Device For Heat Exchange And Method For Producing One Such Device

Abstract

The invention relates to a device for heat exchange, said device comprising a flow device and a collection and/or distribution device connected to the flow device at a connection point. The flow device has a pre-determined length and a flat tubular cross-section, and a fluid under a high pressure, for example an operating pressure of approximately 125 bar, flows through the same. Said flow device has a linear course over the entire length thereof, along a longitudinal axis thereof. The long side of the flat tubular cross-section of the flow device is approximately between 5 mm and 6.1 mm, and is at an angle of approximately 90°, at the connection point, in relation to a main direction of extension of the collection and/or distribution device.

Description

Further advantages and embodiments of the present invention can be appreciated from the accompanying drawings, in which:

FIG. 1 is a partial representation of a device in accordance with the invention for the exchange of heat, in the form of a heat exchanger for a gas cooler;

FIG. 2 is a representation, which depicts a relationship between geometrical dimensions of the component parts of a device in accordance with the invention for the exchange of heat, in the form of a heat exchanger for a gas cooler;

FIG. 3 is a graphical representation with a relationship between a block depth of a two-row gas cooler with flat tubes in accordance with the invention and a flat tube depth of a tube in accordance with the invention for two bursting pressures;

FIG. 4 is a graphical representation with a relationship between a flat tube depth of a tube in accordance with the invention and a block depth of a two-row gas cooler with flat tubes in accordance with the invention for two bursting pressures;

FIG. 5 is a graphical representation with a relationship between an air face velocity and a gas cooler output for a gas cooler with flat tubes in accordance with the invention and for a comparable gas cooler with twisted flat tubes in accordance with a first gas cooler matrix;

FIG. 6 is a graphical representation with a relationship between an air face velocity and a gas cooler output for a gas cooler with flat tubes in accordance with the invention and for a comparable gas cooler with twisted flat tubes in accordance with a second gas cooler matrix;

FIG. 7 is a graphical representation with a relationship between a flat tube width and a weight of a gas cooler matrix for different gas cooler matrices;

FIG. 8 is a graphical representation with a relationship between an air face velocity and a weight-related gas cooler output for a gas cooler with flat tubes in accordance with the invention and for a comparable gas cooler with twisted flat tubes in accordance with a first gas cooler matrix;

FIG. 9 is a graphical representation with a relationship between an air face velocity and a weight-related gas cooler output for a gas cooler with flat tubes in accordance with the invention and for a comparable gas cooler with twisted flat tubes in accordance with a second gas cooler matrix;

FIG. 10 is a partial representation of a conventional heat exchanger for a gas cooler having a plurality of conventional twisted flat tubes in accordance with the prior art.

FIG. 1 depicts a section through a two-row high-pressure gas cooler 110, abbreviated here to gas cooler.

The two-row gas cooler 110 in accordance with this embodiment exhibits a tube interconnection from 29/31-31/29 and overall dimensions of a heat exchanger matrix in the order of approximately B×H=462.0×660 mm². A block depth of the two-row gas cooler 110 is in the order of approximately 16 mm.

In FIG. 1, the reference designation 100 in each case relates to a (flat) tube of the two-row gas cooler 110 in accordance with the invention.

The flat tube 100 exhibits a tube length in the order of approximately 670 mm and a flat tubular cross section 101 with a long side, a flat tube depth of 5.8 mm, and a significantly shorter side, a flat tube width, of 1.5 mm in relation to this long side.

Moreover, the flat tube 100 exhibits a linear course for the tubes over the entire length of the tube along a longitudinal axis of the tube.

In the two-row gas cooler in accordance with the embodiment, the tubes 100 are arranged on two mutually parallel levels 102, 103.

Within each level 102, 103, the flat tubes 100 are also arranged parallel with one another at a distance of approximately 2 mm to 10 mm, preferably between 4 mm and 8 mm, and in particular approximately 6 mm.

Between two flat tubes 100 arranged in each case adjacent to and parallel with one another on a level 102, 103, corrugated ribs 106, in each case with a rib height in the order of approximately 6 mm, are arranged along the length of the tube and in the longitudinal direction 104 of the tubes 100.

