Diesel Methanol Research Articles

Combustion and Emission Characteristics of Methanol–Diesel Dual Fuel Engine at Different Altitudes

Currently, in the two technological approaches for using diesel pilot injection to ignite methanol and partially substituting diesel fuel with methanol, neither can fully achieve carbon neutrality in the context of internal combustion engines. Compression-ignition direct-injection methanol marine engines exhibit significant application potential because of their superior fuel economy and lower carbon emissions. However, the low cetane number of methanol, coupled with its high ignition temperature and latent heat of vaporization, poses challenges, especially amidst increasingly stringent marine emission regulations. It is imperative to comprehensively explore the impacts of the engine geometry, intake boundary conditions, and injection strategies on the engine performance. This paper first investigates the influence of the compression ratio on the engine performance, subsequently analyzes the effects of intake conditions on methanol ignition characteristics, and finally compares the combustion characteristics of the engine under different fuel injection timings. When the compression ratio is set at 13.5, only an injection timing of −30 °CA can initiate methanol compression ignition, but the combustion is not ideal. For compression ratios of 15.5 and 17.5, all the injection timings studied can ignite methanol. Reasonable increases in the intake pressure and intake temperature are beneficial for methanol compression ignition. However, when the intake temperature rises from 400 K to 500 K, a decrease in the thermal efficiency is observed. Particularly, at an injection timing of −30 °CA, both the peak cylinder pressure and peak cylinder temperature are higher, the ignition occurs earlier, the combustion process shifts forward, and the combustion efficiency and indicated thermal efficiency are at higher levels. Furthermore, the overall emissions of NOX, HC, and CO are relatively low. Therefore, selecting an appropriate injection timing is crucial to facilitate the compression ignition and combustion of methanol under low-load conditions.

Exergy analysis of a diesel methanol dual fuel engine with different regulatory strategies for meeting China VI emission regulations

To reveal the mechanism for high brake thermal efficiency (BTE) of diesel methanol dual fuel (DMDF) engine meeting China VI emission regulations without urea, experimental and computational methods were used to study the exergy distribution with different regulatory strategies. As the methanol energy ratio (MER) increased, the incomplete combustion exergy loss increased from 0.3 % to 5.5 %, while the exhaust exergy loss and heat transfer exergy loss decreased slightly. As the HP-EGR increased from 3 % to 23 %, exergy losses of incomplete combustion and exhaust decreased, resulting in a reduction in the engine exergy losses. As the LP-EGR increased from 3 % to 21 %, the exergy losses of heat transfer and incomplete combustion slightly decreased. By advancing the main injection timing, the decrease in exhaust flow rate and temperature led to a decrease in exhaust exergy loss and the combustion efficiency was improved from 95.0 % to 96.5 %. Both of them resulted in the highest exergy efficiency of 35.2 % at 12°CA BTDC. Finally, the exergy distributions of DMDF and diesel modes were compared at high and low loads. The research results can provide theoretical basis and engineering practical value for the development and optimization of DMDF engines from the perspective of exergy.

A Study of Heat Recovery and Hydrogen Generation Systems for Methanol Engines

Biofuels are the most essential types of alternative fuels, which currently have significant potential to reduce CO2 emissions compared to fossil fuels. Methanol is a more efficient fuel than petrol due to its physicochemical properties, such as a higher latent heat of vaporization, research octane number, and heat of combustion of the fuel–air mixture. Also, biomethanol is cheaper than traditional petrol and diesel fuel for agricultural countries. The authors have proposed a new approach to improve the characteristics and efficiency of methanol diesel engines by using biomethanol mixed with hydrogen instead of pure biomethanol. Using a hydrogen–biomethanol mixture in modern engines is an effective method because hydrogen is a carbon-free, low-ignition, highest-flame-rate, high-octane fuel. A small quantity of hydrogen added to biomethanol and its combustion in an engine with a heat exchanger increases the combustion temperature and heat release, increases engine power, and reduces fuel consumption. This article presents experimental results of methanol combustion and a hydrogen-in-methanol mixture if hydrogen was retained due to the utilization of the heat of the exhaust gases. The tests were carried on a single-cylinder experimental engine with an injection of liquid methanol and gaseous hydrogen mixtures. The experiments showed that green hydrogen generated onboard the car due to the utilization of heat significantly reduced fuel costs of engines of vehicles and technological installations. It was established a hydrogen gaseous mixture addition of up to 5% by mass to methanol requires a corresponding change in the coefficient of excess air to λ = 1.25. Also, using an additional hydrogen mixture requires adjustment at the ignition moment in the direction of its decrease by 4–5 degrees of the engine crankshaft. Hydrogen gas mixture addition reduced methanol consumption, reaching a maximum reduction of 24%. The maximum increase in power was 30.5% based on experimental data. The reduction in the specified fuel consumption, obtained after experimental tests of the methanol research engine on the stand, can be implemented on the vehicle engines and technological installations equipped with an onboard heat recovery system. Such a system, due to the utilization of heat and the supply of additional hydrogen, can be implemented for engines that work on any alternative or traditional fuels.

