Heat exchanger II

Abstract

A heat exchanger comprises a stack of mutually spaced apart plates. The plates are separated by respective spacings therebetween. Alternate spacings respectively provide a flow path for a first fluid and a second fluid. The heat exchanger further comprises a first header for inflow of the first fluid and a second header for outflow of the first fluid. The first and second headers are connected to the plate stack by flexible tubular ducting means.

Claims

1. A heat exchanger comprising a stack of mutually spaced apart plates separated by respective spacings therebetween, wherein alternate spacings respectively provide a flow path for a first fluid, hereinafter the first fluid flow path, and a flow path for a second fluid, hereinafter the second fluid flow path, the heat exchanger further comprising a first header and a second header, the first header for inflow of the first fluid and the second header for outflow of the first fluid, wherein respective cells are formed by opposed pairs of the plates, the spacing between the plates of these pairs constituting all or part of the first fluid flow path, and the spacing between the respective cells constituting all or part of the second fluid flow path, the first and second headers being connected to the stack, wherein at a first end of the first fluid flow path the first header is connected to the stack by flexible tubular ducting in the form of metallic tubes which connect each cell with said first header, the ducting providing fluid flow between the cells and said first header, as well as a mechanical connection therebetween which maintains strength and yet is able to flex by virtue of being arranged to follow a tortuous path, the flexibility of the ducting permitting independent flexing of cells relative to said first header during heat exchanger start-up and operation, wherein the cells are also connected to said first header by at least one support member, the at least one support member not conveying fluid and comprising a joint that enables relative movement between said first header and the respective cells, with at least one degree of freedom.

2. The heat exchanger of claim 1, wherein the joint comprises a first jointing arrangement at a first end of the heat exchanger, allowing one or more rotational degree of freedom and at least one translational degree of freedom.

3. The heat exchanger of claim 1, wherein said metallic tubes connect each cell with said first header in pairs and the shapes in each pair are symmetrical about an axis of symmetry.

4. The heat exchanger of claim 3, wherein the axis of symmetry is substantially parallel to the direction of fluid flow in the first fluid flow path.

5. The heat exchanger of claim 1, wherein the tortuous path comprises a curved portion.

6. The heat exchanger of claim 1, wherein the tortuous path comprises a portion having at least one helical turn.

7. The heat exchanger of claim 1, wherein the tortuous path comprises at least one angled region.

8. The heat exchanger of claim 1, wherein the plates have two opposite sides substantially parallel to the direction of the first fluid flow path and are joined respectively by two connecting sides at each end of the first fluid flow path and the metallic tubes communicate with the spacings defining the first fluid flow path at one or both of the two opposite sides.

9. The heat exchanger of claim 8, wherein the metallic tubes communicate with the spacings defining the first fluid flow path at one or both of the two opposite sides substantially parallel to the direction of the first fluid flow path.

10. The heat exchanger of claim 1, wherein the plates have two opposite sides substantially parallel to the direction of the first fluid flow path and are joined respectively by two connecting sides at each end of the first fluid flow path and the metallic tubes communicate with the spacings defining the first fluid flow path at one or both connecting sides.

11. The heat exchanger of claim 10, wherein the metallic tubes communicate with one or both connecting sides via a common duct.

12. The heat exchanger of claim 1, wherein the mean hydraulic diameter of each metallic tube is from 0.5 to 2 times the average plate-to-plate distance of the spacings representing the first fluid flow path.

13. The heat exchanger of claim 1, wherein the average length of the metallic tubes is from 0.1 to 2 times the width of the plates normal to the flow direction of the first fluid flow path.

14. The heat exchanger of claim 1, wherein the ducting is arranged to direct inflow of the first fluid to the spacings defining the first fluid flow path in a direction from 90° to 30° relative to the direction of flow in the first fluid flow path.

15. The heat exchanger of claim 14, wherein an inflow diverters is located at or near the entry region of the spacings defining the first fluid flow path to enhance uniformity of flow in said fluid flow path.

