US 3306353 A
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Description (OCR text may contain errors)
F. A. BURNE Feb. 28, 1967 HEAT EXGHANGER WITH SINTERED METAL MATRIX AROUND TUBES Filed Dec. 25. 1964 2 Sheets-Sheet 1 IN VENTOR mam/cm. B U/P/VE v zhy/a pat 6 W A TTOR/V V Feb. 28, 1967 F. A. BURNE HEAT EXCHANGER WITH SINTERED METAL MATRIX AROUND TUBES 2 Sheets-Sheet 2 Filed Dec.
FIG 16 ZZZ 1 N VEN TOR. FREDER/C/(A. BURN/5 jfl/ M FIG-7 A T TOPNEV United States Patent 3,306,353 HEAT EXCHANGER WITH SINTERED METAL MATRIX AROUND TUBES Frederick A. Burne, Hamden, Conn., assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Filed Dec. 23, 1964, Ser. No. 420,567
6 Claims. (Cl. 165164) ample, fins or corrugations across which pass the media between which the heat exchange is to take place. However, it has been found that greatly increased heat transfer surfaces can be achieved by instead employing a body of pervious material, or a porous body having interconnected voids. Such a body of pervious material presents a large number of faces for. heat exchange purposes, as well as other advantages to be discussed shortly.
By the instant invention there is provided a unique configuration and arrangement of such a pervious body within a heat exchanger which has been tested and found to result in greatly increased heat exchange properties. The concept of the instant invention may be employed in heat exchangers of any desired shape, but is particularly adapted to tubular heat exchangers. As known in the art, the use of heat exchangers of a tubular configuration is highly advantageous in certain environments where it is desired that the heat exchange take place wholly within the exchanger. The tubular heat exchangers commonly in use in such an environment are of the type known in the art as shell and tube, wherein a plurality of tubes con veying one heat exchange medium are arranged within a shell through which is circulated another heat exchange medium, with or without the use of bafiles to direct the flow, which is substantially axial along the tubes.
In the concept of the instant invention there is provided a heat exchanger in which not only the heat exchange area is increased but the flow of one of the media is directed in a path between and around a series of inner tubes, the medium flow being substantially perpendicular to the axes of the inner tubes. The advantages resulting from such flow are achieved by the provision of a pervious body completely encasing the series of inner tubes. By a particular configuration and arrangement of the tubes and the pervious body, to be discussed hereinafter, space is provided within the heat exchanger to serve as distribution and collection manifolds for the heat exchange media resulting in the desired flow. Furthermore, the instant heat exchanger may be made sufliciently compact so that it may be used in in-line installations, for example, within a radiator hose of an automobile cooling system.
As will be understood, various combinations of metals may be utilized in forming the heat exchangers according to the intsant invention; and accordingly the solid portions and the pervious body may be of the same metal or alloy, or the pervious structure and the solid member may be comprised of different compositions. For example, both the pervious body and solid portions may be formed of the same stainless steels, coppers, brass, carbon steels, aluminums or various combinations thereof. As will be evident, the ultimate use of the resultant structure determines the specific combination of alloys to be employed.
The production of the pervious body is most flexible; for example, it may be produced by a process wherein par- 'perature of the particulate material.
3,306,353 Patented Feb. 28, 1967 ice ticles, usually spherical, are poured by gravity into an appropriately shaped confined space and usually vibrated to cause the particles to compact uniformly. As is obvious, the choice of particle size will largely determine the size of openings in the resulting pervious body. The body of particles so packed is then treated in accordance with any of the well known metallurgy practices-cg, sintering, welding; brazing or soldering employing an appropriate coatingto produce a metallic bond between the particles. Thus, there is provided a pervious body whose bulk density, or apparent density, is but a fraction of the density of the metal or alloy from which the particles are obtained. Furthermore, such process result-s in a metallic bond between the pervious body and solid material around or within the body.
