A correlation-free on-line optimal control method of heat rejection pressures in CO2 transcritical systems

This paper proposes a novel correlation-free on-line optimal control method for CO₂ transcritical refrigeration systems. It uses the on-line correction formula to track the optimal pressure set point. As a critical advantage against the existing empirical correlations of the heat rejection pressure, it is independent of the cycle, the system specifications, and the operating conditions. Dynamic numerical simulation demonstrates how to apply the new method to a basic CO₂ transcritical refrigeration system. The results show that the proposed method can well track the optimal pressures and is robust to resist the sampling noise.