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Synergy between additives in stimulating diesel-fuel ignition

Synergy between several pairs of free-radical producing additives in stimulating the ignition of fuel in a diesel engine was reported recently by Al-Rubaie et al. At a compression ratio of 17:1, it required only about two thirds as much of a 50/50 mixture of di-tert-butyl peroxide and iso-propyl nit...

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Bibliographic Details
Published in:Combustion and flame 1993-12, Vol.95 (4), p.427-429
Main Authors: Clothier, P.Q.E., Pritchard, H.O., Poirier, M.-A.
Format: Article
Language:English
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Summary:Synergy between several pairs of free-radical producing additives in stimulating the ignition of fuel in a diesel engine was reported recently by Al-Rubaie et al. At a compression ratio of 17:1, it required only about two thirds as much of a 50/50 mixture of di-tert-butyl peroxide and iso-propyl nitrate to cause the same acceleration in ignition as of either additive on its own; however, with the same fuel and a compression ratio of 13:1, the mixture was only about 10% more effective than the individual additives. They also reported that in one engine, an equal mixture of di-tert-butyl peroxide and iso-octyl nitrate (2-ethyl-hexyl nitrate) was about 25% more effective than would have been expected if they had worked independently. The authors, on the other hand (but at a lower compression ratio of 7.5:1), have found that there was no direct co-operative effect between di-tert-butyl peroxide and iso-octyl nitrate, except for a second-order one in reducing the cycle-to-cycle variability. It is clear that these synergistic effects must depend on the nature of the fuel, and upon the test conditions in the engine. Furthermore, they described several instances in which pairs of additives did not reinforce each other, but actually interfered strongly; it becomes apparent that every interaction between pairs of additives has to be considered individually. Here, they report several new examples of synergy between pairs of additives, as well as some null results. they conclude that there is no unique mechanism by which synergy arises, but they demonstrate fairly conclusively that one way is through the interaction between NO[sub 2] and CH[sub 2]O during the preignition phase.
ISSN:0010-2180
1556-2921
DOI:10.1016/0010-2180(93)90008-Q