Two stage refrigeration plant having a plurality of first stage refrigeration systems

Claim 1

A two stage refrigeration plant having a plurality of first stage change of phase refrigeration systems and at least one second stage liquid coolant circulation system comprising: a first first stage change of phase refrigeration system including; a change of phase refrigerant, a first compressor, a first condenser, a first evaporator, a first high pressure hot gas supply line running from said first compressor to said first condenser, a first liquid refrigerant supply line running from said first condenser to said first evaporator, a first metering device in said first liquid refrigerant supply line capable of controlling the flow of refrigerant to said first evaporator in accordance with the requirements of said first evaporator, a first low pressure supply line running from said first evaporator to said first compressor thereby completing the circulation circuit for said first refrigeration system; a second first stage change of phase refrigeration system including; a change of phase refrigerant, a second compressor, a second condenser, a second evaporator, a second high pressure hot gas supply line running from said second compressor to said second condenser, a second liquid refrigerant supply line running from said second condenser to said second evaporator, a second metering device in said second liquid refrigerant supply line capable of controlling the flow of refrigerant to said second evaporator in accordance with the requirements of said last mentioned evaporator, a second low pressure gas supply line running from said second evaporator to said second compressor thereby completing the refrigerant circulation circuit for said second change of phase refrigeration system, a second stage liquid coolant circulation system including; a liquid coolant a liquid coolant circulation pump, a space cooling element, a first liquid coolant chilling element in heat transfer relationship with said first evaporator, a second liquid coolant chilling element in heat transfer relationship with said second evaporator, a selector valve having a liquid coolAnt inlet and two liquid coolant outlets either or both of which outlets may be selectively placed in communication with said inlet by actuation of said selector valve, a first liquid coolant supply line running from said pump to said space cooling element, a second liquid coolant supply line running from said space cooling element to said selector valve inlet, a third liquid coolant supply line running from the first of said two liquid coolant outlets to said first liquid coolant chilling element, a fourth liquid coolant supply line running from the second of said two liquid coolant outlets to said second liquid coolant chilling element, a fifth and sixth liquid coolant supply line connecting said first liquid coolant chilling element and said second liquid coolant chilling element respectively to said circulation pump to thereby complete the liquid coolant circulation circuit, means for actuating said selector valve to place said second liquid coolant supply line in communication with either or both of said third and fourth liquid coolant supply lines to thereby place one or more of said liquid coolant cooling elements in said liquid coolant circulation system.