Diesel Methanol Research Articles

Strategies for Improved Stability of Methanol-in-Diesel Emulsions

Abstract This study is motivated by the need to present a robust methodology for preparing stable methanol-in-diesel emulsions for use in compression ignition engines with the specific objective of maximizing the methanol content. Specifically, it involved exploring the feasibility of methanol-in-diesel emulsions with conventional surfactants such as Tween-80 and Span-80 and nonconventional surfactants such as 1-dodecanol, pentanol, and butanol. The hydrophilic–lipophilic balance (HLB) values of the surfactant varied from 7 to 15 to investigate the role of the surfactant HLB on the stability of the macroemulsion. It is observed that the macroemulsion with an HLB value of 10 provides the best stability results. Using surfactant HLB value of 10, three macroemulsions with 10 wt%, 15 wt%, and 20 wt% of methanol were prepared using ultrasonication. However, only the macroemulsion with 10 wt% of methanol was observed to be stable for at least 20 days after preparation. Next, the microemulsions of diesel–methanol were produced by using nonconventional surfactants such as 1-dodecanol, pentanol, and butanol. Among these, 1-dodecanol was found out as the most suitable surfactant owing to its ability to form microemulsions with any mixing ratio of diesel–methanol and its high cetane number (63.6). This study has clearly brought out the strategies for preparing both macro and microemulsions. Overall, the results presented in the current work are expected to aid efforts in adapting compression ignition engines for diesel–methanol fuel blends.

Influence of the Port Height to Stroke Ratio on the Performance of an OP2S Engine Fueled with Methanol/Diesel

Zero carbon emission is a mainstream trend in the development of internal combustion engines (ICEs) in the future. ICEs need to constantly surpass the existing working mechanism, especially in order to explore the possibility of new combustion methods. Dual-fuel combustion is a good way to reduce carbon emissions and achieve clean combustion. However, the traditional internal combustion engine is limited by its own structure, restricting its performance improvement. The opposed-piston, two-stroke (OP2S) diesel engine is a potential power system with a high degree of structural adjustability. Therefore, this work attempted to apply methanol/diesel dual-fuel to OP2S engines in order to explore efficient and clean combustion modes in the future. In this work, a one-dimensional simulation model of an OP2S diesel engine was established and verified. The effect of the port height to stroke ratio on the performance of the OP2S diesel engine was mainly studied for different methanol blending ratios. The results show that the methanol blending ratio does not affect the port height to stroke ratio where the optimal values of the MIP and scavenging efficiency appear. The optimal methanol blending ratio for the power performance of OP2S diesel engines is 5~15%. There is a trade-off relationship between the MIP/scavenging efficiency and trapping efficiency. For the optimization of an OP2S methanol–diesel engine, priority should be given to ensuring an optimal MIP and scavenging efficiency, and then to the appropriate consideration of the trapping efficiency.

A critical review: Application of methanol as a fuel for internal combustion engines and effects of blending methanol with diesel/biodiesel/ethanol on performance, emission, and combustion characteristics of engines

AbstractThis article presents a comprehensive overview of methanol as a potential oxygenated fuel for internal combustion engines. Here two approaches have been examined to evaluate the utilization of methanol, namely blending with diesel/biodiesel/methanol and premixing with intake air or fumigation. In conventional compression ignition engines, up to 95% and 25% diesel can be replaced by methanol through fumigation and blending, respectively. Higher latent heat of vaporization of alcohol led to lower peak in‐cylinder pressure and NOx; however, it negatively affects thermal efficiency and hydrocarbon and carbon monoxide emissions. Fumigation of alcohol requires modifications in the existing engine, whereas blending needed surfactants or additives to produce stable alcohol–diesel blends. High injection pressure and late direct injection, methanol–diesel blends have shown lower emissions and proved their potential as a suitable replacement for ethanol–diesel blends from the components durability perspective.

