THE THERMAL CHARACTERISTICS AND ECONOMIC ANALYSIS OF A SOLAR POND COUPLED LOW TEMPERATURE MULTI STAGE DESALINATION PLANT PART I: THERMAL CHARACTERISTICS

Abstract

Salt Gradient Solar Ponds (SGSP) have the potential of providing low grade energy with the advantage of an annual thermal energy storage cycle. The development of Multi-Stage Flash (MSF) distillation plants operating below 100°C allows SGSP to be considered as the heat source for these systems. In this paper, two schemes of matching the SGSP with the MSF distillation plant are presented. The first scheme is based on the assumption that the solar pond is to be used as the sole heat source for the distillation plant (i.e. all the plant's thermal energy requirements are provided by the solar pond). The second scheme considers a hybrid system (solar + fuel), where a 20,000 m2 solar pond is linked to an otherwise stand alone, fuel driven desalination plant. Both options are simulated with the same daily product water output of 1000m3/day. The thermal simulation of the MSF desalination process was predicted by using a mathematical model based on stage by stage calculations taking into account the variations in fluid properties and flow conditions. The generated simultaneous equations of the mass and energy balances were combined and arranged in a matrix form and then translated into algorithm to predict process variables such as temperature and flash evaporation rates.