Methanol Injection Research Articles

Hydrogen enrichment in methanol SI engine at varying injection timing during compression stroke

This study investigates the effect of hydrogen enrichment in a direct-injected methanol-fuelled SI engine, with combustion and emission performance analysed by varying the methanol injection timing from 150° to 60° CA bTDC. A three-dimensional computational fluid dynamic model of the hydrogen-enriched methanol engine was developed to predict the engine performance, in-cylinder, and emission characteristics. The numerical model was solved using three-dimensional Reynolds-Averaged Navier Stokes, the RNG k-epsilon model for turbulence, the O'Rourke and Amsden sub-model for heat transfer, the extended Zeldovich mechanism for nitric oxide emissions, and the Hiroyasu-NSC model for soot emissions. The results indicated that retarding the injection timing resulted in a decrease in the indicated specific CO and soot emissions along with a rise in the indicated specific NOx emissions. Furthermore, hydrogen enrichment with methanol enhanced the hydroxyl radical concentration, reduced the combustion duration, reduced also the indicated specific CO and soot emissions while increasing the indicated specific NOx emissions. The study indicates that hydrogen enrichment could extend the late injection timing limit of methanol by enhancing fuel-air mixing, which improves and controls the combustion process more effectively.

Chemical reaction network analysis on N2O emissions control strategies of ammonia/ methanol Co-combustion

As a kind of substitute fuel of hydrocarbon fuel, ammonia has gained increasing attention for its potential to reduce carbon emissions. Blending with carbon-neutral methanol is expected to deal with the slow flame speed of ammonia. Nevertheless, the emission of N2O, a byproduct of ammonia combustion, would undermine the carbon reduction benefits due to its high global warming potential. This study employed Chemkin to construct a Chemical Reaction Network (CRN) model to analyze the reaction kinetics of ammonia combustion when blended with a small amount of methanol. It finds that the increases in the methanol blending ratio, pressure, and temperature can reduce greenhouse gas emissions effectively. Further analysis indicates that pressure and temperature have distinct effects on the emission mechanisms of N2O and NO. Increasing the combustion pressure weakens the chain reactions, thereby reducing the formation of both NO and N2O; the increase in initial temperature raises NO emissions, but also promotes the decomposition of N2O due to the abundance of H in the post-combustion phase. Optimizing post-combustion efficiency and controlling the formation of NO are crucial for N2O emission control. Thus, a staged methanol injection strategy is proposed, where early injection reduces NO emissions and late injection facilitates the decomposition of N2O.

Modelling the evaporative cooling effect from methanol injection in the intake of internal combustion engines

Renewable methanol is one of the most promising alternative fuels for internal combustion engines. However, its much higher latent heat of vaporization compared to traditional fossil-based hydrocarbon fuels poses new challenges. On both spark-ignition (SI) engines and dual-fuel (DF) engines, methanol can be introduced through injectors installed in the intake path, with its evaporation then causing a cooling effect to the intake air flow. While this is beneficial in mitigating knock with both SI and DF operations, it could potentially lead to cold-starting issues in SI engines and incomplete combustion in DF engines. To properly model the in-cylinder behaviour, the mixture temperature after methanol injection needs to be accurately predicted. A simple yet effective methanol evaporation model based on the liquid droplet and film evaporation mechanisms is thus proposed here to quantify the evaporative cooling effect from methanol injection. The model first treats the methanol spray as a group of droplets with identical size, and after reaching the wall the model assumes that the remaining methanol forms a thin liquid film. The evaporation rates and the consequent temperature drops of these two modes are calculated separately. The calculation results indicate that only a negligible amount of methanol evaporates as droplets, with the predicted temperature drops agreeing well with the validation datasets when taking only the film evaporation into account. The key factor for this good agreement is that the balance between the heat and mass transfer needs to considered when evaluating the surface temperature of a liquid methanol film. The proposed model also suggests that the droplet evaporation can be greatly improved with an injection angle nearly parallel to the air flow, or a finer initial droplet size. Both measures are more effective than increasing the air temperature before injection.

