HCCI with Wet Ethanol: Investigating the Charge Cooling Effect of a High Latent Heat of Vaporization Fuel in LTC

Gainey, Brian; Gohn, James; Yan, Zeng; Malik, Khurram; Boldaji, Mozhgan Rahimi; Lawler, Benjamin

doi:10.4271/2019-24-0024

Cited by 18 publications

(6 citation statements)

References 33 publications

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“…Another interesting result of this injection timing sweep is the large range of intake air temperature required to maintain a constant combustion phasing, also shown in Figure 2. As detailed in Gainey et al, 26 in HCCI, a constant combustion phasing implies a constant temperature at intake valve closing. Therefore, the large range of intake air temperatures measured upstream of the port is a result of the injection timing modulating the amount of fuel that evaporates off from the cylinder walls and piston crown versus evaporating in the incoming air and trapped residual gases, that is, a higher intake temperature is required when more fuel evaporates in the air.…”

Section: Resultsmentioning

confidence: 99%

“…In the previous work, it was imperative to inject the fuel into the piston bowl to minimize wall impingement; therefore, the combustion efficiency was highly sensitive to the start of injection (SOI) timing during the intake stroke. 15,26 Contrarily, this GDI engine employs a side-mounted GDI-style injector with a narrow spray included angle and a piston that lacks a deep bowl and squish region. Since combustion efficiency is largely unaffected by injection timing, as shown in Figure 2, the injection timing of −320° aTDC is selected for further studies.…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

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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“…More information on this thermodynamic model, including validation techniques, are given in Ref. [26].…”

Section: Thermodynamic Modelmentioning

confidence: 99%

“…A second injection delivers the remaining fuel during the middle of the compression stroke. 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].…”

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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“…Some early approaches were to retard the combustion phasing. 11,12 This approach is effective, but the trade-off is also significant. The retarded combustion phasing reduces the thermal efficiency from a thermodynamic standpoint.…”

Section: Introductionmentioning

confidence: 99%

Improving the controllability of partial fuel stratification at low boost levels by applying a double late injection strategy

Yan

Gainey

Hariharan

et al. 2020

International Journal of Engine Research

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This experimental study has two objectives. The first objective is to investigate the combustion performance of partial fuel stratification on a high compression ratio, light-duty diesel engine at a practical boost level of 1.6 bar. The second objective is to study the effects of a double late injection strategy on the ϕ-stratification gradient and combustion performance of partial fuel stratification, and verify the improvement in controllability with insufficient gasoline phi-sensitivity (i.e. gasoline does not exhibit strong phi-sensitivity at lower pressure conditions). The total targeted fuel flow rate was 16 mg/cycle throughout all of the experiments. Consequently, the global charge–mass equivalence ratio was fixed at 0.35. In order to investigate the combustion performance, start of injection timing sweeps were performed from –140° to –40° after top dead center, with the split fraction (i.e. the premixed fuel portion) varying from 70% to 90%. The combustion phasing was fixed at 8.6° after top dead center by adjusting the exhaust gas recirculation rate.

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HCCI with Wet Ethanol: Investigating the Charge Cooling Effect of a High Latent Heat of Vaporization Fuel in LTC

Cited by 18 publications

References 33 publications

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

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

Improving the controllability of partial fuel stratification at low boost levels by applying a double late injection strategy

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