DE69729836T2 - Evaporator - Google Patents

Abstract

An evaporator (1) comprises at least one evaporator unit (1A) including a pair of headers (2,3) arranged one above the other in parallel and spaced apart by a distance, and parallel refrigerant tubes (4) having a width oriented in a front-rear direction and opposite ends joined to the respect headers (2,3). The refrigerant tubes (4) are each in the form of a flat tube (17) comprising flat left and right walls (11,12), front and rear walls (13,14) positioned between and joined to front and rear side edges of the left and right walls (11,12), and a plurality of reinforcing walls (15) positioned between and joined to the left and right walls (11,12), extending longitudinally thereof and arranged at a predetermined interval between the front and rear walls (13,14), the flat tube (17) having parallel refrigerant channels (16) inside thereof. The reinforcing walls (15) are formed with a plurality of communication holes (19) for causing the parallel refrigerant channels (16) to communicate with one another. The flat tube (17) is formed by a platelike left component (21) having a left wall forming portion (23) and a platelike right component (22) having a right wall forming portion (28). The front and rear walls (13,14) of the flat tube (17) comprise rightward projecting walls (24) projecting rightward from the respective front and rear side edges of the left component (21) integrally therewith and brazed to the right component (22) and leftward projecting walls (29) projecting leftward from the respective front and rear side edges of the right component (22) integrally therewith and brazed to the left component (20). The reinforcing walls (15) of the flat tube each comprise a reinforcing wall forming portion (25) projecting inward from the left wall forming portion (23) of the left component (21) and having an outer end brazed to the right wall (28) forming portion of the other component (22).

Description

BACKGROUND THE INVENTION

The The present invention relates to evaporators for use in air conditioning systems such as room air conditioners and air conditioning systems in motor vehicles.

One Evaporator of this type is disclosed, for example, in document US-A-5,323,851 shown. This document comprises an evaporator unit with a Pair of headers stacked on top of each other are arranged parallel and spaced apart, and parallel Coolant pipes, whose width is aligned in one direction from front to back is and their opposite Ends are connected to the respective headers, each one the coolant pipes has the shape of a flat tube, with flat left and right walls front and rear walls, between the front and back side edges of the left and right Walls arranged and a number of reinforcing walls connected between them the left and right walls are arranged and connected to these and extending in the longitudinal direction extend which reinforcing walls in one predetermined distance between the front and rear walls arranged are, with the flat tube parallel coolant channels in his Inner and is formed of a metal plate, and each the reinforcement walls one a reinforcement wall has forming area, the inward of the metal plate protrudes and one piece is formed with this.

Furthermore For example, document EP-A-0 617 250 discloses a coolant tube for use in heat exchangers, with a flat aluminum tube with parallel coolant channels in its interior and flat upper and lower walls and a number of reinforcing walls, the with through holes are provided, through which the parallel coolant channels communicate with each other stand. The flat aluminum tube is made up of two upper and lower Aluminum sheets formed by the opposite side edges of the lower sheet upwards be bent and the curved edges of the respective side edges the upper aluminum sheet to be connected to a hollow Area is formed. The reinforcement walls become formed by connecting the inner surface of the upper wall ribs, which project from the bottom wall inwards. The connection holes become formed by cutouts in the edges of the ribs in predetermined intervals are provided and their openings be completed by the top wall.

The terms "forward direction", "backward direction", or "front-to-rear direction" used herein refer to a direction parallel to the flow direction of the air through the evaporator, and the term "left-to-right direction" refers to one Direction perpendicular to the above direction. In the description with reference to 3 is referred to the left side of the drawing as "front", the right side as "back", on the lower side as "left" and on the upper side as "right".

Further, conventional evaporators for use in automotive air conditioning systems are film evaporators such as those disclosed in JP-A-230064/1991. The disclosed film evaporator comprises a plurality of pipe members each consisting of a pair of vertically elongated plates, which are produced by pressing and provided on their inside with projecting ribs extending in the vertical direction, which plates face each other and with the inside Ribs are secured together, and are soldered together at the side edge portions. The tubular members each have a flat tubular portion extending vertically and are juxtaposed with respect to the direction of their thickness into a sheet arrangement with a cooling fin disposed between each pair of adjacent members. The tubular members each have a bulging tank portion attached to each of its upper and lower ends and communicating with the flat tubular portion, and are connected to each other at their tank portions by brazing so as to communicate with each other at the tank portions. According to 18 that the pipe element 70 shows the ribs point 73 . 74 the vertically extended plates 71 . 72 inwardly, so that they have a roughly U-shaped cross-section. Ribs 73 the plate 71 are between the ribs 74 the other plate 72 arranged, and their projecting ends are to the other plate 72 soldered, and the ribs 74 the other plate 72 are at the projecting ends of the plate 71 soldered, creating a variety of parallel coolant channels 75 is formed.

