Estudo experimental e desenvolvimento de um modelo de simulação de um refrigerador por absorção de pressão total única

Abstract

The main purpose of this work is the development of a steady-state model of a constant total pressure ammonia absorption refrigerator (diffusion absorption refrigerator - DAR). The model was validated in a test bank instrumented with fifteen thermocouples placed at the ends of the components of a commercial refrigerator with nominal electric power of the vapor generator equal to 80 W. A series of tests in dynamic and steady-state operation was carried through for the refrigerator operating with powers between 40 W and 80 W and room temperatures between 20°C and 30°C approximately. The dynamic tests had showed that the evaporator initiated the cooling process fifteen minutes after the vapor generator start-up. The results of the steady-state had been compared to the model results. This comparison showed a good model precision. The average errors between experimental and theoretical evaporation temperatures were of 2°C. Additional simulations had been carried through with the model in order to study the behavior of the total pressure and the performance coefficient (COP) of the refrigerator for different vapor generator powers. These simulations had showed that the COP increases with the reduction of the power. However, the use of powers below of 80W is not recommended due to increased of the evaporator time delay in the stage of refrigerator start-up.