Off-Design Analysis of a Small-Scale Axial Turbine in Organic Rankine Cycle

Amidst the global energy crisis and progress in clean energy, this study aims to reduce design costs and improve the adaptability of turbines in small ORC systems. It seeks to offer enhanced renewable energy utilization methods for sustainable development. This paper focuses on the performance of an impulse single-stage turbine with partial admission and analyzes it through numerical simulations using computational fluid dynamics (CFD). The study investigates critical parameters under design and off-design conditions by varying inlet total pressure and rotor speed. The results indicate that the turbine's isentropic efficiency and power output at design conditions are 64% and 4.78 kW, respectively. The power output ranges from 4.65 kW to 6.81 kW, and the isentropic efficiency ranges from 57% to 62% under off-design conditions. Both experimental and simulation results show good agreement. Furthermore, the velocity triangles under these conditions conform to those of a pure impulse turbine. These findings demonstrate that the turbine could adapt to different conditions and facilitate the design of ORC systems.