US 3256930 A
Description (OCR text may contain errors)
June 21, 1966 P. G. NoRBAcK 3,256,930
HEAT EXCHANGER Filed Nov. 22. 1960 2 Sheets-Sheet 2 4 INVENTOR.
United States Patent 3,256,930 HEAT EXCHANGER Per Gunnar Norbiick, 33 Askrikevagen, Lidingo, Sweden Filed Nov. 22, 1960, Ser. No. 70,946 Claims priority, application Sweden, Nov. 24, 1959, 1 069/59 6 Claims. c1. 165-46) This invention relates to heat exchangers. More particularly this invention relates to heat exchangers for two fluids, one of which is a liquid and the other a gas, the fluids being separated from one antion while at the same time the requirements for favorable flow conditions with regard to resistance to flow and heat transfer are not neglected.
A further object of the invention is to provide a heat exchanger of the type under consideration which has light weight and nevertheless a high capacity of heat transfer per unit volume.
Further objects and advantages of the invention will become apparent from the following description, considered in connection with the accompanying drawings, which form part of this specification and of which:
FIG. 1 is a perspective and partially sectional view of a heat exchanger constructed according to the invention and intended for air conditioning of a room or enclosure.
FIG. 2 is also a perspective and partially sectional view of a portion of the heat exchanger shown in FIG. 1 but on an enlarged scale.
Referring to the drawings reference numeral 10 denote a wall which has an opening, into-which acasing 12 of a multi-layer heat exchanger is inserted. The casing has a lower intake 14 for a gaseous fluid such as fresh air, for example, which after passage through the layers of the exchanger is introduced into the room or enclosure to be conditioned through an opening controlled by a damper 16. Water of a higher temperature than that prevailing in the room or enclosure is introduced into the apparatus through a pipe 18 and returned to a central heating device through another pipe 20. The air may' also be assumed to circulate within one individual enclosure. or a group of enclosures. If cooling is intended,
a cooling agent such as cold water, for example, is circulated through the pipes 18 and 20.
The body of the exchanger comprises two groups of layers or partitions, one of which is constituted by foils or sheets 22, 24 of a material which is not self-sustaining but is pliable and possibly even easily extensible. vA particularly suited material may be of some kind of plas tic material such as polyethelene. The two sheets 22, 24 are cemented together around their edges along a welding or bonding joint 26 so as to form a closed jacket 27 having the shape of a bag, sack or similar pliable container. The jacket may be subdivided into a zigzagshaped fluid passage by means of strips or seams 28 extending from the upper edge portion of the jacket and terminating in slightly spaced relationship from the lower edge portion thereof and by .strips or seams 30 which extend from the lower edge portion and terminate in slightly spaced relationship from the upper edge portion of the jacket. Said strips or seams may be formed by welding or gluing the sheets together. The upper ends 3,256,930 Patented June 21, 1966 "ice of the strips 28 are slightly spaced from the joint 68 in order to render possible that air present in the jacket when the operation of the exchanger is started or gases penetrating into the jacket during the later operation can be removed and thus are deprived of any opportunity of forming plugs barring the flow of the liquid fluid.
The other group of layers or partitions is constituted by foils or thin sheets of a more rigid material such as metal and is alternately disposed between the jackets 27. In the embodiment shown in the drawings the second group of layers is constituted by units 32 each of which consists of three plane sheets 34, 36, 3S and two corrugated sheets 40 and 42 disposed therebetween, all sheets being made of aluminum and having a thickness of hundredths or tenths of a millimeter such as between 0.025 and 0.2 mm. The individual foils or sheets of the unit under consideration are secured to one another by means of a bonding agent which in its simplest form may be a water glass. The bonding agent may also be an organic gluing agent such as a urea resin glue or some other curable and preferably water-soluble glue. The ridges of the corrugations of the corrugated sheets 40 and 42 extend transversally to the strips or seams 28, 30 in the other group of layers. The units or packings 32 form channelshaped interspaces which penetrate from one edge to an opposite edge of the unit and are open at both ends to the surrounding air.
'The jackets 27 are intended ,to permit circulation of the liquid fluid for which reason their inner interspaces 44 are in communication with'a common distribution channel or header 46 and a common collecting channel 48. Said channels are suitably located at two diametrically opposite corners of the rectangular sheets of pliable material which may be formed with lugs or loops 50. The channel is constituted by tubular members 52 provided with circumferentially spaced holes 54 communicating with the interspaces 44. Clampedbetween the tubular members having shoulders suited to one another are the sheets adjacent one another of two jackets 27, as will be seen from FIG. 2. The tubular members thus have a length equal to the total space of one jacket and one metal sheet unit 32 which implies that the sheets 22, 24 are extended to form a bulb 56 around the tubular memher.
and 48, respectively, will communicate with the individual interspaces 44 between the sheets 22, 24 while said interspaces otherwise are sealed from other parts of the device.
The pipes 18 and 20 are connected each to its respective 'channel by means of suitable screw joints 58 and 60, and
interconnecting bars (not shown) which extend through said channels and have smaller diameter than that of the channels.
