This content is not included in your SAE MOBILUS subscription, or you are not logged in.
A Method for Comparing Transient NOx Emissions With Weighted Steady State Test Results
ISSN: 0148-7191, e-ISSN: 2688-3627
Published February 23, 1998 by SAE International in United States
Annotation ability available
This paper describes a method used to compare the emissions from transient operation of an engine with the emissions from steady state operating modes of the engine. Weightings were assigned to each mode based on the transient cycle under evaluation. The method of assigning the weightings for each mode took into account several factors, including the distance between each second of the transient cycle's speed-and-torque point requests (in a speed vs. torque coordinate system) and the given mode. Two transient cycles were chosen. The transient cycles were taken from actual in-use data collected on nonroad engines during in-field operation. The steady state modes selected were based on both International Standard Organization (ISO) test modes, as well as, augmentation based on contour plots of the emissions from nonroad diesel engines. Twenty-four (24) steady-state modes were used.
The transient cycle's speed-and-torque points are used to weight each steady state mode in the method. Based on this assumption, a larger number of speed-and-torque points in the transient cycle will be located closer to those modes1 with higher weightings. The actual method used to distribute and weight the modes is termed the proportional modal weighting method. It is discussed below.
The method broached in this paper is one of many methods that may be used in the evaluation of emissions from transient and steady state engine operation. Weights are assigned based on actual in-use data. This will allow for a more representative comparison of steady-state and transient test cycles, where the steady-state modes are weighted specifically for the transient cycle with which it is being compared. This will demonstrate the adequacy of using this weighting method for a steady state characterization of transient nitrogen oxides (NOx), hydrocarbons (HCs), and particulate matter (PM) emissions from actual engine operation.
CitationSwain, D., Jackson, C., Lindhjem, C., and Hoffman, G., "A Method for Comparing Transient NOx Emissions With Weighted Steady State Test Results," SAE Technical Paper 980408, 1998, https://doi.org/10.4271/980408.
- Lindhjem, C.E., “Heavy-Duty Diesel Emissions Modeling,” Emission Inventory: Planning for the Future, Air and Waste Management Association Conference, Research Triangle Park, NC, USA, October, 28-30, 1997.
- Fleisch, T., McCarthy, C., Basu, A., Udovich, C., Charbonneau, P., Slodowske, W., Mikkelson, S-E, and McCandless, J., “A New Clean Diesel Technology: Demonstration of ULEV Emissions on a Navistar Diesel Engine Fueled with Dimethyl Ether,” SAE-950061.
- Committee of Common Market Automobile Constructors, “US Transient Cycle - A Suitable Test Method for Measuring Exhaust Emission Levels of Heavy-Duty Diesel Engines within European Context?,” VE/CCMC/40, September 19, 1990.
- Sams, T. and Tieber, J., “Emission behavior of heavy-duty vehicles: a holistic calculation method,” Int. J. Vehicle Design, v. 18, n. 3/4, pp 293-311, 1997.
- Golvert, A.A., “The Method for Development of a Diesel Engine Universal Performance Map,” SAE-941928.
- Webb Cynthia C., “Nonroad Data Analysis and Cycle Generation”, Southwest Research Institute, 08-5374-022, September, 1995.