US2794331A - Cooling unit for absorption refrigeration apparatus - Google Patents

Description

4 Sheets-Snes# 1 W. G. KOGEL Julie 4,1957

comme UNIT FoRBsoRPTIoN REFRIGERATION .APPARATUS Filed sept. 20, 1954 June 1957 Filed Sept. 20, 1954 W. G. KOGEL COOLING UNIT FOR ABSORPTION REFRIGERATION APPARATUS 4 Sheets-Sheet 2 lNlTOR:I

fedi/XM1 June 4, 1957 w. Koen-:L COOLING UNIT FOR ABSORPTION REFRIGERATION APPARTUS 4 She'ets-Sneet 3 Filed Sept. 20, 1.9 54

w. G. Koel-:L

` 4 Sheets-snoei 4 v i OR.

wJ/f/M June 4, 1957 i comme UNIT Foa Asonpnou REFRIGERATION APPARATUS' Filed sept. 2p, 1954 COOLING UNIT FR ABSORPTION REFRIGERATION APPARATUS Wilhelm Georg Kogel, Stockholm, Sweden, assigner to Aktiebolaget Elektrolux, Stockholm, Sweden, a corporation of Sweden Application September 20, 1954, Serial No. 456,920 Claims priority, application Sweden November 28, 1953 12 Claims. (Cl. 62-119.5)

My invention is concerned with the cooling of a thermally insulated interior of a refrigerator, and more particularly to cooling units for refrigeration apparatus for eecting such cooling.

Itis an object of my invention to provide an improved arrangement for transmitting cooling effect to a compartment of a refrigerator cabinet which takes up a minimum amount of useful storage space in the compartment. I accomplish this by positioning an evaporator element of refrigeration apparatus in the thermally insulated wall structure of a refrigerator cabinet, and by employing a heat transmitting member having a first part which is heat conductively connected to the evaporator element and a second part which extends into a compartment formed by the wall structure, such second part passing through an opening formed in an inner lining of the wall structure.

` Another object is to provide such an improvement for transmitting cooling effect to the upper part of a freezing compartment when another evaporator element of the refrigeration apparatus is associated with the bottom of such a compartment.

A further object is to provide such an improvement for transmitting cooling effect to the upper part of a eezing compartment in which liquid refrigerant is always made available to the evaporator element heat conductively connected to the heat transmitting member, even when the evaporator element associated with the bottom of the freezing compartment is at an adequately low temperature.

A still further object is to provide such an improvement for transmitting cooling effect to a compartment of a refrigerator cabinet in which the evaporator element positioned in the thermally insulated wall structure of the cabinet forms part of absorption refrigeration apparatus of the inert gas type.

A still further object is to provide such an improvement for transmitting cooling eifect to the upper part of a freezing compartment in which the evaporator elements form part of such absorption refrigeration apparatus, and supplying heat to the latter at one rate when the temperature of the other evaporator element associated with the bottom of the freezing compartment tends to rise above a desired low value, and also supplying heat to the refrigeration apparatus at a second lower rate, even when the temperature of the other evaporator element is at the desired low value, so that liquid refrigerant will always be made available to the evaporator element heat conductively connected to the heat transmitting member.

The invention, together with the above and other objects and advantages thereof, will be more fully understood upon reference to the following description and accompanying drawings forming a part of this specification, and of which:

Fig. l is a fragmentary vertical sectional view of a refrigerator embodying the invention;

v Fig. 2 is a horizontal sectional view, taken at line 2-2 of-Fig. l,- to illustrate details more clearly;

ice

Fig. 3 illustrates more or less diagrammatically absorption refrigeration apparatus of the inert gas type which may be employed in the refrigerator shown in Figs. l and 2;

Fig. 4 illustrates an alternative form of a cooling unit which may be employed in the embodiment of Figs. 1 and 2;

Fig. 5 is a fragmentary vertical sectional view of a refrigerator illustrating another embodiment of the invention;

Fig. 6 illustrates more or less diagrammatically parts of the refrigeration apparatus employed in the refrigerator shown in Fig. 5; and

Fig. 7 illustrates more or less diagrammatically additional parts of the refrigeration apparatus employed in the refrigerator shown in Fig. 5.

Referring to Figs. l and 2, I have shown the invention embodied in a refrigerator comprising a cabinet 10 having an inner metal shell 11 arranged to be supported Within an outer metal shell 12 and insulated therefrom with any suitable insulating material 14. The inner metal shell or lining denes a thermally insulated interior 15 into which access is afforded by a door (not shown) Which is hinged to the front of the cabinet and in its closed position closes the access opening 16. Hence, the thermally insulated interior 15 provides a storage space formed by the thermally insulated wall structure of the cabinet 10.

