US2039588A - Refrigeration - Google Patents

Description

May 5, 1936. E. A. FORSBERG REFRIGERATION Filed D60. 51, 1935 2 Sheets-Sheet l INLENTOR.

,1 ATTORNEY.

y 936. E. A. FORSBERG 2,039,588

REFRIGERATION Filed Dec. 31, 1935 2 Sheets-Sheet 2 M INVENTOR. BY W M ATTORNEY.

Patented May 5, 1936 UNITED STATES REFRIGERATION Erik August Forsberg, Stockholm, Sweden, as-

signor, by mesne assignments, to Serve], Inc., New York, N. Y., a corporation of Delaware Application December 31, 1935, Serial No. 56,879 In Sweden August 25, 1933 15 Claims.

This invention relates to refrigeration and more particularly to control of continuous refrigeration produced with the aid of a plurality of refrigeration systems of an intermittent type, and it is an object of the invention to provide an improved arrangement by means of which a more exact control of heat input responsive to the refrigerating requirements and distribution of work between a plurality of systems is effected in a simple and dependable manner.

The invention, together with the objects and advantages thereof, will become apparent upon consideration of the following description taken in connection with the accompanying drawings in which:

Fig. 1 shows diagrammatically a refrigerator embodying the invention; and

Fig. 2 illustrates" a modification thereof.

Referring to Fig. 1, there are shown two absorption systems of an intermittent type. The first system, herein referred to as system A, comprises a generator-absorber I0, a condenser I I, a receiver I2, and an evaporator I3. The generator-absorber I is provided with a suitable heating element as, for instance, an electric heating resistance element I4. The generator-absorber I II is provided with heat radiation fins I5 for air cooling, and is located and vertically movable within a thermally insulated jacket or flue I6 which is open at the bottom. The generator-absorber I0 is connected to the condenser I I by means of a conduit I'I including a flexible portion I8 which permits vertical movement of the generator-absorber within the jacket or flue I6. The condenser I I is provided with heat radiation fins I9 for air cooling. The evaporator I3 is in the form of a coil provided with heat transfer fins, and is located in the upper part of a thermally insulated refrigerator storage compartment 20. Both ends of the evaporator coil I3 are connected to the receiver I2 which is embedded in the thermal insulation around the refrigerator compartment 20. The receiver I2 is connected by means of a conduit 2| to the condenser I I.

It will be understood that the refrigeration system -just described is merely illustrative of this type of system and is shown only diagrammatically for the .purpose of explaining the present invention which is not thus limited. The refrigeration system contains a suitable absorbent such as water in the generator-absorber Ill, and a refrigerant fluid such as ammonia which is soluble in the absorbent. In operation, heat is applied to the generator-absorber ID by connecting the heating element I4 to a source of electricity 22, as

(Cl. 62r-5) hereinafter described. Ammonia vapor is expelled from solution by heating in the generator-absorber, the vapor flowing through the flexible conduit I8 and conduit I! to the condenser II. The ammonia vapor is condensed to liquid in the condenser, and the liquid flows through conduit ZI into the receiver I2 and evaporator coil I3. This process takes place during what is referred to as a generating or heating period. Heating of the generator-absorber I 0 is then discontinued, and the latter is cooled by upward flow of air through the jacket or flue I6. Upon decrease in temperature of the generatorabsorber I0, thepre'ssure in the system decreases due to absorption of refrigerant vapor into solution in the weakened liquid in the generator-absorber, and, when the pressure issufficiently reduced, liquid refrigerant evaporates in the evaporator coil I3, whereby refrigeration is produced. This process continues during a period which may be referred to as a refrigerating or absorbing period. A generating period and an absorbing period constitute a cycle of operation of the system.

The second refrigeration system, herein referred to as system B, is like the previously described system A and comprises a generator-absorber 30, a condenser 3I, a receiver 32, and an evaporator coil 33. The evaporator coil 33 is also located in the refrigerator compartment 20. The enerator-absorber is provided with an electric heating element 34 and heat radiation fins 35, and is also vertically movable within a thermally insulated jacket or flue 36. The generator-absorber 3t is connected to the condenser 3| by means of a conduit 3'! having a flexible portion 38 which permits vertical movement of the generator-absorber within the jacket or flue 36. The condenser 3| is provided with heat radiation fins 39 for air cooling. The evaporator coil 33 is connected to the receiver -32 which is embedded in the thermal insulation around the refrigerator compartment 29, and the receiver is connected by means of a conduit 4| to the condenser 3|.

