Modeling of heat and mass transfer in parallel plate liquid-desiccant dehumidifiers

In the last few years there has been renewed interest in solar driven air-conditioning. One concept that has been investigated is the use of liquid-desiccant cooling systems. Such systems have the advantage of improved humidity control, particularly in applications with high ventilation rates. Moreover, lower regeneration temperatures can be employed, allowing for a more efficient use of heat from low temperature sources, e.g., flat plate solar collectors. In the present work, mathematical and numerical models were developed for internally cooled liquid-desiccant dehumidifiers, using three different approaches. The first approach is based on heat and mass transfer correlations. The second one numerically solves, by the finite-difference method, the differential equations for energy and species assuming a constant film thickness. The third approach introduces a variable film thickness. All approaches assume fully developed laminar flow for the liquid and air streams. The variable thickness model results closely matched the experimental data available in the literature.