US2539669A - Sectional heat exchanger - Google Patents

Description

Jan. 30, 1951 wo r 2,539,669

SECTIONAL HEAT EXCHANGER Filed May 4, 1946 2 Sheets-Sheet l INVENTORS MARTIN NEWCOMER BYCOLEMAN 5. WILLIAMS am/awfllmv GUM ATTORNEYS 1951 M. NEWCOMER ETAL SECTIONAL HEAT EXCHANGER 2 Sheets-Sheet 2 Filed May 4. 1946 lllll ill. llrlrl'az 4 I l l l ll INVENTORS MART/N NEWCOMER COLEMAN 5v W/LL/AMS M, WM*MM Patented Jan. 30, 1951 SECTIONAL HEAT EXCHANGER Martin Newcomer, Branford, and Coleman 5. wuliams, Sangatuck, Conn., assignors to Olin Industries, Inc., New Haven, Conn., a corporation of Delaware Application May 4, 1946, Serial No. 667,380

2 Claims. 1

These heat exchangers interpose no excessive.

resistance to flow of hot oil but often interpose excessive resistance to the flow of thick cold oil. Various expedients have heretofore been proposed to overcome this condition, including the provision of a. valve-controlled bypass for the thick oil in the form of an annular conduit, sometimes referred to as a muff, surrounding the heat exchanger. As the oil warms, its passage through the muff heats the congealed oil in the heat exchanger, which operates the valve control to transfer oil flow from the muff back to the heat exchanger proper. commonly made in the form of a single unit divided into sections by bafiies to give the necessary tortuous path of oil flow. The aboven'ientioned features in prior oil coolers give rise to certain structural and operational disadvantages such as lack of suflicient strength, lack of flexibil ty to meet space demands, difllculty in assembling. difficulty in controlling air turbulence.

The present invention overcomes these disadvantages by providing a plurality of separate but smaller units without baffles; by providing special connections to constrain the hot thin oil to flow through the several units in series while permitting the cold congealed oil to flow through the units in parallel, thus greatly reducing resistance to flow of cold oil: by providing manifolds to connect and properly align and space the several units, and to contain the relief valves to control automatically changeover between series and parallel flow.

The invention also consists in certain new and original features and combinations hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part hereof, in which:

Fig. 1 represents somewhat diagrammatically a perspective of a sectional heat exchanger according to the invention;

Fig. 2 is a perspective of the separate units with the manifolds disconnected;

Such oil coolers are also Fig. 3 illustrates, partly diagrammatically, the construction of the manifolds and their relation to the heat exchanger units and also indicates by arrows the normal series path of hot thin oil through the exchanger; and

Fig. 4 is a view similar to Fig. 3 but showing by arrows the parallel paths through the heat exchanger of cold, thick oil.

In the following description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

In the drawings accompanying and forming part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspect of the invention.

Referring now to the drawings, the heat exchanger as illustrated comprises, in general three I seetion w; M. and i2 substantially identical and connected together with their air paths substantially in line. Connecting the several sections are two manifolds l3 and It with springpressed relief valves within (see Figs. 3 and 4) for determining whether the oil passes through the several sections in series or in parallel. The hot oil, which is relatively thin, passes through the sections in series, as indicated by the arrows in Fig. 3, while the cold oil, which is relatively thick, passes through the sections in parallel, as indicated by the arrows in Fig. 4.

Since the heat exchange sections or units III, II and I2 are substantially identical, it is srfilcient to describe only one in detail. Section III comprises a stack of tubes I5 nested to form core IS. The tubes are generally cylindrical with their ends hexed and enlarged, the ends being soldered or otherwise secured together to form built-up headers at each end of the core, one of which headers is indicated by l l. The air passes lengthwise through the tubes while the oil passes into the spaces l9 between the tubes transversely of their lengths. The section has a circular cylindrical shell 20 with end caps or collars 23 connecting the built-up headers H. The shell 20 has diametrically opposed openings 22 to which pads 2| are connected by soldering or otherwise.

The sections l0, H and I2 are disposed with their tubes substantially in line and their respective pads 2| substantially in line but with ad- Jacent headers spaced as indicated, particularly the stud holes 28' in the pads 2| being indicated in Fig. 2.

