A 2-TEMPERATURE MODEL OF THE REGENERATIVE SOLID-VAPOR HEAT-PUMP

A thermally driven heat pump using a solid/vapor adsorption/desorption compression process is thermodynamically analyzed. Heat regeneration between the two adsorbent beds is accomplished through the use of a ci rculating heat transfer (HX) fluid. Effective heat regeneration and sy stem performance requires that steep thermal profiles or waves be esta blished in the beds along the path of the HX-fluid flow direction. Pre vious studies by Shelton, Wepfer, and Miles have used square and ramp profiles to approximate the temperature profiles in the adsorbent beds , which, in turn, enable the thermodynamic performance of the heat pum p to be computed. In this study, an integrated heat transfer and therm odynamic model is described The beds are modeled using a two-temperatu re approach. A partial differential equation for the lumped adsorbent bed and tube is developed to represent the bed temperature as a functi on of time and space (along the flow direction), while a second partia l differential equation is developed for the heat transfer fluid to re present the fluid temperature as a function of time and space (along t he flow direction). The resulting differential equations are nonlinear due to pressure and temperature-dependent coefficients. Energy and ma ss balances are made at each time step to compute the bed pressure, ma ss, adsorption level, and energy changes that occur during the adsorpt ion and desorption process. Using these results, the thermodynamic per formance of the heat pump is calculated. Results showing the heat pump 's performance and capacity as a function of the four major dimensionl ess groups, DR, Pe, Ri, and KA(r), are presented.