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Publication numberUS2668692 A
Publication typeGrant
Publication dateFeb 9, 1954
Filing dateOct 19, 1950
Priority dateOct 19, 1950
Publication numberUS 2668692 A, US 2668692A, US-A-2668692, US2668692 A, US2668692A
InventorsHammell Kemper M
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Heat exchanger
US 2668692 A
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Description  (OCR text may contain errors)

Feb. 9, 1954 K. M. HAMMELL 2,668,

HEAT EXCHANGER Filed Oct. 19, 1950 2 Sheets-Sheet l INVENTOR. Kemper M Hammell Feb. 9, 1954 K. M. HAMMELL HEAT EXCHANGER 2 Sheets-Sheet 2 Filed 001.. 19, 1950 INVENTOR. Kemper M. Hammell Patented Feb. 9, 1954 HEAT EXCHANGER Kemper M. Hammell, Harrisburg, Pa., assignor to General Electric Company, a corporation of New York Application October 19, 1950, Serial No. 191,010

Claims. 1

The present invention relates to heat exchangers and more particularly to heat exchangers that are especially constructed to serve commonly as the condensing units in refrigerating systems and as the water heating units in hot water storage and supply systems employed in heat pump arrangements. j It is the general object of the present invention to provide a heat exchanger of improved and simplified construction and arrangement that is efficient and economical in operation.

Another object of the invention is to provide a heat exchanger comprising an improved arrangement for positioning a conduit in a chamber defined by surrounding walls so as to obtain good "heat transfer between a first fluid in the chamber and a second fluid in the conduit and to obtain poor heat transfer between the conduit and the surrounding walls. A further object of the invention is to provide 'a heat exchanger of the character noted that embodies an improved arrangement for mounting the condenser conduit in the water chamber so ,as' to promote efficient heat exchange between the refrigerant in the condenser conduit and the water in the water chamber and so as to retard heat exchange between the condenser conduit and the surrounding walls defining the water chamber. Further features of the invention pertain to the particular arrangement of the elements of the heat exchanger, whereby the above-outlined and additional operating features thereof are attained. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in .connection with the accompanying drawings, in which Figure 1 is a plan view, partly broken away, of a heat exchanger embodying the present invention; Fig. 2 is a fragmentary side elevational view of the heat exchanger, taken principally along the line 2-2 in Fig. 1; Fig. 3 is an enlarged fragmentary perspective view of .the heat exchanger shown in Figs. 1 and 2; Fig. 4 .is a plan view, partly broken away, of a modified ,form of the heater exchanger embodying the present invention; Fig. 5 is a fragmentary side Ielevational view of the heat exchanger, taken Iprincipally along the line 5-5 in Fig. 4; and Fig. 6 is an enlarged fragmentary perspective view of the heat exchanger shown in Figs. 4 and 5. Referring now more particularly to Figs. 1 to 3, inclusive, of the drawings, there is illustrated a heat exchanger It embodying the features of the present invention and comprising an inner substantially cup-shaped member I I provided with a tubular side wall l2 and a convex bottom wall l3, and an outer substantially cup-shaped member I4 provided with a tubular side wall l5 and a convex bottom wall Ifi. A first outwardly extending substantially annular flange or ring I! is secured to the upper end of the side wall 12 in surrounding relation therewith and adjacent to the open end thereof; and a second outwardly extending substantially annular flange or ring [8 is secured to the upper end of the side wall 1'5 in surrounding relation therewith and adjacent to the open end thereof. The inner member I I and the outer member M are arranged in nested relation so that the side walls l2 and I5, as well as the bottom walls l3 and I6 are disposed in spaced-apart relation defining a substantially cup-shaped chamber [9 therebetween, the flange H overlying the flange l8 and closing the open end of the chamber IS. A substantially annular sealing gasket 20 is arranged between the adjacent surfaces of the flanges l1 and I8; and the flanges I! and I8 are secured together in fluid-tight relation by an arrangement including an annular series of bolts 2| extending through aligned holes formed in the flanges l1 and I8 and cooperating nuts 22.

