US3383751A

US3383751A - Method of providing a wall around a unitary mass of gas-permeable material for constructing a heat exchanger or a regenerator

Info

Publication number: US3383751A
Application number: US447778A
Authority: US
Inventors: Johannes Rudolphus Van Geuns; Dirne Adrianus Petrus
Original assignee: US Philips Corp
Current assignee: US Philips Corp; North American Philips Co Inc
Priority date: 1964-04-15
Filing date: 1965-04-13
Publication date: 1968-05-21
Anticipated expiration: 1985-05-21
Also published as: DK121411B; DE1296479B; NL6404045A; NL144365B; SE305223B; CH444897A; BE662459A

Description

M y 1968 J. R. VAN GEUNS ETAL 3,383,751

ITARY MASS OF GAS-PERMEABLE MATERIAL FOR CONSTRUCTING A METHOD OF PROVIDING A WALL AROUND A UN HEAT EXCHANGER -OR A REGENERATOR Filed April 13, 1965 FIG.2

FIGJ

INVENTOR JOHANNES R.VAN GEUNS f ADRIANUS P DIRNE I BY AG E 3 mm F United States Patent 3,383,751 METHOD OF PROVIDING A WALL AROUND A UNITARY MASS OF GAS-PERMEABLE MA- TERIAL FOR CONSTRUCTING A HEAT EX- CHANGER OR A REGENERATOR Johannes Rudolphus van Geuns and Adrianus Petrus Dime, Emmasingel, Eindhoven, Netherlands, as-

signors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. 13, 1965, Ser. No. 447,778 Claims priority, application Netherlands, Apr. 15, 1964, 64-4,045 9 Claims. (Cl. 29-1573) ABSTRACT OF THE DISCLOSURE A method for providing a regenerator with a wall. The regenerator mass is constituted of gauze or fine screening with a wall soldered to the periphery. Since the wall is in excellent contact with the regenerator mass, no leakage occurs.

The invention relates to a method of providing a wall around a packet of gas-permeable material, for example, a gauze packet, in particular for regenerators or heatexchangers manufactured by this method.

Known heat exchangers and rcgenerators are constructed from a gas-permeable mass surrounded by a Wall. In regenerators, the regenerator mass serves for alternately absorbing heat from the medium which performs a reciprocating fiow through the regenerator and then giving on said heat to the medium again, in heatexchangers the gas-permeable medium serves to effect a better heat-exchange between the wall and the medium.

A drawback of these known constructions is that the connection between the wall and the gas-permeable mass is often insufiicient, so that part of the medium flows along the gas-permeable mass. This is particularly disadvantageous tor regenerators. For heat-exchangers also this poor connection is disadvantageous because the thermal contact between the mass and the wall becomes worse, as a result of which the heat-exchange is adversely influenced.

In order to avoid the above poor connection bet-ween the filling material and the wall it is known to solder the filling material to the wall after enveloping it. In this method, however, there is no possibility of checking the adherence and it has been found in practice that many times the filling material was not soldered to the wall at several points.

-It is the object of the invention to provide a method with which a readily connecting wall can be provided around a gas-permeable mass.

The method according to the invention is characterized in that a mass of gas-permeable material is provided at its surface with a layer which contains at least one metal and, if desired, one or several other elements. The layer is subjected to 'a thermal treatment so that a homogeneous wall is formed.

The gas-permeable mass usually is formed by a number of stacked wire nettings which are thoroughly compressed.

According to the invention, a wall is provided on the surface of the said gauze mass. In this case, the wall grows, as it were, on the material of the mass, so that the whole surface is thoroughly connected to the wall. The surprising fact in this case is that during the provision of the wall the provided material does substantially not penetrate into the gauze mass but adheres to the surface of the said mass.

3,383,751 Patented May 21, 1968 The provision of the wall may be effected, for example, by electrolytic deposition, but it is alternatively possible to manufacture the wall by moulding.

It is of importance, particularly for regenerator-s, that the wall has a low thermal conductivity in the direction of flow of the medium.

In order to accomplish the aforesaid, a further favourable embodiment of the method according to the invention is characterized in that the constituents of the provided layer are chosen so that during the thermal treatment the said constituents are converted, by diffusion, int-o a poorly heat-conducting alloy.

