Development of micro-scale radial inflow turbine for organic Rankine cycle

This study describes the development of a micro-radial turbine for organic Rankine cycle powered by low temperature heat source. To achieve the aim, different working fluids with operating conditions were investigated to identify the most efficient turbine for low-grade heat source with temperature less than 85 °C. In previous studies related to organic Rankine cycle analysis, the isentropic efficiency of the turbine was assumed constant, while in this work, the isentropic efficiency is calculated at different operating conditions for each working fluid. The ANSYS^R17- CFX software is used to perform the three-dimensional computational fluid dynamic analysis of the radial-inflow turbine for a number of organic working fluids (R141b, R245fa and n-pentane) and different operating conditions. The real fluid properties using equations of state were employed and results showed that n-pentane has the highest performance for all operating conditions. The maximum total isentropic efficiency of turbine was about 80.15% with 5.119 kW power output and 10.34% cycle thermal efficiency.