Study on the twin-pilot-injection strategies for the reduction in the exhaust emissions in a low-compression-ratio engine

Suh, Hyun Kyu

doi:10.1177/0954407013511072

Cited by 16 publications

(21 citation statements)

References 23 publications

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“…Previous researches have suggested that effects of injection rates and their shape on air-fuel mixing and combustion processes are significantly important to organising diesel combustion [12,13]. Suh [13] has conducted experiments on a high speed direct injection (HSDI) diesel engine for which compression ratio is 15.3 : 1 reduced from 17.8 : 1 by modification of combustion chamber shape to investigate the effects of the twin-pilot-injection strategies on combustion performance and exhaust emissions. The study shows lower NOx emissions (up to 45.7% were observed), whereas soot generation level was almost unaltered in the multiple-injection case.…”

Section: Introductionmentioning

confidence: 99%

Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

Bai¹,

Zhang²,

Du³

et al. 2017

Journal of Combustion

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When multi-injection is implemented in diesel engine via high pressure common rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are the same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid, and wedge) of injection rate profiles were investigated. Modeling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline, rectangle (flat), shape of injection rate can have better balance between NOx and soot emissions than the other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces the highest soot emissions among the five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions were produced by triangle shape due to higher peak injection rate.

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Section: Introductionmentioning

confidence: 99%

Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

Bai¹,

Zhang²,

Du³

et al. 2017

Journal of Combustion

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“…Thereafter, the piston starts compressing the trapped air inside the cylinder while moving from BDC to top dead center (TDC). When the piston reaches a few crank angle degrees before TDC, the intake valve opens again (Figure 1(a)) and the hot compressed air inside the cylinder gets ejected at high velocities back into the intake air plenum (3). During this ejection process, the first portion of air coming out of the cylinder will be at the maximum temperature attained after compression.…”

Section: Conceptualization and Implementationmentioning

confidence: 99%

“…Since emission legislations are getting stringent, lower CRs are currently being preferred in diesel engines to achieve low NO x and soot emission levels. [1][2][3] Engine downsizing with high level of turbocharging is being used worldwide to meet the CO 2 emission regulation. So, it is necessary to reduce the CR in such highly boosted engines to limit the peak firing pressure, and hence there is an interest in automotive industry in exploring the benefits of low CR diesel engines.…”

Section: Introductionmentioning

confidence: 99%

A novel method to improve the cold starting ability of a low compression ratio diesel engine through recompression of the charge

Vivegananth

Ramesh

2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Reducing the compression ratio in a diesel engine will result in lower NOx and soot emissions but will lead to problem of starting and combustion instability at cold conditions. In this work, a novel method for improving cold starting ability has been conceptualized and verified through simulations and experiments. In this method, the temperature of the charge is enhanced by ejecting the hot air into the intake manifold at the end of compression stroke. Due to the irreversibility associated with this process, the temperature of the air in the intake manifold increases and this air is again inducted into the cylinder and compressed to further augment the temperature. This cycle is repeated till the temperature at the end of compression is sufficient to autoignite the injected fuel to aid first firing. This methodology was demonstrated on a single cylinder common rail diesel engine with a compression ratio of 14:1, which indicated that the temperature in the intake manifold progressively increased by up to 75 K within 10 crank shaft rotations during cranking. In subsequent experiments with the proposed system, ignition occurred right from the second rotation, whereas there is no combustion occurred in the conventional engine at ambient conditions (28°C). However, at cold condition (10°C), partial combustion was initiated only after 15 recompression rotations and does not produce any positive work output. To mitigate this, the injection schedule was further modified such that the partially burned products were retained in the cylinder without opening the valves and recompressed which autoignited the residual fuel during the subsequent compression stroke. At the end of this compression stroke, the in-cylinder temperature and pressure were high enough and hence the fuel was again injected which resulted in sustained combustion and produced an indicated mean effective pressure (IMEP) of 6 bar that could result in starting even at cold conditions (10°C). Hence, it was demonstrated that the proposed methodology with modified valve timing and injection scheduling has the potential to start the engine at low temperatures particularly with low compression ratios.

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“…The parameters of the fuel injection process significantly affect the combustion process in the cylinder, and consequently the engine power [3,4]. Every combustion engine, including CI engine is complicated as far as the adjustment is concerned.…”

Section: Introductionmentioning

confidence: 99%

Unrepeatability of the Fuel Injection and Combustion Processes in the Diesel Engine Fuelled with Renewable Fuel

Lotko¹

2020

Adv. Sci. Technol. Res. J.

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Despite the fact that more than a hundred years have passed since the first design of the compression ignition (CI) engine appeared, its optimal design has not yet been achieved. It is still the subject of constant modernisation in order to meet the new expectations of users in terms of its dynamics, economy, and, in recent months, also ecology. The most effective fulfillment of these requirements is achieved through new solutions of the fuel supply system and electronic control of injection and combustion processes. The publication includes the test results obtained on the basis of two engines. One of them is the single-cylinder CI engine AVL5402, and the other one-a threecylinder CI engine AD3.152. The first one is equipped with the Common Rail fuel supply system, electronically controlled with the selenoid injector. The second engine has a CAV distributor fuel injection pump and traditional, mechanical controlled injectors. The paper demonstrates how these two different structural systems for supplying and controlling engine parameters affect the selected indicators of the injection and combustion process. The influence of diesel fuel (DF) and rapeseed oil (RO) feeding the engine in both different injection and control systems on the unrepeatibility of the injection pressure on the maximum combustion pressures in the engine cylinder and, consequently, non-uniformity of the crankshaft rotational movement of the engine were also pointed out. The continuation of the research in this area seems to be expedient. They can be supplemented with statistical models of these phenomena. The results obtained in this way could be helpful in optimising the design of power supply systems and engine combustion chambers.

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Study on the twin-pilot-injection strategies for the reduction in the exhaust emissions in a low-compression-ratio engine

Cited by 16 publications

References 23 publications

Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

A novel method to improve the cold starting ability of a low compression ratio diesel engine through recompression of the charge

Unrepeatability of the Fuel Injection and Combustion Processes in the Diesel Engine Fuelled with Renewable Fuel

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