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In the last years, it has been experimentally proven that the precursors of synthetic fuels can be produced exploiting the thermochemical water and CO2 splitting process, driven by concentrated solar radiation. This process requires large amount of thermal energy at very high temperature levels (1300-1400°C) far from being obtainable with conventional commercial receivers. For this reason, Synhelion SA is developing an innovative receiver design capable of operating at very high temperatures (in the order of 1500°C). To assist the design phase of the receiver, a CFD model was developed and exploited to run some CFD simulations campaigns. At first, an analysis on the effect of modeling the receiver behavior with different turbulence models (realizable k-ε and k-ω SST) was conducted with the aim of determining the most suitable for the cases under investigation. The CFD model was then applied to study the receiver behavior under different operating conditions. In particular, in terms of receiver operating pressure, two different cases were considered: ambient pressure and 10 bar. For each of them, a specific receiver design was described, and a relative simulations campaign, assuming different values of heat transfer fluid (HTF) mass flow rates, was performed not only to evaluate its thermo-fluid dynamics behavior but also to determine the most promising HTF inlet configuration between the two proposed of single and double inlets. Based upon the results obtained, the absorbing gas receiver resulted to have promising performance for all the working conditions evaluated. In the case of receiver operating at ambient pressure, the best resulting thermal efficiency values were in the range of 0.78 and 0.43, with relative HTF outflow temperature range of 1200°C and 1800°C. While, in the case of pressurized receiver, the best resulting efficiency values were in the range of 0.88 and 0.54, with relative HTF outflow temperature range of 1000°C and 1670°C. [ABSTRACT FROM AUTHOR]

Concentrating photovoltaic (CPV) cells offer higher efficiencies with regard to the PV ones and allow to strongly reduce the overall solar cell area. However, to operate correctly and exploit their advantages, their temperature has to be kept low and as uniform as possible and the cooling circuit pressure drops need to be limited. In this work an impingement water jet cooling system specifically designed for an industrial HCPV receiver is studied. Through the literature and by means of accurate computational fluid dynamics (CFD) simulations, the nozzle to plate distance, the number of jets and the nozzle pitch, i.e. the distance between adjacent jets, were optimized. Afterwards, extensive experimental tests were performed to validate pressure drops and cooling power simulation results. [ABSTRACT FROM AUTHOR]