For supporting the intake manifold relief valve in proper position, a valve sleeve 30 is provided, this sleeve having a plug 3| screw threaded into the lower end of main tube 26. The valve sleeve 33 has a valve seat 32 threaded thereto slidably receiving a spring pressed valve disc 33 normally held closed by spring 34 operating between seat 32 and an abutment on the valve stem 36. The valve sleeve 30 has portions 35 of reduced diameter located opposite the branch pipes to sections II and 12 so as to provide communication between the interior of the valve sleeve and the several units, regardless of the rotary position the valve sleeve 30 assumes when it is screwed home.

The outlet manifold i4 comprises a main tube with branch tubes 4| connected to their respective pads 2|. The lower end of main tube 40 has outlet pipe 42 secured thereto for leading the cooled oil to the desired point. Within main tube 40 is valve sleeve 43 threaded into position by plug 44. Valve sleeve 43 carries a removable seat 45 slidably supporting a valve disc 46 nor-.

mally held closed by a spring 41 operating between the valve seat 45 and a suitable abutment on valve stem 49. The valve sleeve 43 has portions 48 of reduced diameter opposite the connecting tubes to sections l0 and H for the purpose of insuring communication between these sections and the inside of the valve sleeve 43 regardless of the particular rotary position which the valve sleeve may take as the plug 46 is screwed home.

The spaces 24 between the shells 20 of the several sections are closed by seals comprising rubber bands 52 surrounded by metal clamping bands 5| having conventional apertured ears which may be drawn together by bolts indicated by 53. These bands 5|, 52 operate merely to close the air path extending through the tubes of the several sections. If desired, special bands, indicated by 54 and 55, may be provided on the top and bottom of the assembly for connection ,to suitable ducts (not shown) which may be provided for bringing cooling air to the exchanger and leading it away.

The operation of the exchanger will be apparent from consideration of Figs. 3 and 4. The oil to be cooled issupplied by pipe 29 andled away from the heat exchanger by pipe 42. Air passes through ,the tubes upwardly in the figures from the bottom to the top, thus providing the advantages of counter-current flow of air and 011.

Fig. 3 indicates the normal flow of oil when it is warm and free flowing. Here the resistance interposed by the relatively thin oil is insumcient to build up enough pressure to open the relief valves 33 and 46. Thus here the oil flows from supply pipe 29 serially through the several units, as indicated by the arrows in Fig. 3. and out discharge pipe 42.

If the oil is cold, a situation which may occur. for example. when cooling aircraft engine oil, it

may be comparatively thick having, under some circumstances, the consistency of Vaseline. Under these circumstances the series path through the exchanger offers such high impedance to oil flow that the oil pump (not shown), supplying the oil to inlet pipe 23, ma build up considerable pressure. This will open inlet manifold valve 33 supplying pressur directly to the several sections by way of manifold l3. Similarly, the higher pressure being transmitted through the several units will open outlet manifold valve 43. This valve operation causes the oil flow through the exchanger to be as indicated in Fig. 4.

Thus the heat exchanger becomes in effect a parallel flow type whose combined resistance is substantially one-third of the resistance of any single unit taken alone; this compares with a resistance of three times that of a single unit which is obtained with the units in series. Thus the overall resistance of the heat exchanger with parallel flow may be of the order of one-ninth of the resistance of series flow, assuming of course oil of equal temperature.

As the oil temperature rises, the oil thins and the back pressure due to resistance of the units drops, thus permitting the relief valves 33 and 46 to close, thus automatically changing back to series flow as indicated in Fig. 3.

It will be noted that the tubes is of the several sections l0, II and I2 are substantially in line or in register if all parts are accurately made. Under certain conditions, particularly in aircraft use, it is sometimes desired to change the turbulence flow of the air passing through the heat exchanger tubes for difierent air speeds. The present construction lends itself very easily to positive and deliberate disalignment of the several sections to bring the tubes of the several sections slightly out of register and thereby change air turbulence characteristics. This may be done by placing shims of diiTerent sizes between the pads 2| and the connecting tubes 2? of the several manifolds so as to shift slightly the central axes of the several drum shaped units with respect to the manifolds. For example, it may be sufiicient to shift the middle section ii slightly with respect to upper section it and lower section l2. Another manner of obtaining difierent air turbulence characteristics is to rotate the middle section II, for example, with respect to sections HI and [2 about the main axis thereof so as to bring the tubes out of register. This may be done by shifting the pads 2i on the middle section II slightly in a circumferential direction before they are welded or soldered onto the shells 20.