Comparison of methanol and ethylene glycol effectiveness as chemical inhibitors in the prevention of gas hydrates in well testing barge DT-05 well Z Mahakam field

Gas hydrate is one of the production problems that are often encountered in the management of natural gas wells. Well Z is a natural gas well in the Mahakam field which routinely be tested periodically to determine the ability of flow rate and the production parameters using well testing barge. However, there are often for the formation of gas hydrate formed in several test components in well testing barge. This study aims to determine the effectiveness use of 2 inhibitor chemicals, which are methanol and glycol in handling gas hydrate in the testing barge. Natural gas flow originating from wellhead / upstream 5 MMScfd and temperature 122 °F and the operating pressure 2187 psia. From the simulation results, gas hydrate will form at 46.33 °F and it is obtained that the gas hydrate formation was predicted at the choke manifold. Fluid stream passing through the choke manifold had decreased the pressure into 254 psi and there is also a decrease in temperature from 122 °F to 41.88 °F. Methanol injection develops free of potential hydrates to form in flowlines. The temperature at which hydrates are formed changes to 33.88 °F. In the other hand, after Ethylene glycol injection in flowline, hydrates formation temperature dropped to 0.48 °F. From these results it can be resumed that the application of Ethylene Glycol injection on the process is more effective lowering the temperature of the formation of hydrates in well testing barge.

Optimization of methanol/diesel dual-fuel engines at low load condition for heavy-duty vehicles to operated at high substitution ratio by using single-hole injector for direct injection of methanol

Methanol, as a low-carbon and easily synthesizable fuel, is one of the promising directions for future internal combustion engine (ICE) fuels. However, methanol/diesel engines with high energy substitution ratios exhibit a significant drawback at low loads, namely poor fuel economy, which seriously hinders the development of dual fuel engines. Therefore, this paper conducts an optimization study on the combustion strategy of methanol/diesel in heavy-duty vehicle engines under high energy substitution ratios (70 %) and low loads. Innovatively combines single-hole injection with the direct dual fuel stratification (DDFS) technology. By coupling the longer injection duration of a single hole with higher injection pressure, and tailored combustion strategy adjustments, successfully achieving the goal of optimizing low-load methanol dual fuel engines. The research results indicate that when employing a methanol single-stage injection strategy, setting the start of diesel injection (SODI) of −25°CA after top dead center (ATDC) effectively enhances the combustion efficiency of methanol/diesel, especially when combined with a strategy that the start methanol injection (SOMI) is of −23°CA ATDC. This combination can boost the gross indicated thermal efficiency (ITEg) to 51.95 %. The research on utilizing a methanol two-stage injection strategy found that increasing the methanol premixing appropriately, within the engine's safe range, can effectively enhance ITEg. Specifically, with the methanol pre-injection ratio (MPR) of 10 % and the methanol two-stage injection interval (MII) of 20°CA, ITEg can be improved to 52.07 %. However, excessively of premixing can lead to premature combustion, causing an increase in negative work during the compression stroke and consequently reducing ITEg. This study has unveiled effective solutions for the application of methanol/diesel DDFS technology in the automotive engine field. It offers insights into the selection and optimization of methanol injectors and provides theoretical support and practical references for achieving clean and efficient combustion in engines.

Experimental study on the effects of water addition in methanol on the performance of diesel-methanol diffusion combustion on a high-speed engine

Methanol is regarded as a low-carbon renewable fuel which is friendly to the environment. For purpose of investigating the impact of water introduction in methanol on diesel-methanol diffusion combustion, experimental tests were performed on a refitted dual-fuel high-speed diesel engine test bench. This research compared the differences between diesel-methanol diffusion combustion (DMDC) mode and diesel-hydrous methanol diffusion combustion (DHMDC) mode with a water mass content of 20%. The tests were performed by maintaining the engine speed of 3000 rpm and varying engine load as well as methanol injection timing (MIT). The results indicate that the heat release process in DHMDC mode begins later but is more rapid and concentrated compared to DMDC mode. The addition of 20% water in methanol does not significantly decreases the peak average in-cylinder temperature. However, it decreases the NOx emissions by up to approximately 40%. Water introduction leads to higher CO and THC emissions in DHMDC mode, but the retardation of MIT helps mitigate the increase in CO and THC emissions. The exhaust losses in DHMDC mode decrease by about 5%–8%, while the heat transfer losses increase by over 20%, resulting in a lower indicated thermal efficiency (ITE) in comparison with DMDC mode. The effects of the 20% water addition in methanol are sensitive to changes in engine load and MIT. Higher engine load and appropriately retarded MIT facilitate more efficient and cleaner combustion in DHMDC mode.

