Supercritical Carbon Dioxide Advanced Brayton Cycle Design

by Henry Saari, Steen Sjolander, Kourosh Zanganeh, Bill Pearson, & Ahmed Shafeen
Carleton University
Natural Resources Canada

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The focus of this project is the design of an advanced, high-efficiency, 100 MWe closed Brayton cycle power conversion system for clean electrical power generation that uses supercritical carbon dioxide as the working fluid.

Supercritical carbon dioxide is attractive because of its low critical pressure and temperature, availability, and heat transfer and thermodynamic characteristics. One of the advantages of this cycle is the high density of the working fluid entering the compressor. This allows the compressor work to be only a fraction of the total turbine output (approximately 20 percent versus the 40 percent that is typical for an open-cycle gas turbine), resulting in a higher overall cycle efficiency. Compressor inlet conditions are near the critical point of carbon dioxide and the system is designed for a turbine inlet temperature of 750oC.  The main objectives of this project are: (1) to gain insight into the most promising cycle configurations, (2) to design the main system components (compressor, turbine, heat exchangers), and (3) to perform the overall system integration. The work involves nearly all aspects of gas turbine design, including cycle thermodynamic and performance analyses, aerodynamic and structural design, heat exchanger design, materials selection, dynamic system modelling, and control systems design. The work is done under a research and development contract with Natural Resources Canada and much of the work has been carried out by teams of undergraduate engineering students undertaking the task as a senior project that spans their entire final academic year. Students are split into a number of smaller functional groups supervised by faculty members, coordinated by a project manager and a design integration group. Several graduate, exchange, and summer students have also been involved. An overview of the results to date will be presented, with an emphasis on the cycle thermodynamic design and analysis, turbomachinery design (including compressor and turbine aerodynamics, structural, and materials considerations), heat exchanger design, and control system development.