It will now be understood that continuous refrigeration of the storage compartment 20 may be had by alternating the absorption or refrigerating periods of the two systems A and B, that is, operating the systems so that the generating period of system A occurs during the absorption or refrigerating period of system B, and so that the absorption or refrigerating period of system A may be started at the termination of the refrigerating period of system B. It is desirable that heat input to system A be terminated at the end of a generating period whether or not system B has reached the end of its refrigerating period. It is also desirable that cooling of the generator-absorber ll] of system A be started sufficiently ahead of the termination of the refrigerating period of system B so that the pressure in system A will be sufiiciently reduced to instigate refrigeration immediately upon termination of the refrigerating period of system B. It is further desirable that control of systems A and B be effected during their respective refrigerating periods so that a desired temperature may be automatically maintained in a refrigerator storage compartment 20. This is all accomplished by the control now to be described.

The generator-absorber i0 is mounted on one end of a lever 42 which is suitably pivoted at 43 and the movement of which is limited by suitable stops 44. The weight of the generator-absorber H) is counterbalanced by weight 45 on the other end of lever 42. 46 is arranged on lever 42 so that it moves back and forth across dead-center of the lever system as the generator-absorber I0 moves up and down in the flue l6. When the generator-absorber I0 is in its lower position, as illustrated in Fig. 1. the efiect of weight 46 is added to the weight of the generator-absorber and liquid contained therein. As refrigerant vapor is expelled from solution in the generator-absorber Hi, the latter becomes lighter and rises until the weight 46 moves over dead-center and is added to the counterbalancing weight 45, whereupon the lever 42 moves quickly due to the sudden unbalance, and the generator-absorber I0 is carried to its upper position.

The second generator-absorber 30 of system B is likewise mounted on a lever 52 pivoted at 53 and provided with stops 54. The generatorabsorber 30 is counterbalanced by a weight 55, and the lever 52 is provided with a weight or pendulum 56 which moves back and forth across dead-center as explained in connection with system A in the preceding paragraph.

The electric heating element M in system A is connected by a wire 60 to one side of the source of electrical current 22. The circuit of the heating element I4 is adapted to be completed by means of a wire 6|, electrical contacts 62, wire 63, electrical contacts 64, and a wire 65.

The heating element 34 of system B is connected to one side of the source of electrical cu rent 22 by means of a wire 10. The circuit cf the heating element 34 is adapted to be completed by means of a wire, electrical contacts :g, a wire 13, electrical contacts 14, anda wire The electrical contacts 62 and I4 are part of aswitch operated by the lever 42 of system A, and contacts 64 and 12 are part of a switch uperated by thelever 52 of system B. Thus, the circuit to the heating element I4 is completed only when the generator-absorber I0 is down and the generator-absorber 36 is up, as illus trated in Fig. 1. Assume now that the end of the generating period for system A is reached. Thelightened generator-absorber l0 rises due to the overbalance of weight 46, and lever 42 opcrates to open contacts 62 and close contacts 14. Heating of the generator-absorber I6 is thus discontinued. However, the operation of system B is not aifected. When the generator-absorber "of system B becomes sufllciently weight d, at the end of the refrigerating or absorption period of this system, the lever 52 is operated to open A weight or inverted pendulum contacts 64 and close contacts 12. Thereupon, the circuit of the heating element 34 is completed and the generating period of system B is instigated.

As previously indicated, the generator-absorber In of system A is cooled by upward flow of air through the insulated flue l6. An upper continuation 16 of the flue I6 is provided with dampers 11 and 18. Likewise,an upper continuation 19 of" the flue 36 for system B is provided with dampers and 8|. The dampers I8 and 80 are operated together to regulate the temperature of refrigeration. As shown in Fig. 1, the dampers l8 and 80 are interlocked by means of a rod 82 which is operatively connected by means of a lever 83 to an operating member 84 of a thermostat. The sensitive bulb 85 of the thermostat is located in the refrigerator storage compartment 20 so that the dampers 18 and 80 are operated responsive to temperature in the refrigerator compartment. The dampers 18 and 80 are closed upon decrease in temperature, and opened upon increase in temperature. Thus, flow of air over the generator-absorbers l0 and 30 is controlled so that whichever is operating to produce refrigeration is cooled to the extent necessary to maintain a desired temperature in the storage compartment 20.