Experimental investigation of emissions from a single-cylinder diesel engine using methanol–diesel blends

This study examines the effects of methanol–diesel blends on the emissions of a diesel engine, concentrating on carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), hydrocarbons (HCs), and particulate matter (PM). Using a single-cylinder four-stroke diesel engine at varying torque settings (2 N m–6 N m), significant reductions in CO, CO2, HC, and PM emissions were observed with increasing methanol content. CO emissions reduced by up to 81.8%, CO2 by up to 64.2%, HC by up to 80.4%, and PM by up to 23.5% with the MD11 blend. NOx emissions initially increased but decreased by up to 20% at higher torques with the same blend. These results highlight the environmental benefits of methanol–diesel blends and the need for effective NOx reduction strategies.

Insights into ensemble learning classification tools allied with near infrared spectroscopy for diesel quality management

The effective management of diesel quality is not only the fundamental guarantee for the normal operation of diesel engine, but also of realistic significance to protect the environment and personal safety. This paper presented an effective strategy for the rapid classification and determination of the compliance of diesel by using near infrared (NIR) spectroscopy, coupled with Tree-based feature selection (Tree) and popular ensemble learning frameworks. To verify the extrapolation and adaptability of ensemble learning, the light gradient boosting machine (LightGBM), extreme gradient boosting (XGBoost) and adaptive boosting (AdaBoost) which serve as baselines and their combination models with Tree method were developed to establish the models for the classification of diesel brands (case 1: −10#, −20#, −35#, −50# and inferior diesel) and alcohols diesel types (case 2: methanol diesel, ethanol diesel and pure diesel). Satisfactory results showed that all models have achieved acceptable classification results in the above two cases, especially the accuracy of Tree-LightGBM can reach more than 97 % without being affected by data imbalance and spectral overlap. The proposed approach that uses the NIR spectroscopy for diesel brands and types classification can be highly recommended as a practical, convenient, environment friendly and reliable solution for the routine monitoring of diesel market.

Study of Effects on Performances and Emissions of a Large Marine Diesel Engine Partially Fuelled with Biodiesel B20 and Methanol

The impact of fossil fuel utilisation in different combustion systems on climate change due to greenhouse gas accumulation in the atmosphere is rather evident. A part of these gases comes from the large engines used for propulsion in marine applications. In the continuous global effort made by engine manufacturers to mitigate this negative impact, one way is represented by the utilisation of alternative fuels such as biodiesel and methanol, based on dedicated research to fulfil the more stringent regulations concerning pollutant emissions issued by piston heat engines. In this study, a numerical investigation was conducted on a four-stroke large marine diesel engine (ALCO 16V 251C) at several engine speeds and full load conditions. Different blends of diesel–methanol and biodiesel B20–methanol with methanol mass fractions of 10% and 20% were considered for theoretical analysis in two techniques of methanol supply: direct injection mode of a blend of base fuel diesel/biodiesel B20 with methanol and injection of methanol after the intercooler, and direct injection of the base fuel. The results show that, if 10% in power loss can be acceptable, then for diesel–methanol 10%, in the direct injection technology, the NOx emission can be reduced up to 19%, but with a compromise of an 8% increase in SOOT emission, while for biodiesel B20–methanol 10%, with the same direct injection method, the NOx emissions increase by up to 58% with the benefit of reducing SOOT by up to 23% relative to the original diesel fuel operation. For a 20% methanol fraction in blend fuel, the drop in power is more than 10% regardless of the method of methanol supply and the base fuel, diesel, or B20 used.

