On the use of hydrogen peroxide in ignition systems bioinspiration from the bombardier beetle

A novel ignition system was studied experimentally, in which small volumes of
hydrogen peroxide -of the order of pl/s- were injected at the immediate site of
ignition, during the firing of a focus discharge igniter (FDI). Initially, the new
ignition system was evaluated at an atmospheric expansion rig in the
Mechanical Engineering of Leeds University. Afterwards, experiments were
undertaken in an atmospheric testing facility with an industrial Rolls-Royce
Olympus combustion chamber using kerosene Jet-A1 as the fuel and
atmospheric air as the oxidizer. The study concentrated on the determination of
the lean ignition limits o f the kerosene-air mixture at various air mass flow rates
with and without the addition of H20 2. Notable improvements, from 6.5% to
44%, in the ignition limits of the fuel-air mixture were attainable by using only a
maximum amount o f 10.8pl/s o f H20 2 during only the ignition process. The
study suggests that these improvements are directly related to the increase in
the ignition efficiency of the ignitor, by radical enhancement through the
injection of the H20 2 plasma medium. Comparisons were made, between a fuel
atomiser that was in normal service and of the same device but washed, in
order to test the igniter’s ability to initiate combustion under poor and high fuel
spray qualities (FSQ). The results indicate an enhanced improvement in the
ignitability limits during poor air-fuel mixing quality when using the H20 2 as
described above. A biodiesel fuel was also selected to test the effect that the
new ignitor system has in a low-volatility fuel. The question of how to create the
small amounts of hydrogen peroxide that will be used for ignition was also
approached. An idea of producing the required H20 2 came by studying the
bombardier’s beetle unique mechanism which produces H20 2 for defending
itself from predators. Simulation work using Chemkin was conducted to
investigate the production o f H20 2 by passing hydrocarbon fuels through a
catalyst. When passing propane-air through a platinum/ rhodium catalyst the
simulations show that H20 2 production is possible in rates enough to supply the
proposed novel ignition system. A more specialised study in the chemistry of
the production of H20 2, from gas-turbine fuels, is suggested. A cost effective
method o f an onsite H20 2 production in small amounts would be an ideal topic
for further study.