US2757907A

US2757907A - Heat exchanger

Info

Publication number: US2757907A
Application number: US194850A
Authority: US
Inventors: Samuel B Williams
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1950-11-09
Filing date: 1950-11-09
Publication date: 1956-08-07
Anticipated expiration: 1973-08-07

Description

S. B. WILLIAMS HEAT EXCHANGER l 'Aug..7, 1956 2 Sheets-Sheet 1 Filed Nov. 9, 1950 s. B. WILLIAMS HEAT EXCHANGER Aug. 7, 1956 2 Sheets-Sheet 2 Filed Nov, 9. 1950 IN VEN TOR. 54ml@ l/x/I: was

United States Patent O HEAT nxcrrANGEn Samuel B. Williams, Birmingham, Mich., assigner to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application November 9, 1950, Serial No. 194,850

7 Claims. (Cl. 257-6) The present invention relates to heat exchangers and more particularly to heat exchangers of the regenerative type in which there is a rotatable element subdivided into cells which contain heat absorptive material and which are traversed by two uid streams caused to iiow alternately through the core material. One of these streams imparts heat to the heat transfer material while the other iuid stream abstracts heat therefrom, the rotation of the element positioning each celled portion thereof in succession in order that it will be traversed alternately by the two fluid streams.

Hitherto, a rotative type regenerator has been used in cases where the pressure of the two uid streams diifers little if at all, and consequently it has been fairly easy to minimize leakage from one stream to the other as, for instance, by employing relatively simple means for sealing the structure, the seal length thereof being of substantial magnitude in comparison to the face area of the absorptive material. In a gas turbine plant, however, where the exhaust gases are used to heat the gas delivered by the compressor and also in other apparatus such as an oxygen producing plant, the pressures of the fluids in the twov streams passed through the heat exchanger may be very different and more effective methods of sealing and of reducing the comparative seal length become necessary.

An object of the present invention is to provide such sealing that a heat exchanger of this type may be used for these purposes especially where proportionately large face entrance area for the heat transfer material is required.

According to a feature of the invention is the provision of cell passages of extended length which can accommodate long walls of pervious heat transfer material which are disposed obliquely to the entrance and discharge directions of ilow of fluid with respect to the cell passages.

According to a further feature a heat exchanger is provided in which the core face entrance area is relatively large in comparison to the effective length of the seal around the high pressure fluid ports.

According to yet a further feature of the present improvement, when the core angle of disposition is about 8, then approximately iive times as much lluid can be handled under conditions of laminar flow than can be handled by a conventional heat exchanger of the same seal length having the core face entrance area disposed normal or transverse to the passage entrance and discharge direction. If turbulent flow is contemplated, an attempt to flow ve times as much iluid through the conventional transversely disposed core face entrance area will result in a pressure drop of the factor live squared times as much as the pressure drop for the improved heat exchanger having a core angularity of about 8 and roughly the same seal length. If the core angularity is decreased to approximately in the improved heat exchanger, the multipiic'ation factor for the improved behavior and effectiveness as compared to a transversely disposed core eX- changer is ten times under circumstances of laminar flow; under circumstances of turbulent ow then, a llow of ten times the uid through the transversely `disposed cores will result in the same total heat transfer through both exchangers but ten squared times the pressure drop will result across transverse cores in comparison to the improved cores as set at approximately 5 angular-ity. The above figures are submitted as representative for particular designs considered, due allowance having already been taken into account for ydead length in the cell passages devoted to space occupied by necessary ramps and fairing for the angled cores.

According to still a further feature of the invention, a rotating element is provided of which the rotating ends of the metallic cells are in contact with the rubbing seal and the core material is not itself subject to frictional wear. Hence the core material may be of ne texture and fragility if desired and may be free from the burden of wear.

According to another feature, provision is made to seal the end of the rotating element of a heat exchanger by a resiliently urged face seal which can adjust itself for optimum sealing effect.

According to still another feature is the provision of an easily fabricated structure which may be constructed of sheet metal as one chief material, the structure thereby lending itself to certain economies of manufacture.