The thermally insulated storage space or compartment 15 of the cabinet 10 is arranged to be cooled and maintained at a low temperature by absorption refrigeration apparatus of a uniform pressure type, like that diagrammatically shown in Fig. 3, in which an inert gas or pressure equalizing fluid is employed. In order to simplify Fig. 3, the absorption refrigeration apparatus has been illustrated in a more or less conventional manner apart from the refrigerator cabinet shown in Figs. 1 and 2. In refrigeration apparatus of the type shown in Fig. 3, a refrigerant fluid, such as liquid ammonia, for example, is introduced through a conduit 17 into an evaporator 18. In the evaporator 18 the refrigerant fluid evaporates and diffuses into an inert gas, such as hydrogen, for example, to produce refrigeration and abstract heat.

The resulting gas mixture of refrigerant and inert gas ows from the evaporator 1S through an outer passage of a gas heat exchanger 19 and vertical conduit 20 into an absorber comprising a Vessel 21 and a looped coil 22. In the absorber vessel 21 and coil 22 the refrigerant vapor is absorbed by a suitable absorbent, such as water, for example, which is introduced into coil 22 through a conduit 23. The hydrogen or inert gas, which is practically insoluble and weak in refrigerant, returns to the evaporator 1S from coil 22 through a conduit 29a, an inner passage of the gas heat exchanger 19 and a conduit 24.

From the vessel 21 enriched absorption liquid ows through a conduit 25 and inner passage of a liquid heat exchanger` 26 into the lower end of a vapor lift tube 27 of a generator or vapor expulsion unit 2S. The generator 28 comprises a heating flue 29 having the vapor lift tube 27 and a boiler pipe 30 in thermal exchange relation therewith, as by welding, for example. By heating generator 28, as by a suitable source of heat, as an electrical heating element or a gas burner 31, for example, liquid from the inner passage of the heat exchanger 26 is raised by vapor lift action through tube 27 into the upper part of the boiler pipe 30. The liberated refrigerant vapor entering boiler pipe 30 from the tube 27, and also vapor expelled from solution in the boiler pipe, ows upwardly into an air cooled condenser 32' provided with a plurality of heat dissipating members or iins 33. Refrigerant vapor is liquefied in the condenser 32 and returns to the evaporator 18 through the conduit 17 to complete the refrigerating cycle.

The weakened absorption liquid from which refrigerant vapor has been expelled, is conducted from boiler pipe 38 through a conduit 34, outer passage of the liquid heat exchanger 26 and conduit 23 into the upper part of the coil 22. The lower end of the condenser 32 is connected by a conduit 35 to the gas circuit, as to the upper part of conduit 26, for example, so that any non-condensable gas which may pass into the condenser, can ow to the gas circuit and not be trapped in the condenser.

The evaporator 18 comprises pipe or conduit sections 18a and 18h which are connected by a bend 36 and for convenience may be referred to as evaporator elements. The evaporator elements 18a 'and 18h are connected in series relation with inert gas from conduit 24 owing through evaporator element 18a in the presence of and in parallel ow with liquid refrigerant which is introduced through conduit 17. Unevaporated liquid refrig-v erant is conducted from the lower part of evaporator element 18a through the connecting bend 36 into the lower evaporator element 18b for flow in the latter in the presence of and in parallel ow with the inert gas.

Since the inert gas flows successively through the evaporator elements 18a and 13b, the gas in the upper evaporator element 18a contains a lesser amount of refrigerant vapor than the gas in the lower evaporator element 1819. The partial vapor pressure of the refrigerant is a gradient, so that the temperature of liquid refrigerant in the evaporator elements is also a gradient, the evaporating temperature of the liquid being lower in the upper evaporator element 18a which desirably constitutes the freezing portion of the evaporator 18.

In order to precool liquid refrigerant conducted to the upper evaporator element 18a through the con-duit 17, the latter is connected at spaced apart regions to the outer passage of the gas heat exchanger 19 by conduits 37, as shown in Fig. 3. In this way, natural circulation of inert gas from the outer passage of the gas heat exchanger 19 takes place through a part of conduit 17 and evaporation and diffusion of refrigerant into inert gas takes place, thereby taking up heat from liquid refrigerant before being introduced into the evaporator 18.

In Figs. l and 2, in which parts corresponding to those shown in Fig. 3 are designated by the same reference numerals, the gas heat exchanger 19 is embedded in a body of heat insulating material 38 retained in a removable cover or closure 39 for an opening 40 in the rear insulated Wall 41 of the cabinet 10. The cover 39 comprises a rectangular frame 42 formed of suitable material, such as wood, having inner and outer plates 43 and 44, respectively. The inner plate 43 is depressed about its peripheral edge so that, when the cover 39 is positioned at the opening, the greater part of the inner plate will be substantially flush with the inner shell 11, and the depressed peripheral edge thereof will bear against a gasket 4S adapted to be held against the inner shell 1'1. The outer plate 44, which is of greater area than the opening 40, is removably secured at 46 to the outer shell 12.