The damper 11 in system A is operated by the lever 42, being operatively connected thereto by means of a rod 86, a bell-crank 81, and a rod 88. It will be understood that the operative connection to the damper I1 is such that this damper is closed during the heating or generating period and is opened upon termination of the heating period and remains open until the beginning of the next heating period. The damper 8| in system B is operatively connected by means of a rod 83, a bell-crank 30, and a rod 3| to the lever 52. The damper 8| is thus open except during the heating period of system B. It will now be understood that dampers I1 and 8| cut oi! flow of air over the generator-absorbers Ill and 33 only during the respective heating periods of systems A and B, and at other times leave control of the air flow to the dampers l8 and 83 responsive to temperature in the refrigerator compartment 20.

With the control just described in connection with Fig. 1, the damper TI is opened and cooling of the generator-absorber l0 starts immediately upon termination of the heatingperiod of system A, whether or not system B has yet reached the end of its absorption or refrigerating period. Under certain conditions, therefore, it could occur that the generator-absorber would be sufflciently cooled so that system A would start to produce refrigeration before termination of the refrigerating period of system B. In order to delay cooling of the generator-absorbers until termination of the respective refrigerating periods of the other system, the dampers TI and 8| may be controlled as illustrated in Fig. 2. In this figure, like parts are indicated by the same reference numerals as in Fig. 1. TI and 8| are interlocked by means of a rod 32 having projecting members 33 and 34. The rod 36 is connected between the lever 42 and a bellcrank 35. The rod 3| is connected between the lever 52 and a bell-crank 36. The bell- cranks 35 and 36 are operatively associated respectively with the projections 34 and 33 in a manner to each move the rod 32 in one direction only. The bell-crank 35 operates to move the rod 32 to close damper I1 and open damper 8|. The bell-crank The dampersl8 operates the rod 92 to close damper 8| and open damper TI. It will now be understood that, at the .end of the heating period of system A, the dampers l1 and 81 will not be operated, and cooling of the generator-absorber III will not begin except as it may cool slowly by radiation which is retarded by the insulated jacket or flue Ii, However, when system B reaches the end of its absorption or refrigerating period, damper 8| will become closed and damper l1 opened, thereby placing the cooling of the generator-absorber It under the control of the thermostatically operated damper 18.

It will he understood that various modifications and changes may be made within the scope of the invention which is not limited to that which is shown in the drawings and described in the specification but only as indicated in the following claims.

What is claimed is:

1. A refrigerator including a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, a heater for each of said systems, and means for automatically controlling operation of said systems including shutting off a heater at the end of a heating period of the respective system without affecting operation of another of said systems.

2. A refrigerator including a plurality of intermittent absorption refrigeration systems having aliernate heating and refrigerating periods, a heater for each ,of said systems, and means for automatically controlling operation of said system including shutting off a heater of a respective system prior to termination of a refrigerating period of another of said systems so that cooling of said first system may occur and said upon termination of a refrigerating period of said second system.

3. A refrigerator including a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, a heater for each of said systems, means for automatically controlling operation of said systems including shutting off a heater at the end of a heating period of the respective system without affecting operation of another of said systems, and means for delaying cooling of said first system so that it will not start to produce refrigeration until termination of a refrigerating period of said second system.

4. In a process of continuous refrigeration with the aid of a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, that improvement which consists in terminating a heating period of one of said systems responsive to a condition in said system without affecting operation of another of said systems.

5. In a process of continuous refrigeration with the aid of a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, that improvement which consists in terminating a heating period of one of said systems responsive to a condition of said system occuring prior to termination of a refrigerating period of another of said systems whereby cooling of said first system may commence and said first system be ready to produce refrigeration upon termination of the refrigerating period of said second system.

6. In a process of continuous refrigeration with the aid of a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, that improvement which consists in terminating a heating period of one of said systemsresponsive to a condition of said system occurring prior to termination of a refrigerating period of another of said systems and retarding cooling of said first system so that it will not produce refrigeration'until termination of a refrigerating period of said second system.

7. A refrigerator including a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, each system including a generator-absorber, means for heating said generator-absorber, means for cooling said generator-absorber, and means for alternately operating said heating and cooling means constructed and arranged so that said heating means is shut off without affecting operation of another of said systems.

8. A refrigerator including a plurality of intermittent absorption refrigeration systems having alternate heating and refrigerating periods, each system including a generator-absorber, means for heating said generator-absorber, means for cooling said generator-absorber, means for alternately operating said heating and cooling means constructed and arranged so that said heating means is shut off without affecting operation of another of said systems, and means for regulating operation of said cooling means to maintain a desired temperature in the refrigerator.

