US2146796A - Refrigerating apparatus - Google Patents

Description

Feb. 14, 1939. D E. DASHER 7 2,146,796

REFRIGERATING APPARA'IYUS Original Filed May 25, 1934 2 Sheets-Sheet 1 Feb. 14, 1939. D. E. DASHER REFRIGERATING APPARATUS 2 Sheets-Sheet 2 Original Filed May 25, 1954 Patented Feb. 14, 1939 UNITED STATES REFRIGERATING APPAnA'rUs Don E. Dasher, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application May 25, 1934, Serial No. '{27,514 Renewed May 12, 1937 4 Claims. (01. 62-129) This invention relates to refrigerating apparatus and more particularly to two temperature refrigerating systems.

Heretofore, household refrigerators and air 5 conditioners employing but a single refrigerating system, have had evaporating means operating at a single evaporating'temperature and pressure range. In these and other compression refrigerating systems, the pressure energy of the liquid refrigerant in flowing from the high side to the low side of the system, has not been used and has gone to waste.

It is an object of my invention to make use of this pressure energy to create other evaporating pressures for providing a more efliclent refrigerating process and apparatus.

It is another object of my invention to provide an improved type of multiple temperature refrigerating system capable of maintaining a plurality of evaporating pressures without a loss of efflciency wherein only-one suction line is required to connect the compressor with the evapcrating means for withdrawing evaporated refrigerant.

It is a further object of my invention to provide an improved and'more efflcient refrigerating system for household refrigerators andair conditioners employing a plurality of evaporators operating at different evaporating pressures and 30 temperatures and to provide an improved refrigerant control in which a controlled flow of liquid refrigerant is provided from one evaporator to another.

Further objects and advantages of the present 35 invention will be apparent from' the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 isa diagrammatic view of a two temperature household refrigerator and refrigerating system embodying my invention.

Fig. 2 is another diagrammatic view of a two temperature household refrigerator and refrig- 5 crating system embodying another form of my invention.

Fig. 3 is a diagrammatic view illustrating a two temperature air conditioning unit and refrigerating system embodying my invention; and 50 Fig. 4 is a diagrammatic view of a two temperature air conditioning and refrigerating system' embodying another form of my invention.

Referring to the drawings, and more particularly to Fig. 1, there is shown diagrammatically 55 an insulated refrigerator cabinet 20 having an insulated freezing compartment 2| containing a freezing or low temperature evaporating means 22 and an insulated'food storage compartment 23 containing a high temperature evaporator 24.

The evaporators 22 and 24 are supplied with 5 liquid refrigerant by a refrigerant liquefying apparatus including a compressor 25 for compressing the refrigerant and for pumping the compressed refrigerant into a condenser 26 where the compressed refrigerant is liquefied and 001- 10 lected in a receiver 21. From the receiver 21, the'liquid refrigerant is forwarded through a supply conduit 28 under the control of a suitable control device such as a restrictor 29 which is provided with a nozzle 30 located within a 15 Venturi tube 3|.

The restrictor 29 and the nozzle 30 change the pressure energy of the liquid refrigerant into velocity energy and discharge a stream of liquid into the venturi at a high velocity. This 20 forms a jet pump which pumps vapor from the suction chamber 32 of this jet Venturi means. The nozzle 30 may be moved parallel to the axis of the Venturi tube in order to vary the pumping effect of this jet. The liquid refrigerant dis- 5 charged from the nozzle 30 of the jet pump flows into the high temperature evaporator 24.

When thehigh temperature evaporator 24 is filled with liquid refrigerant, the float valve 33 within the float chamber 34 is lifted to open the 30 valve and permit the surplus liquid refrigerant to flow through the tubing 35 into the lower por-' tion of the freezing evaporator 22. The liquid refrigerant within the freezing evaporator 22 evaporates and absorbs the heat from any water 5 in the ice trays 36 and the ambient air within the freezing compartment and this evaporated refrigerant is removed through the tubing 31 connected to the suction chamber 32 of the jet Y pump which creates a substantially lower evapo- 40 rating pressure in the freezing evaporator 22 thanin the high temperature evaporator 24.