Other features, objects, and advantages will either be specifically pointed out or will become apparent as reference is made to the following detailed description taken in conjunction with the accompanying drawings wherein:

Figure l is a layout of a typical power plant in which the heat exchanger of the instant invention iinds application;

Figures 2 and 3 are longitudinal and transverse sectional views respectively, of the heat exchanger;

Figure 4 is a perspective view of the cell passages and ramp-curved core material therein;

Figure 4A is a perspective View of the cell passage shown in Figure 4 as viewed in the opposite -direction to show the structural relationship between the core and the other axial side of the cell passage walls;

Figure 5 represents an enlarged perspective of a portion of a core material found suitable for these applications;

Figures 6 and 7 show modified arrangements of the core material within the cell passages; and

Figure 8 is a transverse section through a heat exchanger element of slightly modified construction.

In respect to Figure l particularly, included in the turbine power plant layout is a gas turbine 10 having a gas inlet 12 and exhaust 14. Inlet 12 is supplied with energy gases from a burner`16 having a fuel line 18 therefor. Turbine 10 may be provided with a main output shaft 20 and a compressor shaft 22 for driving a compressor and/ or auxiliaries. Compressor 24 has an extension shaft 26 around which is disposed an air inlet bell 28 for passage of air to be compressed. The compressed air is delivered by the compressor through an outlet 29 to a heat exchanger 30 having a high pressure inlet 32 for the compressed air. Within exchanger 3d, heat is added to the compressed air and the air still under pressure is delivered in a preheated state through the regenerator outlet elbow 34 to burner 16. Regenerator 30, preferably of the counterflow type, has another inlet 36 for receiving exhaust gases from outlet 14 of turbine 10. Regenerator Si), after abstracting heat from these exhaust gases, delivers them through an elbow 38 into a discharge pipe 40. Regenerator 30 is provided with a rotating element, later to be set forth in detail, which is keyed to a shaft portion 42 at one end of the regenerator mounting a drive device 44 for rotating the rotating element. At the opposite end of regenerator 30 is another shaft portion 46 in a flanged end 48 provided for access internally into the regenerator.

In regard to Figure 2, shaft portions 46 and 42 are provided respectively with wide rimmed parts 50 and 52 Patented Aug. 7, 1956 which support inner and outer cylinders 54 and 56 constituting portions of a rotating heat exchanger element 57. Parts 50 and 52 are faced off to provide a radially extending flange such as indicated at 51 on part 50. At the ends of rotating element S7 may be provided radially extending

circumferential anges

58 and 60. Shaft portion 46 has a nut or other suitable fastener 62 at the end thereof and is journalled in a bearing 64. An end sheet 66 for the heat exchanger supports bearing 64 and is attached to the case 70 of the heat exchanger by suitable fasteners 63 through the ange 43 thereof. Casing 70 of heat exchanger 30 is provided with annularly grooved circumferential seal 72 of the labyrinth type, which cooperates with one side of the rotating flange 58. On the other side of flange S a rubbing seal 76 provides a scal along its sliding surface 74.

At the small end of seal 76, which may be circular, is provided a bellows 7S having one end attached to the circular portion seal and the other end firmly secured at 79 to end sheet 66 of the regeuerator casing. Within bellows 78 is provided a resilient device 80 which resiliently urges seal 76 into contact with ange 53. Seal 76 is retained for axial motion in the chamber defined by sheet metal parts S2, 83 and $4, 85. Shaft portion 46 is connected for rotation through the parts such as 54 and 56 forming rotating element 57, with the shaft portion 42 at the similar opposite end of the regeuerator. Extending to a point adjacent shaft portion 42, a seal 86 is resiliently urged into contact with flange 60 on the rotating element. As respects the seal material of Figure 2, seals 76 and 86 may be, without necessarily excluding other suitable materials, formed of metal impregnated graphite, sintered bronze impregnated with a dry lubricant such as molybdenum disulphide, or sintered iron impregnated with a dry lubricant. Shaft portion 42 is journalled in a bearing 88 supported by an end sheet 90 firmly secured as by welding 91 to case 70. Drive device 44 for shaft portion 42 may comprise a pulley having a V groove 92 over which is trained a V belt 94 appropriately driven through gearing which may tind its source of power through either shaft 20, 22, or 26 as shown in Figure l.

