Supercritical Carbon Dioxide Brayton Power Conversion Cycle Design for Optimized Battery-Type Integral Reactor System

摘要

Supercritical carbon dioxide (SCO_(2)) promises a high power conversion efficiency of the recompression Brayton cycle due to its excellent compressibility reducing the compression work at the bottom of the cycle and to a higher density than helium or steam decreasing the component size. Therefore, the high SCO_(2) Brayton cycle efficiency as high as 45 percent furnishes small sized nuclear reactors with economical benefits on the plant construction and maintenance. A 23 MWth BORIS (Battery Optimized Reactor Integral System) is being developed as a multi-purpose reactor. BORIS, an integral-type optimized fast reactor with an ultra long life core, is coupled to the SCO_(2) Brayton cycle needing less room relative to the Rankine steam cycle because of its smaller components. The SCO_(2) Brayton cycle of BORIS consists of a 16 MW turbine, a 32 MW high temperature recuperator, a 14 MW low temperature recuperator, an 11 MW precooler and 2 and 2.8 MW compressors. Entering six heat exchangers between primary and secondary system at 19.9 MPa and 663 K, the SCO_(2) leaves the heat exchangers at 19.9 MPa and 823 K. The promising secondary system efficiency of 45 percent was calculated by a theoretical method in which the main parameters include pressure, temperature, heater power, the turbine's, recuperators' and compressors' efficiencies, and the flow split ratio of SCO_(2) going out from the low temperature recuperator. Test loop SOLOS (Shell-and-tube Overall Layout Optimization Study) is utilized to develop advanced techniques needed to adopt the shell-and-tube type heat exchanger in the secondary loop of BORIS by studying the SCO_(2) behavior from both thermal and hydrodynamic points of view. Concurrently, a computational fluid dynamics (CFD) code analysis is being conducted to develop an optimal analytical method of the SCO_(2) turbine efficiency having the parameters of flow characteristics of SCO_(2) passing through buckets of the turbine. These simultaneous experimental and analytical methods for designing the secondary loop of BORIS can supply an optimal solution to developing a new battery-type integral nuclear power reactor system.