Mathematical modelling and performance analysis of a novel auto-cascade refrigeration cycle for ultra-low temperature applications

The main objective of this study is to assess both energetically and exergetically the performance of a novel auto-cascade refrigeration (NACR) cycle enhanced by an internal heat exchanger using R290/R170. In contrast to the ACR cycle with a -60 degrees C evaporation temperature, the NACR cycle displays a COP increase of 140.78% and a 148.67% improvement in exergy efficiency. Additionally, there is a notable decrease of 13.77% in compressor discharge temperature. For an evaporation temperature of -55 degrees C, the NACR cycle achieves a COP of 0.403 and an exergy efficiency of 14.61%, with the compressor discharge temperature registering at 126.60 degrees C.