The gas heat exchanger 19 is arranged in a lengthwise position within the cover 39, and is disposed in the plane of the rear wall 41 of the cabinet whenthe cover 39 is positioned at the opening 40. A part of the liquid refrigerant supply conduit 17, at the section thereof having the conduits 37 connected thereto, is positioned above and to one side of the gas heat exchanger, .as seen in Figs. l and 2. Hence, the liquid refrigerant connection, and the connections 2? and 20a to the gas heat exchanger 19, are embedded in the insulation 38. It will be seen in Figs. .l and 2 that the liquid refrigerant conduit 17 and conduits 20 and 26a in the gas 4circuit project through openings in the rear or outer plate 44 of the coverk 39 into a vertically extending'space 47 at the rear of the cabinet. Other partsof the refrigeration system,vsu'ch 4 as the condenser and absorber, for example, are located in the space 47 to promote air cooling of these parts.

The cover 39 desirably may form a unitary part of the refrigeration system. In such case, the cover 39 will tit snugly in the opening 40 formed by frame structure 48 in the rear wall 41 when the different parts of the refrigeration system are positioned in the Vvertically extending space 47.

In accordance with my invention, in order to provide a maximum amount of storage space in the compartment 15 and effectively transmit cooling effect thereto, the evaporator 18 of the refrigeration apparatus is positioned in the thermally insulated wall structure of the cabinet 10; and members 50 and 51, which are heat conductively -connected to the evaporator 18, extend into the compartment 15 through an opening 52 in the lining 11. In the preferred embodiment shown in Figs. l and 2, the conduit sections or elements 18a `and 18b of the Vevaporator 18 are positioned in the cover part 39 of the rear wall 41 of the cabinet 10, and are com-A pletely embedded in the insulating material 38.

The evaporator elements 18a and 181i are located closely adjacent to the inner wall plate 43 of the cover 39, so that these elements will be as near as possible to the inner lining 11 when the cover or closure 39 is placed in position in the opening 40 of the rear insulated wall 41. The members 50 and 51 are formed of a good heat conducting material like aluminum, for example, for effectively transmitting cooling effect to the storage space or compartment 15.

In Figs. 1 and 2 the member 50, which extends across a major portion of the storage space 15 between the lateral side walls thereof, is bent about the top evaporator element 18a and includes an end portion 50a which extends forwardly through the opening 52 in the lining 11 and serves as a spacer between the members 50V and 51. The member 51 is bent about the bottom conduit section 18b and includes an end portion 51a which also extends forwardly through the opening 52 in the lining 11'sand is in contact with the underside of the member 51. In order to provide a good heat conductive connection between the evaporator elements 18a and 18b and the end portions 50a and 51a of the members 50 and 51, respectively, these parts are effectively united to one another in any suitable manner. A suitable gasket (not shown) may be provided at the narrow opening 52 yand at the adjacent opening in plate 43 of the cover 39 to thermally insulate the members 50 and 51 and end portions 50a and 51a thereof from the regions of the inner lining 11 at the immediate vicinity of such opening,

Since the evaporator 18 is Acompletely embedded in the insulating material 38, essentially the entire useful cooling effect produced by the evaporator is effectively transferred to the parts of the Vmetallic members 50 and 51 extending into the insulated wall structure through the ope-ning 52 in the inner lining 11. The rearwardly extending parts of the members S0 and 51 passing into the insulated wall structure serve as heat conductors for transmitting cooling effect to the parts of the members 50 and 51 disposed within the storage space 15. In Figs. l Iand 2, it will be seen that the members 50 and 51 essentially form part of a single unit 53 for transmitting cooling effectV to storage space 15 which is heat conductively connected to both the low and higher temperature evaporator elements 18a and 18b of the evaporator 18. The refrigeration apparatus desirably is operated so that the top member 5 which is heat conductively connected to the freezing portion 18er of the evaporator 18, can be effectively employed for freezing water and other matter to be frozen. Hence, the member 50 is essentially at and forms a shelf which is closely .adjacent to and at the vicinity of the ceiling of the storage space 15, and upon which may be placed matter to be frozen, such as ice trays filled with water, for example.