The liquid fluid, in the embodiment shown assumed to be water, is introduced into the upper channel 46 and flows thereafter through the interspaces 44 upwards and downwards along a zigzag path between the strips or seams 26, 30 to the collecting channel 48. Simultaneously, the gaseous fluid which in the embodiment shown is assumed to be air, is caused to pass through the channels of the units 32 in the direction of the arrow 62, if desired by means of a fan (not shown). The two fluids will thus flow through the device in cross-current relationship, which in itself results in a more effective heat transfer between the fluids. This transfer is improved further by the thin-walled partitions and by the fact that the sheets 22, 24 due to the inner water pressure, will adjust themselves closely to the outer sheets of the units 32. It is easily understood that the various groups of sheets in the heat exchanger need not be made with any particular precision because the flexible or pliable plastic material adapts itself to the relatively more rigid aluminum The edge joint 26 passes around the lugs 50 as indicated at 26 in FIG. 2. In this way the channels 46 sheets. Within one and the same .unit 32 the outermost sheets 34 and 38 are in direct contact with the adjacent plastic sheets 22 and 24, respectively, while a heat transfer from or to the interior sheets of the units must be eflected through said outermost sheets. The heat which thus is to be transferred from the Water in the interspaces 44 to the air passing through the channels formed by the corrugations on either side of the middle sheet 36 must pass through a plurality of sheets. As aluminum is an extremely good heat conductor, such heat transfer is effected with a highly satisfactory yield. With a spacing between the plane sheets in the units 32 of a magnitude between 1.5 to 4 or 6 millimeters, high heat transfer eflicients between the sheets and the gaseous fluid may be attained even if the flow of the latter is laminary. The width of the interspaces 44 may be between 1 and 2 to 5 millimeters.
It will be easily understood from the preceding description that the total flow area of the interspaces for the air is greater than that of the interspaces for the water with the consequent result that for a predetermined volume of air the flow thereof may be kept at low, suitable velocities. The available heat transfer surface can be increased with consequent increase of the heat transfer coefficient by subdividing the spaces between the plastic jackets by a plurality of closely spaced sheets such as 34, 36 and 38 between which the metal units 40 are arranged. This makes it possible to reduce the dimensions of the heat exchanger in the direction of flow of the fluids.
The gaseous fluid passing through the heat exchanger may contain a condensable medium such as water vapor carried in an air stream. If the air is cooled down condensate is deposited on the walls of the layers in the units 32. On the other hand, an absorbing liquid such as a solution of lithium chloride may be introduced into the air channels for the removal of absorbable constituents present in the gas. In such cases the ridges of the corrugations may be positioned vertically so as to allow the liquid to run down from the channels of the unit due to gravity. At the lower end of the unit means may be provided to allow a draining while the channels 'are kept open for the passage of the gas as is disclosed in the Patent No. 2,809,818, granted October 15, 1957 to Carl Georg Munters to which specification reference is made for a more detailed description. The invention may also be applied with advantage to an evaporative cooling device. For example, the liquid such as the water in the pliable jackets 27 may be cooled by allowing the water to evaporate from the surfaces of the units 32 which are swept over by the air. The evaporated water is fed into the channels of the unit 32 by means of a sprayer. In such cases where a liquid medium is present in the gas or air interspace, it may be advantageous to provide the surfaces with a liquid adsorbing surface layer or to treat said surfaces so as to become liquid adsorptive.
While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for purpose of illustration only, and
' forming between the interspaces partitions, each partition comprising at least two sheets, the sheets of one partition being more pliable than the other, the more pliable sheets bounding the liquid passageways so that the sheets on the liquid side of the partitions will accommodate themselves under pressure to the shape of the sheets on the gas side of the partitions, the sheets on the gas side being arranged in such a manner to isolate the gas from contact with the flexible sheets.
2. In a heat exchanger according to claim 1, wherein the sheets bounding the interspaces for the liquid passageways are not self-sustaining and are composed of pliable plastic material.
3. In a heat exchanger according to claim 2 wherein the sheets consisting of a pliable material forming closed jackets are connected to a distributing channel and a collecting channel, which channels are formed by tubular members of a self-sustaining material and disposed in rows one behind and fitting to the other.
4. In a heat exchanger according to claim 3, wherein the tubular members have a length surpassing the width .of the interspaces of the liquid passageway, the pliable sheets being in a sealing manner clamped between the tubular members and in a bulbous manner drawn around said members.
5. In a heat exchanger according to claim 1, the interspaces between the partitions of the liquid passageways being subdivided by joining means into a plurality of relatively broad passages.
6. In a heat exchanger according to claim 5, said broad passages being interconnected in series.
References Cited by the Examiner UNITED STATES PATENTS ROBERT A. OLEARY, Primary Examiner.
HERBERT L. MARTIN, ALDEN D. STEWART, PERCY L. PATRICK, CHARLES SUKALO, FREDERICK L. MATTESON, JR., Examiners.
T. W. STREULE, Assistant Examiner.