Study on methanol premixed coupled with EGR to achieve ultra-low emissions in diesel engine

In this paper, an experimental investigation on achieving ultra-low emissions in diesel engine was carried out using intake premixed methanol and EGR technology. The influence of EGR introduction method on combustion and performances were studied comprehensively. The results show that ultra-low NOx (<0.4g/kWh) and PM (<10mg/kWh) emissions can be achieved simultaneously in diesel methanol dual fuel (DMDF) highly premixed low-temperature combustion mode. Compared with low-pressure EGR (LP-EGR), the excess air coefficients under high-pressure EGR (HP-EGR) drops more significantly. At the same EGR rate, the in-cylinder mean temperature and equivalent of mixture are higher under HP-EGR conditions, which results in higher combustion efficiency, lower CO and THC emissions. The maximum brake thermal efficiency of high-pressure EGR is 9.6% higher than that of low-pressure EGR.

Experimental study on ultra-low raw emissions in diesel/methanol dual fuel engine based on dual-loop EGR

In this paper, an experimental investigation on achieving ultra-low raw emissions in a diesel/methanol dual fuel engine based on dual-loop EGR was carried out. The effect of dual-loop EGR (High pressure EGR and low pressure EGR) on the combustion, performance and emissions of methanol engine has been studied comprehensively. The results show that ultra-low NOx (<0.4g/kWh) and PM (<10 mg/kWh) emissions can be achieved simultaneously in diesel methanol dual fuel engine with the help of EGR. The combustion phase is delayed with the increase of EGR rate in both EGR modes. However, the methanol equivalence ratio and in cylinder combustion temperature in high pressure EGR mode are significantly higher than those in low pressure EGR mode. Therefore, the CO and THC emissions are obviously lower in high pressure EGR mode than that in low pressure EGR mode. The combustion efficiency and brake thermal efficiency of the engine are 1.9% and 9.6% higher in high pressure EGR mode than those in low pressure EGR mode, respectively.

THE POTENTIAL OF METHANOL AS AN ALTERNATIVE MARINE FUEL FOR INDONESIAN DOMESTIC SHIPPING

This analysis aims to provide insight and to explore the future usage of methanol as an alternative marine fuel for domestic ships in Indonesia. An overview of potential application, analysis of resources availability, and stakeholder readiness on the topic are provided; related challenges are also identified and further examined. The potential performance of methanol as a fuel is discussed and evaluated via two different perspectives (the ship-owner perspective and the government one) through case studies of two passenger ships owned by the shipping company Pelayaran Indonesia (PELNI): MV. Labobar and MV. Gunung Dempo. As ship-owners tend to look very closely at the economic aspects, a feasibility study is performed by developing a combinatorial scenario approach based on the combination of economic measures of merit (NPV and payback period) along with a technical scenario (main-pilot fuel set-up); the variables included in the calculation are: ship age, ship productivity, and macro-economy conditions. Regarding the government perspective, the main issues are environmental protection and policy compliance. These issues are evaluated by examining six emission types (NOx, SOx, CO2, CH4, N2O, and PM). Additionally, since there is a trade-off situation in government subsidies between the government and ship-owner interests, an optimisation and sensitivity analysis is performed by utilizing a combinatorial scenario model to determine optimum methanol price and external variables influencing the decision to support further use of methanol in the Indonesian market. An important finding was that Indonesia has certain advantages/drives to introduce methanol as a marine fuel. However, methanol competitiveness is mainly dependent on ship productivity and the price difference between methanol and marine diesel oil (MDO). Additionally, policy analysis (through an optimisation approach) could be one of the government options in order to determine the optimum condition in establishing methanol as a marine fuel. Finally, short, medium, and long term recommendations are also provided as the basis for future consideration.