16. The heat exchanger of claim 14, wherein an outflow diverters is located at or near the exit region of the spacings defining the first fluid flow path, to enhance uniformity of flow out of said first fluid flow path.

17. The heat exchanger of claim 1, wherein the plates are provided with surface projections for enhancing heat transfer.

18. The heat exchanger of claim 17, wherein the plates are arranged in a plurality of groups each comprising at least two plates, the surface projections being in the form of a plurality of groups of pins, the pins in each group being arranged to bridge plates of a respective plate group.

19. The heat exchanger of claim 18, wherein the groups of plates are formed by the opposed pairs of plates from the respective cells.

20. The heat exchanger of claim 1, wherein the first header is connected to a source of the first fluid, ducting being provided for feeding the second fluid from a source of the second fluid to the second fluid flow path, wherein the first fluid at source has a pressure equal to or greater than that of the second fluid at source.

21. The heat exchanger of claim 1 wherein said first header is at a cold end of the cells.

22. The heat exchanger of claim 1, fabricated as a modular arrangement, the stack being a module or unit comprising a fraction of the total number of plates in the heat exchanger.

23. A heat exchanger comprising a stack of mutually spaced apart plates separated by respective spacings therebetween, wherein alternate spacings respectively provide a flow path for a first fluid, hereinafter the first fluid flow path, and a flow path for a second fluid, hereinafter the second fluid flow path, the heat exchanger further having first and second headers, the first header for inflow of the first fluid and the second header for outflow of the first fluid, wherein respective cells are formed by opposed pairs of the plates, the spacing between the plates of these pairs constituting all or part of the first fluid flow path, and the spacing between the respective cells constituting all or part of the second fluid flow path, the first and second headers being connected to the stack, wherein at a first end of the first fluid flow path the first header is connected to the stack by flexible tubular ducting in the form of metallic tubes which connect each cell with said first header, the ducting providing fluid flow between the cells and said first header, as well as a mechanical connection therebetween which maintains strength and yet is able to flex by virtue of being arranged to follow a tortuous path, the flexibility of the ducting permitting independent flexing of cells relative to said first header during heat exchanger start-up and operation, wherein the stack includes at least one support member connected to said first header, the at least one support member not conveying fluid and comprising a joint that enables relative movement between said first header and the stack, with at least one degree of freedom.

24. The heat exchanger of claim 23 wherein said first header is at a cold end of the cells.

25. The heat exchanger of claim 23, fabricated as a modular arrangement, the stack being a module or unit comprising a fraction of the total number of plates in the heat exchanger.

Description

(1) The present invention will now be described in more detail by way of the following description of the preferred embodiments and with reference to the accompanying drawings in which:

(2) FIG. 1 shows a perspective view of a first embodiment of a heat exchanger according to the present invention;

(3) FIG. 2 shows a cross-section through part of two pairs of plates of the heat exchanger shown in FIG. 1, detailing a plate-and-pin arrangement;

(4) FIG. 3 shows a variant of the embodiment depicted in FIG. 1, having support struts between the plates and headers;

(5) FIG. 4 shows a cross-sectional detail of a hinging arrangement of the struts of the heat exchanger shown in FIG. 3;

(6) FIG. 5 shows a cylindrical (radial) embodiment of a heat exchanger according to the invention, designed for axial flow;

(7) FIG. 6 shows a configuration of a heat exchanger according to the present invention, adapted for radial flow;

(8) FIG. 7 shows another embodiment of a heat exchanger according to 10 the present invention, analogous to that shown in FIG. 6 but with curved plates in involute form;

(9) FIG. 8 shows a detail for directing inflow of high pressure fluid into a heat exchanger according to the present invention;

(10) FIG. 9 shows an arrangement for directing outflow of high pressure 15 fluid out of a heat exchanger according to the present invention;

(11) FIG. 10 shows a variant of the embodiment of FIG. 1, employing pusher bars;

