Heat and mass transfer of the new LiBr-based working fluids for absorption heat pump

Abstract

The heat and mass transfer characteristics of water vapor absorption into the LiBr-based working fluids were experimentally investigated using both static pool and falling film type absorbers. The working fluids treated in this study are the commonly used LiBr + water and two newly developed ones with LiBr + 1,3-propanediol + water and LiBr + LiI + 1,3-propanediol + water solutions. To enhance the water vapor absorption rate, two surfactants of n-octanol and 2-ethyl-1-hexanol were tested over a wide range of concentrations. The absorption behaviors of three working fluids observed from two different types of absorber were discussed in connection with the thermophysical and transport properties of each working fluid. Considered in the aspect of operating range and heat and mass transfer characteristics, the LiBr + LiI + 1,3-propanediol + water solution with 2-ethyl-1-hexanol could be a promising working fluid-additive pair as an alternative to the LiBr + water solution.