Study on Formaldehyde Generation Mechanism and Formaldehyde Reducing Items

We have sampled the exhaust emission of a M85 fueled engine and measured formaldehyde, as well as, methanol with Gas Chromatography. The measurements were divided in two steps. In the investigation step, a time-resolved sampling device was applied to study the formaldehyde exhaust pattern during the exhaust stroke, and in the evaluation step, we tested the formaldehyde reduction effectiveness of an air assisted fuel injector and a piston plus gasket assembly with smaller crevice volume.

Investigation results indicated formaldehyde generated at crevices together with wall quenching mechanisms are dominant at hot low load conditions while at hot high load and cold conditions bulk quenching assumes more importance. These results are also seen at the evaluation step, as crevice reduction is more effective than the air assisted injector at hot low load conditions and the air assisted injection is more effective at cold conditions.