Potentials of the Miller Cycle on HD Diesel Engines Regarding Performance Increase and Reduction of Emissions

Kovacs, David; Eilts, Peter

doi:10.4271/2015-24-2440

Cited by 19 publications

(14 citation statements)

References 15 publications

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“…The comparison was performed with a constant SOI at -3 CAD ATDC and the most advanced SOIs of the optimum cases, with and without EGR. At the full load, the changes in ignition delay and the degree of premixed combustion are very marginal with different IVCs due to the relatively good ignition conditions [20]. A similar trend was observed in this study, the Miller cycle strategy slightly increased the ignition delay by lowering the initial pressure and temperature.…”

Section: /20/2015supporting

confidence: 84%

“…Kovács et al [20] investigated the Miller cycle in the upper load range of a heavy-duty diesel engine in order to reduce the peak incylinder pressure. The pressure reserve was used to combine with further measures while maintaining the maximum in-cylinder pressure of baseline case.…”

Section: /20/2015mentioning

confidence: 99%

“…It has been modified by "A higher reduction in NOx emission by 45%..." References 16,20,21,22, are incorrect in terms of formatting or missing information.…”

mentioning

confidence: 99%

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Exploring the NOx Reduction Potential of Miller Cycle and EGR on a HD Diesel Engine Operating at Full Load

Guan¹,

Pedrozo²,

Zhao³

et al. 2018

SAE Technical Paper Series

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The reduction in nitrogen oxides (NOx) emissions from heavy-duty diesel engines requires the development of more advanced combustion and control technologies to minimize the total cost of ownership (TCO), which includes both the diesel fuel consumption and the aqueous urea solution used in the selective catalytic reduction (SCR) aftertreatment system. This drives an increased need for highly efficient and clean internal combustion engines. One promising combustion strategy that can curb NOx emissions with a low fuel consumption penalty is to simultaneously reduce the in-cylinder gas temperature and pressure. This can be achieved with Miller cycle and by lowering the in-cylinder oxygen concentration via exhaust gas recirculation (EGR). The combination of Miller cycle and EGR can enable a low TCO by minimizing both the diesel fuel and urea consumptions. In this work, Miller cycle with late intake valve closing (IVC) and EGR technology were investigated on a single cylinder common rail heavy-duty diesel engine at the high load operation of 24 bar net indicated mean effective pressure. The experiments were performed with a constant intake manifold pressure of 3 bar while optimizing the start of diesel injection to keep the peak in-cylinder pressure limit of 180 bar. The aqueous urea solution consumption in the SCR aftertreatment system was estimated to evaluate the effectiveness of the strategies in terms of TCO. The calculation was based on the engine-out NOx emissions and the Euro VI NOx limit. The results revealed that the use of the Miller cycle without EGR reduced NOx emissions by 35% and the net indicated efficiency by 4% when compared to the case with the baseline IVC at-178 crank angle degrees (CAD) after top dead center (ATDC). The introduction of 8%EGR decreased the levels of NOx by 54% while maintaining similar net indicated efficiency at the baseline IVC. The combination of Miller cycle with an IVC at-127 CAD ATDC and an EGR rate of 8% achieved the best trade-off between NOx and ISFC, decreasing the NOx levels by 57% and the fuel consumption by 1.6% compared to the baseline case. Soot emissions were maintained below the Euro VI limit of 0.01 g/kW h. Carbon monoxide emissions were maintained at low levels except for the combination of an IVC at-114 and an EGR rate of 8%. Unburned hydrocarbon emissions were slightly decreased with EGR and late IVCs likely due to relatively longer ignition delays and higher exhaust gas temperature. Overall, the analysis showed that the combination of Miller cycle with an IVC at-127 CAD ATDC and 8%EGR achieved the lowest total fluid consumption despite the reduction in net indicated thermal efficiency.

