Mass and Heat Transfer at Different Heat Exchange Surfaces and Their Suitability for Use in Thermal Desalination Plants

A new concept for small scale multi-stage distillation (MSD) desalination plants is presented allowing an installation in remote rural areal due to low maintenance, operating and investment costs. It is based on extensive studies on heat and mass transfer using 6 different condensation / heat transfer surfaces or material combinations. Basically all 6 condensation surfaces except glass are of a sheet metal or an expanded metal (to the evaporation side) in combination to an acid- and heat-resistant foil (on the salt water side). The basic experiments were performed in a "lab scale" unit to determine their thermodynamic and structural characteristics and user-friendliness. After validation in a prototype novel oxidic condensation surfaces (AF) and material combinations are in actual use in the new MSD systems, following the requirements, including a good wetting and condensation behavior and a good heat transfer.