| The incorporation of the compressor and expander into one mechanism is a compact and useful method for recovering some energy from the expansion/throttling stage of the refrigeration cycle. This thesis aims to experimentally and theoretically investigate the performance of the overall refrigeration system with emphasis on the compressor-expander unit. Experimental work is carried out over several working conditions. An investigation in the related effects on the cycle COP, volumetric efficiency, compressor power loss and other system operating conditions is conducted as well. The experimental setup includes the compressor-expander, a condenser, a variable orifice expansion valve, an evaporator and an accumulator.;A compressor-expander theoretical model involving detailed modelling of the compressor-expander geometry and solving basic mass and energy conservation equations with justified assumptions is developed. Analytical models for the condenser, expansion device and evaporator work in tandem with the compressor-expander model to predict the fluid conditions in all parts and sections of the cycle. |
