Performance assessment of a high temperature chloride salt absorber tube with a novel half wavy-strip

Currently, the concentrated solar power uses nitrate salt as heat transfer fluid. However, the operating temperature and net thermal-to-electric conversion efficiency are lower. Meanwhile, there are disadvantages in local high temperature and poor uniformity of wall temperature for absorber tube. To address this problem, a high temperature chloride salt absorber tube featuring a novel half wavy-strip is put forward and discussed numerically for the first time. Furthermore, the performance of absorber tube with half wavy-strip is evaluated under varying structural parameters and operation conditions. Results show that the half wavy-strip guides the periodic formation of two to four vortices in absorber tube, contributing positively to improved salt mixing and heat transfer. Consequently, the temperature uniformity is significantly enhanced and peak temperature is significantly reduced. Compared with smooth absorber tube, the peak temperature and temperature difference decrease by a maximum of 67.08 K and 67.38 K, respectively. Additionally, the friction factor and Nusselt number increase by 153–379 % and 22%–65 %, respectively. Furthermore, the highest reduction in rate of entropy generation is 31.55 % and the maximum improvement in exergy efficiency is 4.77 %. This research may provide guidance for designing the high temperature chloride salt absorber tube to ensure both efficient and safe operation.