Performance assessment of an improved open volumetric receiver design with 240 MWth

Abstract

Due to their proved robustness, good operating characteristics and the easy way to include thermal storage open volumetric receivers with air as heat transfer fluid are an interesting alternative for central receiver power plants. This alternative represents a significant step forward in plant availability and technical controllability to achieve the terminal goal of high probabilities and expectancy levels of annual electric yields representing the basis for the competitiveness and dissemination of dispatchable solar thermal systems. Though high availability has been shown in demanding transient and part load cases a permanent goal is to increase further efficiencies for future commercial scale receivers. In the current study a novel receiver design for a 240 MWth solar tower is presented which was optimised for reduced radiative losses and high air return ratios - a crucial parameter for obtaining high efficiencies of open volumetric receivers. With the help of a CFD model, which was recently specifically developed for the simulation of open volumetric receivers, the performance of the new receiver design was assessed. Under design conditions of 670°C hot air and 270°C return air temperature the receiver efficiency based on the intercept on the absorber reaches 84.3% and the air return ratio reaches 84.8%. At reduced hot air temperature of 560°C the efficiency even exceeds 90%.