US2239583A - Refrigerating system - Google Patents

Description

April 22, 1941. i w. H. F. SCHMIEDXNG 2,239,583

REFKIGERAfII-NG SYSTEM v Filed July '1, 19:58 4 Sneets-Sheot 2 I A ril 22, 1941. w. H. F. SCHMIEDING REFRIGERATING SYSTEM Filed July 7, 1938 4 Sheets-Sheet 3 Jig 7 ,(mv o April 1941- w. H. F. scumzumd 2, 39,583

REFRIGBRATING SYSTEM Filed Jul '7, 1938 4 Sheets-Sheat 4 Ark. m2 "3 of theinvention;

Patented Apr.

i UNITED STATES" PATENT. OFFICE I i nnraicsi ati izc i srs'rnm Warren H. F. Schmieding, Columbus, Ohio Application 7, 1938, Serial N0. 217,873

The present invention relates to refrigerating systems wherein a plurality of heat absorbers are associated with a single heat dissipator for cooling the absorbers and particularly to that type of system in which one of the heatabsorbers is maintained at a relatively cold temperature for freezing or storing frozen products and the other is maintainedat a relatively higher temperature 1 in response to a demand for refrigeration on the relatively cold heat absorber.

Fig. 7 is a cross sectional view of one of the valvesemployed in Fig. 6; and

' 23 and 2| and a heat -dissipator 22. The heat Another object of the present invention is to 7 provide a refrigerating system utilizing a plurality of evaporators connected in series circuit relation andcontrolling the pressure differential between the evaporators in response to a demand for refrigeration on the relatively cold evaporator.

of the evaporators when it is desirable to remove absorbers are herein shown as evaporators and the heat dissipator includes a compressor 24 which is driven by a motor 25 and belt 26. The heat dissipator also includes an air cooled condenser 23 which is connected with the high pressure side of the compressor by a pipe 29. Liquid refrigerant is conveyed to pressure reducing valves 3i and 32 by a pipe 33. The pressure reducing valves each include a casing 35 containing a float 36 which actuates a needle valve 31. When a predetermined amount of liquid is contained within the casing 35, the float 36 rises oil of its seat 38 and admits liquid refrigerant in the case of valve 3i, to pipe 43 and, in the case of valve 32, to the pipe 4|. The pipe 40 is connected to the header 43 of evaporator 20 and the pipe 4! is connected to the header':.44 of evaporator 2|. The evaporators are'preferably of the sheet metal type now generallyused in'the refrigerating industry-and include two sheets of metal hermetically joined with one another, one of which being corrugated whereby to provide a plurality of ducts extending horizontally from either header 43 or header 44 and vertically to the frost therefrom.

reducing valve employed in the system shown inFig, 1;

' to the low pressure side of the compressor 24.. Gaseous refrigerant is withdrawn from evapoi headers 45 and 41 of evaporators 20 and 2!, respectively. Gaseous refrigerant is withdrawn from evaporator 20 through pipe. 43 which is connected with header 46. This pipe 43 is connectedby a coupling 49 to a pipe 53. The pipe.

50 is connected to a vaporizing chamber or surge tank 5i and this tank is connected by a pipe '52 rator 2| by a pipe which is connected with the outlet header 41. This gaseous refrigerant flows through a valve 55, whence it flows by a pipe to the coupling 45 and from coupling 43 it flows by way of pipe 55; tank 5| and'pipe 52 to the low pressure side of compressor 24.

Fig.3 is a cross sectional view of another con- I Fig. 6 is a. diagrammatic view-of another form of the invention;

- The valve 55 is adapted to. at times, impede ing a passage 53 for receiving refrigerant from pipe 54 and: a passage 53 is controlled by a valve 5!. This valve is actuated by a diaphragm 63 contained in a chamber 54. when the valve is as closed the flow of refrigerant from evaporator 2| is stopped. It may be desirable, however, to permit a small quantity of gaseous refrigerant to escape from evaporator 2| and for this purpose I have. provided a restricted by-pass 65 which interconnects passage 59 with the passage 60 so that a limited amount of refrigerant may be withdrawn from evaporator 2| although valve 6| is closed. The valve BI is actuated by a thermostatic system 66 including a bulb 61 and pipes 68 and 69 connected by a coupling I0.

- This thermostatic system also includes the chamber 64. The thermostatic system contains a volatile fluid and the charge is such that when the bulb is at or above 32 deg. F., the pressure in the system is sufficient to collapse the diaphragm 63 and close the valve 6| on its seat.

