Performance Test Results of a Supercritical CO sub(2) Compressor Used in a New Gas Turbine Generating System

Supercritical carbon dioxide (S-CO sub(2)) gas turbines can generate power at high cycle thermal efficiency, even at modest temperatures of 500-550 degree C, because of the markedly reduced compressor work near the critical point. Furthermore, the reaction between Na and CO sub(2) is milder than that between H sub(2)O and Na. A more reliable and economically advantageous power generation system could be achieved by coupling with a sodium-cooled fast reactor. At Tokyo Institute of Technology, numerous development projects have been conducted for development of this system in cooperation with JAEA. Supercritical CO sub(2) compressor performance test results were obtained as described herein. Maximum design conditions of the supercritical CO sub(2) test apparatus are 11 MPa pressure, 150 degree C temperature, a 6 kg/s flow rate, and a rotation rate of 24,000 rpm. Different compressor design points are examined using impellers of three kinds. Then test data were obtained under steady-state conditions. The pressure ratio (compressor outlet pressure/inlet pressure) was obtained with the function of compressor rotation speed and the fluid flow rate. The data, reported herein for the first time, cover a broad region from sub-critical to supercritical pressures. No unstable phenomenon was observed in the area where the CO sub(2) properties change sharply. Results show that enthalpy rise needed to achieve the same pressure ratio near the critical point is smaller than in a sub-critical condition. Compressor test data were calculated using three-dimensional CFD code (CFX). Data of the pressure ratio vs. flow rate agreed with those implied by the fundamental compressor theory.