US2142679A - Heat exchanger - Google Patents

Description

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UNITED sfrliTl-:s

PATENT oFFlci:

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Apponon AW 22, 1938,- Bcrial No. 75,689 In Sweden In 9. 1935 This invention relates to heat exchangers, and more particularly to heat exchangershaving heat transmission walls of sheet metal bent to spiral shape to form convolute channels for iluids which exchange heat.

Due to the particular structure of such heat exchangers dimculties have arisen in providing them with suitable end closures. Thus-closure bands rolled into the spiral ends o the channels E@ cannot suitably be removed. Closures consisting of covers and paokings are not reliable, partly as they do not render full security against leakage. and partly as they are dimcult to apply to the apparatus. Moreover, closures oi both these EES kinds are expensive. Particularly they increase considerably the costs oi manufacture of small heat exchangers of the type referred to.

It is an object of my invention to provide a, clo sure in apparatus of the kind referred to which closure is particularly inexpensive in manufacture and ensures complete tightness.

Another object oi my invention is to provide an apparatus ci the sind referred to having closures at the spiral ends of its channels which are easily removable and nevertheless as resistant and tight as any hitherto lmown closure for the saine pur-l pose.

My invention has further for its obiect to materially reduce the entire cost of manufacture of comparatively 'small apparatus of the mnd reierred to by reducing* the cost oi their closure which cost is, tor small apparatus, a disproportionally large part of the entire cost of manufacture.

Still another object oi my invention is to provide a closure for apparatus oi the mnd referred to which clure is quite as resistant and tight es weldedioints but much more easy and inexpensive to arrange and the arrangement of the cloi@ sure will not cause any injurious deformation oi the convolute walls of the apparatus.

With these and other objects not speclcally mentioned in view, the invention compris the provision of certainconstructions and` amanecments hereinafter fully described and then speciiically set forth in the claims hereunto appended.

In the drawingz w Fig. 1 is a cross sectional view taken on the line I--I of Fig. 2 of an apparatus embodying the invention;

We. 2 is a view, partly in section, on the line II-I of F18. l; and et Fig. 3 is a sectional view, similar to Fig. 2, illus- 4 emma (ci. :s1-usi trating part of a modied embodiment `of the invention. i

Referring now to the drawing. the apparatus has two heat transmission walls I and 2 of sheet metal, which are bent to spiral shape, so that two 5 parallel convolute channels 3 and l for heat exchanging iiuid are formed. A fluid to be heated is introduced intothe channel 3 through the inlet connection 8 and discharged through the outlet connection 6 while the heating iluid is introduced 10 into the channel 4 through the connection 1 andl discharged through the connection 5. The convolute -body of the apparatus is formed by rolling up plates of copper, iron or steel to convolute shape and inserting distance pieces Il or bands 16 into the convolute channels to stay and hold apart the convolute walls thus obtained; Thereby a convolute shaped body will be obtained which is open at both of its face ends. The connection pipes 5 and are secured to plates i8 and ita, an respectively, which are secured in fluid-tight relation to the portion of the convolute wall bounding the central space of the heat exchanger. The space between Walls it and lila is divided by means of a fluid-tight partition i9 into an inlet gg chamber 2t and an outlet chamber 2|. The inlet 8 communicates through the chamber 2t and an opening l2 in the wall t with the channel 3, and

the channel t communicates through the chamber 52| with the outlet t. The channel t is closed so with respect to the chamber 2t by means of a wall 23 which extends from the partition it to the bottom of the convolute, while a wall 2t, which. extends from the upper plate it to the upper end of the convolute, closes the channel 4 with respect i5 to the space formed above plate i8. The ends of the convolute shaped body are covered with covers 9 which are cast or machined to form an interior annular rim lil and an outer annular rim il between which rims is obtained an annular cavity mi i2 which may be some millimeters in depth. The inner diameter oi the rim il isslightly greater than the width o the convolute wall body. The covers 9 have central holes i3 for-the connections 5 and l. The spiral ends of the channels 3 and l 41,5 are illled with a fusible metal I4 such as tin. or other metal having a point of fusion below that of the coverst and walls i and 2.

This closure is formed by filling the annular cavity i2 with a metal (possibly pulverous metal) so which is then fused conveniently by heating the cover 9. Then one end of the convolute shapedv body is inserted into the metal bath and the cover 9 and convolute body are cooled, so that the fused metal will solidify and form a rigid and tight joint c6 able rings of wood, for instance, replacing the integral rims l and ll.

This closure can be easily removed by .heating the cover with a blow torch, for instance,- so that the closure metal lll is fused again and then the fluid channels can easily be cleaned Aand inspecty ed.` whereafterthe convolute body is again placed into the metal bath which is cooled and solidied. As the removal and applying of this closure is effected by simultaneous heating over the entire length of the convolute Walls the latter will not be subjected to any local heat stresses and, consequently, there will not arise any undue deformations of the convolutions.

As shown in Fig. 3 the easily fusible closure Ametal can form a cover i5, i. e. part of the cover is fused into the spiral ends of the channels 3 and d between the Wall edges. In such cases there is used a separate casting-mould I5. After the closure metal has solidled the castingmould is removed `and in case the closure metal is to be fused down again the casting-mould is applied to the apparatus as shown in Fig. 3.

While E have shown two more or less specific embodiments of my invention, it is to be understood that this has been done for purposes of illustration only and'in no manner limits my invention, the scope ci which is to be determined by the appended claims viewed in the light of the prior art.

I claim:-

1. In a heat exchanger having heat transmission walls of sheet metal having spiral shape to form convolute fluid channels, covers on the spiral ends of said channels, an outer and an inner annular'rim on each cover forming an annular mould, and a metal of a lower point of fusion than said walls and said cover, said metal filling said mould and the spiral ends of said channels between the spiral edges of said walls, said cover and fusible metal being removable from said spiral ends as a unit when the fusible metal is melted, saidrimsservingl to retain the melted metal.

2. In a heat exchanger having heat transmission walls of sheet metal having spiral shape to form convolute iiuid channels, a closure of fusible metal between the spiral edges of said walls, and acover on said fusible metal closure, said fusible metal having a lower point of fusion than said Walls, said cover forming a casting-mould for said closure removable from said edges and constructed to retain said fusible metal while in liquid form when the cover is removed, and one of said channels having a fluid connection open-` ing through said cover.

3. In a heat exchanger having heat transmission walls of sheet metal having spiral shape to form convolute :duid channels, a closure of fusible metal between the spiral edges of said walls, a cover on said fusible metal closure, and a pipe for fluid connected to one of said channels, said fusible metal having a lower point of fusion than said walls, said cover having a central opening for said pipe and forming a casting-mould for said closure removable from said edges and constructed to retain said fusible metal while in liquid form when the cover is removed.

4. In a heat exchanger having spiral sheet metal heat transmission walls forming convolute fluid channels, closure means for the spaces between the edges of said walls including a body of low fusion point metal extending between said edges and a cover member having a surface confronting said edges shaped to form a depression for confining a pool of said low fusion point metal on said cover member when said body of metal is in molten condition.

NER T.

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