Cetane Number Research Articles

Investigation on combustion and emission characteristics of diesel polyoxymethylene dimethyl ethers blend fuels with exhaust gas recirculation and double injection strategy

As a kind of renewable and high oxygen content fuel, polyoxymethylene dimethyl ether (PODE) can be added in diesel to realize energy saving and emissions reduction. To evaluate the combustion and emission characteristics of a diesel engine fueled with diesel and diesel/PODE mixtures, exhaust gas recirculation (EGR) and main-pilot injection strategies with various injection timings were applied. PODE was blended with diesel by volume to form mixtures which were marked as D100 (pure diesel), D90P10 (90% diesel + 10% PODE), and D80P20 (80% diesel + 20% PODE). The results showed that the ignition delay (ID) and combustion duration (CD) of D80P20 were the shortest because of the highest cetane number (CN) and high oxygen content of PODE, indicating more concentrated heat release. At low and medium loads, D80P20 achieved the highest peak heat release ratio (PHRR) and peak combustion temperature (PCT) among the three fuels, and it was 14.3% and 3.6% higher than those of D100. PODE blending with diesel can significantly reduce particulate matter (PM) and D80P20 has the lowest PM emissions at all loads. Compared with D100, both PM and nitrogen oxide (NOx) emissions of PODE blends decreased simultaneously with 20% EGR at all loads. With the increase of pilot-main interval, the ID and CD of all test fuels increased, while the NOx and PM emissions decreased. The conclusions of the present research provide a state of the application in light-duty engines fueled with diesel/PODE blends in future work.

Comparison of the physicochemical properties of microalgae biodiesel with other oilseed feedstocks for sustainable energy production: A meta-analysis

Biodiesel has emerged as an alternative diesel fuel, offering environmental advantages such as biodegradability, non-toxicity, and low emissions. This study conducted a meta-analysis to compare microalgae biodiesel with other oilseed feedstocks for sustainable energy production. The analysis involved compiling a database of published articles on biodiesel derived from microalgae and plant seeds. The results demonstrated that microalgae are one of the most promising feedstocks among various oilseeds. The cetane number and fuel density of biodiesel from microalgae were significantly higher than those from plant seeds (p<0.05). In conclusion, microalgae are a suitable feedstock for biodiesel production, surpassing traditional oil and crop sources, and can potentially mitigate the expansion of conventional agricultural practices. Moreover, microalgae can be cultivated year-round and in various climates, allowing for extended production seasons and site flexibility. Additionally, their utilization of waste streams as nutrient sources and non-requirement of arable land can contribute to reducing the environmental impact on other industries.

Investigating the potential of a higher reactivity fuel to achieve faster heat-up of aftertreatment systems

Shortening the aftertreatment system heat-up period will be crucial to meet upcoming emissions regulations, which mandate significant reductions in tail-pipe emissions for on-road heavy-duty vehicles. This work studies the impact of increasing fuel reactivity on the combustion of post injections during the expansion stroke. The work demonstrates an operating strategy using a blend of di-butyl ether (a potential low-carbon biofuel component) and #2 diesel that achieves higher exhaust enthalpy, while maintaining similar engine-out emissions (NOx and combustion efficiency) in comparison to the baseline #2 diesel fuel (cetane number 41). On average, a 12% increase in exhaust enthalpy was observed for the blend (cetane number 60) relative to the baseline fuel. The ability to operate the higher reactivity fuel at a more retarded post-injection timing, where combustion with #2 diesel was found to be more unstable, and less complete was key to achieving higher exhaust enthalpy. However, a small fuel penalty (∼ 3%–5%) was also associated with the higher reactivity fuel with this operating strategy. The formation of fuel lean regions, due to the long ignition delays at late injection conditions, was predicted to be the leading contributor to the increased emissions of products of partial combustion. Chemical kinetic simulations using surrogates for the fuels used in the experiments, demonstrated the ability of a higher cetane fuel to outperform the baseline fuel under fuel lean conditions with equivalence ratios less than 0.7.

Evaluation of Auto-Ignition Characteristics of Diesel Surrogate Fuels with the Same Derived Cetane Numbers at Changed Thermodynamic Environments

Evaluation of Auto-Ignition Characteristics of Diesel Surrogate Fuels with the Same Derived Cetane Numbers at Changed Thermodynamic Environments

Algal consortia as the flexible bio-system for wastewater treatment: Effect of different light intensities on photosynthetic performance, anti-oxidative system and biodiesel production of consortia

Competence of microalgae consortia-1 (Chlorococcum humicola and Tetradesmus sp.) and consortia-2 (Chlorococcum humicola, Scenedesmus vacuolatus and Tetradesmus sp.) was analyzed by examining their adaptability potential in wastewater under different light intensities (20 W/m2 and 40 W/m2). The results depicted highest decline in nutrients and metal concentration (40–90%) at light intensity of 40 W/m2 by consortia-1 and consortia-2 treated with wastewater (50%, 100%). The result of metal remediation was further confirmed by fourier transform infrared spectroscopy (FTIR) which reflected occurrence of different functional groups in selected consortia. Moreover, light intensity of 40 W/m2 induced neutral-lipid accumulation (1750 cm−1) in consortia-1 as depicted in FTIR spectra. The maximum active photosystem-II reaction center (79.75%), quantum yield (26.17%) and performance index (195.8%) revealed that light intensity (40 W/m2) and wastewater augmented functioning of photosystem-II in consortia-1 than consortia-2. Further, consortia-2 appeared more sensitive to oxidative stress as the concentration of oxidative stress markers (5.73–6.39 folds) was amplified after treatment with wastewater at light intensity of 40 W/m2. The prodigious tolerance potential towards different light intensities and wastewater concentration of consortia-1 may be attributed to increased activity of ascorbic acid (1.16 folds), proline (1.32 folds), cysteine (2.80 folds), superoxide dismutase (3.44 folds), catalase (2.52 folds) and glutathione reductase (1.90 folds). However, abundance of saturated fatty acid (41.34%) together with high cetane number (59.07) indicated that consortia 2 can produce excellent quality biofuel at 20 W/m2 while consortia-2 at 40 W/m2. Overall, consortia 1 appeared competent in terms of photosynthetic performance, remediation efficiency and antioxidant defense mechanism under 20 W/m2 and 40 W/m2 while consortia-2 showed quality biodiesel production at 20 W/m2. Thus, algal consortia based on photosynthetic performance and defense responses along with excellent biodiesel quality under different light intensity and wastewater concentration can serve as the promising biosystem for biomass and bioenergy production.

OBTAINING ADDITIVES USED TO IMPROVE THE CHARACTERISTICS OF DIESEL FUEL

One of the important large-scale petroleum refining products is diesel fuel (DF). It ensures the continuous operation of the transport fleet of various industries, and is also widely used by individual consumers. The chemical and fractional composition of diesel fuel determines the environmental temperature conditions in which diesel fuel (DF) can be used. There are diesel engines for temperate and cold climates. There is a serious shortage in the production of diesel fuel with improved low-temperature properties; the existing demand is covered by less than half [1]. In fact, in 2014, the production of diesel fuel amounted to 2.2% of the total output. The need for low-solidification fuels for our country, taking into account its natural and climatic conditions, is 40%. Thus, the importance of measures aimed at reducing the existing deficit is beyond doubt. The main goal of the article is to develop methods for the production and use of new additives and additives based on domestic petrochemical products. The cetane number of diesel fuel is one of the most important indicators responsible for reliable engine operation. The use of diesel fuel with a cetane number below 40 leads to harsh engine operation, accompanied by increased wear and its gradual destruction [4]. If the cetane number becomes more than 60 points, the power of the internal combustion engine (ICE) decreases, the fuel does not burn completely, fuel consumption increases, and the exhaust gases contain soot [5]. Keywords: diesel fuel, additives, cetane number, dewaxing, low temperature properties.

Descriptors-based machine-learning prediction of cetane number using quantitative structure–property relationship

The physicochemical properties of liquid alternative fuels are important but difficult to measure/predict, especially when complex surrogate fuels are concerned. In the present work, machine learning is used to develop quantitative structure–property relationship models. The fuel chemical structure is represented by molecular descriptors, allowing the linking of important features of the fuel composition and key properties of fuel utilization. Feature selection is employed to select the most relevant features that describe the chemical structure of the fuel and several machine learning algorithms are tested to construct interpretable models. The effectiveness of the methodology is demonstrated through the development of accurate and interpretable predictive models for cetane numbers, with a focus on understanding the link between molecular structure and fuel properties. In this context, matrix-based descriptors and descriptors related to the number of atoms in the molecule are directly linked with the cetane number of hydrocarbons. Furthermore, the results showed that molecular connectivity indices play a role in the cetane number for aromatic molecules. Also, the methodology is extended to predict the cetane number of ester and ether molecules, leveraging the design of alternative fuels towards fully sustainable fuel utilization.

Fast Pyrolysis of Municipal Green Waste in an Auger Reactor: Effects of Residence Time and Particle Size on the Yield and Characteristics of Produced Oil

The development of renewable sources for energy production has assumed a vital role in recent years, particularly with regard to the preservation of energy supplies and the environment. In this regard, municipal green waste (MGW) can be a potential renewable energy source if it is integrated with emerging technology, like pyrolysis. Therefore, this study aimed at investigating the effect of residence time and particle size on the yield and composition of oil derived from MGW using fast pyrolysis in an auger reactor. The residence time and particle size were varied from 1 min to 4 min and 1 mm to 10 mm, respectively, while keeping the temperature constant at 500 °C. At a residence time of 3 min, a 2 mm particle size provided the highest bio-oil yield (39.86%). At this experimental setting, biochar yield of 27.16% and syngas yield of 32.98% were obtained. The characterization of produced bio-oil revealed that a total of nine functional groups were present in the bio-oil. The phenols were highest in amount, followed by aromatics and ketones. The increase in residence time decreased the amount of acidic compounds present in the bio-oil. The water content was decreased by ~11% and the calorific value was increased by ~6% with the increase in particle size from 1 mm to 10 mm. Other properties, such as viscosity, density, cetane number, and flash point, did not change significantly with the change in experimental conditions. With a calorific value of 25+ MJ/kg, although the bio-oil produced from MGW can be used for heating (such as in boilers and furnaces), the use of MGW bio-oil in engines requires appropriate upgrading through procedures like hydrodeoxygenation, catalytic cracking, esterification, etc.

Investigation of bionano additives in red algae Cyanidioschyzon merolae ultrasonified MgO/MWCNT catalyzed biodiesel in optimized engine performance

Renewable energy research is burgeoning with the anticipation of finding neat liquid fuel. Ultra sonification assisted biodiesel was derived from red algae Cyanidioschyzon merolae, with biodiesel yield of 98.9%. The results of GC MS of the prepared biodiesel showed higher concentration of methyl palmitate, methyl oleate, and stearate. This composition is appreciable, as this plays significance in desirable pour & cloud point properties. NMR spectrum revealed the ester linkages, presence of olefins, and α methyl position in olefins. Mixture of 30 wt% of biodiesel in diesel exhibited work efficiency, and also exhibited low pour point and, lower viscosity values. CeO2 and Fe2O3 nano particles were bio reduced, and were added as nano additive in biodiesel. 1:1 ratio of CeO2 and Fe2O3 added to biodiesel maximised the combustion ability of fuel owing to the oxygen storage capacity of CeO2. Further, this combination produced a satisfactory calorific value. Imbalanced ratios disrupted the catalytic and oxygen storage effects, reduced the overall energy release and calorific value of the biodiesel blend. Pour point and cetane number value of biodiesel blend ultrasonifacted with 1:1 mass ratio of Fe2O3 and CeO2 was observed to be around −7 °C and 53 °C respectively, and was better than other compositions. 1:1 mass ratio of NPS blended with 30 wt% BD in diesel showed tremendous increase in brake thermal efficiency, torque, and power. HC, NOX, and SOX emissions were reduced by 42.8%, 19.3%, and 57% respectively with 1:1 Fe2O3 and CeO2 mixed biodiesel blend. CeO2 favourably improved the oxygen storage capacity of the fuel, whereas Fe2O3 showed decrease in formation of gums and sediments in biodiesel.

Experimental investigation on diesel engine performance, combustion, and emissions characteristics with Tucuma and Ungurahui biodiesel blends

The study conducted an experimental investigation of diesel engine performance, emissions, and combustion characteristics using Tucuma and Ungurahui biodiesel blends. Higher yield (greater than 99.4%), lower viscosity than diesel, and higher cetane number of these fuels have motivated a comprehensive investigation of the effect of these fuels on diesel engines. Four blends were tested in the engine by keeping diesel as the benchmarking fuel. The engine was operated at full load conditions, and the results were investigated with respect to brake power (BP). Results indicate that biodiesel blends showed similar combustion behaviour to that of diesel. Next to diesel, TB10 and UB10 showed better brake thermal efficiency (BTE) and lower brake-specific fuel consumption (BSFC). Higher peak pressures and heat release rates (HRR) are observed for the TB10 compared to the diesel operation. Moreover, prolonged combustion was observed for the four biodiesel blends during the diffusion and late combustion phasing. With the increase in BP, slightly higher HC emissions are observed for all the blends except for TB10 compared to diesel. Similarly, a slight increase in CO emissions is also observed for all the blends at higher BP. Higher acid values of both fuels are the likely cause of increased HC and CO emissions at higher BP. NOx emissions are slightly higher for both fuels, among these UB10 has shown lower NOx than other blends. The study concludes that TB10 has demonstrated better performance (near diesel) and combustion rates (better than diesel); however, emissions like CO and NOx are slightly higher than others. The study recommends blending TB10 and UB10 with the alcohols, ethers, and nanoparticles as they can reduce NOx and CO emissions.

Experimental investigation of ternary blends on performance, and emission behaviors of a modified low-heat rejection CI engine

This study investigated the performance, combustion, and emissions of a modified low heat rejection (LHR) diesel engine fueled with a blend of 90 % coconut waste cooking oil (CWCO) biodiesel and 10 % diethyl ether (DEE). The engine combustion chamber components were coated with 300 μm lanthanum-doped partially stabilized zirconia for thermal insulation. Engine testing was performed at varied loads from 0 to 100 % using an eddy current dynamometer. Exhaust emissions, including hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and smoke were measured. Compared to conventional diesel, the CWCO-DEE blend showed a 3 % higher brake thermal efficiency of 33.4 % and 2.42 % lower brake-specific fuel consumption at full load. HC, CO, and smoke emissions decreased by 18 % (39 ppm), 11 %, and 19 % at higher loads with the blend. However, NOx emissions increased slightly by 21.2 %. The DEE compensated for CWCO's lower cetane number and viscosity, while the LHR coating enhanced combustion by providing thermal insulation, raising exhaust gas temperatures by 13 %. The improved efficiency and reduced emissions demonstrate the potential of optimized biodiesel-additive blends in conjunction with LHR engine modifications to sustainably utilize inexpensive waste cooking oil feedstocks as renewable diesel replacements. However, further optimization of blend compositions, additives, and coatings is needed to balance performance benefits against possible NOx increases. This study highlights a promising combined approach leveraging engine design and fuel advancements.

Biorefinery of waste activated sludge: Nutrient recovery and microbial lipid production by Yarrowia lipolytica

The rising generation of waste activated sludge (WAS) demands a fundamental shift towards resource reuse and recovery. The conventional methodologies used to manage this by-product derived from wastewater treatment plants are increasingly constrained due to stringent regulatory measures aimed at mitigating its adverse impacts on the environment and public health. Therefore, this work evaluated a promising strategy for the efficient management of WAS, transforming it into a valuable renewable source to produce high-value-added compounds, such as lipids and a slow-release fertilizer (struvite). Wet oxidation (WO) was identified as a suitable technique for solubilising WAS while generating short-chain fatty acids (primarily acetic acid). It was found that conducting WO at 200 °C for 120 min resulted in a 65% reduction of the total suspended solids (TSS) content and 87% of the volatile suspended solids (VSS) content. Additionally, under these conditions, 4440 ± 105 mg/L and 593 ± 21 mg/L of acetic and propionic acid were obtained, respectively, which were assimilated by Yarrowia lipolytica to produce biolipids. Furthermore, the rupture of WAS flocs also led to the solubilisation of 980 ± 8 mg/L of ammonium. During the struvite precipitation stage, a NH4:PO4:Mg ratio of 1:1.5:1.5 was found to be the most effective for removing soluble ammonium (97.4 ± 0.8%), resulting in a high-purity struvite formation, and enhancing the carbon/nitrogen (C/N) ratio of the oxidised WAS from 3 to 105. This improvement in the C/N ratio raised the lipid content from 36 ± 1% to 49 ± 1% during the cultivation of Y. lipolytica. The application of the sequencing batch culture strategy further increased lipid content to 59 ± 1%, with 6.0 ± 0.3 g/L as the final concentration after the fifth cycle. The lipids produced, mainly monounsaturated fatty acids with 40% of oleic acid, offer potential as biodiesel feedstock. This lipid composition led to biodiesel properties, including cetane number, iodine value, kinematic viscosity and density that met international standards. Therefore, this research presents a promising alternative not only for WAS management but also for harnessing valuable resources, thereby establishing a basis for large-scale studies.

Machine Learning for Characterizing Biofuels Based on Femtosecond Laser Ionization Mass Spectrometry.

A sample mixture of fatty acid methyl esters (FAMEs) was measured by femtosecond laser ionization mass spectrometry (fsLIMS) using the fifth (206 nm) and fourth (257 nm) harmonic emissions of an ytterbium (Yb) laser (1030 nm). Molecular ions were observed as the major signals in this technique, providing valuable information concerning the molecular weight and the number of double bonds in the molecule. The mass spectral data were then used as explanatory variables in machine learning based on artificial intelligence (AI) to correlate with objective variables such as the cetane number, kinematic viscosity, specific gravity, a higher heating value, an iodine value, flash point, oxidative stability index, and a cloud point measured for reference biofuel samples containing various FAMEs. The properties of biofuels, i.e., the objective variables, were evaluated from the mass spectral data obtained for unknown samples. The errors in the evaluation were a few percent when the distribution of the FAMEs in the unknown biofuel sample was similar to those of the biofuels used for machine learning. As demonstrated herein, the present approach, involving a combination of fsLIMS and AI, has the potential for use in evaluating the properties of a biofuel and then in solving of environmental issues associated with global warming.

Performance characteristics of marine diatoms Cylindrotheca sp. and Trieres chinensis under nutrient limitation and their potency as feedstock for biodiesel production

Microalgae-derived biodiesel is commonly studied and recently gained attention as a possible substitute feedstock for production of biodiesel. In this study, the potential of marine diatoms, Cylindrotheca sp. (FPU 0031) and T. chinensis (FPU 0030), for production of biodiesel was evaluated by investigating the effect of nutrient limitation (100, 75, 50, and 25 % Roschin medium) on growth behavior response, lipid productivity, and FAME profiles of the diatom strains. The total lipid yield increased under nutrient-limited culture condition. When the concentration of the nutrient was restricted to 50 %, the average lipid yield of Cylindrotheca sp. and T. chinensis were 19.32 and 21.72 % with lipid productivity of 73.46 and 68.19 mg L−1 day−1, respectively. Nutrient limitation resulted in a decrease in biomass yield and an increase in the lipid yield of the diatom strains. The properties of biodiesel generated by the two diatoms were assessed based on FAME profiles using empirical equations. Results showed that Cylindrotheca sp. and T. chinensis conforms to the biodiesel standards specifications set by EN 14214 and ASTM D6751. The predicted properties of biodiesel observed for Cylindrotheca sp. and T. chinensis were both ideal, e.g. good cold filter plugging points (−6.94 °C and − 2.16 °C), cetane numbers (65.57 and 75.29), cloud points (1.81 °C and 7.75 °C), pour points (1.60 °C and − 4.86 °C), and low kinematic viscosities (2.89 and 2.16 mm2 s−1), respectively. Thus, suggesting the potential use of these diatoms as feedstock for producing biodiesel with high-grade fuel characteristics.

Surface functionalization of SBA-15 with organosilane for the preparation of bimetallic Ni-Co/SBA-15 catalyst: An innovative approach to convert waste cooking oil into advanced biofuel energy