(12) FIG. 11 shows a detail of the variant of FIG. 10, depicting the hinging of the pusher bars;

(13) FIG. 12 shows a partial cross-section through an embodiment of a heat exchanger according to the present invention, having a first alternative arrangement of tubular interconnection between the header and the body of the heat exchanger;

(14) FIG. 13 shows a partial cross-section through another embodiment of heat exchanger according to the present invention with a second alternative arrangement of interconnection between the header and body of the heat exchanger;

(15) FIG. 14 shows a partial cross-section through yet another embodiment of a heat exchanger according to the present invention with a third alternative configuration of interconnection between the header and the body of the heat exchanger;

(16) FIG. 15 shows a still further embodiment of a heat exchanger according to the present invention, having a fourth alternative configuration of tubular interconnection between the header and the body of the heat exchanger; and

(17) FIG. 16 shows a partial cross-section through a heat exchanger of FIG. 12, depicting the inflow arrangement within a cell.

(18) In the following embodiments, the heat exchanger components may be formed of any material appropriate to the specific intended application, having regard to the operational temperature. However, example materials include stainless steel (such as SS 316) or a nickel-based alloy (such as Inconel 625).

(19) There is shown in FIG. 1, a first embodiment of a heat exchanger 1 according to the present invention. A first header (pipe) 3 is arranged for inflow of a first cooling fluid and a second header (pipe) 5 is arranged for the outflow of that first fluid, after it has been heated in the heat exchanger. The body of the heat exchanger consists of a stack 7 of mutually spaced-apart substantially rectangular plates arranged between the inflow header 3 and the outflow header 5 of the first fluid with opposite edges respectively facing the headers. The plates are arranged in spaced-apart pairs 9, 11, 13, etc., which are sealed around their edges so as to provide respective sealed units, save only for ducting for inflow and outflow of the first fluid as will be described further herein below.

(20) The pairs of plates are also mutually spaced apart providing spacings 15, 17, 19, etc., therebetween which constitute a fluid flow path for a second fluid which thus flows over the outsides of the plate pairs. The inside of the inflow header 3 communicates with the inside of respective plate pairs 9, 11, 13, etc., by respective flexible tubes 21, 23, 27, etc., which follow a partially curved path from the inside of the lower header 3 to the bottoms of the inside of the plate pairs 9, 11, 13, etc., that opposing lower corners thereof.

(21) The upper opposing corners of the plate pairs 9, 11, 13, etc., are respectively connected from the inside of the plate pairs to the inside of the outflow header 5 via flexible tubes 29, 31, 33, etc., but these tubes follow a shorter and more tightly angled path than that of the lower tubes 21, 23, 27, etc.

(22) High pressure cooling fluid is directed into one end 35 of the lower header 3 as denoted by arrow 37. It then passes through the flexible ducting formed by flexible pipes 21, 23, 27, etc., to the lower corners of the insides of the plate pairs 9, 11, 13, etc., after which it flows upwardly inside the plate pairs to leave via the top corners of those pairs and to be conveyed via the upper flexible tubes 29, 31, 33, etc., to the inside of the upper header 5 to pass out of the end 39 thereof as denoted by arrow 41.

(23) Hot fluid at a pressure equal to or lower than that of the cooling fluid is passed down between the plate pairs as shown by arrow 43, for example from a first plenum chamber to exit at the bottom via another plenum as denoted by arrow 45.

(24) As shown now in FIG. 2, the precise form of construction of the plate pairs such as 11, 13 can be seen. The other plate pairs (not shown) have like construction and only part of the length of the plate pairs is shown in FIG. 2.

(25) These plate pairs 11, 13 consist of respective first and second plates 51, 53 and 55, 57. High pressure cold fluid is injected into the respective spaces 59, 61 between the plates 51, 53 and 55, 57, etc., respectively, from the tubes 23, 27, etc. This is shown by the arrows 63, 65. At the same time, the low pressure hot fluid is injected into the spaces outside the plates as denoted by the arrow 43.

