Analysis of Water Injection Strategies to Exploit the Thermodynamic Effects of Water in Gasoline Engines by Means of a 3D-CFD Virtual Test Bench

Vacca, Antonino; Bargende, Michael; Chiodi, Marco; Franken, Tim; Netzer, Corinna; Gern, Maike Sophie; Kauf, Malte; Kulzer, André

doi:10.4271/2019-24-0102

Cited by 25 publications

(12 citation statements)

References 12 publications

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“…The mixture is initialized homogeneously, and the effects of water wall film formation, water inhomogeneity, water–oil dilution and incomplete water vaporization are not considered. Those effects are stated to be important for the efficiency of water injection, 23,51,52 and the predicted trends in this work can be changed by those effects.…”

Section: Resultsmentioning

confidence: 77%

Gasoline engine performance simulation of water injection and low-pressure exhaust gas recirculation using tabulated chemistry

Franken

Mauß

Seidel³

et al. 2020

International Journal of Engine Research

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This work presents the assessment of direct water injection in spark-ignition engines using single cylinder experiments and tabulated chemistry-based simulations. In addition, direct water injection is compared with cooled low-pressure exhaust gas recirculation at full load operation. The analysis of the two knock suppressing and exhaust gas cooling methods is performed using the quasi-dimensional stochastic reactor model with a novel dual fuel tabulated chemistry model. To evaluate the characteristics of the autoignition in the end gas, the detonation diagram developed by Bradley and co-workers is applied. The single cylinder experiments with direct water injection outline the decreasing carbon monoxide emissions with increasing water content, while the nitrogen oxide emissions indicate only a minor decrease. The simulation results show that the engine can be operated at λ = 1 at full load using water–fuel ratios of up to 60% or cooled low-pressure exhaust gas recirculation rates of up to 30%. Both technologies enable the reduction of the knock probability and the decrease in the catalyst inlet temperature to protect the aftertreatment system components. The strongest exhaust temperature reduction is found with cooled low-pressure exhaust gas recirculation. With stoichiometric air–fuel ratio and water injection, the indicated efficiency is improved to 40% and the carbon monoxide emissions are reduced. The nitrogen oxide concentrations are increased compared to the fuel-rich base operating conditions and the nitrogen oxide emissions decrease with higher water content. With stoichiometric air–fuel ratio and exhaust gas recirculation, the indicated efficiency is improved to 43% and the carbon monoxide emissions are decreased. Increasing the exhaust gas recirculation rate to 30% drops the nitrogen oxide emissions below the concentrations of the fuel-rich base operating conditions.

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Section: Resultsmentioning

confidence: 77%

Gasoline engine performance simulation of water injection and low-pressure exhaust gas recirculation using tabulated chemistry

Franken

Mauß

Seidel³

et al. 2020

International Journal of Engine Research

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“…Limits to knock mitigation synergies of EIVC and water injection were evidenced, with combustion stability eventually suffering, as shown in Figure 44. Vacca and Bargende [314] of the University of Stuttgart, together with collaborators at Brandenburg University of Technology and Porsche, presented a simulation approach to validate various water injection strategies. Chemical kinetics were included in CONVERGE 3D CFD software, and the Bradley detonation diagram was used to interpret results.…”

Section: The 2010s: Aggressive Co 2 Targets Electrification and Downs...mentioning

confidence: 99%

Knock: A Century of Research

Corrigan¹,

Fontanesi²

2021

SAE Int. J. Engines

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Knock is one of the main limitations on increasing spark-ignition (SI) engine efficiency. This has been known for at least 100 years, and it is still the case today. Knock occurs when conditions ahead of the flame front in an SI engine result in one or more autoignition events in the end gas. The autoignition reaction rate is typically much higher than that of the flame-front propagation. This may lead to the creation of pressure waves in the combustion chamber and, hence, an undesirable noise that gives knock its name. The resulting increased mechanical and thermal loading on engine components may eventually lead to engine failure. Reducing the compression ratio lowers end-gas temperatures and pressures, reducing end-gas reactivity and, hence, mitigating knock. However, this has a detrimental effect on engine efficiency.Automotive companies must significantly reduce their fleet carbon dioxide (CO 2 ) values in the coming years to meet targets resulting from the 2015 Paris Agreement. One path towards meeting these is through partial or full electrification of the powertrain. However, the vast majority of automobiles in the near future will still feature a gasoline-fueled SI engine; hence, improvements in combustion engine efficiency remain fundamental.As knock has been a key limitation for so long, there is a huge amount of literature on the subject. A number of reviews on knock have already been published, including in recent years. These generally concentrate on current understanding and status. The present work, in contrast, aims to track the progress of research on knock from the 1920s right through to the present day. It is hoped that this can be a useful reference for new and existing researchers of the subject and give further weight to occasionally neglected historical activity, which can still provide important insights today.

