Dynamic response of the supercritical C0₂ Brayton recompression cycle to various system transients
Name
547500536-MIT.pdf
Description
Full printable version
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26.3 MB
Format
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Checksum (MD5)
8b464423d8be20fdd53033a4aa7d8bd0
Author(s)
Trinh, Tri Q. (Tri Quang)
Advisor(s)
Pavel Hejzlar and Michael Driscoll.
Date Issued
2009
Publisher
Massachusetts Institute of Technology
Abstract
The supercritical carbon dioxide (SC0₂) power conversion system has been suggested for use with many of the Generation IV nuclear reactors. The SC0₂ cycle is highly attractive because of its low operating temperatures and high efficiency associated with working near the critical point of CO2. Unfortunately, the appealing features of using C0₂ near its critical point create complications in control. The Transient SC0₂ Cycles Code (TSCYCO) has been developed as a transient simulation control design and cycle scoping code for the recompression SC0₂ Brayton cycle. It is based off of the SC0₂ Power Systems (SCPS) code, and incorporates many improvements and modifications. Written in FORTRAN 90, TSCYCO uses a lumped parameter model and a momentum integral model approach. The code uses a semi-implicit solution process and implements Gaussian elimination to solve the system of equations. Transient behavior of the printed circuit heat exchangers is determined via the previously developed code HXMOD. Turbomachinery performance is modeled using the Real Gas Radial Compressor (RGRC) code with a scaling scheme for off-design conditions. Currently, TSCYCO has the capability of modeling several transients, including: loss of external load (LOEL), power load change, and cycle low-temperature change. Simulations show that TSCYCO can be run at quasi-steady state for an indefinite period of time. In the case of a 10% LOEL, the axial turbine experiences choke as a result of shaft overspeed. Turbine choke can be avoided if one bypasses more flow during LOEL.
(cont.) Moreover, one can incorporate more accurate axial turbine performance models to account for shaft speed variation. TSCYCO experiences instabilities when operated too closely to the critical point of C0₂. This could be remedied with a more robust Runge-Kutta solution method.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.
Page 208 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 159-160).
Subjects
Nuclear Science and Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
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