This paper describes supercritical CO~2~ (s-CO~2~) cycle technologies for power generation and critically assess the recent challenges and developments. The concept of the s-CO~2~ power-cycle was first introduced in the 1960s however, because of various technical obstacles the research progressed slowly at that time. With current global environmental and energy problems, the s-CO~2~ power cycle has regained more attention because of its unique properties as a working fluid for power-cycles. Over the last decade, there has been extensive RDD&D worldwide, in particular in the USA. Much of the effort has focused on the development of sCO2 turbomachinery, particularly on the design and construction methods of heat exchangers and materials testing. In recent years, the US DOE has invested tens millions of dollars to promote the R&D of sCO~2~ cycle power generation technologies. A six-year project to design, build, and operate a 10 MWe sCO~2~ pilot plant test facility has been planned and is funded by the US DOE. R&D of sCO2 power cycles for application for nuclear, solar, fossil fuel power and low-grade heat sources are also being actively pursued in Australia, Canada, France, Germany, Netherlands, Spain, UK and more recently, China and India. These activities are mostly confined to laboratory-scale testing and computer modelling and analysis. The s-CO2 power cycle is an innovative concept for converting thermal energy to electrical energy. Achieving the full benefits will depend on overcoming number of turbomachinery, technical, thermodynamic properties, engineering and materials science challenges. Significant progress has been made in developing some components of the systems, with some small, low temperature, s-CO2 Brayton cycles (100kWe-1MWe) emerging in the commercial market and a natural gas-fired demonstration power plant using s-CO2 cycle under construction. However, the development of a unit for power rating up to 10MWe has become a great engineering challenge despite huge amount fund available for R&D to develop and realize such a unit in the last 15 years. Each s-CO~2~ power cycle requires various turbomachines and heat exchangers for compression and expansion and heating and cooling operations. Among various working fluid, s-CO~2~ has four major advantages favorable to turbomachines: (1) Relatively low and achievable critical pressure and temperature (7.3Mpa, 304.1K). (2) The high density (\~400kg/m^3^) which results in very compact turbomachinery design. (3) The low dynamic-viscosity of s-CO~2~ can reduce the overall flow resistance. (4) Compression works are largely reduced due to the low compressibility factor which can help improve the overall thermal efficiency. All these advantages make the s-CO~2~ the perfect working fluid for the next-generation high efficiency power-cycle design. However, those advantages can be realized in a 10MWe unit only after overcoming turbomachinery components design challenges on one hand and on the other hand the corresponding need to overcome technical, engineering and materials science challenges. This paper Part II will focus on the turbomachinery components design challenges.


Prospect and Challenges for Developing and Marketing a Brayton-Cycle Based Power Genset Gas-Turbine Using Supercritical CO2: Part II \u2014The Turbomachinery Components Design Challenges

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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