The constituents of the layer may be the combinations copper-nickel; silver phosphorus; copper-nickel-zinc; copper-silver-phosphorus. After diffusion these combinations give a poorly-conducting material. For some heatexchangers the wall need not be poorly heat-conducting in the direction of flow. In general, non-alloyed metals will then be chosen for the material of the wall.

Using the method according to the invention results in a wall which readily .joins the filling material and the thermal conductivity of which in the direction of flow is small. A further advantage is that the thickness of the wall may be chosen to be as is desired.

According to a further embodiment of the method according to the invention the mass of gas-permeable material is provided at its surface with layers of different metals, the choice of the said metals being such that after the thermal treatment a comparatively poorly heat-conducting wall is obtained. According to the invention, the provided layers may alternatively consist of copper or nickel. These two metals have a ready thermal conductivity. After the thermal treatment, the copper and nickel are converted, by diffusion, into constantan, which has a poor thermal conductivity. Instead of copper and nickel it is alternatively possible to use combinations of other metals or metal alloys. For example, the combinations silver-phosphorus; copper-nickel-zinc; copper-silver-phosphorus readily meet the requirements imposed.

A further favourable embodiment of the method according to the invention is characterized in that the surface of the mass of gas-permeable material has applied thereto a paste of various metal powders and a binder, the metal powders being chosen such that after the thermal treatment a comparatively poorly heat-conducting metal is formed, after which the formed wall is sealed mechanically by pressure.

A favourable embodiment of the method according to the invention is characterized in that the surface of the packet is covered with a paste of one or several metal metal powders with a hinder, the composition of the metal powders being such that after the thermal treatment a comparatively poorly heat-conducting metal is obtained with a melting range, the temperature during the thermal treatment lying only slightly above the beginning of the melting range.

When the powder consists of several metals, diffusion will occur during the thermal treatment while also the powder grains soften on the outside, as a result of which the grains fuse to a homogeneous tight wall. It is alternately possible to apply already a powder of grains of the desired metal on the surface. Naturally, in that case no diffusion will occur during the thermal treatment, while the grains fuse to a tight homogeneous wall. The surprising fact in this case is that it has been found that, during the thermal treatment, the metal powder does not flow away nor is it drawn by capillary action into the mass.

The term metal in this connection is understood to mean herein not only a metal which consists of one metallic element, but also metal alloys which substantially consist of one or several metallic elements, if desired mixed with one or several non-metallic elements.

A further favourable embodiment of the method according to the invention is characterized in that the surface of the mass is covered with a paste of one or several metal powders and a binder, after which the mass is wrapped with one or several metal wires in a manner such that at least one closed Winding layer is formed. The layer is then further covered with a paste of one or several metal powders, after which the assembly is subjected to a thermal treatment and the temperature is chosen to be high so that it lies somewhat above the melting range of the wall material.

In this manner a wall is obtained which, in addition to a poor thermal conductivity in the direction of flow, can demonstrate a sufiicient rigidity against high pressures without it being necessary for the layers of poorly heat-conducting material to be thick. This is of particular importance for heat-exchangers because in this case a wall is desired which has a low thermal resistance at right angles to the direction of flow.

In order that the invention may readily be carried into effect, it will now be described in greater detail with reference to the drawing in which several heat-exchangers are shown diagrammatically.

FIGS. 1 to 3 diagrammatically show in cross-section a number of heat-exchangers having structures in accordance with the teachings of the present invention.

In FIG. 1 reference numeral 1 denotes a filling regenerator material in which the mass consists of wire nettings built up in layers and pressed on each other. Layers 2 and 3 are deposited by electrolytic deposition on the periphery of this filling material. These layers consist alternately of copper and nickel. After a thermal treatment in which diffusion occurs the layers 2 and 3 can no longer be distinguished. Then the whole wall has a homogeneous composition, in which, as a result of the diffusion, gauze regenerator mass is imbedded in the wall. The copper and nickel together have formed constantan. This constantan has a poor thermal conductivity. The filling material 1 is now surrounded by a wall which has a particularly good contact with the filling material.

