An Investigation of the Effect of Differing Filter Face Velocities on Particulate Mass Weight from Heavy-Duty Diesel Engines

Due to continuing reductions in EPA's emission standard values for exhaust particulate emissions, industry production has shifted towards engines that produce very low amounts of particulate emissions. Thus, it is very possible that future engines will challenge the error range of the current instrumentation and procedures used to measure particulate emissions by being designed to produce extremely low levels of particulates.

When low particulate emitting engines are sampled at low flowrates, the resulting filter loadings may violate the minimum filter loading recommendation in the Heavy Duty Federal Test Procedure [1]. Conversely, higher flow rates may be an inappropriate option for increasing filter loading due to the possibility of stripping volatile organic compounds from the particulate sample or otherwise artificially reducing the accumulated mass [2]. Thus, it is necessary to determine the applicability of the current heavy duty particulate testing procedures to low particulate emission rate engines.

The primary aim of this work is to evaluate the effect of filter face velocity (FFV) on the weight of particulate collected during a standard engine emissions test. In particular, an attempt will be made to determine a flow range that will maximize filter loading but not strip volatile organic compounds from the particulate sample. Filter face velocity is varied by changing filter face area and size of filter. Engine operating conditions are varied over a wide variety of typical operating conditions. Statistical analyses will be used to describe the data and make conclusions about the effect of flow rates on the accuracy of measuring the amount of particulate matter collected as well as on optimal flow rates.