Dr. Wenting Sun is currently an associate professor of Georgia Institute of Technology, School of Aerospace Engineering. He received his B.E/M.E degrees from Tsinghua University, Department of Engineering Physics in 2005 and 2007, respectively, and Ph.D degree from Princeton University, Department of Mechanical and Aerospace Engineering in 2013. His current research focuses on combustion kinetics, model reduction, plasma-assisted combustion, and laser diagnostics. He has been awarded the Bernard Lewis Fellowship from the Combustion Institute, and Distinguished Paper Award at the 33rd International Symposium on Combustion. He received the Irvin Glassman Young Investigator Award from the Eastern States Sections of the Combustion Institute in 2018; He is a 2016 Air Force Office of Scientific Research Young Investigator Program Awardee.

Abstract

Autoignition of CH₄ and H₂/CO in CO₂ and Ar Diluent at High Pressure Conditions

The directly fired supercritical carbon dioxide (sCO₂) power cycle has high efficiency while allowing nearly complete carbon dioxide (CO₂) capture. The operating condition of sCO₂ power cycle (10 MPa to 30 MPa) combustors is dramatically different from conventional gas turbine combustors. However, combustion properties, e.g., autoigntion delays, have never been reported under sCO₂ conditions. An urgent question to be answered for supercritical carbon dioxide oxy-combustion is how well existing chemical kinetic models perform as no experimental data exists at relevant conditions. In this talk, autoignition delays at sCO₂ condition are reported for CH₄/O₂/ and H₂/CO/O₂ mixtures in CO₂ and Ar diluents above their critical pressures (approximately 100 bar). Experiments reveal that a widely used kinetic model, GRI 3.0, underpredicts the ignition delay by a factor of 3 for CH₄. However, kinetic models Aramco 2.0, USC Mech II and HP-Mech are capable of predicting autoignition delays though not validated at these conditions. For H2/CO mixture, all the tested kinetic models could reasonably predict the autoigition delays at supercritical conditions. Detailed kinetic analysis is conducted. Underlying kinetic processes controlling ignition and the effect of CO₂ as diluent is revealed for different fuels.