Satya Ravi

Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Mechanical and Aerospace Engineering

Committee Chair

Arvind Thiruvengadam

Committee Co-Chair

V'yacheslav Akkerman

Committee Member

Marc Besch

Committee Member

Arvind Thiruvengadam


With an increasing focus on implementing low emission heavy duty (HD) vehicles in the booming freight transportation sector, engine manufacturers have started prompting studies on addressing the technical challenges of measuring these virtually near zero levels of gaseous and particulate emissions. Moreover, from a regulatory perspective, beginning 2005, the United States Environmental Protection Agency (EPA) promulgated the in-use testing program for HD diesel engines in addition to the regular compliance testing protocol. The rule mandates the engine manufacturers to measure gaseous and particulate matter emissions using a portable emissions measurement system (PEMS) during real-world driving conditions, and verify that they meet emission standards. With the tightening regulation standards, approaching a near zero limit it has become imperative to improve the measurement capabilities for application at such low limits of exhaust gas emissions concentration determination.;The objective of this study was to both quantitatively and qualitatively evaluate the PEMS to that of laboratory grade constant volume sampling (CVS) system with respect to the measurement of criteria pollutants mainly Total Hydrocarbons (THC) and oxides of nitrogen (NOx), and to investigate into using Fourier transform infrared spectroscopy (FTIR) as an alternative to PEMS instrumentation. The present study was conducted in two heavy duty engine platforms- viz., diesel and natural gas (NG), across three different route types which were widely used for freight transportation across California. The routes were chosen in a way that they would aptly represent near-dock, local and highway operations of a typical class-8 truck. The vehicles used in the study, were tested using West Virginia University's Transportable Emissions Measurement System (WVU-TEMS). The WVU-TEMS houses an entire full-scale CVS dilution tunnel and a range of laboratory-grade emission analyzer systems inside a trailer container, hauled by the chosen vehicle. Raw exhaust emissions from these vehicles were simultaneously measured using Semtech-DS (PEMS) and MKS 2030-HS FTIR.;The study revealed that, NOx emissions were higher for both diesel and natural-gas vehicles during near-dock (start -- stop) operation mainly due to low after-treatment temperatures, however compressed NG vehicle had 95% lower NOx emissions when compared to the diesel counterpart. CO and THC emissions was near zero for diesel vehicle and higher for NG. 85-88% of THC emissions from NG vehicle was methane (CH4). NOx emissions for diesel from FTIR were within 5-9% when compared to CVS system and higher when compared to PEMS instrumentation due to the difference in measurement techniques between the two instruments while the THC emissions from CNG were within 1-4% of PEMS during the test period and higher when compared to CVS due to comparatively low emission rates.