Performance evaluation of a brine-recirculation multistage flash desalination system coupled with nanofluid-based direct absorption solar collector

Abstract

A mathematical model for multistage flash (MSF) desalination system with brine recirculation (BR) configuration is developed in this study. The heat source for BR-MSF is chosen to be a nanofluid-based direct absorption solar collector (DASC) for which a numerical model is developed. Both these systems, BR-MSF and DASC are coupled via a counter-flow heat exchanger. The overall performance of the combined system is quantified in terms of gained output ratio (GOR). Moreover, the variation in GOR caused by various influencing parameters such as height (H) and length (L) of solar collector, nanoparticle volume fraction (fv) and incident flux on the collector (q) is studied in detail. The effect of these parameters on the top brine temperature (To) is also discussed. The study shows that DASC can be used as a heat source for BR-MSF system and gives high GOR ranging between 11 and 14 depending on the various operating conditions. This system is also compared with a parabolic trough collector (PTC) based BR-MSF system and it is found that DASC-based BR-MSF system gives higher GOR under identical conditions (relatively 11% higher). The exergy analysis is also presented for this system which shows the irreversibilities associated with various physical processes and components of the overall system and in addition to that exergy efficiency is also calculated for the overall system.