While the above described process is preferred in the instant invention, other processes may be employed. For example, it is possible to blend intimately a particulate material with either a combustible substance or a soluble material whose melting point exceeds the sintering tem- After the blend is compacted and treated to achieve a metallic bond, the combustible substance may be burned away or the soluble material removed by leaching or dissolving with a liquid. A still further method of producing the pervious body comprises melting a metal or alloy and casting it into the interstices of a loose aggregate of a particulate soluble material whose melting point exceeds that of the metal, preferably having a specific gravity of the molten metal. Upon solidification of the metal, a component is produced which contains the network of the soluble material interspersed within the solid metal which soluble material is thereupon removed by leaching or dissolving, leaving behind it interstices that interconnects and form a pervious network within the resultant metal body. A still further method of producing such pervious bodies comprises weaving or knitting metal wire into a mesh arranged in a plurality of layers. According to this process, a control of porosity is obtained by appropriate choice of wire diameters and openings arranged between adjoining wires as well as the juxtapositioning of superimposed layers of the woven or knit mesh.
It is to be understood that the concept of this invention need not be limited to the particular configuration indicated above. For example, a tube need not be exclusively employed; any desired shape of exchanger may be provided, with the inner tubes and pervious body shaped accordingly to fit. Furthermore, the tubes may be of any desired cross-section, any number of heat exchange media may be employed, the exchanger may be used for either heating or cooling, and the direction of flow of the heat exchange media may take a variety of pat-terns.
It is accordingly an object of this invention to provide a heat exchanger which is highly compact and yet capable of high efficiency and low pressure drop.
It is a further object of this invention to provide such a heat exchanger having a body of pervious material joined therein by a metallic bond.
It is a still further object to provide such a heat exchanger comprising a tubular member having a plurality of inner tubes bonded in a body of pervious material.
It is a still further object to provide such a heat exchanger which may be employed within a radiator hose of an automobile cooling system.
Additional objects and advantages will become apparout to those skilled in the art from a consideration of the 3 changer of FIGURE 1, taken along the lines II-II thereof,
FIGURE 3 is a longitudinal cross-section of the heat exchanger of FIGURE 1, taken along the lines III-III of FIGURE 2,
FIGURE 4 is a diagrammatic view of a heat exchange medium flowing around a tube of circular cross-section,
FIGURE 5 is a diagrammatic view of a heat exchange medium flowing around a tube of substantially elliptical cross-section,
FIGURE 6 is a view similar to FIGURE 2, showing a second embodiment of the instant heat exchanger, and
FIGURE 7 is a diagrammatic view of the modular concept of the instant invention.
A first embodiment of heat exchanger according to this invention is shown in FIGURE 1, and is designated generally by 10. A first heat exchange medium, for example the medium to be employed in heating or cooling, is introduced into the heat exchanger 10 at one end thereof, as shown by the arrow 11, and exits from the opposite end thereof in the direction of the arrow 12. A second heat exchange medium, for example the medium to be cooled or heated, enters the heat exchanger 10 through any suitable fitting in the direction of the arrow 13, is circulated through the heat exchanger, and exits through a suitable fitting in the direction of the arrow 14. It will be obvious that any desired media might be employed in the instant heat exchanger; for example, the medium introduced at 11 may be water and that introduced at 13 may be oil.
Referring now to FIGURE 2 of the drawings, it may be seen that heat exchanger 10 comprises an outer tube 15 and a plurality of inner tubes 16 and 17. It will be obvious that the tubes 15, 16, 17 may take any desired configuration. However, the tube 15 is shown as being of a circular cross-section, the tubes 16 of substantially elliptical cross-section, and the tubes '17 of a circular crosssection, all for reasons to become evident shortly. Surrounding the inner tubes 16 and 17 and joined to such tubes by a metallic bond is a body of pervious material 18. The pervious body 18 is formed in such a manner, to be discussed hereinafter, that there exists at an upper portion of the heat exchanger 10 a void 19, and at the lower portion thereof a void 20.
