Analysis of a Flat-Plate, Liquid-Desiccant, Dehumidifier and Regenerator

Abstract

A numerical model for isothermal and non-isothermal flat-plate liquid-desiccant dehumidifiers and regenerators was developed and implemented. The two-dimensional model takes into account the desiccant, water and air flow streams. A parametric analysis was performed to evaluate the influence of some of the most important operational parameters on mass transfer performance, such as flow configuration, water mass flow rate and inlet temperature, and desiccant mass flow rate. The results indicate that the water temperature and mass flow rate have a strong effect on the performance of the dehumidifier and regenerator, with the isothermal wall case acting as an upper limiting case. Increasing the desiccant mass flow rate improves the water transfer performance, but the improvement is asymptotic with mass flow rate. An experimental rig with a single channel prototype was also built and tests were run for 18 different cases, with varying water mass flow rate, desiccant mass flow rate and flow configuration. The results show trends similar to those observed in the numerical results. However, the discrepancies between the numerical and experimental results are larger than the estimated experimental uncertainty at a 95% confidence level. There is some indication that poor desiccant wetting of the channel walls was partially responsible for the discrepancies.