The two-row gas cooler 110 in accordance with the embodiment exhibits an overall rib density of 75 ribs/dm. A preferred range for the density of the ribs is in the order of 65 to 85 ribs/dm.

A cooling medium under high pressure flows through the flat tubes 100 in the longitudinal direction 104, for which purpose in the flat tube 100 a plurality of flow channels 105 run essentially parallel with the longitudinal direction 104 and the longitudinal axis of the flat tube 100.

A couple of collection tanks 120 exhibiting two collection tubes 123, 124 are connected to each flat tube end 121 at a connection point provided for the purpose, in order to extend in a direction, a principal direction of extension, perpendicular to the longitudinal direction 104 of each tube 100. A cooling medium under high pressure also flows through these.

Consequently, the flat tubular cross section 101 and the long side of the flat tubular cross section 101 of the tube 100 exhibit, at each connection point, a predetermined angle in the order of approximately 90° in relation to the principal direction of extension of the collection tank 120.

A recess for the connection of the flat tube 100 is provided at the connection point on the side of the collection tank 120. A cross section through the recess is adapted in this case to the cross section 101 of the flat tube 100. In addition, the recess exhibits a supplementary formed area, in the form of a guide taper for the flat tubes 100.

The expression connection to one another is used to denote a connection of a kind such that a fluid in liquid and/or gaseous form, such as the cooling medium in this case, is able to flow through this connection in a liquid-tight and/or gas-tight manner.

Corresponding methods for producing a tight connection of this kind, such as soldering, welding and/or adhesive bonding, or combinations thereof, are familiar from the prior art.

The collection tanks 120 and the collection tubes 123, 1124 in each case exhibit a tubular cross section 122, in conjunction with which an internal diameter 200 of the tubular cross section 122 is approximately equal to the tube depth of the flat tube 100. A collection tube wall thickness 201 is dependent on a stipulated bursting pressure.

FIG. 2 depicts geometrical relationships for he purpose of determining the block depth.

The block depth T(Ges) is determined from:

T(Ges)=2*T(F1)+2×d(wall, collection tube)+b(gap),

where T(Fl) is the flat tube depth, d(wall, collection tube) is a wall thickness of a collection tube, and d(gap) is a gap between the two collection tubes.

FIG. 3 is a graphical representation with a relationship between a block depth of a two-row gas cooler with flat tubes in accordance with the invention and a flat tube depth of a flat tube in accordance with the invention for two bursting pressures, namely 270 bar and 360 bar.

The graphical relation depicted here is based on the fact that b(gap)=0.8 mm, and d(wall, collection tube) is determined by

d(wall, collection tube)=0.1×p(burst)*T(F1)/(2*s),

where p(burst) designates the bursting pressure, and s is a limit of elasticity of a collection tube material. s is assumed in the present case to have a value of 50 N/mm² (AA 3003 mod).

It can be appreciated from FIG. 3 that the maximum flat tube depth T(Fl) can be =5.9 mm for a block depth of 16 mm and a bursting pressure of 270 bar. For a bursting pressure of 360 bar, the maximum flat tube depth T(Fl)=5.5 mm.

The flat tube depth T(Fl)<6 mm is thus adequate for a bursting pressure of 270 bar for linear flat tubes in the case of two-row high-pressure gas coolers with a block depth of 16 mm.

Consideration must also be given here to the circumstance that, with decreasing flat tube depths T(Fl), a contact surface between a corrugated rib and the flat tube is reduced at a constant block depth. For this reason, at a block depth of 16 mm, the individual flat tube depth should also not be less than approximately 5 mm. Corresponding consideration must also be given to other total block depths.

It can also be appreciated from FIG. 3 that, for a block depth of 14 mm in the case of two-row gas coolers, a flat tube depth T(Fl)<5.20 mm is adequate for a bursting pressure of 270 bar in the case of linear flat tubes.

FIG. 4 is a graphical representation with a relationship between a flat tube depth of a tube in accordance with the invention and a block depth of a two-row gas cooler with flat tubes in accordance with the invention for two bursting pressures, namely 270 bar and 360 bar.

