Fuel Injection Strategies to Improve Emissions and Efficiency of High Compression Ratio Diesel Engines

Asad, Usman; Zheng, Ming; Han, Xiaoye; Reader, Graham T.; Wang, Meiping

doi:10.4271/2008-01-2472

Cited by 50 publications

(24 citation statements)

References 27 publications

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“…However, the HTC regions dominate the combustion process and the LTC regions are more prone to approach the HTC than the flame-out conditions. LTC in diesel engines is capable of reducing oxides of nitrogen (NO x ) and soot simultaneously, which can be implemented by the heavy use of exhaust gas recirculation (EGR), or the homogeneous charge compression ignition (HCCI) type of combustion [3][4][5][6]. In an LTC scenario, the fuel ignition is suppressed until a very lean and/or EGR diluted fuel-air mixture is prevailing throughout the cylinder.…”

Section: Introductionmentioning

confidence: 99%

Tightened intake oxygen control for improving diesel low-temperature combustion

Asad

Zheng

2011

Proceedings of the Institution of Mechanical Engineers, Part D:

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The low-temperature combustion (LTC) operation in diesel engines is challenged by the higher cycle-to-cycle variation with heavy exhaust gas recirculation (EGR) and high unburnt hydrocarbon and carbon monoxide emissions. Small variations in the intake charge dilution can further decrease the combustion efficiency, which in turn escalates the successive fluctuations of the cylinder charge, adversely affecting the stability and efficiency of the LTC operation. In this work, improvements in the promptness and accuracy of combustion control as well as tightened control on the intake oxygen concentration have been combined to enhance the robustness and efficiency of the LTC operation in diesel engines. The empirical set-up consisted of a set of field programmable gate array (FPGA) modules that were coded and interlaced to execute on-the-fly combustion event modulations on either a cycle-by-cycle or within-the-same-cycle basis. The cylinder pressure traces were analysed to provide the necessary feedback for the combustion control algorithms. A methodology for estimating the indicated mean effective pressure for the current engine cycle helped to stabilize the LTC cycles. Engine dynamometer tests demonstrated that such systematic and prompt control algorithms were effective to optimize the LTC cycles for improved fuel efficiency and exhaust emissions. Moreover, a strategy for enabling load transients within narrow LTC operating corridors was implemented and shown to improve the load management of the LTC cycles. The reported techniques were in part to establish a model-based control strategy for robust diesel LTC operations.

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Section: Introductionmentioning

confidence: 99%

Tightened intake oxygen control for improving diesel low-temperature combustion

Asad

Zheng

2011

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Empirical results indicate that simultaneous ultra-low engine emissions of NOx and soot can be achieved with diesel low temperature combustion, which can be enabled by the use of high levels of EGR or with a highly premixed cylinder charge [1][2][3][4][5][6][7][8][9]. However, the high efficiency of diesel engines is usually penalized by the elevated carbon monoxide (CO) and total hydrocarbon (THC) emissions.…”

Section: Introductionmentioning

confidence: 99%

An Enabling Study of Low Temperature Combustion With Ethanol in a Diesel Engine

Gao¹,

Divekar²,

Asad³

et al. 2013

Journal of Energy Resources Technology

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An Enabling Study of Low Temperature Combustion With Etbanoi in a Diesei EnginePrevious research indicates that the low temperature combustion (LTC) is capable of producing ultra-low nitrogen oxides (NOx) and soot emissions. The LTC in diesel engines can be enabled by the use of heavy exhaust gas recirculation (FGR) at moderate engine loads. However, when operating at higher engine loads, elevated demands of both intake boost and EGR levels to ensure ultra-low emissions make engine controllability a challenging task. In this work, a multifuel combustion strategy is implemented to improve the emission performance and engine controllability at higher engine loads. The port fueling of ethanol is ignited by the direct injection of^ diesel fuel. The ethanol impacts on the engine emissions, ignition delay, heat-release shaping, and cylinder-charge cooling have been empirically analyzed with the sweeps of different ethanol-to-diesel ratios. Zerodimensional phenomenological engine cycle simulations have been conducted to supplement the empirical work. The multifuel combustion of ethanol and diesel produces lower emissions of NOx and soot while maintaining the engine efficiency. The experimental setup and study cases are described, and the potential for the application of an ethanolto-diesel multifuel system at higher loads has been proposed and discussed.