Extending longitudinally of the rotating element 57 and being generally disposed about the central axis 96 of the regenerator are provided a plurality of cell passages 100. Each cell 102 forming a cell passage 100 receives internally thereof pervious walls of a suitable core material 104 held between the respective top and

bottom walls

106, 108 of the cell. The end of the core members 104 are secured as by brackets 110 to the opposite non-parallel walls later to be described in connection with individual cells 102.

With regard to Figure 3, the section shown of regenerator 30 is taken through one of the end Seals thereof and will be observed to be in a direction such as to show flange 48 and fasteners 68. Centrally of flange 48 and extending toward the observer is the case 70, radially inwardly from which projects labyrinth seal 72. Between labyrinth seal i 72 and end flange 60 of the rotating element appears a portion of end flange 50 of the rotating clement. The

sheet metal members

82, 83 and 84, 85 are shown to define a space in which is received the seal formed with a central opening 87 therein. Registering with central opening 87 are, a plurality at a time, cell passages 100 defined by their respective cells 102. The pervious walls provided by the core members 104 will be observed to be attached at their ends by suitable brackets or ramps 110 to the opposed non-parallel side walls 112 of the cells 102. The wedge-shaped portions of the seal 86 laterally of opening S7 will be observed to occlude the ends of certain passages whereas the passages between the widened rim portion 52 and flange 60 without the bounds of the seal 86 are completely exposed. The top and

bottom walls

106 and 108 of cells 102 will be observed in Figure 3 to be generally adjacent respectively the flange 60 and the wide rim 52 shown exposed.

The operation of the device of Figures l, 2, and 3 may be described as follows. High pressure gas from the compressor is passed from inlet 32 through the plurality of cell passages 100 which register with the sealed central opening 87. Seal 76, resiliently urged into sliding contact with flange 5S and with a faced off portion 51 of the widened rim 50, serves positively to seal the high pressure gas in the upper cell passages 100. Circular bellows 73 at the end of seal 76 prevents escape of any compressed gas past the securing fastener 79. Seal 86 likewise provides a sealed connection for the heated compressed gas leaving through elbow 34 of the regenerator for the burner. inasmuch as element 57 is adapted to be rotatably driven during operation of the regenerator, the cells 102 are undergoing a continuous turning process such that the heat transfer cores 104 as they are cooled, are continually being replaced in the high pressure passages in rotation. The heat supplied the pervious walls of cores 104 is abstracted from the turbine exhaust gases led into the regenerator through inlet 36. This exhaust gas is of relatively low pressure compared to the relatively high pressure of the fluid in the high pressure side of the regenerator but no commingling of gas will result because of the effectiveness of the components cooperating with seals 76 and 86. The exhaust gas travels along the lower cell passages 100 through the pervious walls of the core material 104 and out the elbow 38. It is to be noted that labyrinth seal 72 in case 70 cooperates with flange 53 to prevent the low pressure exhaust gases from bypassing the lower cell passages 100.

In respect to Figures 4 and 4A, the cell passages 100 are shown as defined in isometric by the individual cells 102. Cells 102 have top and

bottom walls

106 and 108 and non-parallel side walls or plates 112. Received in each cell is a core member 104 providing a wall of pervious material adapted to be alternately heated and cooled due to being subjected alternately to the flow of relatively hot and cold gases. Each core member 104 is along its top and bottom edge secured to the respective top and

