Engineering a Pressurised Wind Tunnel Aimed at Developing CO2 Turbomachinery

The number of people researching the supercritical CO2 power cycle has largely increased in the last few years. Just to mention, in contrast to the one or two technical papers in the topic submitted yearly to Turbo Expo until 2011, the number of contributions in the topic has rocketed to twenty in the last conference held in Copenhagen. Such astounding and unexpected growth has eventually given rise to the International Gas Turbine Institute creating a new dedicated technical committee. Nevertheless, in spite of the large attention captured by the SCO2 power cycle, most efforts are devoted to the adaption of existing equipment (turbomachinery and heat exchangers) rather than to analysing the particular features of this unconventional working fluid. Hence, the test plants already in operation as well as the numerous CFD analyses under development rely on the existing ideal-gas based knowledge typically used by the gas turbine industry. This is the reason why the compressors in these test plants are far from their theoretical performance (typically 65% real vs. 80% theoretical efficiency).The partnership formed by the University of Seville and Altran has engineered a first-of-a-kind wind tunnel for aerodynamic testing of carbon dioxide flows at high pressure. This unique facility incorporates special features like new seals, variable pressure operation and remote data acquisition which cannot be adapted from conventional wind tunnels. This development is expected to provide the industry with a tool to increase the efficiency of SCO2 turbomachinery by large what would eventually allow for a faster and wider deployment of the technology. The university of Seville and Altran are currently raising capital to construct the facility.Copyright © 2013 by ASME