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“…Future research should focus on alternative fuels and combustion strategies (e.g. water injection [116] and split cycle engines [117]). Due to detailed chemical kinetics libraries available within the chosen SRM combustion model, it is expected that the developed methodology will predict the effect of different fuels.…”

Section: Future Workmentioning

confidence: 99%

A process for an efficient heat release prediction at the concepts screening stage of gasoline engine development

Rota

Morgan

Mustafa

et al. 2020

International Journal of Engine Research

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In recent years, the exploration of new combustion technologies has accelerated in response to increasingly stringent emissions regulations and fuel economy demands. Virtual engineering tools, that enable the screening of novel hardware and engine calibrations at the early stage of engine development, have become imperative to meet new emission regulations. One-dimensional engine simulations are used at the start of the design of a new engine to define the overall combustion system geometries. Later, more complex three-dimensional computational fluid dynamics calculations are coupled to one-dimensional engine system codes to optimise initial concept geometries and define a system design ready for prototyping. To provide meaningful results, one-dimensional engine system codes often use empirical-based combustion models to calculate the engine burn rate. Moreover, realistic engine burn rates responses, for the entire engine map and for different calibrations, are required to provide three-dimensional computational fluid dynamics codes with correct boundary conditions during the design optimisation phase. Thus, the burn characteristic of new non-traditional combustion solution, for which little experimental data are available, needs to be initially assumed. To improve virtual development and reduce this uncertainty, the industry’s attention shifted towards quasi-dimensional combustion models capable of providing engine burn rate predictions. Within the quasi-dimensional modelling framework, turbulence models, adding extra user-input variables, are required to capture the effect of different combustion chamber geometries on the engine combustion rate. Rigorous validation of zero-dimensional turbulence models for different engine concepts and calibrations is therefore needed to enable quasi-dimensional combustion models to predict the engine burn rate. An alternative methodology, with limited dependency on previous test data, is required to enhance the exploration of novel combustion strategies and geometric architectures. An available process, based on a quasi-dimensional combustion stochastic reactor model, a one-dimensional engine system model and non-combusting three-dimensional computational fluid dynamics calculations, was used for this work. The approach uses limited non-combusting computational fluid dynamics calculations and a previously developed scaling factor response for the stochastic reactor model turbulence input ( τSRM) to quickly predict the engine rate of heat release. In this work, the scaling factor response was assessed against two different engine variants over a variety of engine operating conditions. Moreover, the same response was used to predict the effect of different bore-to-stroke ratios on the engine combustion rate and knock tolerance. Non-combusting computational fluid dynamics and one-dimensional engine system simulations have been carried out to investigate changes in turbulence characteristics due to different engine variants and bore-to-stroke ratios. It was shown that limited number of non-combusting computational fluid dynamics runs is required to characterise the in-cylinder turbulence for each explored engine variant. The scaling factor response was used to manipulate the turbulence input ( τSRM) resulting in good engine burn rates predictions for the explored engine variants and bore-to-stroke ratios. The presented methodology showed augmented predictive capabilities and has potential to move the engine development towards a less hardware dependent virtual approach, offering a practical solution for the exploration of new engine concepts.

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Analysis of Water Injection Strategies to Exploit the Thermodynamic Effects of Water in Gasoline Engines by Means of a 3D-CFD Virtual Test Bench

Cited by 25 publications

References 12 publications

Gasoline engine performance simulation of water injection and low-pressure exhaust gas recirculation using tabulated chemistry

Gasoline engine performance simulation of water injection and low-pressure exhaust gas recirculation using tabulated chemistry

Knock: A Century of Research

A process for an efficient heat release prediction at the concepts screening stage of gasoline engine development

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