bottom walls

106 and 108 of cells 102. At either end of the core members 104 are secured to the generally radial, non-parallel opposed side walls 112 of cells 102. The end connections may suitably be effected by ramps 110 which are shown in full lines in Figures 2 and 4A, but which appear in phantom view in Figure 4 and which will be seen to be wall-attached to the radial walls 112 and to fit into the extended end portion 114 shown in full in Figure 2, but in phantom view in Figure 4 and provided for the cell structure 102. The extended end portion 114 while present in Figure 2, is designated by numeral and shown in phantom lines in Figure 4 for the reason of clarity in exposing the structure of the foreshortened ends of the cell structure 102 and also the end of the core member 104. The core member 104 presents a core face entrance area of considerable lateral extent generally indicated at 105. inasmuch as the plane of the core 104 is disposed relative to the adjacent plate 112 so as to dene an included angle A indicated at 107, the core face area is substantially greater than the cross sectional area of the individual cell passages 100. Since the cell passages 100 and the core members 104 have, in a transverse plane, one dimension in common, the total surface area aiorded for a given cross sectional area of cell passage 100 bears a ratio to the latter said cross sectional area which is roughly equal to the numerical cosecant of the angle A. That is to say, the longest linear dimension of the core 104 corresponds to the hypotenuse of the right triangle which includes the angle A, and the cell linear width corresponds to the side of the right triangle opposite the included angle A; therefore, the ratio of the core face area to the cell cross section area is roughly equal to the cosecant of the angle A because these two areas bear substantially the same relationship to one another as do the linear dimensions just noted. If then the dead length of the ramp is taken into account, the multiplication factor of core face area to passage cross section is considerably above unity for an angle A of 30 and for an angle of 8 is about the order of ve times. The multiplication factor for an angle A of is roughly ten times. As approached from another criterion, the situation is such that since the cross section passage area in overall combined form is roughly a function of the effective rubbing seal length, the eective core face entrance area by use of the improved heat exchanger under consideration exceeds in proportion the total seal length by a plurality of times. Hence a relatively smaller heat exchanger according to the improved version is able to present a relatively large core face entrance area in proportion to its radial size and length of seal.

Within the broader aspects of the invention, the individual cells l02 may each be formed from circular tubes which are shaped to assume the general configuration of the cells of Figures 4 and 4A. It is to be noted that the wall thickness of elements 104 is only a fractional part of the circumferential dimension of each cell passage 100.

As regards Figure 5, a mode of locating the upper and lower edges of each core element 104 to the upper and lower walls of the cells is represented. Core elements 33.04 may be of an integrated structure formed of ilat strips 116 which alternate with corrugated strips 118. These strips may be of the order of thickness of 11/2 thousandths inches and of a width corresponding to the thickness of the members 104 in Figures 4 and 4A. The corrugations of strips 113 cooperate with flat strips lle to dene passages l2t) of a dimension roughly of the order to accommodate passage, say of a small needle. Strips 116 and lll are held together in a channel member 122 between the opposed legs of the latter. Channel 122 is attached to upper wall 106 of the individual cell at the general angularity to side wall 'll2 as indicated by angle A in Figures 4 and 4A. The gas passes along the passage 100 in Figure 5 through the pervious wall provided by capillary openings 120 and continues along the passage l00 on the opposite side of the wall. Strips llo and 11S may be formed of stainless steel, carbon steel, or a carbon steel coated with a suitable surfacing material such as aluminum. Within the broader aspects of the invention7 the material for pervious walls 104 may be constituted by sheets of a porous ceramic extending substantially longitudinally of each cell, or mats of steel wool suitably retained between screening which runs generally longitudinally of the cells.

In Figure 6 each cell passage 200 is provided with a pair of core members 204. The ends of each core member are secured to the non-parallel opposed side Walls 27.2 of cells 202 by means of ramp brackets 210. One core member 204 terminates about half way along the length of a passage 200 and the other core member 204 begins about half way along the passage 200 and terminates at the extreme end thereof. Gas entering the passage 200 in one direction progresses from the chamber 220 to the chamber 222 through one pervious wall provided by a core member and further progresses from the chamber 222 between the core members through the other core member to the chamber 224. Then the gas is discharged through the opening at the end of the cell 202. Oppositely directed gas of course takes a vice versa route.