As can best be seen in FIGURE 3, communicating through the upper portion of heat exchanger 10 is an inlet fitting 21 which communicates with void 19, and at a lower portion of the heat exchanger there is located an outlet fitting 22 which communicates with void 20. Referring still to FIGURE 3, it may be seen that each of the inner tubes 16 and 17 is secured and sealed at its opposite ends within suitable apertures of two header plates 23 and 24. Header plates 23 and 24 are in turn secured and sealed to the inner periphery of tube 15.
As shown, the heat exchanger 10 may be used in a radiator hose of an automobile cooling system, and accordingly there is no need to seal the ends of the heat exchanger as shown in FIGURE 3. It will be evident that portions of a radiator hose may be merely slipped around the opposite ends of the heat exchanger, and secured in any appropriate fashion, as by standard hose couplings. However, the heat exchanger shown need not be used exclusively Within a hose; by connection of suitable end plates, provision may be made for connection of additional piping means for circulation of the first medium.
In either case, it will be evident that one of the heat exchange media may be circulated longitudinally through the heat exchanger 10. Such a condition is shown in FIGURE 3, wherein the dashed arrows 25 represent the flow of one heat exchange media, for example the water of an automotive cooling system. The second heat exchange medium, for example oil, may be introduced through the inlet fitting 21 and follow the path of the solid arrows 26. Specifically, the second heat exchange medium would enter through inlet fitting 21, flow within the void 19 distributing along the length thereof, through the pervious body 18 around the tubes 16 and 17, collecting in the void 20, thence out through outlet fitting 22 It will be evident that void 19 fonms a distribution manifold for the entering medium, there being less resistance to flow in such an area than in the 'pervious body. After distribution along the entire length of manifold 19, the flow would then necessarily be through the pervious body 18 downward, between and around the tubes 16 and 17. Void 22 would consequently serve as a collection manlfold, the fluid collecting and exiting through outlet 22. Obviously, suitable fittings may be connected to fittings 21 and 22 for connection of appropriate piping of the second medium. Thus, it can be seen that in the instant heat exchanger, the flow of the second heat exchange medium is substantially perpendicular to the flow of the first heat exchange medium, in contrast to heat exchangers presently in use wherein the flow paths of the two media are substantially parallel.
As indicated hereinbefore the inner tubes 16 and 17 may take any desired configuration; however, the configurations shown have been chosen to achieve maxlmum heat exchange results. Specifically, it has been found that tubes having a substantially elliptical cross-section yield advantages not obtainable by tubes of the conventional circular cross-section. Such a cross-section may be obtained by flattening a conventional tube until the tube assumes a nearly rectangular cross-sectional configuration. A tube having such a configuration is desirable for a number of reasons. Firstly, such a configuration presents a large surface area relative to its frontal area. As known in the art, the application in which the heat exchanger is to be used and the allowable pressure drop will dictate the flow through the interior of the tube. This flow will in turn dictate the frontal area of the tube. By forming the tube in the configuration described, an optimum periphery of tube wall is presented for any given frontal area. Thus, this surface area is considerably increased over conventional configurations, for example a tube of circular cross-section.
Additionally, the substantially elliptical configuration achieves desirable results regarding the medium flowing interiorly of the tube. In a tube of, for example, circular cross-section, the heat exchange taking place is inherently greatest in the regions near the periphery of the tube. Accordingly, the medium flowing near the center of the tube performs little heat exchange, and passes through the tube without performing its intended function. However, in a substantially elliptical tube, the amount of medium not taking part in the heat exchange is materially reduced, since a greater portion of the medium is directly adjacent the outer wall of the tube.
