Diesel Combustion Research Articles

Kinetics of biodesulfurization of South African diesel using Pseudomonas aeruginosa

As a result of several environmental and health challenges associated with the emission of SOx during the direct combustion of diesel, stringent regulations have been issued by the Environmental Protection Agency (EPA) and the South African government to all refineries in South Africa. Therefore, the development of an effective, affordable, and less energy-intensive technique is therefore urgently required. In this recent study, real South African diesel (obtained after HDS, 120 ppm) was degraded by resting cells of Pseudomonas aeruginosa in a batch experiment. About 5 mL of diesel was measured into a 250 mL Erlenmeyer flask with 5 mL of resting cell in glycerol/NaCl (1:1) and 20 mL of Basal Salt Media (BSM). The mixture was incubated for 8 h, at 37 °C, and agitated at 130 rpm, with an initial hydrodesulfurized diesel concentration of 120 mg/L and cell mass of 1.2 gDCW/L. High-Liquid Chromatography and Gas/Mass (GC/MS) chromatography were used to determine the initial and final concentrations of the synthetic and real diesel samples. Findings showed about 70.54 % removal of DBT in 120 ppm desulfurized diesel. Meanwhile, Pseudomonas aeruginosa selectively converted sulfur atoms in DBT compound to 2-HBP. Michaelis-Menten for modeling the growth of the bacteria fitted well into the experimental data. Similarly, First-order kinetic fitted and described well the behavior of the bacteria for degradation of DBT in synthetic and real diesel samples. The findings of this investigation indicated that biodesulfurization would be a more effective method to complement the hydrodesulfurization (HDS) technique as opposed to the primary methods for desulfurizing organo-sulfur compounds in diesel oil. This will assist the refineries to meet up with the stringent regulation to minimize the emission of sulfur compounds, which cause environmental pollution and health problems in South Africa and all over the world.

Thermal characterization of a high-temperature industrial bread-baking oven: A comprehensive experimental and numerical study

This study presents a complete experimental campaign and the first three-dimensional numerical model developed for a high-temperature bread-baking oven. A typical baking tunnel oven prototype is designed and constructed for the study. The prototype has appropriate temperature sensors to investigate temperature profiles at several points inside the baking chamber. A specific device is developed to measure the heat flux received by bread during baking, showing values ranging between 6.6 and 29.3 kW/m2. Computational fluid dynamic software models the non-premixed combustion of diesel fuel occurring at the burner and the airflow characteristics inside the baking chamber. Numerical results show the heterogeneity of temperatures (450–1000 °C) inside the tunnel oven and agree with the experimentally measured values (maximal variation of 9 %) also shows complex airflow dynamics and the existence of multiple velocity zones. The model is applied to the specific case of Lebanese bread baking. An energy efficiency analysis of the oven reveals an efficiency range of around 16 %. This foundational work sets the stage for future research and optimization of oven design, energy recovery systems, and bread-baking processes. Also, the insights gained from this study will be integral in developing future numerical models for flatbread baking coupled with large deformation.

Effects of diesel-biodiesel fuel blends doped with zinc oxide nanoparticles on performance and combustion attributes of a diesel engine

To improve the fuel properties and enhance the overall characteristics of a diesel engine, the current work assesses the performance and combustion attributes of a diesel engine fueled by different blends of diesel, second generation biodiesel, and zinc oxide (ZnO) nanoparticles. The biodiesel was prepared using the transesterification of waste cooking vegetable oil. Zinc oxide nanoparticles were dispersed in diesel and biodiesel fuel blends at one dosage level of 50 ppm using ultrasonication process to prevent their agglomeration in the base liquid. The experiments were performed at different engine speeds (1700, 2000, 2300, 2600, 2900) RPM and full load operating conditions. The experimental results revealed that the addition of ZnO compensated for the poor combustion characteristic of biodiesel and hence promoted diesel engine performance and combustion attributes. The engine torque improved by 6.74, 4.9 and 3.69% while the BSFC reduced by 5.6, 6.44 and 2.5% for B0ZnO, B20ZnO and B40ZnO fuel blends compared to B0, B20 and B40 respectively at 2300 RPM. In addition, the engine heat release rate, ignition delay period and in-cylinder pressure were promoted. ZnO nanoparticles additives could be an effective approach for improving the combustion and performance characteristics in diesel engine applications.

