US2050002A - Refrigeration system - Google Patents

Description

Aug. 4, 1936.

J. W. GILBERT REFRIGERATION SYSTEM 2 Sheets-Sheet 2 Filed Oct. 6, 1954 WQN o 1% N. W \\\\A EN kkmfikwm .v MN. WMN \SQQ A v UN @1134 I k Illll fiw z Patented Aug. 4, 1936 PATENT OFFICE REFRIGERATION SYSTEM James W. Gilbert, .Johnstown, Pa., assignor of one-half to Ernest F. Walker, Johnstown, Pa.

Application October 6, 1934, Serial No. 747,172

7 Claims.

This invention relates to improvements in the art of mechanical refrigeration, primarily designed for refrigeration systems in which a cooling medium or refrigerant is circulated from a 5 common source through a multiple series of cooling coils or units in a single installation.

In the improved types, such cooling systems generally include a compressor delivering compressed refrigerant to a condenser and a liquid 10 receiver, from whence a supply conduit or line delivers the liquid refrigerant through connecting branch lines to each of the separated independent cooling coils or units. Return lines from said units communicate with the compressor 15 through a common return conduit to provide a closed system.

Each of the several cooling units or refrigerators has usually associated therewith an expansion or float valve and an automatic regulat- 20 ing or two-temperature control valve combining a to provide the desired individual temperatures in the several units.

In the operation of these multiple coil or freezing unit installations, both in the domestic and 25 the commercial fields, considerable difliculty has been experienced in maintaining stable temperatures in the various units. While the system may operate satisfactorily so long as the compressor is operating, when the compressor is in- 30 active boiling frequently occurs in the suction or return lines, flooding the same with wet gas, and causing frozen lines and a frozen compressor. The compressor running time becomes excessive, tubing collapses, flare units break, and 35 the system is ineffective until repaired. Likewise, the pressure of wet gas in the return line producesfoaming of the oil in the compressor, causing damage to valves and other working parts of the system.

40 I have discovered that these highly objectionable reactions and costly interruptions of service result from back-pressure set up upon the warming up of the coil and line which absorbs the greatest amount of heat, which back-pressures 45 are transmitted to the coils and lines of one or more units operating at relatively lower pressures. This higher pressure refrigerant is promptly absorbed and condensed in the low pressure coil or coils, thereby raising the liquid 50 levels therein and prematurely raising the pressures and temperatures above normal. When the compressor starts, the excessive amounts of refrigerant contained in said coils gushes down the suction lines flooding the same with wet gas and causing freezing, etc. as stated above.

When this action takes place, all means heretofore employed for temperature or pressure control become ineffective until the entire system is again pumped down and each individual unit acquires its predetermined pressure and the resulting temperature.

It is a prime object of my invention to provide, particularly in a multiple refrigeration system, individual automatically operable control means for preventing the back flow or reverse circulation of refrigerant between the coils and lines of two or more separate units of the system operating at different pressures and temperatures, operable in connection with the ever present entrained oil circulating with the refrigerant to form an eflicient barrier to said circulation.

I further contemplate a simple and efilcient control means readily adaptable to present installations, and a control means applied in close proximity to the evaporator or cooling, coil and on the return side thereof, to utilize the semisolid or congealed oil discharged therefrom as a sealing medium. v

My invention may be more clearly understood from the following description taken in connection with the accompanying drawings, wherein:

Fig. 1 is a diagrammatic view of a multiple refrigeration installation, showing the application of my invention thereto;

Fig. 2, an enlarged longitudinal vertical sectional view of one of the evaporators and the control means of the present invention; and

Fig. 3, a detail section taken on the line III III of- Fig. 2.

For the purpose of illustration, I have shown herein a multiple installation including a plurality of cooling units or refrigerators desired to be operated at different temperatures, but it will 'be understood that my invention is not to be limited thereto, as the same may be embodied in any mechanical refrigeration system whether it be a multiple installation or a single unit.

Referring to the drawings, 5 designates a compressor of the reciprocating type driven by a 40 motor 6 to compress and discharge a cooling medium or refrigerant, as for example, sulphur dioxide, into a condenser l and thence into a liquid receiver or tank 8.