or removable WallV Both' the members 5i) and 51 are'elfeclively employed for cooling air in the storage space 15. In order to provide a relatively extensive heat transfer surface for A transferring cooling eect to air circulating in storage space 15, the area of the bottom member 51 preferably is the same Ias that of the top member 50. In this way, air owing in intimate Contact with the underside of member 51 is cooled and tends to move downwardly in the storage space 15, thereby displacing warmer air which moves upwardly into intimate contact with the underside of the member 15. Hence, natural circulation of air is induced in the storage space 15, in the manner just described, such air circulation being greater in that part of storage space 15 below the member 50 than in the part thereof above the member 50. Under these conditions, the member 50 is primarily employed for freezing water and other matter, although it also is effective to cool air owing in intimate contact therewith. Such air cooled by member 50 moves downwardly about the peripheral edge portions of the members 50 and 51 to displace warmer -air that moves upwardly in the space 15.

The unit 53 disposed within the storage space 15 and the evaporator 18, which is embeddel in insulation in the removable cover 39 in the rear insulated wall 41, form an arrangement which is especially useful in refrigerators where lit is desired to provide a maximum `amount of useful storage space in the thermally insulated interior of the refrigerator. This is particularly true in refrigerators of small size, for example, in which the storage space l is relatively small and in the neighborhood of 1.5 cubic feet, for example. By providing the cooling arrangement of Figs. l and 2 in a refrigerator of the small size just indicated, in which the unit 53 occupies and takes up very little space in :a vertical direction within the compartment 15, the useful storage space has been increased about l0 percent compared to the useful storage space obtained when a conventional cooling arrangement isV employed in which the evaporator of the refrigeration apparatus is disposed within the compartment.

Instead of providing a single unit 53 for transmitting cooling effect to the storage space 15 and matter disposed therein, as shown in the embodiment of Figs. l and 2 and just described, the members heat conductively connected to the evaporator elements 18a and 18b and disposed in the storage space 15 may be separated from one another. Such a modified arrangement is shown in Fig. 4 in which a member 150 is heat conductively connected to the low temperature evaporator element 18a, and a member 151 is ,heat conductively connected to the evaporator element 13b. The member 150 is formed to provide two horizontally extending shelves or supporting surfaces 150a and 150b which are essentially tangential to the top and bottom sides of the top evaporator element 18a, and desirably extend across a major portion of the distance between the lateral side walls of the storage space 15. Since the evaporator element 18a constitutes the freezer portion of the evaporator, the shelves 150a and 150b may be eiectively employed for freezing water in shallow trays and other matter to be frozen. The member 151, having an Iarea smaller or the same as that of the shelves 150:1 and 15911, may be provided with additional heat transfer members 151a at the underside thereof to provide a relatively extensive heat transfer surface for cooling air in the storage space 15. Also, the shelf 150 may occupy one part of the storage space 15 land the other shelf 151 may be laterally olset from the shelf 150 and occupy another part ofthe storage space 15;

The arrangement shown in Fig. 4, and just described, possesses the advantage that -additional shelving is provided upon Which food and yarticles may be placed. However, a number of openings 152a, 152b and 152e are necessary in the inner lining 11 through which the rearwardly extending parts of the Vmembers 150 and 151 extend into the insulated wall structure of the refrigerator cabinet.` As inthe first described embodiment of Figs. Vi and 2, a suitable gasket (not shown) may be provided at each of the openings 152a, 152b :and 152C and at the adjacent openings at the inner plate 43 of the cover 39 to thermally insulate the members 150 and 151 from the regions of the inner lining 11 at such openings.

In Figs. 5, 6 and 7 another embodiment of the invention is illustrated in which a unit 153, similar to the unit 53 in Figs. l and 2, is provided to transmit cooling eiect to the storage space to supplement the cooling eifect produced by the evaporator elements 118a and 118!) of evaporator 11S. The evaporator 11'8 forms .part of absorption refrigeration apparatus of the inert gas type and like that shown in lFig. 3 and described above.

In Fig. 6, in which parts similar to those shown in Figs. l, 2 and 3 are designated by the same reference numerals to vwhich 100 has been added, it will be seen that inert gas weak in refrigerant returns from the absorber (not shown) through a conduit .12la, inner passage of gas heat exchanger 119 and conduit 124 to an evaporator element 118C into which liquid refrigerant is supplied through a conduit 117 from .the condenser (not shown). By providing the conduit connections 137 between spaced apart regions of the conduit 117 and the outer passage of the gas heat exchanger 119, precooling of liquid refrigerant is effected before such liquid is introduced into the evaporator element 118C. From the evaporator element 118C inert gas flows successively through the evaporator elements y11811 and 118b, the outer passage of the gas heat exchanger 119 and .conduit 120 to the absorber, the conduit 120 being disposed within the conduit 12tla.

