Computer simulation of heat and mass transfer in a cross flow parallel-plate liquid desiccant-air dehumidifier

Abstract

A MATLAB program using finite difference technique is investigated to predict the distribution of air stream parameters as well as desiccantsolution parameters inside the parallel plate absorber. The present absorber consists of 14 parallel plates with a surface area per unit volume ratio of 80 m2/m3. Calcium chloride as a liquid desiccant flows through the top of the plates to the bottom while the air flows through the gap between the plates making it a cross flow configuration. The model results show the effect of desiccant mass flow rate on the performance of the dehumidifier (moisture removal rateand the effectiveness). The results show that the maximum temperature and humidity ratio differences of the air are 2.56 °C and 11 g/Kg with a maximum solution mass flow rate of 160 g/s. The maximum temperature and minimum concentration differences of solution in the direction flow of solution are 3.185 °C and 0.34 % with a maximum solution mass flow rate of 160 g/s. The moisture removal rate increases rapidly with solution flow rate from 1.41 to 2.196 g s−1, but the moisture removal stagnates at high desiccant solution mass flow rates. The effectiveness achieves an increase of 0.39-0.66 when the solution mass flow rate increases from 30 to 160 g s−1.