US2602648A

US2602648A - Heat exchange apparatus

Info

Publication number: US2602648A
Application number: US93917A
Authority: US
Inventors: Charles S Martel
Original assignee: Standard Thomson Corp
Current assignee: Standard Thomson Corp
Priority date: 1949-05-18
Filing date: 1949-05-18
Publication date: 1952-07-08
Anticipated expiration: 1969-07-08
Also published as: FR1022330A; GB721870A; GB705571A

Description

July 8, 1952 c s, MARTEL 2,602,648

HEAT EXCHANGE APPARATUS Filed May 18, 1949 2 SHEETS-SHEET 1 INVENTOR. CHARLES S. MARTEt A T TORNEYS J y 1952 c. s. MARTEL 2,602,648

HEAT EXCHANGE APPARATUS Filed May 18, 1949 2 SHEETS-SHEET 2- Fig. 5

INVENTOR. CHARLES S. MARTEL BY Q? ATTORNEYS Patented July 8, 1952 UNI TED EP'ATE N T OF FliClE 2.602.643 :HEA'IiJEXCIlANGE APPARATUS Charles s. 'Martel; JlVIedford; Mass), assignorw .StandardlThomson Cor-poration,;Boston,;Mass.,. 'azcorporatibnzofiDelaware Ahlllibiatibnimaytm, 1949,,Serial No. 93,917

I The ipresentiinvention relates to 'heatexchange "apparatus and more, particularly to li'quid-to-liqcooler 'orp'at leastenables the use of a small size of' such equipment wherebytthe aerodynamic difficulti'es: due to introduction .of air athigh speed may be eliminated or'redu'ced. However the high pressures in both. the .fuel and oil.lines militate against the use of standard forms of heat ex-' :changc apparatus.

The object of the present invention is to provide a simple and readily constructed 'oil' cooler .capable of" efficient heat transfer" between liquid and liquid: andlcapable of withstanding high pressures.

To this end the principal feature of the pres ent invention comprises a cellular construction inwhich the casing is of small cells, each" con- 'stituting 'a single path for the .oil whereby the useiiof' longitudinal bafiie plates isavoided. Each 'CBllTlS. provided with a core of a relatively small bundle of tubes, the tubes being arranged longi- :tudina'lly'in each cell and in a proper association with the parts 'of' the cell toyprovid'e' for passage "of the; fuel through the'tubes.

In the preferred form the fuel is conveyed through the interior of the tubes and'the lubrieating oil is circulated outside. The tubes and the casing are constructed to withstand the high pressures in both the fuel and the oil systems. In its" preferred form" the cells are of extruded aluminum and the tubestare' likewise of aluminum whereby the advantages of ruggedness and light weight typified by the Woods Patent No. 21292;,99'6 are obtained.

Other features of construction'iconsist of 'certain novel features of construction"and'combinationsfand' arrangement of parts hereinafterdescribed andparticularly defined in the claims.

In the accompanying drawings Fig. 1 is an end elevation of the preferred 'form' of wheat exchange apparatus according to the present invention; Fig. 2 is a side elevation; Fig. 3' is a section .on line -3--3 of Fig. 1 showing. the flows of oil and cooling fluid; Fig. 4.13 a perspective viewshowing the extruded sections of the shell; Fig. '5 is an elevation of a: tube bundle 01"iCDl6;

.Eig. 6 is an end elevation of the coresh wn i Fi'g. Fig. 7' is'a detail view' showing the core aluminum. Inview of the di'iiiculty of extruding the entire cooler in one'piece, the extrusion is preferably carried out in sections whereby the two end portions indicated generally at [-4 and it are each-extruded" with three cells, while the 'center'section lfi'has fourcells. The sections 'are'forme'd with welding flanges l9 (Fig. 4) which are welded together as indicatedat 20 (Fig; 1') to form the complete casing. As clearly'shown in the drawing, each cell is formed with bowed or arcuate outer'side walls to withstand internal'pressures.