(26) Each pair of plates 11, 13, etc. has arranged there through, a plurality of pins 67, 69, etc. and 71, 73, etc. These pins both bridge the spaced apart plates 51, 53 and 55, 57, etc., and also extend into the spacings 15, 17, 19, etc., between the plate pairs. However, the ends 75, 77, etc., of the pins do not actually touch but in each spacing between the plate pairs, they face each other end-to-end but separated by gaps 79, etc., therebetween.

(27) A variation of the embodiment shown in FIG. 1 is depicted in FIG. 3. Here, the same reference numerals are used for like integers. The difference is that the upper header 5 is connected to the upper edges 81, etc., of the plate pairs by respective connection members 83, etc. Similarly, the lower header 3 is connected to the lower edges 85, etc., by respective lower connection members 87, etc.

(28) In a preferred form of construction, connection members 83, etc., have the form of construction shown in FIG. 4 which depicts just one of these members 83. Here, the connection between the upper edges 85, 87 of a plate 91 is made to the upper header 5 by the connection member 83. This member 83 comprises a hinge pin (not visible) passing through the member 83 and a lug 95, forming part of the header 5. In use, the rotational motion between the plate pair which includes plate 91 and the header 5 is thereby permitted, as depicted by arrow 101.

(29) FIG. 5 shows a second embodiment of a heat exchanger 110 according to the present invention. A plurality of planar plate pairs 111, 113, 115, etc., are arranged in radial fashion around an axis of symmetry 117. The whole arrangement is thereby generally cylindrical but with a space through the middle of the arrangement bounded by the inner edges 119, 121, etc. of the plate pairs.

(30) The plate pairs 111, 113, 115, etc., are also provided with pins in the manner shown in FIG. 2 but for clarity, these are omitted from the drawing of FIG. 5.

(31) Annular headers 123, 125 are respectively arranged adjacent the end edges 129, 131, etc., of the plates such as shown for plate 113 in FIG. 5. These headers are supplied by a source of high pressure cooling fluid (not shown). They feed the high pressure fluid into the corners 133, 135, etc., (as shown for plate 115) via flexible tubes 134, 136 in the same manner as depicted in FIGS. 1 and 3.

(32) If header 23 constitutes the source of high pressure hot fluid and header 125 represents the outflow of that fluid, then high pressure flow is in the direction depicted by arrow 137 and low pressure flow is through the spaces 139, 141, etc., between the plates in the direction of the arrow 143.

(33) FIG. 6 shows another embodiment of a heat exchanger 150 according to the present invention which is analogous to that shown in FIG. 5 in that a plurality of planar plate pairs 151, 153, 157, etc., are arranged in radial fashion with their innermost edges 159, etc., facing inwardly towards a central space. Thus, again, a cylindrical configuration is adopted. In this arrangement, a pair of inner annular headers 161, 163 are arranged and connected by flexible tubes 165, 167, etc., to the corners 169, 171, etc., of the plates, such as shown for one plate 173. A pair of outer annular headers 175, 177 is also provided, respectively connected to the outermost corners 179, 181, etc., of plates 151 etc by means of flexible connections 183, 185, etc. Thus, high pressure cooling fluid may be directed radially through the insides of the plate pairs, either outside to inside or vice versa. Counter-flow low pressure hot fluid may similarly be passed radially through the spaces 187, 189, etc., between the plates by suitable manifold means (not shown).

(34) FIG. 7 shows another arrangement 190 like that in FIG. 6 for radial flow. The same reference numerals are used for like integers but instead of planar plate pairs 151, 153, 157, there are provided curved plate pairs 191, 193, 197, etc., in involute form. Operation is essentially analogous to that for the embodiment shown in FIG. 6.