In Fig. 5 it will be seen that the gas heat exchanger 119 is disposed lengthwise of and embedded in insulation 138 retained in a cover 139 which closes an opening 140 in the rear insulated Wall 141 of the cabinet 110. The evaporator elements 118a and 118b, which are positioned in the :storage space 115, are in the form of looped coils disposed one above the other. Since the inert gas ilows successively through the evaporator elements 118a and 118b, the` evaporating temperature of liquid is lower in the evaporator element 118:1 which constitutes the freezing portion of the evaporator 118. Accordingly, a plate 154 may be heat conductively connected to the top part of the looped coil forming evaporator element 118a to provide a suitable supporting surface to receive matter 155 `to be frozen, such as ice trays containing water, for example. The upper looped coil and plate 154 connected thereto desirably extend across the full Width of the storage space 115 between the lateral side walls of the cabinet 11i). The higher temperature evaporator element 11819 is primarily employed to cool air in the storage space 115 and desirably may have heat transfer members 156 iixed thereto to provide a relatively extensive heat transfer surface to promote such air cooling.

The generator 128 forming a part of 'the refrigeration apparatus of Figs. 5 and 6 is illustrated in Fig. 7. The generator 128 comprises a boiler pipe 130 heat conductively connected to a heating tube 129 within which is positioned an electrical heat-ing element 131. Absorption liquid enriched in refrigerant iiows from an absorber (not shown) through a -conduit 125, -an inner .passage of a liquid heat exchanger 126 and conduit 157 into the Iboiler pipe 130. Absorption liquid from which refrigerant vapor has `been expelled flows from the bottom of boiler .pipe 130 into the lower end of a vapor-liquid lift 127 in thermal exchange relation with the heating tube 129. Due to heating elected by the electrical heating element 131, liquid is raised through the vaporliquid lift 127 by vapor lift action to the upper part of la `standpipe 1'58. l Y' Vapor expelled from solution in boiler pipe 130 flows from the upper end thereof to a condenser (not shown) in the same manner shown in the refrigeration apparatus of Fig. 3. VaporY passing from the upper end of thev vapor-liquid Ii-ft 127 into standpipe 158 ows therefrom through la conduit 159 to a region in boiler pipe 130 which serves as an `analyzer yand is located below the surface'level of the liquid column contained therein. After passing through the analyzer, such vapor mixes with expelled boiler vapor and also passes from the upper part of the boiler pipe 130 to the condenser (not shown). Absorption liquid weak in refrigerant ows from the lower end of standpipe 158, outer .passage of iiqui-d -heat exchanger 1126 and conduit 123 to the upper part of the absorber coil .(not shown). All of the generator parts just described are embedded in insulation 160 retained ina shell or casing 161.

An expansible Huid thermostat, which contains a suitable volatile -uid and responds to changes in temperature of evaporator element 11811, is provided to control a switch 162 connected in the electrical circuit of the heating element 131. The expansible fluid thermostat includes a Ibulb 163 which is in thermal exchange relation with the evaporator element 11811 and is connected by a tubular member 164 to a control device 165 operatively lassociated with the switch 162. The control arrangement shown is of the on and off type in which the thermal bulb 163 vbecomes effective to cause control device 165 to close switch 162 and complete an electrical circuit for the heating element 131 when the temperature of evaporator element 11811 increases due to increase in load on the refrigerator 110. Conversely, when the evaporator element 11811 reaches a predetermined low temperature, the thermal bulb 163 becomes effective `t-o cause control device 165 to open switch 162 and open the electrical circuit for the heating element. Electrical energy is supplied to the heating element from a source of supply through conductors 166 and 167, the switch 162 being connected in the conductor 166. A manually operable switch 168 is also connected in conductor 166 for manually controlling the supply of electrical'energy to the heating element.

In Fig. 5 it will be seen that the plate 154 connected to the upper evaporator element 11811 forms a partition to divide the ystorage space 11S into a freezing compartment 11511 and a higher temperature food compartment 1156, the freezing compartment 1,1511 being of adequate depth to receive ice trays, frozen food packages and other matter to -be frozen. The freezing compartment 11511 may be provided with a hood 16311, as indicated in dotted lines in Fig. 5, having a sui-table front closure member (not shown) Ywhich may be hinged to the front of the hood. While cooling effect is readily transmitted to matter that rests directly against the plate 154, diiculty Voften is encountered in transmitting cooling eifect to matter which is stored in the upper part of the freezing compartment 11511 and does not rest direct-ly against the plate 154.