The liquid refrigerant within the high temperature evaporator 24 evaporates and absorbs heat from the ambient air withinthe food conipartment 23 and this evaporated refrigerant is withdrawn from the top of the float chamber 34 through the return conduit 40 which is connected to the inlet of the compressor 25. The compressor 25 is driven by an electric motor 4| which is connected in series with the snap acting switches 42 and- 43 which are connected in parallel electric circuit relation with each other and which are controlled respectively by the thermostatic bulb 44 located within the freezing compartment M and the thermostatic bulb 45 located within the food storage compartment 23. Thus, when refrigeration is required in either of these compartments, the compressor is caused to operate so as to supply refrigeration thereto. However, if desired, the switches 42 and 43 may be placed in series so that the refrigerating system will operate only when both of the compartments require refrigeration. i

By employing the jet pump means operated by the pressure difference between the pressure of the liquid refrigerant in the receiver or high side of the refrigerating system and the pressure within the high temperature evaporator 24, a substantially lower evaporating pressure and temperature is created within the freezing evaporator 22 than in the high temperature evaporator 24 without the use of additional energy. In addition to this gain in efliciency by the use of the two evaporators, one for freezing purposes and one for cooling the food storage compartment, the high temperature evaporator 24 may operate at a much higher evaporating pressure and temperature than when only one evaporator operating within a single pressure range is employed for both the freezing of ice cubes and comestibles, as well as for cooling the food storage compartment. This enables the compressor 25 to operate at a higher back pressure than customary with household refrigerating systems employing but a single evaporator and this, of course, reduces the load upon the compressor 25 of the electric motor 4|, because the pressure difference between the refrigerant pressure on the inlet side of the compressor and that on the outlet side of the compressor is considerably less.

This system also permits the freezing evaporator to be operated at lower temperatures than is customary where a single evaporator is employed for both freezing and box cooling purposes. As a result of this, freezing can be done much more quickly in a refrigerator of this type than in those now commonly used. By operating the food storage compartment evaporator at a high temperature, which, of course, is below the desired food compartment temperature, a relatively high humidity may be maintained within the food storage compartment 23 and dehydration of foods and particularly dehydration of vegetables may be avoided.

In Fig. 2, there is shown a two temperature household refrigerator 50 having an insulated freezing compartment 5| containing a freezing evaporator 52 and an insulated food storage compartment 53 separate from and insulated from the freezing compartment 5! and provided with a high temperature evaporator 54. Liquid refrigerant is supplied to the evaporators by a refrigerant liquefying apparatus including a compressor 55 for compressing the refrigerant and for forwarding the compressed refrigerant to a condenser 56 where the compressed refrigerant is liquefied and collected in a receiver 51. From the receiver 51, the liquid refrigerant is forwarded through a supply conduit 58 under the control of a suitable control device, such as a restrictor 59, which controls the flow of liquid gifrigerant into the high temperature evaporator As in the form shown in Fig. 1, the outlet of the high temperature evaporator 54 is provided with a float valve 50 within the float chamber H which permits the surplus of liquid refrigerant from the high temperature evaporator to fiow through the conduit 52 into the freezing evaporator 52. The liquid refrigerant within the high temperature evaporator 54 evaporates and absorbs heat from the air within the food storage compartment 53 and this evaporated refrigerant is conducted from the top of the float chamber 6| by the return conduit 53 to the crank case 54 of the compressor 55. The liquid refrigerant within the freezing evaporator 52 evaporates and absorbs heat from the ice trays 65 and this evaporated refrigerant is conducted through a second return conduit 65 to the inlet chamber 81 of the compressor 55.

The compressor 55 disclosed in Fig. 2 is of a suitable or conventional construction to provide a so-called multiple effect compressor. In other words, when compressor 55 is operated it withdraws a certain amount of gaseous refrigerant from each of the evaporators of the system and forces the combined withdrawn charge of gaseous refrigerant under pressure into the condenser 55. Operation of the multiple effect compressor 55, therefore, causes refrigerant evaporated in evaporator 52 to be drawn through conduit 66, inlet chamber 61, and under control of a suitable inlet valve 68 into the compression chamber 69 provided between the cylinder head and the compressor piston 10. This withdrawing of evaporated refrigerant from evaporator 52 occurs during the down stroke of piston 10 and when the piston reaches its lowermost position of its down stroke a passage H, connecting the compressor crankcase 64 with the compression chamber 59, is uncovered. Evaporator 54 communicates, by way of conduit 63, with the interior of compressor crankcase 64, and since the refrigerant evaporated in evaporator 54 is of higher pressure than refrigerant evaporated in evaporator 52 this high pressure refrigerant vapor flows, when piston Ill uncovers passage 1 I, from the compressor crankcase 64, through passage ii, into the compression chamber 69. Upon each down stroke of piston 10, the chamber 59 is thus filled with gaseous refrigerant comprising a mixture of refrigerant evaporated from each evaporator 52 and 54 and which mixture is of a pressure corresponding to the evaporating pressure of the high temperature evaporator 54. By substantially simultaneously withdrawing evaporated refrigerant from each ,evaporator 52 and 54 a high volumetric efficiency is insured for the multiple effect compressor 55. Thecombined charge or mixture of gaseous refrigerant so drawn into the compression chamber 69 is compressed by the up stroke of piston 10 of compressor 55 and flows through a suitable pressure actuated outlet valve 12 into condenser 56 where it is cooled and liquefied.