However, the conventional evaporator has the following problem. Ribs 73 . 74 the plates 71 . 72 have a U-shaped cross-section, so that unused space areas that do not arise contribute to the passage of the coolant, which with 76 in 18 are designated, and which at a predetermined width of the tubular element, a limitation of increasing the number of coolant channels 75 cause. Moreover, the stretching of the material in the manufacturing process is limited by the constraints associated with the pressing techniques, so that when the space between the adjacent ribs 73 . 74 is reduced, cracks in the plates 71 . 72 occur. The space between the adjacent ribs 73 . 74 must therefore be kept relatively large, so that it is impossible, the coolant channels 75 to give a corresponding diameter and an increased number of channels 75 provide, if the pipe element 70 has a predetermined width. Thus, there is a limit on the heat exchange performance, that is, the improvement of the evaporation efficiency of the coolant.

It Seems that the above problem is overcome by an evaporator can be, which comprises at least one evaporator unit, the one A pair of manifolds that are parallel to each other and from each other spaced apart, and parallel coolant tubes, the opposite Ends are connected to the respective headers, each one the coolant pipes has the shape of a hollow extruded part, with flat left and right walls and a number of reinforcing walls, the arranged between the left and right walls and with these are connected, in the longitudinal direction extend and are arranged at a predetermined distance. at this evaporator it is possible A larger number of coolant channels and the channels a smaller equivalent diameter in contrast to the flat tubular portion of the tubular element of the conventional Evaporator. To achieve an improvement in heat exchange efficiency, this means, the efficiency of the coolant evaporation, and to create a compact evaporator, it is desirable that the coolant pipe a reduced wall thickness and a reduced width in the left-right direction having. However, extruded materials have limitations associated with the extrusion techniques, to limitations the reduction in wall thickness, while the dimensional accuracy of the pipe is ensured, as well as in the reduction of the lateral Width of the pipe under consideration the dimensional accuracy. For extrudates it is beyond that impossible, connecting holes in the reinforcement walls to Connecting the parallel coolant channels with each other to provide, though these holes considered effective for achieving increased efficiency become.

SUMMARY THE INVENTION

It is an object of the present invention, all the above problems to overcome and to create a compact evaporator that faces the usual Evaporator in terms of heat exchange performance is improved, that is, in terms of the refrigerant evaporation efficiency, and further to the Evaporator comprising extruded hollow parts in terms of heat exchange efficiency, this means, the refrigerant evaporation efficiency is improved.

The The present invention provides an evaporator characterized by the features of claim 1 is characterized.

Of the inventive evaporator has coolant tubes each of which is in the form of a flat tube with flat left and right walls has front and rear walls between the front and rear ends of the left and right walls and arranged with these are connected, and a number of reinforcing walls between the left and right walls are arranged and connected to these and in the longitudinal direction extend and at a predetermined distance between the front and rear walls are arranged. The flat tube has in its interior parallel coolant channels and is made of a metal plate. Each of the reinforcement walls comprises a reinforcing wall forming portion projecting from the metal plate inside and in one piece is formed with this. In contrast to the flat tubular area the tubular element of the conventional evaporator, which is disclosed in JP-A-230064/1991, accordingly, the Number of coolant channels in the enlarged flat tube, while the corresponding diameter of the channels is reduced. Consequently is the heat exchange performance of the evaporator, that is, the efficiency of evaporation of the coolant over the Evaporator from the publication improved. About that In addition, the wall thickness of the coolant tube with a dimensional accuracy against an extruded hollow Be reduced component, the width in the left-right direction with the dimensional accuracy decreases. Therefore, the heat exchange performance, this means, the efficiency of evaporating the refrigerant of the present Evaporator, can be improved, and this can be compared to an evaporator, which consists of the hollow extrudate, more compact be designed.

Preferably, the reinforcement walls of the present evaporator having a number of Ver provided connection holes through which the parallel coolant channels communicate with each other. The connection holes are preferably offset when viewed from the left. Preferably, each of the reinforcement walls has an aperture ratio of 10 to 40%, which represents the ratio of all the connection holes in the reinforcement wall to the reinforcement wall.

