Random and structured packings were studied with varying bed depths in the regenerator and the dehumidifier of a solar-assisted liquid-desiccant system. The slopes of the log−log plots of mass-transfer rate vs solution flow rate were found to be close to 0.8, which indicated that the conditions for the liquid phase were turbulent for the operating conditions in both contactors. The small intercepts obtained for the Wilson plots indicated that the gas-phase mass-transfer resistance was negligible compared to the liquid-phase mass-transfer resistance. Liquid-phase mass-transfer coefficients for the packed bed alone were obtained by separating the contributions of the other mass-transfer regions in the contactors. The random packing mass transfer coefficients varied from 0.48 to 2 mol/(s m2), while the double-layer, structured packing mass-transfer coefficients varied from 0.018 to 0.035 mol/(s m2). These mass-transfer coefficients were converted into a dimensionless form, utilizing experimentally obtained diffusivity values.

A relatively simple method was employed for measurement of water diffusivity in aqueous lithium bromide and lithium chloride solutions, The twin bulb apparatus used for these measurements was developed using an analogy between this apparatus and the conventional diaphragm cell apparatus. Tritiated water (TOH) was used as a tracer for these experiments because of its chemical similarity and proximity to the molecular weight of water. High tracer activity used at the beginning of the experiments allowed the use of relatively shorter time duration for each experiment ('" 20h) and a quasi-steady state equation to calculate the diffusivity from the observed tracer activity data.Initially, the water diffusivity in lithium bromide solutions for concentrations varying from 0.5 M to 3 M (22.1 weight percent) was measured to obtain a comparison with published values. The lithium bromide concentration was further varied from 3 M to II M (57.4 weight percent) to obtain data in the concentration range usually employed in absorption cooling applications, which is near the solubility limit. The water ditfusivity was found to vary with lithium bromide concentration, and to have a maximum of 16.7 x 10-10 m'ls at 4 M. These diffusivity values were also compared with those obtained using an equation proposed by Rosevaere et al. (1941) for non ideal solutions. The water diffusivity in lithium chloride solutions was measured at concentrations of 7 M (25.7 weight percent) and 8 M (28.87 weight percent) to obtain a comparison with published values. The lithium choride concentration was further varied from 8 M to 13 M (43.24) weight percent) to gather data beyond those of other researchers. Similar to the trend of water diffusivity in lithium bromide solutions, water diffusivity in lithium chloride solutions was also found to vary with concentration with a minimum of6.2 x 10-10 m 2/s near the solubility limit.