US2012891A - Evaporator - Google Patents

Description

G. B. PALMER, JR" El AL EVAPORATOR I Filed April 15, 1933 2 Sheets-Sheet, l

, INVENTORS George B. PaImerJF: Ray 8. Grubba P1117)? Mrksner Aug. 27, 1935. G. B. P LME 'JRQ, YETAL' 2,012,391

EVAPORATOR Filed April 15, 1933 z Shets-Shet 2 INVENTORS George B. Pa7mer Ji:

Ray .8. Grupba P11172190 Nwsner ATTORNEYS Patented Aug. 27, 1935'- UNITED STATES PATENT OFFICE EVAPORATOR George B. Palmer, Jr., Detroit, Bay B. Grubba, Center Line, and Philip Missner, Detroit, Mich, assignors to -McGord Radiator & Manufacturing Company, Detroit, Mich, a corporation of Maine Application April 13, 1933, Serial No. 665,848

' 7 10 Claims. (01. 624-95) 5 frigerating machines.

An object of the invention is to improve the structure of the evaporator with a view to simplifying the construction and improving the operation thereof, thereby providing a more efficient, economical and,,in general, a more satisfactory and desirable unit.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. 1 is a perspective view of a domestic evaporator or refrigeration unit embodying the invention.

Fig. 2 is a fragmentary section taken through lines 2-2 of Fig. l in the direction of the arrows.

Fig. 3 is a rear end elevation, partly broken away, of the structure shown in Fig. 1.

Fig. 4 is a vertical sectiontaken through lines 44 of Fig. 3 in the direction of the arrows.

Fig. 5 is a fragmentary section taken through lines 5-5 of Fig. 2 in the direction of the arrows.

Fig. 6 is a fragmentary perspective view illustrating another embodiment of the invention.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of "parts illustrated in the accompanying drawings, since the invention is capable of-other embodiments and of being practiced or carried 'out in various ways. Also it is tobe understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

Referring to the embodiment of the invention illustrated in Figs. 1 to 5 inclusive, the evaporator unit in this instance is shown, for example, as having two ice tray compartments, although it is understood that a lesser or greater number may be provided. The lower compartment is formed by means of a. sleeve A which comprises a sheet metal blank pressed into U eshape to provide top and bottom walls It! and II and'a rear end "wall l2, the .front of the sleevebeing open to permit introduction of an ice tray. The upper sleeve .8, in like manner, comprises a sheet metal blank bent into U-shapeito provide top and bottom which are bent beneath the bottom wall I l of the horizontal walls I3 and H and a vertical rear end wall I5, the front of this sleeve also being open for the insertion of an ice tray. A common heat conducting or heat transfer means is provided for closing the sides of the sleeves or compartments 5 A and B, and in the present instance this is acoomplished by means of a series ofmetallic angle members C positioned side by side and constructed to provide at once the side walls for the ice forming compartments and projecting heat absorbing fins. Accordingly the members C are positioned so that corresponding flanges l6 thereof lie in the same vertical plane and in abutting relation thus preferably completely closing the sides of the sleeves A and 13. Moreover, the members C are arranged so that the flanges -l'| thereof project outwardly from the sleeves in spaced parallel relation thus afiording considerable area. for the transfer of heat.

The sleeves A and B are properly positioned and clamped to the angle members C by means of lugs or tongues formed from the metal of the angles. The flanges 16 are cut away adjacent the top wall I3 and tongues l8 are formed by slitting the metal at the juncture of the flanges I6 and I1, these tongues being bent over the wall B of the upper sleeve. In like manner the angles at their lower ends are slit at the juncture of the flaiiges l6 and H, to provide tongues or lugs 2| lower sleeve. Intermediate these points the metal of each flange I6 isslit and spaced lugs l9 and 20 pressed inwardly between the sleeves to engage the walls I4 and I0 respectively. Thus, by means of the series of tongues or lugs l8--2l the various angle members. C will be assembled on the sleeves and the latter will be supported therefrom in proper positions.

The evaporator unit may be suspended within the refrigerator box or cabinet by means-of U- shaped hanger members 23 positioned at opposite ends thereof. Each of these hanger members comprises an upper transverse portion, adapted to be secured to the inner side of the top wall of the cabinet, having depending side members 24 and 25 secured to the flanges I6 ofthe angles at the front and rear ends of the unit.

In the present instance the tubing or conduit for the refrigerant is a continuous length of pipe bent or coiled into a series of courses extending up beneath the bottom ll of the lower sleeve A, another series of courses interposed between the two sleeves A and B, and other courses imposed on the top I! of the upper sleeve. One method of forming the tubing and arranging the walls in i heat conductive relation with the sleeves so as to produce the lowest practicable temperature for the freezing of ice blocks within the ice trays, is herein illustrated.

The refrigerant is conducted through a connecting tube 28 to the tube coils associated with the ice tray sleeves, the refrigerant entering the tubing in the usual manner through an expansion valve (not shown) connected to the coupling 21.