The The present invention will now be described more specifically with reference to the accompanying drawings described.

SUMMARY THE DRAWINGS

1 Fig. 13 is a perspective view of the overall construction of a first embodiment of a vaporiser according to the prior art;

2 Fig. 12 is a graph showing the refrigerant flow through the first embodiment;

3 Fig. 12 is a partially broken perspective partial view showing a coolant pipe which is part of the first embodiment;

4 is an enlarged partial section through the coolant tube;

5 is a section along the line VV in 4 ;

6 Fig. 12 is a perspective view of the overall construction of a second embodiment of a vaporiser according to the prior art;

7 Fig. 12 is a graph showing the refrigerant flow through the second embodiment;

8th Fig. 15 is a perspective view showing the overall construction of a third embodiment of a vaporiser according to the prior art;

9 Fig. 10 is a diagram showing the refrigerant flow through the third embodiment;

10 Fig. 10 is a perspective view of the overall construction of a fourth embodiment of a vaporiser according to the prior art;

11 Fig. 12 is a graph showing the refrigerant flow through the fourth embodiment;

12 Fig. 15 is a perspective view showing the overall construction of a fifth embodiment of a prior art evaporator;

13 Fig. 12 is a graph showing the refrigerant flow through the fifth embodiment;

14 Fig. 15 is a perspective view of the overall construction of a sixth embodiment of a vaporiser according to the prior art;

15 Fig. 12 is a graph showing the refrigerant flow through the sixth embodiment;

16 Fig. 13 is a partially broken perspective view showing the overall construction of an embodiment of the evaporator of the present invention; and

17 Fig. 15 is a graph showing the results obtained in Example 2 and Comparative Example 3.

18 is a partial section through a tubular element of the conventional evaporator.

DESCRIPTION THE PREFERRED EMBODIMENTS

1 shows the overall construction of an evaporator as a first embodiment according to the prior art, 2 shows the coolant flow through the evaporator, and the 3 to 5 are partial views showing main components of the evaporator.

It is noted that the following embodiments of the evaporator represent the prior art and will be described by way of illustration only. In particular, the show 1 to 15 six known embodiments of the evaporator.

In In the following description, the term "aluminum" includes pure aluminum and other aluminum alloys.

According to 1 includes the evaporator 1 two evaporator units 1A each containing a pair of headers 2 . 3 comprise, parallel to each other and spaced from each other, parallel, flat coolant tubes 4 with a width oriented in the front-to-rear direction and the opposite ends with the respective headers 2 . 3 connected, and a corrugated aluminum cooling fin 5 located in the air passage space between each pair of coolant tubes 4 is arranged and attached to the two pipes 4 is soldered. The two evaporator units 1A are arranged parallel in the front-to-rear direction and spaced from each other. The upper manifolds 2 the two evaporator units 1A and their lower manifolds 3 are each connected by connecting lines 6 . 7 connected. The connection lines 6 . 7 are at their opposite ends respectively with the lengthwise middle portions of the two upper headers 2 and the lengthwise middle portions of the two lower header pipes 3 connected. A coolant inlet pipe 8th is with the bottom of the lengthwise middle portion of the lower connecting pipe 7 connected. A coolant outlet pipe 9 is with the upper side of the lengthwise middle portion of the lower connecting pipe 6 connected. According to 2 the coolant flows into the lower connecting pipe 7 through the inlet pipe 8th flows in a liquid phase, divided into the lower manifolds 3 the two evaporator units 1A , enters the vapor phase while passing through the coolant tubes 4 flows upwards, enters the upper header pipes 2 and then flows out of the outlet 9 through the upper connecting line 6 out.

As in the 3 to 5 is shown has each coolant tube 4 the shape of a flat tube 17 made of aluminum, the flat left and right walls 11 . 12 includes, as well as front and rear walls 13 . 14 placed between the front and rear side edges of the left and right walls 11 . 12 are arranged and connected to them, and a number of reinforcing walls 15 between the left and right walls 11 . 12 are arranged and connected to extend in the longitudinal direction and at a predetermined distance between the front and rear walls 13 . 14 are arranged. The pipe 4 has in its interior parallel coolant channels 16 on.