An optical study on the cross-spray characteristics and combustion flames of automobile engine fueled with diesel/methanol under various injection timings

The fundamental research on the spray and combustion characteristics of diesel/methanol dual injection was explored in this study. A constant-volume combustion chamber was modified to accommodate cross-fuel injection by adding another fuel supply and an injection system. The effects of diesel/methanol injection timings on cross-spray and flame development were analysed for various injection intervals and pressures. The results showed that as the injection pressure increased, the high atomisation of the diesel–methanol mixed spray plume promoted its combustion. After diesel–methanol impingement at injection pressure of 100 MPa, a significant increase in the spray area occurred up to 62.5 % compared to its value at 60 MPa, resulting in a shortened combustion ignition delay, increased flame lift-off length and reduced soot generation. In addition, when methanol was used prior to diesel injection, the combustion ignition delay and flame lift-off length increased and soot generation decreased, as the diesel injection timings delay increased. Soot generation can be reduced by up to 33.3 % compared to that generated via the simultaneous injection of diesel/methanol at 60 MPa, by utilising a high injection pressure and proper injection timing. The study findings will provide a theoretical basis for the development of diesel/methanol dual-fuel direct-injection engines.

Methanol Combustion Characteristics in Compression Ignition Engines: A Critical Review

Methanol has been identified as a transition fuel for the decarbonisation of combustion-based industries, including automotive and maritime. This study aims to conduct a critical review of methanol combustion in compression ignition engines and analyse the reviewed studies’ results to quantify methanol use’s impact on engine performance and emissions characteristics. The diesel and diesel–methanol operation of these engines are comparatively assessed, demonstrating the trade-offs between the methanol fraction, the key engine performance parameters, including brake thermal efficiency, peak in-cylinder pressure, heat release rate, and temperature, as well as the carbon dioxide, carbon monoxide, nitrogen oxides, and particulate matter emissions. The types of the reviewed engines considering the main two combustion methods, namely premixed and diffusion combustion, are discussed. Research gaps are identified, and recommendations for future research directions to address existing challenges for the wider use of methanol as a marine fuel are provided. This comprehensive review provides insights supporting methanol engine operation, and it is expected to lead to further studies towards more efficient use of methanol-fueled marine engines.

Experimental study on engine and emissions performance of renewable diesel methanol dual fuel (RMDF) combustion

Methanol (MeOH) and renewable diesel (RD) are being considered promising alternative fuels for the de-fossilization of internal combustion engines (ICE). This study provides an experimental investigation on the use of both fuels under dual-fuel combustion mode: port fuel injection (PFI) of MeOH and direct injection (DI) of RD. The combustion mode is labeled as RMDF (renewable diesel methanol dual fuel). The experiment was performed in a heavy-duty single-cylinder engine (SCE) equipped with combustion and emissions measurements and analysis for engine efficiency and emissions of soot and NOX (oxides of nitrogen). MeOH substitution rate, which is the mass ratio of injected MeOH fuel to total injected fuels of both MeOH and RD, was varied to study its effect on engine efficiency and emissions. Different MeOH substitutions were tested from low (6.9 bar gIMEP) to full (23.5 bar gIMEP) engine load conditions at a fixed engine speed of 1200 RPM.Test results showed that higher MeOH substitution rates can reduce NOX emissions effectively while improving engine thermal efficiency. However, a higher MeOH substitute rate can result in longer ignition delay at low load, and increased emissions of carbon monoxide (CO) and unburned hydrocarbon (UHC). Increased maximum pressure rise rate (MPRR) at high load condition was observed as the MeOH substitution rate increased. MPRR is not sensitive to the change in MeOH at low load condition. While ignition delay became longer at low load, it was shorter at high load as MeOH substitution rate increased. Overall, the results from this study suggest that RMDF can be considered as an option to achieve a cleaner and more efficient engine. However, further optimization of combustion designs and engine operating strategy need to be considered to improve combustion loss from RMDF emissions, possibly due to the lower reactivity of MeOH.

