Heat exchanger

Abstract

A heat exchanger and a method for manufacturing a heat exchanger, the heat exchanger comprising: a first plurality of layers, each of the first plurality of layers including: a corrugated sheet comprising a series of regular corrugations across its width for flow of liquid therethrough, the series of corrugations having a predetermined period; and a de-congealing channel for flow of liquid across the width of the corrugated sheet in parallel with the corrugations, the de-congealing channel formed at least in part by two adjacent corrugations, that are separated by greater than the predetermined period.

Claims

1. A method of manufacturing a heat exchanger, comprising: forming a layer of the heat exchanger, forming including: stamping a series of regular corrugations with a predetermined period into a metal sheet to form a corrugated sheet; and skipping a corrugation stamping step so as to create a space between two adjacent corrugations in the corrugated sheet which are thus separated by greater than the predetermined period, and thereby create at least a part of a de-congealing channel.

2. The method as claimed in claim 1, further comprising repeating the step of forming a layer so as to form a first plurality of layers for a flow of oil therethrough, providing a second plurality of layers for a flow of fluid therethrough, and forming the heat exchanger by alternating layers of the first and second pluralities of layers so that in use oil in the first plurality of layers is in a heat exchanging relationship with fluid in the second plurality of layers.

3. The method as claimed in claim 2, wherein forming the heat exchanger comprises providing intervening separators between the layers of the first plurality of layers.

4. The method as claimed in claim 1, wherein the step of forming a layer of the heat exchanger by stamping the metal sheet comprises stamping the sheet in a first upward direction and in a second downward direction so as to form the corrugations.

5. The method of claim 1, wherein each corrugation has an oscillating geometry along a length of the corrugation across a width of the corrugated sheet.

6. The method of claim 1, wherein each corrugation comprises an opening for fluid communication between the corrugations.

7. The method of claim 1, wherein the de-congealing channel is formed between two of the first plurality of layers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred embodiment of the invention is described below by way of example only and with reference to the accompanying drawings in which:

(2) FIG. 1 shows a perspective view of a layer of a heat exchanger, the layer comprising a plurality of corrugations and de-congealing channel;

(3) FIG. 2 shows a profile view of a portion of the layer of FIG. 1;

(4) FIG. 3 shows plan view of a portion of the layer of FIG. 1; and

(5) FIG. 4 shows a schematic of a heat exchanger comprising layers.

DETAILED DESCRIPTION

(6) FIG. 1 shows a layer 100 of a heat exchanger comprising corrugations 110 and a de-congealing channel 120. The corrugations 110 each extend across the width 170 of the layer 100 and comprise a discontinuous oscillating shape across their length. The length of each corrugation is thus the same as the width 170 of the layer 100. The de-congealing channel 120 is defined between two corrugations 110 and also extends across the width 170 of the layer 100.

(7) FIG. 2 shows the layer 100, corrugations 110, and de-congealing channel 120 in more detail. Each corrugation comprises fins 112 forming side walls of the corrugations. Each corrugation also comprises openings 114 between left and right oscillation portions of the corrugation 110, so that the fins 112 are formed from the side walls of the corrugations 110 by the openings 114. The shape of the side walls of the corrugations 110 are therefore discontinuous, and during use oil may flow through the corrugations 110 and around the fins 112 though openings 114. Oil may therefore also flow between corrugations 110.

(8) The de-congealing channel 120 provides a larger throughway indicated by the boxed outline in FIG. 2. This throughway provides a less obstructed passage for oil flow than do the corrugations 110 with their fins 112. It is therefore easier for congealed or viscous oil to flow through the de-congealing channel 120. The de-congealing channel 120 provides a low-resistance flow path for warm oil to spread heat across to the width 170 of the layer 100.

(9) The corrugations 110 have the form of a square-wave and have a predetermined period 190 in the length direction of the layer 100 after which they repeat. It can be seen from FIG. 2 that the corrugations 110a and 110b immediately to either side of the de-congealing channel 120 are separated by a distance greater than the predetermined period 190. Troughs of each of the corrugations 110a and 110b are adjacent the de-congealing channel 120 on either side thereof.

(10) The layer 100 shown in FIG. 2 is formed by stamping an aluminium sheet both in an upward direction and a downward direction (in the frame of reference of FIG. 2) to form the corrugations 110. Therefore, the de-congealing channel 120 shown has a middle portion 122 which is located approximately half-way up the layer 100. It will be appreciate that this middle portion may instead be located at a different height in the de-congealing channel 120 as necessary, and may be determined by the manufacturing process of the layer. For example, the middle portion 122 may be located at the bottom on the layer, and may thus provide a larger throughway.

(11) FIG. 3 shows how the corrugations 110 oscillate along their length across the width 170 of the layer 100. The lines indicate the edges of the corrugations. It can be seen that some portions of each corrugation 110 are more to the left within the layer 100, and some portions are more to the right within the layer 100. Thus, an oscillating waveform is produced along the length of the corrugation, with the waveform being a square wave in this example. Together with the openings 114 (not shown, but formed in the horizontal line sections of FIG. 3), this geometry provides the fins 112 for interrupting and intercepting the flow of oil across the width 170 of the layer 100 and increasing heat transfer to/from the oil.

(12) If can also be seen from FIG. 3 that the de-congealing channel 120 provides an unobstructed flow path across the layer 100 (shown by the dotted arrow). Thus, oil can flow across the layer 100 through the de-congealing channel 120 more easily than it can flow through the corrugations. More viscous or congealed oil can therefore flow more easily through the de-congealing channel. Hence the de-congealing channel can more efficiently transport warm oil, and therefore heat, across the layer 100 to de-congeal oil throughout the rest of the layer.

(13) A heat exchanger may be formed by stacking the layer 100 with other similar layers, together with layers 200 for another fluid interspersed with the oil-carrying layers. The de-congealing channel 120 in each layer 100 may be aligned so that they are arranged one above the other, or may be arranged at any position along the length 160 of the layer 100 as required, which position may be different for each layer 100.

(14) FIG. 4 shows a schematic of a heat exchanger comprising stacked layers. The oil-carrying layers 100 are disposed either side of layer 200 for another fluid, so that the oil in layers 100 is in heat exchange relationship with the fluid in layer 200. Separators 300 are disposed between the layers 100 and 200. Details of the corrugations 110 and de-congealing channels 120 of layer 100 are not shown in FIG. 4.

(15) The proposed heat exchanger provides increased flexibility of heat exchanger manufacture since a de-congealing channel may be simply provided at any position within each layer. This also avoids the need to manufacture a specialist, dedicated de-congealing layer so provides a simpler manufacturing option. It also reduces the risk of mistakes during manufacture, since the layers may not need to be assembled in a particular order. The de-congealing channel can be used in any heat exchanger configuration/type, and unlike a dedicated de-congealing layer, is not limited to use in multi-pass heat exchangers. The proposed arrangement also offers greater flexibility when it comes to the number of de-congealing channels which can be employed in each unit. The number, and spacing between layers, can be bespoke to fit the demands of each application.