Utilization of structural high entropy alloy for CO oxidation to CO2

The nanoengineered high entropy alloy (HEAs) catalysts have attracted the attention of the scientific community due to their exceptional characteristics, wide range of compositional tunability and the utilization of low-cost transition metals. During various electrochemical reactions, the oxidation of carbon-mono-oxide (CO) is an intermediate and it acts as a poison to reduce the efficiency of the reactions. Also, CO is a poisonous gas which is generated during gasoline and diesel combustion in the automobiles. A nanocrystalline HEA catalyst (CoFeNiGaZn) is prepared by easily scalable casting-cum-comminution method, providing pristine catalyst surfaces. It is capable of catalyzing the CO-oxidation to CO2 with high conversion efficiency (∼98%). Density functional theory calculations show that the high activity of the HEA can be attributed to the presence of a considerable amount of filled states of dxz and dyz orbital near the Fermi level for Ni atoms over the surface. Due to the favorable transfer of electrons from this orbitals to the lowest unoccupied molecular orbital of O2 and adsorption of gaseous CO directly on O∗ to form CO2, the endothermicity of the rate-determining step is 0.43 eV in the Eley-Rideal pathway.

Improvement of diesel combustion with suppression of mutual fuel spray flame interactions with staggered nozzle hole arrangement and a spatially divided combustion chamber

A combination of a fuel injector with staggered nozzle hole arrangement with a combustion chamber divided into upper and lower layers by placing a lip at the middle of the side wall is proposed to improve diesel combustion with suppression of interactions among fuel spray flames. The fuel injector has twelve alternately arranged spray holes ( ϕ0.09 mm), staggered at two injection angles, 79° and 55° from the central axis of the injector. Two ordinary injectors with eight ( ϕ0.113 mm) and twelve ( ϕ0.092 mm) holes with an injection angle of 78° from the central axis with a conventional re-entrant combustion chamber were also examined as references. The experimental results showed that the improvements in thermal efficiencies and the reduction in smoke emissions can be established over a wide IMEP range with the proposed combination of the staggered nozzle hole injector and the divided combustion chamber. The exhaust loss is reduced with the combination of the injector and the combustion chamber while the cooling loss increases slightly. The rate of heat release from the combination of the injector and the combustion chamber has a more active main combustion and smaller afterburning than conventional systems. The three-dimensional CFD simulations showed that the combination of the injector and the combustion chamber can efficiently suppress the interactions among fuel spray flames at the combustion chamber wall after the impingement of fuel spray flames and also suitably distribute the fuel mixture, resulting in reductions in the afterburning and the smoke emissions. The slight increase in cooling loss with the proposed combination may be due to the increase in contact area of hot burned gas on the cylinder head; further improvements in thermal efficiency can be expected with optimization of the design factors related to the fuel injection and the combustion chamber configuration.

Optical diagnostic study of internal and external EGR combined with oxygenated fuels of n-butanol, PODE3 and DMC to optimize the combustion process of FT synthetic diesel

With the introduction of carbon neutrality target, Fischer-Tropsch (FT) synthetic fuels are coming back into the limelight as a kind of carbon–neutral fuel. However, the mismatch between the overly high cetane number (CN) and the relatively low vaporability of FT synthetic diesel is unfavorable to the soot emission control, which will make it difficult to meet more stringent fuel consumption and emission regulations in future applications. To investigate the potential of oxygenated fuels combined with different exhaust gas recirculation (EGR) introduction schemes to achieve high-efficiency and clean combustion of FT synthetic diesel, an optical diagnostic study was carried out based on high-speed photography and the two-color method. The results show that all three kinds of oxygenated fuels could suppress soot emissions via self-carrying oxygen and adjusting the physicochemical properties of the fuel blend. Compared with the combustion characteristics of FT synthetic diesel, the flame area and luminosity of oxygenated blends are reduced, and the in-cylinder temperature and soot KL factor are lowered. Among them, n-butanol exhibits a greater capability of soot control compared to polyoxymethylene dimethyl ethers (PODE3) and dimethyl carbonate (DMC). In addition, introducing internal and external EGR to the engine fueled by n-butanol/FT synthetic diesel blend shows that with the increase of EGR rate, the external EGR exhibits a gradually stronger inhibiting effect on the heat release process and soot KL factor, while the internal EGR exhibits an inhibiting and then promoting effect. Moreover, the high ratio internal EGR shortens the ignition delay (ID) significantly due to the strong heating effect, which is unfavorable to the control of soot emission. The combination of oxygenated fuels and internal/external EGR could effectively optimize the combustion process of FT synthetic diesel and inhibit soot generation, but the EGR rate needs to be controlled within a proper range.

Effect of injection parameters on the hydrogen enriched dual-fuel CRDI diesel engine

ABSTRACT To maximize the performance of the diesel engine run with alternative renewable fuels, operational parameters such as injection time (IT) and injection pressure (IP) must be fine-tuned. Meanwhile, hydrogen has come out as a one of the best alternative fuel for dual-fuel mode of operation, since it minimizes the drawback that use of biodiesel alone possesses like low calorific value, high viscosity etc. Based on the above findings, the objective of the current study is set as “to evaluate the impact of varying injection parameters on the engine characteristics of hydrogen-enriched palm fueled CRDI diesel engine.” In this research work, a hydrogen-enriched (7 lpm and 10 lpm) palm biodiesel blend (P20) with diesel fuel was used to examine how changing injection pressure (IP) and injection time (IT) affected CRDI diesel engine performance, combustion, and emission characteristics. Three different IPs (240 bar, 420 bar, and 600 bar) and ITs (23°CA bTDC, 25°CA bTDC, and 27°CA bTDC) are used at a steady speed of 1500 rpm under full load circumstances. The results showed a maximum BTE of 31.09% for P20 + 10 H2 at 25°CA bTDC IT and 600 bar IP. Better fuel atomization is responsible for the improvement in BTE (17.94%) and BSFC (15.15%) with increased IP (600 bar). Advancement in IT (25°CA bTDC) leads to superior performance in terms of HC (32%) and CO (8.33%) emissions reduction for P20 + 10 H2 because more time is available for optimal air-fuel mixing. However, NOX emission increases significantly because of the rise in temperature within the cylinder with hydrogen enrichment. This can be attributed to the high calorific value of hydrogen which is almost three times to that of diesel. A maximum increase in NOX emission of 45.65% is obtained for P20 + 10 H2 w.r.t. diesel. With an increase in IP, ICP and HRR improve by 28.04% and 22.70%, respectively, due to improved fuel atomization, resulting in the greatest amount of fuel being burned during the pre-mixed combustion stage. It can be concluded that the 25°CA bTDC IT and 600 bar IP is the optimum condition when the engine performs at its peak.

Toxicity assessment of CeO₂ and CuO nanoparticles at the air-liquid interface using bioinspired condensational particle growth

CeO2 and CuO nanoparticles (NPs) are used as additives in petrodiesel to enhance engine performance leading to reduced diesel combustion emissions. Despite their benefits, the additive application poses human health concerns by releasing inhalable NPs into the ambient air. In this study, a bioinspired lung cell exposure system, Dosimetric Aerosol in Vitro Inhalation Device (DAVID), was employed for evaluating the toxicity of aerosolized CeO2 and CuO NPs with a short duration of exposure (≤10 min vs. hours in other systems) and without exerting toxicity from non-NP factors. Human epithelial A549 lung cells were cultured and maintained within DAVID at the air-liquid interface (ALI), onto which aerosolized NPs were deposited, and experiments in submerged cells were used for comparison. Exposure of the cells to the CeO2 NPs did not result in detectable IL-8 release, nor did it produce a significant reduction in cell viability based on lactate dehydrogenase (LDH) assay, with a marginal decrease (10%) at the dose of 388 μg/cm2 (273 cm2/cm2). In contrast, exposure to CuO NPs resulted in a concentration dependent reduction in LDH release based on LDH leakage, with 38% reduction in viability at the highest dose of 52 μg/cm2 (28.3 cm2/cm2). Cells exposed to CuO NPs resulted in a dose dependent cellular membrane toxicity and expressed IL-8 secretion at a global dose five times lower than cells exposed under submerged conditions. However, when comparing the ALI results at the local cellular dose of CuO NPs to the submerged results, the IL-8 secretion was similar. In this study, we demonstrated DAVID as a new exposure tool that helps evaluate aerosol toxicity in simulated lung environment. Our results also highlight the necessity in choosing the right assay endpoints for the given exposure scenario, e.g., LDH for ALI and Deep Blue for submerged conditions for cell viability.

