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Urea based mobile Selective Catalytic Reduction (SCR) systems typically use a pulse width modulated injector to control the amount of reductant added to the exhaust stream. Additionally, an air assist system is provided to ensure uniform distribution of the reductant in the exhaust and to prevent injector clogging. We report on the adaptation of a commercially available pulse width modulated injector for use with a urea solution and an air assist. Flow rates and flow rate reproducibility were determined at combinations of pulse width, frequency and injector pressure drop selected to span the injector operating range. After correcting for density, deviations in flowrates were determined from the published injector calibration data when using n-heptane. These deviations were not uniform across the injector map. At the combination of low pulse width and high frequency, the deviation from the published n-heptane calibration data was the greatest.

Clean snowmobile technology has been developed and applied to an existing commercially available snowmobile. The goals of this effort included reducing exhaust emissions to levels which are below the U.S Environmental Protection Agency (EPA) 2012 standard. Additionally, noise levels were to be reduced to below the noise mandates of 78 dB(A). Further, this snowmobile can operate using any blend of gasoline and ethanol from E20 to E30. All of these goals were achieved while keeping the cost affordable. Snowmobiling is, after all, a recreational sport; thus the snowmobile must remain fun to drive and cost effective to produce. The details of this design effort including performance data are discussed in this paper. Specifically, the effort to modify a commercially available snowmobile using a three cylinder, four-stroke engine is described. This snowmobile was modified to run on a range of ethanol blended fuels using a closed-loop engine control system.

Clean snowmobile technology has been developed and applied to a commercially available two cylinder, four-stroke snowmobile. The goals of this effort included reducing exhaust and noise emissions to levels below the U.S National Parks Service (NPS) Best Available Technology (BAT) standard while increasing vehicle dynamic performance with a 50 percent peak power increase over the original equipment version. Engine thermal efficiency has been increased through Late Intake Valve Closure (LIVC) valve timing modification for Miller cycle operation, while high load power was increased through the implementation of a turbocharger and variable electronic boost control. An electronic throttle was also implemented in combination with a “performance/economy” mode switch to limit speed and increase fuel efficiency per the rider's demands.