Abstract
A pneumatically operated rapid compression machine is used to study the conditions under which ignition will occur when air in contact with a lubricating-oil-wetted surface is adiabatically compressed. The boundaries and violence of explosion are determined from pressure measurements made during and after compression. The specific variables investigated are initial temperature, compression ratio, oil volume, and oil type. The maximum oil temperature and compression ratio investigated are 210°C and 31/1 respectively. Several concentrations of three mineral oils are considered. In order to calculate liquid-vapour equilibrium of the lubricating oils, vapour pressure-weight loss data obtained by a flame ionization method are employed in conjunction with the carbon number distribution analysis of the lubricating oil components. The calculation of oil-air equivalence ratios in the vapour phase leads to the prediction of the effect of oil concentration and of temperature on ignition hazards. The prediction is in good agreement with experimental findings and accounts for the influence of temperature on ignition. For example, it was found that ignition occurs at 120°C for compression ratio of 31/1 but will not take place until the system is heated to 160°C for a compression ratio of 18/1.
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