EXPERIMENTAL STUDY ON A CASCADE CHILLER FOR AIR CONDITIONING APPLICATIONS

Cascade chillers realised through a connection of a thermally driven chiller and a vapour compression one allow exploiting the favourable features of both systems. In the present work, the experimental characterization of such a cascade is presented. It was performed by means of a testing rig suitable for the testing of thermally driven systems and the effect of operating conditions on the performance of the cascade was evaluated. The savings due to the operation of the cascade were calculated and the reduction in electric consumption with respect of the vapour compression system only were estimated in up to 40%. Moreover, a basic thermodynamic model was developed to evaluate different natural refrigerants. The theoretical study revealed that a performance up to 110% higher with respect to traditional chillers could be obtained if the cascade was used in refrigeration applications with R290 as refrigerant.