A novel ultra-low temperature cascade refrigeration with dual auxiliary loop to enhance thermal performance.

A novel kind of cascade refrigeration cycle for ultra-low temperature applications has been proposed in the present work to enhance thermal performance with reduced carbon footprints more economically. The conventional cascade refrigeration system (CCRS) has been modified, implementing a single auxiliary cycle (CRSAC) and dual auxiliary cycle (CRDAC) between HT and LT cycle and their performances are compared with CCRS and cascade refrigeration system with mechanical precooling (CRMP). The implementation of auxiliary cycles enables the modified cascade refrigerators to operate with lower compression ratio. The CRDAC cycle consumes 24-40% less energy than CCRS, 51-68% less than CRMP, and 23-38% less than CRSAC. Keeping the condenser temperature fixed at 318 K, varying the evaporative temperature from 193 to 220 K, the COP values of CRDAC, CRSAC, CRMP, and CCRS vary from 1.245 to 2.181, 0.89 to 1.41, 0.44 to 0.64, and 0.68 to 1.1 respectively. The CRDAC cycle provides approximately 40%, 62%, and 32% lower TEWI values and 13%, 25%, and 33% fewer E.I.I. values than CCRS, CRMP, and CRSAC cycles. Under the same operating conditions, the CRDAC cycle runs at 30-41% lower operational cost than CRSAC, 35-68%, and 37-60% lower than CRMP and CCRS, respectively.