GB1601954A

GB1601954A - Heat exchanger

Info

Publication number: GB1601954A
Application number: GB2340977A
Authority: GB
Original assignee: Covrad Ltd
Current assignee: Covrad Ltd
Priority date: 1978-05-15
Filing date: 1978-05-15
Publication date: 1981-11-04

Description

(54) HEAT EXCHANGER (71) We, COVRAD LIMITED, a British Company, of Sir Henry Parkes Road, Canley, Coventry, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to heat exchangers of the kind including tubes through which heat exchange fluid is passed, the tubes having internal secondary heat exchange surfaces.

According to the invention a heat exchanger comprises a thin-walled (as herein defined) tube, within and extending along which is a sinusoidal corrugated strip of material, the corrugations each extending in the lengthwise direction of the tube and there being two or more corrugations across the width of the tube, the apices of the corrugations being connected to the tube, and the tube and the strip being formed of material with a relatively high thermal conductivity compared with that of steel. For example, the material may be brass.

By 'thin-walled' is meant a wall thickness of less than 8 thousandths of an inch as compared with comparable tubes of 20 to 30 thousandths of an inch.

Preferably the tube is a lockseam tube in which a strip of metal is formed into a closed loop in its width-wise direction and the edges are locked together to form a seam by overlapping the edges.

Conveniently the corrugated strip is connected to the tube by solder.

The tube and corrugated strip may be assembled into a heat exchange core by locating a plurality of the tubes with the corrugated strips already inserted through a plurality of fin elements transverse to the tubes, conveniently thin sheets arranged parallel to one another, to provide secondary heat exchange surfaces over which a heat exchange fluid is passed to set up heat transfer with other fluid passing through the tubes.

The assembled core may be dipped into a bath of molten solder to provide joints between the tubes, the fin elements and the corrugated material. Such joints provide good thermal contact between the tubes and the corrugated material and the assembly is strengthened by the corrugated material acting as struts for the tubes.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings in which: Fig. 1 is an end view of a heat exchanger tube, and Fig. 2 is a perspective view of part of a heat exchanger incorporating tubes according to Fig. 1.

Referring to the drawings and firstly to Fig. 1, a lockseam tube 10 is of generally flattened cross-section and is formed of a thin, about W8 thousandths of an inch thick, strip of brass of which the edges are brought together to form a closed loop and are locked together at 11 to provide a seam by forming hooked portions which are engaged with one another.

A strip 12 of sinusoidal corrugated material, preferably brass having a thickness of 98 thou., is inserted along the tube 10 so that the corrugations extend lengthwise of the tube with, in this case, three corrugations across the width of the tube. The crests or apices of the sinusoidal corrugations are closely adjacent or in contact with the inner surfaces of the tube after insertion and the corrugated strip 12 serves as a secondary heat exchange surface.

After assembly of several tubes 10 with corrugated strips 12 the tubes are each inserted through fin elements 14 (Fig. 2) so that the fin elements are parallel to one another and the tubes are at right-angles to the elements and parallel to one another. The assembly of fin elements 14 and tube is then dipped into a bath of molten solder to provide joints between the corrugated strips 12 and the tube 10 and between the tubes and the fin elements 14. The solder ensures that the strips 12 strengthen the tubes 10 by acting as struts across the thin walls of the tubes. Moreover the solder improves the thermal contact between the strips and the tubes and between the tubes and the fin elements.

The assembled heat exchanger core or matrix is employed in a heat exchanger by passing a first fluid through the tubes and a second fluid around the tubes and over the fins to set up a heat exchange relationship between the two fluids. The construction of the tubes is such that even though the tubes are thin-walled, a pressure of up to 200 p.s.i.

can be maintained in the tubes.

WHAT WE CLAIM IS: 1. A heat exchanger comprising a thinwalled (as herein defined) tube, within and extending along which is a sinusoidal corrugated strip of material, the corrugations each extending in the lengthwise direction of the tube and there being two or more corrugations across the width of the tube, the apices of the corrugations being connected to the tube, and the tube and the strip being formed of material with a relatively high thermal conductivity compared with that of steel.

2. A heat exchanger according to claim 1 wherein the tube is a lockseam tube in which a strip of metal is formed into a closed loop in its width-wise direction and the edges are locked together to form a seam by overlapping the edges.

3. A heat exchanger according to claim 1 or 2 wherein the corrugated strip is connected to the tube by solder.

4. A heat exchanger according to any one of the preceding claims comprising a plurality of said tubes each fitted with said corrugated strip, the tubes being located through a plurality of fin elements transverse to the tubes, the fin elements acting as secondary heat exchange surfaces over which heat exchange fluid can pass in heat exchange relationship with other fluid passing through the tubes.

5. A heat exchanger according to claim 4 wherein the fin elements are thin sheets of material lying parallel to one another.

6. A heat exchanger according to claim 4 or 5 wherein the tubes and the fin elements connected to one another by solder applied by dipping the assembled tubes and fin elements in molten solder.

7. A heat exchanger according to any one of the preceding claims wherein the tube or tubes and the associated corrugated strip or strips are formed of brass.

8. A heat exchanger according to any one of the preceding claims wherein the corrugated strip or strips have a thickness in the range 6 to 8 thousandths of an inch.

9. A heat exchanger substantially as described with reference to Fig. 1 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. elements. The assembled heat exchanger core or matrix is employed in a heat exchanger by passing a first fluid through the tubes and a second fluid around the tubes and over the fins to set up a heat exchange relationship between the two fluids. The construction of the tubes is such that even though the tubes are thin-walled, a pressure of up to 200 p.s.i. can be maintained in the tubes. WHAT WE CLAIM IS:

1. A heat exchanger comprising a thinwalled (as herein defined) tube, within and extending along which is a sinusoidal corrugated strip of material, the corrugations each extending in the lengthwise direction of the tube and there being two or more corrugations across the width of the tube, the apices of the corrugations being connected to the tube, and the tube and the strip being formed of material with a relatively high thermal conductivity compared with that of steel.