A thermally driven flat plate air gap membrane distillation liquid desiccant regenerator for lithium chloride in dehumidification applications is modeled. Operating conditions and device geometry are optimized, and it is found that membrane materials have little influence on regenerator performance. It is shown that radiation heat transfer across the air gap cannot be neglected. The regenerator removes 11.4 g min(-1) cm(-3) of moisture with a COP 01 0.372 for an inlet solution concentration of 0.38, solution flow rate of 50 ml min(-1), and heated solution temperature of 135 degrees C. This design has negligible desiccant carry-over losses and operates without a blower. (C) 2011 Elsevier Ltd. All rights reserved.