A simplified model of heat and mass transfer between air and falling-FLM desiccant in a parallel-plate dehumidifier

A simplified model is developed to predict the heat and mass transfer between air and falling-film liquid desiccant during dehumidification in a parallel-plate absorber. Compared to second-order partial differential equations that describe fluid motion, first-order, non-coupled, ordinary differential equations are used to estimate the heat and mass transferred and explicit equations are derived from conservation principles to yield the exiting absorber conditions for different flow arrangements. The model uses a control volume approach that accounts for the change in film thickness and property values. The model results were within 5% of a more complicated parallel-flow model in literature. Using existing experimental data for a counterflow absorber, the model uncertainty was determined and the model was validated at the level of 8.5% for varying inlet desiccant mass flow rates and 11% for varying inlet air mass flow rates.