Design of a Catalytic Nitrous Oxide Decomposition Reactor

In an SBIR Phase I project for AFRL, Reaction Systems completed the conceptual design of a scramjet missile ignition system using stored nitrous oxide for fuel atomization barbotage gas and/or a pilot ignition torch. Exothermically decomposing N2O to N2 and O2 can deliver over 845 kW of thermal power per pound per second of N2O flow to aid the engine ignition process. We found that purely thermal decomposition of N2O was impractical from the standpoint of both required reactor volume and the product distribution obtained based on both computer simulations and lab experiments. We also synthesized and demonstrated highly-active, thermally-stable N2O decomposition catalysts with good low temperature activity and high selectivity for the formation of O2 and N2. Finally, we designed an N2O storage and supply system with a regeneratively-cooled N2O heat exchanger/reactor featuring a wall-mounted catalyst to minimize both pressure drop and catalyst temperature. This paper discusses our N2O storage and supply system design as well as our conceptual design of the N2O catalytic decomposition heat exchanger/reactor.