Numerical study on thermal performance and thermal stress of molten salt receiver tube based on induction heating

Abstract

Induction heating is an emerging research method that can recreate half-perimeter heating of a receiver tube in a tower-concentrating solar power plant. In this study, a three-dimensional (3D) field numerical model that couples electromagnetic induction, heat transfer, and turbulence, is developed to study the thermal performance of a receiver tube during the preheating process and under salt circulation conditions. The effects of the coil-to-tube distance, coil power, molten salt inlet temperature, molten salt inlet velocity, and ambient temperature were investigated. Furthermore, the thermal stress distribution and evolution in the tube were calculated. The heat generation was fund to be concentrated on the outer surface of the tube front. The increase in coil power significantly accelerated the preheating process. With increase in the coil power from 200 to 500 W, the time required for the maximum tube temperature to reach 350 °C reduced by 55.67 %. The heating efficiency increased with increasing coil power, molten salt inlet velocity, and ambient temperature decreased with increasing coil-to-tube distance and molten salt inlet temperature. Among them, the molten salt inlet temperature had a more significant effect. As it increased from 250 to 400 °C, the heating efficiency decreased from 47.17 to 18.82 %. The maximum and minimum equivalent thermal stresses at preheat stabilization were reached at θ = 0° and θ = 45°, respectively. Furthermore, the equivalent thermal stress at preheat stabilization differed from that with salt circulation by only 4.46 %.