Energy and Exergy Analysis of a Cooling/Power Cogeneration Ejector Refrigeration System

The organic Rankine cycle is introduced into the conventional ejector refrigeration (CER) system to establish the low-grade heat-driven cooling/power cogeneration ejector refrigeration (CPC-ER) system using the isobutane as the refrigerant. In comparison with the CER system where external power is consumed by the circulating pump, the power output from the CPC-ER system is more than the power consumption of its circulating pump so that a portion of net power is derived from the CPC-ER system. Based on the mathematical model of thermodynamics, energy and exergy analysis of the CPC-ER system is carried out and compared with the CER system. The results reveal that the equivalent coefficient of performance (COP) of the CPC-ER system is 41.14% to 71.30% higher than that of the CER system, and the exergy efficiency of the CPC-ER system is 1.32 to 1.49 times higher than that of the CER system. Both the power produced by the turbine and the total exergy output from the CPC-ER system approach the maximum, as the generating temperature in the generator is up to 80°C. The CPC-ER system has the higher energy utilization efficiency than the CER system, and it is suitable for the cooling and power-required places with low-grade thermal sources.