Furthermore, when the fiow of the second heat exchange medium is perpendicular to the axis of the tubes, a substantially elliptical tube provides additional advantages. Referring now to FIGURE 4 of the drawings, there is shown diagrammatically a tube T of circular cross-section, through which flows a first heat exchange medium A. Flowing perpendicunlar to the axis of tube T is a second heat exchange medium represented by the arrows B. As shown, the heat exchange medium B will pass around the tube T, performing its heat exchange function, and flow downwardly on toward the next tube. However, as the medium B passes around the tube T, the flow will inherently miss a portion at the lower end of tube T represented by the distance S. In such an area, little if any heat exchange may take place. This area can be substantially reduced by forming the tube in a substantially elliptical configuration. Thus, as seen in FIG- URE 5, the tube T has a first heat exchange medium A flowing therethrough. The second heat exchange medium B flows about the tube T and, due to the reduction in the disturbance of the flow of medium B, the area S is substantially smaller than area S of FIGURE 4. Thus, it,
will be evident that a greater amount of heat exchange takes place at the lower portion of the substantially elliptical tube than with a tube of circular cross-section. In FIGURES 4 and 5, the pervious body has been deleted for the sake of clarity. The presence of such a body would not materially alter the flow characteristics discussed above.
Again in applications where the flow of the second heat exchange medium is perpendicular to the axis of the tubes, substantially elliptical tubes provide a still further advantage. As indicated hereinbefore, the pervious body surrounding the tubes acts as heat exchange fins for the tubes. It is well known in the art that there exists an aptimum fin distance, or optimum fin length, beyond which little heat exchange can take place. Thus, for two tubes of circular cross-section side by side, the distance between corresponding adjacent points of such tubes will of course vary. Thus, if the two closest points of the adjacent tube be the optimum fin distance, then any fin distance in excess of this distance, as for example that distance between the two furthermost spaced points of the adjacent tubes, performs reduced heat exchange. Similarly, if the distance between the two furthermost spaced points of the adjacent tube be the optimum fin distance, then the distance between the two most closely spaced points would be less than the optimum fin distance. However, for adjacent tubes of substantially elliptical cross-section, the distances between adjacent points of the two tubes is more nearly constant, and hence may be more nearly equal to the optimum fin distance throughout.
The above-noted advantages resulting from the use of tubes of a substantially elliptical cross-section yield surprising heat exchange results. Of course, such a tube is less able to withstand high pressures exteriorly than is a tube of circular cross-section. However, in the instant device, it will be recalled that the tubes are joined by a metallic bond within a pervious body. Such a bond holds the walls of the substantially elliptical tubes in tension and increases the stability of such tubes in withstanding high pressures.
Referring now again to FIGURE 2 of the drawings, it will be seen that the particular arrangement of the inner tubes 16 and 17 provides all of the advantages above noted. The substantially elliptical-tubes 16 are so arranged that the distance between corresponding adjacent points of any two adjacent elliptical tubes is very close to the optimum fin distance. The flow of the second heat exchange medium, which has been noted to be from manifold 19 downwardly to manifold 20, is perpendicular to the axis of the tubes 16 and 17. Accordingly, the noted advantages resulting from the substantially elliptical c-ona figuration are also obtained. Obviously, for an outer tube of circular cross-section, which is the most usual form, use of substantially elliptical tubes 16 will necessarily leave some areas of the pervious body 18 which represent a width greater than the optimum fin distance but a height greater than the height of a tube 16. In such an area, tube 17 of a circular cross-section may be employed if so desired, the distance between the periphery of circular tube 17 and that of the adjacent tube 16 being as nearly possible the optimum fin distance.
Considering now the method by which the instant heat exchanger may be produced, it will be evident that the pervious body 18 may be formed about the tubes 16 and 17 in any of the methods indicated hereinbefore. The tubes 16 and 17 may be positioned in the apertures of end plate 23 and 24, and the resulting assembly situated in an appropriate mold. Thereafter, the particles of pervious body may be poured into the mold, with provision having been made for leaving voids 19 and 20. Following any of the metallurgical processes indicated hereinbefore, a metallic bond may be created between the tubes and the particles of the pervious body, as well as between each of the particles of the pervious body. The assembly may then be inspected, and the openings of header plates 23 and 24 through which the tubes pass may be appropriately sealed if such a seal has not been accomplished by the preliminary joining process. The header plates may then be suitably secured within tube 15 and appropriately sealed. Fittings 21 and 22 may be added at any stage of the manufacture, and any (further end fittings added as needed.