A similar electrical systemis provided for this refrigerating system including the compressor motor 13 for driving the multiple effect compres-,

creating the pressure differences between the freezing evaporator and the high temperature evaporator.

In Fig. 3 there is an air conditioning system embodying my invention including a high temperature evaporating means 80 adapted to contain liquid refrigerant and a low temperature evaporating means 8| also adapted to contain liquid refrigerant. These evaporators 99 and 8| are located within an air conditioningunit 82 which is provided with a centrifugal fan 83 driven by an electric motor 84 which circulates or discharges the fluid medium to be cooled, namely: air, upwardly, first over the surfaces of the high temperature evaporator 89 and then over the surfaces of the low temperature evaporator 8| after which the air is discharged through the screen or grille work 85 in the top of the air conditioning unit 82 which distributes the cooled air into the room.

The evaporating means is supplied with liqui refrigerant by a refrigerant liquefying apparatus 89 which is preferably located outside of the room or space to be cooled or which has its heat removed from the room in some suitable manner. This refrigerant liquefying. apparatus 86 includes a compressor 81 for compressing the refrigerant and for forwarding the compressed refrigerant to a condenser 88 where the compressed refrigerant liquefies under the influenceof pressure and cooling. This liquid refrigerant is cooled ina receiver 89 and forwarded through a supply conduit 99 under the control of a thermostatic valve 9I to a restrictor or other suitable control means 92 which, together with the nozzle 93 changes the pressure energy of the liquid refrigerant into velocity energy within the venturi 94 of a jet pump which has an inlet or suction chamber 95. The liquid refrigerant discharged from the nozzle 93 flows into the high temperature evaporator 89 and cools the air flowing over its surfaces a certain amount which is insufficient to properly cool the air in the room. This evaporated refrigerant is returned to the compressor through thereturn conduit 96.

Liquid refrigerant is supplied from the lower portion of the high temperature evaporator 99 through a conduit 91 under the control of a thermostatic valve 98 to the low temperature evaporator 8| where the evaporation of the liquid refrigerant further cools the air which is circulated through the air conditioning unit, so that the air will finally be discharged at the desired discharge temperature. The refrigerant which evaporates in the ,low temperature evaporator 8| is withdrawn through the conduit 99 which is connected to the suction chamber 95 of the jet pump for this purpose. The thermostatic valve 9I is controlled by a thermostatic bulb I99 in heat exchange relation with the return line 98 so as to stop the supply of liquid refrigerant when liquid refrigerant enters the return conduit 98. Likewise, the thermostatic bulb IN is placed in heat exchange relation with the conduit 99 so as to closethe thermostatic valve 98 when any liquidrefri gerant reaches that portion of the conduit 99.

The compressor 8'I is driven by an electric motor I92 under the control of a'snap acting switch I93 controlled by a thermostatic bulb I94 located within the air in the room or space to be cooled. By the use of this system,'the air may be cooled more eficiently by employing the jet pump which is operated by the pressure energy of the liquid refrigerant from the high pressure side of the system to create a lower evaporating pressure and temperature within the evaporator which finally cools the air to the desired temperature. "In this way, the desired temperature difierences between the air flowing over the evaporating surfaces and the temperature of the evaporated surfaces may be maintained so as to effect rapid heat transfer therebetween. By employing a plurality of evaporators and by employing the jet pump to create a lower evaporating pressure and temperature in the final or low temperature evaporator, the system-may operate at a higher back pressure than when only a single evaporating means operating at a single evaporating pressure range is employed. This enables the air conditioning to-be. done more efliciently and more economically.

In Fig. 4 there is shown an air conditioning unit I29 containing a high temperature evaporator I2I and a low temperature evaporator I22. An electrically driven fan I23 controlled by the switch I24 is provided for circulating thefluid medium to be cooled, namely: air, first over the surfaces of the high temperature evaporator I2I and then 'over the surfaces of the low temperature evapothe compressed refrigerant to-the condenser I28 where the. compressed refrigerant is liquefied and cooled in a receiver I29. From the receiver I29, the liquid refrigerant is forwarded through a supply conduit I39 under the control of a suitable expansion control device such as a restrictor I3I' which controls the supply of liquid refrigerant to the high temperature evaporator I 2 I.

The outlet of the high temperature evaporator I 2I is provided-with a float chamber I32, containing a float control valve I33 which permits the evaporatedrefrigerant to return through the return conduit I34 to the crank case I35 of the compressor I21 while any surplusliquid refrigerant is permitted to flow through the conduit I36 to the low temperature evaporator I22. The refrigerant evaporates within the low temperature evaporator I22 and cools the air to the desired discharge temperature after the air has been pre-cooled by the high temperature evaporator I2I. The evaporated refrigerant from the low temperature evaporator is returned to the inlet chamber I38 of the compressor I21 through a return conduit I39.