Investigation of the Performance and Emission Characteristics of a Diesel Engine with Different Diesel–Methanol Dual-Fuel Ratios

In this paper, the effects of different diesel–methanol blends on the combustion and emission characteristics of diesel engines are investigated in terms of cylinder pressure, heat release rate, cylinder temperature, brake specific fuel consumption, thermal brake efficiency, brake power, and soot, nitrogen oxides, and carbon monoxide emissions in a four-stroke diesel engine. The corresponding three-dimensional Computational Fluid Dynamics (CFD) model was established using the Anstalt für Verbrennungskraftmaschinen List (AVL)-Fire coupled Chemkin program, and the chemical kinetic mechanism, including 135 reactions and 77 species, was established. The simulation model was verified by the experiment at 50% and 100% loads, and the combustion processes of pure diesel (D100) and diesel–methanol (D90M10, D80M20, and D70M30) were investigated, respectively. The results showed that the increase in methanol content in the blended fuel significantly improved the emission and power characteristics of the diesel engine. More specifically, at full load, the cylinder pressures increased by 0.78%, 1.21%, and 1.41% when the proportions of methanol in the blended fuel were 10%, 20%, and 30%, respectively. In addition, the power decreased by 2.76%, 5.04%, and 8.08%, respectively. When the proportion of methanol in the blended fuel was 10%, 20%, and 30%, the soot emissions were decreased by 16.45%, 29.35%, and 43.05%, respectively. Therefore, methanol content in blended fuel improves the combustion and emission characteristics of the engine.

Determination of alcohols-diesel oil by near infrared spectroscopy based on gramian angular field image coding and deep learning

Alcohols blended with diesel, as a renewable and clean substitute fuel of diesel engine, is a potential solution to alleviate the scarcity of fossil fuels and the worsening environmental pollution in transportation and industry. In this study, a novel near infrared (NIR) application for determination of alcohols-diesel is presented. Using the strategy of combining NIR spectroscopy with gramian angular field (GAF) image coding and deep convolution neural network (CNN), the proposed approach successfully realized the qualitative classification of different diesel (methanol diesel, ethanol diesel and pure diesel) and alcohols content detection despite the spectra were highly similar and collinear. To further verify the practical performance of the proposed method, it was briefly compared with 1DCNN, support vector machine (SVM) and BP neural network based on the identical data. The proposed GAF-CNN method can accurately distinguish diesel, methanol diesel and ethanol diesel. In addition, satisfactory results have been achieved with the smallest MSE and MAE and the highest R2 in the quantitative detection of methanol and ethanol content. This study explores the conversion of 1D spectra into 2D images through the mathematical of GAF, which not only opens up a new perspective for more intuitive display of spectral features, but also makes it possible to introduce the powerful advantages of deep learning image processing into the field of NIR analysis. The proposed method provides a new idea for the intelligent determination of alcohols-diesel.

Effect of Methanol/Water Mixed Fuel Compound Injection on Engine Combustion and Emissions

Due to the recent global increase in fuel prices, to reduce emissions from ground transportation and improve urban air quality, it is necessary to improve fuel efficiency and reduce emissions. Water, methanol, and a mixture of the two were added at the pre-intercooler position to keep the same charge and cooling of the original rich mixture, reduce BSFC and increase ITE, and promote combustion. The methanol/water mixing volume ratios of different fuel injection strategies were compared to find the best balance between fuel consumption, performance, and emission trends. By simulating the combustion mechanism of methanol, water, and diesel mixed through the Chemkin system, the ignition delay, temperature change, and the generation rate of the hydroxyl group (−OH) in the reaction process were analyzed. Furthermore, the performance and emission of the engine were analyzed in combination with the actual experiment process. This paper studied the application of different concentration ratios of the water–methanol–diesel mixture in engines. Five concentration ratios of water–methanol blending were injected into the engine at different injection ratios at the pre-intercooler position, such as 100% methanol, 90% methanol/10% water, 60% methanol/40% water, 30% methanol/70% water, 100% water was used. With different volume ratios of premixes, the combustion rate and combustion efficiency were affected by droplet extinguishment, flashing, or explosion, resulting in changes in combustion temperature and affecting engine performance and emissions. In this article, the injection carryout at the pre-intercooler position of the intake port indicated thermal efficiency increase and a brake specific fuel consumption rate decrease with the increase of water–methanol concentration, and reduce CO, UHC, and nitrogen oxide emissions. In particular, when 60% methanol and 40% water were added, it was found that the ignition delay was the shortest and the cylinder pressure was the largest, but the heat release rate was indeed the lowest.