Thus it is apparent that when warm foods or water, adapted to be frozen, are placed within the storage chamber 1| of evaporator 20, the thermostaticsystem 66 will function to stop or impede the flow of gaseous refrigerant from evaporator 2|. In that event the withdrawing action of .the compressor will be concentrated or primarily concentrated on withdrawing gaseous refrigerant from evaporator 20. This will continue until the evaporator 20 and the food stored therein have been reduced to the desired low temperature at which time the pressure will hereducedin the thermostatic system 66 to open the valve 6| whereby the refrigerating system will be returned to normal operation.

It is desirable to normally maintain the evaporator 2| above the temperature of evaporator 20, the purpose being to maintain the evaporator 2| merely slightly below the desired temperatur of the airand the foodproducts so as to limit or substantially prevent dehydration of the food products such as vegetables' This normal differential in temperature between evaporator 20 and 2| is obtained by making the evaporator 2| much larger than the evaporator 20, insulating the evaporators from one another by insulation 13 and providing a restriction I2 in outlet pipe 54 of evaporator 2|.

Preferably the temperatures are controlled by thermostatic control system 14 including a bulb I5, a diaphragm I6 and snap acting mechanism 11, which controls the switch 18. The switch I8 controls the starting and stopping of the motorporized refrigerant from evaporator 2| to evaporator 20 will be stopped or impeded to such an extent that substantially no condensation will take place in evaporator 28. When this occurs the evaporator, 21 will increase in temperature rapidly. When the temperature of the air within the compartment 84 increases: beyond that desired, thermostatic system I4 will function to close the switch I8 to start the compressor 24. Preferablythe bulb I is connected in intimate metallic contact with the wall of the evaporator so as to be responsive to the temperature thereof. Thus it is apparent thatwhen warm food is contained within evaporator and there is a demand for refrigeration by evaporator 20, the thermostatic system I4 will function to start the compressor.-

If desirable another thermostatic system 86 may be employed which will include in part, thermostatic system 66 for valve 6|; namely, it will include bulb 61, pipe and coupling I0 and will also include a pipe 81, a diaphragm 88 which actuates snap acting mechanism 89 for actuating a switch 90. This switch 90is connected in parallel with switch I8. It is: arranged to directly close the motor circuit when the bulb 61 functions to close valve 6 I. The thermostatic system I4 will maintain the compressor operative until the temperature of the evaporator 2| has been decreased to its desired normal low temperature and it is quite apparent'that this relatively low temperature will not be attained until the demand for refrigeration on evaporator 2|) has been satisfied because, until the demand on evaporator 28 is satisfied, the valve 6| will be maintained closed, and due to the fact that the compressor is concentrating or substantially concentrating on evaporator 20, the evaporator 2| will not be reduced to desired temperature until evaporator 20 is satisfied. If thermostatic system 86 is also employed, thermostatic system I4 will nevertheless maintain the compressor in operation until evaporator 2| has been satisfied.

Thus it is apparent that thermostatic system 86 may be omitted for thesake of reduction in cost of the apparatus. It does, however, have the effect of starting the compressor quickly in response to a demand for refrigeration by evaporator 20.

From the foregoing it will be seen that the evaporators 20 and 2| are maintained at the desired temperatures substantially at all times and that evaporator 2| will not ordinarily be reduced Y to a temperature which is too cold for the proper preservation of food products such as vegetables even though there is an extensive demand on evaporator 20 which would require a continuous or substantially continuous operation of comous refrigerant from evaporator 2| is stopped or impeded to such an extent that the temperature throughout will not be reduced beyond that normally desired.

The compartment 'II of evaporator 20 is preferably divided, into a food storage compartment 92 for frozen foods and an ice freezing compartment 93.

In the embodiment illustrated in Fig. 4 one part .of a secondary system which is cooled by evaporator I20. In this embodiment the evaporator I28 is constructed similar to evaporator 20 and evaporator |2I is similar torevapo'rator 2| ,except that the upper header I4'I of the evaporator I2| extends downwardly merely for convenience. In this embodiment the well known v resister type pressure reducer |3I is employed comprising a long spiral having a very small inside diameter. Refrigerant is withdrawn from the upper header I46 to the low pressure side of the compressor 24 by a pipe I48 and the condensed refrigerant from condenser-receiver I28 is conducted by the pipe I33 to the restrictor I8I. Like in Fig. l, the evaporator I28 is the low temperature evaporator for freezing water and storing frozen foods and is supported in insulation I13. The secondary system includes a condenser I50 which is in intimate heat exchange relation pressor 24. During this period, the flow of gase-' of the heat absorbers I20 is illustrated as an. evaporator and the other heat absorber I2| is e of the compressor.

