US 3367406 A
Description (OCR text may contain errors)
Feb. 6, 1968 G. VONK ETAl. 3,367,406
HELICAL WOUND STRIP REGENERATOR Filed Aug. 18, 1965 b 1:1 1:; E :l c: :I 1::1 1:: l: j L l C, E E :Il E E s 1:! :l
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FIC-3.3 FIGA INVENTOR GERBEN VON K HERMEN ZWAGERMAN BY l F i; GENT Unite States Patent Oilice 3,357,4@6 Patented Feb. 6, 1968 3,367,406 HELICAL WUND STRIP REGENERATGR Gerben Vonk and Hermen Zwagerman, Emmasiugel,
Eindhoven, Netherlands, assguors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Aug. 18, 1965, Ser. No. 480,695 Claims priority, application Netherlands, Aug. 20, 1964, 6ft- 9,596 2 Claims. (Cl. 16S-l0) ABSTRACT F THE DISCLOSURE A regenerator for use in devices operating at very low temperatures and having a helical wound slotted strip Iwith ribs thereon to form narrow ducts located perpendicular to the plane of t-he slots in the strip.
The invention relates to a regenerator comp-rising la housing with one or more filling masses arranged therein under pretension which lling masses are formed by a wound strip of a perforated material.
IThis known regenerator has the advantage that between the various flow ducts in the regenerator, transverse exchange .of medium is possible. A further advantage is that as a result of the perfor-ations the heat conductivity of the strip of material in the direction of llow of the regenerator is reduced.
A drawback of this known construction, however, is that adjacent turns of the filling mass will become to engage one another, as a result of which the heat transmitting surface is reduced. This draw-back is more prominent Aaccording as the material of the strip is softer.
Regenerators which have to operate in the very low temperature range must have a filling mass which is manufactured from a material which has a comparatively high specific heat at the said low temperatures. The materials which are to be considered for the said purpose are all rather soft. In addition, the said regenerators must have a very high space factor, it being required for the material to be distributed as evenly as possible to ensure a large heat transmitting surface.
The regenerator accord-ing to the invention meets all the said requirements and is characterized in that the material from which the strip is manufactured, has a high specific heat at very low temperatures, the strip being provided with ribs extending at right angles to the longitudinal direction of the strip. The ribs ensure that also in 'the case of a 4taut winding, the successive turns do not engage one another. As a result of this a particularly evenly distributed filling mass is obtained. In a further preferred embodiment of the regenerator according to the invention, the material of the strip is lead.
According to a further favourable embodiment of the device according to the invention, the strip h-as a thickness of approximately 100,11. (100 microns) and the ribs have a height of at most 50p., the perforations being `formed by slots which are arranged in rows extending in parallel with one another and in the longitudinal direction of the strip, the mu-tual distance between the rows being approximately 200;. and the width of the slots being in the order of magnitude of 50p..
The slots enable the medium, which in the regenerator according to the invention flows in narrow ducts between two turns and two ribs, to ovv from one duct into the other duct. As a result of the above dimensions a regenerator has been ,obtained with a very evenly finely distributed lilling mass, a large heat-transmitting surface and a high space factor of approximately 80 to 90%.
The present regenerator may be manufactured according to the invention by tirst rolling a strip of material 'by tmeans of a first shaped rolling device so that a number of recesses arranged in parallel rows is formed the bottom of which has a smaller thickness than the strip, the strip then being subjected to an etch-ing treatment by which a layer of material is removed of which the thickness at least corresponds to the thickness of the bottom of the recesses, the strip then being passed through a second 'shaped rolling dev-ice which provides the strip with ribs.
According to the invention, before subjecting the strip of material to the etching treatment it may be provided on one side with a coating layer which is not attacked by the etching agent. This results in a .saving of material because in this case a layer of material is etched away only :on one side.
A device for performing the said method comprising la lirst shaped rolling device which is constructed from a number of plates o'f a harder material yand a number of plates of a harder material which are alternately arranged on a shaft, the radius of the softer plates being smaller than the radius of the harder plat-es by substantially the |thickness of the strip, the harder plates being prov-ided with recesses at regular distances .and the device comprising an etching bath and a second shaped rolling device for providing ribs in the strip of material.
`In this oase the harder plates of the tirs-t shaped rolling device :have a thickness in the order of magnitude of 50p, and the softer plates have a thickness of .approximately 200a, the plates, after having been arranged on the shaft, being turned-off and provided with axial notches, the assembly being the subjected to an etching treatment or an electro-lytic treatment so that the difieren'ce in diameter between the harder plates and the softer plates is substantially t-wice the thickness of the strip of material to be processed. As a result of this it is reached, that during the provision of the recesses, the strip of mate'rilal is readily forced against the base plate. According to the invention, the material for the harder plates is steel land that for the softer plates is copper.
