Modeling Over-Snow Vehicle (OSV) Fuel Use and Emissions Rates Versus Engine Load based on Real-World Measurements

摘要

Field measurements were conducted at Yellowstone National Park for a Ford E350 snow coach equipped with snow tracks that operated over a 32 mile snow covered route. Second-by-second speed, acceleration, road grade, fuel use, and emission rates were estimated based on field measurements. A physically-based model for the relationship between vehicle activity and fuel use rate was posited based on adapting the concept of Vehicle Specific Power (VSP) for highway vehicles to over-snow vehicles (OSVs). The adapted form of VSP is referred to here as an engine load parameter for OSVs (ELP_(Osv)). Fuel use rate was found to be a function of a linear combination of basis functions that represent kinetic energy, potential energy, and rolling resistance. Although aerodynamic drag was found to be unimportant, rolling resistance is more important for the measured OSV operating on snow than it is for a typical passenger car operating on dry pavement. Because OSV operators avoid using the brake, there were no observations of negative values of ELP_(Osv), which differs from activity patterns of highway vehicles. Fuel was found to be a monotonic function of ELP_(Osv). Fuel-based emission rates for CO and NOx were a monotonic function of fuel use rate. Thus, the development of a fuel use and emission rate model of OSVs based on speed, acceleration, and road grade has been demonstrated. In future work, this modeling approach will be extended to additional OSVs and will be used to make predictions of cycle average fuel use and emission rates.