GB2379730A

GB2379730A - A plate heat exchanger for a glycol/water circuit and refrigerant circuit of a motor vehicle

Info

Publication number: GB2379730A
Application number: GB0216042A
Authority: GB
Inventors: Bernd Dienhart; Joern Froehling; Peter Heyl
Original assignee: Visteon Global Technologies Inc
Current assignee: Visteon Global Technologies Inc
Priority date: 2001-07-12
Filing date: 2002-07-11
Publication date: 2003-03-19
Anticipated expiration: 2022-07-11
Also published as: DE10134761C2; GB2379730B; DE10134761A1; GB0216042D0; US20030015310A1

Abstract

A plate heat exchanger 1 comprises flat plates 2 having flow channels (3, fig 2) preferably of a meandering manner for a refrigerant and circular, oval, elliptical, rectangular or an elongated hole shaped headers integrated in the plate 2. Plates 4 having parallel flow channels for a glycol / water mixture (5, fig 3) and headers arranged outside and on either side of the plate 4 and divided into separate chambers by separators. The wall thickness of plates 2, 4 may be 0.2mm to 5mm and are connected by soldering, brazing or welding and plates 2 are preferably arranged alternately to plates 2. Flow channels for plates 2, 4 may be circular, semicircular, wedge-shaped, fibbed or non-ribbed and may be single-flow or multi-flow with hydraulic diameters of the flow channels for refrigerant may be 0.1mm to 4mm and 1mm to 6mm for the glycol / water mixture. The flow may be countercurrent, cross, parallel or concurrent. The refrigerant may be carbon dioxide, tetrafluoroethane, or propane.

Description

- 1 HEAT EXCHANGER, PARTICULARLY FOR THERMAL COUPLING OF A

GLYCOL/WATER CIRCUIT AND A REFRIGERANT CIRCUIT

The invention relates to a heat exchanger, particularly 5 for thermal coupling of a glycol/water circuit and a refrigerant circuit in motor vehicles.

Heat exchangers are apparatuses, or components, in that heat is indirectly transferred from a fluid mass flux with 10 a higher temperature to another fluid mass flux with a lower temperature. Both mass fluxes pass through the heat exchanger without mixing. They are separated from each other. 15 The heat which is generated in the combustion process of motor vehicles with internal combustion engines is disposed to the environment in the cooling circuit. Under certain operational conditions it is useful to exploit a portion of this heat to be disposed for the heating of the 20 passenger cell. The problem is the low temperature of this waste heat. A heat pump makes it possible, however, to easily use this heat for the heating of the passenger cell. To do this it is necessary to transfer the heat from the glycol/water circuit to the refrigerant circuit of the 25 heat pump.

The state-of-the-art knows a number of heat exchangers for various applications.

There are particular requirements of heat exchangers which 30 also function at high fluid pressures of the mass fluxes.

2 - Heat exchangers according to the generic term of this invention are used for such an application.

5 For the use of different refrigerants in cooling plants/heat pump processes heat exchangers are known that work with very small flow crosssections and filling capacities in the heat exchangers.

10 Particularly from DE 100 07 159 Al a heat exchanger is known for the application with refrigerants at high pressures. The refrigerant passes through the heat exchanger in flat tubes having refrigerant channels of small diameters. Distances between these flat tubes are 15 produced by means of ribs. These flat tubes form an air-

refrigerant heat exchanger as evaporator in a cooling plant. Such a heat exchanger is not suitable to be used according 20 to the invention for thermal coupling of a glycol/water circuit to a refrigerant circuit.

Due to the collector and ribs the physical size of such a heat exchanger as an additional heat exchanger in a motor 25 vehicle is not acceptable.

Also a heat exchanger consisting of flat tubes according to DE 197 19 260 C1 is not suitable for thermal coupling of a glycol/water circuit to a refrigerant circuit, 30 whereby the flat tubes for the refrigerant are tailored to

- 3 - be used at high pressures, for example in refrigerant circuits with carbon dioxide as the refrigerant.

