Promotion of high-temperature self-ignition

• Published in: Progress in energy and combustion science Vol. 18; no. 4; pp. 297 - 325
• Main Authors: Zamansky, V.M., Borisov, A.A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1992; Elsevier Science
• Subjects: Applied sciences; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Miscellaneous; Theoretical studies. Data and constants. Metering; Spontaneous combustion; Methane; Promoter; Ammonia; Kinetic model; Hydrogen; Alcohol; Combustion; Review; Carbon monoxide; Experimental study
• ISSN: 0360-1285; 1873-216X
• DOI: 10.1016/0360-1285(92)90003-J

Available information on kinetics and mechanisms of small accelerating chemical additive interaction in self-ignitable systems in the subject of this review. Experimental studies of promoted high-temperature self-ignition indicate that promoting additives are of special importance for alternative fuels which are usually less reactive than the traditional petroleum-derived energy carriers. The review paper includes three parts: The first contains data on kinetic analysis of various promoter mechanisms. Additives producing radicals upon decomposition can reduce ignition delays by several orders of magnitude in systems with non-branched chain reactions but only weakly affect branched reactions. The analysis shows that there are optimal promoters leading to maximum promoter efficiency. Analytical and numerical solutions for promoter efficiency and rate constant of the optimal promoter are presented for cases using various interaction mechanisms. The second part considers experimental results on promoted self-ignition and oxidation of hydrogen, carbon monoxide, methane, higher hydrocarbons, methanol, ethanol, ammonia, as well as systems including nitrous oxide. The best promoters for hydrocarbon and alcohol oxidation are additives which are able to increase radical concentration without disappearing during the induction period. The experimental results and kinetic model calculations are compared. Possibility of the promoter use is discussed for pyrolysis and partial oxidation acceleration. The third part considers kinetics and mechanisms of high-temperature reactions for efficient promoters (organic nitrates, organic nitrites, and difluoroamino derivatives decomposing with NF 2-radical formation). In conclusion, promoter efficiency limits and strategy for effective promoter search are discussed.