Multi-Variable Sensitivity Analysis and Ranking of Control Factors Impact in a Stoichiometric Micro-Pilot Natural Gas Engine at Medium Loads

Vinhaes, Vinicius Bonfochi; Yang, Xuebin; McTaggart-Cowan, Gordon; Eggart, Brian; Munshi, S. R.; Shahbakhti, Mahdi; Naber, Jeffrey

doi:10.4271/2022-01-0463

Cited by 3 publications

(1 citation statement)

References 25 publications

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“…The CA50 variance of the micro-pilot mode is larger than that of diesel-only, indicating that the micro combustion is similar to that seen in spark-ignited engines as seen in the cycle-to-cycle variation study by Sztenderowicz and Heywood. 25 A design of experiments study performed in the same micro-pilot engine operating at medium load to quantify the performance sensitivity of combustion control factors is reported in Bonfochi Vinhaes et al 26 The results have shown that, among the factors investigated (including MAP, EGR, pilot injection timing, pilot injection pressure, pilot injection duration, intake temperature, and equivalence ratio), EGR and pilot injection timing are the most influential performance control parameters. In contrast, intake temperature and pilot injection pressure were observed to have the least impact on this operating regime.…”

Section: Overview Of the Micro-pilot Diesel Natural Gas Enginementioning

confidence: 99%

Development of a medium-duty stoichiometric diesel micro-pilot natural gas engine

Vinhaes

Yang

McTaggart-Cowan

et al. 2022

International Journal of Engine Research

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Fueling a compression-ignition engine with premixed natural gas offers the potential to combine a clean-burning, low-carbon fuel with a high compression ratio, high-efficiency engine. This work describes the development of a multi-cylinder 6.7 L diesel engine converted to run stoichiometric diesel micro-pilot/ natural gas premix combustion with a maximum diesel contribution target of 5% of the total fuel energy and a three-way catalyst aftertreatment system. Results are given by comparing the stoichiometric combustion to the diesel baseline operation, showing combustion characteristics differences, including the rapid two stage heat release. A high load output of 23 bar brake mean effective pressure was obtained with diesel-like brake thermal efficiency of 41%. This operating condition enabled a brake specific CO2 emissions reduction of up to 25% when compared to diesel. It was observed that the low load output is limited by combustion stability when operated at stoichiometric condition. The three-way catalyst is observed to run at peak efficiency with an equivalence ratio of 1.01. Injector fouling was observed through the inspection of the nozzle and its internal parts, indicating carbon build-up similar to that seen in injector coking mechanisms. A comparison of the developed engine to other engine technologies is given, showing that the diesel micro-pilot natural gas engine performance is in good standing among other diesel and gas engines in the market.

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Section: Overview Of the Micro-pilot Diesel Natural Gas Enginementioning

confidence: 99%

Development of a medium-duty stoichiometric diesel micro-pilot natural gas engine

Vinhaes

Yang

McTaggart-Cowan

et al. 2022

International Journal of Engine Research

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Exergy based model predictive control of an integrated dual fuel engine and a waste heat recovery system

Reddy

Vinhaes

Naber

et al. 2023

Control Engineering Practice

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Experimental Studies of Low-Load Limit in a Stoichiometric Micro-Pilot Diesel Natural Gas Engine

Vinhaes

McTaggart-Cowan

Munshi³

et al. 2022

Energies

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While operating at light loads, diesel pilot-ignited natural gas engines with lean premixed natural gas suffer from poor combustion efficiency and high methane emissions. This work investigates the limits of low-load operation for a micro-pilot diesel natural gas engine that uses a stoichiometric mixture to enable methane and nitrogen oxide emission control. By optimizing engine hardware, operating conditions, and injection strategies, this study focused on defining the lowest achievable load while maintaining a stoichiometric equivalence ratio and with acceptable combustion stability. A multi-cylinder diesel 6.7 L engine was converted to run natural gas premix with a maximum diesel micro-pilot contribution of 10%. With a base diesel compression ratio of 17.3:1, the intake manifold pressure limit was 80 kPa(absolute). At a reduced compression ratio of 15:1, this limit increased to 85 kPa, raising the minimum stable load. Retarding the combustion phasing, typically used in spark-ignition engines to achieve lower loads, was also tested but found to be limited by degraded diesel ignition at later timings. Reducing the pilot injection pressure improved combustion stability, as did increasing pilot quantity at the cost of lower substitution ratios. The lean operation further reduced load but increased NOx and hydrocarbon emissions. At loads below the practical dual-fuel limit, a transition to lean diesel operation will likely be required with corresponding implications for the aftertreatment system.

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Multi-Variable Sensitivity Analysis and Ranking of Control Factors Impact in a Stoichiometric Micro-Pilot Natural Gas Engine at Medium Loads

Cited by 3 publications

References 25 publications

Development of a medium-duty stoichiometric diesel micro-pilot natural gas engine

Development of a medium-duty stoichiometric diesel micro-pilot natural gas engine

Exergy based model predictive control of an integrated dual fuel engine and a waste heat recovery system

Experimental Studies of Low-Load Limit in a Stoichiometric Micro-Pilot Diesel Natural Gas Engine

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