Simultaneous quantification of 4-hydroxytamoxifen and hesperidin in liposomal formulations: Development and validation of a RP-HPLC method

Breast cancer treatment options are diverse, with tamoxifen commonly used as a selective estrogen receptor modulator (SERM) for hormone receptor-positive breast cancer. However, tamoxifen can have adverse systemic effects. Local transdermal therapy offers a potential solution by delivering the drug directly to the breast and minimizing systemic exposure. Hesperidin, a flavonoid, exerts synergistic effects when combined with anticancer agents. This combination therapy may be a more effective approach to breast cancer management. Analytical methods have been developed to quantify 4-Hydroxytamoxifen (4-HT) and hesperidin separately; however, no method currently exists for their simultaneous quantification in pharmaceutical formulations. This study aimed to develop and validate a reverse-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous quantification of 4-HT and hesperidin in liposomal formulations. A Design of Experiments (DoE) approach was employed using a Box-Behnken design (BBD) to optimize the RP-HPLC method. BBD allowed for a reduction in the number of required tests by creating a statistical model to estimate the significance of various factors and interactions. The methanol concentration, flow rate, and injection volume were considered as independent variables for optimization. A mobile phase (90:10 ratio of methanol: 0.1% v/v orthophosphoric acid) with a flow rate of 0.4 mL/min, and an injection volume of 10 μL was selected as optimized chromatographic condition. 4-HT showed a retention time (Rt) of 5.05 min and hesperidin showed an Rt of 7.11 min using an optimized analytical method and was detected at 275 nm. The developed RP-HPLC method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines, confirming its accuracy, precision, linearity, selectivity, and robustness. The validated method was then successfully applied to determine the entrapment efficiency and permeation of 4-HT and hesperidin into loaded liposomes. This study fills a gap in the literature by providing a simple and reliable RP-HPLC method for the simultaneous quantification of 4-HT and hesperidin in liposomal formulations.

Investigating the influence of varying split injection profiles on stability of diesel engine operated under partially premixed mode with methanol

The present study explores the prospects of operational stability of dual fuel operation comprehensively, considering that; methanol and diesel are of two different kinds which exhibit different combustion processes. To this effect, investigating the stability of engine operation under such condition becomes important. In this investigation, the harshness of the operation and the non-repeatability of the combustion cycles are examined, which have been identified as the major stability indicator in many studies. Such stability indices are characterized in this study through a comprehensive set of parameters, including of maximum pressure rise rate (ROPRmax) and coefficient of variation of indicated mean effective pressure (COVIMEP); and of peak pressure (COVPP) and crank angle of 50% mass fraction burn (COVCA50). The experimental investigation is carried out under a split injection strategy by varying injection timings as well as injection mass percentages at predefined methanol injection durations. It is shown that the partially premixed mode under the split injection strategy exhibits significant potential in reducing the harshness of operation indicated by lower peak pressure rise and increasing the repeatability of the combustion cycles implied by the substantially lower scores of the considered parameters for mapping stability.

Analysis of the application of a chemical method for preventing hydrate formation on the example of the Novo-Chaselskoye field

In the presented work, the possibility of preventing the formation of gas hydrates at the Novo-Chaselskoye field by means of metered methanol injection is considered. The current state of field development and information on reserves are presented. A method for calculating the amount of an inhibitor (methanol) required to prevent hydrate formation for Cenomanian gas is presented. As a result of the study, the amount of methanol consumption for hydrate-free well operation was calculated, the conditions and places of possible hydrate occurrence were analyzed, and the required amount of hydrate formation inhibitor was calculated to be supplied to the wellhead to prevent hydrate precipitation.

