Modeling a Turbine with TRACE Nuclear Engineering 470 Modeling a Turbine with TRACE

TURBINE A turbine is a device designed to convert internal energy of a gas to kinetic energy of rotation of a blade-generator system. All major reactor systems codes have turbine models. They are not widely used because they are unreliable. The model in TRACE is fairly new. To the extent it has been tested it appears to be superior to other models (TRAC-P, TRAC-B, and RELAP5). The current model in TRACE uses a non-conservative form of the energy equation. Can have energy conservation problems due to large pressure drops across the face representing the turbine.

TURBINE 2 Types of Turbines Reaction Turbine Impulse Turbine Multiple Stages Subsonic Flow Expansion of gas in rotor blades Impulse Turbine Single Stage (in general) Supersonic flow in nozzles No expansion of gas in the rotor blades

TURBINE The input for the TURB component is the same as the TEE with additional input to simulate a steam turbine The flow through the turbine is not treated in detail, momentum and energy convected across cell edged 2 are calculated using a lumped momentum and energy balance for the turbine.

TURBINE Turbine efficiency is delivered shaft power as a fraction of available gas kinetic energy after expansion. This can be misleading since it is not a fraction of the internal enthalpy flow. When the details of the turbine mechanical power output is not important: Model an Impulse Turbine with a choked nozzle. Model a Reaction Turbine with an area change and loss coefficients. When necessary, model the fluid temperature change across the turbine indirectly through control blocks (control break temp with a control block). You can induce a temperature change with a negative direct heat to the fluid driven by the control system (no break).