Predicted performance of a ceramic foam gas phase heat recuperator for a solar thermochemical reactor

The efficiency of solar thermochemical cycles to split water and carbon dioxide depends in large part on highly effective gas phase heat recovery. Heat recovery is imperative for approaches that rely on an inert sweep gas to reach low partial pressures of oxygen during thermal reduction and/or use excess oxidizer to provide a higher thermodynamic driving potential for fuel production. In this paper, we analyze heat transfer and pressure drop of a tube-in-tube ceramic heat exchanger for the operating conditions expected in a prototype solar reactor for isothermal cycling of ceria. The ceramic tubes are filled with reticulated porous ceramic (RPC). The impacts of the selection of the composition and morphology of the RPC on heat transfer and pressure drop are explored via computational analysis. Results indicate a 10 pore per inch (ppi), 80-85% porous alumina RPC yields effectiveness from 85 to 90 percent.