High Ignition Research Articles

The Synergy Effect of Ignition Energy and Spark Plug Gap on Methane Lean Combustion with Addressing Initial Flame Formation and Cyclic Variation.

Controlling carbon emissions could be a win-win for both the environment and humans, and the use of low-carbon fuels is the key to being carbon-neutral in traffic transportation. Natural gas can achieve low carbon emissions and obtain high efficiency, but the poor lean combustion performance may result in large cycle-by-cycle variations. In this study, the synergy effect of high ignition energy and spark plug gap on methane lean combustion was optically studied under low-load and low-EGR conditions. High-speed direct photography combined with simultaneous pressure acquisition was used to analyze early flame characteristics and engine performance. The results show that high ignition energy can improve the methane engine's combustion stability, especially under high excess air coefficient conditions, and the main reason is that the initial flame formation is improved. However, the promoting effect may become marginal when the ignition energy increases above a critical value. As for the effect of spark plug gap, it varies with the ignition energy, and there exists an optimal spark plug gap for a given ignition energy. In another word, high ignition energy must combine with a large spark plug gap; thus, the promoting effect on combustion stability can be maximized and the lean limit can be extended. The statistical analysis of the flame area shows that the speed of initial flame formation is more important in determining combustion stability. As a result, a large spark plug gap (1.20 mm) can extend the lean limit to 1.4 under high ignition energy conditions. The current study shall give some insights into the spark strategies for natural gas engines.

Numerical Simulation of Ammonia Combustion at Different Hydrogen Peroxide Concentrations

Ammonia (NH3) is a promising carbon-free fuel. However, modifying its high ignition temperature and low flame speed remains challenging. In this study, NH3 combustion was numerically investigated using hydrogen peroxide (H2O2) of different concentrations as the oxidizer to overcome these limitations. Adiabatic, free-propagating laminar burning velocities for NH3/H2O2/H2O mixtures were examined using a detailed chemical model. The maximum flame temperature between equivalence ratios is not considerably different at high concentrations of H2O2 (>80%), because the heat release is dominated by H2O2 decomposition. The equivalence ratio does not significantly affect the flame speed when the H2O2 concentration is less than 50%. The impact of H2O2 on the burning velocity at low concentrations is mainly attributed to the chemical effect. The chemical effect gradually decreases and the thermal effect increases because of the high heat release at high H2O2 concentrations. Moreover, the different concentrations of H2O2 consequently divide the flame into two sections. The first section is dominated by H2O2 reactions and the second by NH3 reactions. However, when the H2O2 concentration is 90 or 100%, flames do not appear in both sections. Finally, a quasilinear relationship between the flame speed and (NH2+OH)max mole fraction is identified.

Novel Ultrafine-Grain Mg-Gd/Nd-Y-Ca Alloys with an Increased Ignition Temperature.

Two novel ignition-resistant magnesium alloys, Mg-2Gd-2Y-1Ca and Mg-2Nd-1Y-1Ca, were prepared in the ultrafine-grain condition by equal channel angular pressing (ECAP). In addition, four commercial alloys-AZ31, AX41, AE42 and WE43-were prepared similarly as a reference. The microstructure, mechanical properties and ignition temperature were thoroughly investigated. Both novel alloys exhibited a mean grain size of ~1 µm and dense distribution of small secondary phase particles. The mechanical strength measured by the tensile deformation test showed that the novel alloys are much stronger (~290 MPa) than all commercial alloys except WE43. However, Ca segregation into the grain boundaries caused a significant decrease in ductility (<6%). The ignition temperature of the novel alloys (~950 °C) was considerably improved by the presence of Gd/Nd, Y and Ca. This study showed that both novel alloys exhibit high strength and high ignition temperature in the ultrafine-grain condition.

