Session: 04-02: SMRs, Advanced Reactors and Fusion

Paper Number: 133224

133224 - Analytical Study of Matching of Dual Compressor Modules With Turbine for Small Modular Reactors 

Abstract: 

The gasdynamics performance of a 44 MWe helium axial turbomachine for a nuclear power plant is studied. Helium enters the compressor at a nominal design condition of 69.4 kg/s, with nominal total pressure and temperature of 3.25 MPa and 316.15 K respectively.  The nominal compressor reference speed is 1194 rad/s (11,400 rpm).  A standard repeating-row, repeating-stage, mean-line approach was adopted for the compressor analysis.  A loss model assuming a constant compressor polytropic efficiency, and constant rotor/stator loss terms was used.  The results were expressed in terms of the incident flow angle and Mach number of the first stage of the stage pressure ratio, rotor mean radius and rotor tip speed for three hub-to-tip radii of 0.7, 0.8 and 0.9 and the degree of reaction.  Stage and overall performance parameters were computed.  A total of 14 stages was needed to achieve the design requirements.  The design splitted the 14 stages into two “modules” of 7 stages (low- and high-pressure modules) each with an intercooler in between, with the objective of improving performance.  The intercooler was designed to reduce the total temperature to 316.15 K of the helium entering the high-pressure module.  The exit total pressure of the helium is specified to be 4.78 MPa, depending on the performance of the low-pressure module, as a constraint in the design.  The nominal length of the compressor is 0.84 m.

The turbine entrance requirements are a nominal mass flux of 65.9 kg/s.  Nominal turbine inlet total pressure and total temperature are 7.0 MPa and 800 deg C respectively. Nominal turbine exit total pressure and total temperature are 3.3 MPa and 540 deg C respectively.  The turbine analysis followed a similar repeating-row, repeating-stage, mean-line approach as for the compressor.  The first turbine stage required a different treatment because the incoming flow is not inclined to the axial direction.  Aungier’s [Turbine Aerodynamics: Axial-Flow and Radial-Inflow Turbine Design and Analysis, ASME Press, New York, 2005] loss model was used to estimate the total pressure losses.  The output was presented in terms of the rotor relative flow angle of 0.60, 0.70 and 0.80, parameterized by the inlet Mach number, the degree of reaction.  The outputs included the adiabatic efficiency and turbine exit total pressure, or any other parameter of interest, for individual stages and the overall turbine.  Six stages were required to drive the compressor and deliver the 44 MWe for a nominal total output of 100 MWt.  The nominal dimensions of the turbine are a diameter of 0.753 m and a length of 0.7 m.

Compressor and turbine operating maps were generated consisting of adiabatic efficiency and compressor pressure ratio (or the inverse of the turbine pressure ratio) versus corrected mass flow for different corrected rpm.  For the compressor, two sets of maps were generated, the single compressor and the two-module concept.  The two-module design showed a performance increase.  Further, these maps showed that the low-pressure module’s operating line was close to the surge line.  It is suggested that a bleed of 10 – 30 percent would move the operating line further from the surge line.  There is no need to apply bleed to the high-pressure module.

The full paper will provide details of the compressor and turbine analysis, the matching procedure and a critical evaluation of the dual-module design.

Presenting Author: Frank Lu Univ Of Texas At Arlington

Presenting Author Biography: Frank Lu is a professor of mechanical and aerospace engineering. His primary interests are aerospace propulsion, power production, energy conversion, aerodynamics and gasdynamics.

Authors:

Frank Lu Univ Of Texas At Arlington
Ananthkumar Jayamani University of Texas at Arlington
Daejong Kim University of Texas at Arlington
John Bolin General Atomics
Radu Curiac General Atomics
Hangbok Choi General Atomics