In accordance with my invention, I provide the member 153 in thefreezing compartment 11511 which transmits cooling effect to the extreme upper part of such compartment and supplements the refrigerating effec-t produced by the evaporator element 11811 to which the plate 154 is connected. yThe member 153, which may lbe'iforrned of a suitable metal like copper or aluminum, for example, desirably extends across .the entire wid-th of the freezing compartment 11511 for transmitting cooling effect to all regions thereof. The member `153 includes alrst horizontally disposed section in the freezing compartment 11511, whichextends and passes through an opening 152 in the inner lining 111 into the removable cover 139. A gasket 170 is provided about the member 153 at the region thevlatter .passes through the openings in the lining 111 and plate 143, so that the member 153 willV be thermallyA insulated from such aperturd parts of the refrigerator` cabinet.

The member 153 is bent within the cover 139 to provide a downwardly depending second portion which extends about the evaporator element 1181` `and is securely clamped thereto, as indicated at 171. Since inert gas weak in 'refrigerant first flows in the presence of liquid refrigerant in the evaporator element 118C, liquid refrigerant evaporates at the lowest temperature in this evaporator element. The low temperature cooling effect produced by evaporator element 1181` is transferred to the verticalpart of member 153 which serves to transmit such cooling effect to vthe horizontal part of the member 153 which is positioned in the freezing compartment 11511. Therefore, in the freezing .compartment 11511, an extremely low temperature cooling effect is transmitted to matter which is stored in the upper part of such compartment. Since the evaporator element 118C and ver-r tical part of member 153 are completely embedded in the insulation .138, ,substantially all of the useful. refrigerating effect produced by evaporator element 113e is effectively transmitted to the Vupper part of the freezing compartment. The member 153 effectively cools air owing in intimate contact therewith, such cool air tending to move *downwardly to displace air in the lower part of the freezing compartment which subsequently becomes subjected to the cooling effect of the member 153.

With conventional thermostatic operation of absorption refrigeration apparatus of the inert gas type, heat is supplied intermittently to the generator, the supply of heat being stopped when a desired 10W temperature is reached at the point of control, and being resumed when the temperature tends to rise from the desired value at such point of control. With such conventional thermostatic control, the temperature tends to vary -a-t different regions in the storage space of a refrigerator cabinet. This is due to the fact that the control is usually effected from a single control point in the storage space and the fact that there is a time =lag until an equilibrium condition is reached before the thermostatic control actually becomes effective to change the heat supply to the generator. Under these conditions, there are variations in temperature in different regions of the storage space which are generally acceptable, so long as the peak temperatures do not exceed a predetermined high value.

By providing the member 153 in the embodiment of Figs. 5 and 6 and controlling the heat supply to generator 128, so that heat will continue to be supplied and make liquid refrigerant available in evaporator element 118C, even when the evaporator element 11811 reaches a desired low temperature, a more uniform temperature can be maintained in Val-l regions of the freezing compartment 11511 sand high temperature peaks tending to occur at certain points in such compartment are substantially avoided. I accomplish this by providing a vapor-liquid lift 127 having two lift tubes 12711 and 127b, both of which are in thermal exchange relation with the heating tube 129. The internal diameter of the lift tube 127b is smaller than that of the lift tube Y12711.

Further, the heating element 131 comprises two parts or sections, only one of which is affected by the operation of the thermostatically controlled switch 162. In Fig. 7 it will be seen that electrical energy is supplied to one part ofV heating element 131 through an electrical cir-V cuit which includes conductor 166, manual switch 168, conductor 172 and conductor 167. The circuit just described by-passes the switch 162 so that, when the manually operated switch 168 is closed, electrical energy will always be supplied to one part of the heating element 131. Electrical energy is supplied to the other part of the heating element 131 through l'an electrical circuit which includes conductor 166 and switch 162 connected therein, and conductor 167.

When the temperature of evaporator element 11811 tends to rise above a predetermined `low value, the thermostatic control becomes effective to close switch 162 and electrical energy is supplied to both parts or sections of heating element 131. The liftY tube 12711 is of such size that vapor is expelled from solution therein at a suiciently rapid rate,v when Yelectrical energy is being supplied to both parts or sections of the heating element 131, whereby liquid can be raised therein by vapor ilift action. However, when electrical energy is supplied only to the one part of the heating element 131 and the switch 162 is open, vapor is evolved at a rate insuflicient to cause lifting of liquid by vapor lift action through the lift tube 127:1. The internal diameter of the second lift tube 127b is such that liquid can be effectively raised therein by vapor lift action when the switch 162 is open and electrical energy -is being supplied only to one part of the heating element in the electrical circuit which includes conductors 167 and 172.