Between each pair of adjacent reinforcement walls 15 is the left wall 11 of the flat tube 17 on its inner surface with a number of protrusions 18 provided by the left wall 11 projecting to the right and are formed integrally with this and in the longitudinal direction of the wall 11 are arranged spaced so that an enlarged area is provided for heat exchange. The reinforcement walls 15 are with a number of connection holes 19 provided by which the parallel coolant channels 16 communicate with each other. The connection holes 19 are staggered when viewed from the left. If the holes 19 are provided, the fluid flowing through the parallel fluid channels 16 flows, even through the holes 19 in the transverse direction of the flat tube 17 and spreads over all fluid channels 16 so that it is mixed and any temperature difference in the fluid between the channels 16 is eliminated. As a result, an improvement in the heat exchange efficiency, that is, the efficiency of the evaporator of the coolant is achieved. Each of the reinforcement walls 15 has an opening ratio of 10 to 40%, preferably 10 to 30%, more preferably about 20%, which is the ratio of all communication holes 19 in the reinforcement wall 15 represents the reinforcement wall. The provided connection holes 19 then lead to a significant improvement in the heat exchange efficiency.

The flat aluminum tube 17 is through a left component 21 formed in the form of an aluminum plate, which is the left wall 11 , front and back walls 13 . 14 and reinforcement walls 15 forms, as well as by a right component 22 in the form of an aluminum plate, which is the right wall 12 and front and back walls 13 . 14 forms. The left component 21 includes a left wall forming area 23 , walls projecting to the right 24 , respectively from the front and rear side edges of the area 23 projecting to the right and are integrally formed with this and a reinforcing wall forming areas 25 coming from the left wall-forming area 23 inwardly projecting and integrally formed with this. A number of clippings 26 is in the right edges of the reinforcing wall forming areas 25 formed, and these are at a distance in the longitudinal direction of the areas 25 spaced, the outer ends of the wall-forming areas 25 are on the right wall 12 soldered, and the openings of the cutouts 26 are through the right wall 12 enclosed, creating communication holes 19 be formed. The left component 21 is outside on each of its front and rear side edges with a bevel 27 provided, which is inclined outwards to the right in the direction from front to back.

The right component 22 includes a right wall-forming area 28 and left projecting walls 29 , each to the left of the front and back side edges of the area 28 projecting and formed in one piece with this. The left projecting walls 29 have an initial height that is slightly greater than the sum of the height of the reinforcing wall forming areas 25 the left component 21 and the thickness of the left wall-forming area 23 (see the broken line in 4 ). The front and back walls 13 . 14 of the flat tube 17 be through the walls projecting to the right 24 the left component 21 and the walls projecting to the left 29 the right component 22 educated.

The left component 21 is formed of an aluminum solder sheet having only on its outer side a Lötmaterialschicht. The right component 22 is formed of an aluminum solder sheet having a solder layer on each of its opposite sides.

The left component 21 and the right component 22 are adapted to each other so that the walls projecting to the left 29 the right component 22 outside the respective right-projecting walls 24 the left component 21 are arranged and these overlap. The left end of each left-projecting wall 29 is bent inward from front to back and the inward curved portion 29A includes the chamfer 27 in touch contact, leaving the two components 21 . 22 be stapled together. In this state, every wall projecting to the right becomes 24 and the corresponding left-projecting wall 29 soldered together, the outer ends of the reinforcing wall forming areas 25 be with the right wall-forming areas 28 soldered, and every inward curved area 29a will be at the appropriate bevel 27 soldered, leaving the flat tube 17 is formed.

The left component 21 is formed by rolling. The right component 22 is formed by roll forming. The left component 21 is rolled by a known rolling mill. Optionally, the left component 21 be formed by a rolling mill comprising a central work roll and a number of planetary work rolls arranged around the central work roll, circumferentially equidistantly spaced and rotatable at the same peripheral speed as the central work roll. The central work roll or planetary work rolls are provided with annular grooves for forming the rightward projecting wall and annular grooves for forming the reinforcing wall on its peripheral surface along its entire circumference. The rib area between each pair of adjacent reinforcing wall forming grooves is provided with cavities for forming protrusions circumferentially spaced from the roller, and the bottom face defining each groove for forming the reinforcing wall has protrusions for forming cutouts. The aluminum soldering plate for the left component 21 is performed continuously between the central work roll and all planetary work rolls, whereby the arrangements of the grooves, cavities and cutouts are transferred to the sheet and the left component 21 the desired shape is awarded. According to 6 differs the evaporator 30 from the evaporator 1 according to the first embodiment in that a coolant inlet pipe 31 with the top of the lengthwise middle portion of the upper connection line 6 is connected while a coolant outlet conduit 32 with the bottom of the lengthwise middle portion of the lower connection line 7 connected is. Except for this feature, the second embodiment has the same construction as the first one.

