US2274965A - Refrigeration - Google Patents

Description

March 3, 1942. w.|-1. KlTTO 2,274,965

REFRIGERATION Filed March 18, 1938 2 SheerLs-Sheet 1 INVENTOR William [ZKitto ATTORNEY w. H. K|TTO REFRIGERATION Filed March 18, 1938 2 Sheets-Sheet 2 INVENTOR M/illiamIZKitZo ATTORSIEY Patented Mar. 3, 1942 2,274,965 REFRIGERATION William H. mm, Canton, Ohio, assignor at The Hoover Company, North Canton, Ohio, at corporation of Ohio Application March 18, 1938, Serial No. 196,663

12 Claims.

This invention relates to heat exchange apparatus and more particularly to gas heat exchangers specially adapted for .use in absorption refrigerating systems.

Heat exchangers previously constructed have not provided suflicient heat exchange area within the space limitation imposed by domestic refrigerating systems; they have not been designed to insure the necessary turbulence in the gas stream, and they have not been provided with a satisfactory arrangement for insuring proper and continuous tight fitting relationship between the interfitting elements of the heat exchanger or for compensating for manufacturing errors without complicating the entire structure in an impractical manner.

According to this invention, there is provided a heat exchanger which comprises an outer casing of heavy material constructed to withstand a high pressure prevailing within the system and an inner member which is made up of a plurality of interfitting and interconnected light weight sheet metal elements having a high heat conductivity. The inner member of the heat exchanger is constructed and arranged to force the fluid in each of the passes to follow a long tortuous path in which turbulence is induced and in which the fluids are forced repeatedly to wipe and strike the various heat exchange walls of the system. There is also provided a simple takeup device which will insure tight fitting relationship between the various elements in the inner member of the .heat exchanger and will auto-v matically and simply compensate for the minor errors inevitable in mass production manufac- 3 core.

This invention provides a heat exchanger which is simple and easy to manufacture and which is particularly characterized in that a plurality of sub-assemblies may readily and simply be grouped together and placed within the heat exchanger vessel to form the completed apparatus.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic representation of a refrigerating system embodying a heat exchanger constructed in accordance with the invention.

Figure 2 is a partial sectional view on an enlarged scale of one form of the heat exchanger. Figure 3 is an exploded view of the elements constituting each of the sub-assemblies of the inner element of the heat exchanger of Figure 2.

. Figure 4 is a fragmentary sectional view of a modified form of heat exchanger.

Figure 5 is an exploded view of the elements forming the inner sub-assemblies ofthe heat exchanger of Figure 4.

Figure 6 is a fragmentary sectional view of a third modification of the invention.

Figure 7 is a fragmentary sectional view illustrating a detail of the upper end of the heat exchanger of Figure 2.

For purposes of illustration, I have elected to disclose my invention as being applied to a continuous three-fluid absorption refrigerating system; however, it is to be understood that my invention is not limited thereto but may be applied equally well to other types of refrigerating systems and to other systems requiring heat exchange elements.

The refrigerating system disclosed in Figure 1 comprises a boiler B, an analyzer D, a rectifier R, a condenser C, an evaporator E, a gas heat exchanger H, an absorber A, and a circulating fan F driven by an electrical motor M. These elements are suitably connected by various conduits to form a complete refrigerating system including a number of gas and liquid circuits as will be described more fully hereinafter.

The refrigerating system just described is suitably charged with a refrigerant such as ammonia, an absorbent such as water, and pressure equalizing medium, preferably a dense inert gas like nitrogen. v

A suitable source of heat such as a gas burner or an electrical cartridge heater will be provided to heat the boiler B. The source of heat for the boiler and the supply of electrical current to the motor M will be controlled in any desired manner. A preferred control mechanism as illustrated and described in the co-pending application of Curtis C. Coons filed June 16, 1937, Serial No. 148,424. g

The boiler B contains a solution of refrigerant in an absorbent which liberates refrigerant vapor when subjected to heat. Refrigerant vapor generated in the boiler passes upwardly through the analyzer D in counterflow relationship to strong absorption solution flowing downwardly therethrough. Additional refrigerant vapor is generated from the strong solution by the condensation of vapor of absorption solution formed in theboiler. The refrigerant vapor is conducted fromrthe analyzer D into the upper portion of an air-cooled condenser C by a conduit H which includes the air-cooled rectifier R. The rectifier R causes condensation of any vapor' of absorption solution which may pass through the analyzer D.

