JPH02272299A - Lamination type heat exchanger - Google Patents

Abstract

PURPOSE:To enhance a heat-exchanging efficiency by providing a channel at the bottom of the folded portion of a U-shaped refrigerant passage, the depth of the channel being deeper than the recessed part of each of heat transfer tube plates in a direction normal to an air stream, and the channel being formed in substantially parallel to the air stream. CONSTITUTION:Since a channel 22 is provided at the bottom of the folded portion of a U-shaped refrigerant passage 16 so as to be deeper than the recessed part 15 of each of heat transfer tube plates 11 and in substantially parallel to an air stream, more liquid refrigerant gathers in the channel 22 due to a centrifugal effect when the refrigerant takes a U-turn. The liquid refrigerant gathered in the channel 22 is made to flow toward the upstream side of the air stream along the channel 22 and flows directly into the flowing zone on the upstream side of the air stream in the U-shaped refrigerant passage 16, so that the liquid refrigerant is more supplied to the upstream side of the air stream where a thermal load is greater. As a result, an areal rate that is occupied by gas refrigerant, which does not contribute to heat exchange, on the flowing zone side on the upstream side of the air stream in the refrigerant passage 16 is decreased, and a heat-exchanging efficiency is improved. In addition, since a temperature on the tube wall of each of heat transfer tube plates 11 of a flat heat transfer tube 10 is high, the refrigerant flows more in the flowing zone on the upstream side of the air stream, where the viscosity of a freezer oil attached to the tube wall is low, whereby a flowing effect on the oil by the refrigerant is also improved. Accordingly, cooling performance is enhanced, the freezer oil is made easier to flow, and the return of the oil is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminated heat exchanger used in air conditioners and the like, and particularly to a laminated heat exchanger suitable for an evaporator for a car air conditioner.

[Conventional technology]

As a conventional stacked heat exchanger used as an evaporator, there is a technique described in Japanese Patent Application Laid-Open No. 63-21494.

FIG. 5 shows the prior art described in the above-mentioned publication, and is a front view of a heat exchanger tube plate viewed from a direction perpendicular to the air flow.

In the conventional technology shown in FIG. 5, two heat exchanger tube plates 1 and 2 are used.
are combined to form a set of flat heat exchanger tubes.

Each heat exchanger tube plate 1.2 has a U-shaped recess 5 formed in a joining rib 3 on the outer periphery and a partition wall 4 in the center. A refrigerant inlet 6 communicates with one end of the recess 5, and a refrigerant ratio lower communicates with the other end. Inside the recessed portion 5, a plurality of rows of ribs 8 are provided in the upstream and downstream regions of the air flow A, and a large number of ribs 8 are arranged in each row. The ribs 8 are arranged in an X-shape when the two heat exchanger tube plates 1 and 2 are combined, as shown by solid lines and broken lines in FIG. At the center of each heat exchanger tube plate 1, 2, the partition wall 4 is provided with notches 9a, 9b spaced apart from each other on the lower side.

Inside the flat heat exchanger tube constructed by combining the two heat exchanger tube plates 1 and 2, a U-shaped refrigerant passage is formed by combining two U-shaped recesses 5. One end of this U-shaped refrigerant passage communicates with a refrigerant inlet 6 provided on each heat exchanger tube plate 1, 2, and the other end communicates with a refrigerant volume lower provided on each heat exchanger tube plate 1, 2. are doing. Further, within the refrigerant passage, the ribs 8 provided on each heat exchanger tube plate 1.2 are combined in an X-shape, thereby forming the refrigerant passage in a zigzag shape.

A plurality of sets of the flat heat transfer tubes are stacked with heat transfer fins (not shown) in between, and the refrigerant inlets 6 provided on the heat transfer tube plates 1 and 2 of each set are connected to a refrigerant inlet vibrator (not shown) in series. The refrigerant volume lowers provided in each set of heat transfer tube plates 1 and 2 are connected in series to a refrigerant outlet vibrator (not shown) to transmit air and the refrigerant flowing in the U-shaped refrigerant passage. It constitutes a laminated heat exchanger that exchanges heat via heat fins.

[Problem to be solved by the invention]

In the conventional technology, the refrigerant stagnation S that tends to be formed along the partition wall 4 in the center in the region where the refrigerant flows from the bending part in the U-shaped refrigerant passage in each flat heat transfer tube toward the lower refrigerant amount side. On the other hand, a portion of the refrigerant flowing from the refrigerant inlet 6 toward the bent portion is introduced through the notches 9a and 9b provided in the partition wall 4 to eliminate the stagnation S of the refrigerant.