Received within each cell is a tube bundle indicated at '22. The'bundle formsa core of a relatively small number of tubes. For example, in a construction now in use each core-has at'tubes and the dimensions-ofthe cell are approximately 1 4 inches across by 2 inches from side to side.

Each core comprises two tube sheets 24, 'the tubes 6, and the intermediate bafiles 28 to be referred to later. The tubes are of extruded aluminum, preferably about /4 inch in outside diameter and having a wall thickness somewhat greater than is used in liquid-to-air heat exchangers; preferably the wall thickness is about 0.014 inch. The tube sheets 24 are flat aluminum plates properly punched to receive the tub-es. The'intermediate bafflesZB are arranged to give a sinuous flow to the oil. Hence'each baillec'omprisesa punched section 29 to receive somewhat more than half the tubes and an open section 30"through which't'he' oil may pass in themanner indicated in Fig; 3'. Two baflles 28" maybe used for each bundle, the two baflles being'reversed relatively to each other, wherebythecirculating' oil is forced from'one side of the bundle to the other in a sinuous fashion, so that it contacts all of the tubes without channeling.

A core 22 is inserted into each cell, th-eitube sheets being of the proper shape to conform closely to "the walls of their own cellsyand' the core is positioned therein as shown in Fig. 3. Each core is retained in its corresponding cell by "brazing a'sindicated'at'32; the brazing preferably being carried out accordingflto th'eprocess described in the Woods Patent No: 23893175, dated November'20, 1945'.

Immediately inside the tube sheets the cells are provided with ports 33 communicating with adjacent cells for passage of the oil from cell to cell. The oil is introduced in one end cell at 34 and flows in series through the cells to the outlet 35 in the cell at the opposite end.

Immediately beyond the tube sheets 24 are ports 31 for passage of the heat exchange medium through the tubes and cells. An inlet fitting 40 spans the two cells shown in the upper right portion of Fig. 3, and an outlet fitting 42 spans the two cells shown in the lower left corner of Fig. 3. These fittings are brazed or welded to the casing. The cells may be closed by suitable flanges attached to opposite sides of the heat exchange apparatus, but preferably the cells are individually closed by caps 44 shown in Figs. 3 and 8. Each cap is inserted into the end of its corresponding cell and is suitably brazed or welded into position. If desired the caps may be welded to the cells and this construction is preferable because of the greater resistance to pressure.

In operation, fuel serving as the heat exchange medium is introduced at 40 and removed at 42. The fuel may pass through the tubes of the several cores in succession, but to reduce the pressure requirements, the flow is preferably through a series of parallel pairs of cores. Thus, as shown in Fig. 3 the fuel entering at 40 flows through two tube bundles in parallel and is then directed into the next two bundles, and so on, until the last two bundles discharge it into the outlet 42. The ports 31 are disposed so as to provide for parallel flow through adjacent bundles.

A thermostatic oil flow control valve 45 is secured to a pad 46 welded on the casing adjacent the oil outlet 35. The valve is provided with an oil inlet 48 and an outlet 50. runs from the valve body to the oil inlet opening 34. The oil flow is controlled by a thermostatic device shown in outline at 52 in Fig. 2,'the construction of which may be of any suitable form familiar to those skilled in the art whereby the oil may be directed from the valve inlet 68 through '52 tothe casing inlet 34 and thence around the tubes to the outlet 50, as indicated by the solid arrows in Fig. 2, or may be by-passed from 48 to 50 as indicated by the broken arrow. When the oil is hot, it is circulated through the exchanger, but when its temperature falls below a certain point, it is by-passed from the cooler.

It will be observed that the general flows of liquids are counter-current.

An important feature of the invention is the arrangement to Withstand high pressures. The pressures are relatively high, in some instances being about 1,000 pounds per square inch for the fuel and about 300 pounds per square inch for the oil. The tubes have a sufficient wall thickness to withstand the internal pressure. Furthermore, the system is highly resistant to oil surges without the necessity of using a surgerelief valve as is customary in heat exchangers of the conventional type. The. small cellular construction resists bursting pressures of the casing up to any surge pressures normally encountered. Furthermore, the surges do not afiect the tubes since no crushing pressure is applied to the tubes until the external pressure exceeds the internal pressure. Since surges of more than 1,000 pounds per square inch are not usually encountered, there is no tendency toward crushing of the tubes. The avoidance of the A connection I surge-relief valve is important for reasons of reduced cost and improved reliability.

