A Tubed, Volumetric Cavity Receiver Concept for High Efficiency, Low-cost Modular Molten Salt Solar Towers

Small molten salt modular towers linked together to feed into a large power block, including storage, offer the potential to significantly reduce the cost of solar thermal energy. This is primarily through the significant increase in solar field and receiver efficiency that are achieved while still retaining the benefit of scale in the power block. Such towers would use cavity type receivers that are inherently more efficient than an external receiver. This paper examines the potential for a new concept for a cavity receiver, suitable for molten salt,which can increase efficiency and reduce metal hot-spot temperatures. By distributing the tubes within the volume of the cavity and arranging for the cooler inlet tubes to take the highest flux, the metal temperatures can be reduced close to the outlet salt temperature. The proposed design concept has the potential to solve a number of design issues that increase the cost of receiver systems. The paper provides a first-stage, simplified, theoretical analysis to show how receiverefficiency (from a radiative perspective) and hot-spot temperatureare affected by the number of heat transfer layers and the degree to which each layer blocks the radiation. The work shows promising results that needs to be taken forward in a number of areas.