“…These efforts have been categorized into areas of materials and geometry, numerical modeling, and experimental measurement 17,23,29,32,35 . A NASA regenerator research grant effort led by Cleveland State University, with subcontractor assistance from the University of Minnesota, Gedeon Associates, and Sunpower Inc. has been providing computational and experimental results to support definition of various empirical parameters and "closure" relations needed in defining a thermal, non-equilibrium, macroscopic, porous-media model for use in multi-D Stirling codes for regenerator simulation 33 .…”