Fuel Heat Gain and Release in Bomb Autoignition

NET interchange of heat between injected fuels and the atmospheres into which they were injected has been studied in a constant-volume combustion-bomb. These studies were undertaken to gain more information on the factors that govern the heating of injected fuels and the release of chemical energy in the autoignition process.

The data show that chemical heat release occurs only after an appreciable interval of time during which the fuel is heated and may be partly or wholly vaporized. The rapidity of this heating — and associated ignition delay — are influenced markedly by the physical properties of the surrounding gas. Fuel volatility and chemical structure have relatively little influence on the rate of heat transfer to the fuel in the pre-reaction period. It is also shown that the delay period before release of chemical energy and the rate of chemical energy release are influenced both by the chemical composition of the fuels and by gas-to-fuel heat-transfer rates during the pre-reaction period.