Abstract One of the crucial aspects to determine the performance of Organic Rankine Cycle
(ORC) is the selection of appropriate working fluids. This paper describes the simulative
performance of several organic fluid and water as working fluid of an ORC based on exergy
analysis with a heat source from waste heat recovery. The simulation was conducted by using
Engineering Equation Solver (EES). The effect of several parameters and thermodynamic
properties of working fluid was analyzed, and part of them was used as variables for the
simulation in order to determine their sensitivity to the exergy efficiency changes. The results
of this study showed that water is not appropriate to be used as working fluid at temperature
lower than 130 °C, because the expansion process falls in saturated area. It was also found that
Benzene had the highest exergy efficiency, i.e. about 10.49%, among the dry type working
fluid. The increasing turbine inlet temperature did not lead to the increase of exergy efficiency
when using organic working fluids with critical temperature near heat source temperature.
Meanwhile, exergy efficiency decreasing linearly with the increasing condenser inlet
temperature. In addition, it was found that working fluid with high latent heat of vaporization
and specific heat exert in high exergy efficiency