Parametric study on thermal efficiency of the helium turbine cycle with rotor cooling flow

Thermal efficiency of a HTGR plant with helium turbine has been studied parametrically. The HTGR plant includes helium compressor, helium turbine, regenerative heat exchanger, precooler and intercooler. Small part of the outlet flow from the compressor is introduced into the high-temperature turbine rotor for cooling. With turbine inlet temperature, turbine pressure expansion ratio and cooling flow rate as parameters, thermal efficiencies were calculated numerically by computer code GASTUR-III. (1) In the regenerative cycle with turbine inlet temperature 10000C, the maximum thermal efficiencies are 46.2%, 45.6% and 45.1% for cooling flow rates 0%, 0.5% and 1% respectively. (2) In the intercooling regenerative cycle with turbine inlet temperature 10000C, the values are 48.5%, 48.0% and 47.5%. (3) With increase of the cooling flow, the thermal efficiency decreases almost linearly; 1% increase of the cooling flow results in 1% reduction of the thermal efficiency. (auth.)