Design and modeling of vertical tube evaporator in a thermal-driven multiple effect distillation system

Abstract

Abstract The scarcity of freshwater is one of the biggest issues in the world, as a result of which more attention is given to the thermal distillation process for seawater and as well as brackish water distillation which removes almost all types of contaminants. Multiple effect distillation makes the process economical by recycling the latent heat of vaporization. In this paper a vertical tube evaporator is designed for a small scale thermal driven MED system comprising six effects and one condenser and a boiler that can produce 20–25 kg/hr of steam. VTE dimensions are calculated by estimating the outside diameter for different configurations. Heat transfer coefficient was estimated by using the developed correlations of the Bell method, Kandlikar and Kutateladze, compared with previous experiments and then used for calculating the heat transfer area for different distillate flow rates. An appropriate vertical tube evaporator is designed with the developed model to condense 25–30 kg/hr steam for producing 50–75 lt/hr freshwater. The result shows good agreement with previous work and reliability in design. The Developed model can also be used to design the vertical tube evaporator for different sizes (micro scale to large scale) MED plant.