Weak solution formed in the boiler is withdrawn therefrom into the upper end of an aircooled absorber A through a conduit l2. .It is apparent that the absorber is at an elevation substantially above the liquid level prevailing in the boiler-analyzer system; therefore, it is necessary to elevate the weak solution into the absorber. For this purpose a gas bleed-off conduit I3 is connected between the discharge conduit M of the circulating fan F and the weak solu tion conduit |2 below the liquid level normally prevailing in the boiler-analyzer system whereby the weak solution, is elevated into the absorber by gas-lift action.

counterflow relationship to a mixture of pressure equalizing medium and refrigerant vapor flowing upwardly therethrough. The refrigerant The weak solution; flowsdownwardly through the absorber A in' vapor is absorbed by the weak solution and the heat of absorption is rejected to the surrounding medium by means of the cooling fins on the absorber. The strong solution formed in the absorber is conveyed from the lowerend thereof through aconduit I5 into a solution reservoir l6 and a conduit into the upper portion of the analyzer D. The conduits l2 and I! are in heat exchange relationship as illustrated.

The lean pressure equalizing medium formed in the absorber by the absorption of the refrigerant vapor exits from the upper end thereof through a conduit into the suction inlet of the circulating fan F. The lean pressure equalin any desired manner, preferably by welding.-

The interior construction of the heat exchanger is formed from a plurality of nested subassemblies 33 which are formed of a plurality of individual elements 34, and 36 which are formed, as by stamping, from thin sheet material, preferably having a high heat conductivity.

The element 34 is circular in horizontal cross section except that it is'formed with one straight edge 38. The element 34 is surrounded by a flange 33 which is cylindrical except for the straight portion 38. The flan e 39 joins with an annular flat portion which merges into a conical portion 4| terminating in an upstanding cylindrical collar 42,

"9 element 35 of the assembly 33 is formed V y'disc provided with a straight edge 44 corr ponding to the 34. A plurality of small openings are punched in the plate 35 on'a radius equal to approximately half the total radius of the plate. The central portion of the plate 35, is provided with an offset upwardly bulged portion 46.

The lower element 36 is formed from a disc of light thin sheet material. The disc 36 is provided with an annular flat rim portion 48 provided with a straight edge 49 corresponding to the edges 38 and 44 of the elements 34 and 35, respectively. The flat rim 48 merges into a ,conical portion which terminates in a cylindrical collar element 5|.

izing medium is discharged through the conduit |4 into the outer pass of the gas heat exchanger H. The gas in the outer pass of the heat exchanger H is discharged therefrom into the lower portion of an evaporator E. The evaporator E is shown purely diagrammatically; it may be of any desired construction or form. Preferably the evaporator will include a low temperature freezing portion and a high temperature flnne'd box-cooling portion. medium flows upwardly through the evaporator E in counterflow relationship to liquid refrigerant supplied thereto through the conduit 2| which connects to the lower portion of the aircooled condenser C. A small dam 22 prevents the liquid refrigerant from flowing downwardly into the gas heat exchanger through the rich gas conduit 24. The refrigerant evaporates intothe pressure equalizing medium in the evaporator. to produce refrigeration and the resulting rich mixture is discharged from the upper portion of the evaporator through a conduit 24 into the inner. pass of the gas heat exchanger H. The rich mixture is discharged from the inner pass of the gas heat exchanger H into the lower end of the absorber A through a conduit 25'.

The refrigerating system 'just described is an example only; the system may be of any desired construction or form.

Referring now to Figures 1 to 3, the heat ex,- changer will be described in detail. \The heat exchanger H comprises an outer vessel 3| constructed of heavy material capable of withstandment 32 which receives the rich gas conduit 25. The elements 25, 3| and 32 are secured together The pressure equalizing The collars 42 and 5| of the elements 34 and 36, respectively, are displaced from the centers of the conical portions 4| and 58, respectively; however, these elements are located centrally of the circles of the flanges 39 and 48.

