Abstract
LONDON Royal Society, November 21. A. R. UBBELOHDE, J. W. DRINKWATER and A. EGERTON: ‘Pro-knocks' and hydrocarbon combustion. Former arrangements for sampling the gases from the engine cylinder have been so modified that the samples can be taken when ignition is made to occur every alternate cycle either in the firing or non-firing strokes. Aldehydes are formed at the end of the compression stroke in the non-fired cycle, but the concentration is much smaller than in the firing stroke. The quantities of formaldehyde and of total aldehydes have been measured when running on various fuels; the amounts produced are insufficient to account for ‘knock’; for this, another source of peroxides is therefore needed. Experiments are described which suggest that most hydrocarbon fuels can be made to ‘knock’, provided molecules which can disrupt and give rise to a branched chain reaction are. produced or made available. The main source of the nitrogen peroxide found in the previous experiments is probably the hot active surface of the exhaust valve, and is proved not to be the flame. D. T. A. TOWNEND and E. A. C. CHAMBERLAIN: The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures. (4) Methane, ethane and propane-air mixtures. Whereas with the higher paraffins previously reported on, the ignition points were found to lie in two well-defined temperature ranges, location in the higher range occurring at low pressures, and in the lower range at higher pressures, with methane or the intermediate products to which it gives rise, they were confined to an upper range even at pressures up to 30 atmospheres. The view previously put forward that ignition in the lower system occurs when temperature and pressure conditions favour the survival and further oxidation of aldehydes (mainly acet-aldehydes) has found further support.
Article PDF
Rights and permissions
About this article
Cite this article
Societies and Academies. Nature 136, 882–883 (1935). https://doi.org/10.1038/136882b0
Published:
Issue Date:
DOI: https://doi.org/10.1038/136882b0