Opportunities for microgravity research in the development of practical catalytic combustion systems

Abstract

Catalytic combustion is an emerging technology that enables combustion of ultra-lean mixtures, leading to very low NOx emissions as a result of the low combustion temperatures. While it is now clear that combustion catalysts can be engineered into practical combustion systems, the essential surface-chemistry processes are not at all well understood. Therefore, optimal design and control is limited by a lack of fundamental understanding. In practical systems, the need for high catalyst surface area (e.g., a honeycomb monolith) obscures the surface itself from diagnostics probing and thus frustrates the collection of needed fundamental data. Laboratory-based experiments that use idealized geometries are required to probe the catalytic surfaces themselves and the adjacent gas-phase boundary layers. This paper develops a set of scaling laws that reveal how the effects of buoyancy restrict the use and interpretation of terrestrial laboratory-based experiments for the discovery of fundamental catalytic chemistr...