Computational fluid dynamics study to reduce heat losses at the receiver of a solar tower plant

Abstract

Today, renewable energy systems are developing rapidly and are reaching economic competitiveness with conventional power plants. Due to their ability to efficiently integrate energy storage systems, concentrated solar power plants are ascribed a high potential for energy generation. Typically, the usage of molten salt as heat transfer fluid in the receiver reaches thermal efficiencies of 80–88% (de Meyer et al., 2016. Thermal Resistance Model for CSP Central Receivers). Placing the dome on top of the tower may be a measure in order to reduce the heat losses at the receiver. In the presented work, a computational fluid dynamics 11Computational fluid dynamics.(CFD) study with the commercial simulation package STAR-CCM+ 22Simulation of Turbulent flow in Arbitrary Regions - Computational Continuum Mechanics - C++ based.(Simulation of Turbulent flow in Arbitrary Regions - Computational Continuum Mechanics, C++ based) was executed to investigate the impact of placing the dome geometry on top of the solar tower. Mainly the potential to reduce convective and radiative heat losses at the molten salt receiver at various wind loads was analyzed. The respective Crescent Dunes plant in Las Vegas (Nevada) with an electrical net power of 110 MW was chosen as reference for generating the required input data for the simulations. Overall six simulation models were set up: two geometries, one with and one without a dome, and each of the geometries with three variable wind loads (Beaufort Number (BN 33Beaufort Number.) 2, 4 and 6). In the main part, the radiative and convective heat losses at the receiver were analyzed for the BN 4 and afterwards compared to the results with the models BN 2 and BN 6. The construction of the dome reduced the heat losses at the receiver by 1.92 MW (BN 4) with the radiation energy savings (1.32 MW) being higher than the reduction of convective losses (0.60 MW). Furthermore, the reduced heat losses are 1.79 MW for BN 2 and only 0.43 MW for BN 6. Besides in the last case, the convective losses actually rise and the function of the dome turns out as counterproductive. Nevertheless, the results can be fundamental for further research projects as the dependence of the heat losses on variations of the dome form and the installation of components to disturb or eliminate a convective heat flow at the receiver can be essential to future studies. However, each concept must be seen in terms of economic and technical feasibility.