Effect of EGR on performance and emissions of a methanol–diesel reactivity controlled compression ignition (RCCI) engine

Effect of EGR on performance and emissions of a methanol–diesel reactivity controlled compression ignition (RCCI) engine

Experimental Investigation of the Performance and Unburned Methanol, Formaldehyde, and Carbon Dioxide Emissions of a Methanol-Diesel Dual-Fuel Engine

In the context of global efforts to pursue carbon neutrality, the methanol-diesel reactivity controlled compression ignition (RCCI) combustion has become a promising strategy for diesel engines to reduce emissions with higher thermal efficiency. To further improve the fuel economy of the methanol–diesel RCCI engine and reduce its unregulated emissions, the effects of methanol substitution rate (MSR) and exhaust gas recirculation (EGR) on fuel economy, CO2, MeOH, and H-CHO emissions at different engine speed and load conditions were tested. The conversion efficiency of a conventional diesel oxidation catalyst (DOC) in oxidizing the unregulated emissions under the World Harmonized Steady-State Cycle (WHSC) was also evaluated. The results showed that running the engine in methanol-diesel RCCI mode can significantly improve fuel economy at medium to high loads [greater than 1.18 MPa brake mean effective pressure (BMEP)]. The equivalent brake specific fuel consumption (ESFC) in the RCCI mode was lower than that of the baseline CDC mode, and the utilization of EGR can further improved fuel economy at lower load conditions. The MeOH and H-CHO emissions increased as the MSR increased, and they decreased as the load level and EGR rate increased. The CO2 emissions decreased as the MSR increased, but they increased as the EGR rate increased. The conversion efficiencies of DOC for MeOH, H-CHO and aromatic hydrocarbons (AHC) were around 93%, 84%, and 61%, respectively, under the WHSC test. Exhaust after-treatment by DOC is an effective solution to reduce unburned MeOH and H-CHO from methanol-diesel dual-fuel engines, and to extend RCCI operating range.

Combustion Characteristics of Diesel Methanol Blended Fuel Ship Engines

With increasingly stringent fuel emission control in some river traffic control zones and inland waters, this paper addresses the problem of substandard diesel fuel emissions, relying on the theoretical basis of numerical simulation of diesel engine in-cylinder combustion. The combustion and emission characteristics of diesel-water-mixed methanol blended fuel are simulated and analyzed based on the AVL FIRE software. The combustion model of the diesel engine was established, and the changes of in-cylinder pressure, temperature, heat release rate, and emission concentration were investigated for D85W10, D85W15, and D85W20 blends respectively, which were compared with diesel. The results show that as the proportion of water in the fuel mixture increases, the in-cylinder temperature gradually increases, the in-cylinder pressure slightly decreases, the heat release rate does not change much, and the NO and Soot emissions decrease.

A Phenomenological Combustion Model for Diesel–Methanol Dual-Fuel Engines

Abstract Strict emission regulations and energy security concerns have led to various alternative concepts for the engine operation. Diesel–Methanol dual-fuel combustion solution has gained momentum over the past decade due to the fact that the technology required to convert a pure diesel engine to a dual-fuel one is mature, and methanol is a well-known substance in the industry. However, designing, tuning, and optimizing these engines require fast and reliable simulation models. For this purpose in the present study, a phenomenological combustion model, for a four-stroke port-injected methanol diesel engine, is established. The model is tuned with in-cylinder combustion data. The heat release rate is estimated via a triple-Wiebe function. Ignition delay is modeled with an Arrhenius-type expression, utilizing the methanol and diesel equivalence ratio, among other operational parameters. Other model parameters are obtained from data-driven functions, correlating the basic parameters of the combustion. The data used for model calibration and validation were generated with a computational fluid dynamic numerical model, and it was verified with data provided in the literature.

Effects of exhaust gas recirculation (EGR) rates on emission characteristics of ethanol and methanol diesel blended fuels

The introduction of ever more stringent diesel emission standards is associated with a reduction in greenhouse gases. These limitations push many researchers working in this field to look for alternative solutions with the aim of lower greenhouse gas emissions. One of the alternatives is the use of alternative fuels and additives in order to reduce the consumption of fossil fuels. The use of alternative fuels such as ethanol, methanol and others in combination with traditionally used technologies such as exhaust gas recirculation (EGR) is one of the solutions that would lead to the limitation of diesel engines emissions. The aim of the present study is to investigate the performance of a diesel engine with ethanol and methanol additives combined with different degrees of recirculation on engine emissions. For this purpose, a model of a diesel engine with EGR with the possibility of working with ethanol and methanol additives has been developed.

