Volume and Temperature Influences on the Effectiveness of Lean Thermal Reactors

This paper describes work done to separate and further define the effects of volume and temperature on the effectiveness of exhaust thermal reactors operating at lean (18-22:1) A/F ratios. Thirty feet of stainless tubing with a volume of over 1200in³ was added to the exhaust manifold of a 4 cylinder engine. The entire assembly was insulated to serve as a constant temperature “lean reactor”. Exhaust emission and temperature measurements at various points along the “reactor” provided data on the extent of the HC and CO oxidation reactions as a function of reactor volume. Mass flow calculations were made to calculate eahaust gas residence times. The data are presented as percent HC and CO rreacted versus gas residence time in the reactor and are plotted to show the effect of reactor temperatures ranging from 1275°F to 1675°F at various inlet HC concentrations. Limited data are also presented on the effect of exhaust flow rate on mixing.