It can be appreciated from FIG. 4, for example, that, in the case of a bursting pressure of 270 bar (360 bar) and a block depth of 15 mm, a flat tube depth in the order of approximately 5.2 mm (5.6 mm) is adequate in the case of linear flat tubes.

FIGS. 5 and 6 depict a gas cooler output for a gas cooler plotted against an air face velocity under stipulated marginal conditions.

In FIG. 5, 2 two-row high-pressure gas coolers with a rib density of 75 ribs/dm, a rib height of 6 mm, a block depth of 16 mm and identical tube interconnections 29/31-31/29 are compared with one another.

Gas cooler 1 exhibits conventional flat tubes with twisted flat tube ends and with a flat tube depth of 7 mm. The dimensions of the heat exchanger matrix of this gas cooler 1 are B×H=462.0×650.0 mm² for an end face F(St)=30.0 dm².

Gas cooler 2 exhibits the flat tubes in accordance with the invention with a linear course for the tubes and with a flat tube depth of 5.8 mm. The dimensions of the heat exchanger matrix of the gas cooler 2 are B×H=462.0×664.0 mm² for an end face F(St)=30.7 dm².

The larger end face of the gas cooler 2 means that the disadvantage of the smaller flat tube depth and the associated reduced contact surface between the corrugated rib and the flat tube can be more or less equalized. The gas cooler 2 exhibits a greater pressure drop on the cooling medium side for an identical mass flow rate.

FIG. 6 compares 2 two-row high-pressure gas coolers with a rib density of 75 ribs/dm, a rib height of 4.5 mm, a block depth of 16 mm and identical tube interconnections 37/40-40/37 with one another.

Gas cooler 1 exhibits conventional flat tubes with twisted flat tube ends and with a flat tube depth of 7 mm. The dimensions of the heat exchanger matrix of this gas cooler 1 are B×H=458.8×650.0 mm² for an end face F(St)=29.8 dm².

Gas cooler 2 exhibits the flat tubes in accordance with the invention with a linear course for the tubes and with a flat tube depth of 5.8 mm. The dimensions of the heat exchanger matrix of the gas cooler 2 are B×H=458.0×664.0 mm² for an end face F(St)=30.5 dm².

The larger end face of the gas cooler 2 means that the disadvantage of the smaller flat tube depth and the associated reduced contact surface between the corrugated rib and the flat tube can be more or less equalized. The gas cooler 2 exhibits a higher pressure drop on the cooling medium side for an identical mass flow rate.

FIG. 7 is a graphical representation with a relationship between a flat tube width and a weight of a gas cooler matrix for different gas cooler matrices.

The relationships for a flat tube in accordance with the invention having a flat tube depth of T(Fl)<6 mm and for a conventional flat tube having a larger flat tube depth, namely T(Fl)=7 mm are depicted in FIG. 7.

The relationships are depicted in each case for flat tube widths of 1.4 mm and 1.6 mm and for two corrugated rib heights of 4.5 mm and 6 mm for a rib density of 75 ribs/dm. The thickness of a single corrugated rib is 0.1 mm.

It can be appreciated from FIG. 7 that the weight of gas coolers having a flat tube depth T(Fl)<6 mm in accordance with the invention is significantly smaller.

FIGS. 8 and 9 depict a weight-related gas cooler output, which is arrived at by dividing the gas cooler output by the weight of the heat exchanger matrix, and by plotting this against the air face velocity under stipulated marginal conditions.

The gas cooler output depicted here relates to the gas cooler already dealt with in FIG. 5 and FIG. 6.

It can be appreciated from FIG. 8 and FIG. 9 that the weight-related gas cooler output for the two gas coolers with the flat tubes in accordance with the invention having a flat tube depth T(Fl)<6.1 mm is significantly larger in comparison with the two gas coolers with conventional flat tubes having a flat tube depth of 7 mm.

