Catalyst Efficiency Under Real Road Conditions

Staab, Joachim; Pfluger, Helmut; Schröter, D.; Schürmann, D.

doi:10.4271/890495

Cited by 5 publications

(1 citation statement)

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“…Staab et al used an instrumented VW Golf to collect emissions under urban, rural, and freeway road conditions (22). More recently, Kelly and Groblicki instrumented a GM Bonneville to collect on-road emissions and have performed several experiments in Southern California (17).…”

Section: Modal Emissions Researchmentioning

confidence: 99%

Modal Emissions Modeling: A Physical Approach

Barth

Norbeck

et al. 1996

Transportation Research Record: Journal of the Transportation R

115

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Mobile source emission models currently used by state and federal agencies (e.g., Environmental Protection Agency's MOBILE and California Air Resources Board's EMFAC) are often inadequate for analyzing the emissions impact of various transportation control measures, intelligent transportation systems, alternative fuel vehicles, and more sophisticated inspection/maintenance programs contained in most state air quality management plans. These emission models are based on the assumption that vehicle running exhaust emissions can be represented as integrated values for a specific driving cycle, and then later adjusted by speed correction factors. What is needed in addition to these "regional-type" mobile source models is an emissions model that considers at a more fundamental level the modal operation of a vehicle (i.e., emissions that directly relate to vehicle operating modes such as idle, steady-state cruise, various levels of acceleration/deceleration, and so forth). A new modal-emissions modeling approach that is deterministic and based on analytical functions that describe the physical phenomena associated with vehicle operation and emissions productions is presented. This model relies on highly time-resolved emissions and vehicle operation data that must be collected from a wide range of vehicles of varying emission control technologies. Current emission modeling techniques are discussed and the modeling approach and implementation plan for a new, three-year NCHRP Project entitled "Development of a Modal Emissions Model" are described.Significant improvements are needed in the ability to characterize emissions from vehicles operating in real world conditions and in the models used to generate mobile source emission inventories. Numerous studies have shown that under most on-road operating conditions actual vehicle emissions can differ dramatically from what is predicted by current mobile source emission models (1-5). Understanding of the reasons leading to this discrepancy has improved considerably in recent years, and a more systematic approach to determining mobile source emission inventories is needed. This is particularly true given the conformity requirements of the Clean Air Act Amendments of 1990 and the aggressive implementation of transportation control measures, intelligent transportation systems, alternative fuel vehicles, and more sophisticated inspection maintenance programs contained in most state air quality management plans. Using current methods, the uncertainty of mobile source emission inventories is several factors greater than the impact of most mobile source control strategies.Numerous reasons exist for the present discrepancy between calculated and actual emission inventories: poor mathematical representation of emission control system performance as a continuous function of accumulated mileage or speed; inadequate representation of the active fleet; dated representations of driving patterns and vehicle activities; inadequate treatment of modern closed-loop emission control technology; ...

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Section: Modal Emissions Researchmentioning

confidence: 99%