Alternatively, the tubes may be positioned within the header plates 23 and 24, the resulting assembly situated within thetu be 15, and supported by an appropriate mold. Portions of one of the header plates may be apertured so that the particles of pervious body may be inserted therethrough and a channel core may be provided. The resulting assembly may then be treated in accordance with any of the foregoing methods to simultaneously create a metallic bond (A) among the particles of the pervious body, (B) between the tubes 16, 17 and the header plates 23 and 24, (C) between the pervious body and each of the tubes 16 and 17, (D) between the pervious body 18 and the header plates 23 and 24, and (E) between the header plates 23 and 24 and the inner periphery of tube 15. Following such treatment, the apertures of the header plates through which the particles of pervious material 18 and core were introduced may be rescaled. As in the first method of manufacture, the fittings 21 and 22 might be added at any stage of the procedure, and any further end fittings could be added after the initial treatment.
A second embodiment of heat exchanger according to this invention is depicted in FIGURE 6, and is designated generally by 110. It will be understood that the exterior appearance of the heat exchanger will be generally similar to that shown in FIGURE 1, and that FIGURE 6 is a cross-sectional view similar to FIGURE 2. The tubes 116 are analogous to the tubes 16 of the first embodiment and, while not shown, it will be evident that the tubes 116 are secured Within the outer tube between header plates similar to plates 23 and 24 of the first embodiment, see FIGURE 3 of the drawings. Similarly, it will be understood that the tubes 116 convey a second heat exchange medium and the outer tube 115 conveys the first heat exchange medium, which is introduced through a suitable inlet 121 and exits through a suitable outlet 122. Again, similar to the first embodiment, a pervious body 118 completely surrounds the tubes 116.
Referring now to the differences between the second embodiment and the first, it may be seen in FIGURE 6 that the pervious body 118 of the second embodiment is so formed as to be rectangular in cross-section, for reasons to become evident shortly. Pervious body 118 is formed about the tubes 116 in any of the methods indicated hereinbefore so as to achieve a metallic bond between (A) the various particles of the pervious body, and (B) between the pervious body and each of the tubes. Additionally, the rectangular body is formed so as to include two non-pervious plates and 131 on opposite side faces of the pervious body 118. Plates 130 and 131 may be of any desired construction; thin sheets of metal have been tested and atound to be satisfactory. Plates 130 and 131 may be joined to the pervious body 118 in any conventional fashion, as by supporting the plates in a suitable fixture during the process-ing of the pervious body 118. At some portion along the longitudinal length of each of the plates 130 and 131 there is formed apertures 132 and .133, respectively.
Thus, the rectangular body 118 with the tubes 116 joined therein, and the plates 130 and 131 joined thereto, may be fabricated as a modular unit apart from the tube 115. Subsequently, the resulting unit may be positioned within a tube 115 and secured therein as by joining lower portions of plates 130 and 131 to the tube wall, as at 134 and 135, as well as securely sealing the periphery of each of the header plates to the interior of tube 115.
