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Wall, J. C.
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Fuel Sulfur Reduction for Control of Diesel Particulate Emissions

Cummins Engine Company, Inc.-J. C. Wall, S. A. Shimpi, M. L. Yu
Published 1987-11-01 by SAE International in United States
The impact of diesel fuel sulfur reduction on directly-emitted and secondary atmospheric particulate is evaluated by experiment and analysis. Experimental evidence shows that fuel sulfur conversion rate to particulate sulfate is linear down to zero sulfur level.Analysis shows that sulfur-derived particulate accounts for the vast majority of atmospheric particulate from diesel engines. Consequently, fuel sulfur reduction would have a far greater impact in reducing atmospheric particulate burden than any other diesel engine particulate control strategy.
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Fuel Composition Effects on Heavy-Duty Diesel Particulate Emissions

Chevron Research Company, Fuels Division, Richmond, California-J. C. Wall, S. K. Hoekman
Published 1984-10-01 by SAE International in United States
The effects of fuel composition on diesel exhaust particulate emissions have been studied at several steady-state operating conditions using a heavy-duty laboratory engine. Particulate emissions were influenced by three primary fuel factors: sulfur content, aromatics content, and volatility. At all but lightly loaded operating conditions, fuel sulfur was the dominant fuel factor in particulate formation.Fuel sulfur affects particulate emissions primarily by formation of sulfate (as sulfuric acid) and associated “bound” water and, to a lesser degree, by increasing the amount of soluble organic material collected. Aromatics and volatility influence the amount of carbonaceous material formed.Five polynuclear aromatic hydrocarbon (PAH) compounds were measured in the soluble organic fraction. Engine operating conditions greatly affected PAH levels; however, no strong influence of fuel composition on PAH concentrations was observed in the normal range of No. 1 - No. 2 diesel fuels.
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Influence of Crankcase Lubricant Viscosity on Fuel Consumption in a Medium-Speed Diesel Engine

Chevron Research Co-J. C. Wall
Published 1982-02-01 by SAE International in United States
The influence of crankcase lubricant viscosity on brake specific fuel consumption (bsfc) has been evaluated in two medium-speed automotive diesel engines. An experimental procedure was established using steady-state operating conditions chosen to increase sensitivity of fuel consumption to changes in lubricant viscosity. The experimental procedure was used to evaluate Newtonian and non-Newtonian lubricants.Results show that, as a group, 15W-40 multigrades are slightly better in fuel economy than a SAE 30 single grade. This difference is attributed to temporary viscosity loss with the multigrades. Use of high shear stress viscosity data brings fuel consumption data with non-Newtonian lubricants into line with that of Newtonian lubricants with the same viscosity and accounts for the difference in fuel consumption observed between two multigrades blended with different molecular weight polymers of the same molecular type.A well known friction reducer shows no effect on bsfc. This confirms the predominance of viscosity in determining fuel economy in this engine.
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An Engineering Analysis of Thermal Effects in the Concentric-Cylinder High-Shear-Rate Viscometer

Chevron Research Co.-J. C. Wall
Published 1981-06-01 by SAE International in United States
Equations describing the temperature distribution and consequent change in cylinder clearance for the concentric-cylinder high-shear-rate viscometer are developed. These equations are applied to a Barber-type viscometer for experimental verification. Results demonstrate that temperature profiles and change in cylinder clearance may be accurately calculated using shear stress, angular velocity, and material constants.Parametric studies show that even in the Barber viscometer with symmetric heat flow through rotor and stator, some change in cylinder clearance is observed. Without rotor cooling, reductions in clearance of 30% or more may be observed.
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Performance and NOx Emissions Modeling of a Jet Ignition Prechamber Stratified Charge Engine

Ford Motor Company-S. D. Hires
Massachusetts Institute of Technology-A. Ekchian, John B. Heywood, R. J. Tabaczynski, J. C. Wall
Published 1976-02-01 by SAE International in United States
The development of a cycle simulation model for the jet ignition prechamber stratified charge engine is described. Given the engine geometry, load, speed, air-fuel ratios and pressures and temperatures in the two intakes, flow ratio and a suitable combustion model, the cycle simulation predicts engine indicated efficiency and NO emissions. The relative importance of the parameters required to define the combustion model are then determined, and values for ignition delay and burn angle are obtained by matching predicted and measured pressure-time curves. The variation in combustion parameters with engine operating variables is then examined. Predicted and measured NO emissions are compared, and found to be in reasonable agreement over a wide range of engine operation. The relative contribution of the prechamber NO to total exhaust NO is then examined, and in the absence of EGR, found to be the major source of NO for overall air-fuel ratios leaner than 22:1.
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The effects of age and strain rate on the mechanical properties of bone

Polytechnic-J. C. Wall, W. C. Hutton, B. M. Cryon
  • Technical Paper
  • 1974-13-0017
Published 1974-09-17 by International Research Council on Biokinetics of Impact in Switzerland
No Abstract Available.