The compressor I21 in Fig. 4 is similar to the compressor disclosed in the system shown in Fig. 2 in that it is of a construction to produce a multiple effect. The multiple effect compressor I21 includes a piston I49 which has a port I43, covered by a valve I48, extending therethrough.

During operation of the compressor I21 and when the piston I49 thereof moves downwardly refrigerant evaporated in the low temperature evaporator I 22 is caused to flow through conduit I39, chamber I38 and past a valve I42 into the compression chamber MI. The compressor piston I49 upon reaching the bottom of its down stroke moves the port I33 provided therein below the cylinder wall and into communication with the crankcase I35. Refrigerant evaporated in the high pressure evaporator I2I then flows through conduit I34, crankcase I35, port I43 and past the valve I48 into the compression chamber I4I. Thus the charge of gaseous refrigerant entering the compression chamber I4I upon each down i is cooled in any well-known or conventional manner and liquefied. It is to be understood that, while I have disclosed multiple effect compressors for the systems shown in Figs. 2 and 4 of certain construction, other compressor structures capable of producing a multiple effect may be employed without departing from the spirit of the invention.

The compressor I21 is driven by an electric motor H5 which is controlled by a snap acting switch operated by a thermostat 1 located within the air in the room or space to be cooled. In this system, I have employed a similar liquid control for supplying liquid refrigerant to the low temperature evaporator and have employed a high temperature and a low temperature evaporator in order to secure a high average back pressure and the systems disclosed are well-known to those skilled in the art and it is to be understood that I may employ other conventional restrictors such as valves, etc., without departing from the invention. Since the various systems disclosed are only diagrammatically shown it is also'to be understood that the jet Venturi means employed therein may be positioned wherever desired or practicable to carry out the functions of the systems as described. For example, the jet Venturi means may be located on or above the normal liquid refrigerant level maintained in the evaporator into which the Venturi means discharges liquid refrigerant.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus including a condenser and a plurality of evaporators, a compressor for pumping refrigerant from the evaporators to the condenser and creating a higher pressure in the condenser than in the evaporators, said refrigerant being liquefied in the condenser, means for conducting and controlling the flow of liquid refrigerant from the condenser to one of the said evaporators, means for supplying liquid refrigerant from said one evaporato1 to another of said plurality of evaporators, said conducting and controlling means including pumping means energized by the pressure energy of the liquid refrigerant for creating a substantially lower evaporating pressure in one of the evaporators than in another, and means for circulating a fluid medium first over one of the evaporators having a higher evaporating pres sure and then over one evaporator having a lower evaporating pressure.

2. The process of refrigeration which comprises withdrawing evaporated refrigerant from an evaporating space, compressing the evaporated refrigerant and cooling the compressed evaporated refrigerant to liquefy the refrigerant, converting the pressure energy of the liquefied refrigerant into velocity energy, utilizing the velocity energy of the liquefied refrigerant to withdraw evaporated refrigerant from a second evaporating space to create a lower pressure in the second evaporator space than in the first mentioned evaporator space, discharging the liquefied refrigerant into the first mentioned evaporating space, conducting liquid refrigerant from said first mentioned evaporating space into the second evaporating space, and passing a fluid medium to be cooled into heat exchange relationfirst with the first mentioned evaporating space and then into heat exchange relation with the second evaporating space.

3. Refrigerating apparatus including a low temperature and a high temperature evaporator, a condenser and a compressor for pumping evaporated refrigerant from one of said evaporators into the condenser and creating a higher pressure within the condenser, said refrigerant being liquefied in the condenser, means for conducting and controlling the flow of liquid refrigerant to said evaporators, said means including separate means for restricting the flow of liquid to the low temperature evaporator, said conducting and controlling means including pumping means energized by the pressure energy of the liquid refrigerant for creating with the aid of the separate restricting means a lower evaporating pressure within the low temperature evaporator than in the high temperature evaporator, and means for directing the circulation of a fluid medium to be cooled first in heat exchange relation with the high temperature evaporator and thereafter in heat exchange relation with the low temperature evaporator.

4. Refrigerating apparatus including a plurality of evaporators, means for supplying liquid refrigerant to and for withdrawing gaseous refrigerant from said evaporators, means for conducting liquid refrigerant pre-cooled in one of said evaporators therefrom and controlling its entrance into another of said evaporators, means utilizing the energy of refrigerant flowing from said supply means to said one of said evaporators for creating a substantially lower evaporating pressure within said another evaporator than in said one evaporator, and means for directing the circulation of a fluid medium to be cooled first into heat exchange relation with said one evap-' orator and thereafter into heat exchange relation with said another evaporator.

DON E. DASHER.

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