Effects of Trip Distance on Evaporative Hot Soak Emissions, Exhaust Emissions, and Fuel Tank Pressures and Temperatures

摘要

The Environmental Protection Agency's current computer model for determining the emissions rates of motor vehicles (MOBILE3) does not consider the effects of trip distance and elevated ambient temperatures on hot soak evaporative emissions and exhaust emissions. Additionally, the emissions of vehicles equipped with port fuel injection were expected to be more sensitive to trip distance and elevated ambient temperatures than carbureted and throttle body injected vehicles, and port injected vehicles are expanding their market share. Because these factors can significantly affect the Nation's air quality, EPA initiated a project to test these hypotheses. On-road tests were performed to determine the effects of summertime climate and trip distance on fuel tank temperatures and pressures. The project also included carbureted and throttle body fuel injected vehicles. Correction factors are recommended for trip distance and elevated ambient temperatures in future EPA computer models of motor vehicle emissions rates.