Thermodynamic simulatinos of rankine, trilateral and supercritical cycles for hot water and exhaust gas heat recovery

In the present study, thermodynamic performances of Rankine, trilateral and supercritical cycles are assessed. In the trilateral cycle, exergy loss is very low because of favorable temperature profile matching between the heat source and the working fluid. In the cycle simulation, operating pressures for each cycle with different working fluids are optimized so that to give highest exergy efficiency for given heat source temperature and pinch point temperature difference. Simulation results show that the exergy efficiency of trilateral cycle is about 50 %, which is about 34 % larger than that of R125 - Rankine cycle for 80°C case. For the 400°C case, water is the optimal working fluid for the trilateral cycle and the exergy efficiency is about 59.8 %. Finally, dimensionless temperature difference is introduced, and its effect on the cycle maximum available power efficiency is quantitatively assessed.