Effect of CO2 and its concentration variation on the ignition and combustion of diesel surrogate fuel: Optical experiments and numerical simulations

To investigate the influence of CO2 on diesel ignition and combustion, an experimental setup comprising a constant volume combustion chamber with optical channels was constructed. High-speed direct photography was employed to capture flame propagation images during fuel ignition and combustion under different CO2/O2 atmospheres. Additionally, large eddy simulation was conducted to model diesel combustion characterized by CO2/O2 environment. The theoretical calculations were then compared with experimental results, focusing on flame natural luminosity, flame structure, flame field, and heat release analysis. The results indicate that the flame structure in a CO2/O2 atmosphere consists of a diffusion flame surrounding a premixed flame, characterized by elevated levels of CO and a smaller amount of C2 radicals at the flame front. The O2 concentration ranged from 21% to 57%, resulting in a flame morphology with thin strips, intensified flame edge instability, and increased natural luminosity. The inhibitory effect of CO2 concentration within the range of 35%–50% counteracted the promoting effect of O2 concentration within the range of 29%–44%. Consequently, the chemical impact of CO2 plays a crucial role in combustion.

Impact of Biofuel Blending on Hydrocarbon Speciation and Particulate Matter from a Medium-Duty Multimode Combustion Strategy

The U.S. Department of Energy’s Co-Optima initiative simultaneous focused on diversifying fuel sources, improving efficiency, and reducing emissions through using novel combustion strategies and sustainable fuel blends. For medium-duty/heavy-duty diesel engines, research in this area has led to the development of a multimode strategy that uses premixed charge compression ignition (PCCI) at low loads and conventional diesel combustion (CDC) at mid–high loads. The aim of this study was to understand how emissions were impacted when using PCCI instead of CDC at low loads and switching to an oxygenated biofuel blend. It provides a detailed speciation of the hydrocarbon (HC) and particulate matter (PM) emissions from a multimode medium-duty engine operating at low loads in PCCI and CDC modes and high loads in CDC. The effect of the oxygenated biofuel blend on emissions was studied at all three mode–load conditions using #2 ULSD and a bio-derived fuel (25% hexyl hexanoate (HHN)) blended in #2 ULSD. The PCCI mode effectively decreased NOx, total HC, and PM/PN emissions, with a substantial decrease in larger particles (≥50 nm). A PM/PN reduction was observed at high loads with the 25% HHN fuel. While the total HC emissions were not impacted by fuel type, the detailed HC analysis exposed changes in the HC’s composition.

Analysis of waste cooking oil biodiesel (WCO) synthesis with TiO2 impregnated CaO from waste shells nano-catalyst

The development of clean and renewable energy sources has become crucial due to the rapid rise in crude oil prices, depleting fossil fuel reserves, and increase in environmental pollution caused by various industries. Due to this phenomenon, biodiesel has emerged as a renewable and eco-friendly alternative to conventional diesel fuel because it is non-toxic and biodegradable. WCO is one of the best resources in biodiesel production which has a high potential such as saving ecological systems, improving pollution by clean emissions, preventing food supplies and more economic. However, this WCO cannot be used directly in diesel combustion engines due to their properties are not good as diesel fuel. Thus, it needs to be converted as biodiesel fuel before apply. In the biodiesel synthesis process, the catalyst for instance KOH, NaOH, HCL, H2SO4 etc. plays a significant role to increase their yield but also needs a washing process. Currently, the synthesis of WCO biodiesel using CaO-TiO2 nanoparticles as a catalyst could be an excellent alternative because it eliminates the biodiesel’s washing step and the catalyst can be reused. Hence, the cost of biodiesel production will be reduced. CaO catalyst was produced by using waste cockle and sea snail shells as a cost-effective and environmentally friendly heterogeneous catalyst. In addition, TiO2 impregnated CaO nanoparticles also have been studied through the ultrasonication process for the improvement in thermo-physical properties of catalyst reaction. It showed that the 15:1 ratio is the ideal ratio for the conversion of biodiesel production for both catalysts, which are 94.58% by using CaO catalyst and 98.78% by using CaO-TiO2 catalyst. Furthermore, the optimum average reaction time is 150 min, equivalent to 2.5 h and catalyst loading is 2.3 wt%.

Life Cycle Assessment of Bioenergy Production Using Wood Pellets: A Case Study of Remote Communities in Canada

In remote communities of Canada, diesel is the primary source of electricity and heat. Promoting sustainable and diverse means of heat and power generation is essential to providing reliable and less carbon-intensive energy supply to remote communities. Among renewable energy sources in Canada, biomass is a major source of energy, with wood pellets being a notable contributor. In this study, using wood pellets in a remote community of Canada is investigated using life cycle analysis (LCA). Furthermore, wood pellet combustion is compared with diesel combustion, the most common fossil fuel in these regions. SimaPro (version 8.4.0.0) was used with Ecoinvent 3 as the primary library because of the nature of the feedstock. Harvesting, transportation, sawmill operation, pelletization, and combustion stages are considered in LCA. In doing so, first, life cycle data related to each of these stages are collected with respect to eight impact categories of global warming, ozone depletion, carcinogenic, non-carcinogenic, smog, respiratory effects, acidification, eutrophication, ecotoxicity, and fossil fuel depletion. The results indicate that pelletization and combustion stages have the greatest environmental impact, specifically in terms of non-carcinogenic effects from pelletization and respiratory effects from pellet combustion. Additionally, when comparing wood pellets to diesel, wood pellet combustion exhibits superior performance across various impact categories, particularly in non-carcinogenic effects.

New insights into the carbon chain structure of alcohol on the combustion of diesel surrogates using ReaxFF molecular dynamics simulations

Achieving clean and efficient combustion of diesel fuel is the main trend in the development of diesel engines in the future. Adding oxygen-containing alcohol to diesel fuel is an effective way to improve diesel combustion efficiency and reduce carbon smoke emissions, which is of great significance for reducing the consumption of traditional fossil fuels and reducing environmental pollution. In this work, the reactive molecular dynamics (RMD) simulations are conducted to compare the combustion of diesel without/with various alcohols, focusing on the intermediates and product distribution, oxygen consumption, ignition delay time, initial combustion pathways, and the related kinetics. It can be found that the addition of alcohols can significantly improve the combustion of diesel with the promoting order being n-pentanol > n-butanol > ethanol > cyclopentanol. The longer ignition delay of the diesel/ethanol is related to the lower cetane number of ethanol compared to other alcohols. The promoting combustion effect of alcohols can be attributed to higher reaction rate of their unimolecular bond dissociations and hydrogen abstraction reactions. In addition, the straight-chain alcohols have higher oxygen consumption and perform better in reducing soot than cyclic alcohols with the same number of carbon atoms. A significant decrease in activation energy is observed in the diesel/n-pentanol combustion system compared to the pure diesel combustion based on the RMD Arrhenius parameters from the first-order kinetic analysis. From the RMD simulations on the diesel/n-pentanol with different oxygen concentrations, it can lead to the conclusion that when the oxygen amount in the system reaches stoichiometric combustion, adding more oxygen does not produce a significant promoting effect on the diesel combustion process.

Characterization, at Partial Loads, of the Combustion and Emissions of a Dual-Fuel Engine Burning Diesel and a Lean Gas Surrogate

For decentralized power generation in West Africa, gas from a small biomass gasification unit can be used as the main fuel in a dual-fuel engine with diesel as the pilot fuel. To study the combustion in this type of engine (Lister Petter), experiments were conducted with a surrogate gas composed of liquefied petroleum gas and nitrogen (LPGN2), the energy context of which is similar to that of syngas. The tests were conducted at different loads and for different diesel substitution rates. The combustion analysis showed that the LPGN2 mixture had an overall behaviour similar to neat diesel, while the pressure peaks were lower in dual-fuel mode. The results also indicated a longer ignition delay and a pronounced diffusive combustion phase leading to a lower indicated mean effective pressure with gas. The fuel efficiencies remained low in both mono- and dual-fuel operation. The relative instability of the combustion in dual-fuel mode gave rise to an increase in the coefficient of variation (COVIMEP). Compared to neat diesel, the engine running at low loads in dual-fuel mode showed higher emission levels of CO, a slight reduction of 2.5% of CO2 and a substantial decrease of 73% for nitrogen oxides.

