US3381491A - Refrigeration systems having liquid cooled condensers - Google Patents

Description

United States Patent 3,381,491 REFRIGERATION SYSTEMS HAVING LIQUID COOLED CONDENSERS James R. Hamish, Staunton, Va., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 23, 1966, Ser. No. 552,057 6 Claims. (Cl. 62-218) ABSTRACT OF THE DISCLOSURE A refrigeration system having a compressor with loading-unloading means, has a shell-and-tube type condenser, with water flowed through the tube, and the refrigerant liquid collecting in the bottom of the shell. The expansion valve of the system responds to the level of the refrigerant liquid within the shell; adjusts towards closed position on a decrease in such level, and adjusts towards open position on an increase. in such level.

This invention relates to refrigeration systems having liquid-cooled condensers, and has as an object to adjust an expansion valve in accordance with changes in the level of refrigerant liquid Within such a condenser.

My copending application, Ser. No. 447,008, filed Apr. 9, 1965, issued as Patent No. 3,264,837, discloses the advantages of using an expansion valve which supplies re frigerant to an associated evaporator at the rate at which the refrigerant is condensed within an associated condenser, thus keeping the condenser adequately drained, and overfeeding the evaporator so that all of its internal surface is thoroughly wetted. The unevaporated refrigerant fiowing from the evaporator is prevented from flowing into the associated compressor, by flowing it into an accumulator where it is evaporated by heat from the high pressure liquid, the latter being subcooled by this action. That expansion valve is a subcooling control valve which maintains a predetermined amount of subcooling of the condensed refrigerant, backing it up in the condenser until the desired amount of subcooling is obtained. In such a system, when a liquid-cooled, shell-and-tube type condenser is used, with the condenser cooling liquid flowing through the tubes, and with the condensed liquid in contact with the exterior surfaces of the tubes, a subcooling control valve is not satisfactory when the compressor is unloaded to, for example, its 25% capacity point because of the lack of sufficient refrigerant liquid to provide the subcooling.

This invention substitutes for the subcooling control valve of the system of said application, an expansion valve which is adjusted by a float-operated pilot valve which responds to the level of liquid refrigerant within such a condenser. When the liquid level increases, the pilot valve adjusts the expansion valve to supply more refrigerant to the evaporator, and vice versa. Thus, the expansion valve supplies refrigerant to the evaporator at the rate at which the refrigerant is condensed.

This invention will now be described with reference to the annexed drawing which is a diagrammatic view of a refrigeration system embodying this invention, with the condenser of the system shown in section.

Referring now to the drawing, a conventional refrigerant compressor C, driven by an electric motor CM, has cylinders GL1, GL2, GL3 and GL4, with cylinder heads H1, H2, H3 and H4 respectively. The discharge side of the compressor C is connected by discharge gas tube containing a high pressure cut-out HPC to the refrigerant inlet of a shell-and-tube type condenser 12. The refrigerant outlet of the condenser 12 is connected by liquid tube 13 to the refrigerant inlet of heat exchange coil 14 within accumulator 15. The refrigerant outlet of the coil 3,381,491 Patented May 7, 1968 "ice 14 is connected by tube 16 containing an expansion valve EV, to the refrigerant inlet of evaporator 17 which may be an air cooling evaporator coil. The refrigerant outlet of the evaporator 17 is connected by tube 18 to the top of the accumulator 15 at one end of the latter. The top of the accumulator 15 at its opposite end is connected by suction gas tube 20 containing a suction pressure control SPC to the suction side of the compressor C.

The condenser 12 contains the usual tubes 22 through which a liquid such as water is circulated to cool and condense the refrigerant gas entering the condenser. A conventional float-operated, pilot valve 23 is connected by tube 24 to the upper portion of the condenser 12, and is connected by tube 25 to the bottom of the condenser 12. The expansion valve EV has a diaphragm chamber 26 connected by a small tube 27 to the pilot valve 23. The pilot valve 23 may be a conventional Phillips pilot valve No. 270, and the expansion valve EV may be a conventional Phillips expansion valve No. 801. The construction of such valves is disclosed in my patent No. 3,350,898. Refrigerant liquid having a level 30 collects within the lower portion of the interior of the condenser 12. The valve 23 responds to changes in the level 30, and adjusts the valve EV to supply more refrigerant to the evaporator 17 on an increase in the level 30, and adjusts the valve EV to supply less refrigerant to the evaporator 17 on a decrease in the level 30. Thus, the valve EV supplies refrigerant to the evaporator 17 at the rate at which the refrigerant is condensed within the condenser 12.