It will be understood that the several drum shaped sections may be held together in ways other than shown and that the series-parallel control of oil flow may be obtained in ways other than shown. For example, the several units may be placed end to end in a single cylindrical shell and tightly secured in position, with appropriate conduit connections and valves to provide the desired series-parallel action.

It will be understood that the heat exchanger and the matrix of heat transfer parts thereof may be made of any suitable heat-conducting material, copper or aluminum being given by way of example. Also the heat may be exchanged between fluids other than oil and air, these two fluids being given merely for purposes of illustration. Flu'thermore, the number of sections or units may be varied as well as their size and proportions. Also, instead of using cartridge type units where the enlarged ends of the tubes make up the headers, other types of heat exchange units may be used, as for example, the type where the tubes are secured to plateheaders.

Numerous advantages follow from the features of this invention. The use of a plurality of separate sections makes possible the use of shorter tubes. Shorter tubes have the advantage of being manufactured with less scrapping. The shorter section or shell withstands greater internal oil pressure by reducing barrel bulging.

The several sections being substantially alike and being small, a defective section is easily and less expensively replaced. For example, in case of engine failure, babbitt from the bearings, which may get into the oil stream, very often lodges in the first section. Under such condition, this section can easily be removed and replaced by a new section.

A further advantage of use of multiple smaller sections is the elimination of baflles which are often necessary when a single large unit is used. Baiiies are particularly troublesome when assembling a heat exchanger, particularly of the type where the tubes must be threaded through numerous headers and baflle plates.

The separate manifolds provide advantageous mounting for the relief valves,'serviceable conduit connection between the several units and also positively holds the several units in proper assembled relationship.

The use of the series-parallel flow shift eliminates the need for the bypass muff. The thick oil flows in parallel through the heat exchanger back to the engine where it is heated to increase its fluidity so that normal series operation can be obtained.

The spacing between the adjacent headers of the several units assists in providing air turbulence and the adjustment of the several units permits easy adjustment of this turbulence.

While certain novel features of the invention havev been disclosed herein, and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. In a sectional heat exchanger, a stack of separate units, each unit comprising an outer container having a first opening and a second opening, a matrix of heat exchange walls within said container, said matrix providing a passage for a first fluid from one opening to the other, said matrix also providing a second passage for a second fluid in heat exchange relation to said first fluid; a conduit system comprising a main supply conduit, a main discharge conduit, and connecting conduits connecting said discharge and supply conduits with the openings of the several units to direct the flow of said first fluid from said supply conduit through said units in series to said discharge conduit; means operated by increased pressure due to increased viscosity of said first fluid for changing the aforementioned series flow path of said first fluid to a parallel flow path, said parallel path leading from said sup ply conduit through said units in parallel to said discharge conduit, said units being arranged so that said second fluid passes through said units in series,whereby counter-current flow of said first and second fluids may be obtained when said first fluid is flowing through said units in series.

2. In a sectional heat exchanger for use as an oil inter-cooler with internal combustion engines and for like uses, said heat exchanger being subject to a flow of oil whose viscosity varies, a stack of at least three separate units; each unit comprising a series of tubes extending generally parallel to the main axis of the stack. headers connecting the ends of the tubes, a shell surrounding the tubes and connected to said headers. each said unit having a first opening and a second opening to pass oil through said shell around the outside of said tubes; the adjacent headers of adjacent units being disposed in close proximity so that air may pass through the tubes of the several units in series; a conduit system comprising a main supply conduit, a main discharge conduit, and connecting conduits connecting said discharge and supply conduits with the openings of the several units to direct the flow of said oil from said supply conduit through said units in series to said discharge conduit; spring means operated by increased pressure due to increased viscosity of said oil for changing the aforementioned series flow path of -said oil to a parallel flow path, said parallel path leading from said supply conduit through said units in parallel to said discharge conduit, whereby counter-current flow of oil and air may be obtained when said oil is flowing through said units in series.

MARTIN NEWCOMER. COLEMAN S. WILLIAMS.

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

UNITED STATES PATENTS Number Name Date 1,425,674v Monaghan Aug. 15, 1922 1,778,810 Nichols Oct. 21, 1930 1,944,992 Miller Jan. 30, 1934 2,323,994 Hiit July 13, 1943 2,327,491 Blais Aug. 24, 1943 2,352,704 Garner July 4, 1944 FOREIGN PATENTS Number Country Date 391,556 Great Britain May 4, 1933 480,047 Great Britain Jan. 20, 1937

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