UNSTEADY NUMERICAL SIMULATION OF DYNAMIC REACTOR - EVAPORATOR INTERACTION IN THERMOCHEMICAL REFRIGERATION SYSTEMS

Close interaction between evaporation/reaction rates in gas-solid refrigeration cycles promotes the dynamic behavior of gas pressure in gas-liquid and gas-solid interfaces in evaporators and reactor diffusers. Simultaneously, gas pressure modifies both reaction rates in reactors and mass and energy transfer rates in reactors and evaporators. The objective of this work is to model the complex interaction between reactor and evaporator using a phenomenological approach. The coupled interaction is studied by a novel mathematical model of the reactor and evaporator at the synthesis/evaporation step. The model of the gas-solid reactor is based on unsteady 2-D mass, momentum and energy transport equations. The evaporator model considers the interaction between evaporation/reaction rates given by the unsteady mass and energy transfer at heterogeneous interfaces and with other components. The thermodynamic properties of the refrigerant are calculated by the Patel-Teja equation-of-state. Simulation results predicted by the model were satisfactorily validated with experimental data. Predicted interaction between reactor, evaporator and cooling space showed non-linear behavior of gas pressure. The simulation results showed that, if the dynamics of the evaporator and cooling space are neglected, coefficient of performance (COP) is overestimated by 32% for the configuration evaluated in this work.