with a side wall of evaporator I20. The condensed refrigerant flows from the low part thereof by a pipe II to a valve I55 and the outletof the valve I55 is connected with the header I44 of evaporator I2I. The inlet of condenser I50 is connected by apipe I50 to the outlet header I41 of the evaporator I2I. The valve I55 is substantially the same as valve 55 of Fig. 1 except that it is inverted. It includes a valve body I50 forming passages I50 and I60 which are controlled by a valve I6I actuated by a diaphragm I63. This diaphragm I63 is contained within a closed chamber I64 and is actuated by a thermostatic system I66 including a bulb'I01, and a pipe I60, which is connected with the chamber I64. The bulb I61 is disposed within the storage compartment I1I of evaporator I and if desirable it may be placed in intimate metallic contact with an ice tray'support I12.

- When warm water or relatively warm food is placed in the compartment "I, the volatile fluid in the thermostatic system I66 will expand and cause the valve .I6I to close to impede or stop the flow of liquid in condenser I50 to the header I4'4-of evaporator I2I. when circulation through the secondary system is'stopped or impeded, less heat will be withdrawn from the condenser I50 to'the evaporator I20 and therefore the evaporator I20 concentrates its cooling eflect'upon the products stored within the compartment "I.

In this system, like that shown in Fig. 1, the motor is started and stopped by the closing andopeningof a switch 10 which is controlled by the same type of thermostatic system 14 as is employed inFig. 1. When the temperature of the evaporator I2I attains a predetermined high value the switch 10 will be closed and remain closed untfl the evaporator is cooled to a predetermined low value; When there is a demand for refrigeration by evaporator. I20, the valve I55 will be closed or the flow of refrigerant therethrough will be impeded causing the temperature of evaporator I2I to increase to start the motor. "When the demand from evaporator I20 is satisfiechvalve I55 will be opened widely and the refrigerating system will be maintained operative until temperature of evaporator I2I is satisfied at which time, it will operate to stop the motor. If desirable, valve I55 may be provided with a restricted by-pass I65 interconnectto a pressure reducing valve 232 whence it flows by pipe 2 to the header 244 of evaporator 22I. The refrigerant first passes through evaporator 22I to its header 241 whence it flows by a pipe 239 through a pipe 240 and empties into the header 243 of evaporator 220. Refrigerant after passing through evaporator 220 flows from the header 246 through a pipe 240 to the low pressure side Preferably the valve mf' differential type, that is it includes a casing 235 containing a weighted valve 231. Pressure in the through a pressure reducing valve 23I.

mates high pressure side lifts the valve off its seat to permit the flow of liquid refrigerant from the pipe 230 to pipe, 24I.- When the differential in pressure in pipe 203 is at a predetermined value with respect to the pressure within the evaporator 22I, the weighted valve 231 is lifted off its seat to admit more refrigerant to the evaporator 22I. I I

, Valve 23I. is also of the pressure differential type and one form thereof is shown in Fig. 'l in which the'casing 250 is connected with pipes 230 and 240. A passage 250 is connected with the pipe 239 and the flow of refrigerant through the passage iscontrolled by a ball valve 26I. This ball valve 26I is weighted by upper and lower discs 264 connected with one another by three spacers 265. Valve 26I is lifted ofi its seat by pressure within thepipe 239 and the pressure at which valve" 26I is opened is controlled by the weight of valve 26I the discs 264.and spacers 265 as one factor and pressure of a thermostatic system 266 as another factor. This thermostatic system 266 includes a bulb 261, a pipe 268 and a bellows type diaphragm 263. .An increasev in pressure in the thermostatic system 266 causes an increase in. the closing pressure of the valve 26I, the force being transmitted from the bellows 263 to-the top of the uppr disc 264 through a spring 210. The valve 23I is balanced for changes in pressure within the low pressure side of the valve by a second bellows 214 and a spring 215 which latter is interposed between the bellows 214 and the lower disc 264. Thus it is apparent that the valve 26I is notaflected by mere change in the pressure'in the low pressure side of casing 250 but raised off its seat by an increase in pressure differential between the pressure above and below the valve. This pressure differential is varied by the pressure'in the thermostatic system 266.