By the way, in this type of laminated heat exchanger, each heat exchanger tube plate 1,
Since the large number of ribs 8 provided on the pipes 2 intersect in an X-shape and the refrigerant passage is configured in a zigzag shape, the resistance of the pipes as a whole becomes almost uniform along the flow direction of the refrigerant.

For this reason, the front of the flat heat exchanger tube (direction perpendicular to the air flow)
The flow of refrigerant seen from above is a flow in which the proportion of gas refrigerant and liquid refrigerant is almost uniform.

However, the heat load of the gas-liquid two-phase refrigerant that has made a U-turn and flowed into the upstream side of the air flow A along the U-shaped refrigerant passage is large, and the evaporation of the liquid refrigerant is active. There is a problem that there is a shortage of refrigerant in the upstream basin, and most of the inside of the flat heat exchanger tube becomes a gas refrigerant region with poor heat transfer coefficient, resulting in a decrease in heat exchange efficiency.

The prior art does not consider this point.

The purpose of the present invention is to flow a large amount of liquid refrigerant into the upstream region of the air flow in the U-shaped refrigerant passage formed in each flat heat transfer tube, thereby improving heat exchange efficiency and making it easier for refrigerating machine oil to flow. The object of the present invention is to provide a laminated heat exchanger that can effectively return oil.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a heat exchanger tube plate at the bottom of a bent part of a U-shaped refrigerant passage that constitutes a set of two flat heat exchanger tubes in a direction perpendicular to the airflow than the recessed part of each heat exchanger tube plate. A groove is provided which is deep and allows liquid refrigerant to collect and flow approximately parallel to the air flow direction.

[Effect]

The refrigerant flowing toward the bend in the downstream region of the air flow in the U-shaped refrigerant passage formed in each flat heat transfer tube reverses its flow direction when it reaches the bend in the refrigerant passage, and the air in the refrigerant passage reaches the upstream basin. On the upstream side of the air flow in the refrigerant passage, the difference in the evaporation temperature of the refrigerant with the air to be cooled is larger than on the downstream side, so evaporation of the liquid refrigerant is promoted, and all of the refrigerant evaporates at the refrigerant outlet of each flat heat transfer tube. It vaporizes and becomes a gas refrigerant that flows out from each flat heat exchanger tube.

The heat load in the air flow direction in each flat heat exchanger tube carbonizes in proportion to the temperature difference between the air and the refrigerant, and reaches its maximum at the air inlet end where the temperature difference between the air and the refrigerant is the greatest. There is a sharp drop along the direction. Therefore, among the U-shaped refrigerant passages in each flat heat transfer tube, the evaporation effect of the refrigerant flowing in the region near the end on the air inflow side is significant.

Therefore, in the present invention, a groove is provided at the bottom of the bent part of the U-shaped refrigerant passage, deeper than the recessed part of each heat exchanger tube plate and almost parallel to the air flow, so that the centrifugal force when the refrigerant makes a U-turn is A lot of liquid refrigerant collects in the groove.

The liquid refrigerant that has gathered in the groove is blown along the groove toward the upstream side of the air flow, and directly flows into the upstream region of the air flow in the U-shaped refrigerant passage. A large amount of liquid refrigerant is supplied to the upstream side.

As a result, the area ratio occupied by the gas refrigerant that does not contribute to heat exchange on the upstream side of the air flow in the refrigerant passage is reduced, so the heat exchange efficiency is improved and the cooling capacity can be significantly improved.

In addition, since the tube wall temperature of each heat exchanger tube plate of the flat heat exchanger tube is high,
Since a large amount of refrigerant flows through the upstream region of the air flow where the viscosity of the refrigerating machine oil adhering to the pipe wall is low, the effect of the refrigerant on transporting oil is also significantly improved, and oil return can be improved.

【Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a front view of the heat exchanger tube plate constituting the flat heat exchanger tube of the laminated heat exchanger of the present invention, viewed from a direction perpendicular to the air flow;
FIG. 2 is a sectional view taken along line nn@ in FIG. 1, FIG. 3 is a perspective view showing an embodiment of the laminated heat exchanger of the present invention, and FIG. 4 is an explanatory view of the operation of the heat exchanger tube plate.

