GB2033569A

GB2033569A - Heat exchanger

Info

Publication number: GB2033569A
Application number: GB7926797A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-03
Filing date: 1979-08-01
Publication date: 1980-05-21
Also published as: GB2033569B

Abstract

A heat exchanger comprising a plurality of elongate tubes (1) of generally rectangular cross-section through which ambient air can pass, the tubes (1) being spaced apart laterally to define therebetween spaces (10) of generally rectangular section through which air from a heating source may pass across the major surfaces (5) of the tubes. Adjacent tubes are preferably spaced apart by outwardly facing channel- section members (2), one located at each end of the tubes, which define ends of the spaces between adjacent tubes. The major surface of each tube may be generally trapezoidal in shape, the included angle of two sides of the trapezium being preferably 30 DEG . <IMAGE>

Description

SPECIFICATION Heat exchangers This invention relates generally to heat exchangers.

The invention is particularly applicable to systems, for example ventilation systems, or machines, for example tumble dryers, in which ambient air is drawn in to the system or machine, raised in temperature and discharged at an elevated temperature to waste.

In accordance with the present invention, there is provided a heat exchanger comprising a plurality of elongate tubes of generally rectangular cross-section through which ambient air can pass, said tubes being spaced apart laterally to define therebetween spaces of generally rectangular section through which air from a heating source may pass across the major surfaces of the tubes.

Adjacent tubes are preferably spaced apart by outwardly facing channel-section members, one located at each end of the tubes, which define ends of the spaces between adjacent tubes.

Preferably, the major surface of each tube is generally trapezoidal in shape, the included angle of two sides of the trapezium being preferably 30 .

The components of the heat exchanger of the invention are conveniently made of galvanised steel and welded together.

The invention also provides a system or machine incorporating the heat exchanger.

A tumble dryer having a heat exchanger according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which :- Figure 1 is a perspective view of the heat exchanger, Figure 2 is an enlarged detail view of part of the heat exchanger, Figure 3 is a rear view of the tumble dryer incorporating the heat exchanger of Figure 1, and Figure 4 is a schematic side view of the tumble dryer illustrating the major components of the dryer and the direction of airflow.

Referring to Figures 1 and 2, the heat exchanger comprises a plurality of tubes 1 having a generally rectangular cross-section, adjacent tubes 1 being spaced apart at their ends by outwardly facing channel section members 2 the sides of which are spot-welded to adjacent tubes. The members 2 extend beyond the tubes 1 and the extensions are attached to L-section end plates 3, as best illustrated in Figure 2.

Thus, the tubes 1 provide passageways 10 for air to pass from the front to the rear of the heat exchanger and the spaces 4 between adjacent tubes provide passageways for air to pass from the bottom to top of the heat exchanger, the passageways being isolated one from the other.

The major surface 5 of each tube is preferably in the shape of a trapezium, the angle between adjacent edges 6A, 6B being about 30 . However, the major surface could be a rectangle.

For attachment to the tumble dryer of Figures 3 and 4, the heat exchanger is located in a housing 7 which has an inlet opening 8 attached to the exhaust opening of the tumble dryer, an outlet or exhaust opening 9 for passage of air to atmosphere, and an opening 11 communicating the rear of the heat exchanger with the intake opening of the tumble dryer.

In use, ambient air is drawn by the tumble dryer fan 12 into the front of the heat exchanger through the tubes 1 and the opening 11 to the heating section 13 of the dryer. From there the air passes through the drying drum 14 where it becomes moist and through the exhaust opeing of the tumble dryer. The air then passes into the bottom of the heat exchanger through the spaces 4 to the exhaust 9 and to atmosphere.

Because the air passing from the tumble dryer is moist, some condensation occurs in the heat exchanger and means (not shown) are provided for draining condensate.

The components of the heat exchanger are preferably formed of galvanised steel and are spot welded together where necessary.

In a tumble dryer of 96000 BThU capacity, typical dimensions of the heat exchanger are: Overall depth from front to back - 40 inches Height of each tube 1 - 7 inches Width of each tube - inch Space 4 between adjacent tubes, i.e.

width of the base of each member 21 inch Length of each member 2 - 172 inches Thirty one tubes are provided and are attached to thirty two channel members 2 at the front and thirty two channel members at the back. Thus, when mounted in the housing 7, there are thirty two spaces 4.

All components are made of 26 gauge galvanised steel.

It has been found that the above described configuration and dimensions of the heat exchanger provides an exchange surface area to provide a worthwhile increase in efficiency of the tumble dryer and a consequent saving in fuel costs.

It will be appreciated that the heat exchanger can be readily fitted to either existing or new tumble dryers.

Although described above in a tumble dryer, the heat exchanger could be used in other systems or machines where air is drawn in, heated and discharged to waste and the size and shape of the exchanger can be altered to suit particular systems or machines.

Examples of possible uses of the heat exchanger are in a laundry drying plant and ventilation systems for buildings such as hospitals, office blocks, shopping centres, or industrial premises.

In the use of the heat exchanger it is preferably located at or near a point midway between the inlet for air and the outlet for heated air.

The above-described heat exchanger has the advantage over other appliances previously used that it has no moving parts and the paths of fresh air and exhaust air are isolated from each other. Furthermore the heat exchanger is relatively easy and cheap to manufacture.

Claims

1. A heat exchanger comprising a plurality of elongate tubes of generally rectangular cross-section through which ambient air can pass, said tubes being spaced apart laterally to define therebetween spaces of generally rectangular section through which air from a heating source may pass across the major surfaces of the tubes.

2. A heat exchanger according to claim 1, wherein adjacent tubes are spaced apart by outwardly facing channel-section members, one located at each end of the tubes, which define ends of the spaces between adjacent tubes.

3. A heat exchanger according to claim 1 or 2, wherein the major surface of each tube is generally trapezoidal in shape, the included angle of two sides of the trapezium being preferably 30Q.

4. A heat exchanger according to claim 1 or 2, wherein the major surface of each tube is rectangular in shape.

5. A heat exchanger according to any of claims 1 to 4, wherein the components of the heat exchanger are made of galvanised steel and welded together.

.

6. A heat exchanger constructed and arranged substantially as herein described with reference to the accompanying drawings.

7. A machine incorporating a heat exchanger according to any of the preceding claims.

8. A tumble dryer incorporating a heat exchanger according to any of claims 1 to 6.

9. A tumble dryer constructed and arranged substantially as herein described with reference to the accompanying drawings.