From the connecting tube or conduit 23 the refrigerant'first flows through a series of tube coils 23 having the courses thereof in contact with the bottom wall ll of the lower sleeve. Thence the refrigerant flows through a connecting tube 29 to a series of intermediate coils 30 having similar courses interposed between the sleeves A and B and in direct contact with the adjacent walls l0 and H thereof. Thence the refrigerant flows through the connecting conduit iii to an upper coil section 32.

In the present embodiment the upper tube section 32 is bent to extend longitudinally along one edge of the upper sleeve, then transversely at 32c, and is then return bent to extend along the opposite longitudinal edge at 32b. From the outlet 320 the refrigerant is conducted to the compressor. The upper tube section 32 in this instance therefore comprises three courses in direct thermal contact with the upper wall l3 of the sleeve B and also in direct thermal contact with the fin portions II. It will be noted that each fln C at its upper end has an inwardly offset portion 33 of increased area adapted to overlie bne of the longitudinal courses of the tube coil 32, this offset portion of each fin being notched at 34 to fit over the tubing.

In the embodiment of the invention illustrated in Fig. 6 the general construction of the evaporator coincides substantially with that above described with the exception that the upper section of tubing is in this instance formed with a series of superimposed courses. The refrigerant, flowing from the intermediate coils 30 through the communicating section 3|, is conducted through the tube course 35 and thence through coils having vertically spaced courses 36 and 31. Thence the refrigerant passes through a connecting tube 38 into a series of vertically spaced courses 39, 40 and II. The heat absorbing fins C are preferably thermally connected with each of these courses at opposite longitudinal sides of the evaporator. Accordingly the courses 36 and 31 are offset inwardly from the course 35 and in like manner the courses 39 and 40 are offset inwardly from the bottom course 4|. The upper ofl'set portion 33 of each fin is provided with notches 34, 42 and 43 embracing the several pipe croiursgs in the manner clearly illustrated in The present invention provides an evaporator having the desirable features of rapid freezing of the water in the ice tray compartments, minimum dehydration in the refrigerator cabinet, greater efliciency inoperation together with substantial economies resulting from the improved and simplified construction. Dehydration is minimized in the present evaporator as a result of the relatively large heat transfer area-and 'the maintenance of as high a temperature as possible in the fin areas. The ice tray sleeves are maintained at a low temperature so as to produce fast freezing of the ice blocks, this being secured by the arrangement of the tube courses in contact with the top and bottom walls of each of the ice tray sleeves, thus providing the lowest possible sleeve temperature with any predetermined temperature of refrigerant. By constructing the fins in such manner that they will form the side walls of the sleeves, and by connecting the upper ends of these fins with the upper-tube coils atthe top of the ice tray compartments, these fin surfaces are at all'times in direct heat exchange relation with the ice tray sleeves although maintained at a higher temperature.

The path of the refrigerant is from the ex-- pansion valve to the coils or courses under the bottom of the lower ice tray sleeve, thence to the coils or courses interposed between the two sleeves, and finally the refrigerant is conducted through one or more turns or courses arranged on the top surface of the upper sleeve. Inasmuch as the warmest air reaching the evaporator comes in contact with the upper ends of the fins, the areas of which-are increased at these points, it will be apparent that the greatest heat load is placed on the top coil or courses of tubing. Consequently the refrigerant frost line rate of travel will be greatly retarded at the upper coil or courses of the tubing. In fact the frost line is maintained in the locality of the evaporator sleeves and is prevented from traveling down the suction line before the time lag in the thermostat or bulb has elapsed so as to out 01f the machine. In other words, the frost line is kept at the evaporator during the normal time lag of the thermostat prior to the stopping of the machine. ,In consequence of the fact that the fins thermally tie the upper and lower portions of the evaporator together, the longest practical cycle of operation is permitted for the reason that the entire evaporator unit must be warmed and cooled in order to operate the-thermostat. For

example, when water is placed in the ice tray compartments for freezing, the refrigerant reaches practically complete evaporation before leaving the tube courses associated, with the sleeves, yet efiicient cooling of the circulating air in the box is secured 'by virtue of the fins, the large area of which permits a rapid transfer of heat to the sleeves and thence to the refrigerant. The heat conduction between the lower and intermediate coiled tubing 28 and 30 and the sleeves A- and B may be augmented by soldering the tubing to the surfaces of the sleeves. It will be apparent that the lower courses 28 and 3B of the entire conduit will normally have a much lower temperature than the courses or portion 32,

' due to the fact that the refrigerant entering the the trays is accomplished, but since the refrigerant will nearly always be converted into gaseous condition by the time it enters the upper section of tubing 32, due to the absorption of heat from the water as well as.,the air circulating in the refrigerated area, the frost line at no time will travel an appreciable extent into the upper coil of the tubing.