Effect of early intake valve closing, exhaust gas recirculation and split injection on combustion and emissions characteristics of a HDDI diesel engine operating in PCCI combustion mode

Premixed Charge Compression Ignition (PCCI) combustion is an alternative to conventional diffusion-controlled combustion for Mono-nitrogen oxides (NOx) and soot emissions reduction in DI diesel engines. However, bringing the center of combustion (CoC) near top dead center (TDC) to reduce brake specific fuel consumption is challenging. In this study, for two Early Intake Valve Closing (EIVC) profiles of split injection strategy, combustion characteristics and emissions of a heavy-duty direct injection (HDDI) diesel engine are evaluated by CFD simulations. Combustion efficiency, Indicated Specific Fuel Consumption (ISFC), NOx, soot, and carbon monoxide (CO) emissions are evaluated for 40 ˚CA and 80˚CA EIVC timings with respect to the base diesel combustion with 0, 30, 50, and 70% Exhaust Gas Recirculation (EGR) rates at 3 bar Brake Mean Effective Pressure (BMEP).CFD simulations reveal that EIVC strategy can displace the CoC towards TDC up to 5–10 ˚CA depending on the EGR rate. Moreover, up to 30% NOx reduction can be achieved in EIVC cases. In 70% EGR case, lower ISFC and near zero NOx emissions can be obtained compared to conventional diesel combustion due to CoC being closer to TDC. However, the EIVC strategy with EGR increases CO emissions due to incomplete combustion of a lower air/fuel ratio mixture.

High-efficiency combustion of gasoline compression ignition (GCI) mode with medium-pressure injection of low-octane gasoline under wide engine load conditions

Gasoline Compression Ignition (GCI) mode with medium injection pressure has the potential to achieve high engine efficiency while keeping costs low. In this study, the combustion and emission characteristics of GCI mode with medium-pressure injection of low-octane gasoline were studied and compared to conventional diesel combustion (CDC) under wide engine loads. The results showed that under low to medium loads, GCI mode had improved particulate emissions and indicated thermal efficiency (ITE) compared to CDC mode. However, at high loads, the PM emissions were much higher than CDC mode, and the ITE decreased for IMEP increasing from 10 to 12 bar due to limited injection pressure. To address this, a dual direct injection GCI mode with medium injection pressure was proposed to improve combustion under high loads. With this strategy, NOx emissions were significantly reduced, and ITE was simultaneously improved for IMEP of 10 and 12 bar. Using low octane gasoline and dual direct injection, the ITE of GCI mode can reach or exceed 50% for IMEP from 4 to 12 bar. Compared to gasoline with a research octane number (RON) of 83, gasoline with an RON of approximately 72 had higher ITE under most tested conditions and is recommended as the fuel for GCI mode.

Assessment of design and location of an active prechamber igniter to enable mixing-controlled combustion of ethanol in heavy-duty engines

This numerical study focuses on assessing the key design parameters of interest for use of an active prechamber igniter as an ignition assistance device to enable mixing-controlled combustion (MCC) of ethanol (E100) in a heavy-duty Caterpillar C9.3B engine. Computational fluid dynamic (CFD) simulations of a baseline diesel and prechamber retrofitted C9.3B at a gross indicated mean effective pressure (IMEPg) of 5 bar and 1800 rpm are carried out using CONVERGE. In particular, the sizing of the prechamber volume, sizing of total orifice cross sectional area (orifice diameter), and location of the prechamber relative to a centrally mounted common rail direct injector are varied to discern the appropriate operational and design characteristics to achieve robust ignition assistance at the selected conditions. Simulation results indicate that use of an active prechamber igniter with E100 as a standalone fuel source can replicate ignition delays and thermal efficiencies similar to diesel combustion at the same engine boundary conditions, thus not requiring any changes to the engine’s air handling system. Igniter mounting location, orifice sizing, and jet targeting were found to have the strongest influence on ignition assistance with preference toward larger orifice diameters that appropriately located heating contributions in near vicinity to the direct injector.