Following insertion of the module into tube 115, it will be evident that the space adjacent the upper face of the pervious body 118 forms a manifold 119, analogous to manifold 19 of the first embodiment, and the space below the lower face of the pervious body .118 forms a manifold 120, analogous to manifold 20 of the first embodiment. Thus, as in the first embodiment, the first heat exchange medium entering through inlet 121 distributes longitudinally along manifold 119, is forced through the pervious body 118, collecting in the manifold 120, thence exiting through outlet 122. Referring momentarily to FIGURE 2 of the drawings, a disadvantage of the heat exchanger there shown is that it is highly difiicult to achieve a secure seal between pervious body 18 and the interior of tube in the portion between manifolds 19 and 20. Any space between the pervious body and the Wall becomes a path of least resistance and the first heat exchange medium will flow through such a space and hence bypass the intended route through the pervious body. Referring again to FIGURE 6, such bypass is effectively eliminated in the second embodiment. As noted above, the lower portions of plates 130 and 131 along the full length thereof are effectively sealed to the tube wall 115. Were the upper portions of the plates 130 and 131 also similarly secured, the high pressure on the insides of these plates would force them outward, leaving a space between the plates 130 and 131 and the pervious body 118, resulting in the unfavorable bypass indicated above. Accordingly, the upper portions of plates 130 and 131 are not sealed to the tube 115; instead, they are apertured as at 132 and 133. Portions of the first heat exchange medium, upon initial introduction into the tube 115, will fiow through the apertures 132 and 133 into the spaces between plates 130 and 131 and the adjacent portions of tubes 115, such spaces being referenced by the characters 136 and 137. These spaces form dead areas or pressure equalization chambers to prevent separation of the plates 130 and 131 from pervious body 118. As noted, the first heat exchange medium introduced will flow into the chambers 136 and 137; thereafter, this fluid is trapped within such chambers and performs no heat exchange function. However, the presence of the medium in each of the chambers 136 and 137 equalizes the pressure on opposite sides of each of the plates 130 and 131, the pressure of the first heat exchange medium flowing through the pervious body 118 being substantially the same as that trapped in the chambers 136 and 137.
The modular construction noted above is further advantageous in that construction of heat exchangers of various sizes is materially facilitated. Thus, any number of heat exchange modules similar to that described above may be combined for use in tubes large enough to accommodate, or to require, more of the inner tubes 116. Obviously the modules may be combined in a variety of fashions, that depicted in FIGURE 7 being merely exemplary, where there is shown, on a reduced scale, a larger tube 215. Interiorly of the tube 215 are situated a plurality of modules 216, 217, 218 and 219, depicted diagrammatically for sake of clarity. The modules 216, 217, 218, 219 may be joined together in any suitable fashion, as by welding at the various juxtaposed faces as shown at 220. As was the case when employing only one module, lower portions of the modular assembly which contact the inner face of tube 215 are suitably joined along their entire length, as at 221 and 222. The functioning of the modular assembly will thus be analogous to that discussed above with regard to a single module used alone.
As will be obvious to those skilled in the art, the perpendicular flow of the second heat exchange medium achieved by the instant device, together with the precise positioning of the internal tubes, attains a high degree of heat exchange with a minimum of pressure drop. The precise flow indicated distributes the second medium over the entire pervious structure in a uniform manner over a greatly increased heat exchange surface. The construction of the pervious body, as Well as of the tubes, will be dictated by the contemplated use of the exchanger dependent upon such factors as the thermal conductivity, specific heat, viscosity, and corrosive nature of the fluid, the presence of clogging solids in the fluid, and tolerable pressure drop.
It is to be understood that the invention is not limited to the illustrations described and shown herein which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are are susceptible of modifications of form, size, arrangement of parts and detail or operation, but rather is intended to encompass all such modifications which are within the spirit and scope of the invention as set forth in the appended claims.
