Evaluation of the performance of an axial one-stage 10kW turbogenerator through experimental testing

Abstract

The paper describes the results of experimental research on a prototype one-stage turbo-generator with a nominal power of 10 kW and a rotational speed of 24 000 rpm. The expander at the Institute of Fluid- Flow Machinery, Polish Academy of Sciences was developed as part of the R&D project with Marani company. The unit construction consists of an overhanging rotor and shaft mounted on rolling bearings. The turbo-generator was tested on a specially constructed laboratory test stand in the first stage. Compressed air instead of refrigerant gas (R1233zd) was used. The test results converged with the parameters obtained using the RANS simulation. The convergence for the turbine mass flow was 97% of the value obtained in the CFD model, which is satisfactory. The power generated by the turbogenerator, which was compared at this stage, also achieved satisfactory convergence (95% to 97%) with the calculation model. These tests allowed determine the compliance of the adopted design assumptions and confirmed the correctness of the calculation tools used. The next stage of work was to examine the ORC unit in operating conditions. That stage was aimed at checking the correct work of the machine with the ORC system. The turbine achieved internal efficiency calculated from temperatures at a level slightly lower than that obtained from numerical calculations (total-to-static efficiency). The efficiency was equal to about 73%, and the difference between calculated and measured values do not exceed 0.25 pp. (percentage point). The electric efficiency was about 65% and a maximum electric power output of 6.8 kW was measured.