To achieve high methanol substitution ratio and clean combustion on a diesel/methanol dual fuel engine: A comparison of diesel methanol compound combustion (DMCC) and direct dual fuel stratification (DDFS) strategies

Diesel methanol compound combustion (DMCC) suffers from poor fuel economy at low load and knock at high load. A direct dual fuel stratification (DDFS) strategy in which diesel is injected before the top dead center (TDC) and methanol is directly injected after the auto-ignition of diesel has been proposed and investigated in previous research. In this study, a three-dimensional simulation model coupled chemical reaction kinetic mechanism is used to investigate and compare the DMCC and DDFS strategies. In the former strategy, the ratio of methanol energy to total fuel energy (Rm) is limited by inefficient combustion at low load, and although fuel economy can be improved by advancing diesel injection and increasing initial temperature, Rm still cannot exceed 30%. Moreover, Rm is limited by knock at high load; however, knock intensity can be suppressed by delaying diesel injection and increasing exhaust gas recirculation (EGR) rate, allowing Rm to reach values as high as 50%. In contrast, the latter strategy can yield Rm values as large as 90%, stable combustion, good fuel economy, and low emissions without intake air heating and EGR. In short, the DDFS strategy is a promising way of applying methanol to diesel engines.

Numerical investigation and experimental validation on the leakage of methanol and formaldehyde in diesel methanol dual fuel engine with different valve overlap

The diesel methanol dual fuel (DMDF) engine is confronting with the problem of high unregulated emissions of methanol and formaldehyde. The previous studies on unregulated emissions of DMDF engine focused on the measuring methanol and formaldehyde concentrations in the exhaust without distinguishing whether emissions come from leakage during valve overlap or incomplete combustion in the cylinder. In this study, a computation fluid dynamics (CFD) model coupled with a detailed chemical kinetic mechanism was developed to investigate the methanol and formaldehyde emissions of DMDF engine. The results showed that the unburned methanol and formaldehyde in the cylinder were the main part of the total methanol and formaldehyde emissions based on the 41 °CA valve overlap of simulation model. Then the effects of different intake valve opening (IVO) and exhaust valve closing (EVC) on methanol emissions were investigated. The results showed that only increasing IVO or EVC had very little effect on the leakage of methanol during scavenging. However, when the IVO and EVC changed simultaneously, the valve lift would significantly increase during the valve overlap of scavenging, which had a great impact on methanol leakage. The simulation results were validated by experiments in a 6170 marine engine. The experimental results were consistent with the simulation results and the increase of effective flow area caused by valve lift during large valve overlap was the most important reason for the increase of methanol emission. Therefore, all engines have almost no leakage in small valve overlap. However, with the increase of valve overlap, the actual results were different due to the different valve lift and mixture concentration of different engines.

Multiple combustion modes existing in the engine operating in diesel methanol dual fuel

Four typical combustion modes were found in a diesel methanol dual fuel (DMDF) engine, which subverted the traditional viewpoint that the methanol was only ignited by diesel fuel spray. In this manuscript, the results of different combustion modes from constant volume combustion chamber (CVCC), compression ignition (CI) engine and numerical simulations were presented. In DMDF mode 1, diesel and methanol mixture were ignited simultaneously by compression. The role of diesel was the cetane number improver of methanol. In DMDF mode 2, part of diesel formed the mixture of theoretical equivalent ratio and was firstly ignited. Therefore, the role of the firstly ignited diesel in the combustion process was to ignite methanol. In DMDF mode 3, premixed methanol was auto-ignited before diesel injection, which resulted in two obvious heat release rate (HRR) peaks of methanol combustion and diesel combustion in the cylinder. In DMDF mode 4, the combustion process was slow. Therefore, the duration of combustion increased and a large amount of methanol remained unoxidized at the end of the combustion. The role of diesel in this mode was pilot ignition. The thermal efficiency of the first and second combustion modes was higher among the four combustion modes, and the first one was the highest. The results obtained will provide more clean and high thermal efficient combustion mode for dual fuel engines.

