Studies on High Efficiency Absorption System Using Ethylamine + Water + Lithium Bromide

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This investigation was undertaken to examine whether the ethylamine + water + lithium bromide system (water : lithium bromide=2 : 1 mass) is suited for absorption refrigerating machine and heat pump. The physical properties (density, viscosity, surface tension, vapor pressure and vapor-liquid equilibrium) and the thermal properties (heat capacity and integral enthalpy of mixing) of lithium bromide + ethylamine aqueous solutions were measured. Measurements of density, viscosity, surface tension, vapor pressure, vapor-liquid equilibrium and heat capacity were carried out at various temperatures and ethylamine concentrations. The integral enthalpies of mixing at 278.15K were obtained for solutions whose ethylamine concentrations ranged from 10-70wt%. The empirical formulae for vapor pressure, heat capacity and integral enthalpy of mixing were obtained from experimental data.Theoretical calculations of the coefficients of performance were undertaken to examine the performance characteristics of this system. The coefficients of performance for absorption refrigerating machines and absorption heat pump were calculated using the enthalpies at various temperatures, pressures and ethylamine concentrations. The performance characteristics of this system were compared with that of the ethylamine + water system. This system was found to be suitable for an air-cooled single-stage absorption refrigerating machine and a single-stage absorption heat transformer.