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

Tompkins, Brandon T.; Jacobs, Timothy J.

doi:10.1021/ef302076y

Cited by 15 publications

(20 citation statements)

References 42 publications

(61 reference statements)

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“…The first feature to note is, as expected, both CO and HC increase as EGR level increases. This is a common observation of long-ignition delay LTC conditions 15 and is, from the unburned HC perspective, studied elsewhere. 43 The second, perhaps surprising, feature to note is the higher concentrations of CO and HC with biodiesel compared to petroleum diesel.…”

Section: Energy and Fuelsmentioning

confidence: 57%

“…43 The second, perhaps surprising, feature to note is the higher concentrations of CO and HC with biodiesel compared to petroleum diesel. Early studies of biodiesel LTC 15,16 and studies of conventional biodiesel combustion 44 show lower HC and/or CO with biodiesel. The discrepancy in this study, with Figure 7, is likely due to this study's use of soybased biodiesel, where ignition delays are similar to petroleum diesel LTC (see Figures 4 and 5), and likely due to cetane numbers similar to those shown in Table 2.…”

Section: Energy and Fuelsmentioning

confidence: 99%

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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: Energy and Fuelsmentioning

confidence: 57%

Section: Energy and Fuelsmentioning

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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“…Biodiesel contains 10% (wt) oxygen, so there is an additional possibility of reducing pollutants from incomplete combustion, such as HC, CO, and PM, that are the main issues in LTC. The affirmative influence in emissions using biodiesel LTC has been proven in the literature. , Tompkins et al applied palm oil biodiesel in a four-cylinder medium-duty diesel engine . LTC was achieved by late injection (0 CAD bTDC) and a high level of EGR (∼50%) with an injection pressure of 816 bar.…”

Section: Introductionmentioning

confidence: 98%

Biodiesel PCI Combustion for Performance and Emission Improvement in a Compression Ignition Engine

2021

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Low-temperature combustion has the potential to reduce nitrogen oxides (NO x ) and particulate matter (PM) emissions; however, it faces the challenge of high level of hydrocarbon (HC) and carbon monoxide (CO) emissions. Application of oxygenated fuel such as biodiesel to LTC has gained interest to overcome this drawback. This study aims to provide a comprehensive understanding of the influence of biodiesel on premixed compression ignition (PCI) in a single-cylinder compression ignition engine. A series of engine tests were carried out at an engine speed of 1200 rev/min with two injection pressures (800 bar and 1600 bar), two injection timings (25 and 5 crank angle degree (CAD) before top dead center (bTDC)), and four exhaust gas recirculation (EGR) rates (0–30%). Engine performance results showed that fuel consumption with PCI combustion was higher than that with conventional diesel combustion (CDC) due to the advanced combustion phase. The lower heating value of biodiesel resulted in approximately 10% higher fuel consumption than diesel regardless of test conditions. In terms of emissions, PCI combustion indicated higher carbon CO and HC emissions because of liquid fuel flow in squish areas with early injection timing supported by a Lagrangian spray simulation. However, the application of biodiesel in PCI combustion was beneficial to suppress CO and HC emissions while maintaining low levels of NO x and PM emissions compared to CDC condition. Especially, the PN emission under PCI biodiesel condition was 1/10 of CDC. Soot morphology by TEM imaging showed a smaller primary particle diameter with biodiesel, attributed to enhanced soot oxidation.

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“…Diesel engine nitrogen oxides (NOx) and soot emissions adversely affect human health and the environment [2]. NOx is a lung irritant and a precursor to ozone formation [3].…”

Section: Introductionmentioning

confidence: 99%

Detailed Analysis of the Effects of Biodiesel Fraction Increase on the Combustion Stability and Characteristics of a Reactivity-Controlled Compression Ignition Diesel-Biodiesel/Natural Gas Engine

Zarrinkolah

Hosseini

2022

Energies

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A single-cylinder marine diesel engine was modified to be operated in reactivity controlled compression ignition (RCCI) combustion mode. The engine fueling system was upgraded to a common rail fuel injection system. Natural gas (NG) was used as port fuel injection, and a diesel/sunflower methyl ester biodiesel mixture was used for direct fuel injection. The fraction of biodiesel in the direct fuel injection was changed from 0% (B0; 0% biodiesel and 100% diesel) to 5% (B5) and 20% (B20) while keeping the total energy input into the engine constant. The objective was to understand the impacts of the increased biodiesel fraction on the combustion characteristics and stability, emissions, and knocking/misfiring behavior, keeping all other influential parameters constant. The results showed that nitrogen oxides (NOx) emissions of B5 and B20 without the need for any after-treatment devices were lower than the NOx emission limit of the Euro VI stationary engine regulation. B5 and B20 NOx emissions decreased by more than 70% compared to the baseline. Significantly more unburned hydrocarbons (UHCs) and carbon monoxide (CO) emissions were produced when biodiesel was used in the direct fuel injection (DFI). The results also showed that using B5 and B20 instead of B0 led to an increase of 18% and 13.5% in UHCs and an increase of 88.5% and 97% in CO emissions, respectively. Increasing the biodiesel fraction to B5 and B20 reduced the maximum in-cylinder pressure by 3% and 10.2%, respectively, compared to B0. Combustion instability is characterized by the coefficient of variation (COV) of the indicated mean effective pressure (IMEP), which was measured as 4.2% for B5 and 4.8% for B20 compared to 1.8% for B0. Therefore, using B20 and B5 resulted in up to 34.9% combustion instabilities, and 18.5% compared to the baseline case. The tendency for knocking decreased from 13.7% for B0 to 4.3% for B20. The baseline case (B0) had no misfiring cycle. The B5 case had some misfiring cycles, but no knocking cycle was observed. Moreover, the historical cyclic analysis showed more data dispersions when the biodiesel fraction increased in DFI. This study shows the potential of biodiesel replacement in NG/diesel RCCI combustion engines. This study shows that biodiesel can be used to effectively reduce NOx emissions and the knocking intensity of RCCI combustion. However, combustion instability needs to be monitored.

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

Cited by 15 publications

References 42 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

Biodiesel PCI Combustion for Performance and Emission Improvement in a Compression Ignition Engine

Detailed Analysis of the Effects of Biodiesel Fraction Increase on the Combustion Stability and Characteristics of a Reactivity-Controlled Compression Ignition Diesel-Biodiesel/Natural Gas Engine

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