In FIG. 2, a layer 4 is applied on the periphery of the filling material 1. This layer consists of a paste of metal powders and a binder. The combinations of metal powder may be copper-nickel and copper-silver-phosphorus. When a thermal treatment is used in which the temperature lies below the melting point or melting range of the metal powders, the powders diffuse and a porous wall is formed. By a mechanical treatment this wall is sealed by pressure. It is alternatively possible to choose the composition of the powder so that an alloy with a melting range is obtained. This may be done by mixing powders of different elements in the correct composition or by pulverizing an existing alloy. By heating just above the melting range of the ultimate alloy, the paste flows to a dense, poorly-conducting homogeneous wall.

FIG. 3 finally shows how first a layer of paste 5 of metal powders is applied on the surface of the filling material 1. Then a wire 6, for example, of V A-steel, is wound around the assembly so that a closed wound layer is obtained. A second layer of paste 7 is provided on the winding layer. Then the assembly is heated so that the layers of

paste

5 and 7 fuse and diffuse to form dense homogeneous walls with poorly heat-conducting properties. In this manner a strong wall is obtained which is poorly heat-conducting in the direction of flow of the medium and, dependent upon the choice of the material of the wire, is readily thermally conducting in the transverse direction.

It has been found that by a correct choice of the metal 70 powders the temperature of the thermal treatment may be kept low so that sintering of the gauze mass does not occur.

So with the method according to the invention it has become possible to manufacture in a comparatively simple manner walls of regenerators and heat-exchangers which are readily joined to the filling material.

What is claimed is:

1. A method of producing a heat exchanger by forming a wall about a mass of gas permeable material comprising the steps of applying to the surface of said mass a layer containing at least one metallic constituent capable of forming an alloy with said mass, thermally treating said layer to form a homogeneous wall consisting of said alloy bonded to said mass and mechanically pressure sealing said homogeneous wall.

2. A method of securing a mass of gas-permeable material to a heat exchanger wall as claimed in claim 1 wherein the said layer is such that during said thermal treatment the said constitutents thereof are converted into a poorly heat conducting metal alloy by diffusion.

3. A method of securing a mass of gas-permeable material to a heat exchanger wall as claimed in claim 2 wherein the surface of the mass is provided with a plurality of layers of different metals, said metals being such that after thermal treatment thereof a relatively poor heat conducting wall is formed.

4. A method of securing a mass of gas-permeable material to a heat exchanger wall as claimed in claim 3 wherein said layers consisting alternately of copper and nickel.

5. A method of securing a mass of gas-permeable material to a heat exchanger wall as claimed in claim 1 wherein said layer is applied by electrolytic deposition on the surface of said mass.

6. A method of securing a mass of gas-permeable material to a heat exchanger wall as claimed in claim 1 further comprising providing a binder, said mass having a paste constituted of at least one metal and said binder being applied to the surface of said mass.

7. A method of securing a mass of gas-permeable material as claimed in claim 1 further comprising providing a binder, said mass having a paste, constituted of at least one metal and said binder being applied to the surface of said mass, said poor heat-conducting metal being provided with a melting range, the temperature during said thermal treatment being slightly above the beginning of said melting range.

8. A method of securing a mass of gas-permeable material as claimed in claim 7 wherein said metal powder is of a relatively poor heat-conducting alloy with a predetermined melting range and said binder.

9. A method of securing a mass of gas-permeable material as claimed in claim 1 wherein the surface of said mass of gas-permeable material is covered with a first layer of paste of at least one metal power and a binder, wrapping at least one metal wire around said mass and said first layer in a manner such that at least one closed winding layer is formed, applying a second layer of paste of at least one metal powder and a binder to said closed winding layer, and subjecting the assembly to said thermal treatment.

References Cited UNITED STATES PATENTS 2,573,951 11/1951 Brennan 29-l82.2 2,993,264 7/1961 Grenoble 29-527 3,081,530 3/1963 VVlodek 29-527 3,192,073 6/1965 Jominy et a1. 29-527 3,315,350 4/1967 Kent 29527 JOHN F. CAMPBELL, Primary Examiner.

PAUL M. COHEN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,383,751 May 21, 1968 Johannes Rudolphus Van Geuns et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 26, "packet", first occurrence,

should read mass Column 3, line 37, before "gauze" insert the Column 4, line 54, "power" should read powder Signed and sealed this 7th day of October 1969.

(SEAL) Attest:

Edward M. Fletcher, J1. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents