The energy release during detonation (or deflagration) is only equivalent to the oxidation of the fuel by atmospheric oxygen - nothing more. During
heating of the fuel in a hermetic environment, assuming you wouldn’t want any reactions occurring during heating, there won’t be any additional
energy put into the system to be released. It’s in fact the opposite, especially since such energy as heat would be almost immediately dumped due to
the high surface area and reactivity of the fuel when dispersed - it’ll ignite anyways when subjected to rapid release and a small initiating
charge; its high temperature would just aid in sensitivity but not necessarily useful energy.
For example, a well known safety concern when milling Al powder is that it can self-ignite when rapidly exposed to the atmosphere - especially when
the powder is hot after the milling process. But, if you rapidly expose the Al powder to the atmosphere when cold, and do it right above a flame
source, it’ll still self ignite with lots of energy. In this case, the Al sensitivity IS increased as to not warrant the use of a secondary ignition
source, but the energy from the combustion itself isn’t much different.
That’s primarily because the energy density of the fuel, as in the HOFs and bond energies, is so much higher than just the energy used to heat them.
That heat applied to the system is minuscule compared to the combustion of the bulk material. |