Thermodynamic Optimization and Offdesign Performance Analysis of a Toluene Based Rankine Cycle for Waste Heat Recovery from Medium Size Gas Turbines

In the last years, accelerated consumption of fossil fuels has caused many serious environmental problems such as global warming, ozone layer destruction and atmospheric pollution. Similarly, low-temperature waste heat has been generally discharged in several industrial processes, and it contributes to thermal pollution and environmental problem, too. Additionally, many industrial applications are characterized by the availability of low enthalpy thermal source, where the conventional systems for the conversion of thermal energy into electrical energy, based on a Rankine water cycle, work with several difficulties. The Organic Rankine Cycle should be a promising process for conversion of heat at low and medium temperature whenever the conventional water cycle has troubles. Using an organic working fluid instead of water, the ORC system works like the bottom cycle of a conventional steam power plant. This kind of cycle allows a high utilization of the available thermal source. Moreover, the choice of the working fluid is critical, because it should response to several environment claims and not only to thermophysical properties. In this paper, the results for the simulations of an Organic Rankine Cycle based on gas turbine with a diathermic oil circuit is shown. The selected working fluid is the Toluene. The design is performed with a sensitivity analysis of the main process parameters, the organic Rankine cycle is optimized through the variation of the main pressure of the fluid at different temperatures of the oil circuit. The offdesign is performed through the variation of the temperature of the air condenser