Numerical analysis of ammonia HCCI combustion in a free piston engine through trajectory-based combustion control

Ammonia is a promising carbon–neutral fuel, able to power heavy-duty vehicles, non-road machineries and ocean ships with zero CO2 emission. However, practical challenges still exist when applying ammonia in traditional internal combustion engines (ICEs) due to its high ignition energy, slow flame propagation and significant NOx emissions. Free piston engine (FPE) is a flexible alternative to ICE whose piston can move freely without the constraints of crankshaft. Therefore, its piston trajectory can be leveraged as a new control means to facilitate ammonia combustion. In this paper, a numerical analysis investigating ammonia HCCI combustion in FPE was presented. A physical-based model was developed at first, including a unique trajectory synthesizing mechanism and a detailed reaction mechanism of ammonia oxidation. Various asymmetric piston trajectories were then employed into the model and the simulated HCCI combustion were analyzed through six characteristics, namely indicated thermal efficiency, location of peak pressure, exhaust gas temperature, combustion duration, ignition delay, and NOx emissions. This investigation not only determines the best compression ratio (CR = 25) for ammonia ignition, but also shape the optimal piston trajectory (symmetric trajectory with Ω = 0.5) for ammonia HCCI combustion to enhance thermal efficiency and reduce NOx emission simultaneously.

Premixed combustion and emission characteristics of methane diluted with ammonia under F-class gas turbine relevant operating condition

Ammonia has been used on a small scale in other industrial equipment, such as gas turbines, as a carbon-free fuel. However, ammonia fuel suffers disadvantages such as high ignition temperature, low flame velocity and high NOx emissions. Doping with ammonia using a more reactive fuel, such as methane, can solve the above problems. Therefore, under the relevant operating conditions of the gas turbine (T = 723 K, p = 16.5 atm), the effect of ammonia content on the combustion and emission characteristics of laminar premixed methane flames was numerically investigated. This research uses the PREMIX code from ANSYS CHEMKIN-PRO 2020 and Okafor chemical kinetic mechanisms and provides a reference for our subsequent analysis of gas turbine operating conditions. Firstly, the emission data of major pollutants under different ammonia content (XNH3 = 0–1.0) and equivalent ratio (Φ = .6–1.4) were calculated. Then, the laminar premixed flame structure is analyzed under the lean fuel conditions associated with gas turbines (Φ = .6, .8). Finally, the effect of ammonia addition on the chemical reaction path of NO and CO emission was studied. The results show that ammonia/methane mixture fuel is more suitable for combustion at .6 &amp;lt; Φ &amp;lt; .8 under high temperature and pressure. High ammonia content (XNH3 &amp;gt; .6) and low equivalent ratio can reduce NO and CO emissions. The molar fractions of H, O, and OH radicals and flame temperature decreased with the increase in ammonia content. In addition, high temperature and high pressure conditions and ammonia content greatly influence the reaction path of NO and CO production. The increase in pressure resulted in a change in the primary reaction that produced NO. In conclusion, this study guides reducing the emission of NO and CO from lean side of gas turbine plants.

Co-hydrothermal carbonization of polyvinyl chloride and lignocellulose biomasses: Influence of biomass feedstock on fuel properties and combustion behaviors

Co-hydrothermal carbonization (co-HTC) of lignocellulose biomass (LB) and chlorinated waste could produce value-added co-hydrochar while simultaneously removing inorganic metal salts and organic chlorine to the liquid phase. However, there is a lack of understanding of the influence of LB feedstocks on the fuel properties and combustion behaviors of co-hydrochars. Therefore, co-hydrochars derived from co-HTC of pine, bamboo, corncob, wheat stalk, and corn stalk with polyvinyl chloride (PVC) at the mass ratio of 9:1 under 260 °C for 30 min were tested. PVC facilitated the hydrolysis, dehydration, and polymerization of LB compositions (hemicellulose, cellulose, soluble lignin, and insoluble lignin). In turn, these LB compositions could prevent PVC aggregation and promote PVC substitution. Hydrochar fragments could coat the PVC surface and hinder its hydrolysis. Interactions between LB compositions and PVC improved the fuel properties and combustion behaviors of co-hydrochars derived from bamboo, corncob, wheat stalk, and corn stalk while decreasing the fuel properties and combustion behaviors of co-hydrochar derived from pine (HC-PPE). Except for HC-PPE, the fuel ratio (fixed carbon/volatile matter) of co-hydrochars increased to 0.90–1.18 and their HHVs reached approximately 17.5–32.45 MJ/kg without an increased risk of chlorine corrosion. The combustion of co-hydrochars was easier and more stable due to their higher ignition and burnout temperatures and lower activation energies. These findings provide comprehensive knowledge of the LB feedstocks influence on fuel properties and combustion behaviors of co-hydrochars, which would contribute to the cost-effective use of LB and chlorinated wastes.

Large mitigation potential of smoke PM2.5 in the US from human-ignited fires

Increasing fire activity and the associated degradation in air quality in the United States has been indirectly linked to human activity via climate change. In addition, direct attribution of fires to human activities may provide opportunities for near term smoke mitigation by focusing policy, management, and funding efforts on particular ignition sources. We analyze how fires associated with human ignitions (agricultural fires and human-initiated wildfires) impact fire particulate matter under 2.5 µm (PM2.5) concentrations in the contiguous United States (CONUS) from 2003 to 2018. We find that these agricultural and human-initiated wildfires dominate fire PM2.5 in both a high fire and human ignition year (2018) and low fire and human ignition year (2003). Smoke from these human levers also makes meaningful contributions to total PM2.5 (∼5%–10% in 2003 and 2018). Across CONUS, these two human ignition processes account for more than 80% of the population-weighted exposure and premature deaths associated with fire PM2.5. These findings indicate that a large portion of the smoke exposure and impacts in CONUS are from fires ignited by human activities with large mitigation potential that could be the focus of future management choices and policymaking.

Research progress on low-concentration methane oxidation using palladium-based catalysts

There is low concentration (0.05% to 0.5%) of CH4 leakage in marine natural gas engine exhaust. It is difficult to capture and utilize low concentration CH4 because of its stable chemical structure and high ignition temperature. Catalytic oxidation is the main method to remove low concentration CH4 from tail gas. The noble metal palladium (Pd) is the best catalytic material for the complete oxidation of low concentration CH4. In this paper, the main research progress of Pd-based catalysts is reviewed for their low-temperature activity, reliability and development cost. Initially, the impact of Pd particle dimensions and valence distribution, Pd dispersion, carrier identity and strong metal-carrier interaction (SMSI) on the catalyst's methane oxidation activity was elucidated. Then, the mechanism of methane oxidation on the surface of Pdbased catalysts is summarized; In addition, the deactivation mechanisms of Pd-based catalysts, such as high temperature sintering, water poisoning and sulphur poisoning, are described in detail. In conclusion, the major hurdles encountered in achieving full oxidation of methane at low concentrations are outlined, along with the future development direction for methane oxidation catalysts. Additionally, strategies to enhance the performance of Pd-based catalysts are briefly suggested. The modified Text maintains a clear, professional, and concise style with minimal changes.

Experimental investigation of the stability and emission characteristics of premixed formic acid-methane-air flames in a swirl combustor

Formic acid (FA) is a potential hydrogen energy carrier and low-carbon fuel by reversing the decomposition products, CO2 and H2, back to restore FA without additional carbon release. However, FA-air mixtures feature high ignition energy and low flame speed; hence stabilizing FA-air flames in combustion devices is challenging. This study experimentally investigates the flame stability and emission of swirl flames fueled with pre-vaporized formic acid-methane blends over a wide range of formic acid fuel fractions. Results show that by using a swirl combustor, the premixed formic acid-methane-air flames could be stabilized over a wide range of FA fuel fractions, Reynolds numbers, and swirl numbers. The addition of formic acid increases the equivalence ratios at which the flashback and lean blowout occur. When Reynolds number increases, the equivalence ratio at the flashback limit increases, but that decreases at the lean blowout limit. Increasing the swirl number has a non-monotonic effect on stability limits variation because increasing the swirl number changes the axial velocity on the centerline of the burner throat non-monotonically. In addition, emission characteristics were investigated using a gas analyzer. The CO and NO concentrations were below 20 ppm for all tested conditions, which is comparable to that seen with traditional hydrocarbon fuels, which is in favor of future practical applications with formic acid.