The flat heat exchanger tube 10 shown in FIGS. 1 and 2 is constructed by combining two heat exchanger tube plates 11 and 12.

As shown in FIGS. 1 and 2, each heat exchanger tube plate 11, 12 has a joining rib 13 formed on its outer periphery.

A partition wall 14 provided at the center of the interior and the joining rib 1
3 and the partition wall 14, a refrigerant inlet tank 17 and a refrigerant inlet 19 formed at one end of the U-shaped recess 15, and the other end of the recess 15. Refrigerant outlet tank 18 formed on the side
and a refrigerant outlet 20, a rib 21 provided in the recess 15, a groove 22 provided at the bottom of the bent portion of the U-shaped recess 15, and a folded portion 23 formed at the lowest part. It is configured as follows.

As can be seen from FIG. 2, the two heat exchanger tube plates 11 and 12 have a joining rib 13 on the outer periphery and a partition wall 14 in the center.
It is designed to be in close contact with each other.

U-shaped recesses 15 formed in each of the heat exchanger tube plates 11 and 12 are combined to form a U-shaped refrigerant passage 16.

The outer end of the U-shaped refrigerant passage 16 is connected to each heat exchanger tube plate 11.
Refrigerant inlet tank 17 and refrigerant inlet 1 formed in 12
9, and the other end communicates with a refrigerant outlet tank 18 and a refrigerant inlet 20 formed in each heat exchanger tube plate 11.12.

The ribs 21 are provided in two rows in the width direction in this embodiment and in large numbers in the vertical direction inside the U-shaped recess 15 of each heat exchanger tube plate 11.12. As shown, the ribs 21 on the heat exchanger tube plate 11 side and the ribs 21 on the heat exchanger tube plate 12 side are provided so as to be combined with each other in an X-shape. By combining the large number of ribs 21 in an X-shape, the refrigerant passage 16
is formed in a zigzag shape.

The groove portion 22 is formed in each heat exchanger tube plate 11.12.
As can be seen from FIG. 2, the bottom of the bent portion of the letter-shaped recess 15 is formed to be deeper in the direction perpendicular to the air flow A than the recess 15, and as shown in FIG.
It is formed long and almost parallel to air flow A.

As shown in FIG. 2, the folded portion 23
Bend the bottom part of heat exchanger tube 12 into an L shape.
It is formed by bending into a mold to maintain the spacing between the flat heat exchanger tubes 10.

The two heat exchanger tube plates 11 and 12 are assembled into a set of flat heat exchanger tubes 10 by joining the joining ribs 13 and the partitions N and 14 by welding or the like.

Then, as shown in FIG.
and end plates 25, 2 at both ends of the row of heat transfer fins 24.
6, connect the refrigerant inlet 19 provided in the heat exchanger tube plate 11. A stacked heat exchanger is constructed by connecting the refrigerant outlet 20 to the refrigerant outlet vibrator 28 in series.

In the laminated heat exchanger, the refrigerant flowing from the refrigerant inlet vibrator 27 flows through the refrigerant inlet 19. provided in the heat exchanger tube plate 11.12 of each flat heat exchanger tube 10. Through the refrigerant tank 17, U
The refrigerant is distributed almost uniformly within all the flat heat exchanger tubes 10 having the shape of the refrigerant passages 16.

The refrigerant flowing into the refrigerant passage 16 of each flat heat transfer tube 10 exchanges heat with the air to be cooled on the downstream side of the air flow A via the heat transfer fins 24, and as shown in FIG. While gradually increasing the proportion of the gas refrigerant G through evaporation, the liquid refrigerant and the gas refrigerant G become a two-phase gas-liquid flow in which the liquid refrigerant and the gas refrigerant G are almost uniformly mixed.
A flow path lea on the downstream side of the air flow A in the zigzag-shaped refrigerant passage 16 formed by combining the ribs 21 in an X-shape.
flows down in a zigzag pattern, reaches a bend 16c in the U-shaped refrigerant passage 16, and makes a U-turn. During this U-turn,
A centrifugal force acts on the refrigerant, and a high-density liquid refrigerant is blown to the outer periphery, and the U-shaped recess 15 of each heat exchanger tube plate 11.12 is formed at the bottom of the bent portion 16c of the U-shaped refrigerant passage 16.
Groove portion 22 formed deeper and approximately parallel to air flow A
A large amount of liquid refrigerant gathers in the area, and gas and liquid separate.

