Ahmad Reza Rahmati - Department of Mechanical Engineering, University of Kashan, Iran
Ali Gheibi - Department of Mechanical Engineering, University of Kashan, Iran

Performance of a two-stage multi-inter-cooling trans-critical CO۲ refrigeration cycle containing internal heat exchanger, two intercoolers, ejector, and separator, has been analyzed after modification. In the present study, an internal heat exchanger has been included within this cycle for possible improvement in its cooling performance. The impacts of operational parameters such as gas cooler and evaporator temperatures and gas-cooler pressure, on cycle performance have been investigated. Results are validated against those available in the literature. Comparisons of the results show that there is excellent agreement between them. Obtained results showed that modified cycle improved the maximum coefficient of performance (COP max), by ۲۰.۵۸% compared to the internal heat exchanger two-stage TRCC cycle and ۲۳.۲% compared to multi-inter-cooling two-stage TRCC cycle with ejector expansion device. Also, the total exergy destruction rate of the improved cycle is between its rates of two original cycles.

Ejector-expansion, Internal heat exchanger, Refrigeration, Two-stage, Transcritical