A design process for cryogenic expanders that supplies 0.5 TPD of liquefied hydrogen in hydrogen liquefaction plants is introduced. To improve the efficiency of the expander, the optimum design was conducted by adjusting two rotor shape parameters. The designed expander for hydrogen liquefaction has a target rotation speed of 75,000 rpm, and helium is applied as the working fluid. Since the operating temperature of the expander is as low as 49 K, a design that reflects the real gas properties must be considered. For a high-efficiency hydrogen liquefaction plant, increasing the expander efficiency is one of the most critical issues. In this study, the efficiency of the cryogenic expander was optimized using the response surface method (RSM). The hub and shroud meridional contours and blade $\beta$ angle distributions were chosen as the design parameters. As a result, through the optimized design, it was possible to improve the expander efficiency by up to 1.98% compared to the original expander. Flow analysis was conducted to investigate the reason for the efficiency improvement. Through this study, the effect of the blade meridional contour and blade $\beta$ angle on the cryogenic expander efficiency was verified.

This paper provides the performance test for start-up and self-sustaining of 500W ultra-micro gas turbine (UMGT) generator. Each component of UMGT, a centrifugal compressor, a radial turbine, an annular combustor and a shaft is already designed, manufactured and tested to meet design requirements in previous researches. However, they are not tested to work in an integrate system. Currently, integrated test unit with a compressor, a combustor and a turbine, is developed to find the proper condition of start-up and self-sustain. Ignition sequence depending on rotating speed is designed. Performance test for start-up and self-sustain is designed based on the ignition possible condition. An air impingement starter and a hot bulb inginer are applied. LPG is used as main fuel.

To improve the core technology of the micro gas turbine, the performance test facility was developed. This paper is focusing on the explanation of the characteristics of micro gas turbine and its assist devices. Major part of micro gas turbine were radial type of compressor, annular type of combustor, radial type of turbine, thrust foil bearing, radial foil bearing and generator. The assist devices were consist of exhaust duct, inverter, data acquisition system, load bank and test cell. Before building up the test facility, the component test was previously conducted to confirm the component performance. After the test facility was prepared, the motoring test was conducted to investigate the rotor dynamic characteristics of the micro gas turbine. Also, the part load performance test was performed. With a developed micro gas turbine test facility, the improved core technology about the micro gas turbine can be suggested to the related industries.