Where it has been attempted in previous constructions to isolate the upper finned coil from the lower coils in contact with the ice tray sleeves and to protect the upper coil against material heat exchange with other portions of the evaporator, and where the thermostat is responsive to the relatively warm temperature in this isolated upper coil, it has been found that any substantial cooling of the circulating air within the refrigerator cabinet is. impossible until prac-.

the upper coil, very slight absorption of heat from the circulating air is possible. This condition tends to produce a wide range-of variation of temperature within the refrigerator compartment. Moreover, after the water has been completely frozen in the trays and the liquid refrigerant in the ice tray coils no longer has a source for the absorption of heat so as to vaporize it, the refrigerant will flow directly into the upper isolated coil. vaporization of this refrigerant is then accomplished by absorption of heat from the circulating air, and since the thermostatic control is in this area and is at this time subject to a considerable drop in temperature, the result either is that the machine is prematurely cut off, thus inefficiently cooling the air within the ice box, or too low a temperature is produced within the cabinet.

These disadvantages are overcome in the present evaporator since the fin, sleeve and tube relation is such that an eflicient absorption of heat from the circulating air continues at the proper rate throughout the operation of the evaporator and the freezing of the ice without, however, retarding appreciably the rapidity of its freezing. The arrangement of the lower coil portions 28 and 30 inintimate contact with the sleeves induces .the greatest amount of heat absorption in the locality of the ice trays, thus rapidly freezing the ice.

It will be noted that e upper relatively warmer portion 32 of the conduit (also the por tions 351-4! in Fig. 6) is not isolated from the lower coil portions so as to confine the cooling of the circulating air to the limited heat absorptive effectiveness of thisupper portion of the conduit. On the other hand, this upper conduit portion is I thermally connected to the ice tray sleeves by means of the fin and side wall construction, which Y provides a large radiating area, and consequently there is at all times a material flow of heat from the circulating air through the fins to the sleeves and thence to the cold portions of the refrigerant tubes. It will be noted also that a distinct temperature gradient will occur in which the fin surfaces will at all times be at a predetermined higher temperature than the ice tray sleeves, so that the circulating air will, therefore, be cooled to theproper temperature. The temperature differential'between the circulating air and the ice compartments can, therefore, be maintained substantially uniform, aifording important to note that, although practically complete evaporationftakes place in the conduit before the refrigerant passes into the upper tube-section, yet refrigeration of the circulating air proceeds simultaneously with the freezing of the ice because the fins are directly subject to temperature conditions in the sleeve regions while being out of direct heat exchange relation with the colder or heat absorptive regions of the refrigerant tubing. H We claim:

' 1'. 'linvaporator comprising a plurality of spaced superimposed U-shaped sleeves each forming the top, bottom and an end wall of an ice forming compartment, 9. continuous conduit comprising portions thermally contacting with the top and bottom walls of each sleeve, and a series of juxtaposed plates forming theside walls of said sleeves and provided with projectingfins thermally connected with portions of the conduit disposed above the uppermost sleeve.

3. An evaporator including a U-shapedjsleeve forming the top, bottom and an end wall of an ice tray compartment, a refrigerant containing conduit arranged in heat conductiverelation to the sleeve, and a plurality of angle members secured to the top and bottom of said sleeve to form the side walls of the compartment andprovide vertically extending and outwardly projecting heat exchanging fins.

4. An evaporator including a one piece U- .shaped sleeve forming the top, bottom and an end wall of an ice tray compartment, a refrigerant containing conduit arranged in heat conductive relation to the sleeve, and a plurality of angle members secured to the top andbottom of said sleeve vertically thereof to form the side walls of the upper ends of the fins being inwardly offset to overlie the'sleeve and engage the upper conduit portion.

6. An evaporator unit for refrigerators comprising a U-shaped sleeve providing the top, bottom and an end wall of an ice tray compartment, 2. continuous refrigerant containing conduit having portions arranged beneath and above the sleeve, compartment side wall members connected to. the sleeve and having spaced vertically extending fins provided at their upper ends with ofls'et portions overlying the sleeve and notched to embrace the upper conduit portion.

'7. An evaporator unit for refrigerators comprising a plurality of U-shaped sleeveseach providing the top, bottom and an end wall of an ice tray compartment, refrigerant containing tubing having portions arranged beneath, between and above the sleeves, a series ofv juxtaposed plate members forming the side walls of the compartments and connected to the sleeves, said members.

viding the top, bottom and an end wall'of an ice tray compartment, refrigerant containing tubing having portions arranged beneath, between and 4 above the sleeves, a series of juxtaposed plate members forming the side walls of the compartments and connected to the sleeves, said members having vertically extending fins at opposite sides of the sleeves and said fins beingenlarged in area at their upper ends and in direct thermal contact with the tubing only in the locality of. said areas.

9. An evaporator unit for refrigerators comprising a plurality of U-shaped sleeves each pro- 10. An evaporator unit for refrigerators comprising a plurality or U-shaped sleeves each providing the top, bottom, sides and an end wall of an ice tray compartment, refrigerant containing tubing having portions arranged beneath, between and above the sleeves, and a series of vertically extending flns directly connected to opposite sides of said sleeves and having a height greater than the combined height oi the sleeves,

said fins at their upper ends engaging that por- 10 tion of the tubing arranged above said sleeves.

GEORGE B. PALMER, Jn.

RAY B. GRUBBA. PHILIP mssmm.v

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