Vacuum Desiccant Cooling for Personal Heat Stress Management

Abstract

The objective of this PhD project is to develop novel membranes and desiccants that would help develop a second generation vacuum desiccant cooling (VDC) garment that is efficient, robust, durable and wearer-friendly. It was found that properly chosen support material could improve both mechanical strength and vapor flux for flat sheet polyvinylidene fluoride (PVDF), due to improved membrane structure and structure integrity that enhanced vapour mass transfer. Super solid desiccants were developed using a super absorbent polymer (SAP), which are sodium polyacrylate granules, as the host matrices to harbour LiCl. Furthermore, a novel desiccant based on loading LiCl in to hydrophobic hollow fibre membranes and therefore called membrane based desiccant fiber (MDF), was developed and demonstrated to be suitable for VDC. Heat and mass transfer for vapor absorption in MDF were analyzed. These membranes and desiccants, although developed for application in VDC, may also found applications in other fields such as water treatment, air conditioning, and natural gas dehumidification. Finally, based on the newly developed membranes and desiccants, three conceptual designs of second generation VDC garments are proposed.