In view of the foregoing, it will now be understood that, even when the evaporator'element 118a associated with the bottom plate 154 is at an adequately low termperature and the thermostatic control has operated to open switch 162, electrical energy is still supplied to one part of the heating element 131, whereby lift tube 127 b can continue to lift liquid into the upper part of the standpipe 158 and maintain the refrigeration apparatus in operation to a suicient extent to make liquid refrigerant availableV in the evaporator element 118C. While the quantity of liquid refrigerant made available to evaporator element 118e under these conditions is considerably less than the quantity of liquid refrigerant delivered to the evaporator 118 when both lift tubes 127a and 127 b are functioning, nevertheless the small quantity of liquid refrigerant supplied to evaporator element 118C, when lift tube 127a is ineffective, enables evaporator element 118C to continue to operate Iand transmit cooling effect to member 153. Accordingly, ea more uniform temperature is obtained in all parts of the freezing compartment 115a and high temperature peaks in certain regions in this compartment are avoided.

Modifications of the embodiments of my invention which I have described will occur to those skilled in the art, so that I desire my invention not to be limited to the particular arrangements set forth yand intend in the claims to cover all modifications which do not depart from the spirit `and scope of the invention.

What is claimed is:

l. In a refrigerator having a cabinet provided with thermally insulated wall structure including inner and outer wall members and insulation therebetween, said inner wall member forming an innerliner of a storage space, refrigeration apparatus of the absorption type having v'a gas circuit comprising an evaporator element including conduit means in which refrigerant evaporates in the presence of an inert gas to produce a cooling effect, said conduit means between spaced apart regions in the lengthwise direction thereof having a horizontally extending section which is disposed outside the storage space and completely enveloped in the insulation of said wall structure and out of physical contact with the inner and outer wall members thereof, said inner liner or wall member being apertured, heat transfer means for transmitting cooling effect produced within said conduit section to matter in the storage space solely through a metallic heat iow path, said heat transfer means comprising a metallic member disposed within the storage space and metallic means heat conductively connected thereto which includes a part extending from the storage space through the apertured liner into said insulated wall structure, the section of said conduit means between the spaced apart regions thereof being thermally `connected to said part extending into said wall structure.

2. Apparatus as set forth in claim l in which said metallic member essentially is a at plate and the aperture in said inner liner is of slot-like form.

3. Apparatus as set forth in claim 2 in which said metallic member occupies and takes up a minimum amount of space in a vertical direction and is disposed at the vicinity of the ceiling of the storage space.

4. Apparatus as set forth in claim l in which said `1 metallic member and metallic means are vof sheet-like form and the aperture in said inner of a slot, and insulating means at the aperture of said inner liner for'thermally insulating the latter from said metallic member and metallic means.

5. Structure as set forth in claim l in which said gas circuit includes another evaporator element in which refrigerant evaporates in the presence of the inert gas to produce a cooling effect, said other evaporator element being disposed in the storage space, said metallic member having a relatively extensive heat transfer surface and serving to transfer cooling effect to a region of the storage space which is removed from 4and above said other evaporator element.

6. In a refrigerator having a cabinet provided with thermally insulated wall structure including inner and outer wall members and insulation therebetween, said inner wall member forming an inner liner of a storage space, refrigeration apparatus of the absorption type which includes a gas circuit comprising a first evaporator element having conduit means in which refrigerant evaporates in the presence of an inert gas to produce a cooling effect, said conduit means between spaced apart regions thereof having a section which is disposed outside the storage space and completely enveloped in the insulation of said wall structure and out of physical contact with the inner and outer wall members thereof, said inner liner or wall member being apertured, heat transfer vmeans for transmitting cooling effect produced within said conduit section to matter in the storage space solely through a metallic heat flow path, said heat transfer means comprising a metallic member disposed within the storage space and metallic means heat conductively connected thereto which includes a part extending from the storage -space through the apertured liner into said insuilated wall structure, the section of said conduit means between the spaced apart regions thereof being thermally connected to said part extending into said wall structure, said cabinet comprising wall means providing a low temperature zone in lche storage space and said gas circuit including a second evaporator element in which refrigerant evaporates in the presence of the inert gas to produce a cooling effect, said second evaporator element being arranged to transfer cooling effect to the bottom of said zone, and said metallic member having a relatively extensive heat transfer surface and serving to transfer cooling eifect to said zone at a region which is above said second evaporator element.