The refrigerant in liquid form is passed from the receiver 8 through a pipe or line 9 to the cooling units mounted in compartments or refrigerator cabinets A, B, C and D through branch lines 9a, 9b, 9c, and 9d respectively. For the purpose of simplicity, the various elements in the individual compartment systems are given reference numerals having letters corresponding to the compartment designation above, and but one of said compartment systems is described in detail, the others having like elements, as will be readily seen and understood. Thus, in compartment A, the branch line So communicates with an evaporator or boiler Illa through a shut-off valve I la and a float valve control comprising a needle valve l2a operable absorption surface of the unit. The gaseous refrigerant in the evaporator,

produced by the low pressure expansion of the refrigerant, upon the absorption of heat passes outwardly from the said evaporator through a return or suction line its having a shut-off valve l6a. The lines lBa, lib, I50, and lid communicate with a common return line I! connecting with the suction side of the compressor 5. Ha, Ilb, lie, and lid designate control valves in the return or suction lines of the respective compartments, said valves being of standard construction and operating by reason of either pressure or temperature variations to control the flow of refrigerant in said lines to the compressor I. These valves are generally designated in the art as an automatic regulating valve or a twotemperature snap-action valve.

Electrically connected in circuit with the m0- tor 6 is an automatic pressure control switch l8 having connection .with the suction and discharge sides of the compressor 5 by pipes l9 and 20 respectively, said pipes having bellows operable by pressure variations to open and close the motor circuit at predetermined pressures or i temperatures in; the system. 2| refers to the circuit connections with a suitable source of electricity or power line 22 through a main switch 23.

Assuming the float and automatic regulating valves to be adjusted to provide different pressures in the several units or compartments, as is the case in certain commercial installations, the system is charged with refrigerant and the control switch I 8 adjusted to regulate the cutin and cut-out of the compressor at predetermined pressures, said adjustment generally being in accordance with the temperature variation permitted in the compartment desired to be maintained at the lowest temperature of the entire installation.

temperatures of the refrigerant in the other units, and when the compressor is cut-in by the control switch la, the same must necessarily operate for an extended period of time in order to again pump down all of said units.

In addition, this back or inter-flow between units raises their temperatures and pressures to such a degree that boiling occurs in the evaporators and suction lines, flooding said lines with wet gaseous refrigerant and eventuating in frozen lines and freezing of the refrigerant in the compressor.

Likewise, in such refrigeration apparatus, the suction lines I 5, I511, lib, lie, and lid are generally of considerable length, either individually or collectively, depending upon the location of the compressor. relatively to the cooling units. Frequently in large installations, the compressor is placed in a basement or far removed room, necessitating long suction lines within the buildi s. V

In such installations, it not infrequently happens that the said suction lines pass through tion line to the evaporator.

substantially warm regions which have a similar effect to that just described, causing a backpressure flow of refrigerant to the evaporators and interrupting the regularity of the cycle and the desired temperatures.

As is general practice, oil is present in the system, being originally introduced to the lower crank case of the compressor 5, which oil is entrained at compression and passes through the system with and suspended in the refrigerant in the form of globules or particles, said oil supplying lubrication for the parts of the entire system. During the above-mentioned boiling, this oil foams and its lubrication value is destroyed, resulting in injury to the moving parts of the system.

To obviate these difliciilties and to provide for stable conditions in the system and the several individual units, I have provided automatically operable means in the form of a control valve, 20

tions, but I prefer to provide the same of the 25 type having a hollow body 24 enclosing a reciprocable stem valve 25 on a seat 26 at the end of said body next to the evaporator or boiler I001. 21 designates a spring normally seating said valve against any return flow from the suc- 30 Standard flare connections." connect the valve in the suction line 15a.

With the valve E so positioned, it is readily seen that any back or interflow between units 3 is prevented, the said valves acting as automatic checks to permit flow of refrigerant in one direction only, i. e., to the compressor from the evaporator. Hence, in operation, the various temperatures or pressures in the several units or compartments are maintained within their respective predetermined ranges without appreciable variation.

It is well known in the art that considerable difficulty is encountered in the sealing of connections or the seating of valves, due to the great tendency of the standard refrigerants to penetrate and leak.- Failure of the valves E to seat perfectly will render the same inefllcient.

In order to insure proper seating or closing of the valves E, I prefer to position said valves in the suction lines-of the respective units adjacent to or as close as possible to the evaporator-s. The oil particles entrained by the, refrigerant form slugs or globules, which lie along the upper surfacev of the liquid refrigerant in the evaporators, as indicated in Fig. 2, in a semi-solid or congealed state, due'to the lowtemperatures.

Said slugsare" carried by the expanded refrigerant from the evaporators immediately to the control valves E, where they form sealing films around the valves 25- and their seats 26, thus providing refrigerant-tight seals, preventing any leakage.

In addition, the major portion of the oil passes directly through the valves E to the com-' pressor for re-circulation. There is no trapping of the oil when-the valves are located next to the evaporator because of said congealed condition, the particles thereof being readily carried in suspension by the moving refrigerant. The oil in a less viscous state, as would be the case at a point further along in the lower and warmer regions of the suction lines, would not provide an eflicient seal and, likewise, should the valves'E be placed at such lower regions, the oil in a liquid state would be trapped in the lowermost points of the valves.