The Progress and the State-of-Art Facilities of Inertial Confinement Fusion

Contemporarily, as a tool to address issue of energy shortage, controlled fusion has become a hot technology. Although there are ways to achieve controlled fusion, it is currently not efficient enough to produce electricity based on power plant. The topic of this paper is to introduce a method of controlled nuclear fusion derived from laser technology, inertial confinement fusion. This research analyzed from plenty of angles in terms of its development in recent years. Firstly, the article proposes the concept of fusion and inertial confinement fusion. The main contradiction is the usage of compression to achieve high ignition points. In fact, the goal of this paper is to try to reach this ignition point in various ways. After demonstrating the basic concept of the inertial confinement fusion, mathematical expression for ignition and the principle of laser, it is found that its efficiency can be increased in several ways, i.e., amplifying lasers, adding magnetic field, and shock ignition that changes the waveform. It’s still not up to production standards, but inertial confinement fusion does give a path to achieve the goal. These results shed light on guiding further exploration for ICF as well as predict the future development direction.

Ammonia as a fuel for internal combustion engines: latest advances and future challenges

The use of ammonia as a fuel still poses a series of challenges to be overcome, both in terms of optimization and energy efficiency of the production process, and with regard to its combustion in internal combustion engines. The two main obstacles along this way are undoubtedly the high ignition temperature and the low propagation speed of the flame front due to the slow chemical kinetics of ammonia combustion process. All these issues lead to the need to use this fuel in blended mode with other more “easy burning” fuels. This need is even more felt in cases of non-stationary combustion, such as for alternative internal combustion engines but, on the other hand, it can determine an increase in engine efficiency. In this work, these ammonia technological constraints are exposed and discussed, outlining the most recent technological solutions and those under development, which will allow an increasingly widespread use of this energy carrier as a fuel in internal combustion engines. Finally, the environmental aspects related to the greater potential emission of NOx and the techniques to limit their occurrence are analyzed.

Study on injection strategy of ammonia/hydrogen dual fuel engine under different compression ratios

In order to achieve zero carbon emissions in the field of internal combustion engines, ammonia/hydrogen hybrid fuel engines are one of the best solutions. However, due to the poor ignition and combustion performance of ammonia fuel, the ammonia/hydrogen mixed fuel engine has the problems of high NOx emissions and long ignition delay, poor power performance. Therefore, this paper will study the injection strategy of ammonia/hydrogen dual fuel engine under different compression ratio to optimize the engine performance, and find the best combination of compression ratio and ammonia/hydrogen mixed fuel injection timing. In the simulation study, there are four groups of compression ratios from 13.5 to 16.5, and each group of compression ratios corresponds to eight groups of injection timing from 12°CA BTDC to 24°CA BTDC. The results show that after delaying the injection timing of ammonia/hydrogen mixture fuel, the power performance and economy of the engine are reduced, the ignition delay period is shortened, HC, CH2O, CO and soot emissions are gradually increased but at a very low level, and NOx emissions are significantly improved; After the compression ratio is increased, the engine's power performance and economy are greatly improved, HC, CH2O, CO and soot emissions are slightly higher, and NOx and N2O emissions are gradually increased. Under any combination of compression ratio coupling injection timing, the engine NOx emission can meet the Tier II emission standard. When the injection timing of ammonia/hydrogen mixed fuel is 12°CA BTDC and the compression ratio is 13.5, the NOx emission of this operation combination of ammonia hydrogen dual fuel engine can meet the Tier III emission standard. The research results of this paper can promote the engine field to zero carbon emissions and meet the Tier III emission standards, while ensuring that the engine has sufficient power.