(35) FIG. 8 shows one preferred form of high pressure feed to the spaces between the plates. A partial cross-section of the space between two adjacent plates such as a plate 201 is shown. Rows 203, 205, etc., of pins 207, 209 are arranged so that the pins in one row are staggered relative to the pins in each adjacent row and the rows run in a direction at right angles to the general direction of high pressure flow between the plates as denoted by arrow 211. One of the flexible tubes denoted by numeral 213 for directing high pressure fluid into the gap between the plates 201 and its adjacent plate (not shown) is positioned to inject the high pressure fluid at an angle θ with respect to the lines of rows of pins so that relative to the direction of high pressure flow denoted by arrow 211, the high pressure fluid is injected at an angle of approximately 25°.

(36) A baffle 215 is also situated between the plates at an angle φ relative to the direction of the rows of pins to assist in bending the fluid flow towards the direction 211 of flow between the plates.

(37) Instead of, or in addition to using the angle baffle plate 215 to direct inflow as shown in FIG. 8, a means of directing the flow from the heat exchanger core into the outflow flexible tubes is shown in FIG. 9. As depicted in this drawing, a flexible connector tube 221 communicates with an exit zone 223 between a pair of plates, only the lower plate 225 being shown. The plate pair is bridged by rows 227, 229, etc., of pins 231, 233, etc., again, as with the arrangement of FIG. 8, the pins in adjacent rows being staggered relative to one another.

(38) The direction of high pressure fluid flow outflow is indicated by arrow 235, 237 being the arrow indication of the direction of high pressure flow in the space between the plates. Baffle plates, bridging the main plates 225, etc., of the plate pair, block regions of exit of fluid from the pin matrix, as denoted by numerals 239, 241, 243 and 245. However, gaps are situated between these baffle plates to allow the fluid to exit the pin matrix. These gaps 247, 249, 251, etc., become progressively wider as distance from the outflow flexible pipe 221 increases. This arrangement thereby fulfils essentially the same function as that of the continuous baffle plate 215 as depicted in the embodiment of FIG. 8, but in reverse.

(39) FIG. 10 shows a modification of the embodiment of FIG. 1. In FIG. 10, the same reference numerals are used to depict like integers which appear in FIG. 1. However, in this variant, a pair of pusher bars connects the two headers 3, 5. The first pusher bar 261 connects one end 263 of the upper header 5 with the corresponding end 265 of the lower header 3. A second pusher bar (not visible) connects the other end 267 of the upper header 5 with the corresponding end (not visible) of the lower header 3.

(40) Hingeable connection is made at the point of connection with the lower header 3 as denoted by numeral 269 and at the point of connection with the upper header 5, as denoted by numeral 271.

(41) A detail of this hingeable connection 269 between the pusher bar 261 and the lower header 3 is shown in FIG. 11. A lug 273, which is part of the lower header 3, is situated in a space 275 formed in the lower part of the pusher bar 261 and a hinge pin 277 passes through the pusher bar and lug. Thereby, rotational motion around the axis of the pin which is orthogonal to the axis of symmetry of the headers, is permitted as depicted by arrow 279.

(42) A partial cross-section of another embodiment heat exchanger according to the present invention is shown in FIG. 12. This embodiment is substantially the same as that shown in FIG. 1, except that at the inflow (cold) end, the 10 shape of the tubes (equivalent to integers 21, 23, 27 in FIG. 1) is different. Optionally, the same shapes may also be adopted for the tubes connecting the heat exchanger cells and the outflow (hot end) header.

(43) In FIG. 12, there is shown a single plate 301, which is seen from the outside, i.e. the surface visible is in the second fluid flow path. The plate comprises a left hand side 303 and a right hand side 305, which sides are substantially parallel to the direction of fluid flow in the first fluid flow path. They are interconnected by a connecting side 307 which is nearly at right angles to the two sides 303, 305. A connecting duct 309 channels fluid into the first fluid flow path at a position substantially midway along the connecting side 307. The communal central duct 309 into the first fluid flow path, from the header 311, via two flexible connecting tubes, designated by numerals 313 and 315 respectively. These tubes leave the header at the respective positions 317 and 319 and are bent via respective curved portions 321, 323 which lead into respective straight portions 325, 327 which interconnect with the central duct 309. The curved portions 321, 323 bend the tubes through substantially 180°.

