Investigation on laminar burning velocity measurements of premixed Ethane-Air mixture at higher pressure and temperature conditions

The externally heated diverging channel (EHDC) method was utilized to evaluate the laminar burning velocity (LBV) of premixed ethane-air flames at higher mixture temperature (350-620 K) and pressure (1-5 atm) conditions over different mixture strengths (phi = 0.7-1.3). The maximum LBV was noted at phi = 1.1 for all pressure and temperature conditions. The inverted parabolic behavior of the temperature exponent was obtained with the minima at phi = 1.1. The pressure exponent (beta) exhibits a parabolic variation with its maxima at phi = 1.0. The current results are further analyzed and compared with the literature measurements, and the comprehensive kinetic model predictions of USC mech II, San Diego mech, and Aramco mech 1.3. The present LBV measurements match well with the kinetic model predictions of Aramco mech 1.3 at most of the mixture and pressure conditions. The present results propose the variation of pressure exponent (beta) as a function of temperature ratio, and temperature exponent (alpha) as a function of pressure ratio for different mixture conditions (phi). A revised power-law correlation for alpha and beta variations is also recommended as, Su=Su0Tu/Tu0 proportional to 0+proportional to 11-Pu/Pu0)Pu/Pu0 beta 0+beta 11-Tu/Tu0. The sensitivity analysis indicates the maximum decrement in the positive sensitivity for the chain branching reaction HCO + M <-> H + CO + M (R30) across all the stated mixture conditions, owing to an increment in the third body effects along with pressure and temperature. The reaction pathway analysis reveals a maximum net reduction in the elemental flux (similar to 56 %) for the reaction between the species carbon monoxide (CO) and carbon dioxide (CO2) through different reactions, due to a rise in pressure and temperature

Automated summary

The externally heated diverging channel (EHDC) method was used to evaluate the laminar burning velocity (LBV) of premixed ethane-air flames under higher temperature and pressure conditions. The study found that the maximum LBV occurred at a mixture strength of 1.1 for all pressure and temperature conditions. The results were compared with literature measurements and kinetic model predictions, and it was found that the LBV measurements matched well with the predictions of the Aramco mech 1.3 model. The study also proposed variations of the pressure exponent (beta) and temperature exponent (alpha) as a function of temperature and pressure ratios, and recommended a revised power-law correlation for these variations. Sensitivity analysis showed a decrease in sensitivity for the chain branching reaction HCO + M <-> H + CO + M (R30) under all mixture conditions, due to increased third body effects, pressure, and temperature. Reaction pathway analysis revealed a significant reduction in the elemental flux for the reaction between carbon monoxide (CO) and carbon dioxide (CO2) under increased pressure and temperature.