In Figure 7, the cells 302 are of a modified type having four pervious wall members 304 per cell. The extreme core members 304 are attached respectively to the top and

bottom walls

306 and 308 of cells 302. At all other ends, core members 304 are joined to one another alternately at junction points such as 320. In order to progress through each passage 300 the incoming gas must pass at least through one wall thickness of the pervious material of members 304.

As respects Figure 8, a slightly modied form of heat exchanger 430 has anged fasteners 468 and a case n 470. Internally of the case is a rotating element having an end flange 460 approximately half of which is free of the seal 486. The central opening of seal 486 is indicated at 487 to expose the ends of a plurality of cell passages 500 arranged in two circumferential rows, one within and one Without the other. The individual cells 502 in both rows contain each a core means as at 504 attached to the walls thereof by bonding or by suitable brackets.

The portions of the rubbing seals shown in Figures 3 and 8 will be observed to have a segmental central opening. The seal itself, however, undergoes a transition in cross section from one axial end to the other thereof and as described in connection with Figure 2, reduces to substantially a circular cross section adjacent the bellows 78 and the spring 80.

Variations within the spirit and scope of the invention described are equally comprehended by the foregoing description.

l claim:

l. In a rotary regenerator unit for a gas turbine power plant adapted to be installed in the engine compartment of a wheeled vehicle, a circular housing comprising coaxially disposed inner and outer housing portions, said housing having an axis of rotation and spaced end surfaces disposed perpendicularly with respect to said axis, a plurality of circumferentially spaced baffles extending in a generally radial direction and interconnecting said inner and outer housing portions thereby defining a plurality of passages, and core structure interposed within each of said passages, the core structure for each passage comprising a pervious wall extending from one side of the passage to an opposite side thereof, one edge of said Wall being located relatively close to one end surface of said unit and the opposite edge thereof being located relatively close to the other end surface of the unit thereby providing an effective gas passage area for each core structure which exceeds in magnitude the transverse cross sectional area of its associated passage, the thickness of said Walls being substantially less than the spacing between two other juxtaposed passage sides.

2. In a rotary regenerator unit for a gas turbine power plant adapted to be installed in the engine compartment of a wheeled vehicle, a substantially cylindrical housing with concentric inner and outer housing portions, said housing having an axis of rotation and spaced end surfaces disposed perpendicularly with respect to said axis, a plurality of partitions extending in a generally radial direction between said housing portions and defining two sides of a plurality of passages for accommodating the passage of gasses through said unit, and a core structure interposed within each of said passages, each of said core structures comprising at least one llat pervious matrix element secured to one side of its associated passage, said matrix element forming an acute angle with said one passage side, one edge of said matrix element being located relatively close to one end surface of said unit thereby providing an effective gas passage area for each matrix element which exceeds in magnitude the transverse cross sectional area of its associated passage, said one passage side being circumferentially spaced from an opposed passage side, the thickness of said walls being substantially less than the radial spacing between said inner and outer housing portions.

3. In a rotary regenerator unit for a gas turbine power plant adapted to be installed in the engine compartment of a wheeled vehicle, a substantially cylindrical housing comprising concentric inner and outer housing portions, said housing having an axis of rotation and spaced end surfaces disposed perpendicularly with respect to said axis, a plurality of dividing plates extending in a generally radial direction between said concentric housing portions and dening a plurality of four-sided passageways for accommodating the passage of gases axially through the regenerator unit, at least one dat, pervious matrix element mounted in each of said passageways with one edge thereof being located relatively close to one end surface of said unit and with the other edge thereof being located relatively close to the other end surface of said unit, each of said matrix elements forming an acute angle with one side of its associated passageways thereby providing an eiective gas passage area for each matrix element which exceeds in magnitude the transverse cross sectional area of its associated passageway, said one passageway being radially spaced from its opposed side, the thickness of said matrix elements being substantially less than the circumferential spacing between said dividing plates.

