US20080110604A1

US20080110604A1 - Heat exchanger

Info

Publication number: US20080110604A1
Application number: US11/937,698
Authority: US
Inventors: Rolf Konrad Janssen
Original assignee: Individual
Current assignee: Visteon Global Technologies Inc
Priority date: 2006-11-10
Filing date: 2007-11-09
Publication date: 2008-05-15
Also published as: DE102006055837A1; JP2008122070A

Abstract

A heat exchanger for use in a vehicle air conditioning system is provided. The heat exchanger includes a plurality of heat exchanger registers adapted to transfer heat from an air flow passing thereby to a refrigerant flowing therethrough. The heat exchanger further includes a plurality of junction elements in fluid communication with the heat exchanger registers. Each of the junction elements is disposed between one of a pair of top collector lines and a pair of bottom connector lines of the heat exchanger registers. The junction elements have a hydraulic flow area that militates against pressure losses over the heat exchanger. A heat exchanger having an arrangement of three heat exchanger registers and a vehicle air conditioning system including the heat exchanger are also provided.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of German Patent Application No. 102006055837.5-16 HEAT EXCHANGER, PARTICULARLY AS EVAPORATOR OF VEHICLE AIR CONDITIONING UNITS filed on Nov. 10, 2006, hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to an arrangement for optimized flow through heat exchangers, and more particularly an evaporator in an air conditioning system of a vehicle.

BACKGROUND OF THE INVENTION

In the evaporator of an air conditioning unit, the refrigerant absorbing heat from the air flow thereby evaporates. The air flow is cooled by extracting heat from it. Different types of heat exchangers used as evaporators in vehicle air conditioning units are known.
Two-row heat exchangers are typically used as evaporators in vehicle air conditioning units. In order to extend the flow path and hence the temperature spread of the refrigerant over the heat exchanger, according to EP 1 058 070 A2, the collector lines are divided using partition walls. This creates a two-row heat exchanger composed of four heat exchanger registers passed one after the other. In this way, the temperature spread is improved and therefore, a higher transfer capacity can be obtained.
However, the temperature distribution over the outlet cross-sectional area is inhomogeneous. In addition, the pressure loss over the heat exchanger is increased due to frequent changes in direction of flow. Further, it is disadvantageous that inserting partition walls requires relatively high technological effort, the positions of the partition walls having to be determined anew, whenever dimensions are changed.
Similar versions of directing the flow are found in DE 103 12 780 A1 for disk and flat tube evaporators; and in EP 0 769 665 B1, EP 0 862 035 B1, and U.S. Pat. No. 6,047,769 A for disk evaporators.
In WO 2005/100900 A1, throttling stages are inserted into the collector lines to achieve homogeneous flow through the individual evaporator tubes within the register. In this way, registers can be homogeneously passed, even if the ports are disposed on the same side. However, insertion of throttling stages involves high effort, causes additional pressure losses, and above all, has to be dimensioned and manufactured individually for each size. This makes these heat exchangers very expensive.
Two-row evaporators are disadvantageous in that the temperature distribution of the outflowing air is inhomogeneous over the cross-sectional area of the heat exchanger. Furthermore, it is desirable that as little vehicle space as possible be needed for the heat exchanger. Thus, design should aim at high heat exchanging capacities requiring little space. This can be realized through a large heat exchanger surface and/or an advantageous arrangement and flow through the evaporator tubes such as in counter-current or cross-current heat exchangers. Especially good heat transfer from the heat carrier, or the refrigerant, respectively, is to be aimed at. For that reason, series connection of the single heat exchanger registers is advantageous, in order to realize a temperature difference as high as possible between the heat carrier medium and the air over the total heat exchanger surface.
A well dimensioned, three-row heat exchanger has advantages. However, in three-row heat exchangers the port lines typically are on different sides, which requires higher tubing effort and makes manufacturing more difficult.
In DE 102 20 533 A1, FIGS. 6 and 7, a three-row heat exchanger is described where the ports are on the same side. However, the register, which is not homogeneously passed due to the ports being disposed on the same side, is arranged last before the outlet of the air from the heat exchanger. Therefore, no homogeneous temperature distribution over the air outflow cross-sectional area can be realized.
All known heat exchangers have the disadvantage that either the evaporator tubes are arranged in two rows or, for three-row evaporator tubes, the ports of the collector lines, to which the evaporator tubes are connected, are disposed on different sides so that tubing of the collector lines is expensive. Additionally, the flow through the evaporator tubes is not optimal, or for improved distribution of the refrigerant, additional inserts such as separating disks or throttling stages are needed in the collector lines.
The problem is that each advantage gives rise to a disadvantageous change of one or several other parameters.
Therefore, the invention aims at establishing a heat exchanger in such a way that homogeneous temperature distribution over the air outlet cross-section can be achieved. Furthermore, both ports of the heat exchanger are to be on the same side without complicated tubing or inserts in the collector lines made necessary.

