Search Results

New emissions certification requirements for medium duty vehicles (MDV) meeting chassis dynamometer regulations in the 8,500 lb to 14,000 lb weight classes as well as heavy duty (HD) engine dynamometer certified applications in both the under 14,000 lb and over 14,000 lb weight classes employing large diameter exhaust pipes (up to 4″) have created new exhaust stream sampling concerns. Current On-Board-Diagnostic (OBD) dyno certified particulate matter (PM) requirements were/are 7x the standard for 2010-2012 applications with a planned phase in down to 3x the standard by 2017. Chassis certified applications undergo a similar reduction down to 1.75x the standard for 2017 model year (MY) applications. Failure detection of a Diesel Particulate Filter (DPF) at these low detection limits facilitates the need for a particulate matter sensor.

The goal of the present work was to investigate the ability of the SEMTECH®-D Portable Emissions Measurement System (PEMS) to provide simultaneous, accurate, real-time (1Hz) measurements of NO and NO2 in vehicle exhaust. Extensive chassis dynamometer laboratory evaluation studies of the SEMTECH® system were conducted. The instantaneous (1Hz) NOx emissions were measured using a conventional chemiluminescence analyzer (CLA) and were compared to the sum of the instantaneous NO and NO2 measurements from the SEMTECH®-D. The sum of the NO and NO2 emissions measured by the SEMTECH® were in excellent agreement (within 95% in most cases) with the total NOx measurements from the conventional CLA. During the laboratory evaluation studies, several Federal Test Procedure (FTP) drive cycles were conducted. Examples of the NO and NO2 concentration and mass emissions measured using the SEMTECH®-D are presented along with the corresponding SEMTECH®-D detection limits.

A commercially available Portable Emissions Measurement System (PEMS), the SEMTECH-G® (Sensors Inc., Saline, MI), was evaluated under laboratory conditions at a chassis dynamometer test facility at Ford Motor Company's Research and Innovation Center. Cumulative Mass Emissions (CMEs) for carbon monoxide (CO), total hydrocarbons (THC), oxides of nitrogen (NOx), and carbon dioxide (CO2) were measured for three different gasoline powered vehicles. A total of twenty three test cycles were conducted. Results from the conventional laboratory bag analyzer system (Horiba MEXA®7200-TR), the conventional laboratory modal analyzer system (Horiba MEXA® 7100-DEGR), and SEMTECH-G® were compared. CMEs for CO, THC, NOx, and CO2 measured using the SEMTECH-G® were found to be in good agreement (within 10% in all cases) with the results from the conventional modal analyzers.

A commercial PEMS, the SemtechD, was evaluated for its suitability to measure transient emissions from light-duty, oxidation catalyst equipped, diesel passenger cars. The PEMS was evaluated for its analytical capabilities in a state-of-the-art chassis dynamometer test facility. The system, manufactured by Sensors, Inc of Saline, MI, proved to be both accurate and precise. The SemtechD proved capable of measuring THC concentrations (FID-based measurement) as low as 2 ppmC with measurements on average within 4.5% of those reported by modal test cell instrumentation. Similarly, both CO and NOx measurements fell within 9% and 3% of the values reported (respectively) by modal test cell analyzers. Finally, modal CO2 agreed within 2.6% of the two measurement systems across eleven vehicle tests and with more than 6000 data points compared.