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“…To meet the current and future emission standards, the NO x and particulate matter (PM) need to be reduced simultaneously, which is hindered by the inherent NO x -PM trade-off of the conventional diesel HTC. To achieve simultaneous low NO x and low PM, previous research has shown that the combustion tempera-ture needs to be lowered together with enhanced air-fuel mixing [2][3][4]. Diesel engines operating in such a low-temperature combustion (LTC) mode tend to produce very low levels of NO x and PM which can be realized by the heavy use of exhaust gas recirculation (EGR) or the homogeneous charge compression ignition (HCCI) type of combustion.…”

Section: Introductionmentioning

confidence: 99%

“…However, the fuel efficiency of HCCI engines is often compromised by the high levels of HC and CO emissions that may drain a substantial amount of fuel energy (5-15 per cent in certain low-load cases) from the engine cycle. While the impact of the HC emissions on the efficiency of the engine is strong [3,4], the interaction of HC with the NO x during the HCCI cycles has not been previously quantified.…”

Section: Introductionmentioning

confidence: 99%

“…In comparison, conventional diesel sprays normally have only partial and momentary contacts, typically as fuel spray impingements, with the chamber wall and primarily the bowl of the piston. More seriously, unlike conventional diesel engines, where the phasing of combustion is tightly controllable via fuel injection timing modulation [1,8], the scheduling of fuel delivery in HCCI engines has lesser leverage on the exact timing of auto-ignition, which may even occur before the compression stroke completes, or before top dead centre (BTDC) [4,9]. The decoupling between the timings of fuel injection and ignition accrues with an earlier or fuller homogeneous charge [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Hydrocarbon impact on NO_x survivability during diesel low-temperature combustion cycles

Zheng

Asad

Han

et al. 2009

Proceedings of the Institution of Mechanical Engineers, Part D:

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Low-temperature combustion (LTC) cycles are inherently inclined to produce higher amounts of combustibles because the burning of a homogeneous cylinder charge that is lean and/or exhaust gas diluted is closer to the non-combustion regions (flame-out limits). However, the impact of the hydrocarbons produced during the LTC cycles on the attainment of ultra-low levels of nitrogen oxides (NO x ) is less understood, and it is unclear whether the hydrocarbon species are a precursor to the ultra-low NO x and also contribute in part to the NO x reduction. Therefore, the impact of the hydrocarbon emissions on the NO x emission of the LTC cycles has been empirically investigated on a number of common-rail diesel engine platforms of high compression ratios. The empirical studies have been conducted under independently controlled exhaust gas recirculation, intake boost, and exhaust back pressure. The survivability of NO x under the compression and combustion processes has been presented in the context of the quasi-steady exhaust NO x and the effect of the hydrocarbons on the NO x survivability has been quantified. The chemical impact of the hydrocarbon species on the NO x emission under LTC cycles has been examined with crank-angle-resolved in-cylinder sampling techniques and fast-response emission analysers. Furthermore, the ratio of nitric oxide to nitrogen dioxide under the LTC cycles has been quantified and compared with that in conventional diesel combustion. This paper intends to identify the major impacts of the hydrocarbons on the NO x emission of diesel LTC cycles.

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Fuel Injection Strategies to Improve Emissions and Efficiency of High Compression Ratio Diesel Engines

Cited by 50 publications

References 27 publications

Tightened intake oxygen control for improving diesel low-temperature combustion

Tightened intake oxygen control for improving diesel low-temperature combustion

An Enabling Study of Low Temperature Combustion With Ethanol in a Diesel Engine

Hydrocarbon impact on NO_x survivability during diesel low-temperature combustion cycles

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Fuel Injection Strategies to Improve Emissions and Efficiency of High Compression Ratio Diesel Engines

Cited by 50 publications

References 27 publications

Tightened intake oxygen control for improving diesel low-temperature combustion

Tightened intake oxygen control for improving diesel low-temperature combustion

An Enabling Study of Low Temperature Combustion With Ethanol in a Diesel Engine

Hydrocarbon impact on NOx survivability during diesel low-temperature combustion cycles

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Product

Resources

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Hydrocarbon impact on NO_x survivability during diesel low-temperature combustion cycles