Emissions Characteristics of Methanol-Diesel Blends in CI Engines

Due to the energy crisis and pollution problems, investigations have focused on decreasing fuel consumption and lowering the concentration of toxic components in combustion products by using alternative, non-petroleum and non-polluting fuels. While conventional energy sources such as natural gas, oil and coal are non-renewable, alcohol can be coupled to renewable and sustainable energy sources. In this study, the combustion characteristics and emissions of diesel fuel and methanol blends were compared. The tests were performed at steady state conditions in a four-cylinder DI diesel engine at full load at 1500-rpm engine speed. The experimental results showed that diesel methanol blends provide significant reductions in CO, unburned HC, and limited increase in NOx emissions. In addition, a reduction in engine noise was demonstrated by increasing methanol portion in blends.

Determination of Carbonyls Compound, Ketones and Aldehydes Emissions from CI Diesel Engines Fueled with Pure Diesel/Diesel Methanol Blends

Quantitative and qualitative analyses of chemical species out of CI engine tailpipe emissions fueled with pure diesel and diesel methanol blends, trapped in dinitro phenylhydrazine (DNPH) solutions, were performed. The formed hydrazine was studied using high-performance liquid chromatography (HPLC) accompanied by a detector for ultraviolet (UV). A set of carbonyl-DNPH derivative standards was developed and compared with engine tailpipe gases produced by both fuel modes. An understanding of carbonyl chemical compounds such as formaldehyde, acetaldehyde, and acrolein (HCHO, CH3CHO, and H2 = CHCHO, respectively) is essential for researchers to know how these chemicals affect human health and the environment. In both fuel modes, acetaldehyde was the main combustible product 25 ppm followed by formaldehyde 17 ppm, croton aldehydes 16 ppm, acrolein 12 ppm, and iso-valerdyhyde 10 ppm. In addition to these species, only a few other chemical species were detected in the exhaust gas. According to this study, carbonyl compounds from blended fuel contribute 15–22% of pure diesel fuel emissions. As shown by the results, engine operating conditions and fuel mode have a strong impact on the total amount of carbonyls released by the engine. Engine performance was highly influenced by different fuel modes and engine speeds. Using pure diesel, the regulated emissions, HC, CO, and NOx, registered high concentrations at a lower speed (1500 rpm) and NOx presented with the highest concentration of 4 g/kWh followed by CO with 1 g/kWh and HC with 0.5 g/kWh.

Experimental investigation on combustion and emission characteristics of diesel methanol dual fuel (DMDF) engine at various altitudes

In order to reveal the effects of diesel and diesel methanol dual fuel (DMDF) on engine performance at different altitudes, especially on combustion stability. In this study, a comparison of experimental research on characteristics of combustion, economy, and emissions for a turbocharged DMDF at various simulated altitudes (10m, 700m, 1670m, and 2400m) and three working conditions (1200rpm-72 Nm, 1800rpm-158 Nm, and 2200rpm-153 Nm) were conducted and analyzed combustion characteristics, economy and emissions. At 1800rpm and 2200rpm, with the increment of altitude, the peak value of the cylinder pressure, the pressure rise rate, and the brake thermal efficiency (BTE) for DMDF mode were higher than diesel mode, while combustion center (CA50) and combustion duration of diesel mode higher than DMDF mode. At 1200rpm and 1800 rpm, the maximum heat release rate (HRR) of DMDF mode was higher than diesel mode. When the altitude rose from 10m to 2400m, the coefficient of variation of peak pressure (COVPP) of DMDF mode increased while the coefficient of variation of indicated mean effective pressure (COVIMEP) of DMDF mode decreased, which means the combustion of dual-fuel is relatively stable. The exhaust temperature of DMDF mode was lower than that of diesel mode at various altitudes. Compared with diesel mode, NOX and Soot emissions in DMDF model significantly decreased at different altitudes and working conditions.