Novel CaCO3-Based Material Formulation for Orange-Colored Spectrum Tracer Projectile

This study underlines the development of orange-colored spectrum tracer material based on Fe/CaCO3/PVC compound. The optimum composition of the compound was determined by comparing three different ratios of Fe-CaCO3-PVC. The sample with the highest CaCO3 content decomposed earlier than that of the other samples. This sample also produced the lowest calorific energy around 275.61 cal/g and emitted a medium-dark orange spectrum. The color brightness was affected by the number of color source materials as well as CaCl2 and Ca(OH)2 which were formed during the combustion process. Meanwhile, the sample with the lowest CaCO3 content produced light orange color with a sharp spectrum emission. The concentration of fuel material (Fe) as well as the higher calorific energy (466.39 cal/g) of this composition contributes to the enhanced spectrum intensity. All samples emitted the orange color, with the wavelength ranging from 585 to 593 nm. Beside of calcite as the main phase, the x-ray diffraction analysis at 650 ℃ shows Fe2O3 as a secondary phase. The FTIR analysis of the as-heated sample presents the Fe-O bending band with a broader peak, which can be attributed to the existence of Fe2O3 species. The presence of this structure made all these samples have high ignition temperature. HIGHLIGHTS The tracer formulation contain iron, CaCO3 and polyvinyl chloride Iron fuel influences the thermal stability of tracer material The tracer composition emits orange-color start from 587 to 594 nm wavelength The highest spectrum intensity found at composition with containing greatest iron fuel GRAPHICAL ABSTRACT

A rational and feasible approach to the co-management of condensates from biomass torrefaction and carbon-rich fly ash from fluidized-bed coal gasification

This study explored a promising approach to the co-management of torrefaction condensates (TCs) from biomass and carbon-rich fly ash (FA) derived from an industrial fluidized-bed coal gasifier. TC was a low-quality liquid product consisting mostly of water and a small amount of organic acids and other oxygenated organics. FA was the ultra-fine particulates with high carbon content (40–70%) and some extreme characteristics such as ultra-low volatiles, low reactivity, and high ignition temperature. The blending of FA and TC induced most of the organic components in TC to be chemically or physically adsorbed by FA, accounting for 3–13 wt% of the resultant mixtures of FA and TC (FATCs) and 11–33 wt% of the TCs. The acidic components in TC dissolved locally aggregated Ca minerals in FA, resulting in more evenly dispersed Ca on the surface of FA as an in-situ catalyst. As a result, FATCs exhibited a many-fold improvement in CO2 gasification reactivity compared to FA. And the syngas evolution rate of FATC gasification in steam-oxygen atmosphere was also remarkably elevated. In addition to the promoting effect on gasification, the combustion performance of FATCs was also greatly improved. Specifically, the ignition and burnout temperatures of FATCs were 46.5–68.5 °C and 12.4–31.7 °C lower than those of raw FA, respectively. The lower activation energy also demonstrated the higher reactivity of FATC gasification and combustion.

Cool flame wave propagation in high-pressure spray flames

Cool flame has an important impact on the performance and emission of advanced low-temperature combustion (LTC) internal combustion engines (ICEs) in which the liquid fuel is injected earlier at a lower ambient temperature (Tam) than that in the conventional diesel combustion engines. However, the cool flame characteristics of spray combustion under ICEs conditions are not fully understood, e.g., the effect of cool flame on the spray ignition and flame stabilization is not well studied. In this paper, the so-called cool flame wave propagation (CFWP) in the Engine Combustion Networks Spray A flames at three ambient temperatures Tam (800 K, 900 K and 1000 K) is analyzed using the data from large eddy simulation with an improved Eulerian based transported probability density function sub-grid combustion model. A good agreement between the LES results and experimental data is obtained for the spray liquid penetration length, vapor fuel penetration length, mean pressure rise profile, and flame liftoff length. It is shown that CFWP in the spray ignition process promotes the ignition of the fuel-rich and cold reactant mixture, leading to the most reactive mixture shifting toward fuel-richer locations due to the spatial stratification of temperature and concentration, and turbulent mixing. As a result, the high temperature ignition (HTI) can be shortened compared to the ignition in the homogeneous mixture. At Tam = 800 K, the HTI kernels are consistently formed following the CFWP propagating toward the spray head region. However, as Tam increases, the spatial correlation between HTI kernels and CFWP fronts is weakened. On the other hand, the turbulent mixing (quantified using local scalar dissipation rate) contributes more to the formation of HTI kernels at higher Tam. The present results indicate that CFWP is more profound at lower Tam in the spray ignition process. Finally, it is found that cool flame propagates mainly into pre-reacted fuel-rich mixture in an ignition wave propagation mode from the spray upstream region toward downstream region, whereas the ignition assisted flame mode is found in the spray upstream region where the combustion heat release is negligible.

Split Injection Strategy Optimization to Achieve Ideal Stratified‐Charge Mixture and Reinforce Ultralean Burn in a High Compression Ratio Direct Injection Spark Ignition Engine

Ultralean burn is considered an effective way to enhance the thermal efficiency of direct injection spark ignition engines. Herein, under ultralean burn condition, the split injection strategy is induced to investigate the in‐cylinder mixture distribution, combustion characteristics, and emissions by simulation in a high compression ratio engine model. First, the homogeneity index shows that compared with the single injection method, the split injection strategy shows better stratification of the mixture gas at the early stage of the compression stroke, which results in higher in‐cylinder pressure and heat release. Meanwhile, the results of heat balance show that split injection shows a slight effect on ignition delay, but significantly shortens combustion duration and advances CA50, and thus the exhaust loss is decreased. Second, with the decrease of a second injection fuel mass, the rich mixture is formed near the spark plug, thus reducing the ignition delay and combustion duration. Third, the split injection strategy presents faster flame kernel growth and propagation. A larger flame area is observed with the second injection mass decreasing. Finally, as the second fuel injection mass is reduced, NOx emissions increases continuously, while the soot emission decreases.

Experimental investigation on emission characteristics of high reactivity gasoline compression ignition with different EGR and injection pressure strategies

Using a High Reactivity Gasoline (HRG) in diesel engines is a promising approach to reduce NOx and soot emissions simultaneously without modifying the engine hardware. In this study, an experimental investigation on HRG and diesel emission characteristics was conducted in a six-cylinder heavy duty diesel engine with different exhaust gas recirculation (EGR) rate and injection pressure strategies. Four operation points, A25, A75, C25, and C75 in the European Steady Cycle (ESC), were studied. The pilot-main injection strategy was applied, and injection timing was adjusted to maintain a constant Crank Angle of 50 % heat release (CA50). The results show that, compared with diesel, HRG can achieve lower soot mass emission while maintaining an ultra-low NOx emission level (2–3 g/kWh) with a lower injection pressure, indicating lower cost in the fuel injection and aftertreatment systems. The particle size distribution was also analyzed for both fuels. Under high EGR rates, the accumulation mode particles were dominant for both HRG and diesel. However, under low EGR rates, diesel produced much more nucleation mode particles than HRG. The phenomenon can be explained by the difference in the pyrene and acetylene productions between paraffin and aromatic compositions.