The elements 34, 35 and 36 are assembled as follows: The element 35 is inserted in the element 34 with the portions 44 and 38 thereof, respectively, registering and the bulge portion 46 projecting upwardly toward the collar 42. The

' element 36 is then inserted within the flange 39 with the straight edges 38 and 49 registering whereby the element 35 is secured between the horizontal flanges 48 and 48 of the elements 36 and 34, respectively. The flange portion 39 is then pressed down over the outer portion of the flange 48 thereby securing the elements 34, 35 and 36 in rigid fluid tight relationship.

The assemblies 33 are joined together by interfltting the collar 5| of one. element 33 into the collar 42 of the subjacent element 33. Adjacent assemblies 33 are positioned with their straight edge portions 52, degrees apart.

The group of sub-assemblies 33 is then inserted into the cylindrical casing 3|. The' dimensions and arrangements of the elements 33 are such that the outer portions of the flanges 39 abut the innerwall of the casing 3| in a substantially fluid tight manner throughout their circumference except for the relatively small spring 62 bears against the header 32 and a spring retaining plate 63 which is provided with a collar 84 slidably fitting within the collar 68. The central portion of the plate 63 is provided with an opening which receives the collar 5| of the lowest element 36 of the inner member of the gas heat exchanger. The rich gas discharge portion 38 of the element I of the spring 62.

conduit 25 opens into the space within the interfltting collars 60 and 84.

Figure 7 illustrates the manner in which the top portion of the gas heat exchanger is formed. The cylindrical casing 3! is provided with a dome-shaped top 65 which receives the rich gas conduit 24. A short cylinder 81 is secured in the top portion of the casing 3| in any suitable manner as by welding. The collar 42 ofthe topmost assembly 33 receives a downwardly extending flange 68 defining a central opening in an otherwise imperforate end plate 68 which is adapted to abut the lower portion of the cylindrical section 61. The lean gas evaporator connection opens into the casing 31 below the plate 59. The plate 68 defines the end position of the inner element of the gas heat exchanger and is urged against the element 51 by the bias It is clear from Figure 7' that therich gas discharges into the dome 6S and then passes downwardly into the inner element of the gas heat exchanger whereas the lean gas passing upwardly through the gas heat exchanger exists into the evaporator without mixing with the rich gas.

The heat exchanger just described is assembled in the'following manner. The sub-assemblies 33 are formed as previously described. The sub-assemblies 33 are then joined together with each collar 42 receiving the superposed collar and the top collar 42 receiving the flange 68 of the end plate 69. This assembly is then placed within the casing 3| from the bottom thereof after which the plate 63 is slipped over the lowest collar 5|, the spring 62 is placed within the collar 84 and the end plate 32 is then assem bled in the casing 31.

The spring 62 serves to insure tight fitting relationship between the interfitting heat exchanger sub-assemblies thereby maintaining a gas-tight seal therebetween and to compensate for inaccuracies which may occur in manufacture and assembly.

It is apparent that the gas stream passing upwardly around the inner member of the gas heat exchanger passes back and forth across the sub-assemblies 33, and, as it does so, it continually wipes and scrubs the walls of the ele- V mentsj and 36 as well as the inter-fitting collars.

Thegas stream passing downwardly through the inner member of the gas heat exchanger passes through the collar 5|, scrubs the inside walls of the elements 3|, passes through the openings in the elements 35, and then scrubs the inside walls of the elements 38. Efiicient heat exchange between the two gas streams is assured by reason of the fact that they travel in opposite directions along opposite sides of thin heat conducting walls to secure the advantage of counterfiow relationship. The upstanding bulges 46 a e scrubbed by the gas stream passing downwardly with relation thereto and also serve to direct the gas stream into the openings 45. .The heat taken up by the elements 35 is transmitted therethrough directly to the rims l0 and 88 of the elements 34 and 36, respectively, which elements are directly exposed to and are scrubbtd by the outer gas stream.