This research investigates the utilization of bimetallic nickel-cobalt supported SBA-15-silane catalysts for the production of green diesel from waste cooking oil (WCO), aiming at sustainable energy solutions. The catalysts underwent surface-functionalization with three distinct silane types: mercaptosilane (-SH), aminosilane (-NH2), and phenylsilane (-Ph). Notably, the incorporation of -NH2 silane in the fabrication of bimetallic NiCo/SBA-15-NH2 catalyst led to significant improvements in catalyst properties. Specifically, enhancements were observed in pore characteristics, with a surface area of 424 m2/g and a pore size of 4.8 nm, along with an increase in acidity to 5038.91 μmol/g. This rise in acidity is attributed to the presence of amino groups (-NH2), which foster stronger electrostatic interactions between the support and nickel-cobalt particles, subsequently affecting the particle size of Ni-Co (as confirmed by HRTEM analysis). Parametric studies unveiled the superior performance of the NiCo/SBA-15-NH2 catalyst, demonstrating a notable hydrocarbon yield of 80 % and diesel selectivity of 90 % at a reaction temperature of 300 °C, with sustained optimal performance for up to 6 h of reaction time. Furthermore, the blended green diesel (G2.5 & G5) derived from this process exhibited favorable fuel properties including lower kinematic viscosity, higher cetane number, and lower pour point in comparison to commercial petrol-diesel. These findings underscore the significant potential of silane in catalyst preparation for the conversion of WCO into biofuel energy, thereby highlighting a promising avenue for sustainable energy production and waste management.

Hybrid CaO/ZnFe2O4 Modified with Al2O3 as a Green Catalyst for Biodiesel Production from Waste Cooking Oil

In this work, biodiesel was produced from waste cooking oil (WCO) via a green catalyst of CaO-ZnFe2O4 modified Al2O3. The catalyst was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), SEM-mapping, Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM) analyses. The catalyst performance was studied in the transesterification reaction of WCO conversion to biodiesel. The catalytic activity increased with the combination of nanoparticles effect and support catalysts obtained biodiesel yield of nano-Al2O3, nano-CaO, ZnFe2O4, CaO-ZnFe2O4, and CaO-ZnFe2O4/Al2O3 is 36.86%, 67.16%, 74.83%, 86.54%, and 93.41%, respectively. The best biodiesel yield was 93.41% with a mass ratio of Al2O3 to CaO-ZnFe2O4 (2:1). The physicochemical properties (acid number, density, kinematic viscosity, flash point, and cetane number) of biodiesel under the optimal conditions agreed with the ASTM standard. These results show that the developed nanocomposite has great potential to reduce biodiesel production costs because derived from WCO. In conclusion, CaO-ZnFe2O4 modified Al2O3 as a catalyst has a high potential for biodiesel production on a large scale.

A comparative study of diesel engine fueled by Jatropha and Castor biodiesel: Performance, emissions, and sustainability assessment

The increasing scarcity of fossil fuels and environmental concerns have driven the search for sustainable alternatives, such as biodiesel. This study aims to evaluate the performance, emissions, and sustainability of biodiesel derived from Jatropha and Castor seeds when used in diesel engines. Biodiesel production was achieved through the transesterification process, addressing atomization challenges, and enhancing combustion efficiency. The research compared various blends of biodiesel and conventional diesel fuel (B20, B40, and B60) across different engine loads, from no load to full load. Key findings revealed that biodiesel blends exhibited comparable properties to conventional diesel. Jatropha biodiesel showed superior performance and lower emissions compared to Castor biodiesel. The B20 blend consistently demonstrated the best performance and reduced emissions across all engine loads. Specifically, biodiesel resulted in lower brake thermal efficiency (BTE), carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC), and smoke emissions compared to conventional diesel, but higher exhaust gas temperature (EGT), brake-specific fuel consumption (BSFC), and nitrogen oxide (NOx) emissions. The increase in NOx emissions was linked to higher EGT, while other emissions were influenced by the biodiesel’s viscosity and cetane number. The study concluded that the B20 blend of Jatropha and Castor biodiesel offers a viable alternative to conventional diesel, reducing CO2 and CO emissions by 22–10 % and increasing NOx emissions by 8 %. These results suggest significant potential for biodiesel to contribute to sustainable transportation, highlighting the importance of optimizing biodiesel blends for improved engine performance and lower environmental impact. These findings highlight the promising potential of Jatropha and Castor biodiesel as substitutes for diesel fuel, indicating advancements in fuel technology.

