Application of “Sink & Source” and “Stream wise” Methods for Exergy Analysis of Two MED Desalination Systems

Abstract

Utilization of fossil fuel for supplying of requires energy of desalination systems is common. On the other hand, solar energy is one of the high-grade energies in the world that can be found specifically in hot weather places. Therefore, utilization of solar energy for operation of desalination systems will reduce greenhouse gases and is a good alternative way. Common exergy analysis method (stream wise) uses input and output exergy of streams to calculate the efficiency and exergy loss. Another exergy analysis method, named “Sink & Source", is illustrated in the present study. The Stream wise method usually computes efficiency of systems as higher than a reliable value. For example, the computed exergy efficiency of presented high capacity MED desalination system is 88.63%, while this value is estimated about 1.04% from the new method. The uselessness of the traditional method for analyzing presented low-capacity MED desalination system is also shown. For example, the computed exergy efficiency of a low-capacity desalination system was 97.51%, while a value of 42.57% was obtained from the new method. A solar field and a solar heating system are suggested for presented high capacity and low capacity MED, respectively. Furthermore, an economic analysis of afore said desalination system is presented.