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Section: /20/2015supporting

confidence: 84%

Section: /20/2015mentioning

confidence: 99%

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Exploring the NOx Reduction Potential of Miller Cycle and EGR on a HD Diesel Engine Operating at Full Load

Guan¹,

Pedrozo²,

Zhao³

et al. 2018

SAE Technical Paper Series

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show abstract

“…Besides, the VTEC system (variable valve timing and stroke) of Honda and the Nissan NVCS system of timing changes also the performance well on the engines in production [9]. Many scholars have made some contributions to the research of Miller cycle: Kovács from Braunschweig University of Technology has made a profound study on the potential of Miller cycle in diesel engines [10]; Neher from Karlsruhe University conducted an in-depth research on a naturally aspirated cogeneration lean-burn engine under an external characteristic condition [11,12]; Czech Technical University in Prague made a detailed study on Miller cycle with mixture heating as a means for the fuel economy improvement [13]; Gottschalk conducted a thorough experimental work on the knocking of the Miller cycle engine [14]. Besides, some research over valve train actuation [15] combined with high compression ratio [16] also made remarkable contributions to the valve train techniques.…”

Section: Introductionmentioning

confidence: 99%

Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load

et al. 2020

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This contribution is focused on the fuel economy improvement of the Miller cycle under part-load characteristics on a supercharged DI (Direct Injection) gasoline engine. Firstly, based on the engine bench test, the effects with the Miller cycle application under 3000 rpm were studied. The results show that the Miller cycle has different extents of improvement on pumping loss, combustion and friction loss. For low, medium and high loads, the brake thermal efficiency of the baseline engine is increased by 2.8%, 2.5% and 2.6%, respectively. Besides, the baseline variable valve timing (VVT) is optimized by the test. Subsequently, the 1D CFD (Computational Fluid Dynamics) model of the Miller cycle engine after the test optimization at the working condition of 3000 rpm and BMEP (Brake Mean Effective Pressure) = 10 bar was established, and the influence of the combined change of intake and exhaust valve timing on Miller cycle was studied by simulation. The results show that as the effect of the Miller cycle deepens, the engine’s knocking tendency decreases, so the ignition timing can be further advanced, and the economy of the engine can be improved. Compared with the brake thermal efficiency of the baseline engine, the final result after simulation optimization is increased from 34.6% to 35.6%, which is an improvement of 2.9%.

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“…The Miller cycle is considered as a cold cycle and allows a lower NO X emission up to 40% -60% and increase the efficiency of the engine [29]. Furthermore, Miller cycle can be used on four stroke marine diesel engine to complete low scavenge air temperature [30], Figure 8.…”

Section: Diesel Engine Optimization Using Internal-treatmentmentioning

confidence: 99%

A Review and Comparison on Recent Optimization Methodologies for Diesel Engines and Diesel Power Generators

Issa¹,

Ibrahim²,

Lepage³

et al. 2019

JPEE

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The electrical instability that frequently distinguishes the isolated networks and depends on diesel generators to supply their energy requirements leads to an operation of the diesel generator in a transient dynamic condition and/or at low loads. In addition, extended operation of the diesel generator at partial load develops the condensation of combustion residues on the engine cylinder walls, which, after a certain time, increases friction, reduces the efficiency of the equipment and increases its fuel consumption. On the other hand, recent regulatory changes have led to ever more stringent and evolving emission standards. Among these, the International Maritime Organization (IMO) and the Environmental Protection Agency (EPA) have implemented emission standards in order to reduce exhaust gas emitted by marine diesel engines. To phase lower emission engines as soon as possible, a Tier system was adopted. This paper presents a literature review of existing technologies available to optimize the energy performance of diesel engines and diesel generators in order to reduce the cost of electricity, to increase the diesel engine efficiency and to decrease their fuel consumption and greenhouse gases (GHG) emissions. The proposed optimization methodologies are based on the application of Pre-treatment, Internal treatment and Post-treatment technologies for diesel engines and on the application of mechanical and electrical technologies for diesel power generators (DPGs). The list of references given at the end of the paper should offer aids for students and researchers working in this field.

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Potentials of the Miller Cycle on HD Diesel Engines Regarding Performance Increase and Reduction of Emissions

Cited by 19 publications

References 15 publications

Exploring the NOx Reduction Potential of Miller Cycle and EGR on a HD Diesel Engine Operating at Full Load

Exploring the NOx Reduction Potential of Miller Cycle and EGR on a HD Diesel Engine Operating at Full Load

Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load

A Review and Comparison on Recent Optimization Methodologies for Diesel Engines and Diesel Power Generators

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