Referring now to Figures 4 and 5, there is disclosed a modification of the invention which will be described in detail. Parts of this inventi n are identical with those previously described and are given the same reference characters primed. The inner member of this gas heat exchanger is constructed of a plurality of interfltting subassemblies 10 comprising the elements II, 80, BI and 83. An exploded view of the sub-assemblies I0 is shown in Figure 5 and will now be described. The upper element of the sub-assembly is a plate H which is provided with a straight edge 12, and a central opening defined by an upstanding collar 13 which terminates in an inwardly directed flange 14. The next lower element 88 of the sub-assembly I0 is formed from a, sheet metal disc and is stamped to form a cylindrical flange l5 joining with an annular plate portion 78 which merges into a conical portion 18 terminating in an upstanding cylindrical collar 19 surrounding a central opening. The next lower element of the sub-assembly 10 is formed from a cylindrical disc 8! which is provided with a plurality of struck-up tongues- 82, alternate tongues being struck in opposite directions. The lowest member 83 of the subassembly comprises a sheet metal disc which is stamped to form an outer annular flange 84 which merges into a downwardly directed conical portion 85 terminating in a cylindrical collar 86 which defines a central bottom opening.

The constituents of the elements 10 are assembled as follows: The element H is mounted on the element 80 with the flange I4 resting uponthe upper end of the collar 19. The element 81 is placed in the downwardly converging conical portion 85 of the element 83 with the downwardly struck tongues 82 resting on said conical portion. The-flange 84 of the element 83 is then placed within the cylindrical collar 15 of the element 80 and resting upon the annular portion 18 thereof.

The cylindrical flange i5 is then turned backwardly around the annular flange 84 thereby securing the elements of the sub-assemblies in rigid gas-tight relationship. The struck-up tongues 82 bear against the conical portions 18 and 85 thereby spacing the plate 8| approximately equal distances from those portions and forming a gas pass between the cones I8 and 85 around the edges of the plate 8|.

The sub-assemblies Ill are joined together with the collars 19 extending upwardly and the collars 86 extending downwardly. The collars 19 of each sub-assembly receive the downwardly directed collar 86 of the superposed sub-assembly with the flange 14 of the disc ,Il clamped between the upper edges of the collar 19 and the conical portion 85 of the superposed assembly. The heat exchanger is assembled with the straight edge v portions 12 of the discs 1| positioned approximately degrees apart.

The upper portion of the heat exchangerris constructed in the manner illustrated in Fi ure '7; that is, the collar 19 will receive the flange 68 of the plate 69.. The spring take-up structure is identical with that described in connection with Figures 1 to 3 and functions in exactly the same fashion. The plate 83" receives the lowest collar 88 corresponding to the collar 5| in Figures 1 to 3. I

The heat exchanger illustrated in Figures 4 and 5 is assembled as follows: The sub-assemblies are first made up and are then assembled to-- in Figures 4 rection around or across the flattened edge 12 of the element ii and then backwardly in the opposite direction across the surfaces of the next higher sub-assembly Hi. It is apparentthat the outer gas stream scrubs and wipes the outer walls of the sub-assemblies it and the plates H which are in heat exchange relationship with the collars 19. The gas flowing in the inner path of the heat exchanger is caused to wipe the inner walls of the sub-assembly ill by the central plate 8| which provides only a restricted opening adjacent the point of connection between the flanges B4 and 76. By reason of this construction, emcient heat exchange is assured because of the fact that the gas streams between which heat is to be exchanged are caused to flow through long tortuous paths in intimate contact with thin metallic walls having a high heat conductivity.

In Figure 6 there is disclosed a third modification of the invention embodying features found in each of the modifications heretofore described. The end assemblies of the heat exchanger shown in Figure 6 are identical with those shown in Figures 2 and 7 and will not be described in detail.

The heat exchanger shown in Figure 6 comprises cylindrical casing 3:! identical with those heretofore described and aplurality of interfitting sub-assemblies 95 forming the inner member of the gas heat exchanger. Each sub-assembly 90 comprises an upper element 59' which is identical with the element 80 heretofore described, a

central element 35' which is identical with the element 35 heretofore described except that the bulge 48? is in the center of the element and the straight edge 44 is not provided. The bottom element 83' of the sub-assembly 90 is identical with the element 83 heretofore described. The elements 80', 35' and 83 are assembled in the manner described in connection with the elements 34, 35 and 3B.