As in 7 As can be seen, the coolant flowing through the inlet conduit 31 in the upper connecting line 6 enters, in a liquid phase divided into the upper manifolds 2 the two evaporator units 1A , then goes into the vapor phase while passing through the coolant tubes 4 flows downwards, enters the lower manifolds 3 and flows out of the outlet pipe 32 over the lower connecting pipe 7 out.

8th and 9 show another evaporator 35 ,

According to 8th includes the evaporator 35 two evaporator units 1A whose upper manifolds 2 at their right ends through a connecting line 36 are connected, through which the right ends of the manifolds communicate with each other. The lower manifolds 3 of the two units 1A are not connected. A coolant inlet line 37 is with the left end of the lower manifold 3 the rear evaporator unit 1A connected, and a coolant outlet line 38 is with the lin ken end of the lower manifold 3 the front unit 1A connected. The third embodiment is the same as the first embodiment except for this feature.

As in 9 is shown, the coolant flowing into the lower manifold 3 the rear unit 1A through the inlet pipe 37 flows in a liquid phase, through the coolant tubes 4 the unit up into the upper manifold 2 , then flows into the upper manifold 2 the front unit 1A through the connection line 36 , then flows through the coolant tubes 4 down into the lower manifold 3 and flows in the gas phase from the outlet conduit 38 out.

10 and 11 show another evaporator 40 ,

According to 10 includes the evaporator 40 two evaporator units 1A with upper and lower headers 2 . 3 , The upper manifolds 2 and the lower manifolds 3 are each at their left ends by connecting lines 41 . 42 connected. A coolant inlet line 43 is with the left side of the lengthwise middle portion of the lower connection line 42 connected while a coolant outlet line 44 with the left side of the lengthwise middle portion of the upper connection line 41 connected is. The fourth embodiment is the same as the first embodiment except for this feature.

As in 11 is shown, the coolant flowing through the inlet conduit 43 in the lower connection line 42 flows in a liquid phase, in the lower manifolds 3 of the two units 1A , then changes to a gas phase while passing up through the coolant tubes 4 of the two units 1A flows, then into the upper header pipes 2 to flow, and then flows over the upper connecting line 41 from the outlet pipe 44 out.

12 and 13 show another evaporator 45 ,

According to 12 includes the evaporator 45 two evaporator units 1A whose upper manifolds 2 together through a connecting line 6 are connected, which connects the lengthwise middle portions of these headers, while the lower manifolds 3 are not connected. A coolant inlet line 46 is with the lower side of the lengthwise middle portion of the lower manifold of the rear unit 1A connected, and a coolant outlet line 47 is at the lower side of the lengthwise middle portion of the lower header 3 the front unit 1A connected. Except for this feature, the fifth embodiment is the same as the first one.

Further flows according to 13 the coolant, which in a liquid phase in the lower manifold 3 the rear unit 1A through the inlet pipe 46 flows through, through the coolant pipes 4 up into the upper manifold 2 , then flows through the connecting line 6 in the upper manifold 2 the front unit 1A , then flows through the pipes 4 down into the lower manifold 3 and flows as a vapor phase from the outlet conduit 47 out.

14 and 15 show another evaporator 50 ,

According to 14 includes the evaporator 50 two evaporator units 1A whose upper manifolds 2 through a connecting line 6 are connected, which connects the lengthwise middle portions of the headers, while the lower manifolds are not in communication. A coolant inlet line 51 is with the left end of the lower manifold 3 the rear unit 1A connected, and a coolant outlet line 52 is with the left end of the lower manifold 1A connected. Except for this feature, the sixth embodiment is the same as the first embodiment.

As in 15 can be seen, the coolant flows in a liquid phase in the lower manifold 3 the rear unit 1A through the inlet pipe 51 flows in, up through the coolant tubes 4 in the upper manifold 2 , then flows through the connecting line 6 in the upper manifold 2 the front unit 1A , then flows through the coolant pipes 4 down into the lower manifold 3 and flows as a vapor phase from the outlet conduit 52 out.

16 shows an evaporator 55 which is an embodiment of the invention.

