Performance enhancement of three-stage axial turbine for Clean Organic Rankine Cycle system driven by low-temperature heat source

Abstract

High performances of Organic Rankine Cycle (ORC) system are widely used in various industrial applications. Axial flow turbine at low temperature heat source is of major importance in some processes. This work focuses on numerical analyses to improve high efficiency of a small Organic Rankine Cycle (ORC) axial turbine using n-pentane as a working fluid. Different turbine stages are proposed to ensure maximum performance for the Organic Rankine Cycle (ORC) application. In order to characterize the hydrodynamic and thermodynamic performances, 3D RANS computations are suggested for five different rotational speeds(1000 rpm, 2000 rpm, 4000 rpm, 8000 rpm, and 16,000 rpm), and four mass flow rates ranging from 0.2 to 0.5 kg/s with inlet temperature of 365 K.The results indicate that the highest turbine efficiency of 87% in the two-stage turbine with rotational speed 16,000 rpm and inlet mass flow rate 0.2 kg/s, where the mass flow rate 0.5 kg/s gives highest power output value of 10,751W.Theturbine efficiency and power output are 88.03% and 12,950 W in the steady state for three-stage turbine configuration. The transient computational process leads to the maximum values of 88% and 12,932Wforturbine efficiency and power output. These results highlight the potential of using micro-three-stage axial turbine of Organic Rankine Cycle (ORC) systems for the exchange of low temperature heat sources.