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DEPENDENCE OF NITRIC OXIDE EMISSIONS ON VEHICLE LOAD: RESULTS FROM THE GTRP INSTRUMENTED VEHICLE PROGRAM
Citation:
Ripberger*, C. T., R C. Shores*, AND M. O. Rodgers. DEPENDENCE OF NITRIC OXIDE EMISSIONS ON VEHICLE LOAD: RESULTS FROM THE GTRP INSTRUMENTED VEHICLE PROGRAM. Presented at 8th CRC On-Road Vehicle Emissions Workshop, San Diego, CA, 4/20-22/98.
Description:
The presentation discussed the dependence of nitric oxide (NO) emissions on vehicle load, bases on results from an instrumented-vehicle program. The accuracy and feasibility of modal emissions models depend on algorithms to allocate vehicle emissions based on a vehicle operations. These models typically have a load model component that relates vehicle operating forces to engine and/or vehicle emissions. The presentation focuses on the accuracy and uncertainties associated with prediction of NO emissions based on various vehicle loads. The data used for this study are derived from measurements on six fully instrumented vehicles that were driven through a series of fixed obstacles at various speeds and throttle positions to observe vehicle emissions over a wide range of vehicle loads. The vehicles were also operated on a series of urban routes to evaluate emissions at high-speed cruise and other steady-state modes. Results from these data indicate that a load-based model can accurately estimate NO emissions if vehicle gearing can be estimated. The presentation discusses two approaches to evaluating vehicle gearing for modeling purposes and the advantages and limitations of each.