The present invention is particularly suitable for application to the coolers or auxiliary heaters of a high-pressure cooling circuit. A design of the heat exchanger matrix in each case is not restricted to the geometries described above. It can be selected freely in the context of the flat tube geometry in accordance with the invention and the bursting pressure requirements.

Although the present invention has been explained fully in conjunction with preferred embodiments with reference to the accompanying drawings, numerous variations and modifications will be obvious to a person skilled in the art, all of which come within the scope of the present invention, as laid down in the accompanying patent claims.

Claims

1. A device for the exchange of heat, having at least one flow device and at least one collection and/or distribution device connected to the at least one flow device at a connection point, in conjunction with which the at least one flow device exhibits a flat tubular cross section having one long side and one short side in relation to the long side, as well as a predetermined flow device length, in conjunction with which a fluid under high pressure is capable of flowing through the at least one flow device and the at least one collection and/or distribution device, wherein the at least one flow device exhibits a linear course over the entire length of the flow device along a longitudinal axis of the flow device, and in that the long side of the flat tubular cross section exhibits a length in the order of approximately 5 mm to 6.1 mm, and in particular 5 mm to 5.9 mm, and in that at the connection point, the long side of the flat tubular cross section of the flow device exhibits an angle of approximately 90° in relation to a principal direction of extension of the collection and/or distribution device.

2. A device as claimed in claim 1, wherein the short side of the flat tubular cross section of the flow device exhibits a length of approximately 1 mm to 2 mm and/or the length of the flow device is approximately 200 mm to 800 mm.

3. A device as claimed in claim 1, wherein the flow device exhibits at least one internal flow channel running essentially parallel with the longitudinal axis of the flow device, and preferably a plurality of internal flow channels running essentially parallel with the longitudinal axis.

4. A device as claimed in claim 3, wherein, in its cross section, the at least one flow channel exhibits a form which is essentially circular, elliptical, polygonal or rectangular, or a combination of mixed forms of these.

5. A device as claimed in claim 1, wherein the device exhibits a plurality of the flow devices, each of which is connected to the at least one collection and/or distribution device and/or which are arranged essentially on at least one level and/or are arranged essentially parallel with one another.

6. A device as claimed in claim 5, wherein the plurality of flow devices are arranged on two levels.

7. A device as claimed in claim 1, wherein the device exhibits two collection and/or distribution devices, of which each is connected to one end of the at least one flow device.

8. A device as claimed in claim 1, wherein the at least one collection and/or distribution device exhibits a tubular cross section, in conjunction with which an internal diameter of the tubular cross section of the collection and/or distribution device is approximately equal to the long side of the flat tubular cross section of the flow device.

9. A device as claimed in claim 1, wherein the fluid flowing through the at least one collection and/or distribution device is a cooling medium and/or is under a pressure of approximately 125 bar.

10. A cooler, in particular a gas cooler, and/or an auxiliary heater comprising a device as claimed in claim 1, wherein the cooler and/or the auxiliary heater exhibits a plurality of the flow devices, each of which is connected to the at least one collection and/or distribution device and/or which are arranged essentially on at least one level and/or are arranged essentially parallel with one another, and in that the cooler and/or the auxiliary heater exhibits a plurality of ribs, which are arranged between neighboring flow devices essentially perpendicular to the longitudinal direction of the flow device in each case, in order to promote an exchange of heat between the air and the fluid.

11. A device for the air conditioning of air introduced into the interior of a motor vehicle, having at least a compressor, an evaporator and/or auxiliary heater, an expansion valve and a cooler, comprising at least one auxiliary heater and/or a cooler is as claimed in claim 10.

12. A method for producing a device for heat exchange, comprising: producing a connection at a connection point between at least one flow device and one collection and/or distribution device, which connection is selected from a group consisting of soldered, welded or adhesive bonded connections, wherein the at least one flow device exhibits a flat tubular cross section having a long side with a length in the order of approximately 5 mm to 6.1 mm, and in particular 5.9 mm, and having a short side in relation to the long side;exhibits a predetermined flow device length;accommodates the flow of a fluid under high pressure, andexhibits a linear course over the entire length of the flow device along a longitudinal axis of the flow device,