Effect of EGR strategy on combustion and emission of DMDF engine for meeting China VI emission legislation

Study on EGR mode and demand were carried out to meet with the requirements of main emission limits of China VI on a diesel methanol dual fuel (DMDF) engine equipped with Hybrid exhaust gas recirculation (EGR) system coupled with back pressure valve (BPV). According to the World Harmonized Steady-State Cycle (WHSC) test cycle, the effects of EGR mode under high methanol energy ratio (MER) on the combustion, emissions and economy of DMDF engines were studied without the help of selected catalyst reduction (SCR). Considering the weight based on WHSC test cycle of full load was only 0.083, and EGR demand of full load was low, the optimal EGR strategy under different loads except full load was determined for DMDF engine. The results demonstrated that through the early injection strategy with high MER, particulate matter (PM) emissions were all at an extremely low level, far below the requirements by legislation limit of 0.01 g/kWh. With the increase of EGR rate, nitrogen oxides (NOx) emissions were significantly reduced under different loads, accompanying with one or more EGR modes at 25%, 50%, and 70% loads to ensure that NOx emission could meet the requirements by legislation limit of 0.4 g/kWh, while PM emissions were at a very low level at the same time. Demand for EGR rate of light loads was generally higher than that for medium loads, but under light loads, each of hybrid EGR modes could meet the demand of China VI legislation. While under medium loads, the dual loop (DL) EGR modes, i.e., both low pressure (LP) and high pressure (HP) EGR mode must be needed. In LP EGR mode combined with back pressure valve (BPV), higher EGR rate was required under the same NOx control target, owing to the higher intake air volume than those of other modes. The trade-off relationship in HP_BPV mode between NOx and PM emissions still existed, and high EGR rate often leaded to an increase in PM.

Study on the influence of alumina nanomethanol fluid on the performance, combustion and emission of DMDF diesel engine

With the increasingly strict domestic emission regulations, how to reduce diesel emission without affecting its output power has become a hot and important research topic. Due to their unique physical and chemical properties, the combined use of methanol and Al2O3nanoparticles plays a unique role in promoting combustion and reducing emissions. In this study, Al2O3methanol nanofluid fuel was injected into the inlet and diesel fuel was injected into the cylinder to explore the influence of Al2O3nanoparticles on the performance, combustion and emissions of diesel methanol dual fuel (DMDF) entered. The experienced results showed that with the addition of Al2O3nanoparticles in methanol, the peak pressure and heat release rate in the cylinder of the diesel engine were improved, the combustion delay period and the combustion duration were shortened, the fuel consumption rate was reduced by up to 10.8%, and the braking thermal efficiency was increased by 12.11% at most. With the addition of Al2O3nanoparticles, NOx, CO, HC and soot ratio emissions of the engine were reduced, among which the NOx reduction ratio was small, and the maximum reduction ratio of the last three was 28.82%, 83.33% and 29.27% respectively.

Impacts of octanol and decanol addition on the solubility of methanol/hydrous methanol/diesel/biodiesel/Jet A-1 fuel ternary mixtures.

This study attempts to enhance the mixture instability of methanol/hydrous methanol mixed with diesel fuel, waste cooking oil (WCO) biodiesel, and Jet A-1 fuel using n-octanol and n-decanol as cosolvent at numerous temperatures of 10 °C, 20 °C, and 30 °C. The experiment is divided into two stages: first, blending pure methanol with diesel oil, Jet A-1, and WCO biodiesel individually utilizing n-octanol and n-decanol as cosolvent at various temperatures. Second, combining hydrous methanol (90% methanol + 10 wt% water) with diesel oil, Jet A-1, and WCO biodiesel independently and applying n-octanol and n-decanol as cosolvent at different temperatures. Pure methanol or hydrous methanol is mixed with the base fuels at different mixing proportions varying from 0 to 100 vol% with 10 vol% increments. The co-solvent, mainly n-octanol and n-decanol (titrant), is progressively and separately inserted into the tube with continuous shaking by utilizing a high-precision pipette until the ternary mixtures' phase borders seem. The findings demonstrate phase separation in pure methanol–diesel and pure methanol–Jet A-1 combinations even when the blend temperature increased to 60 °C. The pure methanol/biodiesel combination proves complete solubility without adding an external agent. The results also illustrate that the ambient temperature considerably affects the stability of mixture and amount of cosolvent in the blend. n-Octanol and n-decanol showed promising performance in enhancing the phase stability issue of methanol and hydrous methanol with the base fuels. It can be deduced that the minimum amount of cosolvent is recorded for biodiesel–hydrous methanol, Jet A-1–hydrous methanol, and diesel–hydrous methanol, respectively.