Analysis of sensitivity to hydrate blockage risk in natural gas gathering pipeline

During the operational process of natural gas gathering and transmission pipelines, the formation of hydrates is highly probable, leading to uncontrolled movement and aggregation of hydrates. The continuous migration and accumulation of hydrates further contribute to the obstruction of natural gas pipelines, resulting in production reduction, shutdowns, and pressure build-ups. Consequently, a cascade of risks is prone to occur. To address this issue, this study focuses on the operational process of natural gas gathering and transmission pipelines, where a comprehensive framework is established. This framework includes theoretical models for pipeline temperature distribution, pipeline pressure distribution, multiphase flow within the pipeline, hydrate blockage, and numerical solution methods. By analyzing the influence of inlet temperature, inlet pressure, and terminal pressure on hydrate formation within the pipeline, the sensitivity patterns of hydrate blockage risks are derived. The research indicates that reducing inlet pressure and terminal pressure could lead to a decreased maximum hydrate formation rate, potentially mitigating pipeline blockage during natural gas transportation. Furthermore, an increase in inlet temperature and terminal pressure, and a decrease in inlet pressure, results in a displacement of the most probable location for hydrate blockage towards the terminal station. However, it is crucial to note that operating under low-pressure conditions significantly elevates energy consumption within the gathering system, contradicting the operational goal of energy efficiency and reduction of energy consumption. Consequently, for high-pressure gathering pipelines, measures such as raising the inlet temperature or employing inhibitors, electrical heat tracing, and thermal insulation should be adopted to prevent hydrate formation during natural gas transportation. Moreover, considering abnormal conditions such as gas well production and pipeline network shutdowns, which could potentially trigger hydrate formation, the installation of methanol injection connectors remains necessary to ensure production safety.

Effects of Injection Parameters and EHN Mixing on the Combustion Characteristics of Fueling Pure Methanol in a Compression Ignition Engine

As one of the most ideal alternative fuels for internal combustion engines, methanol can achieve near-zero carbon emissions. The main problem of methanol application in compression combustion engines is the phase lag caused by its poor combustion characteristics, but under low load conditions, the fuel activity can be improved by adding the cetane number improver EHN (Isooctyl nitrate), and the dependence on intake heating can be reduced to a certain extent. Based on a three-dimensional CFD simulation, the effects of methanol injection parameters and the addition of EHN on the combustion characteristics of a four-stroke exhaust turbocharged diesel engine were studied in this paper. With or without EHN, the increase in injection pressure and the advance in injection timing lead to an increase in the peak temperature, pressure, and heat release rate, as well as a shortening of the combustion duration. Adding EHN witnesses reduced requirements for methanol ignition, including a decreased peak temperature, pressure, and heat release rate, a significantly shortened ignition delay period, and an extended combustion duration, which thus results in a reduced indicated thermal efficiency. This study innovatively develops a 3D model of a compression combustion engine applicable to in-cylinder direct injection pure methanol fuel and EHN under small load conditions, which provides a reference for future research and development of small-load pure methanol compression combustion engines and has certain guiding significance.

Investigation on formaldehyde generation characteristics and influencing factors of PODE/methanol dual-fuel combustion mode.

Polyoxymethylene dimethyl ether (PODE) and methanol are important low-carbon substitutable fuels for reducing carbon emissions in internal combustion engines. In the research, the impacts of methanol ratio, injection timing, and intake temperature on HCHO generation and emission were investigated using both engine tests and numerical simulations. Results suggest that an increase in methanol ratio suppresses auto-ignition tendency of PODE, leading to the increase of ignition delay period, pressure peak, and heat release rate peak inside the cylinder. The decrease in in-cylinder combustion temperature contributes to an increase in HCHO emission due to partial oxidation of methanol in the cylinder and exhaust pipe. While the injection timing is gradually postponed from -10 °CA ATDC to 2 °CA ATDC, in-cylinder high-temperature area decreases, the quantity of unburned methanol increases, but part of HCHO is converted to HCO due to H radical influence, resulting in 72% increased HCHO emission. With the increment of intake temperature, the oxidation and decomposition of in-cylinder methanol accelerate, leading to an improvement in combustion stability, more uniform temperature distribution, and a decrease in unburned methanol, which results in lower HCHO emission. When the intake temperature is rose from 30 to 60 °C, HCHO emission decreases by 11.2%.

