What is Effective Thermal Conductivity

The heat transfer performance of supercritical CO2 (sCO2) in straight and three enhanced tubes were presented firstly, and then a distributed coordination principle was proposed for the design and optimization of heat exchangers. The field synergy principle could explain the thermal-hydraulic performance of sCO2 in different channels very well. The ratio of secondary number to Reynolds number Se/Re could give great predictions for the buoyancy effect. The local heat transfer coefficient also has a lot to do with the near-wall effective thermal conductivity. Zigzag channels with bend angles between 110° to 130° exhibit the best comprehensive performance. With smaller curvature diameter or larger camber, the serpentine channel has better overall performance. Two novel fins were proposed to further improve the performance of PCHE. The heat exchanger performance depends not only on the values of parameters but also on their distributed coordination, which provides a novel approach to heat exchanger optimization of sCO2 through the coordination improvement of distributed parameters.