US1989996A - Heat exchange unit - Google Patents

Description

Peb. 5, 1935. R. MAUTSCH 1,989,996

I HEAT EXCHANGE UNIT Filed Jan. 5, 1952 y 'lll/I Patented Feb. 5, 1935 UNITED STATES- remates PATE NT` OFFICE HEAT EXCHANGE UNIT Robert Maatsch, Brussels, Belgium, assigner tg Manufacture Generale Metallurgique, Societe Anonyme, Brussels, Belgium, a company of Belgium Application Jan s, 1932, serial? No. 584,866

In Belgium February 26, 1931 5 Claims. (01.'25'1-248) made of cast iron or of an alloy of aluminium,

for example, Whilst the tubes are of copper or other metal having a low resistance to the iiow of heat and good `anticorroding properties, but

` being unsuitable for casting or of prohibitive cost.

For many purposes it would however be desirable l that the headers, or at least those portions thereof which come into contact with the iiuid. flowing through the apparatus, be made of the same metal as the tubes, or of some metal possessing properties considered requisite for the eiiicient operation of the apparatus.v By this means it would be po'ssible to obviate oxidization or corrosion of the f headers and the effect thereof upon the 'uid flow'- ing-through the heat-exchange apparatus, as well as to preclude certain electrolyticaL phenomena liable to cause serious damage, due to theformation of electric cells at the points where tubes and headers consisting of different metals are joined together, and to the presence of a liquid in thel apparatus.

The present invention supplies simple means for attaining this end without increasing the cost ofthe heat exchange units appreciably, by providing a header-box whereof the walls consist'of thin sheets of the metahselected for use', said headerbox being strengthened by means of a metallic outer jacket or casing which may be continuous and enclose -the sheet metal header-box completely, or be formed to enclose only certain portions of the same, the joints for example, the remainder of the-header-box being left bareif it is Inot intended to withstand high pressures. Preferably, the header box itself is u sed as a casting core, and the metal of the j acket or casing is cast directly around the same.

Many known means are available, such as threaded nipples, soldering, welding, expanding .and the like, for securing tubes to headers. It is voften difhcult however to obtain by any of these l means joints adapted to remain iiuidtight at high pressures and, according to the invention', the ends 'of said tubes are therefore preferably exp,-

' iron casing.'

bedded in and rendered integral with the metal of the casing surrounding .the header, when' said ca sing is cast. For this purpose, the tubes are joined tothe header-box, said header-box is `placed in the casting mould to act as a casting -core therein, and metal is then cast into said mould around the ends of the tubes at the same time asv it is cast around the header-box or those portions thereof which it is desired tovstrengthen. 4The tube-ends anchored within the header-box may be smooth, may be provided with a ring shrunk thereon, or may be corrugated and beA provided with said shrunkring or not, butlthey are preferably strengthened to withstand the" v shrinkage stressesof the metal cast to form the casing, by being provided with an inner liner. Said tube ends are preferably fitted into openings inthe header-box previous to casting, and

plain or threaded nipples fitted into openings -in the header-box in the like manner likewise become embedded in the metal, when the same is cast to form a casing or jacket.

In order that the invention may be clearly understood and readily carried into effect, the same will nowbe described more fully with reference to the accompanying drawing which il1ustrates,'by way of example, a few constructional embodiments thereof and -in which:

liig. 1 is a horizontal section of a header-box and of the separate members to be assembled therewith, before casting, A

. Fig. 2 shows, likewise in horizontal section, the' same members assembled with the header-box and embedded,v together Figs. 3 to 6 show modifications of the invention. In all of the figures, 1 indicates the thin metallic header-box, to which the tubes 2 of the heat ex- 'change apparatus are secured by expansion or' by other suitable means, and 3' indicates themetal casing cast around said header-box 1 which is used as a casting core, and around the ends vof tubes 2. An internally threaded nipple 4, expanded or otherwise secured in header-box 1, is likewise embedded in the metal of casing 3 by the casting thereof.

In the constructional embodiment shown in Fig, 2, the ends of tubes 2'are smooth, devoid of vany reinforcement, andare gripped in the metal of casing 3 solely by the pressure of said metal due to lthe shrinkage thereof after casting. When said tubes are thin, as is usually the case, their ends are preferably reinforced by means of an inner liner 5 (Fig. 3) adapted to prevent the collapse ofthe side wall of said tubes under the with the same, in a cast f pressure set up by the shrinkage of the cast metal, and thus to assist in providing a solid' The strength of anchorage for the tube ends. said anchorage may further be enhanced by shrinking upon the tube ends a ring of comparatively large diameter 6 (Fig. 4,) adapted to resist still better the shrinkage stresses of 'casting 3 and to provide a joint'the tightness of, which is all the greater that said stresses act upon' a large diameter. Should the metal of said casing not l surround the tube in a perfectly iluidtight manner and some of the fluid 'contained inthe header therefore coze along tube 2,'ring6 will force said uid to follow a path so circuitous esito -be alone suiiicient, in most cases, to arrest said oozing.

