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Abstract

A systematic study of the variation of the minimum energy for ignition of n-decane/air and 2,2,5-trimethylhexane/air mixtures, by single electrical capacitor discharges, has been made. In addition the lower limits of flammability of selected hydrocarbons have been determined, both individually and admixed, under conditions of limiting ignition energy. The lower limits of flammability determined for single and multi-component fuels has been related to the more commonly determined flash point.

An introduction (Section 1) describes the hazards associated with hydrocarbon fuels. Common methods of hazard prevention and detection are also given. The classical theories of the ignition process, expressions relating the flammable properties of fuels to their physical parameters are given, and the effects of physical conditions on the ignition of a flammable mixture are given in detail.

The experimental apparatus and procedures are described in detail (Section 2). For flammability determinations the apparatus consisted essentially of a combustion tube 120 cm. long and 5 cm. in diameter. Detection of the passage of a flame was by thermocouples.

The results obtained are presented and discussed in Section 3. It is shown that the energy required for ignition rises very rapidly as the lower limit of flammability is approached. It is also shown that under conditions of limiting ignition energy (i.e. ca. 2 J) one observes some degree of dependency of the lower limit of flammability with molecular structure. This is qualitatively correlated with the spontaneous ignition temperature and octane numbers of the fuels chosen and is quantitatively related to an alkylperoxy mechanism of oxidation.

From the lower limits of flammability of mixtures it is shown that, under the ignition conditions employed, all constituent fuels are consumed in the ignition process, i.e. Le Chatelier’s rule for the lower limits of flammability of multi-component fuels is shown to apply to the mixtures investigated.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry T Technology > TP Chemical technology
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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