Numerical analysis of wavy PCHEs in supercritical CO2/propane mixture Brayton cycle

Abstract

The CO2/propane mixtures benefit the safe operation of the Brayton cycle while improving economic efficiency and mitigating environmental impacts. The performance of the heat exchanger has a significant impact on the effective operation of the cycle. However, research on heat exchangers in supercritical CO2/propane mixture Brayton cycles is still in the initial stages. The previous studies were conducted in straight-channel heat exchangers. In this paper, the thermal–hydraulic characteristics of CO2 and CO2/propane mixtures in the wavy printed circuit plate heat exchanger (PCHE) are numerically studied and compared under various operating parameters. In comparison to CO2, the fluid temperature of CO2/propane mixtures is higher, while the pressure loss is smaller. The Nusselt numbers of the cold and hot channel increase by at least 3.1% and 16.8%, respectively. Furthermore, this change becomes more pronounced as cold fluid mass flow and inlet temperature increase. The addition of propane is beneficial to the improvement of the flow and heat transfer performance of the wavy PCHE. New thermal–hydraulic correlations are proposed for these mixture-mixture wavy PCHEs. The prediction deviations of the new correlations are ± 4% for the Nusselt number and ± 2% for the Fanning coefficient.