In the groove 22, the inertia of the liquid refrigerant with a higher density is greater than that of the gas refrigerant G even at the same flow rate. The wind blows upstream of the river. This blown liquid refrigerant flows directly into the flow path 16b on the upstream side of the air flow A in the refrigerant passage 16, so that a large amount of liquid refrigerant is supplied to the upstream side of the air flow A where the heat load is large.

As a result, the heat load distribution of the flat heat exchanger tube 10 along the air flow direction and the liquid refrigerant flow rate distribution within the flat heat exchanger tube 10 become appropriate. In other words, in the flow path 16b on the upstream side of the air flow A in the U-shaped refrigerant path 16, the boundary between the liquid refrigerant and the gas refrigerant G, which indicates the position where the liquid refrigerant evaporates, is as shown in FIG. In addition, since the area ratio occupied by the gas refrigerant G, which is almost parallel to the air flow A and does not contribute to heat exchange, is reduced, the heat exchange efficiency between the air and the refrigerant is improved, and the cooling capacity is greatly improved.

Furthermore, since the inflowing air temperature is high and the heat load is large on the most upstream side of the air, the temperature difference between the refrigerant evaporation temperature and the tube wall temperature of the flat heat exchanger tube 10 is maintained large. On the other hand, since the evaporation temperature of the flat heat exchanger tube 10 is constant, the tube wall temperature is high;
The viscosity of the refrigerating machine oil that adheres to the pipe wall is significantly reduced, making it easier to flow, and the refrigerant flow rate is large and the flow speed is faster. Together, these factors greatly improve the refrigerating machine oil draining effect. Oil returns well.

〔Effect of the invention〕

According to the present invention described above, a groove portion is provided at the bottom of the bent portion of the U-shaped refrigerant passage, the groove portion being deeper in the direction perpendicular to the air flow than the recessed portion of each heat exchanger tube plate and substantially parallel to the air flow. Because of this, a large amount of liquid refrigerant gathers in the groove due to the centrifugal force when the refrigerant makes a U-turn, and the liquid refrigerant that gathers in the groove is blown toward the upstream side of the air flow along the groove, and continues into the U-shaped refrigerant passage. Since the liquid refrigerant flows into the upstream region of the air flow in the refrigerant passage, a large amount of liquid refrigerant is supplied to the upstream side of the air flow with a large heat load, and as a result, it does not contribute to heat exchange in the upstream region of the air flow in the refrigerant passage. Since the area ratio occupied by the gas refrigerant is reduced, heat exchange efficiency is improved, which has the effect of significantly improving cooling capacity.

Further, according to the present invention, since the tube wall temperature of each heat exchanger tube sheet of the flat heat exchanger tube is high, a large amount of refrigerant flows in the upstream region of the air flow where the viscosity of the refrigerating machine oil adhering to the tube wall is low. Therefore, the effect of carrying out the oil by the refrigerant is greatly improved, which has the effect of improving oil return.

[Brief explanation of drawings]

FIG. 1 is a front view of the heat exchanger tube plate constituting the flat heat exchanger tube of the laminated heat exchanger of the present invention, viewed from a direction perpendicular to the air flow;
FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, FIG. 3 is a perspective view showing an embodiment of the layered heat exchanger of the present invention, FIG. FIG. 5 shows the prior art, and is a front view of a heat exchanger tube plate viewed from a direction perpendicular to the air flow.

Claims (1)

[Claims] 1. A combination of two heat transfer tube plates each having at least a U-shaped recess, a refrigerant inlet communicating with one end of the recess, and a refrigerant outlet communicating with the other end of the recess.
A plurality of sets of flat heat exchanger tubes are constructed, and a plurality of sets of the flat heat exchanger tubes are stacked with heat transfer fins in between, and each set of flat heat exchanger tubes is formed by combining the recessed portions of the two heat exchanger tube plates. In a laminated heat exchanger in which U-shaped refrigerant passages are connected in series through a refrigerant inlet and a refrigerant outlet provided in each heat exchanger tube plate, a base plate of each heat exchanger tube plate is placed at the bottom of the bent portion of the U-shaped refrigerant passage. A laminated heat exchanger characterized in that a groove portion is provided which is deeper in a direction perpendicular to the airflow than the recessed portion and collects and flows a liquid refrigerant substantially parallel to the airflow direction.