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Technical Paper

Evaluation of Diesel Spray with Non-Circular Nozzle - Part I: Inert Spray

2019-01-15
2019-01-0065
Numerous studies have characterized the impact of high injection pressure and small nozzle holes on spray quality and the subsequent impact on combustion. Higher injection pressure or smaller nozzle diameter usually reduce soot emissions owing to better atomization quality and fuel-air mixing enhancement. The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. An alternate approach impacting spray quality is investigated in this paper, specifically the impact of non-circular nozzles. The concept was explored experimentally in an optically accessible constant-volume combustion chamber (CVCC). Non-reacting spray evaluations were conducted at various ambient densities (14.8, 22.8, 30 kg/m3) under inert gas of Nitrogen (N2) while injection pressure was kept at 100 MPa. Shadowgraph imaging was used to obtain macroscopic spray characteristics such as spray structure, spray penetration, and the spray cone angle.
Technical Paper

Effect of Micro-Hole Nozzle on Diesel Spray and Combustion

2018-04-03
2018-01-0301
The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. One area of promise, injector nozzles with micro-holes (i.e. down to 30 μm), still need further investigation. Reduction of nozzle orifice diameter and increased fuel injection pressure typically promotes air entrainment near-nozzle during start of injection. This leads to better premixing and consequently leaner combustion, hence lowering the formation of soot. Advances in numerical simulation have made it possible to study the effect of different nozzle diameters on the spray and combustion in great detail. In this study, a baseline model was developed for investigating the spray and combustion of diesel fuel at the Spray A condition (nozzle diameter of 90 μm) from the Engine Combustion Network (ECN) community.
Technical Paper

Improving Heavy Duty Natural Gas Engine Efficiency: A Systematic Approach to Application of Dedicated EGR

2020-04-14
2020-01-0818
The worldwide trend of tightening CO2 emissions standards and desire for near zero emissions is driving development of high efficiency natural gas engines for a low CO2 replacement of traditional diesel engines. A Cummins Westport ISX12 G was previously converted to a Dedicated EGR® (D-EGR®) configuration with two out of the six cylinders acting as the EGR producing cylinders. Using a systems approach, the combustion and turbocharging systems were optimized for improved efficiency while maintaining the potential for achieving 0.02 g/bhp-hr NOX standards. A prototype variable nozzle turbocharger was selected to maintain the stock torque curve. The EGR delivery method enabled a reduction in pre-turbine pressure as the turbine was not required to be undersized to drive EGR. A high energy Dual Coil Offset (DCO®) ignition system was utilized to maintain stable combustion with increased EGR rates.
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