US2469758A - Heat exchanger - Google Patents

Description

4. F. ALCOCK HEAT EXCHANGER May 10, 1949.

2 Shasta-Sheet 1' lfiled Feb. 7, 194'! Fla/2.-

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A llorney May 10, 1949.

Filed Feb. '7, 1947 J. F. ALCOCK HEAT nxcmdmi;

2 Sheets-Sheet 2 FIG. 4.

Inventor aha. Bywamw, G01 ll. v-wam-w Attorney Patented May 10, 1949 HEAT EXCHAN GER John Forster Alcock, North Lancing, England, assignor to Harry Ralph Ricardo, London, England, a British subject Application February 7, 1947, Serial No. 727,194 r In Great Britain February 14,1946

2 Claims. (01. 257-6) This invention relates to heatexchangers of the regenerative type-in which there is a rotatable member having a matrix of heat-conductive material which is subdivided into cells and traversed by two fluid streams which are caused to flow alternately through the matrix. One of these streamsimparts heat to the matrix while the other fluid stream abstracts heat therefrom, the rotation of the matrix positioning each portion thereof in succession so that it will be traversed alternately by the two fluid streams.

Hitherto this type of regenerator has been used in cases wher the pressures of the two fluid streams differ little if at all, and consequently it has been fairly easy to minimise leakage from one stream to the other as for instance by employing relatively simpl means for sealing the structure. In a. gas turbine plant however wherein the exhaust gases'from the turbine are used to heat the cold gas delivered by a compressor, and also in other apparatus such as an oxygen producing plant, the pressures of fluids in the two streams passed through the heat exchanger may be very different and more effective methods of sealing become necessary. The object of the present invention is to provide such sealing that a heat exchanger of this type may be used for these purposes.

According to this invention th improved heat exchanger comprises in combination an annular matrix rotor, a toroidal casing in which the rotor fits and is rotatably mounted, a plurality of disclike partitions which being spaced apart circumferentially divide the matrix into sections these partitions extending across the matrix and the interior of the casing in a radial direction relatively to the axis about which the matrix is rotatable, two openings through each wall of the casing disposed diametrically opposite or nearly so with respect to the axis of the apparatus and the openings in one part of the casing wall lying opposite to the openings in another part of the wall, thes openings serving respectively for the inflow and outflow of the two fluids which pass alternately across'the casing and through the matrix as the cells therein are successively positioned opposite these openings while the matrix rotates, and tunnel-shaped passages runn ng circumferentially within the contour of the matrix rotor and around the cells therein with the partitions extending across these passages. Preferably the partitions between the sections in the matrix rotor carry spring rings resembling piston rings which constitute seals preventing fluid flow clrcumferentially between the fluid streams pass- 2 I ing through the matrix. Conveniently for the purpose of imparting rotation to the matrix rotor it carries an annular toothed rack which lies in a plane normal to the axis of the rotor and at least two toothed pinions lie in the same plane and mesh with this rack and being driven impart rotation to the rotor. These pinions are geared together and each has a part which is cut away so as to clear the partitions as they pass, while enabling the driving of the rotor to be maintained.

The cross-section of the toroidal casing and the corresponding contour of the matrix rotor is preferably circular as being convenient for manufacture, but it may be elliptical or have some other similar shape which is a smooth continuous curve adapted to be sealed by discs and rings in the manner described.

Rotation may be imparted to the matrix rotor in various ways from a suitable source of power. For example where the heat exchanger is used in conjunction with a gas turbine rotation may be transmitted to the pinions mentioned above through reduction gearing from the turbine shaft. The rotation of the matrix rotor may be continuous or intermittent as may be suitable in the apparatus in which the heat exchanger is employed.

The accompanying drawings illustrate, some' what diagrammatically, the main features in con structions which may be employed when carrying the invention into practice. In these drawings,

Figure 1 is a side elevation of one construction with a part of the casing broken away to show the gearing through which the rotor is driven.

Figure 2 is a section on the line 2--2 in Figure 1 looking in the direction of the arrows.

Figure 3 is a section on the line 3-3 in Figure 1 looking in the direction of the arrows.

Fi ure 4 is a sectional elevaion in a plane containing the axis of a modified construction in which the passages for fluid flow throu h the matrix are arranged so that this flow is in a radial direction through the matrix in contrast to flow in the axial direction as in the construction shown in Figures 1, 2 and 3.

Referring to Figures 1. 2 and 3, the matrix rotor is built up of a series of sim lar cellular sections A each of which ap ears as substantially rectangular in cross section, as seen in Figures 2 and 3, while in side elevation. as seen in Figure 1 each section has a quadrantal form. The sections A are separated by circular partitions B and the whole rotor when the sections are assembled has an annular form which adapts it to lie and rotate within a flxed toroidal casing C. This casing is made in two similar parts as may be seen in Figure 2 with the parts connected by a joint C which lies in a plane normal to the axis of the apparatus. In this casing the peripheries of the partition discs B in the matrix rotor lie adjacent to th inner surface of the wall of the casing with the cellular sections A extending between these partitions. In this construction the sections A are so arranged that the fluid 'fiow through the cells in the sections is in a direction parallel to the axis about which the rotor rotates. Along each outer side of each matrix section there runs in a circumferential direction a tunnel-like passage D and D with the disc partitions B lying across these passages which appear, as seen in the sectional views 2 and 3 as segments of circles each being bounded by the wall of the casing C with the flat side of the matrix section lying as the chord. The opposite ends of the numerous cells in each matrix section A open into parts of these passages which lie between the radial partitions B. Any risk of fluid leakage along these passages and from one matrix section to the next is prevented by providing each of the circular partitions B with one or more sealing rings 13 each of which resembles a piston ring and makes leak-tight contact with the wall the casing C.

