Methods of freezeout prevention and temperature control for very low temperature mixed refrigerant systems
First Claim
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1. A very low temperature refrigeration system utilizing mixed refrigerants, the system comprising:
- a compressor in fluid communication with a refrigeration process, the refrigeration process including a high pressure line on a high pressure side of the refrigeration system between the compressor and an evaporator, a low pressure line on a low pressure side of the refrigeration system in a refrigerant return path between the evaporator and the compressor, and at least one heat exchanger cooling refrigerant in the high pressure line from refrigerant in the low pressure line; and
a bypass circuit connected either;
a) from a point in the refrigeration process where high pressure refrigerant flows, prior to where the high pressure line exits a cold end of the refrigeration process, and to a point in the refrigeration process where the coldest low pressure refrigerant in the system flows, the bypass circuit including a valve controlling bypass flow of bypassed refrigerant, the result of the bypass flow being to achieve warming of the coldest low pressure refrigerant;
orb) from a compressor high-pressure refrigerant line between the compressor and an entrance to the high pressure line of the refrigeration process, and to a suction line of the compressor;
orc) from a point in the refrigeration process where high pressure refrigerant is at its coldest temperature, and to a point in the refrigeration process where low pressure refrigerant exits the coldest of the at least one heat exchangers in the refrigeration process, bypassed refrigerant not passing through a heat exchanger between the point where high pressure refrigerant is at its coldest temperature and the point where low pressure refrigerant exits the coldest of the at least one heat exchanger.
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Abstract
Refrigerant freezeout is prevented, and temperature is controlled, by the use of a controlled bypass flow that causes a warming of the lowest temperature refrigerant in a refrigeration system that achieves very low temperatures by using a mixture of refrigerants comprising at least two refrigerants with boiling points that differ by at least 50° C. This control capability enables reliable operation of the very low temperature system.
102 Citations
21 Claims
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1. A very low temperature refrigeration system utilizing mixed refrigerants, the system comprising:
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a compressor in fluid communication with a refrigeration process, the refrigeration process including a high pressure line on a high pressure side of the refrigeration system between the compressor and an evaporator, a low pressure line on a low pressure side of the refrigeration system in a refrigerant return path between the evaporator and the compressor, and at least one heat exchanger cooling refrigerant in the high pressure line from refrigerant in the low pressure line; and a bypass circuit connected either; a) from a point in the refrigeration process where high pressure refrigerant flows, prior to where the high pressure line exits a cold end of the refrigeration process, and to a point in the refrigeration process where the coldest low pressure refrigerant in the system flows, the bypass circuit including a valve controlling bypass flow of bypassed refrigerant, the result of the bypass flow being to achieve warming of the coldest low pressure refrigerant;
orb) from a compressor high-pressure refrigerant line between the compressor and an entrance to the high pressure line of the refrigeration process, and to a suction line of the compressor;
orc) from a point in the refrigeration process where high pressure refrigerant is at its coldest temperature, and to a point in the refrigeration process where low pressure refrigerant exits the coldest of the at least one heat exchangers in the refrigeration process, bypassed refrigerant not passing through a heat exchanger between the point where high pressure refrigerant is at its coldest temperature and the point where low pressure refrigerant exits the coldest of the at least one heat exchanger. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A refrigeration system, the system comprising:
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a compressor; a refrigeration process in fluid communication with the compressor, the refrigeration process including a high pressure line on a high pressure side of the refrigeration system between the compressor and an evaporator, a low pressure line on a low pressure side of the refrigeration system in a refrigerant return path between the evaporator and the compressor, and at least one heat exchanger cooling refrigerant in the high pressure line from refrigerant in the low pressure line; an expansion device receiving high pressure refrigerant from the refrigeration process; and a bypass circuit bypassing at least a portion of the refrigeration process and being connected to flow refrigerant into a point in the refrigeration process, the bypass circuit including a valve controlling bypass flow of bypassed refrigerant, the result of the bypass flow being to achieve warming of the coldest low pressure refrigerant in the system; the system using the mixed refrigerant to provide refrigeration at temperatures below 183K. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification