Investigating the effect of spray included angle on thermally stratified compression ignition with wet ethanol using computational fluid dynamics

Boldaji, Mozhgan Rahimi; Gainey, Brian; O'Donnell, Patrick Christopher; Gohn, James; Lawler, Benjamin

doi:10.1016/j.applthermaleng.2020.114964

Cited by 15 publications

(4 citation statements)

References 55 publications

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“…Mesh has a 4 mm base grid [5]. The combustion chamber mesh size is 1 mm and 0.25 around the injector.…”

Section: Mesh Generationmentioning

confidence: 99%

Effect of water injector location on combustion and performance of an HCCI engine - A CFD analysis

Naik,

Mallikarjuna

2024

J. Phys.: Conf. Ser.

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A homogeneous charge compression ignition (HCCI) engine is capable of producing high thermal efficiency with very low emissions. However, because of the limited upper load level constrained by knocking, the HCCI engine is not yet commercialized. Water injection can tackle this issue, enhancing the upper load limit without excessive heat release rate. However, the effectiveness of water injection depends on in-cylinder water evaporation, which in turn depends on water injection parameters. Therefore, this study is conducted to study the effect of water injector location on the combustion and performance characteristics of an HCCI engine by a computational fluid dynamic (CFD) analysis. The engine specifications and boundary conditions are taken from the literature. A three-dimensional computational fluid dynamics (3D CFD) model was developed using CONVERGE CFD coupled with detailed chemical kinetics to gain a better understanding of the phenomena of water injection in an HCCI engine. The CFD models used are validated from the available experimental data in the literature for the engine considered. Here, the water injector location is optimized based on the Water vapor distribution within the cylinder, nitric oxide (NOx) emissions, and maximum rate of pressure rise (MRPR). The results show that the water injector at 37 mm from the center of the cylinder gives better results than in other cases considered. With the optimum water injector location, the indicated mean effective pressure is increased by about 35.91% than without the water injection case. This study will be helpful in the development of HCCI engines.

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“…Mesh has a 4 mm base grid [5]. The combustion chamber mesh size is 1 mm and 0.25 around the injector.…”

Section: Mesh Generationmentioning

confidence: 99%

Effect of water injector location on combustion and performance of an HCCI engine - A CFD analysis

Naik,

Mallikarjuna

2024

J. Phys.: Conf. Ser.

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“…More specifically, the compression stroke injection's ability to enhance thermal stratification is strongly related to the region in the cylinder that is targeted by the spray. 32,33 With this in mind, if a split injection strategy is employed on the engine considered in this study, compression stroke injections may actually reduce overall in-cylinder stratification.…”

Section: Controlling In-cylinder Stratification With a Split Injectio...mentioning

confidence: 99%

Tailoring thermal stratification to enable high load low temperature combustion with wet ethanol on a gasoline engine architecture

Gainey

Yan

Moser

et al. 2020

International Journal of Engine Research

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Wet ethanol is a biofuel with unique fuel properties: a high latent heat of vaporization and low equivalence ratio sensitivity. These two fuel properties enable control over the heat release process in low temperature combustion through the enhancement of in-cylinder thermal stratification. In this work, it is shown that the direct injection of wet ethanol 80 (80% ethanol, 20% water, by mass) during the intake stroke on a mid-compression ratio engine with a side-mounted gasoline direct injector does not fully premix with incoming air, leaving stratification in the cylinder which elongates the combustion process, enabling high-load low temperature combustion without engine-damaging knock. As a result, the load under naturally aspirated conditions was only limited by oxygen content as the global equivalence ratio approached stoichiometry. The results show that swirl can not only modulate the induced stratification effectively by increasing the amount of bulk motion in the cylinder but also cause a thermal efficiency penalty, since swirl increases heat transfer losses. Modulation over the induced stratification can be achieved without an efficiency penalty by employing either a dual injector system where a fraction of the total fuel is injected into the port or a split injection strategy where a fraction of the total fuel is injected during the compression stroke. This strategy enables high-load low temperature combustion, while reducing the number of regions that form NOx and avoiding excessively rich regions that contribute to combustion inefficiency.

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“…The injection timing of both injections as well as the split fraction between the two injections have proven to be effective control knobs over the start and rate of combustion [25,26]. Previous work also showed that this strategy works best when coupled with an injector that can aim the compression stroke injection towards regions in the combustion chamber that have the highest local relative heat transfer rates, e.g., a wide spray angle aiming towards the squish region [27]. This allows the evaporative cooling to work with the natural thermal stratification, rather than against it, minimizing the required stratification and thereby minimizing NOx formation.…”

Section: Introductionmentioning

confidence: 99%

High Load Compression Ignition of Wet Ethanol Using a Triple Injection Strategy

et al. 2022

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Wet ethanol is a biofuel that can be rapidly integrated into the existing transportation sector infrastructure and have an immediate impact on decarbonization. Compared to conventional hydrocarbon fuels, wet ethanol has unique fuel properties (e.g., short carbon chain, oxygenated, high heat of vaporization, no cool-flame reactivity), which can actually improve the efficiency and engine-out emissions of internal combustion engines while decarbonizing. In this work, wet ethanol 80 (80% ethanol, 20% water by mass) was experimentally studied at high loads under boosted conditions in compression ignition to study the tradeoffs in efficiency and emissions based on boosting and injection strategies. Specifically, this work explores the potential of adding a third, mixing-controlled injection at high loads. The results indicate that adding a third, mixing-controlled injection results in combustion stabilization at high loads, where the peak pressure limit of the engine is a constraint that requires combustion phasing to retard. However, since the heat of vaporization of wet ethanol 80 is ~6% of its lower heating value, evaporation of fuel injected near top dead center imposes a thermodynamic efficiency penalty by absorbing heat from the working fluid at a time in the cycle when adding heat produces net work out. Additionally, the mixing-controlled injection increases NOx emissions. Therefore, the amount of fuel injected in the mixing-controlled injection should be limited to only what is necessary to stabilize combustion. Ultimately, by using wet ethanol 80 in a triple injection strategy, a load of 22 bar IMEPn is achieved with a net fuel conversion efficiency of 42.2%, an engine-out indicated specific emissions of NOx of 1.3 g/kWh, and no measurable particulate matter, while maintaining a peak cylinder pressure below 150 bar.

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Investigating the effect of spray included angle on thermally stratified compression ignition with wet ethanol using computational fluid dynamics

Cited by 15 publications

References 55 publications

Effect of water injector location on combustion and performance of an HCCI engine - A CFD analysis

Effect of water injector location on combustion and performance of an HCCI engine - A CFD analysis

Tailoring thermal stratification to enable high load low temperature combustion with wet ethanol on a gasoline engine architecture

High Load Compression Ignition of Wet Ethanol Using a Triple Injection Strategy

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