According to 16 includes the evaporator 55 a single evaporator unit 55A , The unit 55A includes a pair of headers 56 . 57 arranged one above the other in parallel and spaced from each other and a number of coolant tube groups 58 , each having a number of, for example, three coolant tubes 4 which are arranged at a distance in the front-to-rear direction and have a width oriented in this direction and their opposite ends to the respective headers 56 . 57 are connected. The pipe groups 58 are arranged side by side at intervals in the direction from left to right.

The upper manifold 56 includes a box-like manifold body 59 which is open at the bottom, and a manifold plate 60 that closes the lower opening. The coolant pipes 4 are at their upper ends to the manifold plate 60 connected.

The lower manifold 57 corresponds to an inverted upper manifold 56 and has a manifold plate 60 on, to which the lower ends of the pipes 4 are connected. The lower manifold 57 is at a central area with respect to its length with a division 61 provided the interior of the lower manifold 57 in two parts. A coolant inlet line 62 is on the right side of the division 61 with the bottom wall of the lower manifold 57 connected, and a coolant outlet line 63 is connected to the bottom wall on the left side of the division.

In this evaporator 55 the coolant flows through the inlet pipe 62 in a liquid phase on the right side of the division 61 in the unit 55A flows in, through all pipes 4 right from the division 61 up, then flows through the upper manifold 56 , flows further into all pipes 4 to the left of the division 61 , flows in these tubes down into the lower manifold 57 to the left of the division 61 and flows through the outlet conduit in a vapor phase 63 out.

EXAMPLES AND COMPARATIVE EXAMPLES

example 1

In this example, the evaporator 55 used.

The evaporator 55 had a length L in the left-to-right direction of 227 mm, in the front-to-back direction, a width W of 60 mm, and a height H of 235 mm. The flat tube 17 , each as a coolant tube 4 was used had a width of 18 mm in the front-to-back direction and a thickness of 1.7 mm in the left-to-right direction. The number of pipe groups 58 , each three coolant tubes 4 included 22.

First, the air side heat transfer area A (m ² ) and the coolant side heat transfer area B (m ² ) were determined. Using HFC134a as the refrigerant, the heat exchange amount, Q (kcal / h) and the air side resistance to the air passage ΔPa (wet) (mm Aq) were measured under the following conditions: air inlet temperature (dry bulb: 25 ° C, wet bulb: 17.8 ° C), pressure before the expansion valve: 16.5 kg / cm ² G, subcooling: 5 °, evaporator outlet pressure: 1.8 kg / cm ² G, superheating: 5 ° and air inlet throughput: 450 m ³ / h.

Comparative Example 1

It an evaporator was used, the coolant tubes made of hollow aluminum extrudate instead of the flat coolant tubes included in the above example. The Size of the evaporator was the same as in the previous example, and the coolant tubes Hollow extrudate was the same size as the flat tubes of this example.

First, the air side heat transfer area A (m ² ) and the coolant side heat transfer area B (m ² ) were determined. Using HFC134a as the refrigerant, the heat exchange amount Q (kcal / h) and the air side resistance to the air flow ΔPa (wet) (mm Aq) were measured under the same conditions as in the above example.

Comparative Example 2

In This comparative example used the same evaporator as in the previous example, except that the evaporator having the construction disclosed in JP-A-230064/1991, and a width in the front-to-back direction of 75 mm.

First, the air side heat transfer area A (m ² ) and the coolant side heat transfer area B (m ² ) were determined. Using HFC134a as the refrigerant, the heat exchange amount Q (kcal / h) and the air side resistance to the air flow ΔPa (wet) (mm Aq) were measured under the same conditions as in the previous example.

In summary the results are shown in the following table.

The in the table given values for the heat transfer surfaces A and B, the heat exchange amount Q and the resistance ΔPa (moist) are each in proportion to the corresponding one Value of Comparative Example 2, which is set as 100 becomes.

The Table shows that the evaporator of Example 1 with respect to the heat exchange corresponds to the evaporator of Comparative Example 2, but one has smaller width and is smaller overall, probably there the former has an increased heat transfer area the coolant side but has a smaller width in the front-to-front direction rear than the latter. Furthermore, the evaporator shows Example 1 a smaller airside resistance to the air passage on than that of Comparative Example 2, so that a larger amount of air is passed, resulting in a larger heat exchange quantity. Of the Evaporator of Comparative Example 1 has a smaller heat transfer amount as that of Example 1, although it has the same size like the evaporator of Example 1. This seems to be the smaller coolant side Heat exchange surface of for comparison used evaporator and the lack of connection holes in attributed to the reinforcement walls to be the parallel channels connect with each other.