4. In a rotary regenerator unit for a gas turbine power plant adapted to be installed in the engine compartment of a wheeled vehicle, a substantially cylindrical housing comprising concentric inner and outer housing portions, said housing having an axis of rotation and spaced end surfaces disposed perpendicularly with respect to said axis, a plurality of dividing plates disposed in a substantially radial position between said housing portions thereby defining a plurality of four-sided passageways for accommodating the passage of gasses axially through the regenerator unit, a pervious matrix wall mounted in each of said passageways and forming an acute angle with one of the sides of its associated passageway, one edge of said matrix wall being located relatively close to one end surface of said unit and the opposed edge of said matrix element being located relatively close to the other end surface of said unit thereby providing an effective gas passage area for said matrix element which exceeds in magnitude the transverse cross sectional area of its associated passageway, said one passageway side being circumferentially spaced from its opposed side, the thickness of said matrix element being substantially less than the radial spacing between said inner and outer housing portions, and means for mounting said unit for rotation about its central axis.

5. In a rotary regenerator unit for a gas turbine power plant adapted to be installed in the engine compartment of a wheeled vehicle, a substantially cylindrical housing having two end surfaces, a plurality of axially extending four-sided passages defined by said housing and situated in a circular row about the axis of said housing for accommodating the axial passage of gases therethrough, at least one pervious matrix wall interposed in each of said passages and forming an acute angle with two opposed circumferentially spaced sides of the same, one edge of each matrix wall being relatively close to one end surface of said unit and the opposed edge thereof being relatively close to the other end surface of said unit thereby providing an effective gas passage area for each matrix wall which exceeds in magnitude the transverse cross sectional area of its associated passage, the thickness of each matrix wall being less than the radial height of its associated passage and the Width of each matrix wall being equal to the radial height of its associated passage'.

6. In a rotary regenerator unit for a gas turbine power plant adapted to be installed in the engine compartment of a wheeled vehicle, a substantially cylindrical housing, said housing having an axis of rotation and spaced end surfaces disposed perpendicularly with respect to said axis, a plurality of passages formed within said housing in a circular row about the axis of said housing, at least one pervious matrix wall interposed in each of said passages, said walls forming an acute angle with two opposed sides of said passages, means for rotating said regenerator unit about its central axis, a pair of gas conduit means disposed at each spaced end surface of said housing, one of each of said pairs of conduit means being adapted to accommodate and to direct the flow of heated gases through a portion of said regenerator unit, the other of each of said pairs of conduit means being adapted to accommodate and to direct the ow of relatively cool gases through another portion of said regenerator unit, said pervious matrix walls being alternately heated and cooled by said gases upon rotation of said unit thereby effecting a thermal energy transfer from said heated gases to said cooled gases, the opposed edges of each matrix wall being located relatively close to one end surface and the other end surface of said unit respectively thereby providing an eiective gas passage area for each matrix wall which exceeds the magnitude of the transverse cross sectional area of its associated passage, the thickness of each of said 'matrix walls being substantially less than the spacing between two other juxtaposed sides of its associated passage.

7. The combination as set forth in claim 6 wherein each of said passages includes a fairing ramp secured to separate one of the passage walls for each of said passages at either end thereof, said ramps comprising a surface inclined at an acute angle with respect to its associated passage side, one edge of each matrix wall being received under each ramp.

References Cited in the le of this patent UNITED STATES PATENTS 1,781,303 Rydmark Nov. 11, 1930 1,871,166 Fahrbach Aug. 6, 1932 2,013,499 Meckeustock Sept. 3, 1935 2,229,691 Boestad Jan. 28, 1941l 2,337,956 Yerrick et al. Dec. 28, 1943 2,432,198 Karlsson et al. Dec. 9, 1947 2,469,758 Alcock May 10, 1949 2,480,248 Karlsson et al. Aug. 30, 1949 2,485,088 Ellis Oct. 18, 1949 2,503,651 Alcock Apr. 11, 1950 FOREIGN PATENTS 116,544 Austria Oct. 15, 1927 479,840 Great Britain Feb. 10, 1938 636,839 Great Britain May 10, 1950 957,953 France Mar. 1, 1950