SUMMARY OF THE INVENTION

The problem is solved according to the invention by that the first and the last heat exchanger register, in direction of the air flow, are provided with ports arranged diagonal and the ports of the middle heat exchanger register are on the same side. Therefore the heat exchanger ports are arranged on one side and the junctions between the first and the middle as well as between the middle and the second heat exchanger register are arranged opposite to each other, thus established at a short distance to each other. Especially due to the diagonally connected last heat exchanger register, because of equal pressure losses over all flat tubes of the register, highly homogeneous refrigerant distribution and, thus, uniform surface temperature of the heat exchanger register, are achieved. This circuitry is also known as a Tichelmann system. Subsequently, this arrangement leads to the desired highly homogeneous distribution of the air temperature over the outlet cross-sectional area.
Furthermore, design of the collector lines is simplified. It is not required to determine partitions and/or throttles of the evaporators. Also, high internal pressures in the refrigerant circuit, particularly for systems using carbon dioxide as refrigerant (R744-systems), can be more easily controlled because of simpler structures of the collector lines.
The porting lines of the heat exchanger are arranged on the same side. This eliminates expensive additional tubing.
The hydraulic flow area of the junction elements being at least 60% of the flow area of the collector lines ensures low pressure losses over the heat exchanger.
Advantageous embodiments of the heat exchanger, particularly as an evaporator in vehicle air conditioning units, follow from the subclaims.
An advantageous embodiment of the invention indicates the optimal flow area of the junction elements. On the one hand, the pressure losses are kept small, and on the other hand, easy manufacture and assembly of the junction elements are achieved. Also the space requirement of the heat exchanger caused by the junction elements is reduced. The optimum flow area of the junction elements is 75-110% of the flow area of the collector lines.
According to an embodiment of the invention, the junction elements are designed as 180° tube bends. The 180° tube bends are a simple type of junction that can be established readily and cost effectively using standard components.
According to another advantageous embodiment, the junction elements are established as junction tube sockets. This embodiment discloses a type of junction of the collector lines that saves considerable space and cost. The junction tube sockets are accordingly adapted with their faces to the pierced circumferential surfaces of the collector lines and mounted, for example, by brazing.
According to another advantageous embodiment of the invention, the heat exchanging area is established as multiple-channel flat tube evaporator tubes connected to the collector lines. Flat tube evaporators, particularly multiple-channel flat tube evaporators, enable flexible sizes and versions to be cost effectively established. Multiple-channel flat tube evaporators can be cost effectively manufactured with little machining effort as extruded profile. They are particularly suitable for use at high operational pressures presenting good specific heat exchange capacities at the same time.
In an embodiment of the invention, a port extension line is arranged such that a heat exchanger port is extended into the port area of the other heat exchanger port, in each case. This makes possible that both ports are arranged neighboring each other. By means of one or rather two port extension lines, both heat exchanger ports can be arranged so that advantageous insertion of the heat exchanger into the vehicle and easier assembly of the heat exchanger are achieved. Also, both heat exchanger ports can be combined to a common heat exchanger porting piece.
As an embodiment of the invention, the top and the bottom collector lines each are combined to respective collector blocks. The corresponding passages of the collector lines and the port sockets for connecting the evaporator tubes are disposed in a collector block. This simplifies manufacture of the heat exchanger as the number of components is reduced. The collector block can be manufactured from, for example, extruded material available as yard goods, and easily and cost efficiently manufactured. The collector blocks are also suited for modular manufacture that can be configured to have different sizes, capacities and porting versions, and are easy to assemble.
In one embodiment, the passages of the collector lines are connected by junction holes according to the desired path of the refrigerant. The junction holes can easily be made in the collector block by drilling. The junction holes and passages of the collector lines can be closed with plugs as needed.
