Analytical Solutions of Air Refrigeration Cycle at Optimal Coefficient of Performance

Abstract:

A dimensionless thermodynamic model of single stage air refrigeration cycle was developed. Based on the model, analytical solution of the optimal pressure ratio at the maximum ε (coefficient of performance) was derived. So did the cycle key performance indices. Furthermore, numerical analysis using the analytical solutions was conducted to reveal the impact of operating conditions and component efficiencies on the cycle performance. The results show that bigger heat source temperature difference leads to higher optimal pressure ratio, higher cooling capacity, but lower ε. On the other hand, higher compressor/expander efficiencies result in less lower optimal pressure ratio, much higher ε and cooling capacity. Under the same conditions, the expander efficiency has more significant influence on the cycle performance than the compressor efficiency. The analytical solutions and corresponding conclusions are helpful in optimal design of air cycle refrigeration systems.