' A substantially centrally disposed inwardly extruded fixture or spud 23 is formed in the bottom wall l6 and receives a cooperating threaded inlet conduit 24 arranged to supply a first fluid into the lower portion of the chamber I9 between the bottom walls I6 and I3. Similarly a substantially centrally disposed inwardly extruded fixture or spud 25 is formed in the bottom wall 13 and receives a cooperating threaded plug 26. An opening is formed in the inner portion of the flange l1 and carries a substantially L-shaped fixture 21 constituting an outlet conduit for the first fluid in the chamber 19. Thus it will be understood that the first fluid is admitted into the lower portion of the chamber l9 via the inlet conduit 24 and is withdrawn from the upper portion of the chamber l9 via the outlet conduit 21.

Arranged within the chamber I9 is a substan- 'tially helical conduit 28 that is preferably in the form of a continuous tube having a substantially oval cross-section that may be produced by flattening of the tube from an initial substantially circular cross-section. The conduit 28 extends continuously in the form of a helix from a position just below the flange l8 to a position just above the bottom wall IS, the conduit 28 being 3 arranged throughout its length in spaced-apart relation with respect to the side walls i2 and I5. The upper inlet end of the conduit 28 is provided with an upwardly projecting inlet connector 29 arranged to supply a second fluid into the upper portion of the conduit 28; and the lower outlet end of the conduit 28 is provided with an inwardly projecting outlet connector 3c. The inlet connector 29 projects through an opening 3| formed in the inner portion of the flange l1 and is removably sealed in place by a pack-v ing gland 32; while the outlet connector 33 projects through an opening formed in the lower"- portion of the side wall l2 and is rigidly secured in place by welding, or the like, indicated at:

33. Also the inner end of the outlet connector cavity of the member I I.

upper end of the conduit 28 via the inlet connector 29 and is withdrawn from the lower end of the conduit 28 via the outlet connector 30', the elbow 34 and the riser conduit 35.

The conduit 28 is positioned within the chamber 19 by an arrangement including inner and outer substantially tubular corrugated sheet structures 36 and 31. More particularly the structure 36 is arranged between and in contact with the side wall I2 and the conduit 28; while the structure 37 is arranged between and in contact with the side wall I and the conduit 23. Specifically in the structure 36, the flutes 38 of the corrugations terminate in rather sharp peaks 39 engaging the adjacent side wall [2, and in rather fiat plateaus 4t engaging the convolutions of the conduit 28; whereby the area. of con.- tact between the structure 36 and the conduit 28 is considerably greater-than the area of contact between the structure 36 and the side wall 12 so that in efiect the structure 36 is arranged in good heat-conducting relation with the conduit 28 and in poor heat-conducting relation with the side wall 12. Similarly in the structure 37, the flutes 4| of the corrugations terminate, in rather sharp peaks 42 engaging the adjacent side wall !5,.and in rather fiat plateaus43 engaging the 'COIlVOllI': tions of. the conduit 28; whereby the area of contact between the structure 31 and the conduit 28 is considerably greater than the areaof contact between the structure 3'! and .theside wall l5 so that in effect the structure 3.? is: arrangedin good heat-conducting relation with the conduit 28' and in poor heat-conductingrelation with the side wall [5.

4 frigerating system and as the water heating unit in a hot water storage and supply system in a heat pump arrangement. When the heat exchanger H! is employed for the purpose noted, the compressed gaseous refrigerant from the compressor of the refrigeratingmachinery is admitted via the inlet connector 29 into the upper end of the conduit 23, and passes downwardly through the convolutions of the; conduit 28 toward the outlet connector 30. 7 Initially the compressed gaseous refrigerant entering the inlet connector 29 contains considerable super heat which is extracted therefrom in the upper por- In; view of the foregoing, it will be understood Moreover the structure 36 with the sidewall If: to define upstanding chane nels 45 therebetween accommodating the passage therethrough of the first fluid in the chamber l9; Finally the structures 36 and 31 cooperate with each other to define upstanding channels 66 therebetween accommodating the passage therethrough and about the convolutions of the conduit 28 of the first fluid inthe chamber 19.

The heat exchanger I0 is admirably suited for use commonly as the condensing unit in a retion of the conduit 28 so that the compressed ,qgaseous, refrigerant is condensed in the midportion of the conduit 23, whereby, the refrigerant is liquifiedv and accumulates in the lower portion of the conduit 28. The liquid refrigerant accumulating in the lower portion of the conduit 28 is sub-cooled therein and is then discharged via the, outlet connector 30, the elbow 3t, and the riser conduit into a suitable receiver, or. the like, provided in the refrigerating machinenv. Of course the liquid refrigerant is ultimately ex.- panded through an expansion valve, into. an evaporator; and the refrigerant. in gaseousform is withdrawn from the evaporator into the. come pressor unit of. the refrigerating machinery in order to complete the cycle, The, water fromthe lower portion of the storage tank of" the hot water storage and supply system is admitted'via the inlet conduit into the lower portionof the chamber l9 and rises upwardly therethroughinto the outlet conduit 21 from which. it is discharged into the upper portion-of. the, storage tanknoted; As the water rises upwardly through thechamgber 39, it is heated by virtueof the heat exchange relation thereof, with therefrigeranty in the conduit '28. Since the water is arranged, ingood heat relation with both the. conduit28 and the structures 36 and 3.7., as previously noted; the water rises in the.chamber 19, due to a. thermos siphon action. and passes through, the, channels 54, and 46. It further will beobservedithat the refrigerant in the conduit 28 and the water inthe chamber l9. arearrangedin counter-flow relation so, as to provide amore. constant tem: perature gradient therebetween through the chamber I9; and the lower end ofthe chamber 19 accommodates the accumulation of floccul'ent limeiand other foreign materials that areprecipitated or settled out of the. water as it..rises. in the chamber. i9 about, the-conduit 28 and thestltucrtures 36 and 31.

Inmanufacturing the heat exchanger If), the tubefromwhich, the conduit 28 is formedLmay be initially substantially circular in cross-section, whereby the tube is first flattened to'provid'e the substantially oval cross-section so that the con,- duit 28 has a larger surfacev areayrelative to the cross-sectional area thereof. The structures 36 and 31 may be suitably formed fromsheetstock. The structure 35 may thenbe wrapped aroundan appropriate mandrel; then the conduit 28* may be wrapped in helical form aroundthe structure 36; and then the structure 31 may be-wra-pped around thehelical conduit 28'. The inlet connector 29 and the outlet connector 30 are then suitably secured to the opposite-endsof the con-- duit 28' or suitably fashioned from the tubing thereof; This subassembly is thenremoved from the mandrel and assembled upon the inner member I I. At thistime, the inlet connectonzfl is arranged to project through the opening: 31

formedinthe flange l1; and the outlet'connector 30 is arranged to project through the opening formed in the lower portion of the side wall I2. The packing gland 32 is assembled upon the outer end of the inlet connector 29 in order to provide the fluid-tight joint between the inlet connector 29 and the adjacent wall of the flange I'I surrounding the opening 3i formed therein. Also the outlet connector 33 is suitably welded, as indicated at 33, into the opening formed in the lower portion of the side wall I2 in order to provide the fluid-tight joint therebetween. The outlet fixture 21 is suitably secured in the associated opening provided in the flange IT in order to provide the fluid-tight joint therebetween; and the inlet conduit 24 is suitably threaded in the associated spud 23 provided in the bottom wall I6 in order to provide the fluid-tight joint therebetween. Also the elbow 34 is secured to the inner end of the outlet connector 33; and the riser conduit 35 is suitably secured to the elbow 34. At this time, the complete subassembly of the inner member II, the conduit 23 and the structures 36 and 31 may be assembled with respect to the outer member M, the sealing gasket 20 being arranged between the adjacent surfaces of flanges IT and I8. Ultimately the bolts 2| are positioned and the cooperating nuts 22 are set so as to provide the fluid-tight chamber I 9. At this time, the inlet connector 29 and the riser conduit 35 may be appropriately plumbed into the refrigcrating machinery, as previously explained, and the inlet conduit 24 and the outlet conduit 27 may be appropriately plumbed into the hot water storage and supply system, as previously explained.

