Operation of a homogeneous exhaust manifold reactor

Abstract

The thermal exhaust manifold reactor, used to reduce carbon base emissions in the exhaust of an Otto cycle engine, is a thermally insulated chamber replacing the exhaust manifold on the engine; when fresh air is added upstream of the reactor, homogeneous reactions can oxidize the emissions. The objective of the present work was to systematically investigate reactor operation in order to provide meaningful information for future reactor designs. The unique approach of simulating the spark ignition engine exhaust using a steady flow hot gas generator is implemented to eliminate the effects of the engine operation parameters. The main criterion for reactor design is its effectiveness in promoting self ignition of the mixture of engine exhaust and secondary air. It is demonstrated experimentally that the ignition is thermal in nature, which amplifies the importance of heat loss from and flow patterns within the reactor, and the optimum gas composition for promoting ignition is given. Furthermore, a correlation of these data, in terms of Damköhler's first similarity group, demonstrates the mechanism of stable and efficient reactor operation and establishes the principles of effective fluid mechanic design.