropriately maintained and a high heat transfer coefficient can be obtained while suppressing the pressure loss, the condensation and liquefaction of the gas refrigerant and the supercooling are efficiently performed, and the outlet is passed through the outlet header chamber 4b. The liquid refrigerant flows out from the pipe 8.

A fourth embodiment according to the present invention will be described with reference to FIG.
In the present embodiment, inner fins 201 are provided in the pipe refrigerant passage 200 located on the air outlet side of the heat transfer pipe 1 in the first to third embodiments, and the equivalent diameter of the refrigerant passage 200 is located on the air upstream side. The cooling medium passage 100 is smaller than the cooling medium passage 100.
Such an in-pipe passage structure is applied to at least the heat transfer tubes forming the outlet side conduit C, and is also applied to the heat transfer tubes forming other tube groups as necessary.

The gas refrigerant in the heat transfer tube is cooled by air to release latent heat of condensation and liquefy. At this time, the temperature in the pipe is substantially constant, but the temperature of the cooling air rises from the upstream side to the downstream side, so the temperature difference between the air and the refrigerant in the pipe is large on the upstream side of the air and small on the downstream side. . In response to this, in this embodiment, the equivalent diameter of the heat transfer tube internal passage located on the downstream side of the air with a small temperature difference from the air and a small amount of heat exchange is configured. For this reason, the passage resistance of the in-pipe passage located on the downstream side of the air increases, and the refrigerant flow rate decreases in proportion to the heat exchange amount. Therefore, the heat exchange efficiency is improved as a whole,
Condensation and liquefaction and supercooling of the gas refrigerant are performed more efficiently. Other functions and effects are the same as those of the first to third embodiments.

In the above embodiments, the condenser of the type in which the refrigerant is meandered twice by providing the outlet side pipe line in addition to the two passage groups of the inlet side pipe group and the intermediate portion pipe group is shown. The present invention is also applicable to a one-time meandering type condenser having only an inlet-side tube group and an outlet-side tube line, or a meandering-type condenser in which the middle section tube group is divided into two or more tube groups and meandering three or more times. Further, in the present embodiment, inconvenience of the refrigerant distribution in the conventional outlet pipe group caused by gravity or centrifugal force when the fluid bends and flows in the header pipe, the problem of the refrigerant distribution in the conventional outlet pipe group is This is prevented by the heat transfer tube. Therefore, it goes without saying that the effect of the present invention does not change even if the heat transfer tubes are arranged horizontally or vertically.

[Advantages of the Invention] According to the present invention, it is possible to omit the liquid tank and save the refrigerant filling amount of the refrigeration cycle as much as possible, and moreover, the refrigerant distribution of the plurality of outlet side heat transfer tubes is uneven as in the prior art. There is no problem due to, the mixture of the gas refrigerant into the liquid refrigerant at the outlet of the condenser is reduced as much as possible, the condensation and liquefaction of the gas refrigerant, supercooling is performed efficiently, the operation of the expansion valve is stabilized,
It is possible to stabilize the refrigeration cycle. Moreover, there is an advantage that such an effect is hardly influenced by the arrangement angle of the condenser.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of the present invention, FIG. 2 is a perspective view showing a joint between a header and a heat transfer tube of the same embodiment, and FIG. 3 is a front view of a second embodiment of the present invention. FIG. 4 is a perspective view of a main part of FIG. 3, FIG. 5 is a front view of a third embodiment of the present invention, and FIG. 6 is a view showing a cross section of a heat transfer tube in a fourth embodiment of the present invention. is there. 1 ... Heat transfer tube, 2 ... Corrugated fins 3,4 ... Header, A ... Inlet side tube group B ... Middle section tube group, C ... Exit line 5,6 ... Partition plate, 7 ... Inlet pipe 8 ... Outlet pipe

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takatomo Sawahata 2520 Takaba, Takada, Ibaraki Pref., Sawa Plant, Hitachi, Ltd. (56) References JP-A-2-293595 (JP, A) JP-A-2-140570 (JP, A) Actually open 2-140184 (JP, U) Actually open 2- 45359 (JP, U)

Claims (7)

(57) [Claims] 1. A refrigerant passage is formed by connecting at least both ends of a heat transfer tube constituting an outlet side conduit and an inlet side conduit to a header having a divided header chamber, and each heat transfer tube is provided with heat radiation for heat dissipation. In a heat exchanger for a refrigerant condenser, which is configured such that the fins are coupled and the refrigerant meanders through the header chamber, the inlet side conduit and the outlet side conduit, the inlet end and the outlet end of the plurality of heat transfer tubes are A heat exchanger for a refrigerant condenser, characterized in that all are connected to a separate single header chamber to form the inlet side conduit and the outlet side conduit is composed of one heat transfer tube. 2. An intermediate-portion conduit through which a refrigerant flows midway between the inlet-side conduit and the outlet-side conduit, the intermediate-portion conduit comprising:
The heat exchanger for a refrigerant condenser according to claim 1, wherein all of the ends of the plurality of heat transfer tubes are connected to each single header chamber. 3. The heat transfer tube constituting the outlet side conduit is thicker than other heat transfer tubes.
The heat exchanger for a refrigerant condenser described. 4. The thickness of the heat transfer tube forming the outlet side pipe and the thickness of each heat transfer tube forming the intermediate pipe are made larger than the thickness of the other heat transfer tubes. The heat exchanger for a refrigerant condenser described. 5. A heat transfer tube forming at least an outlet side conduit has a plurality of refrigerant passages therein, and the equivalent diameter of the leeward side refrigerant passage is smaller than that of the windward side refrigerant passage. The heat exchanger for a refrigerant condenser according to claim 1, 2, 3, or 4. 6. An internal structure similar to the internal structure of the heat transfer pipe according to claim 5 is adopted not only for the outlet side pipe line but also for the heat transfer pipes forming other pipe lines. A heat exchanger for a refrigerant condenser according to any one of 1 to 5. 7. The heat exchanger for a refrigerant condenser according to claim 1, wherein the cross-sectional area of the refrigerant flow passage is made smaller in the order of the inlet side pipeline, the intermediate section pipeline and the outlet side pipeline.