Example 2

The coolant tube 4 Example 1 was used to determine the relationship between the average quality of the refrigerant (the mass fraction of the vapor in the refrigerant) X (%) and the heat transfer coefficient h by the following method. The coolant tube was placed in a cooling water channel, and HFC134a as a refrigerant was passed through the tube while allowing cooling water to flow through the channel. After a certain period of time, the heat transfer coefficient h at different average quality values of the refrigerant was measured under the following conditions: refrigerant flow rate: 400 kg / m ² · s; Heat flow between coolant and cooling water, 8 kW / m ² ; Coolant saturation temperature T, 40 ° C; and cooling water flow rate at a Reynolds number of 1500.

Comparative Example 3

The Coolant pipe from Comparative Example 1 was used to illustrate the relationship between the average quality of the coolant HFC134a, X (%) and the heat transfer coefficient h to be determined by the same method as in Example 2.

17 shows the results of Example 2 and Comparative Example 3.

17 Fig. 2 shows that in Example 2, an enlarged heat transfer surface area and communication holes in the reinforcing walls are larger in heat transfer coefficient h than Comparative Example 3, in which the coolant side heat transfer area is small and no communication holes are present.

Claims (5)

Evaporator ( 55 ), with a single evaporator unit ( 55A ) with a pair of headers ( 56 . 57 ), which are arranged one above the other in parallel and spaced from each other, and parallel coolant raw ren ( 4 ) whose width is oriented in the direction from front to rear and whose opposite ends with the respective headers ( 56 . 57 ), each of the coolant tubes ( 4 ) the shape of a flat tube ( 17 ), with flat left and right walls ( 11 . 12 ), front and rear walls ( 13 . 14 ) located between the front and rear side edges of the left and right walls ( 11 . 12 ) are arranged and connected to these, and a number of reinforcing walls ( 15 ) between the left and right walls ( 11 . 12 ) are arranged and connected to these and extend in the longitudinal direction, which reinforcing walls ( 15 ) at a predetermined distance between the front and rear walls ( 13 . 14 ) are arranged, wherein the flat tube ( 17 ) parallel coolant channels ( 16 ) in its interior and consists of two metal plates ( 21 . 22 ) is formed, and each of the reinforcement walls ( 15 ) an area forming a reinforcing wall ( 25 ), which faces inward from one ( 21 ) protrudes from the metal plates and is formed integrally therewith, characterized in that the evaporator unit ( 55A ) a number of coolant tube groups ( 58 ), each of which comprises a number of coolant tubes ( 4 ), which are arranged at a distance in the front-to-rear direction, which coolant tube groups ( 58 ) are arranged side by side in a direction from left to right. An evaporator according to claim 1, wherein the flat tube ( 17 ) by a plate-like left component ( 21 ) with a left wall-forming area ( 23 ) and a plate-like right-hand component ( 22 ) with a right wall-forming area ( 28 ) is formed, and each of the front and rear walls ( 13 . 14 ) of the flat tube ( 17 ) either a right-projecting wall ( 24 ) extending to the right of each of the front and rear side edges of the left-hand component (FIG. 21 ) projecting and integrally formed therewith and is soldered to the right-hand component, or a left-projecting wall ( 29 ) to the left of each of the front and rear side edges of the right-hand component ( 22 ) protrudes and is formed integrally therewith and to the left component ( 21 ), wherein the reinforcement walls ( 15 ) of the flat tube ( 17 ) an area forming a reinforcing wall ( 25 ) extending inwardly either from the left wall-forming area (FIG. 23 ) of the left component ( 21 ) or the right wall-forming area ( 28 ) of the right component ( 22 ), integrally formed therewith and having an outer end soldered to the other wall-forming portion. An evaporator according to claim 2, wherein the reinforcing walls ( 15 ) with a number of connection holes ( 19 ), through which the parallel coolant channels ( 16 ) communicate with each other. An evaporator according to claim 3, wherein the communication holes ( 19 ) are arranged offset from the left. An evaporator according to claim 3 or 4, wherein each of the reinforcement walls ( 15 ) has an aperture ratio of 10 to 40%, which is the ratio of all communication holes ( 19 ) in the reinforcement wall to the reinforcement wall ( 15 ).