Also, by positioning the valves E next to the evaporator, and acting as they do to prevent back-flow to said evaporators from the suction lines, any increase of pressures in the suction lines due to heating up as before, will have no effect upon the evaporators, since the valves completely prevent any return communication with said evaporators.

A mechanical refrigeration system equipped with my invention will be entirely stable and uniform in its operations. In a multiple instal lation such as that shown and described, various temperatures are maintained as desired in the separate cabinets or compartments/by adjusting the expansion valves at the evaporators, and setting the automatic or two-temperature control valves in the suction lines.

The compressor control through its switch I8 is also aided by the provision of the valves E due to the fact that only the change in pressure within any individual evaporator acts upon said switch, without the influence of irregular variations of back-pressure as has heretofore been experienced. Hence, the compressor operates only when needed to re-service one or more units which have become warm through use, and the actual running time of the compressor is thereby materially decreased over present practice.

This accurate control of ,pressures and temperature is also accomplished by the use of my invention in apartment house installations where a plurality of units are operated at the same temperature, and will effectively protect such system against variations caused by unequal application of the load upon the individual units. It may be said that each unit provided with a valve E in the manner described will have complete individual control of the switch l8, thereby operating as emciently as a single unit system.

My invention may be applied in a like manner to a single unit system with equal advantage. It is well known that the suction and discharge valves of the compressor eventually leak, thereby causing back-pressures in the return or suction line, which, when transmitted to the evaporator, cause the compressor to run longer and more frequently than is necessary. By incorporating my invention in the manner set forth herein, any back-flow or pressure due to leaking valves will have no effect upon the cooling cycle of the unit, since the same cannot enter the evaporator.

I claim:

1. In a refrigeration system comprising a closed system including a compressor, a condenser and a single evaporator, a liquid fluid line from the condenser to the evaporator, a suction line connecting said evaporator and the compressor, and automatically operable means disposed in the suction line associated with the evaporator preventing a back flow of refrigerant created between the compressor and the evaporator to the evaporator.

2. In a refrigeration system comprising a closed system including a compressor, a condenser and a single evaporator, a liquid fluid line from the condenser to the evaporator, a suction line connecting said evaporator and the compressor, and an automatically operable valve disposed in the suction line, a part of said suction linerigidly connecting the body of said valve to the casing of said evaporator preventing a back flow of refrigerant created between the compressor and the evaporator to the evaporator. 5

3. In a refrigerationsystem comprising a closed system including a compressor, a condenser and an evaporator in which a suitable refrigerant mixed with lubricating oil is employed, a suction line connecting said evaporator and the compressor, and an automatically operable spring-seated valve disposed in the suction line associated with said evaporator preventing a back flow of refrigerant to the evaporator, said valve receiving the oil as it passes from the evaporator in a congealed state to effect a seal between said valve and its seat.

4. In a refrigeration system comprising a closed system including a compressor, a condenser and a plurality of evaporators, a fluid ing valves adjacent the suction line, and independent automatically operable means associated with each evaporator and disposed in the suction line associated with each evaporator for preventing a return flow of refrigerant to any 1airlid all of the evaporators from said suction 5. In a multiple refrigeration system compris= ing a plurality of cooling units having individual evaporators connected with a compressor and condenser for the circulation of a refrigerant, suction lines from each of said evaporators connecting with the suction side of said compressor, automatically operable valves disposed in said suction lines adjacent each evaporator for preventing a back and interflow of refrigerant to and between any and all of the said evaporators by reason of back pressures in the suction lines, and as and for the purpose described.

6. In a multiple refrigeration system compris= ing a plurality of cooling units havingindividual evaporators connected with a compressor and condenser for the circulation of a refrigerant, individual suction lines from each of said evaporators leading to a common suction line, the latter connecting with the suction side of said compressor, regulating valves in the common suction line, and automatically operable valves disposed in the individual suction lines associated with the evaporators for preventing a back and interflow of refrigerant to and between any and all of the said evaporators.

7. A multiple refrigeration system comprising a plurality of cooling units each. having an evaporator. a compressor and condenser with so which each evaporator is operatively' connected for circulating refrigerant, suction lines from each of said evaporators connected to the suction side of said compressor, automatically operable valves disposed one in each suction line, 65 a part of each suction line rigidly connecting the valve thereof to the associated evaporator to prevent a back and interflow of refrigerant to and between said evaporators.

I JAMES w. GILBERT.

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