The cylinder head H2 has the plunger of a solenoid S1 extending therethrough to depress, when the solenoid S1 is deenergized, the usual suction valve reeds, which are not shown, to unload the cylinder GL2. The cylinder head H3 has the plunger of a solenoid S2 extending therethrough to depress, when the solenoid S2 is deenergized, the usual suction valve reeds which are not shown, to unload the cylinder GL3. The cylinder head H4 has the plunger of a solenoid S3 extending therethrough to depress, when the solenoid S3 is deenergized, the usual suction valve reeds which are not shown, to unload the cylinder GL4. Corresponding ends of the solenoids S1, S2 and S3 are connected by wire 36 to electric supply line L2. The other end of the solenoid S1 is connected by wire 37 to switch contact 38. The other end of the solenoid S2 is connected by wire 39 to switch contact 40. The other end of the solenoid S3 is connected by wire 41 to switch contact 42. The suction pressure control SPC has a plunger 45 pivoted to switch arm 46 between the ends of the latter. The switch arm 46 is pivoted at one end to fixed support 47, and its other end is shaped to contact the switch contacts 38, 4t} and 42. The switch arm 46 is connected by wire 49 to electric supply line L1.

The compressor motor GM is connected by wire 50 to line L2, and by wire 51 to switch 52 of compressor motor starter MS, which switch is connected to the line L1. The starter MS has an energizing winding 54 connected in series with switch 55 of the cut-out HPG, and switch 56 of thermostat T to the lines L1 and L2.

The system is overcharged with refrigerant so that there is normally a quantity of refrigerant liquid within the accumulator 15.

Operation When the thermostat T which may be an indoor or outdoor thermostat, calls for cooling, it closes its switch 56 which energizes through the normally closed switch 55 of the cut-out HPC, the winding 54 of the motor starter MS which closes its switch 52, energizing the motor CM, and starting the compressor G. Discharge gas from the compressor C flows through the tube It) and the cut-out HPG into the condenser 12 where it is: cooled and condensed by the water circulated through the condenser tubes 22. Refrigerant liquid flows from the condenser 12 through the tube 13, the coil 14 within the accumulator 15, the tube 16 and the expansion valve EV into the evaporator 17. Gas and unevaporated refrigerant liquid flow from the evaporator 17 through the tube 18 into the accumulator 15. Gas separated from the liquid within the accumulator 15 flows through the suction gas tube 20 and the suction pressure control SPC to the suction side of the compressor C.

Heat from the high pressure liquid flowing through the coil 14 within the accumulator 15, evaporates the unevaporated refrigerant liquid flowing from the evaporator 17 into the accumulator, the high pressure liquid being subcooled by this action.

At the maximum load on the evaporator coil 17, the compressor C operates with all four cylinders GL1, GL2, GL3 and GL4 loaded. At such time, the suction pressure is such that the switch arm 46 of the suction pressure control SPG is in contact with all of the switch contacts 38, 4t) and 42, energizing all of the solenoids S1, S2 and S3. As the load on the evaporator coil 17 decreases, the suction pressure decreases, and the switch arm 46 moves out of contact with the switch contact 42, deenergizing the solenoid S3 which unloads the cylinder GL4. On a further decrease in the load, the suction pressure decreases further, and the switch arm 46 moves out of contact with the switch contact 40, deenergizing the solenoid S2 which unloads the cylinder GL3. On a further decrease in the load, the suction pressure decreases further, and the switch arm 46 moves out of contact with the switch contact 38, deenergizing the solenoid S1 which unloads the cylinder GL2. At this time, the compressor is unloaded down to its 25% capacity point with the cylinder GL1 only, loaded. The volume of discharge gas is so reduced, and the resulting quantity of refrigerant liquid condensed within the condenser 12 is so reduced that a subcooling control valve such as is disclosed in my said application cannot operate properly. The float operated, pilot valve 23 responds, however, to the reduced level of the refrigerant liquid within the condenser 12, and adjusts the expansion valve EV to supply to the evaporator coil 17 a conformably reduced quantity of refrigerant liquid.

While this invention has been described as embodied in a non-reversible refrigeration system, it could, of course, be embodied in a heat pump.

What is claimed is:

1. A refrigeration system comprising a refrigerant compressor; a condenser; an expansion valve; and an evaporator; connected in series in the order named in a refrigeration circuit, said condenser being a shell-and-tube type condenser with internal tubes through which a cooling fluid is flowed for cooling said condenser; means including means responsive to changes in the level of refrigerant liquid within said condenser for adjusting said expansion valve towards open position on an increase in said level, and towards closed position on a decrease in said level, and means using refrigerant liquid flowing from said condenser to heat and evaporate refrigerant liquid flowing from said evaporator.

2. A refrigeration system as claimed in claim 1 in which said means responsive to changes in said level comprises a float-operated, pilot valve connected to said expansion valve.

3. A refrigeration system as claimed in claim 2 in which means is provided for varying the output of said compressor.

4. A refrigeration system as claimed in claim 3 in which said output varying means comprises compressor loading and unloading means.

5. A refrigeration system as claimed in claim 1 in which means is provided for varying the output of said compressor.

6. A refrigeration system as claimed in claim 5 in which said output varying means comprises compressor loading and unloading means.

References Cited UNITED STATES PATENTS 1,106,287 8/1914 Doelling 62-222 XR 1,994,037 3/1935 Gay 62218 2,161,960 6/1939 Hintze 62-218 2,295,992 9/1942 Gonzalez 62-4218 XR MEYER PERLIN, Primary Examiner.

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