In order that the invention may readily be carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawing, in which:
FIGURES la, lb and 1c diagrammatically show three yperpendicular cross-sectional views of Ia strip of material suitable to be rolled to a regenerator filling mass.
lFIGURES 2a and 2b diagrammatically show a plan view .and a cross-sectional view respectively of a regenerator lilling mass consist-ing of a coil strip of material as shown in FIGURE l.
|FIGURE 3 diagramfmatically shows a shaped rolling device `for providing recesses in a strip of material.
FIGURE 4 diagrammatically shows a side elevation of a plate of the shaped rolling device shown in FIGURE 3.
lReferring now to FIGURE 1, reference numeral 1 denotes a strip of a material which at very low temperatures still has 4a comparatively high specitic heat, Ifor example, lead. The strip 1 is provided with a number of slots 2, which are arranged in rows. The strip further comprises a number of ribs 3. In a practical embodiment of the strip the thickness is e while the ribs have a height of 40a. The slots 2 have a width of 50a, while the distance between the rows of slots is ZOO/r After w-inding the strip on a core 4, a particularly even and nely distributed filling material with a very high space factor is obtained with these dimensions. The coiled strip is diagramtmatically shown in FIGURE 2. From this figure is appears that the successive turns are kept spaced by the ribs 3. As a result of this, narrow ducts 5 are created between the turns and each pair of ribs. In this type of regenerator it is of great importance that the medium can 3 flow trom one duct into the other duct. Tfhis ow is possible in the filling mass according to the invention as a resultof the slots 2. In addition, the slots 2 restrict the thermal conductivity of the strip in the direction of flow. In this manner an extremely readily operating regenerator for operating at very low temperatuers is obtained.
Asa result of the very small dimensions, the provision of the slots is particularly diicult. This is done by rst passing the strip through a shaped rolling device which provides recesses in the strip. The bottoms of the recesses are then removed by etching.
The shaped rolling device for providing the recesses is fdiagrammatically shown in FIGURE 3. This shaped rolling device comprises a shaft 6 on which a number of plates 7 and 8 are alternately arranged. The plates 7 are manufactured from copper and have a thickness which corresponds to the distance between the rows of slots. The pla-tes S are manufactured irom steel and have a thickness which corresponds :to the width of the slots. The plates 7 and 8, after lhaving been provided on the shaft 6, a-re turned-01T so that they have the same diameter. Slots are then provided at regular distances in the plates 7 and 8 as is shown in FIGURE 4 for `one plate 8.
The coiled strip is then dipped in an etching bath. The etching agent will attack the plates 7 of copper more rapidly than the steel plates 8. After some time, the plates 7 have a diameter which is smaller than the diameter of the plate 8 by twice the thickness of the strip 1. In this comparatively simple manner a shaped rolling device is obtained with which recesses of the desired smlall dimensions can be provided in the strip.
T'he ribs 3 can be provided on the strip by means of a suitably shaped roll-ing device.
The invention provides a regenerator which operates yreadily in the low temperature range, as well as a method of and a device for manufacturing the said regenerator.
What is claimed is:
`1. A regenerator having a medium tlow therethrough comprising a housing, a lling mass in said housing constituted lof a helically ywound strip having spaced slots therein, said Wound strip being of a material having a 'high specific heat at relatively low temperatures, said strip of material being provided with ribs extending at right angles to the longitudinal direction of said strip whereby narrow ducts are formed parallel to the longi- `tudinal axis of said wound strip, said slots and ducts being substantially perpendicular to each other, and the medium flow through said slots being perpendicular to the medium ow through said narrow ducts, said strip having a thickness of approximately 100g, the ribs having a height of at most 50M, said slots being arranged in substantially parallel rows and extending in the direction 'of the lonigtudinal axis of said strip, the distance between adjacent rows being about 200,11. and the width of each of said slots being about 50a.
2. A regenerator as claimed in cla-im 1 wherein said Ihelically wound strip is lead.
References Cited UNITED STATES PATENTS 3,200,877 8/1965 Lehmer et al. 165-4 3,216.484 dll/1965 Gifford 165-4 FOREIGN PATENTS 1,059,461 11/1953 France. 1,324,372 3/1963 France.
ROBERT A. OLEARY, Primary Examiner.
A. W. DAVIS, JR., Assistant Examiner.