Computational study of added H2 impacts on mixture formation, OH radical and unregulated emissions of spark-ignition methanol engine under various boundary parameters

Numerical simulations of hydrogen (H2) impacts on mixture formation, OH radical generation, and formaldehyde (HCHO) and unburned methanol (CH3OH) emissions of spark-ignition (SI) methanol engine based methanol late-injection strategy under different methanol injection timings (MIT), ignition timings (IT), excess air ratios (λ) and added H2 ratios (RH2) boundary parameters were conducted. The simulation results show that the ideal methanol concentration distribution is obtained at the MIT = 85°CA BTDC. The OH radical plays a dominant role in methanol oxidation. The OHPMF (peak OH radical mass fraction) of RH2 = 9 % ≫ OHPMF of RH2 = 6 % > OHPMF of RH2 = 3 % > OHPMF of RH2 = 0 % at MIT = 85°CA BTDC. Compared with IT and λ, the RH2 is more decisive for the generation of OH radical. The HCHO is a major intermediate and an important unregulated emission of methanol engine. In the initial stage of methanol reaction, added H2 can accelerate the generation of OH radical, further promote the oxidation of methanol, and greatly raise the generation of HCHO. The peak HCHO mass fraction increases with the increase of RH2. At MIT = 85°CA BTDC and exhaust valve opening, the HCHO emission of RH2 = 3 %, 6 %, and 9 % is approximately 51 %, 76.5 % and 89.4 % lower than that of RH2 = 0 %, respectively. The generation and post-oxidation of HCHO mainly depended on average in-cylinder temperature. There is a lowest CH3OH emission at MIT = 85°CA BTDC, IT = 28°CA BTDC, λ = 1.4 and pure methanol. At MIT = 85°CA BTDC, λ = 1.4 and exhaust valve opening, the CH3OH emission of RH2 = 3 %, 6 %, and 9 % is approximately 52.8 %, 75.5 % and 92.5 % lower than that of RH2 = 0 %, respectively.

Effects of Methanol Addition on the Combustion Process of the Methanol/Diesel Dual-Fuel Based on an Optical Engine

The combustion process of traditional diesel engines is mainly determined by the injection timing of diesel. There is a trade-off relationship between the soot and NOx (nitrogen oxides) during this combustion process, making it difficult to reduce these two emissions simultaneously. The use of methanol can not only solve the above problem, but also replace some fossil fuels. However, the effects of methanol injection into the intake duct on the flame propagation in diesel/methanol dual-fuel engines is not yet clear, and there is relatively little research on it. The effects of methanol addition on the combustion process of diesel/methanol dual fuel (DMDF) were achieved based on a modified optical engine in this paper. One injector is installed on the intake inlet to inject methanol, and the other injector is installed in the cylinder to inject diesel in two stages before the top dead center of compression. There are three tests conducted separately in this paper. Firstly, the effects of the methanol ratio (40%, 50%, 60%, and 70%) on the combustion process are investigated, with the total heat remaining unchanged. Secondly, the effects of the pre-injection mass of diesel (20%, 30%, 40%, and 50%) on the combustion process are investigated, which keeps the total diesel mass unchanged. Finally, the effects of the total mass of diesel on the combustion process are investigated while maintaining the mass of methanol unchanged. The dual-fuel combustion process is recorded by a high-speed camera. A combustion analyzer and other equipment were used to analyze the combustion. The results showed that CA10 is delayed, the pressure and the heat release rate (HRR) are reduced, and the number of pixels of the KL factor (KL) decreases significantly with the increasing methanol ratio. CA10 and CA50 are advanced, the pressure and HRR decrease, and the KL increases when the mass of pre-injected diesel increases. CA10 and CA50 are advanced, respectively, and CA90 is postponed due to the increase in diesel mass. The pressure and HRR increase, and the KL increases when the total mass of diesel increases.

