Energy and exergy analysis of a once through multi stage flash desalination unit at variable operational temperatures

Abstract EN

This paper is to investigate the exergy and energy analysis of the once through multi stage flash (OT-MSF) desalination unit at variable operational temperatures.

Here the study is carried out theoretically by developing a computer package using visual basic 6 as a tool to encode the program.

This program contains input and output pages where many variables can be studied such as feed water, final stage and heating steam temperatures as well as heating steam and distillate mass flow rates with other variables to study the exergy and energy analysis for each stage of the unit and for the whole system as a single unit.

The performance parameters considered here are the performance ratio (PR), the exergetic efficiency and the specific heat transfer area (sA).

The results obtained have shown a clear influence of the feed water and last stage temperatures, in which the performance ratio and the exergetic efficiencies are increased by increasing feed water temperature and decreased by increasing last stage temperature.

At feed water temperature 30 o C the performance ratio obtained is 15 and the exergetic efficiency is 52 % for the OT-MSF unit.