In-depth comparison between pure diesel and diesel methanol dual fuel combustion mode

Diesel Methanol Dual Fuel (DMDF) could achieve high efficiency and low emissions simultaneously at part of engine conditions, but the reason of this has not been clarified. In order to find the reason behind this phenomenon, Pressure-Volume (P-V) map, equivalence ratio (φ)-temperature (T) map and three-dimensional simulation software were used to compare diesel and DMDF mode, and two test conditions were selected to fulfill in-depth comparison of two combustion modes. Based on the analysis of P-V map, the reason of higher thermal efficiency at DMDF mode is as follows: lower cylinder pressure in compression stroke contributes to compression work reduction. Meanwhile, higher combustion rate of DMDF mode could reduce cylinder temperature and pressure in the late power stroke, which would further decrease exhaust loss and heat loss. Based on the analysis of φ-T map, higher methanol substitution percent could reduce the intersection area between cylinder φ-T map and nitric oxide & soot generation region. And after analyzing in-cylinder temperature, hydroxy mole fraction together with the equivalent ratio three-dimensional cloud map, it is found that the inhibitory effect of methanol on diesel low-temperature combustion prolongs diesel ignition delay, which helps to form the homogeneous charge in the cylinder. Under DMDF mode, fuel rich areas are significantly reduced, so is the maximum in-cylinder temperature. This is the key to achieve ultra-low nitrogen oxides and soot emissions for DMDF mode.

Exploring the high load potential of diesel–methanol dual-fuel operation with Miller cycle, exhaust gas recirculation, and intake air cooling on a heavy-duty diesel engine

Legislations concerning emissions from heavy-duty diesel engines are becoming increasingly stringent. This requires conventional diesel combustion to be compliant using costly and sophisticated aftertreatment systems. Preferably, diesel–methanol dual-fuel is one of the suitable alternative combustion modes as it can potentially reduce the formation of nitrogen oxide and soot emissions which characterised the diesel mixing-controlled combustion. This is primarily due to the high latent heat of vaporisation and oxygen content of the methanol fuel. At high engine loads, however, the potential of diesel–methanol dual-fuel operation is constrained by the excessive combustion pressure rise rate and peak in-cylinder pressure, which limits both the engine efficiency and the percentage of methanol that can be used. For the first time, experimental studies were conducted to explore advanced combustion control strategies such as Miller cycle, exhaust gas recirculation, and intake air cooling for improving upon high load diesel–methanol dual-fuel combustion. Experiments were carried out at 1200 r/min and 18 bar indicated mean effective pressure on a single-cylinder heavy-duty diesel engine, which equipped with a high pressure common rail diesel injection, a methanol port fuel injection, and a variable valve actuation system on the intake camshaft. Results showed that the methanol energy fraction of a conventional diesel–methanol dual-fuel operation with a baseline intake valve closing timing was limited to 28%. This was due to the high combustion temperature at a high load which advanced the ignition timing of the premixed charge, resulting in high levels of pressure rise rate. The application of lower effective compression ratio and intake air temperature ( Tint) effectively decreased the compression temperature, which successfully delayed the ignition timing of the premixed charge. This allowed for a more advanced diesel injection timing to achieve improvement in the thermal efficiency and potentially enabled a higher methanol substitution ratio. Although the introduction of exhaust gas recirculation demonstrated very slight impact on the ignition timing of the premixed charge, a higher net indicated efficiency was observed due to a relatively lower local combustion temperature which reduced heat transfer loss. Moreover, the optimised diesel–methanol dual-fuel operation allowed a higher methanol energy fraction of 40% to be used at an effective compression ratio of 14.3 and Tint of 305 K and achieved the highest net indicated efficiency of 47.4%, improving by 3.7% and 2.6%, respectively, when compared to the optimised conventional diesel combustion (45.7%) and conventional diesel–methanol dual-fuel (46.2%). This improvement was accompanied with a reduction of 37% in nitrogen oxide emissions and little impact on soot emissions in comparison with the conventional diesel combustion.

