Proposal and sizing of a molten Salt-to-sCO2 heat exchanger in supercritical solar thermal power plants

Abstract

Solar Thermal Power Plants (STPPs), based on supercritical CO2 (sCO2) cycles, seem to be a promising alternative to increase the global solar-to-electric efficiency. The most conventional scheme for this technology is a molten salt (MS) central receiver, working at high temperature (above 700°C), coupled to the sCO2 cycle. For this scheme it is proposed a new design of the source heat exchanger that transfers the thermal energy from the molten salt to the CO2: the Compact Honeycomb Heat Exchanger (CHHE), in which the molten salt goes through a larger circular duct that is surrounded by 6 smaller trapezoidal ducts, through which the sCO2 circulates. This paper is focused in the thermal model of this new heat exchanger, and a thermo- economic optimization for a selected supercritical STPP.