Cylinder-to-cylinder variation sources in diesel low temperature combustion and the influence they have on emissions

Bittle, Joshua A.; Zheng, Junnian; Xue, Xingyu; Song, Hoseok; Jacobs, Timothy J.

doi:10.1177/1468087413481345

Cited by 25 publications

(7 citation statements)

References 15 publications

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“…As described in Experimental Methodology, the baseline combustion mode does not represent a practical light-load operating condition for modern-day diesel engines, because the NO emission is too high; regardless, it is chosen as the comparison mode to create stark contrasts for the purposes of studying LTHR at the light-load condition. Likewise, the BSNO emission for the LTC condition could be lowered further with higher EGR levels; this has been observed, however, to cause severe combustion instability and unacceptably high CO and HC emissions at the studied injection timing. , Regardless, the simultaneous reductions in BSNO and FSN are used to classify the studied conditions as LTC. Thus, the chosen EGR levels are considered appropriate representations of LTC, particularly in the context of the baseline combustion mode, since the LTC sweeps show simultaneous NO and FSN reductions relative to baseline combustion.…”

Section: Results and Discussionmentioning

confidence: 99%

Observed Differences in Low-Temperature Heat Release and Their Possible Effect on Efficiency between Petroleum Diesel and Soybean Biodiesel Operating in Low-Temperature Combustion Mode

Narayanan

Jacobs

2015

Energy Fuels

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Low-temperature combustion (LTC) in diesel engines has emerged as an enabling technology to simultaneously reduce oxides of nitrogen and smoke emissions. Combustion development continues to face challenges, however, with high emissions of carbon monoxide and unburned hydrocarbons and lower efficiencies than conventional combustion. Study of alternative fuels, such as biodiesel, with LTC shows varied promise of improving both combustion and fuel conversion efficiencies. The results are inconsistent, depending on the type of biodiesel (e.g., palm-based biodiesel relative to soy-based biodiesel). It was originally believed that differences in low-temperature heat release (LTHR) influence the phasing of main heat release (high-temperature heat release, or HTHR), thus creating differences in fuel conversion efficiencies among petroleum diesel and different types of biodiesels. This study attempts to address the issue of seemingly different LTHR behavior for different types of petroleum and biodiesel fuels between a baseline and LTC modes. Further, the study attempts to identify the effect, if any, that LTHR has on main heat release timing and rate. The study suggests, based on experimental analysis and reliance on observed behavior in literature, the roles that liquid and flame lift-off lengths and fuel chemical composition have on the appearance of LTHR in heat release profiles. The study further shows a disconnect between the extent of LTHR and the subsequent timing and rate of HTHR. Consequently, other factors seem to drive the phasing and extent of HTHR (which likely include the aforementioned parameters of liquid and flame lift-off lengths), which has a stronger influence on engine efficiency than the rate and timing of LTHR. ■ INTRODUCTIONEfficiency improvements of energy-converting devices, such as internal combustion engines, continue to be an important effort of research, particularly with the increased need to reduce atmospheric carbon emissions. Diesel engines, which typically offer higher fuel conversion efficiencies than other combustionoriented energy conversion technologies, could offer an opportunity to decrease such carbon emissions. There are other species present in diesel engine exhaust, however, which take a toll on human health and degrade the environment, including oxides of nitrogen (NO x ) and particulate matter (PM).Simultaneous reduction of NO x and PM in diesel engines is clearly desired. Conventional diesel combustion, however, does not permit this due to a complex temperature dependency of NO and soot formation and soot oxidation; 1 soot is a major component of PM. The simultaneous reduction can be obtained with use of low-temperature combustion (LTC). 2−7 One method to achieve LTC in a diesel engine phases combustion into the expansion stroke, where the two-stage ignition feature of some fuels can become visible 8−11 in the apparent rate of the heat release profile, calculated from the measured in-cylinder pressure. Two-stage ignition is a general term that recognizes the steady oxidat...

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Section: Results and Discussionmentioning

confidence: 99%

Observed Differences in Low-Temperature Heat Release and Their Possible Effect on Efficiency between Petroleum Diesel and Soybean Biodiesel Operating in Low-Temperature Combustion Mode

Narayanan

Jacobs

2015

Energy Fuels

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“…The cause of such cylinder−cylinder variations are the subject of a different study. 41 In that study, it is revealed that cylinder 3 is an anomaly cylinder; in that, it seems to receive less EGR than the other three and is used an injector that delivered relatively more fuel. Thus, through postulation, it seems that the gross indicated fuel conversion efficiency data of Figure 3 would be lower for petroleum diesel at the high EGR level conditions if it were not for cylinder 3 maintaining a reasonably phased burn profile.…”