Instead of being smooth, the end of tube 2 may be ..roughened, threaded or corrugated as at *I (Fig. 5), to afford the cast metal of the casing a better grip upon said tube and likewise to 'force any fluid oozing along lsaid tube to travel a cir--l cuitous path.

The greatest possible degree of resistance to mechanical stresses and a joint adapted to remain tight irrespective of the pressure of the fluid within the header and tube, may be obtained by providing within the corrugated tube end a smooth or corrugated strengthening-liner 5a (Fig. 6), and by shrinking an outer ring 6a upon said tube end between two of said corrugations 7.

reinforced or made tight. This modiiication may be met, according to circumstances, by a suitable arrangement of the mould.

The invention is not however limited to the use of a cast jacket or casing and in certaincases this member may, be formed merely of a Jacket me chanically cold fitted or hot shrunk around header-box 1, tubes 2'and nipples 4 being then assembled with said header-box in a'uid tight manner, by being expanded or soldered therein, for example. Neither is the invention restricted to any of the further constructional details hereinbefore described, which might be modied Widely without departure from its scope, said invention beingv limited'only by its essential features as set forth Yin the appended claims.

I claim: 1. In a heat exchange unit, the combination of an apertured header member formed `of sheet metal of high thermal conductivity, with a plurality of tubes having lateral projections. formed at the ends thereof, said tubes being formed of a j metal analogous to that of said header member and being each secured by one end in one of said apertures, a pressure resisting liner within each said Atube end, and an outer stress-resisting casing of cast metal around said header member and said tube ends, and rigidly gripping said projections on said tube ends.

2. In combination in a heat exchange unit, anapertured header 'member formed of sheet metal, a plurality of tubes each secured by one end within said header member through one of said apertures. a connection nipple secured within said header member through one'l of said apertures, a ring of comparatively large ,diameter shrunk outwardly upon each of said tube ends' and a casing of cast metal extending'around in immediate contact with said header member,

- tube ends, shrunk rings 'and conne'ction nipple,

to hold the same in uidtight relationship -for the purpose setl forth. Y

.3. In combination in a heat exchange unit, an

apertured header member formed of-heat con-` l ducting sheet metal, a plurality of' tubes formed of an analogous metal and each anchored by one end within said header member through one of said apertures, a threaded connection nipple anchored within :saidheader member through another of said apertures, a pressure-resisting liner-inserted in each said tube end, lateral projections upon each said tube end 'formed outward- .ly'of the periphery thereof, a ring'` of comparatively large diameter shrunkupon said lateral projections of said tube ends, and a metal casting formed in contact with and around said assembled header member, tube-ends, nipple, liners, projections and rings and enclosing and gripping the same.

4. In combination in a heat exchange unit, an aperturedhhead'er member formed of thin heatconducting metal, a plurality of tubes formed Vof a cognate-metal and each secured by one end within, said header member through one of said apertures, a threaded connection nipple secured within said header member through another of said apertures, a stiifening liner'within each said tube end, lateral projections formed outwardly of said tube ends, a large-diameter ring shrunkoutwardly upon each said tube end, and a metal jacket fashioned and secured around and in contact with said header member, tube ends, nipple,

projections and rings, said jacket enclosing and gripping the same in fluidtight relationship.v

5. A jointed, two-part heat exchange device. consisting of means for the almost instantaneous exchange of heat between the device and the-fluid to be acted upon while avoiding electrolytic action at the joint between the said two-parts and the occurrence of detrimental oxides, at the same time imparting sumcient strength to the device to withstand the high mechanical vstresses normally encountered in heat exchange use while enabling th'e maintenance of first-cost at a; minimum, the said means comprising a complete boxshaped header member, comprising one of the said two-parts, formed of Athin sheet metal of high thermal conductivity, said header being too weak in itself to withstand the stresses prevailing when it is in operation, said header member having apertures therein. a plurality of tubes 'capable of directly contacting with and entering into intimate heat .exchange relation with the iluid to be acted upon. and formedpof the same metal as the header, and comprising the other of the said two parts, jointed to the first part, said tubes being sufliciently thinto enter into almostinstantaneous-heat exchange with said fluid, said tubes each having -oneend 'engaged in an aperturebf said header member, and an 'l outer casing strong enough tov resist the mechanical stresses which prevail, and formed oi an inexpensive metal'cast in substantially iiuidtight manner about only the ends of. said'tubes and about the ioint between the ends of the tubes andthe Aadjacent poi-tions of said sheet metal header member, and at least partly surrounding the-remaining portions of said header member, said tubes projecting outwardly'from said-casing.

. ROBERT MAUTSCH.

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