Enclosure-in-Chamber Setup to Achieve Near-Zero Background Concentrations for Brake Emissions Testing (SAE Paper 2020-01-1634)
Measuring brake emission continues to be a challenging non-standardized task. Extensive research is ongoing and as seen in the work in progress presented at SAE Brake Colloquium and PMP meetings. However, open items include how to achieve lower background concentration and how to design the brake enclosure. A low background concentration is essential as brake events are short and some emissions are in the range of reported background levels. Hence these emissions are difficult to distinguish from the background level. Even more critical, a high background concentration can result in a wrong particle number emissions value, either overestimated, background counted as emissions, or underestimated, background level subtracted, and low emission events no longer detected and counted. Reducing the background level to less than 100 #/cm3 appeared to be quite challenging.