air-chiller comprises a primary compressor that circulates a mixture of four refrigerants with different boiling points through a primary condenser and several heat-exchanger coils in series. Each heat exchanger coil includes a large section of tubing in which are disposed four smaller sections of tubing. Two of these smaller sections of tubing carry the air to be chilled. The other two smaller sections of tubing carry high pressure refrigerants from the compressor and condenser. The remaining inside volume of the large section of tubing provides for the suction-return of heat-laden refrigerants.
Input air passes through the four heat exchangers in series and comes out the fourth one highly refrigerated. The high-pressure refrigerant coming out of the primary compressor is chilled below ambient temperature by a secondary refrigeration sub-system. Such is circulated, after drying, through an auxiliary condenser for additional refrigeration before going to work in the first heat-exchanger coil. The secondary refrigeration sub-system further includes a small compressor that circulates a single HP80 refrigerant through the auxiliary condenser..
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