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原文传递 Evaporative Emissions from On-Road Vehicles in MOVES2014

题名：	Evaporative Emissions from On-Road Vehicles in MOVES2014
作者：	empty
关键词：	Environmental benefits##EPA Office of Transportation and Air Quality (OTAQ)##Evaporative emissions##On-road vehicles##Motor Vehicle Emission Simulator (MOVES)##Refueling emissions##Emissions assessments##Non-fuel sources##Fuel properties##Liquid fuel leaking##Fuel systems##Tank Vapor Venting (TVV)##
摘要：	EPA’s Office of Transportation and Air Quality (OTAQ) has developed the Motor Vehicle Emission Simulator (MOVES). The MOVES model estimates emissions for mobile sources covering a broad range of pollutants and allows multiple scale analysis. MOVES currently estimates emissions from cars, trucks and motorcycles. Evaporative processes can account for a significant portion of gaseous hydrocarbon emissions from gasoline vehicles. Volatile hydrocarbons evaporate from the fuel system while a vehicle is refueling, parked or driving. MOVES does not include estimates for emissions from non-fuel sources such as window washer fluid, paint, plastics, and rubber. Evaporative processes differ from exhaust emissions because they don’t directly involve combustion, which is the main process driving exhaust emissions. For this reason, evaporative emissions require a different modeling approach. In the MOBILE models and certification test procedures, evaporative emissions were quantified by the test procedures used to measure them: Running Loss -Vapor lost during vehicle operation. Hot Soak -Vapor lost after turning off a vehicle. Diurnal Cold Soak -Vapor lost while parked at ambient temperature. Refueling Loss -Vapor lost and spillage occurring during refueling. For MOVES, a new approach has been adopted to model the underlying physical processes involved in evaporation of fuels. This ”modal” approach characterizes the emissions by physical modes of generation. This mprovement in MOVES is consistent with significant changes made in MOVES2010 when, for example, the model diverged from MOBILE6 speed bins to vehicle specific power (VSP) bins. Likewise, evaporative emissions can be separated by different emissions generation processes, each having its own engineering design characteristics and failure rates. This way, certain physical processes can be isolated, for example, ethanol (EtOH) has a unique effect on permeation, which occurs in all the above modes. The approach used in MOVES categorizes evaporative emissions based on the evaporative mechanism, using the following processes: Permeation -The migration of hydrocarbons through materials in the fuel system. Tank Vapor Venting (TVV) -Vapor generated in fuel system lost to the atmosphere, when not contained by evaporative emissions control system. Liquid Leaks -Liquid fuel leaking from the fuel system, ultimately evaporating. Refueling Emissions -Spillage and vapor displacement as a result of refueling. These processes occur in each operating mode (Running Loss, Hot Soak, Cold Soak) used in the MOVES model. Each emission process can be modeled over a user-defined mix of operating modes, shown in Table 1. This makes for more accurate modeling of scenarios that do not replicate test procedures. The emission processes used by MOVES and the operating modes used for evaporative processes are shown in Table 2. Figure 1 illustrates the evaporative emission processes. Permeation occurs continuously through the tank walls, hoses, and seals. It is affected by fuel tank temperature and fuel properties. Vapor
总页数：	107
报告类型：	科技报告