Modeling of Metal Matrix Concentrated Solar Receivers for Supercritical Carbon Dioxide Power Blocks

Supercritical carbon dioxide (sCO₂) power blocks for concentrating solar power (CSP) with novel metal matrix solar receivers have the potential to reduce operating expenses while improving overall system efficiencies. These concentrated solar receivers integrated with a metal matrix-based phase change material (PCM) thermal storage medium provide the compounding effect of an efficient heat exchanger while also integrating thermal storage within the receiver. Detailed numerical modeling of such devices with enthalpy–porosity-based formulation for phase change and turbulent convective heat transfer for the sCO₂ microchannels is described in the current work. With sCO₂ power blocks operating at temperatures and pressures beyond 800 °C and 200 bar, different high-temperature PCMs are studied. Steady-state charging and discharging cycles in addition to transient charging are simulated to analyze the thermal performance of the device. Energy storage density of the PCM is evaluated by tracking the movement of the melt-pool interface along the streamwise direction in a highly corrugated wavy microchannel. A detailed scaling analysis carried out to estimate the order of magnitude of the heat transfer coefficients is found to agree well with the numerical predictions. The outcomes from the current work can be utilized for sizing and detailed design of integrated solar receivers for high temperature sCO₂ power block applications.