Invited 3: 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.  


Wenting Sun

Associate Professor, Georgia Institute of Technology