Numerical investigation of equivalence ratio effects on Flex-Fuel mixing controlled combustion enabled by prechamber ignition

There is interest in adapting renewable and low-carbon intensity fuels to heavy-duty engines to help displace criteria and greenhouse gas emissions associated with diesel combustion. Low-carbon fuels have inherently low cetane numbers and thus pose a significant challenge when considering direct substitution in diesel combustion systems. Use of an actively fueled prechamber as an ignition source to initiate mixing-controlled combustion (PC-MCC) of low-cetane fuels is becoming an attractive combustion mode to alleviate the identified reactivity deficit. This work focuses on the utilization of an active prechamber to facilitate diesel-like combustion of bioethanol-gasoline fuel blends in a heavy-duty engine. Recent results in this emerging technology suggest that ignition quality is uniquely coupled to prechamber equivalence ratio. In this numerical study, the fundamental implications of prechamber equivalence ratio on the ignition performance of direct injected fuels ranging from E10 to E100 are investigated using CONVERGE. Parametric studies of the prechamber operating strategy were assessed at diesel-like conditions to characterize the performance trends relative to a diesel baseline at the same boundary conditions. Simulation results indicate that PC-MCC is flex-fuel capable and achieves diesel-like ignition qualities and combustion processes for all fuels considered under stoichiometric and rich prechamber conditions. To characterize the equivalence ratio trends observed, a novel inflow boundary modeling technique was utilized to prescribe turbulent jets in place of the prechamber where selective speciation of the jet composition was conducted to isolate the ignition contributions of radical and reacting species in lean, stoichiometric, and rich jets. The inflow boundary modeling suggests that excess fuel and combustion intermediates present in jets produced from stratified and fuel-rich prechamber operation promotes higher jet temperatures and as such are superior ignition sources. Relative to a lean prechamber jet, the peak temperature of a reacting jet from a rich prechamber was up to 600 K hotter at fixed distances from the orifice exit. Radicals also demonstrated an influence on the ignition process, but the combustion mode was identified to be thermally dominant.

Experimental study for the effect of spark ignition on methanol/PODE dual fuel combustion under medium and low loads

Methanol/high reactivity fuel (HRF) dual fuel combustion cannot further extend methanol energy ratio (MER) at medium and low loads. Polyoxymethylene dimethyl ether (PODE) as a biofuel with high cetane number is well suited for HRF. This paper explored the effect of spark ignition (SI) on energy conversion and MER extension for methanol/PODE under medium and low loads. The results show that SI triggers the exothermic processes of SI and dual fuel spark-assisted compression ignition (D-SACI). SI raised MER from 30 %, 40 %, 46 % to 40 %, 60 %, 90 % for brake mean effective pressure (BMEP) of 0.2, 0.4, 0.6 MPa, respectively. SI and D-SACI combustion can partially or completely replace premixed compression ignition (CI). Diffusion combustion and one or more exothermic processes of SI, D-SACI and premixed CI make up two-stage or three-stage exotherm. D-SACI is easily triggered when spark timing approaches PODE injection timing, otherwise, SI exotherm is easily triggered; at BMEP of 0.6 MPa, the exothermic energy of premixed CI is gradually converted into the exothermic energy of D-SACI and SI as MER increases. By optimizing, maximum brake thermal efficiency for BMEP of 0.4 and 0.6 MPa are 37.75 % and 42.82 %, respectively, corresponding to the MER of 50 % and 80 %, respectively.

Impact of fuel injection parameters associated with partially hydrogenated Ceiba pentandra biodiesel blend on CI engine characteristics

Multiple studies have shown that biodiesel blends significantly cut exhaust emissions. However, the most significant challenge was the rising emission of oxides of nitrogen (NOx). The authors' prior research showed that a Ceiba pentandra biodiesel blend (B20) with a higher IP of 260 bar and an advanced IT of 27° BTDC as an optimal Fuel injection parameter (FIP) resulted in superior combustion and reduced emissions except NOx. To further enhance engine performance, fuel reformulation strategies have been implemented together with FIP modification. This research intends to examine the impact of FIP combined with blending of partially hydrogenated biodiesel (HB) on engine characteristics. As a result of partial hydrogenation, the degree of unsaturation decreased by 60%, and the Cetane Number (CN) increased by 22%. Higher BTE (8%), TFC (3.4%), CP (13%), HRR (5%) and lower HC (12%), and CO (5.5%) emissions can be achieved when HB20 was combined with optimal FIP. Superior outcomes were seen with hydrogenated blend (HB20) than with normal B20, with a reduction in NOx emissions by 6.7% without significantly impacting the smoke emission trade-off. Thus, cutting-edge fuel reformulation approaches make way for eco-friendly engineering.