Obviously since the pressure within the evaporator 220 is less than the pressure in evaporator 22I and the inner evaporator 220 is insulated by insulation 213 the former is maintained relatively colder. The valve is so adjusted thatevaporator 22I is maintained considerably above freezing temperature while the evaporator 220 is maintained below water freezing temperature.-

When warrn water or unfrozen foods are placed within the compartment 21I of evaporator 220,

thermostatic system 266 will function to in- 1 pressure and temperature within evaporator 22I will be increased. e e

Like'in Figs. 1 and 4 the motor is controlled by a thermostatic system 14 which actuates a' switch 10. 'This switch 10 includes a thermostatic bulb 15 placed in intimate heat exchange relation with the evaporator 22I. It is apparent therefore that when relatively warm products are is of the pressure 220 and since the refrigerating effect of evaporator 22I is decreased the thermostatic system '14 will not function to shut off to interrupt the motor circuit until after the demand on evaporator 220 has first been satisfied and then only 'after the evaporator 22I has been reduced to its er 346 the refrigerant flows by a pipe 339' through a valve 355 and pipe 348 to the header 344 of evaporator 32!. of evaporator 32! is connected by the pipe 348 to the low pressure side of the compressor. The inner evaporator 320 is insulated from the outer evaporator 32! by insulation 313 and since it is insulated and since it is the first to receive the liquid refrigerant, it is maintained at a relatviely colder temperature than the evaporator 32!. The construction of the arrangement is such that normally evaporator 32!! is maintained below freezing temperature while evaporator 32! is maintained slightly below the temperature of the surrounding air and the temperature of the food to be refrigerated.

Due to the fact that" evaporator 320 is maintained at a relatively low temperature, moisture from the air and food stored therein will condense upon the walls thereof and the evaporator will become frosted and impair the efllciency thereof. Therefore it is desirable to, at times, defrost evaporator 32!) and a valve 355 is provided for this purpose. In the embodiment illustrated the valve is in its defrosting position in which itwill be seen that the liquid refrigerant will flow through a conduit which by-passes; the restrictor 33!. This by-pass includes a pipe 359 and a pipe 362. The pipe 359 is also connected with the pipe 333 and the pipe 362 is also connected with the header 343 of evaporator 328.

The flow of refrigerant from passage 360 and 36! is controlled by a valve 364. This valve is carried by a rod 318. Rod 31!) is coupled with a rod 31! having a pull knob 312 thereon. A spring coupling is interposed between rod 31! and 310 including a spring 313 which normally urges the rod 310 to the right when the valve is I in the position shown.

' The valve 355 also includes a chamber 315 which is separated from chamber 36! by a diaphragm 316. The valve 355 also includes a chamber 311 which is sealed from the exterior and to rod 316 by a diaphragm 316. The flow of refrigerant from chamber 311 to chamber 315 is also controlled by the valve 364, that is when the chambers 360 and 36! are in communication, the passage between chambers 311 and 315 is closed, and vice versa, when the valve is in the opposite position. The rod 31! carries an abutment 319 and a spring 389 is interposed between the abutment 319 and an end wall of the valve 355 d normally urges the rod 31! to the left.

The rod 31! is held in the position shown by a.

latch 382. When the latch 382 is withdrawn, the spring 389 forces the rod 31! and the rod 310 to the extreme left whereby the passage between chambers 360 and 36! is closed and the passage between chambers 311 and 315 is opened.

A thermostatic system 366 is employed for releasing, the latch 332. .This thermostatic system includes a bulb 361 and a diaphragm contained The outlet header 341 within housing 363. The housing 363 is connected with the bulb 361 by a pipe 368.

When the valve is in the position shown; namely, in the defrosting position, the high pressure refrigerant will flow from the condenser receiver 328 through pipes 333 and 359, chambers 368 and 36! and pipe 362 to the header 343 of evaporator 320. The refrigerant will first flow through the evaporator and out of the header 346 thence into the pipe 339 whence it will flow by a pipe 384 through a restrictor type pressure reducer 332 and into the header 344 of evaporator to be melted. It will also be noted that at this.

time refrigerant cannot pass through the bypass including the lower part of pipe 339, chambers 311' and 315 of valve 355 and pipe 344 but must flow through the restrictor 332.

The thermostatic system 366 contains a freezing substance such as water within the bulb 361 and oil within the pipe 368 and the chamber 363. When the ice within bulb 361 melts, the pressure will be decreased within the thermostatic system causing the latch 382 to be released whereby the spring 38!] will cause the valve 364 to close the passage between chamber 368 and 36! and open the passage between chambers 311 and 315 whereby the system will be reduced to normal.

