Journal of Supercritical Fluids, Vol.148, 104-115, 2019
Studies on the thermal-hydraulic performance of zigzag channel with supercritical pressure CO2
The numerical investigations of zigzag channel showed that the reduction of the zigzag bend angle improves heat transfer performance but worsens hydraulic performance. The heat transfer enhancement has much to do with the decrease of the entropy generation and the increase of the synergy between the velocity and the temperature gradient. The larger heat effectiveness corresponds to better convective heat transfer effectiveness, and a very small heat capacity ratio could lead to slight reduction of the heat effectiveness. The reverse flow boosts the field synergy and diminishes the heat transfer entropy generation, and the secondary flow would improve the synergy between the velocity and temperature gradient in zigzag channels as well as enlarges the entropy generation near the wall. The zigzag channels with the bend angles between 110 degrees to 130 degrees show the best comprehensive performance in terms of both the first and second laws of thermodynamics.