| In the common vapor compression refrigeration cycle, the compressor transports refrigerant vapor from the low pressure evaporator to the high pressure condenser. This function can also be accomplished through the alternate heating and cooling of solid adsorbent beds exposed to the refrigerant and connected via check valves to the evaporator and condenser. To heat and cool the solid adsorbent, a heat transfer fluid is pumped through a circuit consisting of the two beds, a fluid cooler, and a fluid heater. This heat transfer fluid passes through tubes which are embedded in the solid adsorbent. The system performance can be improved if thermal energy stored in the "hot" bed is recovered and used in heating the "cold" bed. This regeneration of heat can be accomplished if a steep axial temperature profile exists in the fluid passing through the bed.; To analyze the performance of this system, a one dimensional model of the transient heating and cooling of the solid adsorbent beds was used. The resulting system of two second order nonlinear partial differential equations were solved numerically to obtain the transient bed and fluid axial temperature profiles. The solution obtained in this work includes conduction, convection, mass transfer, and thermal capacity in both the fluid and solid.; Knowledge of the transient temperature profiles in the solid adsorbent bed permits calculation of the refrigerant adsorption in the bed. From these adsorption profiles, the refrigerant flow to the condenser and from the evaporator can be determined. The fluid cooler heat output and heater heat input can also be calculated from the transient heat transfer fluid temperatures exiting the beds. With this information the system coefficient of performance (COP) is calculated.; It was determined that there are bed designs that result in steep axial temperature gradients in the heat transfer fluid. These "thermal waves" permit energy stored in the "hot" bed to be recovered and used in heating the "cold" bed. The solid adsorbent heat pump thermodynamic system model developed in this work shows that the potential for high COP's exists. In addition, the model shows that the operating characteristics of the solid adsorbent heat pump are favorable. |
