Demonstration of a small-scale power generator using supercritical CO₂

The supercritical CO2 (sCO(2)) power cycle could improve efficiencies for a wide range of thermal power plants. The sCO(2) turbine generator plays an important role in the sCO(2) power cycle by directly converting thermal energy into mechanical work and electric power. The operation of the generator encounters challenges, including high temperature, high pressure, high rotational speed, and other engineering problems, such as leakage. Experimental studies of sCO(2) turbines are insufficient because of the significant difficulties in turbine manufacturing and system construction. Unlike most experimental investigations that primarily focus on 100 kW- or MW-scale power generation systems, we consider, for the first time, a small-scale power generator using sCO(2). A partial admission axial turbine was designed and manufactured with a rated rotational speed of 40,000 rpm, and a CO2 transcritical power cycle test loop was constructed to validate the performance of our manufactured generator. A resistant gas was proposed in the constructed turbine expander to solve the leakage issue. Both dynamic and steady performances were investigated. The results indicated that a peak electric power of 11.55 kW was achieved at 29,369 rpm. The maximum total efficiency of the turbo-generator was 58.98%, which was affected by both the turbine rotational speed and pressure ratio, according to the proposed performance map.