The evaporator 32!! may be defrosted by merely pulling outwardly on the knob 312 and the latch 382 will hold the rods 310 and 31! in the position shown. The defrosting operation will take place quickly in view of the fact that the ice will be melted by the heat of the high pressure refrigerant. In other words, during the defrosting operation the quick freezing evaporator 32!] functions as a condenser for a refrigerating system in which the air cooling type of evaporator is the other evaporator of the system. When the ice is melted, the pressure will be reduced in thermostatic system 366 and the latch 382 will be retracted. Thus the system is returned to normal automatically.

A thermostatic system like 86 of Fig. 1 may be employed for starting and stopping'the compressor in accordance with the temperature of the low temperature evaporator 328. In the preferred embodiment the compressor motor 25 is controlled by a thermostatic system 14 like that shown in Fig. 1.

While the forms 'of embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow:

1. A refrigerating system comprising in combination, a plurality of heat absorbers, one of which provides a relatively low temperature for freezing and storing frozen products and another provides a relatively higher temperature for maintaining poducts above freezing temperature, a heat dissipator associated with the heat absorbers for removing heat from the latter including a fluid conduit continuously open while the heat dissipator is operating for the circulation of refrigerant through the second mentioned heat absorber, means responsive to a temperature slightly above 32 Deg. F. of the environment affected by the first mentioned heat absorber for varying the rate of removal of heat units fromthe first mentioned heat absorber.

2. A refrigeratin system comprising in combination, a plurality of heat absorbers, one of which provides a relatively low temperature for freezing and storing frozen products and another I provides .a relatively higher temperature 'for maintaining products above freezing temperature, a heat dissipator associated with the heat absorbers for removing heat from the latter including a fluid conduit continuously open while the heat dissipator is operating for the circulation of refrigerant through the second'mentioned heat absorber, means responsive to. a tempera ture slightly above 32 Deg. F. of the environment affected by the first mentioned heat absorber for increasing the removal of heat units from the first mentioned heat absorbers and decreasing the removal of heat units from the second mentioned heat absorbers.

13. A refrigerating system comprising in combination, aplurality of heat absorbers, one of which provides a relatively low temperature for.

freezing and storing frozen products and another maintaining products above freezing temperature, a heat dissipator associated with the heatabsorbers for removing heat from the latter including a fluid conduit continuously, openwhile provides a relatively higher temperature for l .the heat dissipator is operating for thecirculaslightly above 32 Deg. F. of the first mentioned heat absorber for varying the effects of the heat absorbers. t

. 4. The method-of refrigeration which consists in-withdrawing heat from a plurality of evaporators by a heat dissipator at such rates that one tion of refrigerant through the second mentioned heat absorber, means responsive to a temperature above water freezing temperature, and increasing the rate of volatilization in the first mentioned evaporator by restricting circulation of refrigerant through the secondmentioned evaporator in response to an increased demand for refrigeration on the first mentioned evaporator.

8. The method of refrigerating in that type of system in which a freezing type heat absorber and an air cooling type heat. absorber are em-- ployed and in which it isldesirable to defrost the freezing type heat absorber at times, which methconnectedin series, a regulating valve for con-' trolling the flow of refrigerant from the air cooling type evaporator to the freezing type evaporator, means for withdrawing gaseous refrigerant from the freezing type evaporator and for condensing the refrigerant and for delivering the same to the air cooling type evaporator, pressure reducing mechanism between said means and said air cooling type evaporator, and means responsive to the temperature of the environment affected by the freezing type evaporator for controlling said regulating valve. a

10. A refrigerating system comprising in combination, a heat dissipator, a freezing type heat absorber and an air cooling type heat absorber connected in parallel circuit relation with respect to one another and each in series circuit relation of the evaporators is reduced to below water freezing temperature and the other is maintained, at least part of the time, above water. freezing temperature, and increasing vaporization inthe first mentioned evaporator while vaporizing liquid refrigerant in-the second mentioned evaporator and decreasing vaporization in the second mentioned evaporator in-re'sponse to an increased demand for refrigeration on the first mentioned evaporator.

5. The method asdeflned in claim 4 including the step of decreasing vaporization in the first mentioned evaporator when the increased demand for refrigerationis satisfied. I, I 6. The method of refrigerationwhich-consists in withdrawing heat from a plurality of heat absorbers by a heat dissipator, having a limited capacity, at such rate that one of the heat absorbers is reduced to below water freezing .temperature and the other is maintained, at least part of the time, above water freezing temperature, and concentrating the withdrawing effect of the heat dissipator upon the first mentioned with respect to' the heat dissipator, means for varying the rateof flow of refrigerating medium through the air cooling type heat absorber, and

. means responsive to temperature of the environment afiected by the freezing type heat absorber for actuating the first mentioned means.