(44) FIG. 13 shows an arrangement similar to that in FIG. 12 and the same reference numerals are used to denote like features. However, in this case, the header 311 is linked to the central duct 309 by respective tubes 331, 333, which have only slight curvature along substantially their entire length and bend through an angle of approximately 20° overall.

(45) FIG. 14 shows another alternative arrangement. The components are analogous to the embodiments shown in FIGS. 12 and 13 except in this case, the plates, one of which is designated by numeral 341, has left and right substantially straight sides 343, 345, substantially parallel to each other and to the direction of flow in the first fluid flow path but joined by a different shape of connecting side. The outer surface of a cell is constituted by the plate 341 and is therefore in a second fluid flow path. In this case, the two sides of the plate are joined by a connecting side 347 which is substantially symmetrical and has two outwardly directed substantially straight side portions 349, 351 which are joined by a convex curve portion 353. The region of transition between the straight portions 349, 351 of the connecting side 347 and the convex portion 353 have protrusions 355, 357 respectively, which constitute the point of entry of cold fluid into the space between the plates which is the first fluid flow path. These points of interconnection are connected by regularly curved tubes 359, 361 (having outward curvature) to provide a fluid flow path from a header 363 into the first fluid path in the body of the heat exchanger.

(46) The alternative arrangement shown in FIG. 15 has substantially rectangular plates, one of which is shown from the outside (second fluid flow path view) as designated by reference numeral 371. It has opposite sides 373, 375 which are substantially parallel to each other and to the direction of flow in the first fluid flow path. The sides are interconnected by a connecting side 377. Into the first fluid flow path at the corners 379, 381 of the plate 371 (between the two sides 373, 375 and the connecting side 377) are connected inflow ducts 383 and 385 respectively. These connect to the corners of the cell on the sides 373, 375. These inflow ducts 383, 385 are contiguous with respective tubes 387, 389 which convey fluid from a header 391. Each tube 387, 389 comprises an approximately straight portion 393, 395 extending from the header 391 and then at the position of a 90° turn towards the heat exchanger plate, each is provided with a single helical turn 397, 399, after which each tube 387, 389 joins the entry ducts 383, 385.

(47) In all of the embodiments of FIGS. 12-15, each plate has substantially the same shape, and the tubes connecting the headers and the cells also have substantially the same shape. Optionally, the same configuration of the interconnecting tubes is used at the outflow end, or alternatively, they may have the shape of the outflow tubes shown in the embodiment of FIG. 1.

(48) FIG. 16 depicts how air may be directed in a heat exchanger having the form of construction shown in FIG. 12. More visible in FIG. 16 than in FIG. 12 is the fact that the connecting side 307 is not absolutely straight along its length but is angled slightly outwardly from each end towards the central duct 309. Also the plane of cross-sectional cut is different from that in FIG. 12. The plane of cut is between plates of the first fluid flow path. Arranged inside the (and each other) cell is arranged pins protruding orthogonally to each plate within the cell. The pins, depicted by numerals 401, 403, etc., are arranged in rows 405, 407, etc. The pins in each row are offset relative to the pins in each other row, in the manner depicted in, for example, FIGS. 8 and 9. A baffle plate 411 is provided across the first row of pins 405 at the midpoint of that row, opposite the inflow aperture 409 of the inflow duct 309 and has a width just a little greater than that inflow aperture 409. This enables the fluid entering the cell to be dispersed along the rows of pins so that flow is made more nearly uniform across the width of the cell.

(49) In the light of the described embodiments, modifications of those embodiments, as well as other embodiments, all within the scope of the present invention as defined by the appended claims, will now become apparent to persons skilled in the art.