Another advantageous embodiment of the invention is established by arranging end blocks as junction elements on the faces of the collector block. This enables a compact structure of the entire tubing (collector lines, junction elements) to be established. The end blocks can serve for fastening the heat exchanger registers by accommodating the collector lines and for fastening the heat exchanger as a whole by additional mounting of corresponding holders. Also, assembly and standardization of the components are made easier.
Accordingly, the end blocks can be varied for different variants of the heat exchanger regarding capacity, arrangement, and integration into the refrigerant circuit, particularly because of the fact that they are composed of junction plates and end plates.
In a further embodiment of the invention, junction channels are provided in the junction plates according to the position of the collector lines to be connected, the junction channels being closed by the end plates. In this way, an advantageous connection of the individual collector lines of the collector block is established, and easy manufacture as well as a standardized modular structure of the heat exchanger are enabled.
In an embodiment of the invention, heat exchanger ports are integrated into the end blocks. This enables a more compact design of the heat exchanger and, particularly due to the reduced number of components, an assembly-friendly manufacture.
The heat exchanger is established to comprise components manufactured as modules. Due to the modular structure, simple design of the heat exchanger with different capacities, dimensions, and connection variants can readily be established.
With particular advantage, the heat exchanger can be used in air conditioning units with the refrigerant R744. R744 (carbon dioxide) requires high operational pressures, which are withstood by the heat exchanger particularly due to the fact that the multiple-channel flat tubes and collector blocks can be established to be high-pressure resistant, provided the components are accordingly dimensioned.
Good distribution of the liquid refrigerant can be reached due to the arrangement of the heat exchanger tubes in three rows, and the combination to heat exchanger registers according to the invention. It is particularly advantageous that this ensures a homogeneous temperature distribution of the air flow leaving the heat exchanger.
An advantage of the solution according to the invention is further that the heat exchanger-caused pressure losses are minimized, and the design of the heat exchanger is simplified. Also, due to the modular structure, the heat exchanger can easily be designed in different sizes, and easily extended or made smaller, hence being flexibly adaptable to the respective conditions.
In one embodiment, a heat exchanger for use in a vehicle air conditioning system includes a plurality of heat exchanger registers. Each of the heat exchange registers has a top collector line and a bottom collector line with a plurality of heat exchanging tubes disposed therebetween. One of the heat exchanger registers has a first port adapted to receive a refrigerant from a refrigerant circuit. An other of the heat exchanger registers has a second port adapted to deliver the refrigerant to the refrigerant circuit. The heat exchanger registers are adapted to transfer heat from an air flow passing thereby to the refrigerant flowing therethrough. The heat exchanger further includes a plurality of junction elements in fluid communication with the heat exchanger registers. Each of the junction elements is disposed between one of a pair of the top collector lines and a pair of the bottom connector lines. The junction elements have a hydraulic flow area that militates against pressure losses in the heat exchanger.
In another embodiment, a vehicle air conditioning system includes the heat exchanger of the invention in fluid communication with a refrigerant circuit, for example, a circuit in an R744-system.
In a further embodiment, the heat exchanger includes a first heat exchanger register having a first top collector line and first bottom collector line with a plurality of first heat exchanging tubes disposed therebetween. The first top collector line having a first port adapted to receive a refrigerant from a refrigerant circuit. The heat exchanger includes a second heat exchanger register having a second top collector line and a second bottom collector line with a plurality of second heat exchanging tubes disposed therebetween. The second top collector line is in fluid communication with the first top collector line with a top junction element. The heat exchanger further includes a third heat exchanger register having a third top collector line and a third bottom collector line with a plurality of third heat exchanging tubes disposed therebetween. The third bottom collector line is in fluid communication with the second bottom collector line is in fluid communication with a bottom junction element. The third top collector line has a second port adapted to deliver the refrigerant to the refrigerant circuit. The top and bottom junction elements having hydraulic flow areas that militate against pressure losses in the heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the heat exchanger with three heat exchanger registers;

