Seawater Desalination Pilot Plant: Optimal Design and Sizing of Solar Driven-Four Effect Evaporators Combined with Heat Integration Analysis

Abstract

This paper puts forward the results and methodology used for thermal analysis, sizing and design of four effects pilot scale desalination unit combined with solar thermal energy and using falling film evaporators for a production capacity of 7m3/day. The modelling equations are given at steady-state conditions and are based on mass and heat balances equations, heat transfer equations, and thermodynamic and physical properties of each stream. MATLAB programming is used for the resolution of the developed algorithm. The impact of the important parameters, such as evaporator type, tube dimensions, heating medium and top brine temperatures on the performance ratio and heat transfer rate, has been studied. Besides, this work is completed by Pinch analysis to provide the optimal Heat Exchanger Network (HEN) taking into account three different configurations and the impact of the minimum temperature difference ∆Tmin. Results show that it is beneficial to use the horizontal falling film evaporators allowing high heat transfer coefficient values ranging between 3.18 and 3.32kW/m2/K. In addition, the optimal HEN enables a 62% reduction of thermal power needed to feed seawater heating. Also, in this study, several suggestions and criteria for evaporators and HEN design and optimization have also been dealt with.