Investigation on the thermal hydraulic characteristics of sodium-supercritical CO2 in compact heat exchange channel

•Validation of numerical models is presented by comparison with experimental results.•Influence of turbulence Prandtl number model and turbulence model is analyzed.•Effects of structural parameter on thermal hydraulic performances are discussed.•Effects of flow parameter on thermal hydraulic performances are analyzed. Sodium-cooled fast reactor coupled with supercritical CO2 Brayton cycle has broad development prospects owing to the high thermal efficiency, smaller components and compact footprint. As one of the key components, sodium-supercritical CO2 compact heat exchanger plays a vital role in improving the operation performance of coupled power systems. In this paper, a numerical model for coupling heat transfer of sodium-supercritical CO2 in a straight-channel compact heat exchange channel is established and the prediction accuracy of the model is verified with experimental results. The influence of structural parameters and flow parameters on the resistance characteristics and heat transfer performance of cold and hot channels is systematically analyzed. The results show that the structure of semi-circular cross-section with an ABAB layout performs best in heat transfer performance. For the sodium channel, performance evaluation criteria gradually grow with the increase of sodium inlet velocity and slowly decline with the supercritical CO2 inlet velocity. For the supercritical CO2 channel, performance evaluation criteria decrease with the increase of sodium inlet velocity and increase with the supercritical CO2 inlet velocity. Reducing the supercritical CO2 inlet temperature could effectively improve the thermal hydraulic performance of the sodium-supercritical CO2 compact heat exchange channel.