The sub-assemblies 90 are joined together with the collars 79' receiving the collars 86' of the superposed sub-assemblies.

Thecollars 19' receive gas guiding plates 9| on the outer portions thereofprovided with collars 92 embracing the collars 19' and having straight edge portions 93 carresponding to the straight edge portions" of the plate H. The inner member of'this heat exchanger is assembled in a manner which is apparent -from the description preceding, with the straight edge portions 93 positioned 180 degrees apart whereby the gas is caused to travel in a path such as that described in connection with Figures 4' and 5.

The heat exchangers above described are read-. ily formed by the simple process of punching or stamping the elements thereof from flat strips of thin light weight sheet metal preferably having a relatively high heat conductivity. The elements so stamped are assembled as described above into a plurality of sub-assemblies which in turn are assembled as above described to form a complete inner member of the gas heat exchanger which is then inserted into a cylindrical casing forming the outer wall 'of the heat exchanger. In eachform of the invention a spring take-up device is provided which insures that the varioussub-assemblies shall not slip relative to one another, come apart, or permit the Joints to open and leak. The spring take-up device also holds the inner assembly rigidly in proper position and compensates for any errors which may occur in manufacture or assembly.

The herein disclosed heat exchangers provide a pair offluid paths of constantly changing contour and cross-sectional area whereby the fluid streams travel at varying velocities and with a high turbulence. The fluid streams are constantly wiping and impingingupon the heat transfer walls of the inner members of the heat exchanger while travelling in opposite directions.

The long tortuous fluid paths, the extensive thin heat exchange walls in the turbulent fluid streams, and the counterfiow of the fluid streams produce a highly efiicient heat exchanger.

The resilient mounting mechanism constantly urges the various plate elements of the inner member of the heat exchanger into intimate heat exchange and gas tight relationship. In addition the resilient mounting mechanism will compensate for manufacturing errors. Preferably the resilient mounting mechanism is so designed that it will compensate for the omission of one of the sub-assemblies of the inner element of the heat exchanger.

While I have illustrated and described three embodiments of my invention, it is to be understood that my invention is not limited thereto but that changes in the form and construction and arrangement of parts may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. Absorption refrigeration apparatus comprising apressure equalizing medium circuit including an evaporator and an absorber, a solution circuit including a boiler and said absorber, power driven means for circulating a pressure equalizing medium through said circuit, a gas heat exchanger in said pressure equalizing medium circuit, characterized by the fact that said gas heat exchanger includes another sealed casing member, a plurality of slidably connected elements forming a heat transfer and gas separating wall within said casing member, and means for resiliently urging said slidably connected elements together.

2. Refrigerating apparatus comprising an inert system pressure, and forming a heat transfer and gasstream separating wall, said inner'member comprising a plurality of conduit forming elements, each of said. conduit forming elements having an axially extending connecting collar, 8. body portion, and anattaching flange, the attaching flanges of pairs of said elements being secured together, the connecting collar of each of saidelements being telescopically engaged to the connecting collar of an adjacent conduit element, a rigid support for said inner member in one end of said outer member, and a. spring mounted between the opposite end of said inner member and said casing whereby unequal expension of said inner and outer members does not cause separation or crushing of the component parts of said inner member.

3. Heat transfer apparatus comprising a housing member, a plurality of nested elements mounted within said housing and forming a heat transfer and flow directing wall, each of said nested elements comprising a pair of chamber forming members, each of said chamber forming members comprising an axially extending connecting conduitand a flared body portion, the flared body portions of each pair of chamber forming members being joined, and the axially extending conduits of adjacent nested elements being telescoped, a spring urging said heat transfer and flow directing wall against one end of said housing member whereby unequal expansion and contraction of said housing member and said wall does not produce a significant change in the pressure with which said nested elements are urged together.