Investigation to meet China II emission legislation for marine diesel engine with diesel methanol compound combustion technology

In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time, the use of clean and renewable alternative fuel for marine engines is a promising option. In this study, a marine diesel engine, which was modified to run in diesel methanol compound combustion (DMCC) mode, was investigated. After the diesel injection parameters were calibrated, and combined with a sample after-treatment device DOC (diesel oxidation catalyst), the engine could meet the requirements of China II legislation. The overall MSP (methanol substitute percent) reached 54.1%. The value of each pollutant emission was much lower than that in China II emission legislation, and there was almost no methanol and formaldehyde emissions. When methanol was injected into the inlet manifold, the intake air temperature decreased a lot, as well as the exhaust gas temperature, which were beneficial to increase engine thermal efficiency and improve engine room environment. Compared with the engine running in pure diesel mode, when the engine ran in diesel/methanol dual fuel mode, the combustion phase was advanced, and the combustion duration became shorter. Therefore, the engine thermal efficiency increased, and fuel consumption decreased significantly.

Exergy loss analysis on diesel methanol dual fuel engine under different operating parameters

In order to reveal the mechanism of high thermal efficiency of diesel methanol dual fuel (DMDF) engine, the exergy loss of DMDF engine under different operating parameters is investigated by using experimental and calculative methods based on the second law of thermodynamics. It has been found that DMDF has lower heat transfer exergy loss under all engine loads due to the high latent heat of vaporization of methanol which reduces the temperature in-cylinder. The exhaust exergy loss of DMDF under high load is relatively low compared with that of pure diesel fuel, while it is opposite to that under medium-low load. This is due to the influence of different temperatures on the incomplete combustion of methanol, which also indicates the main cause for the high thermal efficiency of DMDF under high load. Then studies on exergy analysis of DMDF under different temperatures were carried out. The studies covers the effect of intake air temperature on exergy efficiency, the heat transfer exergy loss and the exhaust physical exergy loss increase with rising intake air temperature as well. The results shows that the exhaust chemical exergy loss decreases significantly with the increase of intake air temperature and higher intake air temperature helps to improve exergy efficiency. Additionally, it is concluded that higher methanol temperature and cooling water temperature can improve exergy efficiency by decreasing exhaust exergy loss and combustion irreversible exergy loss. Finally, some feasible measures are proposed to further improve DMDF engine’s performance.

Experimental study of the active and passive regeneration procedures of a diesel particulate filter in a diesel methanol dual fuel engine

The diesel methanol dual fuel (DMDF) technology has been used in diesel engines to reduce the nitrogen oxides (NOX) and particulate matter (PM) emissions in past years. A combination of a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF) is applied on DMDF engines to meet severer emission standards in this study. The DOC was modified to produce adequate nitrogen dioxide (NO2) in the presence of the high hydrocarbon and carbon monoxide emissions formed by DMDF mode. During tests, the effect of methanol substitution ratio (MSR) and DOC inlet temperature on DOC performance was studied. Moreover, the effect of MSR on the active and passive regeneration of DPF was investigated. Results show that at high DOC inlet temperatures (>190 °C), the DMDF mode combined with DOC achieves the high DPF inlet temperatures and the high NO2/PM ratio, which is benefit for passive regeneration. During active regeneration, the initial regeneration temperature, the fuel penalty and the emissions of PM, particulate number (PN), NO2 and carbon dioxide (CO2) after the DPF at MSR40 are lower than those at MSR0. The emissions of methanol (CH3OH) and formaldehyde (HCHO) after the DPF at MSR40 are higher than those at MSR0. During passive regeneration, the regeneration rate at MSR40 is higher than that at MSR0, as well as the emissions of PN, CH3OH and HCHO after the DPF. While the NO2 and CO2 emissions after the DPF at MSR40 are lower than those at MSR0.