FIG. 2 is a fragmentary schematic diagram with a junction tube socket and integration of evaporator tubes;

FIG. 3 is a porting variant of the heat exchanger with a port extension line;

FIG. 4 is a schematic diagram of a collector block and junction hole;

FIG. 5 is an exploded schematic diagram of a collector block and an end block including a junction plate and an end plate; and

FIG. 6 is an exploded schematic diagram showing an integration of evaporator tubes with three flow channels into collector lines.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description and appended drawings describe and illustrate various embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner.
In FIG. 1, a schematic diagram of a heat exchanger with three heat exchanger registers 1, 2, 3 is shown. Evaporator tubes 9, typically equipped with fins for extending the heat transfer surface, each are connected to the collector lines 7 by soldering or brazing. The collector lines 7 of the heat exchanger registers 1, 2, 3 each are closed on one side, for example by a cap soldered or brazed on. Ports of the collector lines 7 each are at opposite ends. At the first heat exchanger register 1 and third heat exchanger register 2, the ports are arranged alternating.
According to FIG. 1, a port of the first heat exchanger register 1, this port at the same time being the port 4 of the heat exchanger for its integration into the refrigerant circuit, is arranged on the right side at the bottom collector line 7. Here, the liquid refrigerant enters the first heat exchanger register 1 and spreads over the individual, parallel passed evaporator tubes 9. The other port of the heat exchanger register 1 is arranged on the left side of the top collector line 7.
From there, through the junction element 6 (e.g., a 180° tube bend soldered or brazed on), the junction to the second heat exchanger register 3 is established. Again the evaporator tubes 9 arranged in parallel and passed in parallel are integrated into the collector lines 7. The port of the bottom collector line 7 here is also on the left side. Therefore, the flow passing the evaporator tubes 9 close to the port is somewhat more intense than in the evaporator tubes 9 that are more distant to the ports. Again the bottom port is connected to the port of the third heat exchanger register 2 through a junction element 6 (180° tube bend). The parallel arranged evaporator tubes 9 are homogeneously passed and brought together in the top collector line 7. The second port is on the right side of the collector line 7 that is diagonally opposite to the other port and at the same time serves as the heat exchanger port 5 of the heat exchanger for its integration into the refrigerant circuit.
On its path through the evaporator tubes 9 of the heat exchanger registers 1, 2, 3, the refrigerant due to the heat absorbed from the air flow 18 evaporates completely or is overheated, depending on process conduction, thereby cooling the air flow 18. The air flow 18 flows opposite to the refrigerant flow from the third/last heat exchanger register 2 to the first heat exchanger register 1. The ports of the heat exchanger registers 1, 2, 3 are arranged such that right ports can be replaced with left ports and top collector lines 7 with bottom collector lines 7, and vice versa.
In another embodiment, according to FIG. 2, the junction elements 6 are established as junction tube sockets 8. They are accordingly adapted to the shape of the circumferential surfaces of the collector lines 7 and, for example, brazed to them. Because the junction tube sockets 8 are disposed between the collector lines 7, no additional space is required. By additional mounting of a port extension line 10, as shown in FIG. 3, both ports 4, 5 of the heat exchanger can be immediately brought together, for example as shown by the location of port 4′ adjacent port 5. This enables a port arrangement that further simplifies assembly of the heat exchanger.
It is advantageous to establish the collector lines 7 according to FIG. 4. Instead of using tubes, the top collector lines 7 and bottom collector lines 7 each are integrated to form a collector block 11, the tube lines being formed, for example, by drilling or milling. The collector block can also be manufactured from an extruded profile. The evaporator tubes 9 are soldered or brazed into the port sockets 12. Also the junction elements 6 can be formed in the collector block 11 as junction holes 13 and possibly closed by plugs. The compact design of the heat exchanger and the possibilities of simple attachment to the collector block 11 are advantageous.
In FIG. 5 end blocks comprising a junction plate 14 with junction channel 15 and an end plate 16 are attached to the faces of the collector blocks 11 as junction elements. The junction channel 15 is arranged in the junction plate 14 such that the desired flow between the collector lines 7 is enabled. Where no junction channel 15 is milled in the junction plate 14, no refrigerant can flow. The end plate 16 closes the junction channel 15. The junction plate 14 and the end plate 16 are connected to the collector block 11, for example, using screws and seals.
In another embodiment, additional collector tube port plates allow to use the end blocks also for collector lines 7 that are established as tubes. The collector tube port plates have the dimensions of the junction plates 14 and are provided with accordingly arranged holes for the connection to the collector lines 7. They are connected to the collector lines 7, for example, by brazing. The junction plates 14 following the collector tube connection plates release the desired flow options by respective arrangement of the junction channels 15.
In FIG. 6 the evaporator tubes 9 are established such that an evaporator tube 9 provides one or several flow channels 17 per heat exchanger register 1, 2, 3.
While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes may be made without departing from the scope of the disclosure, which is further described in the following appended claims.

