Influence of thermodynamic and thermophysical properties of water-based working fluids for bubble pump operated vapour absorption refrigerator

Abstract

Miniaturization of the absorption refrigerator requires an air cooled absorber and condenser and replacement of the customary solution pump by a bubble pump. The operating pressures in the bubble pump operated two fluid vapour absorption refrigerator have to be very low (vacuum) so as to make use of the hydrostatic principle to maintain the required pressure difference between the condenser and evaporator. Hence, only water and alcohol based working fluid combinations are found suitable. Thermodynamic properties, such as specific heat and heat of mixing, and thermophysical properties, such as vapour pressure, density, viscosity, surface tension and solubility, are necessary for the overall performance evaluation of such a refrigerator. In this paper, sixteen water based working combinations have been analyzed and compared with reference to the solution density governing the hydrostatic height, viscosity and specific heat affecting the heat and mass transfer and solubility to avoid crystallization.