In the construction of the heat exchanger I3,

. it is preferable that the inner member IE, to-

gether with the flange I I, and the outer member I4, together with the flange I8, are formed of steel; and the conduit 28 and the structures 33 and 3'! are formed of copper or brass. By forming the conduit 28 and the structures 36 and 31 of copper, excellent heat exchange therebetween is obtained; and by forming the members I I and I4 of steel, heat exchange thereto from the structures 36 and 31 is retarded. In order further to insure heat exchange between the conduit 28 and the structures 36 and 37, this sub-assembly, as a whole, may be tin-dipped prior to assembly upon the inner member H in the manner described above; although this precaution is not ordinarily necessary. Moreover in order further to retard the heat-exchange between the structures 36 and 3'! and the inner and outer members II and I2, the side walls I2 and I5 and the respective bottom walls I3 and I6 may be formed of stainless steel; however, this precaution is not ordinarily necessary.

It will be appreciated that the outer member I4 may be readily removed from the assembly of the inner member II, the conduit 28, and the structures 36 and 31 to facilitate cleaning of the chamber I9 by removal of the bolts H and the cooperating nuts 22. Moreover the provision of the plug 23 in the spud 25 carried by the bottom Wall I3 of the inner member I I provides for ready access into the interior of the chamber I9 when the inner and outer members I I and I4 are in assembled relation.

When the heat exchanger is incorporated in the associated refrigerating system and in the associated hot Water storage and supply system, in the manner previously explained, it is preferable to embed it in suitable insulating material, which insulating material is normally packed 6 within the cavity of the inner member II. This arrangement prevents loss of heat from the conduit 28 to the ambient air and other supporting elements.

Referring now to Figs. 4 to 6, inclusive, there is illustrated a modified form of the heat exchanger I33 that embodies the features of the present invention, and which is fundamentally of the construction of the heat exchanger I0, described above. In the interest of brevity, the construction and arrangement of the heat exchanger I00 will not be completely described as it will be understood that the principal elements thereof perform the same functions as the corresponding elements of the heat exchanger I3.

However the heat exchanger I00 embodies an improved arrangement of the structures I36 and I3? that are respectively arranged between the inner wall H2 and the conduit I28 and between the outer wall I I5 and the conduit I23, in that the structures I36 and I3? are of helical form so that the edges of adjacent convolutions thereof are disposed in spaced-apart relation. This arrangement prevents the conduction of heat from the upper portions to the lower portions of the structures I36 and 531, except through the long convolutions thereof. Thus the opposite extremities of the helical structures I36 and I3! are in fact spaced-apart a distance many times greater than that of the height of the cup-shaped chamber H3 defined between the innerand outer cup-shaped members III and H4.

Specifically in the structure I36, the flutes I38 of the corrugations terminate in rather sharp peaks 533 provided with pairs of inwardlyxextending projections or dimples I39a engaging the side wall H2 and in rather flat plateaus I40 engaging the convolutions of the conduit E28; whereby the area of contact between the structure H3 and conduit I28 is considerably greater than the area of contact between the structure I33 and the side wall I I2 so that in fact the structure 36 is arranged in good heat-conducting relation with the conduit I23 and in poor heat-conducting relation with the side wall I I2. Similarly in the structure I31, the flutes MI of the cor.- rugations terminate in rather sharp peaks I32 provided with pairs of outwardly extending projections or dimples I42a engaging the side wall I I5 and in rather flat plateaus I33 engaging the convolutions of the conduit I23; whereby the area of contact between the structure I3! and the conduit I23 is considerably greater than the area of contact between the structure I31 and the side wall H5 so that in fact the structure I31 is arranged in good heat-conducting relation with the conduit I28 and in poor heat-conducting relation with the side Wall H5. In order to locate the structure I36 with respect to the conduit I28,

pairs of outwardly extending projections or dimples, not shown, are carried on the plateaus itI'I and disposed in embracing relation with respect to the sides of the associated convolutions of the conduit I28; and in order to locate the structure I31 with respect to the conduit I23, pairs of inwardly extending projections, or dimples 13a, are carried on the plateaus I43 and disposed in embracing relation with respect to the sides of the associated convolutions of the conduit I23.

