Numerical Study on Heat Transfer and Frictional Resistance of Two Types of Molten Salts in Straight Channels and Supercritical Carbon Dioxide in Airfoil Channels

Molten salt and supercritical carbon dioxide (sCO₂) are considered to be one of the most promising combined heat transfer refrigerants for third-generation solar thermal power generation. To evaluate the potential of chloride salts and carbonates in third-generation solar thermal power generation, this paper uses molten salts and sCO₂ as the working media of printed circuit board heat exchangers (PCHE), and uses numerical simulation to study the heat transfer and friction of PCHE channels with different molten salts and sCO₂, and establishes predictive correlations respectively. A local heat transfer and friction study was conducted on the sCO₂ side of the airfoil channel, and it was found that the inlet mass flow rate has a significant impact on it, while the inlet temperature has a relatively small impact. A comprehensive comparison was made between the heat transfer and friction of two molten salts, and the comprehensive performance of chloride salts was 70%–80% higher than that of carbonates. The results indicate that the potential of chloride salts in third-generation solar thermal power generation is much greater than that of carbonates.