Simulation and exergy evaluation of a MED unit based on waste heat recovery from a gas turbine unit

Integrating MED-TVC unit with gas turbine cycle (GTC) and organic Rankine cycle (ORC) can be an effective way to take advantage of the hot exhaust gas of gas turbines. In this study, a multi-product system consisting of GTC, MED-TVC, and ORC is investigated. The energy and exergy analysis is carried out and influences some design variables such as inlet air temperature of air compressor, air compressor pressure ratio, high pressure in ORC, pinch point temperature difference, the pressure of motive steam, and TVC compression ratio on the developed system are examined. Calculation shows that the developed unit can produce 39.6 MW of power and 137.3 kg/s of fresh water with a gain output ratio of 4.41 and energy efficiency of 21.5%. According to the result, precooling the air at the entrance of the air compressor and decreasing the pinch point temperature can lead to enhancement exergy and energy efficiency of GTC and the gain output ratio of MED unit, respectively. In addition, the highest exergy destruction takes place in the combustion chamber and desalination unit.