Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
Wen G. Wang.
Code of Federal Regulations Title 40 (CFR-40) specified a formula for calculating constant Dilution Factor (DF) to account for background pollutants in Constant Volume Sampler (CVS) emissions measurement system. However, it is recognized that the DF is dynamically changing due to the CVS mechanism. Based on the continuous measurement data obtained from natural gas vehicle emissions testing, a new approach was used in this study to calculate instantaneous DF of the CVS system during the test cycle. Using the instantaneous DF improves the accuracy of mass emission measurements, especially when the exhaust pollutant concentrations were approaching that in the ambient background air. The instantaneous DF was also used to recover the emissions concentrations in the raw engine exhaust prior to being diluted. In this study, vehicle tailpipe emissions characteristics at different engine operation modes were analyzed for different natural gas engines and measures for reducing emissions were also discussed.
Fu, Jingang, "Determination and analysis of natural gas vehicle tailpipe emissions based on continuous CVS measurement" (1998). Graduate Theses, Dissertations, and Problem Reports. 914.