A sensitivity analysis of formation in pilot-ignited natural gas dual fuel engines is performed based on a phenomenological combustion model. The formation mechanism employed in this study incorporates a super-extended Zel’dovich mechanism (up to 43 reactions). The sensitivity analysis compares the contribution of each major reaction to formation, and identifies the rate-controlling formation reactions in different high-temperature regions—the burning pilot spray, the premixed flame associated with the gaseous fuel-air mixture, and the burned combustion products. The formation rates for reactions involving are also investigated to reveal the primary formation paths. Results show two main formation paths both in the pilot spray (also called the packets zone) and the burned zone. The rate-limiting reactions for the packets zone are and . Rate-limiting reactions for the burned zone are and . Since the aforementioned reactions significantly influence the net prediction, it is important that the corresponding reaction rates be determined accurately. Finally, because the quasi-steady-state assumption is commonly used for certain species in modeling, a transient relative error is estimated to evaluate the validity of the assumption. The relative error in prediction with and without the use of the steady-state assumption is small, of the order of 2%. This work also confirms that sensitivity analysis can provide valuable insight into the possible formation pathways in engines and improve the ability of current prediction tools to obtain more reliable predictions.
Sensitivity Analysis of Formation Kinetics in Pilot-Ignited Natural Gas Engines
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Yang, H., Krishnan, S. R., Srinivasan, K. K., and Midkiff, K. C. (May 31, 2006). "Sensitivity Analysis of Formation Kinetics in Pilot-Ignited Natural Gas Engines." ASME. J. Eng. Gas Turbines Power. January 2007; 129(1): 261–270. https://doi.org/10.1115/1.2360601
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