Development of 1 MWe Supercritical CO2 Test Loop

Recent studies have demonstrated that sCO2 in a closed-loop recompression. Brayton cycle offers equivalent or higher cycle efficiency when compared with supercritical- or superheated-steam cycles at temperatures relevant for CSP applications. With funding under the SunShot initiative, the authors are developing a high-efficiency sCO2 turbo-expander for the solar power plant duty cycle profile and novel compact heat exchangers for the sCO2 Brayton cycle. However, no test loop exists to test the turbine and heat exchangers under development. Therefore, a customized test loop is being developed at Southwest Research Institute that will accommodate the full test pressures (80 to 280 bar) and temperatures (45 to 700°C) of the proposed Brayton cycle. The paper describes the design methodology to predict the pipe flow behavior and thermal growths as well as material selection. A customized natural gas fired heater is currently being designed, since no heater like it is available currently.