A generalized moving-boundary algorithm to predict the heat transfer rate of transcritical CO2 gas coolers

Abstract This paper presents the development of a CO2 gas cooler model using the moving-boundary (MB) method. The model aims to separate the gas cooler into two regions, supercritical and supercritical liquid, to predict the steady-state thermal heat transfer rate for air-type CO2 heat exchanger. The model uses the latest correlations for refrigerant and air-side heat transfer coefficients and pressure drops. The experimental results of fin-and-tube type and micro-channel type gas coolers were used for model validation. The mean absolute error (MAE) of the gas cooler heating capacity predictions was approximately 4%, while the predictions of the outlet temperature of the refrigerant side were within  ± 3 K. The present MB model also showed an improved computational time of up to 10 times faster compared to a discretized model, which can reduce the overall computational effort in the simulation of detailed transcritical cycle model.