It is the objective of the invention to provide a heat 5 exchanger, particularly for the heat exchange between a refrigerant and a glycol/water mixture such that this heat exchanger has a small physical size and works at high rates of transferred heat fluxes, whereby simultaneously the safety requirements are fulfilled also for the use of 10 high-pressure refrigerants.

According to the invention this problem is solved by the fact that a heat exchanger, particularly for thermal coupling of a glycol/water circuit and a refrigerant 15 circuit in motor vehicles, is designed as a plate heat exchanger and has plates with flow channels for the refrigerant and plates different from said plates with flow channels for the glycol/water mixture, whereby the collector for the refrigerant is integrated into the 20 plates and the collector for the glycol/water mixture is arranged outside the plates on the lateral sides or front side of the heat exchanger, thereby arranged on the same plane with the collector or offset by 90 .

25 According to the concept of this invention, the heat exchanger is made as a type of plate heat exchanger.

Alternately, the refrigerant or the glycol/water mixture flows in a plane, whereby the heat between the refrigerant and the glycol/water mixture is transferred in cross 30 and/or parallel flow, countercurrent flow, cross

- 4 countercurrent flow, or cross concurrent flow. The described heat exchanger has connections for refrigerant inflow, refrigerant outflow, glycol/water mixture inflow, and glycol/water mixture outflow, or is directly connected 5 to another heat exchanger. That is, in particular, the environment heat exchanger/cooler of the glycol/water circuit. The heat exchanger is designed such that the safety 10 requirements are fulfilled due to small flow cross-

sections of the refrigerant channels and a small total filling volume of the heat exchanger.

The advantages of the heat exchanger according to the 15 invention are that a heat exchanger with a very small size is provided, which has a large heat-transferring surface and, due to its design satisfies the safety requirements for the application in a circuit with a refrigerant.

20 Further details, features and advantages of the invention ensue from the following description of examples of

embodiment with reference to the drawings. The figures show: 25 Fig. 1 Heat exchanger made of plates, perspective view; Fig. 2 Plate with flow channels for refrigerant; Fig. 3 Plate with flow channels for glycol/water mixture; Fig. 4 Heat exchanger, top view.

- s In Fig. 1 a heat exchanger 1 according to the invention is shown which is made of several plates 2, 4. The plates 2 for refrigerant have flow channels 3 for the refrigerant, the plates 4 for glycol/water mixture have flow channels 5 5 with the flow channels 3, 5 in the plates 2, 4 are designed single-flow or multiflow.

Advantageously, the plates 2, 4 of the heat exchanger 1 are made of flat material, in which the flow channels for 10 the refrigerant and the glycol/water mixture are created by a mechanical forming process, such as pressing or stamping, milling, etching or laser machining. Preferably, the plates 2, 4 are arranged alternately and form a plate pack. The wall thicknesses of the plates 2, 4 are 0.2mm to 15 5mm dependent on the application and the plates 2, 4 are connected by soldering, brazing or welding. The glycol/water mixture collectors 7 are arranged on either side of the plate pack.

20 In Fig. 2 a plate 2 with flow channels 3 for refrigerant is shown. The flow channels 3 pass through the plate 2 in a preferably meandering manner and connect the collectors for refrigerant 6 with each other.

Advantageously, the collector 6 for the refrigerant is 25 worked in the plate material. Depending on the application, refrigerant and geometrical conditions the collector 6 is designed circular, oval, elliptical, rectangular, or as an elongated hole.

30 The flow channels 3, 5 in the plates 2, 4 are circular,

- semicircular, wedge-shaped, ribbed or not ribbed with hydraulic diameters of the flow channels 3 for the refrigerant of O.lmm to 4mm and of the flow channels 5 for the glycol/water mixture lmm to 6mm.

5 The hydraulic diameter is defined as the product of the cross-sectional area multiplied by four, divided by the periphery of this area. Therefore, for circular cross-

sections the hydraulic diameter is equal to the diameter of the circle.

