Abstract
Conversion of low-grade waste heat to electrical energy paves the way to reducing environmental pollution. This work focuses on the experimental study of an organic Rankine cycle (ORC) with an n-hexane working fluid and radial turbine expander. The heat source is varied from 120 to 190 °C with a mass flow rate of 0.10 to 0.50 kg/s and pressure between 12 and 15 bar. The heat-source temperature has a direct impact on turbine performance. Increase in the mass flow rate of the working fluid led to an increase in pressure and temperature at the turbine inlet. The rise in turbine speed enhanced electrical efficiency while cutting down isentropic efficiency. The optimum speed of the turbine increased with increasing in turbine inlet temperature. Superheating leads to an increase in power along with a decrease in isentropic efficiency. The thermal efficiency followed an increasing trend when there was an increase in turbine inlet temperature and mass flow rate and decreased with an increase in turbine speed. The electrical efficiency increased for all three cases. The system was found to have a highest thermal efficiency of 5.57% with a power of 1.75 kW. Based on the experimental results, it can be concluded that an ORC with n-hexane as the working fluid and a radial turbine as the expander can be used in low-temperature waste heat recovery systems to produce power.
Highlights
Renewable energy has immense importance in the energy sector as fossil fuels are vanishing from the Earth due to rapid industrial development
Appropriate time is left for the working fluid to get heated to a saturated state, and the turbine inlet valve is opened steadily
We found that the isentropic velocity ratio increased from 52.35 to decreased afteris a certain to the thatrpm, less time is given to isentropic the workingefficiency fluid to expand the turbine speed variedspeed, from due
Summary
Renewable energy has immense importance in the energy sector as fossil fuels are vanishing from the Earth due to rapid industrial development. Researchers are focused towards the development of alternative energy resources which can reduce dependence on nonrenewable resources. Energy consumption has increased many fold predominantly due to the progress in science and technology with a growing human population. Waste heat from automobiles, industrial processes, and greenhouse gases are released into the atmosphere, which accelerates the degree of global warming. From this perspective, waste heat needs to be used effectively to produce power, which diminishes emissions and leads to the preservation of fossil fuels
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