HCCI combustion of methanol along with diesel through novel injection strategies and its potential over conventional dual fuel combustion

In this experimental work Homogenous Charge Compression Ignition of methanol along with direct injection of diesel (HCCI-DI) was achieved by adapting novel injection strategies for controlling the charge homogeneity and ensuring proper combustion in a single cylinder common rail water cooled research engine run at a constant speed of 1500 rpm. Methanol was port injected while the diesel was injected as two pulses – an early first pulse (during start of suction) for enhancing the charge homogeneity and a late second pulse for controlling ignition. The effects of methanol energy share (MES), start of injection of the first and second pulses (SOI-F and SOI-S) and first pulse injected quantity (FIQ) at different loads were studied. The SOI-S of diesel had to be advanced with load for best thermal efficiency. At full load, it had to be retarded to limit knocking. Heat release analysis indicated that higher FIQs resulted in slow combustion as the charge was more homogeneous while lower FIQs formed a stratified mixture that enhanced the thermal efficiency, reduced THC and unregulated emissions while elevating the NOx levels. The thermal efficiencies were higher by about 2.9 and 1.9% compared to the Conventional Dual Fuel (CDF) operation at 75% and 50% loads. The MES that could be tolerated was higher than the CDF mode. Soot was significantly reduced as compared to the CDF mode by 94%, 87.6%, 80.3% while the NOx was reduced by 77.5%, 65.2% and 29.9% at the IMEPs of 5.1, 6.2 and 7.5 bar respectively. However, emissions of unburnt hydrocarbons, carbon mono-oxide, methanol and formaldehydes were higher than the CDF mode. On the whole the methanol diesel HCCI-DI mode has the potential for operation with higher efficiency, lower NOx and soot emissions than the CDF mode.

Experimental Study of Cyclic Variations of RCCI Diesel–Methanol Engines at Multiple Simulated Elevations

Abstract The cyclic variations of reactivity-controlled compression ignition (RCCI) combustion are studied in this work via experiments conducted in an in-house diesel–methanol dual-fuel (DMDF) engine at multiple simulated elevations. The test engine is maintained at 1800 rpm, with simulated elevations of 10, 700, and 1670 m. Engine load, methanol substitution rate (MSR), and injection parameters are varied to investigate their effects on cyclic variations at multiple elevations. We employ in-cylinder pressure parameters, such as the maximum pressure (Pmax) and indicated mean effective pressure (IMEP), to quantify cyclic variations. According to the results, the stability of DMDF combustion in plateau conditions displays a similar trend to that in plain conditions. However, with the increase in elevation, there is a significant increase in the Pmax coefficient of variation (COVPmax), while that of the IMEP (COVIMEP) shows an opposite trend. The distribution of crank angle at high elevations corresponding to Pmax tends to be more concentrated, and the increase in pilot injections reduces the COVPmax in the plateau environment. At all elevations, there is no effect of injection timing on COVIMEP, while COVPmax is more sensitive to injection timing (range from 10 deg CA before top dead center (BTDC) to 3 deg CA BTDC). Compared with other injection parameters, the cyclic variations caused by injection pressure (range from 92 MPa to 112 MPa) are relatively minor.

Influence of Pilot Injection on Combustion Characteristic of Methanol–Diesel Dual-Fuel Engine

An experimental study regarding methanol–diesel dual-fuel (DF) engines was conducted on a modified engine to explore the effects of pilot injection timing and period on the two-stage combustion process caused by the pilot injection strategy. In this study, the two-stage combustion process was determined according to the first two peaks of the second derivative of an in-cylinder pressure (d2p/dφ2) curve. The results show that the peak pressure rise rate (PRR) tended to decrease with advancing pilot injection timing at a high co-combustion ratio (CCR), which reduced combustion noise. The start of the combustion of the main injection diesel (SOC2) could be advanced by increasing the pilot injection period or advancing pilot injection timing at a 42% CCR. At an 18% CCR, the pilot injection timing and period had no significant effect on SOC2. With the advancement of pilot injection timing, the start of the combustion of pilot injection diesel (SOC1) advanced, and generally, the coefficient of variation of the PRR (COVPRR) of the two-stage combustion process increased first and then decreased. However, with the increase in the pilot injection period, SOC1 almost always remained constant and the COVPRR of the two-stage combustion process generally increased.