Ducted Fuel Injection Provides Consistently Lower Soot Emissions in Sweep to Full-Load Conditions

<div>Earlier studies have proven how ducted fuel injection (DFI) substantially reduces soot for low- and mid-load conditions in heavy-duty engines, without significant adverse effects on other emissions. Nevertheless, no comprehensive DFI study exists showing soot reductions at high- and full-load conditions. This study investigated DFI in a single-cylinder, 1.7-L, optical engine from low- to full-load conditions with a low-net-carbon fuel consisting of 80% renewable diesel and 20% biodiesel. Over the tested load range, DFI reduced engine-out soot by 38.1–63.1% compared to conventional diesel combustion (CDC). This soot reduction occurred without significant detrimental effects on other emission types. Thus, DFI reduced the severity of the soot–NO<sub>x</sub> tradeoff at all tested conditions. While DFI delivered considerable soot reductions in the present study, previous DFI studies at low- and mid-load conditions delivered larger soot reductions (>90%) compared to CDC operation at the same conditions. Therefore, the DFI configuration used here has been deemed nonoptimal (in terms of parameters such as the injector-spray and piston geometries), and several improvements are recommended for future studies with high-load DFI. These improvements include employing better spray-duct alignment, a deeper piston bowl with a smaller injector umbrella angle, and a fuel injector that opens and closes faster. The study also suggests future research to make DFI ready for commercialization, such as metal-engine tests to ensure desirable DFI performance over an engine’s complete speed/load map. Overall, this study supports the continued development and commercialization of DFI to meet upcoming emissions regulations for heavy-duty vehicles. Specifically, multicylinder engine experiments and CFD simulations should be utilized to optimize the performance and clarify the full potential of DFI.</div>

Cradle-to-gate life cycle assessment of iodine production from caliche ore in Chile

PurposeIodine and its compounds have several industrial uses, primarily in nutrition and healthcare. So far, no specific LCA data for industrial iodine production are available. The purpose of this study is to provide the first LCA using primary industry data for iodine production from caliche ore in Chile.MethodsThe study is a process-based, attributional LCA and follows the relevant ISO standards 14040/44. Primary data were collected from the world’s main producer representing their production for the years 2019 and 2020. Economic allocation was applied to deal with the by-product sodium nitrate. The impact assessment was performed with a set of CML 2001 indicators.Results and discussionCradle-to-gate total LCIA results per 1000 kg of iodine prill product include a GWP100 of 1.48E+04 kg CO2 eq., an AP of 2.53E+02 kg SO2 eq., a POCP of 1.20E+01 kg C2H4 eq., an EP of 9.60E+00 kg PO43− eq., and an ADP fossil of 2.44E+05 MJ. The main contributor across process steps and for most impact categories is electricity consumption. Other hotspots include diesel combustion, hydrogen peroxide, sulfur, sulfuric acid, kerosene, and sodium hydroxide. A scenario analysis with renewable electricity revealed a reduction potential for all impact categories. As an example, the GWP could be reduced by 33–38%.ConclusionsThis study is the first LCA for iodine production from caliche ore based on primary industry data. The switch to renewable sources was identified as the main improvement potential for the hotspot electricity consumption, with a potential reduction of at least 25% for all impact categories except ODP.

All-round inhibition of soot generation during diesel combustion by oxygenated biomass fuels: A numerical simulation and experimental study

Soot generated from diesel combustion is an important pollutant source in the atmosphere. Meanwhile, oxygenated biomass fuels are potential green alternatives to diesel that suppress soot formation. The purpose of this study is to evaluate the effect of oxygenated biomass fuels (biodiesel and ethanol) on all soot precursors (polycyclic aromatic hydrocarbons (PAHs)) and soot particles during diesel combustion. Kinetic modeling results showed that both biodiesel and ethanol monotonically reduced the concentration of PAHs mainly by inhibiting their production and facilitating their oxidation. Specifically, the C2-C4 content reduced and the O, H, and OH concentrations increased. Ethanol has a more profound inhibitory effect on pyrene than biodiesel, mainly due to the reduction of C2-C4 species and increased production of CO2 and CO. Soot particles generated from the combustion of diesel (D100) and its blends (D0.8B0.2/B0.1D0.8E0.1/D0.8E0.2; D and E represent the volume fractions of biodiesel and ethanol in diesel, respectively) were collected on an in-house premix burner. Soot particles were further characterized using thermogravimetric analysis (TGA), elemental analysis (EA), fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). The activation energy of D100 was found to be significantly higher than that of other soot particle samples. After blending oxygenated biomass fuels, there is an increase in O elements, oxygen-containing functional groups, layer spacing and streak distance inside PAH crystals, and streak curvature in soot particles; however, there is a decrease in C elements, aliphatic functional groups, crystal size and crystal stacking thickness of PAHs, and average stripe length. These changes indicate that oxygenated biomass fuels allow soot particles to exhibit a higher oxidation activity, which reduces the amount of soot generated by diesel combustion.