Cycle parameter optimization of vortex tube expansion transcritical CO2 system

Optimization studies along with optimum parameter correlations are presented in this article for a vortex tube expansion transcritical CO2 refrigeration cycle with two cycle layouts based on the Maurer model (1999) and the Keller model (1997). A simple thermodynamic model is proposed and used for vortex tube analysis. Finally, the COP improvement and effect on optimum discharge pressure by using vortex tube in transcritical CO2 cycle instead of expansion valve are presented. The results show that the effect of cold mass fraction and inlet water temperature to desuperheater (used to cool hot gas from vortex tube) on the cycle optimization is negligible. The Maurer model is better than the Keller model in terms of moderately more COP improvement and lower cost due to less components. The use of a vortex tube is more effective for higher gas cooler exit temperature for both models. Results show that the vortex tube expansion transcritical CO2 cycle for the Maurer model can give higher COP improvement for lower cooling temperature applications; however the trend is reverse for the Keller model.