Barometric calorimeters

A barometric calorimeter technique has been developed to characterize the temporal evolution of combustion in confined explosions. By comparing pressure measurements for explosions in air versus nitrogen, one can make visible the gasdynamic (pressure) consequences of the exothermic energy release. The late-time chamber pressure measurement is used to evaluate the final mass-fraction of products produced by combustion. Combustion completeness varied from 50–89% over a wide range of stoichiometrics. A thermodynamic model of combustion in a calorimeter is proposed. The model was applied to the TNT-air system; chamber pressures varied between 1 bar and 1 kbar for fuel mass-fractions between 1 and 99%. Chamber temperature reached a maximum of 2.099 K at a fuel mass loading of 36%. We will show that combustion is a more-effective energy release mechanism for creating high temperatures and pressures in a confined explosion than the detonation mechanism.