Search Results

Automobile Particulate Matter (PM) Emission regulation requires gravimetric determination of PM collected on filter media under simulated driving conditions in the laboratory traditionally in a full flow Constant Volume Sampling (CVS) dilution tunnel. There have been discussions about whether current sampling and measurement practices are sufficiently accurate in quantifying PM at the upcoming 1mg/mi PM emissions standards of CARB LEV III. Sampling technique alternative to a CVS such as a Partial Flow Dilution (PFD) system has already been developed and is acceptable for certification testing. Lower dilution ratios and higher filter face velocity (FFV) are options to load traceable amount of PM on filter in case of light duty vehicle (LDV) testing. On the other hand higher dilution ratios and lower FFV are required for heavy duty engine (HDE) testing to keep the PM loaded on filter <400μg.

The US Code of Federal Regulations (CFR) Title 40 Part 1065 and 1066 require gravimetric determination of automobile Particulate Matter (PM) collected onto filter media from the diluted exhaust. PM is traditionally collected under simulated driving conditions in a laboratory from a full flow Constant Volume Sampler (CVS) system, where the total engine exhaust is diluted by HEPA filtered air. This conventional sampling and measurement practice is facing challenges in accurately quantifying PM at the upcoming 2025-2028 CARB LEVIII 1 mg/mi PM emissions standards. On the other hand, sampling a large amount of PM emitted from large size high power engines introduces additional challenges. Applying flow weighting, adjusting the Dilution Ratio (DR) and Filter Face Velocity (FFV) are proposed options to overcome these challenges.

A 2.5-liter light-duty diesel van certified to Euro 4 emission standards was tested in a chassis dynamometer test cell, which included a modal FTIR exhaust gas analyzer with the capability of measuring 22 separate gas species. The engine was equipped with a cooled Exhaust Gas Recirculation (EGR) system, which controls the nitrogen oxide emissions (NOx) to less than the 390 mg/km limit required by Euro 4 regulations. The vehicle was tested by dynamometer with the New European Drive Cycle (NEDC) sequence, and found to exceed the 390 mg/km NOx limit. The FTIR was applied as a diagnostic tool for the engine EGR function. The FTIR monitored N₂O, NO, NO₂, and NH₃ over the NEDC test cycles. The linear-control EGR valve failed abruptly during a subsequent test, and the relative concentration of the reduced and oxidized nitrogen species showed significant changes.