LPL EGR and D-EGR® Engine Concept Comparison Part 2: High Load Operation

Gukelberger, Raphael; Gingrich, Jess; Alger, Terrence; Almaraz, Steven; Denton, Bradley

doi:10.4271/2015-01-0781

Cited by 24 publications

(6 citation statements)

References 17 publications

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“…Further, on-engine demonstrations of dEGR implemented on comercially available gasoline engines were performed by researchers at Southwest Research Institute. 15–24 These demonstrations continued to focus on improving engine efficiency by increased CR, boosting, and the development of the patented dEGR mixer.…”

Section: Introductionmentioning

confidence: 99%

Evaluating dedicated exhaust gas recirculation on a stoichiometric industrial natural gas engine

Roekel

Montgomery

Singh

et al. 2019

International Journal of Engine Research

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Due to the market presence that natural gas has and is expected to have in the future energy sector, research and development of novel natural gas combustion strategies to increase power density, lower total emissions, and increase overall efficiency is warranted. Dilution whether by excess air or by exhaust gas recirculation has historically been implemented on diesel, natural gas, and gasoline engines to mitigate various regulated emissions. In the large industrial natural gas engine industry, excess air dilution or ultra-lean-burn operation has afforded lean-burn engines increased power density and reduced NO x emissions. This advance in technology has allowed lean-burn engines to compete in markets such as electrical power generation which previously they had not been able. However, natural gas engines utilizing a non-selective catalytic reduction system or three-way catalyst must operate under stoichiometric conditions and thus are limited in power density by exhaust gas temperatures. In previous gasoline small engine research, a novel exhaust gas recirculation technique called dedicated exhaust gas recirculation was shown to have a positive impact on engine-out emissions of NO x and unburned hydrocarbons while also lowering exhaust component temperatures. This work seeks to understand the consequences of implementing a dedicated exhaust gas recirculation system on a multi-cylinder stoichiometric industrial natural gas engine. The results of this initial evaluation demonstrate reductions in engine-out NO x and CO emissions and improvements in engine-out exhaust gas temperatures with the dedicated exhaust gas recirculation technique. However, in a low-turbulence combustion chamber, dedicated exhaust gas recirculation significantly lowers the overall rate of combustion and results in significant differences in cylinder-to-cylinder combustion.

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Section: Introductionmentioning

confidence: 99%

Evaluating dedicated exhaust gas recirculation on a stoichiometric industrial natural gas engine

Roekel

Montgomery

Singh

et al. 2019

International Journal of Engine Research

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“…For the assumptions made, this number agrees reasonably well with previous experimental engine data, which show that a dedicated EGR engine was adapted from an engine with compression ratio of 9.1 to an engine with compression ratio of 12.5 (an increase of 3.4 compression ratio, compared with a predicted increase of 3.53 in this work) while operating with 25% cooled EGR and a rich cylinder equivalence ratio of 1.3. 57–59 More optimal (advanced) combustion phasing used in the demonstration engine could more than account for the discrepancy with this work, although potential differences in the boost level and IVC temperature (as a results of residuals or heat exchanger effectiveness) would also play an important role.…”

Section: Resultsmentioning

confidence: 62%

“…17,53–55 Among these systems is the dedicated EGR engine—an advanced SI engine, which has been integrated into a demonstration vehicle. 56–58 The key feature of this engine is that it has been modified so that one cylinder continuously runs rich, to generate reformate gas (primarily CO and H 2 ) that recirculates through an EGR cooler and back to the intake. The engine thus operates with a nominal rate of 25% cooled EGR over the entire engine map, allowing it to employ a 12.5:1 geometric compression ratio.…”

Section: Resultsmentioning

confidence: 99%

“…The engine thus operates with a nominal rate of 25% cooled EGR over the entire engine map, allowing it to employ a 12.5:1 geometric compression ratio. 57,59…”

Section: Resultsmentioning

confidence: 99%

“…The engine thus operates with a nominal rate of 25% cooled EGR over the entire engine map, allowing it to employ a 12.5:1 geometric compression ratio. 57,59 The rich cylinder in this engine can operate at an equivalence ratio of up to 1.3, resulting in a product gas that is estimated to contain as much as 3.2 vol.% hydrogen and 7.5 vol.% carbon monoxide 17 with the balance being H 2 O, CO 2 and N 2 determined from the carbon and hydrogen balance (once blended with the intake, the concentration of H 2 and CO in the end-gas falls to 0.80 and 1.9 vol.%, respectively). Rich conditions produce the most reformate: increasing the rich cylinder equivalence ratio from 1.1 to 1.5 is expected to increase hydrogen by more than a factor of 5 and carbon monoxide by more than a factor of 3 ( Figure 16).…”

Section: Evaluation Of a Practical Onboard Reforming Systemmentioning

confidence: 99%

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Quantification of knock benefits from reformate and cooled exhaust gas recirculation using a Livengood–Wu approach with detailed chemical kinetics

Marsh

Voice

2016

International Journal of Engine Research

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In this work, a simple methodology was implemented to predict the onset of knock in spark-ignition engines and quantify the benefits of two practical knock mitigation strategies: cooled exhaust gas recirculation and syngas blending. Based on the results of this study, both cooled exhaust gas recirculation and the presence of syngas constituents in the end-gas substantially improved the knock-limited compression ratio of the engine. At constant load, 25% exhaust gas recirculation increased the knock-limited compression ratio from 9.0 to 10.8:1 (0.07 compression ratio per 1% exhaust gas recirculation) due to lower end-gas temperature and reactant (fuel and oxygen) concentrations. At exhaust gas recirculation rates above 43%, higher intake temperature outweighed the benefits of lower end-gas reactant concentration. At constant intake temperature, cooled exhaust gas recirculation was significantly more effective at all exhaust gas recirculation rates (0.10 compression ratio per 1% exhaust gas recirculation), and no diminishing returns or optimum was observed. Both hydrogen and carbon monoxide were also predicted to improve knock by reducing end-gas reactivity, likely through the conversion of high-reactivity hydroxy-radicals to less reactive peroxy-radicals. Hydrogen increased the knock-limited compression ratio by 1.1 per volume percent added at constant energy content. Carbon monoxide was less effective, increasing the knock-limited compression ratio by 0.38 per volume percent added. Combining 25% cooled exhaust gas recirculation with reformate produced from rich combustion at an equivalence ratio of 1.3 resulted in a predicted increase in the knock-limited compression ratio of 3.5, which agreed well with the published experimental engine data. The results show the extent to which syngas blending and cooled exhaust gas recirculation each contribute separately to knock mitigation and demonstrate that both can be effective knock mitigation strategies. Together, these solutions have the potential to increase the compression ratio and efficiency of spark-ignition engines.

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