9. A refrigerator including two intermittent absorption refrigeration systems each including a generator-absorber, means for heating said generator-absorber, and means for'cooling said generator-absorber, and means for alternately operating the heating and cooling means of each of said systems constructed and arranged so that the heating means of one of said systems is shut off without affecting operation of the other system and cooling of said first system is retarded until termination of a refrigerating period of said second system.

10. A refrigerator including two intermittent absorption refrigeration systems each including a generator-absorber, means for heating said generator-absorber, and means for cooling said generator-absorber, means for alternately operating the heating and cooling means of each of said systems constructed and arranged so that the heating means of one of said systems is shut off without affecting operation of the other system and cooling of said first system is retarded until termination of a refrigerating period of said second system, and means for regulating operation of said cooling means to maintain a desired temperature in the refrigerator.

11. In a refrigerator having a compartment to be cooled, two intermittent absorption refrigeration systems each including a cooling element in said refrigerator compartment, a condenser, agenorator-absorber, a heater for said generator-absorber, a conduit for conducting fluid for cooling said generator-absorber, a first valve for controlling fiow of fluid in said conduit, andasecond valve for opening and closing said conduit, a thermostat for regulating said first valve of both systems to maintain a desired temperature in said compartment, a supply line for each heater including two control devices in series, and means associated with each system operative at the end of each period in the cycle of operation of the respective system to operate one of said two control devices in the heater supply line of the respective system and operate one. of the two control devices in the heater supply line of the other system and close said second valve of the respective system at the end of the absorption period.

12. In a refrigerator having a compartment to be cooled, two intermittent absorption refrigeration systems each including a cooling element in said refrigerator compartment, a condenser, a generator-absorber, an electric heating element for said generator-absorber, a conduit for conducting fluid for cooling said generator-absorber, a first valve for controlling flow of fluid in said conduit, and asecond valve for opening and closing said conduit, a thermostat for regulating said first valve of both systems to maintain a desired temperature in said compartment, an energizing circuit for each heating element including two switches in series, and a control device associated with each system, said control device being operative at the end of each period in the cycle of operation of the respective system to reverse one of said two switches in the heating circuit of the respective system and one of the two switches in the heating circuit of the other system and reverse said second valve of the respective system.

13. In a refrigerator having a compartment to be cooled, two intermittent absorption refrigeration systems each including a cooling element in said refrigerator compartment, a condenser, a generator-absorber, a heater for said generatorabsorber, means for cooling said generator-absorber, a first device for regulating said cooling means, and a second device for stopping operation of said cooling means, a thermostat for operating said first device of both systems to maintain a desired temperature in said compartment, and a control device associated with each system, said control device being operative at the for said generator-absorber, a conduit for con ducting fluid for cooling said generator-absorber, a first valve for controlling flow of fluid'in said conduit, and a second valve for opening and closing said conduit, a thermostat for regulating said first valve of both systems to maintain a desired temperature in said compartment, an energizing circuit for each heating element including two switches in series, and a control device associated with each system, said control device being operative at the end of each heating perfld in the cycle of operation of the respective system to open one of said two switches in the heating circuit of the respective system and close one of the two switches in the heating circuit of the other system, and said control device being operative at the end of each absorption or refrigerating period in the cycle of operation of the respective system to close said switch in the heating circuit of the respective system and open said switch in the heating circuit of the other system and close said second valve of the respective system.

15. In a refrigerator having a compartment to be cooled, two intermittent absorption refrigeration systems each including a cooling element in said refrigerator compartment, a condenser, a generator-absorber, an electric heating element for said generator-absorber, a flue for conducting air in cooling relation to said generator-absorber, a flrst damper for controlling flow of air in said flue, and a second damper for opening and closing said flue, a thermostat for regulating said first damper of both systems to maintain a desired temperature in said compartment, an energizing circuit for each heating element including two switches in series, and a control device associated with each system, said control device being operative at the end of each heating period in the cycle of operation of the respective system to open one of said two switches in the heating circuit of the respective system and close one of the two switches in the heating circuit of the other system, and said control device being operative at the end of each absorption or refrigerating period in the cycle of operation of the respective system to close said switch in the heating circuit of the respective system and open said switch in the heating circuit of the other system and close said second damper of the respective system.

I nan: AUGUST FORSBERG;

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