Claims

1. A heat exchanger for use in a vehicle air conditioning system, the heat exchanger comprising:

a plurality of heat exchanger registers, each of the heat exchanger registers having a first collector line and a second collector line, one of the heat exchanger registers having a first port adapted to receive a refrigerant fluid from a refrigerant circuit and an other of the heat exchanger registers having a second port adapted to deliver the refrigerant fluid to the refrigerant circuit, the heat exchanger registers adapted to transfer heat from air flowing therearound to the refrigerant fluid flowing therethrough;

a plurality of tubes disposed between the first collector lines and the second collector lines adapted to provide fluid communication therebetween; and

a plurality of junction elements, each of the junction elements disposed between one of a pair of the first collector lines and a pair of the second connector lines to provide fluid communication therebetween.

2. The heat exchanger according to claim 1, wherein a hydraulic flow area of one of the junction elements is at least 60% of a hydraulic flow area of one of the first collector lines and the second collector lines.

3. The heat exchanger according to claim 1, wherein a hydraulic flow area of one of the junction elements is between about 75% and about 110% of a hydraulic flow area of one of the first collector lines and the second collector lines.

4. The heat exchanger according to claim 1, wherein one of the junction elements is a 180° tube bend disposed at an end of one of the pair of the first collector lines and the pair of the second connector lines.

5. The heat exchanger according to claim 1, wherein one of the junction elements is a junction tube socket in fluid communication with openings formed in one of the pair of the first collector lines and the pair of the second collector lines.

6. The heat exchanger according to claim 1, wherein the heat exchanging tubes are multiple-channel flat tube evaporators.

7. The heat exchanger according to claim 1, further comprising a port extension line in communication with one of the first port and the second port, the port extension line adapted to dispose one of the first port and the second port adjacent an other of the first port and the second port.

8. The heat exchanger according to claim 1, wherein at least one of the first collector lines and the second collector lines is formed in a collector block, the collector block having a plurality of port sockets formed therein adapted to receive the tubes and provide a fluid communication between at least one of the first collector lines and the second collector lines and the tubes.

9. The heat exchanger according to claim 8, wherein the collector lines are formed by one of drilling and milling.

10. The heat exchanger according to claim 8, wherein at least one of the junction elements is a junction hole formed in the collector block.

11. The heat exchanger according to claim 8, further comprising a junction plate disposed at an end of the collector block, at least one of the junction elements formed as a junction channel in a junction plate.

12. The heat exchanger according to claim 11, further comprising an end plate disposed adjacent the junction plate adapted to seal the junction channel.

13. The heat exchanger according to claim 8, further comprising an end block disposed at an end of the collector block, one of the first ports and the second ports formed in the end block.

14. The heat exchanger according to claim 1, wherein the refrigerant fluid is carbon dioxide.

15. The heat exchanger according to claim 1, wherein one of the tubes is coupled to at least one of the first collector lines and the second collector lines by one of soldering and brazing.

16. A vehicle air conditioning system, comprising:

a refrigerant circuit; and

a heat exchanger in fluid communication with the refrigerant circuit, the heat exchanger further comprising:

a plurality of heat exchanger registers, each of the heat exchanger registers having a first collector line and a second collector line, one of the heat exchanger registers having a first port adapted to receive a refrigerant fluid from the refrigerant circuit and an other of the heat exchanger registers having a second port adapted to deliver the refrigerant fluid to the refrigerant circuit, the heat exchanger registers are adapted to transfer heat from air flowing therearound to the refrigerant fluid flowing therethrough;

17. The vehicle air conditioning system of claim 16, wherein the refrigerant fluid is carbon dioxide.

18. The vehicle air conditioning system of claim 16, wherein a flow of air is in a direction opposite a direction of a flow of the refrigerant fluid.

19. A heat exchanger for use in a vehicle air conditioning system, the heat exchanger comprising:

a first heat exchanger register having a first collector line and a second collector line, the first heat exchanger having a first port adapted to receive a refrigerant fluid from a refrigerant circuit;

a second heat exchanger register having a first collector line and a second collector line, in fluid communication with the first heat exchanger register;

a third heat exchanger register having a first collector line and a second collector line in fluid communication with the second heat exchanger register, the first collector line having a second port adapted to deliver the refrigerant to the refrigerant circuit;

a plurality of tubes disposed between the first collector line and the second collector line, adapted to provide fluid communication therebetween; and

20. The heat exchanger according to claim 19, wherein the first port of the first heat exchanger register and the second port of the third heat exchanger register are arranged diagonally from one another, whereby the ports of each of the first heat exchanger register and the third heat exchanger register are configured to be connected to the refrigerant circuit.