Design Study of Power Conversion System for the Gas Turbine High Temperature Reactor (GTHTR300)

A design study of the power conversion system for the Gas Turbine High Temperature Reactor (GTHTR300) was carried out. The study aimed at reducing the total mass of main system components, which simplified system configuration by selecting the non-inter-cooled cycle, and improvement of the performance of power conversion components to enhance economics. The 3-dimensional aerodynamic design of the turbine and compressor achieved high polytropic efficiencies of 93 and 90%, respectively, while reducing the differential thrust of the turbo-compressor to 10kN as well as keeping a high surge margin of 30% for the compressor, which made it possible to attain a high power conversion efficiency of 45.8%. A horizontal turbo-machine layout, in which the turbo-compressor and generator rotors were connected by a diaphragm-coupling, was proposed to lessen the load requirements for magnetic bearings. The turbo-machine rotor, which passed over critical speeds of bending mode, fulfilled the standard limit of vibration amplitude of 75μm at the rated rotational speed by optimizing the stiffness of the magnetic bearings. The main focus of the heat exchanger design was size and mass minimization, while fulfilling the target temperature efficiency of 95%. The plate-fin type recuperator employed an off-set fin arrangement, having a square cross section of 1.2mm×1.2mm. The pre-cooler employed helicalcoil tubes with low lateral fins. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan.