| Modeling of and experiments with heat storage in regenerators packed with Phase-Change Material, scPCM, are discussed. The ideal Phase-Change Regenerator, scPCR, is presented. It is shown that two temperature fronts move through the bed at different velocities. The first and second law thermodynamic efficiencies for the ideal scPCR are presented. An expression for melting temperature which gives the maximum second law efficiency is developed.;Two algorithms are presented to solve the coupled partial differential equations for heat transfer and storage in the scPCR on the bed scale and on the scPCM scale. Both schemes discretize the bed via. the tanks-in-series approximation. In one scheme the pseudo steady-state assumption is applied to the scPCM scale. In the second scheme the scPCM scale is solved by orthogonal collocation applied to the equations, which are transformed to immobilize the melt/solid interface and to eliminate the effect of spherical geometry. The effects of physical properties varying with temperature are also incorporated. The models are found to compare well with each other. A series of parametric studies are presented, illustrating the effects of specific dimensionless groups.;Development of a novel scPCM is presented. It consists of n-octadecane retained by capillary forces in a porous silica support and changes from opaque to semitransparent when the wax melts. Results of differential scanning calorimetry experiments to quantify the scPCM are presented. The measured latent heat and melting point are lower than expected. An explanation for this phenomenon, based upon wax adsorption on the support surface, is suggested.;A laboratory scPCR which allows visualization of the melt front movement and measurement of the inlet and outlet gas temperatures is described. Experiments with heated or cooled CO... |
