Investigation of two-stage cascade refrigeration systems from an energy and exergy point of view

Vapour compression cascade refrigeration systems are comprised of two or more systems that are coupled to each other in which the evaporator of the higher stage refrigeration system serves as a condensing medium for the lower stage system. Vapour compression cascade refrigeration systems are used to achieve low temperature refrigeration and are used for applications down to -80°C. In this study, a two-stage vapour compression cascade refrigeration system was modelled from a thermodynamics point of view including first and second law of thermodynamics. R134A was used as the refrigerant in the higher stage system and R404A was used in the lower stage refrigeration, and they were experimentally investigated according to different condenser temperatures ranging from 47°C and 57°C. The results obtained were inserted into a computer program developed with the help of Engineering Equation Solver (EES). It showed that the coefficient of performance of two-stage vapour compression refrigeration system decreased by 8% and the total amount of exergy destruction decreased by 50%.