Experimental Investigation on the Effects of Direct Injection Timing on the Combustion, Performance and Emission Characteristics of Methanol/Gasoline Dual-Fuel Spark Turbocharged Ignition (DFSI) Engine with Different Injection Pressures under High Load

The exceptional properties of methanol, such as its high octane number and latent heat of evaporation, make it an advantageous fuel for efficient utilization in dual-fuel combustion techniques. The aim of this study is to investigate the effect of direct methanol injection timing on the combustion, performance and emission characteristics of a dual-fuel spark ignition engine at different injection pressures. We conducted four different direct injection pressure tests ranging from 360° ahead to 30° CA ahead at 30° CA intervals. The experimental results indicate that regardless of the injection pressure, altering the methanol injection timing from −360° to −30° CA ATDC leads to distinct combustion behavior and changes in the combustion phase. Initially, as the injection timing is delayed, the combustion process accelerates, which is followed by a slower combustion phase. Additionally, the combustion phase itself experiences a delay and then advances. Regarding performance characteristics, both the brake thermal efficiency (BTE) and exhaust gas temperature (EGT) exhibit a consistent pattern of first increasing and then decreasing as the injection timing is delayed. This suggests that there is an optimal injection timing window that can enhance both the engine’s efficiency and its ability to manage exhaust temperature. In terms of emissions, there are different trends in this process due to the different conditions under which the individual emissions are produced, with CO and HC showing a decreasing and then increasing trend, and NOx showing the opposite trend. In conclusion, regardless of the injection pressure employed, adopting a thoughtful and well-designed injection strategy can significantly improve the combustion performance and emission characteristics of the engine. The findings of this study shed light on the potential of methanol dual-fuel combustion and provide valuable insights for optimizing engine operation in terms of efficiency and emissions control.

Influence of water‐methanol injection and turbocharging on the performance of a hydrogen‐fueled spark ignition engine

AbstractThis article presents a study that compares the performance and emission characteristics of a four‐stroke, four‐cylinder spark ignition (SI) engine fueled by gasoline and neat hydrogen. The engine was equipped with turbocharging to optimize ignition timing for power boosting and vaporized water–methanol injection to reduce emissions. Engine tests were conducted at speeds ranging from 2000 to 6000 rpm, with a fixed intake pressure and varying quantities of hydrogen and spark advance timings. The study compared the results of non‐turbocharged and turbocharged engines with water–methanol injection in terms of combustion, performance, and emissions. The findings showed that the turbocharged water–methanol hydrogen operation had a higher brake thermal efficiency (BTE) than its counterpart, while the brake power of the hydrogen engine operation increased with turbocharging but slightly decreased with water–methanol injection. Additionally, volumetric efficiency improved by 7% for turbocharged and 4% for water‐injected hydrogen engine operation compared to the counterpart. The cylinder pressure for turbocharging with water–methanol operation yielded 16.32% higher compared with counterpart gasoline engine operation. Finally, nitrogen oxides (NOx) emissions were reduced with turbocharging and water–methanol injection compared to the counterpart non‐turbocharged hydrogen engine operation.

Effect of direct methanol injection based on low-flow injector on knock of gasoline engine under heavy load condition

Under appropriate strategies, direct methanol injection can suppress the knock effectively. In this paper, methanol was injected as an anti-knock agent by modified low-flow direct injectors into the cylinder of a high-load port injection gasoline engine. The effects of methanol injection timing and methanol ratio on knock suppression were investigated. The knock intensity (KI), knock probability, and auto-ignition timing were used as the primary basis for quantifying the knock. The results show that methanol injection timing has a significant impact on combustion. Maximum knock suppression can be achieved when methanol is injected near the bottom dead center. The too-early and too-late injections will affect the knock suppression. There was an apparent knock phenomenon when methanol was injected near the end of the compression stroke. When the ratio of methanol is meager, methanol will instead increase the intensity of the knock. As the methanol ratio rises, the knock is gradually and effectively suppressed. There is a specific methanol ratio beyond which higher methanol ratios do not significantly increase the knock suppression effect. When methanol was injected late in the compression stroke, low methanol ratios did not seriously increase the knock intensity, but high methanol ratios did not eliminate the knock either.