What is claimed is:
1. A tubular heat exchanger for circulation of a plurality of heat exchange media, comprising (A) a first tubular member for conveying a first heat exchange medium,
(B) a plurality of second tubular members for conveying a second heat exchange medium, disposed within said first tubular member, said second tubular members having a substantially elliptical cross section, said elliptical cross section having a long dimension, means for directing said second heat exchange medium to one inlet end of said second tubular members, and means for collecting said second heat exchange medium at an opposite, outlet end of said second tubular members, the longitudinal axis of said second tubular members being in parallel relationship to each other and to the longitudinal axis of said first tubular member, the distance spacing adjacent tubes being constant for essentially the entire length of the said long dimension of said elliptical cross section, whereby the optimum fin distance for the said second tubular members is achieved,
(C) a pervious body filling the spaces between adjacent of said second tubular members, and between said second tubular members and said first tubular member, said pervious body being between the said inlet and outlet means of the said second tubular members, and being joined to said second tubular members and to said first tubular member by a metallic bond and comprising:
(1) a first void located between said pervious body and said first tubular member and extending along the full longitudinal length of said pervious body, means for directing said first heat exchange medium only to said first void thereby effecting controlled distribution of said first heat exchange medium through said pervious body in a path between said second tubular members,
(2) a second void located between said pervious body and said first tubular member and extendind along the full longitudinal length of said pervious body for controlled collection of said first heat exchange medium passing through said pervious body,
(3) said pervious body between said first void and second voids thereof being of a cross-section matching the cross-section of said first tubular member,
whereby said first heat exchange medium passes through said first tubular member and between said plurality of second tubular members in a path perpendicular to the longitudinal axis of said second tubular members.
2. A heat exchanger according to claim 1 further characterized in that all the second tubular members have essentially the same cross section, the heat exchanger also including a plurality of third tubular members within said pervious body, said third tubular members being of a circular cross-section with their longitudinal axes in parallel relationship to the longitudinal axes of said second tubular members, said third tubular members being disposed in cross sectional areas of said pervious body adjacent said first conduit where said second tubular members would not fit.
3. A heat exchanger for circulation of a plurality of heat exchange media, comprising (A) a first conduit means for conveying a first heat exchange medium, (B) at least one heat exchange module secured Within said conduit, said module comprising (1) a plurality of tubular conduit means for conveying a second heat exchange medium,
(2) a pervious body surrounding said plurality of tubular conduit means and joined thereto by a metallic bond, said pervious body being of a substantially rectangular cross-section,
(3) a pair of non-pervious plates on opposed side faces of said pervious body, said plates being located Within said first conduit, said plates being parallel to the direction of flow of said first heat exchange medium and parallel to the said plurality of tubular conduit means,
(4) aperture means in said non-pervious plates allowing said first heat exchange medium to pass therethrough, whereby the pressure on opposite sides of each of said plates is substantially equalized,
(C) inlet means in said first conduit means adjacent an upper face of said module, (D) outlet means in said first conduit means adjacent a lower face of said module, whereby said first heat exchange medium passes through said module from an upper face thereof to a lower face thereof, flowing around said tubular conduit means in a direction perpendicular to the longitudinal axes thereof. 4. A heat exchanger according to claim 3 including a plurality of said modules joined together in operative relationship.
5. A heat exchange module for insertion in a conduit adapted to convey a first heat exchange medium, said module comprising (A) a plurality of tubular conduit means for conveying a second heat exchange medium,
(B) a pervious body surrounding said plurality of tubular conduit means and joined thereto by a metallic bond, said pervious body being of a substantially rectangular cross-section,
(C) a pair of non-pervious plates on opposing side faces of, and in intimate contact with, said pervious body, said plates surrounding said tubular conduit means on the two sides of said tubular conduit means which are parallel to the longitudinal axis of said tubular conduit means, and
(D) aperture means in each of said non-pervious plates to allow passage of said first heat exchange medium therethrough, whereby the pressure on opposite sides of each of said plates may be substantially equalized.
6. A heat exchange module according to claim 5 wherein said tubular conduit means are each of a substantially elliptical cross-section and the distances between corresponding adjacent points on the periphery of adjacent tubes are substantially equal.
References Cited by the Examiner UNITED STATES PATENTS 1,840,510 1/1932 Kelley 165-158 2,401,797 6/1946 Rasmussen l65l80 X FOREIGN PATENTS 699,151 10/1953 Great Britain.
ROBERT A. OLEARY, Primary Examiner.
MEYER PERLIN, Examiner.
N, R. WILSON, A. W. DAVIS, Assistant Examiners.