In each of the opposite side walls of the casing C there are two arcuate openings E, E which in this case are similar in size and shape, but need not be of the same size. The openings in each pair in this construction are situated diametrically opposite in relation to the axis of the apparatus as may be seen in Figure 1. Each of these openings in one side wall of the casing lies opposite to a similar opening in the other side wall so that fluid can flow through these openings and the matrix sections A between them in a direction parallel to the axis of the apparatus. The opposite sides of all the matrix sections A with the ends of the cells running through these sections come successively into register with these openings E, E so that one fluid can flow, in through one opening E at one side of the casing C, through the cells in a section and out through the corresponding opening E in the opposite side of the casing. The return flow of the other fluid will then be into the opening E in the side of the casing from which the first fluid has flowed out through the opening E, back through the cells in each matrix section and out through the corresponding opening E in the opposite side of the casing. There are suitable separate connections with the two openings E and with the two openings E and through these connections the two fluids which are to be dealt with in the heat exchanger are caused to flow so that as the matrix rotor is rotated one fluid will pass in one direction through each matrix section A and then as the rotor rotates the second fluid will pass in the opposite direction through the sam matrix section. The arcuate unbroken portions C of the side walls of the casing C which lie between the openings E, E as seen in Figure 1, are of such circumferential length that in these parts of the toroidal casing C which are thus completely closed in these will always be at least one partition B as, the rotor is turning. In this way these'partL tions B with their piston rings 13 will form an eiiective seal which will prevent leakage from one fluid stream into the other.

Around the outer periphery of the matrix rotor there is a toothed rack F the continuity of which is interrupted at each partition with its piston ring. Meshing with this rack are two toothed pinions G which are rotatably mounted and enclosed in a casing part C which projects from the periphery of the toroidal casing C as may be seen in Figures 1 and 3. Thes two pinions both lie in that plane normal to the axis of the apparatus in which is the rack F, as can be seen in Figure 3, and the pinions are spaced apart in the circumferential direction as can be seen in Figure 1. Each pinion has a part of its periphery cut away at G which allows the pinion as it rotates to clear the partitions B and their piston rings B The pinions are simultaneously driven and they are at such a distance apart and their cut away parts arranged in such rotational relationship that as they are driven and in turn rotate the matrix rotor continuity in the transmission will be maintained since when the cut away part G of one pinion is clearing a partition B and thus ceasing to engage the rack F the other pinion will still be in engagement with this rack andwill thereby continue to impart rotation to the matrix rotor. The pinions are conveniently geared together and driven at such speed as ma be suitable from some source of power.

The piston rings may be ground to fit the toroidal bore of the casing, but with rings of normal width the usual cylindrical grinding will generally give a good enough fit, enabling them quickly to bed down to a toroidal form. In either case it is desirable to peg or otherwise flx the rings so that they cannot rotate in their grooves, since a part of the ring which has bedded down to, say, the inside of the torus may not be the correct shape for the outside, and vice versa.

It is to be understood that the flow of the fluids through the matrix may be either in a. direction substantially parallel to the axis of the apparatus or in a radial direction or in a conical direction, that is to say intermediate between axial and radial. As already mentioned in the form of the apparatus illustrated in Figures 1, 2 and 3 the passages for the inflow and outflow of the fluids run in the direction of the axis of the apparatus, but a different arrangement is shown in Figure 4. Here the sections A in the built up matrix rotor are placed with the cells therein running radially instead of in the axial direction as in the construction shown in Figures l, 2 and 3. There are then provided two passages in" and E positioned adjacent and leading into the inner part of the casing C these passages running in the axial direction but at their inner ends each turning radially outwards towards the ends of the cells in the matrix sections A. .At the outer part of the casing are corresponding passages E and E for fluid outflow and inflow these passages running in the axial direction but at their inner ends turning radially inwards so that each leads towards the outer ends of the cells in the matrix sections A. The passages E E are situated at diametrically opposite places on the periphery of the casing C and the axis of all four passages E E E and E lie in the same radial plane. With such an arrangement the cold fluid wi11 flow, say, in through the passage E then radially outwards through the matrix sections A, and thence away through the passage E At the same time the hot fluid going in the opposite direction will enter through the passage E and after flowing radially inwards through the cells in the matrixsections will pass away through the passage E Such an arrangement is in some cases structurally convenient .in that it has the advantage of making the inner part of the apparatus the cooler and the cross section at all points can be proportional to the gas volume, that is to say its absolute temperature thus maintaining constant velocity through the matrix.

What I claim as my invention and desire to secure by Letters Patent is:

l. A regenerative heat exchanger of the moving matrix type comprising a toroidal casing of approximately circular cross-section, an annular rotor carrying matrix sections rotatable within the casing and conforming to the cross-section of the casing, a series of discs constituting partitions between the matrix sections and spaced apart circumferentially, each said disc having a peripheral groove, and a spring ring lying in each said groove and constituting a seal for preventing circumferential fluid flow between said matrix sections. v

2. A heat exchanger according to claim 1, said rotor having an annular toothed rack disposed peripherally thereof and in a plane normal to the axis of the rotor, and at least two toothed pinions rotatably mounted in the plane of and in mesh with said rack, said pinions each having a partcut away to clear pass the pinions.

JOHN FORSTER ALCOCK.

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

OTHER REFERENCES The .Ljunstrom Air Preheat/er, Figure 2 on page 5; lines 8 to 12 of page 9. Nov. 1939.

said partitions as they

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