Feasibility study of hydrogen jet flame ignition of ammonia fuel in marine low speed engine

As the global carbon emission reduction actions become more serious, the development of alternative fuel combustion solutions on engines has good prospect. Ammonia and hydrogen fuels have their own advantages and disadvantages, but the mixture of the two has good compatibility. However, in the current ammonia-hydrogen mixture combustion, spark ignition or compression ignition has certain limitations on large-bore marine engines. The development of a jet flame pilot scheme similar to pilot oil can effectively reduce the demand for hydrogen fuel and high ignition energy. A scheme of igniting ammonia fuel with a hydrogen jet flame was proposed, which realized the normal full-load power output of the marine low-speed engine. The temperature and reactivity atmosphere required for combustion brought by the jet flame to the cylinder, especially the high concentration of H radicals, helped to establish the OH and O radicals conditions required for combustion, and effectively promoted ammonia early combustion. In addition, NOx emission can meet the tier III standard by optimizing the ignition timing of the hydrogen jet flame in some case. This scheme has good potential in emissions, while relatively better power output and engine performance.

Sustainable façade cladding selection for buildings in hot climates based on thermal performance and energy consumption

Façade cladding system is essential contributor to the sustainable performance of buildings. Holistic investigation of building facade cladding performance with respect to the regional microclimate is paramount and can contribute to an under investigated research area. The research aims at analyzing the different building facade cladding systems and developing sustainable design guidelines for selecting efficient facade cladding system in hot climates. To achieve this goal, the multi-criteria method of order of preference by similarity to ideal solution is utilized to evaluate experts’ preference of façade cladding according to essential selection criteria, and an integrated environmental solutions-virtual environment simulation technique is applied to analyze thermal performance of the different cladding systems. The findings indicate that stone system is the most preferable cladding material with the highest relative closeness compared to the aluminum composite panel and plaster systems. The recommended façade system is the stone cladding which can reduce the cooling load by 4% and 1.5% compared to the aluminum panel and plaster systems, respectively. Simultaneously, it is found that polyurethane board material reduces the cooling load by 3.8% compared to sandstone with expanded polystyrene. Fire risk ranked at the top of the selection sub-criterion. The simulation demonstrates that fire risk related to the aluminum panel system can be alleviated by using high ignition point insulation materials such as mineral fiberglass and glass wool. Therefore, gravel gray stone cladding system with a cavity and mineral fiberglass is recommended in hot climates for its superior thermal performance and fire resistance.

Unsteady Flamelet modeling study on OMEx-type fuels under Engine Combustion Network Spray A conditions

Poly-Oxymethylene Dimethyl Ethers OMEx are synthetic and potentially-renewable fuels that lead to a notable reduction of the lifecycle CO2 emissions while promoting lower soot emissions than conventional Diesel fuel. In the present contribution, a computational study with a single component OME1 and a multicomponent OMEx fuel has been carried out under reference Spray A conditions from the Engine Combustion Network (ECN), which mimic in-cylinder conditions representative of Diesel engines. For both fuels, three ambient temperature conditions have been swept at constant ambient density. Calculations have been carried out using an Unsteady Flamelet Progress Variable (UFPV) combustion model and detailed chemical mechanisms. For both OMEx-type fuels, low temperature ignition in flamelet configurations start in lean mixtures, which shifts towards the fuel-rich zone and eventually leads to high temperature ignition, similar to typical hydrocarbons. In agreement with corresponding fuel cetane numbers, ignition of OMEx occurs at timings similar to those of n-dodecane, which is the reference fuel for ECN studies, while a delayed ignition is obtained for OME1. However, the actual difference in ignition timing between OMEx and n-dodecane depends on diffusion in the mixture fraction space. Moreover, ignition in spray calculations seems to occur fully on the lean side, especially for OME1, as well as for the low temperature cases. This difference in ignitable mixture range between the canonical flamelet configuration and the spray calculations results from the finite residence time for relevant mixtures in the latter case, compared to an infinite residence time in flamelets. Comparison with experiments show that the modeling approach predicts most combustion metrics for both fuels and temperature values. The combination of ambient temperature and fuel-related reactivity has enabled a transition from a short ignition lifted diffusion flame structure (OMEx at 1000–900 K) towards long ignition cases, where lift-off length may eventually be longer than the maximum length of the stoichiometric surface. This results in a reaction front stabilization at very lean conditions, i.e. a type of lean mixing-controlled flame.