v k7. In a refrigerator having Ia lcabinet provided with thermally insulated wall structure including inner and 'outer wall members and insulation therebetween, said inner wall member forming an inner liner of `a storage space, refrigeration apparatus of the absorption type which includes a gas circuit comprising a rst evaporator `element having conduit means in which refrigerant evaporates in the presence of an inert gas to produce a cooling effect, said conduit means between spaced apart regions thereof having a section which is disposed outside the storage space and completely enveloped in the insulation of said wall structure and out of physical contact with the inner and outer wall members thereof, said inner lliner yor wall member being apertured, heat transfer means for transmitting cooling effect produced within said conduit section to matter in the storage space solely through a metallic heat flow path, said heat transfer means comprising Ia metallic member disposed within the storage sp'ace .and metallic means heat yconductively connected thereto which includes a part extending from the storage space through the apertured liner into said insulated wall structure, the section of said conduit means between the spaced lapart regions thereof being thermally connected to said part extending into said Wall structure, said cabinet comprising Wall means providing a freezing compartment in the storage `space and said gas circuit including -a second evaporator element in which refrigerant evapliner is in the form' area-,ser

crates in the presence of the inert gas to produce `a cooling effect, said iirst evaporator elementbeing operable vat a 'lovv temperature and said second evaporator element being operable at a higher tempera-ture, said second evaporator element being arranged to-transfer cooling effect to the bottom part of said freezing compartment, and said metallic member having `a relatively extensive heat transfer surface and serving to transfer -cooling effe-ct to the upper part of said freezing compartment.

8. Cooling structure providing a place of cooling, absorption refrigeration apparatus including an evaporator element and a vapor expulsion unit, means for heating said unit to supply liquid refrigerant to said evaporator element at a normal rate, said evaporator element including conduit means in which refrigerant evaporates to produce a cooling effect, said conduit means between spaced apart regions in the lengthwise direction thereof having a section positioned in a second place out of direct thermal exchange relation with the place of cooling, heat transfer means for transferring cooling effect produced within said conduit section to matter in the place of cooling solely through a metallic heat ow path, said heat transfer means comprising a metallic member disposed within the place of cooling, said metallic member including a part which extends to said second place and is thermally connected to said conduit section, means responsive to temperature for controlling said heating means, said last-mentioned means including provisions for modifying the heating of said unit by said heating means to reduce the supply of liquid refrigerant to said evaporator element from the normal rate and for heating said unit by said heating means to continue supplying liquid refrigerant to said evaporator element at a rate less than the normal rate to render said conduit section of said evaporator element operable to produce cooling effect and said metallic member operable to transfer cooling elfect to the place of cooling.

9. Structure as set forth in claim 8 in which said means responsive to temperature includes provisions for moditying the rate at which said unit is heated by said heating means, when said place of cooling reaches a desired low temperature, to reduce the supply of liquid refrigerant to said evaporator element from the normal rate and for heating said unit by said heating means to continue supplying liquid refrigerant to said evaporator element at a rate less than the normal rate to render said conduit section of said evaporator element operable to produce cooling effect and said metallic member operable to transfer cooling effect to said place of cooling'even when the latter is at the desired low temperature.

10. Structure as set forth in claim 9 in which said absorption refrigeration apparatus includes a gas circuit having said evaporator element and another evaporator element in said place of cooling, and means for initially ilowing liquid refrigerant to said evaporator lelement and from the latter to said other evaporator element for tloW therethrough, said control means being responsive to 11. Cooling structure providing a place of cooling,

absorption refrigeration apparatus including an evaporator anda vaporiexpulsion unit, an absorption'liquid circuitY comprising .said vapor expulsion unit, said circuit having at least two vertically extending'conduits through which liquid is raised from one level to a higher level, means for heating said unit to supply liquid refrigerant to said evaporator at a normal rate, said evaporator being positioned in a second place which is out of direct thermal exchange relation With said place of cooling, a metallic member positioned in said place of cooling for transferring cooling edect therein, said member including a part which extends to said second place and is heat conductively connected to Vsaid evaporator, means responsive to temperature for controlling said heating means, said last-mentioned means including provisions for modifying the rate at which said unit is heated by said heating means, when said place of cooling reaches a desired low temperature, to reduce the supply of liquid refrigerant to said evaporator from the normalrate and for heating said unit by said heating means to supply liquid refrigerant to said evaporator at a rate less than the normal rate to render said evaporator effective to produce cooling effect and said metallic member operable to transfer cooling effect in said place of cooling, even when said place of cooling is at the desired low temperature, one of said vertically extending conduits having a larger internal cross-sectional area than the other and through which liquid iiows only when said unit is heated by said heating means to supply liquid refrigerant to said evaporator at the normal rate.

12. Cooling structure as set forth in claim 11 in which said vertically extending conduits form vapor-lift tubes in which liquid is raised by vapor-lift action, said tube having the larger internal cross-sectional area being effective to raise liquid by vapor-lift action only when said unit is heated by said heating means to supply liquid refrigerant to said evaporator at the normal rate.

References Cited in the tile of this patent UNITED STATES -PATENTS 2,645,908 Backstrom July 21, 1953

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