Section: ■ Experimental Methodologymentioning

confidence: 95%

Low-Temperature Combustion with Biodiesel: Its Enabling Features in Improving Efficiency and Emissions

Tompkins

Jacobs

2013

Energy Fuels

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Low-temperature combustion is gaining interest for use in production reciprocating internal combustion engines because of its feature of simultaneously decreasing nitrogen oxides and smoke emissions. It faces, however, challenges of increased hydrocarbon (HC) and carbon monoxide (CO) emissions and decreased fuel conversion efficiency. In parallel, biodiesel is also gaining interest for use in production diesel engines as a potentially augmenting fuel to reduce petroleum-based fuel consumption. Combining the two, biodiesel and low-temperature combustion, results in improvements to both the emissions and efficiency challenges observed with petroleum-diesel-based low-temperature combustion. This work highlights the use of biodiesel with low-temperature combustion, in comparison to the same with petroleum diesel (ultralow sulfur diesel no. 2). The approach relies on experimental investigation of each fuel (in 100% concentrations) in a production medium-duty diesel engine as the exhaust gas recirculation level varies. Additionally, two fuel injection timings are studied: a "conventional combustion" timing of −8°after top dead center and a low-temperature combustion timing of 0°after top dead center. Biodiesel substantially improves combustion phasing, relative to petroleum diesel, of later-phased high-dilution low-temperature combustion for similar nitric oxide emissions and further improves cylinder−cylinder variations, both which mostly cause gross indicated fuel conversion efficiency to be about 6.5 percentage points (from 32.5 to 39%) higher for biodiesel than petroleum diesel. The improved combustion phasing with biodiesel is believed to result from both its decreased tendency of lowtemperature heat release and its oxygenated feature, the latter which allows for the transition to rapid heat release to occur much sooner than petroleum diesel. Increased CO and HC concentrations are also observed with petroleum diesel at the lowtemperature combustion condition (about 24 times higher for HC and 8 times higher for CO, relative to biodiesel); this is believed to result from the later-phased combustion of petroleum diesel and also causes its gross indicated fuel conversion efficiency to be lower relative to biodiesel. Finally, rates of heat transfer are substantially lower for petroleum diesel at the lowtemperature combustion condition, which would tend to improve its gross indicated fuel conversion efficiency. The lower rates of heat transfer of petroleum diesel, however, result from its poorly phased combustion at this condition, which ultimately deteriorates efficiency.

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“…Currently, most of these dual-fuel combustion strategies are studied in closely monitored laboratory environments on single cylinder engines. Once removed from the laboratory and implemented on multi-cylinder engines, combustion variations and phasing challenges begin to dominate [8][9][10]. One such challenge is the occurrence of more significant cylinder-to-cylinder variations that can lead to inconsistent power production and potentially damaging engine conditions.…”

Section: Introductionmentioning

confidence: 99%

Dual-Fuel Combustion

Kassa¹,

Hall²

2019

The Future of Internal Combustion Engines

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The implementation of a dual-fuel combustion strategy has recently been explored as a means to improve the thermal efficiencies of internal combustion engines while simultaneously reducing their emissions. Dual-fuel combustion is utilized in compression ignition (CI) engines to promote the use of more readily available gaseous fuels or more efficient, advanced combustion modes. Implementing dual-fuel injection technologies on these engines also allows (1) for improved control of the combustion timing by varying the proportion of two simultaneously injected fuels, and (2) for the use of more advanced combustion modes at high load since the two injected fuels ignite in succession reducing the high peak pressures that generally act as a limiting factor. In spark-ignited (SI) engines, the implementation of a dual-fuel combustion strategy serves as an alternative approach to avoid engine knock. The dual-fuel SI engine relies on the simultaneous injection of a low knock resistance and high knock resistance fuel to dynamically adjust the fuel mixture's resistance to knock as required. The dual-fuel SI engine thereby successfully suppresses knock without compromising the engine efficiency. This chapter discusses the technological advancements associated to dual-fuel combustion and the respective gains in fuel efficiency and emissions reductions that have been achieved.

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Cylinder-to-cylinder variation sources in diesel low temperature combustion and the influence they have on emissions

Cited by 25 publications

References 15 publications

Observed Differences in Low-Temperature Heat Release and Their Possible Effect on Efficiency between Petroleum Diesel and Soybean Biodiesel Operating in Low-Temperature Combustion Mode

Observed Differences in Low-Temperature Heat Release and Their Possible Effect on Efficiency between Petroleum Diesel and Soybean Biodiesel Operating in Low-Temperature Combustion Mode

Low-Temperature Combustion with Biodiesel: Its Enabling Features in Improving Efficiency and Emissions

Dual-Fuel Combustion

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