Abstract
Since the 1960s, the idea of using supercritical carbon dioxide (s-CO2) as the working fluid in a Brayton power cycle has been entertained (Angelino, 1968). But due to technical limitations of the time, the idea did not progress forward much. Presently, due to the availability of more know-how, better technological platform, and advanced analysis tools, many believe it is time to revisit the idea of using s-CO2 as the working fluid for power generation. Among various working fluids, s-CO2 has several significant advantages over other fluids. Primarily, the attractive qualities of s-CO2 are high efficiency, much smaller turbomachinery size and plant footprint (and therefore lower capital cost), and the potential for full carbon capture. However, the realization of these benefits will depend on overcoming several technical, engineering, and materials science challenges. Even though theoretically, the concept is highly attractive and promising, there are yet major hurdles to be passed, namely, the designing, developing, and testing a reasonable size (10 MWe or higher) prototype of a s-CO2 Brayton-cycle-based power gas turbine. This paper reviews the s-CO2 Brayton cycle technologies for power generation and critically assesses the recent challenges and development status. Further, a two-dimensional in-house code was utilized to design an impeller for an s-CO2 simple recuperated Brayton cycle, generating 10-MWe power. The results were validated first with Eckardt’s design which is often referred to as a benchmark due to the most extensive measurements he performed on centrifugal compressors. Then, a centrifugal compressor was designed by the present authors for a simple recuperated cycle, and the results were reported in detail. The results show that the designed compressor has a wide operation range, making it a viable option to be employed for the commercialization purpose of a 10-MWe s-CO2 Brayton cycle.