.11. A refrigerating system comprising in combination, a heat dissipator, a freezing type heat absorber and an air cooling type heat absorber connected in series circuit relation with one ana other and with the heat dissipator, means for controlling the flow of refrigerating medium from one to the other of said heat absorbers and means I responsive to temperature of the environment effectv by the freezing type heat absorber for actuating the first mentioned means.

' 12. A refrigerating system comprising in com bination, a heat dissipator, a freezing type heat absorber and an air cooling type heat absorber connected in series circuit relation with one another and with the heat dissipator, means for varying the flow of refrigerating medium through the aircooling type heat absorber, and means heat absorber by restricting the withdrawing effect of the heat dissipator upon the second mentioned heat absorber in response to an increased demand for refrigeration on the first mentioned heat absorber.

'7. The method of refrigeration which consists in vaporizing volatile refrigerant in a pluralltyof evaporators by'a refrigerant circulating and heat dissipating means, having a limited capacity, at such rate that one of the evaporators is reduced to below water freezing temperature, and

the other is maintained, at least part of the time,

responsive to temperature of the environment afi'ectedby the freezing type heat absorber ,for actuating the first mentioned means.

13. A refrigerating system comprising in combination, a freezing type heat'absorber and an air coolingtypeheat absorber, a heat dissipator associated with the absorbers for reducing the freezing type heat absorber to below 32 deg. F.

and for maintaining the air cooling type heat absorber, at. least at times, above 32 deg. F., means for varying the rate of fiow of refrigerating medium through the air cooling type heat absorber, and means responsive'to temperature sition, connecting the absorbers with the heat cooling type evaporator; pressure reducing means at the inlets of each of said evaporators; a bypass for each of the means; valve means having dissipator for causing cooling of the absorbers, 10

- and when in the other position, connecting the absorbers in series with one another and in series with the heat dissipator','said last connection providing a path for the flow of refrigerant to the freezing type absorber at a temperature above 5 32 deg. F. for heating the said freezing type absorber; and means responsive to the temperature of the environment affected by the freezing type absorber for actuating the valve means.

15. A refrigerating system comprising in combination, a freezing type vaporator; an air cooling type heat absorber; a heat dissipator assoelated with the aforementioned elements for reducing the temperature of the evaporator to below 32 deg. F. and for maintaining the heat absorber, at least at times, at a temperature above 32 deg. F.; and means for varying'the refrigerating effect of the evaporator including a valve for varying the rate of flow of refrigerating medium two positions, said valve means, when in one position, connecting the evaporators in series circuit relation with one of the by-passes open and the other closed, said valve means, when in another position, connecting the evaporators in series circuit relation with the first mentioned by-pass closed and the second mentioned. bypass open,'-means for withdrawing refrigerant from .the evaporator last to receive refrigerant and for compressing the same and for delivering compressed=refrigerant to the evaporator first to receive refrigerant; and means for controlling theyalve means.

18. The method of refrigeration in that type 'of system employing a freezing type heat absorber and an air cooling type heat absorber which method consists in circulating a refrigerating medium through the heat absorbers at such rate that the freezing type heat absorber is reduced to below water freezing temperature and the air cooling type heat absorber is maintained, at least part of the time, above water freezing temperature, maintaining the air cooling type heat absorber at substantially normal temperature and simultaneously defrosting the freezing type heat absorber by continuing the circulation of refrigthrough the absorber, and a thermostatic device responsive to the environment afiected by the evaporator for controlling the valve.

16. A refrigerating system comprising in combination, a freezing type evaporator and an air cooling type evaporator, said evaporators being connected in series, pressure reducing means connected withthe inlet of the air cooling type evaporator, a second pressure reducing means interposed between the outlet of the air cooling type evaporator and the inlet of the freezing type 40 17. A refrigerating system comprising in combination, a freezing typeevaporator and an air erant medium through the air cooling type heat absorber while causing the heated refrigerating medium to flow through the freezing type heat absorber. i

19. The method of refrigeration which consists a demand for such temperature on saidother evaporator.

20. The method as defined in claim 19 including the step of decreasing the rate of heat absorption by the first mentioned evaporator when gm; increased demand'. for refrigeration is satis- WARREN H. F. SCHMIEDING.

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