Effect of nozzle geometry on combustion of a diesel-methanol dual-fuel direct injection engine

A three-dimensional model of fuel combustion in a diesel-methanol dual-fuel direct injection engine is constructed to study the effect of nozzle geometry. The model includes two nozzles, one for diesel injection and one for methanol injection. Based on the geometric modeling and empirical formulas for the nozzle, the influence of fuel flow in the nozzle on fuel combustion in the cylinder is calculated. In the geometric modeling, the influences of the R/D and L/D parameters on the effective injection radius of the nozzle, the spray velocity at the outlet, and the fuel’s Sauter mean diameter in the cylinder are analyzed. For the flow simulation inside the nozzle using empirical formulas, the effects of discharge coefficient and spray angle are analyzed. The simulation results show that a larger R can increase engine power. Both R and L have an impact on the formation of pollutants. The discharge coefficient has a greater impact on the performance of the engine than the spray angle, and a suitable spray angle is around 13°. The effects of dual-fuel nozzles with different diameters on combustion temperature and pollutant emissions in the engine cylinder are analyzed through experiments.

Experimental study on the effect of injection strategies on the combustion and emissions characteristic of gasoline/methanol dual-fuel turbocharged engine under high load

This study aims to investigate the impact of methanol direct injection strategy on the combustion and emission characteristics of a dual-fuel turbocharged engine running under high load of 1500 rpm. Five methanol injection timings ranging from −330° CA (crank angle) to −60° CA ATDC (after top dead center) were tested under four different methanol energy substation ratios. Based on the experimental results, a suitable injection timing was selected to study the effect of methanol energy substation ratio. The results showed that different injection timings had varying effects on engine combustion and emission characteristics. End of injection timing of methanol (EOI) at −180° CA ATDC resulted in fuller atomization of methanol, which delayed combustion and reduced the combustion rate, with the lowest knock intensity and highest indicated mean effective pressure. However, this timing also had the highest emissions of NOx. Further experiments were conducted at EOI = −180° CA ATDC under eight different energy substation ratios. The results demonstrated that adjusting the injection strategy of methanol can effectively change the engine's performance. The optimal injection strategy was found to be EOI = −180° CA ATDC and an energy substation ratio range of 4.6%–8.9%. This research provides valuable insights into the use of methanol as a fuel and its impact on engine characteristics.

Numerical study of injection strategies for marine methanol/diesel direct dual fuel stratification engine

To explore the application potential of renewable methanol and direct dual fuel stratification (DDFS) technology in marine internal combustion engines, this study conducted a fuel injection strategy research based on performance optimization for a marine methanol/diesel DDFS engine under high methanol substitution rate (95%). The results show that the fuel mixing process plays a crucial role in methanol/diesel DDFS engine combustion state switching. Premature methanol injection under methanol single-stage injection strategy causes ringing intensity (RI) to exceed the engine limit. Additionally, when start of diesel injection (SOID) occurs earlier than start of methanol injection (SOIM), the shorter methanol/diesel injection interval (MDI) leads to the deterioration of diesel premixed combustion for reason of methanol spray interference. Therefore, adopting an injection strategy with SOID earlier than SOIM under methanol single-stage strategy combined with an appropriately extended MDI achieves better comprehensive engine performance. Further optimization of methanol/diesel DDFS engine using a methanol two-stage injection strategy shows that the methanol two-stage injection strategy provides better fuel economy while maintaining acceptable RI. By increasing the methanol pre-injection ratio (MR1) and optimizing the methanol two-stage injection interval (MMI), the engine economy was further enhanced. Compared with the methanol single-stage injection strategy, the optimized methanol two-stage injection strategy reduced equivalent indicated specific fuel consumption (EISFC) by 3.95%. However, it should be noted that the combustion completeness under the methanol two-stage injection strategy decreased, leading to higher emissions of HC, CO and soot. On the other hand, this strategy resulted in lower NOX emissions due to more sufficient premixed combustion.