The arrangement of the structures I36 and I37, described above, not only provides for the long direct heat conducting paths between the adjacent convolutions thereof, but it also further minimizes the contact area between the strucouter wall and said conduit and in contact therewith, said conduit and said first and second structures being clamped between said inner and outer walls and supported in place therebetween in said chamber, means including pairs of spacedapart outwardly extending projections carried by said first structure and embracing the opposite sides of the turns of said conduit for locating said first structure and said conduit with respect to each other, and means including pairs of spaced-apart inwardly extending projections carried by said second structure and embracing the opposite sides of the turns of said conduit for locating said second structure and said conduit with respect to each other, said first structure accommodating ready passage of said first fluid in said chamber between said first structure and said inner wall, said second structure accommodating ready passage of said first fluid in said chamber between said second structure and said outer wall, said first and second structures accommodating ready passage of said first fluid in said chamber therebetween and into contact with said conduit, the area of contact between said first structure and said conduit being greater than the area of contact between said first structure and said inner wall and the area of contact between said second structure and said conduit being greater than the area of contact between said second structure and said outer wall so as to promote heat exchange between said first and second fluids and to retard heat exchange between said conduit and said inner and outer walls.

4. A heat exchanger comprising inner and outer tubular metal walls arranged in adjacent spaced-apart relation and cooperating to define a tubular chamber therebetween accommodating the passage therethrough of a first fluid, a substantially helical metal conduit arranged within said chamber and surrounding said inner wall and disposed in spaced relation with respect to said inner and outer walls and accommodating the passage therethrough of a second fluid, a first resilient corrugated sheet metal structure arranged in said chamber between said inner wall and said conduit and in contact therewith, a second resilient corrugated sheet metal structure arranged in said chamber between said outer wall and said conduit and in contact therewith, said conduit and said first and second structures being clamped between said inner and outer walls and supported in place therebetween in said chamber, means including pairs of spacedapart outwardly extending projections carried by said first structure and embracing the opposite sides of the turns of said conduit for locating said first structure and said conduit with respect to each other, means including inwardly extending first parts carried by said first structure and engaging said inner wall for locating said first structure and said inner wall with respect to each other, means including pairs of spaced-apart inwardly extending projections carried by said second structure and embracing the opposite sides of the turns of said conduit for locating said second structure and said conduit with respect to each other, and means including outwardly extending second parts carried by said second structure and engaging said outer wall for cating said second structure and said outer wall with respect to each other, said first structure accommodating ready passage of said first fluid in said chamber between said first structure and said inner wall, said second structure accommodating ready passage of said first fluid in said chamber between said second structure and said outer wall, said first and second structures accommodating ready passage of said first fluid in said chamber therebetween and into contact with said conduit, said first structure being arranged in good heat exchange relation with said conduit and in poor heat exchange relation by said first parts with said inner wall and said second structure being arranged in good heat exchange relation with said conduit and in poor heat exchange relation by said second parts with said outer wall so as to promote heat exchange between said first and second fluids and to retard heat exchange between said conduit and said inner and outer walls.

5. A heat exchanger comprising inner and outer tubular metal walls arranged in adjacent spaced-apart relation and cooperating to define a tubular chamber therebetween accommodating the passage therethrough of a first fluid, a substantially helical metal conduit arranged within said chamber and surrounding said inner wall and disposed in spaced relation with respect to said inner and outer walls and accommodating the passage therethrough of a second fluid, a first resilient corrugated metal structure arranged in said chamber between said inner wall and said conduit and in contact therewith, and a second resilient corrugated metal structure arranged in said chamber between said outer wall and said conduit and in contact therewith, said conduit and said first and second structures being clamped between said inner and outer walls and supported in place therebetween in said chamber, said first structure accommodating ready passage of said first fluid in said chamber between said first structure and said inner wall, said second structure accommodating ready passage of said first fluid in said chamber between said second structure and said outer wall, said first and second structures accommodating ready passage of said first fluid in said chamber therebetween and into contact with said conduit, the area of contact between said first structure and said conduit being greater than the area of contact between said first structure and said inner wall and the area of contact between said second structure and said conduit being greater than the area of contact between said second structure and said outer wall so as to promote heat exchange between said first and second fluids and to retard heat exchange between said conduit and said inner and outer walls, said first and second structures being of substantially tubular form and respectively extending substantially continuously around the exterior of said conduit and between the opposite ends thereof.

KEMPER M. HAMMELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,150,522 Jackson et al. Aug. 1'7, 1915 1,821,995 Wayman Sept. 8, 1931 1,822, 68 Summers Sept. 1931 1,903,826 Mallory Apr. 18, 1933 1,967,106 Steenstrup July 1'7, 1934 1,970,105 Smith Aug. 14, 1934 2,233,031 Price Feb. 25, 1941 2,343,727 Zenner Mar. 7, 1944 2,432,475 Griflith Dec. 1 47

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1150522 *Jul 27, 1914Aug 17, 1915Samuel E JacksonWater-heater.
US1821995 *Mar 28, 1929Sep 8, 1931Frigidaire CorpRefrigerating apparatus
US1822068 *Mar 28, 1929Sep 8, 1931Frigidaire CorpRefrigerating apparatus
US1903826 *Feb 14, 1930Apr 18, 1933Climax Engineering CompanyRefrigerating apparatus
US1967106 *Aug 26, 1931Jul 17, 1934Gen ElectricCondenser for refrigerating machines
US1970105 *Mar 24, 1932Aug 14, 1934Fedders Mfg Co IncCondenser and method of making the same
US2233031 *Jun 13, 1939Feb 25, 1941Sirius CorpAircraft power plant supercharger
US2343727 *Apr 26, 1941Mar 7, 1944Linde Air Prod CoVaporizing device
US2432475 *Aug 18, 1944Dec 9, 1947Frank H GriffithOil filter and conditioner
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2767962 *Oct 10, 1952Oct 23, 1956Blackburn Louis AVacuum milk tank
US2961853 *Jul 10, 1958Nov 29, 1960Cohrt Henry FRefrigeration apparatus
US3100523 *May 29, 1959Aug 13, 1963Borg WarnerHeat exchanger
US3255609 *May 25, 1964Jun 14, 1966Jet Spray Cooler IncBeverage dispenser
US3326281 *May 24, 1965Jun 20, 1967Tylde Water BoardFreezing tank
US3479144 *Sep 22, 1964Nov 18, 1969United Aircraft CorpCatalytic burner
US3490878 *Apr 28, 1965Jan 20, 1970United Aircraft CorpCatalytic burner
US3910542 *Mar 4, 1974Oct 7, 1975Garrett CorpHeat exchanger mounting device
US4216937 *Jul 18, 1975Aug 12, 1980The Garrett CorporationHeat exchanger mounting device
US4355780 *Mar 17, 1980Oct 26, 1982The Garrett CorporationHeat exchanger mounting device
US4865124 *Feb 21, 1986Sep 12, 1989Dempsey Jack CShell and coil heat exchanger
US5379832 *Jul 20, 1993Jan 10, 1995Aqua Systems, Inc.Shell and coil heat exchanger
US5406930 *Aug 10, 1993Apr 18, 1995Atd CorporationOutdoor cooking device
US5408071 *May 19, 1993Apr 18, 1995Atd CorporationElectric heater with heat distributing means comprising stacked foil layers
US5487423 *Dec 5, 1994Jan 30, 1996Piscine Service Anjou SaHeat exchanger
US5800905 *Sep 19, 1995Sep 1, 1998Atd CorporationPad including heat sink and thermal insulation area
US5845704 *May 16, 1997Dec 8, 1998Flowserve Management CompanyHeat exchanger baffle design
US6076597 *Dec 31, 1997Jun 20, 2000Flowserve Management CompanyHelical coil heat exchanger with removable end plates
US6102106 *Jul 14, 1999Aug 15, 2000Flowserve Management CompanyMethod of servicing a helical coil heat exchanger with removable end plates
US6276356Jul 9, 1999Aug 21, 2001Atd CorporationPortable gas grill
US6354103 *Jun 4, 2001Mar 12, 2002Fred Evans, Sr.Vertical heat exchange unit
WO1993026135A1 *Jun 8, 1993Dec 23, 1993Atd CorpHeat distributing device
Classifications
U.S. Classification165/156, 165/69, 165/169, 165/135
International ClassificationF28D7/02, F28D7/00
Cooperative ClassificationF28D7/024
European ClassificationF28D7/02D