The arcuate arrangement of Fig. 1 is useful in some designs where the heat exchanger partly surrounds the jet engine or other equipment. Where such an arrangement is not required the cells may be arranged in a straight pattern, either in a single row or in a plurality of rows, as indicated in Fig. 11, wherein an extruded casing 54 is formed with small cells 56 having pressure-resisting curved outer walls 58, and internal partitions, shown as straight longitudinal walls 60 and transverse walls 52. The tube bundles or cores may be mounted as shown at 64. No flow. diagrams are given in Fig. 11, and the particular arrangements of the parts, fittings, closures, etc. are not shown, since they will, in general, be similar to those previously described.

Although the invention has been described as embodied in an oil-to-fuel heat exchanger for aircraft, it'is not limited to such service but may be appliedto any liquid-to-liquid exchanger, especially for operation at high pressures.

Having thus described my invention, I claim:

1. A liquid-to-liquid heat exchanger for operation at high liquid pressures comprising an extruded shell having a plurality of small tubular cells, each cell having a generally cylindrical exterior surface, the shell having unitary'partitions separating adjacent cells, a core for each cell comprising a bundle of straight tubes, each core having tube sheets at opposite ends, each tube sheet being of the same shape as the crosssection of its corresponding shell, means for sealing the tube sheets into the cells, inlet and outlet members connected to direct one liquid through the tubes, the partitions having ports outside the tube sheets on opposite sides to direct said liquid through the tubes and having ports between the tube sheets on opposite sides of adjacent cells to direct the other liquid in a series of longitudinal passes around the tubes in the several cells, and closures for the ends of the cells.

2. A liquid-to-liquid heat exchanger for operation at high liquid pressures comprising an extruded shell having a plurality of small tubular cells, each cell having a generally cylindrical exterior surface, the shell having unitary partitions separating adjacent cells, a core for each cell comprising a bundle of straight tubes, each core having tube sheets at opposite ends, each tube sheet being of the same shape as the crosssection .of its corresponding shell, means for sealing the tube sheets into the cells, inlet and outlet members connected to direct one liquid through the tubes, the partitions having ports outside the tube sheets on opposite sides to direct said liquid through the tubes and havingports between the tube sheets on opposite sides of adjacent cells to direct the other liquid in a series of longitudinal passes around the tubes in the several cells, baille members mounted on each bundle and having open portions extending partially across the tube space to impart a sinuous path to said other liquid, and closures for the ends of the cells.

3. A liquid-to-liquid heat exchanger for operation at high liquid pressures comprising an extruded shell having a plurality of small tubular cells, each cell having a generally cylindrical exterior surface, the shell having unitary partitions separating adjacent cells, a core for each cell comprising a bundle of straight tubes, each core having tube sheets at opposite ends, each tube sheet being of the same shape as the crosssection of its corresponding shell, means for sealing the tube sheets into the cells, inlet and outlet members connected to direct one liquid through the tubes, the partitions having ports outside the tube sheets on opposite sides to direct said liquid through the tubes and having ports between the tube sheets on opposite sides of adjacent cells to direct the other liquid in a series of longitudinal passes around the tubes in the several cells, and individual closures welded into the cells at the ends thereof.

4. A heat exchanger as defined in claim 1 wherein the cells are arranged in a single arcuate row on an arc of large radius.

5. A heat exchanger as defined in claim 1 having a plurality of extruded sections each section having a plurality of cells and provided with a welding flange, the sections being welded together,

6. A heat exchanger as defined in claim 1 in which the several cells are arranged in a plurality of rows with longitudinal and transverse internal dividing walls.

CHARLES S. MARTEL.

REFERENCES CITED The following references are of record in the file of this patent:

V UNITED STATES PATENTS Number