Fig. 3 shows a plate 4 with flow channels 5 for the glycol/water mixture. Further, distance pieces 8 are provided and the passage openings 9 for the refrigerant connect the collectors 6 of two plates 2 with each other.

15 The collectors 7 for the glycol/water mixture are provided on either side of the plate 4. They are connected in the shortest possible way by parallel flow channels 5 in the plate 4, which are designed linear. In a preferred embodiment of the invention the flow channels 5 in the 20 plate 4 are arranged angular to the outside edges, which extends the path between the collectors 7 for the same plate dimensions.

Fig. 4 shows the top view of an embodiment of the heat 25 exchanger 1 according to the invention. The collectors 7 for the glycol/water mixture are divided into different chambers by separators 10. Therefore, the glycol/water mixture passes through only part of the flow channels 5 in the plate 4 to the opposite collector 7 and from there 30 through other flow channels 5 in the same plate 4 back to

- 7 the collector 7.

Owing to the arrangement of the flow channels 3, 5 and the separators 10 in the heat exchanger 1 according to the 5 invention all types of flow like countercurrent flow, cross flow, parallel flow and concurrent flow can be realized partially or totally.

The heat exchanger according to the invention can, 10 particularly, be used with the refrigerants carbon dioxide tR744), tetrafluoroethane (R134a) and propane (R290).

NOMENCLATURE

15 1 Heat exchanger 2 Plate for refrigerant 3 Flow channel in the plate for the refrigerant 4 Plate for glycol/water mixture 5 Flow channel in the plate for the glycol/water 20 mixture 6 Collector for refrigerant 7 Collector for glycol/water mixture 8 Distance piece 9 Refrigerant passage 25 10 Separator

Claims

- 8 - CLAIMS

1. Heat exchanger, particularly for thermal coupling of a glycol/water circuit and a refrigerant circuit in motor 5 vehicles characterized in that the heat exchanger has plates with flow channels for the refrigerant and plates different from said plates with flow channels for the glycol/water mixture, whereby the collector for the refrigerant is integrated into the plates and the 10 collector for the glycol/water mixture is arranged outside the plates on the lateral sides or front side of the heat exchanger and this way arranged on the same plane with the collector 6 or offset by 90 .

15

2. Heat exchanger according to Claim 1 characterized in

that the flow channels and/or for the refrigerant and for the glycol/water mixture are designed single- or multi-

flow. 20

3. Heat exchanger according to Claim 1 or 2 characterized in that the cross-section of the flow channels for the refrigerant is designed in various ways and increases with decreasing density of the refrigerant passing the heat exchanger.

4. Heat exchanger according to any of the Claims 1 to 3 characterized in that the hydraulic diameter of the flow channels is O.lmm to 4mm.

30

5. Heat exchanger according to any of the Claims 1 to 3

- 9 characterized in that the hydraulic diameter of the flow channels is lmm to 6mm.

6. Heat exchanger according to any of the Claims 1 to 5 5 characterized in that the collector for the refrigerant in the plate is circular, oval, elliptical, rectangular, or as an elongated hole.

7. Heat exchanger according to any of the Claims 1 to 6 10 characterized in that the heat exchanger is made of several plates and these plates have wall thicknesses of 0.2mm to 5mm.

8. Heat exchanger according to any of the Claims 1 to 7 characterized in that the flow channels are designed circular, semicircular, wedge-shaped, ribbed or non-

ribbed.

9. Heat exchanger according to any of the Claims 1 to 8 20 characterized in that the refrigerant is led in the plates (2, 4) in the heat exchanger in countercurrent flow, cross flow and/or parallel flow relative to the glycol/water mixture. 25

10. Heat exchanger according to any of the Claims 1 to 9 characterized in that the collector is designed with separators.

11. A heat exchanger substantially as herein described 30 with reference to the accompanying drawings.