A novel design for solar integrated multi-effect distillation driven by sensible heat and alternate storage tanks

Abstract

This article presents a novel Multi-Effect Distillation (MED) system which utilizes indirect brine heating such that a medium fluid is circulated through the concentrating solar collectors and store the energy in a charging tank. Each “effect” of a MED unit is a chamber in which cool feedwater brine is sprayed onto heat exchangers, partially evaporating the brine. The vapors and heated brine serve to pass thermal energy to subsequent effects. One of the uniqueness of the design is that the heat exchanger in the first effect of the system receives a flow of hot medium fluid, such that sensible heat is passed to the incoming feedwater. The thermal storage system consists of two identical, insulated tanks, each with sufficient volume to supply the medium fluid for a full day. A dynamic mathematical model is developed and simulated with four MED stages (“effects”). The number of concentrated solar arrays are optimized to generate a peak of 2200 metric ton per day of distilled water, with indispensable total array area of 92,000 square meter. The average daily performance ratio is 2, and the average specific thermal energy consumption is 1140 kJ per kg.