Development of a 1000 W organic Rankine cycle micro-turbine-generator using polymeric structural materials and its performance test with compressed air

Highlights: • Development of a 1000 W micro-turbine for an organic Rankine cycle. • Polymeric materials used as the functional parts of the micro-turbine. • Achieved steady rotational speed of 32,000 rpm and peak speed of 40,000 rpm. • Aerodynamic efficiency predicted to be up to 0.66. -- Abstract: This paper presents the experimental advances on the implementation of structural polymeric materials in a micro-turbine-generator for an organic Rankine cycle (ORC) and through testing provides an insight of its performance. The aim is to create awareness of the huge techno-economical potential that polymers represent as metal replacement in ORC applications. A micro-turbine-generator is developed considering R245fa as the working fluid. The unit is built using polymeric components; these components include an impeller made from polyether-ether-ketone and a nozzle body made from polyethylene. A program for the simulation of the micro-turbine performance is developed, a series of tests are conducted with compressed air and the performance with R245fa is predicted. The impeller was experimentally demonstrated to be able to withstand a rotational speed of 32,040 rpm whereas the predicted results showed the aerodynamic efficiency and the aerodynamic power to be around 0.65 and 1200 W respectively. The future of polymeric materials in ORC looks promising though a long-term test using the refrigerant as the working fluid is still needed to verify material-fluid compatibility, lifespan and resistance to fatigue.