4. Heat exchange apparatus comprising a casing, a member within said casing forming a heat transfer element, said element including a plurality of interfltting parts, each of said interfltting parts comprising a pair of dished elements secured together at their edges, and fluid directing elements positioned centrally between each pair of said dished elements, said fluid directing elements being clamped between said dished elements and in heat transfer relationship therewith, and a resilient spring bearing against one end of said element and urging the same against one end of said casing whereby said interfitting parts are maintained in tight fltting nested relationship under conditions produced by expansion I and contraction thereof.

5. Heat transfer apparatus comprising a housing member, a plurality of nested elements mounted within said housing and forming a heat transfer and flow directing wall, each of said nested elements comprising a pair of chamber forming members provided with axially extending connecting conduits and flared body portions, and a rim portion, said rim portions being flat, the chamber forming members of each of said nested elements being positioned with-. the flared body portions extending in opposite directions, the rims of said chamber forming members being 'shaped to engage the inner wall of said casing continuously except for a portion forming a fluid pass with the inner wall of said casing, the fluid pass forming portions of adjacent nested elements'being angularly displaced.

6. Heat exchange apparatus comprising a casing, a member within said casing forming a heat transfer element, said element including a plurality of nested elements, and fluid directing plates mounted on and in heat exchange relationship with the nested portions of said nested elements, said plates being constructed and arranged to direct fluid flowing between said casing and nested elements across each of said nested elements in a direction opposite to itsdirection of flow across contiguous nested elements.

'7. Heat transfer apparatus comprising a housing member; a plurality of nested elements mounted within said housing and forming a heat transfer and flow directing wall, each of said nested elements comprising a pair of chamber forming members provided with axially extending connecting conduits and flared body portions, the axially extending collars of adjacent nested elements being telescoped and fluid guiding plates mounted upon the telescoped collars of the nested elements.

8. A heat exchanger comprising an outer vessel of heavy material, and an inner conduit of light prising a plurality of pairs of pocket forming elements, each of said pocket forming elements comprising an axially extending conduit joined to a flared body portion terminating in an annulus, the annuli of each pair of pocket forming elements being secured together, said axially extending conduits being nested, and resilient means urging said pairs of pocket forming elements into nested relationship.

9. A heat transfer device comprising an outer member, an inner member forming a heat transfer and gas stream separating wall, said inner member comprising a plurality of conduit forming elements, each of said conduit forming elements having an axially extending connecting collar; 2. body portion, and an attaching flange,

the attaching flanges of pairs of said elements being secured together, the connecting collar of each of said elements being telescopically engaged to the connecting collar of an adjacent conduit element, a rigid support for said inner member in one end of said outer member, and a spring mounted between the opposite end of said inner member and said casing whereby unequal expansion of said inner and outer members does not cause separation or crushing of the component parts of'said inner member.

10. Heat transfer apparatus comprising a casing element, a fluid pass defining wall within' said casing, said fluid pass' defining wall comprising a plurality of slidably connected inter-fitting parts abutting one end of said casing element, and a resilient element arranged between said wall element and the other end of said casing element to urge said wall element against said one end of said casing element and to prevent separation or crushing of said slidably connected interfltting parts due to unequal expansion and contraction of said casing element and said wall element.

11. Heat transfer apparatus comprising an outer fluid confining element, an inner fluid confining element cooperating with said outer element to form a pair of fluid flow paths, said inner element being constructed from a plurality of parts slidably nested together, an abutment in one end of said outer element against which one end of said irmer element abuts, an abutment in the other end of said outer element, an abutment member on the other end of said inner element, and an expansible and compressible element interposed between said last mentioned abutments and urging the same apart to prevent crushing and separation of said slidably nested parts due to unequal expansion and contraction of said inner and outer elements.

12. Heat exchange apparatus comprising a casing, a member within said casing cooperating therewith to form a plurality of paths of flow for fluids between which heat is to be exchanged, said member being constructed of a plurality of light weight sheet metal parts slidably connected together, a flxed abutment at one end of said casing against which one end of said element bears, and resilient means bearing against the other end of said casing and the other end of said element to urge said element against said abutment and the slidably connected parts of said element together with a substantially constant force and to compensate the apparatus for unequal expansion and contraction of said casing and said element. 7

WILLIAM H. KITTO.

weight sheet material, said inner conduit com-

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