Performance Of Dual Fuel Engine Research Articles

Performance and environmental sustainability studies on a dual-fuel IC engine working with producer gas of variable calorific values from rural biomass.

Decentralized power generation using renewable gaseous biofuels faces challenges due to their inconsistent quality and availability. Mixing producer gas (PG) with diesel as a secondary fuel is a promising option, but the non-stable calorific value (CV) of PG from different biomasses poses a serious problem for the efficient operation of a dual-fuel engine. This study aims to examine how the CV of PG from various biomasses affects a 3.75-kW dual-fuel IC engine's performance. The experimental facility, which has a dual-fuel engine and a 115-kW thermal gasifier, tested the blends of diesel and PG from different biomasses. We chose biomass based on its availability and PG's CV of 3.4, 4.4, 5.2, and 6.3MJ/Nm3. For this range of CV, the efficiency, energy consumption, and fuel replacement of a dual-fuel engine vary between 20.9 and 26.6%, 17.3 and 13.5MJ/kWh, and 10.8 and 76.9%, respectively. Furthermore, the blend with the maximum CV of PG had a 69.64% lower specific diesel consumption and an 86% higher diesel replacement rate than the blend with the lowest CV of PG. In terms of emission characteristics, the comparison showed a 2.02-7.06% reduction in NOx and a 4.05-55.6% increase in hydrocarbons (HCs) for the tested conditions. The overall observations demonstrated that a significant enhancement in a dual-fuel engine's performance is possible with a higher CV of PG. However, the emissions trade-offs demand additional optimization studies, as well as case-based research, in order to integrate renewable energy and emission management in smaller-scale applications across more geographies.

Decarbonization strategies in the maritime industry: An analysis of dual-fuel engine performance and the carbon intensity indicator

This study is based on detailed data from 11 sea voyages over three years to determine the impact of liquefied natural gas (LNG) use on the decarbonization pathway in maritime transportation. The research detailed the vessel's daily fuel consumption, CO2 emission inventories, and Carbon Intensity Indicator (CII). The decision tree method used to evaluate this complex dataset highlights the possible contributions of LNG to maritime energy efficiency and sustainability. While the findings show that LNG reduces CO2 emissions by around 30 %, it is insufficient to meet the International Maritime Organization's (IMO) 2050 targets. The study concludes that LNG should be an important transition fuel until the mid-2030s. However, the maritime sector needs multi-pronged strategies such as technological innovations, stringent regulations and sectoral collaborations to achieve a decarbonized future. This research provides a comprehensive analysis assessing the potential of LNG to achieve the IMO 2050 targets in the context of maritime decarbonization strategies.

Desirability-based optimization of dual-fuel diesel engine using acetylene as an alternative fuel

The study examined the dual-fuel engine performance employing acetylene gas as primary fuel and diesel as pilot fuel. The engine's operational parameters were adjusted using the Box-Behnken design, and the results were recorded. The best operating settings were yielded as 81.25 % engine load, 4.48 lpm acetylene gas flow rate and the compression ratio were 18. At this optimized setting the BTE was 27.1 % and the engine emitted 360 ppm of NOx, 56.2 ppm of HC, 104 ppm of CO. The experimental data at optimized setting was compared to the optimized results, and the percentage of errors was within 7 %. Two advanced machine learning methods, LightGBM and Tweedie, were used to predict engine efficiency and emissions. Tweedie-based models had an R2 value of 0.89–1, while LightGBM-based models had an R2 value of 0.38–1. The mean squared error was 0.24–45.04 for Tweedie-based models and 8.5 to 153.89 for LightGBM-based models. On the basis of R2 and MSE, it was observed that Tweedie was superior at making predictions than LightGBM. The study demonstrated the efficient functioning of a dual-fuel engine using acetylene as an alternative fuel for increased performance and lower emissions.

Green Energy from Palm Kernel Shell Gasification – dual fuel engine performance analysis

<span lang="EN-US">Electricity generation in Indonesia is mainly generated from non-renewable fuels. Based on these problems, this research utilizes palm kernel shells to be converted into producer gas as secondary fuel for a 5 kW diesel engine. Through a gasification process equipped with a cooling and gas cleaning system, low tar gas is fed to the diesel engine with variations of gas flow rate ratio to combustion air. A dummy load is installed to investigate the effect of load on diesel consumption. The diesel engine vibration increases due to using two fuel types was measured by installing a vibration meter. The research results show that the higher the load and the greater the ratio of producer gas injected, the less diesel consumption. At a gas ratio of 4:1 and an increase of load from 1 to 5 kW, the diesel fuel flow rate reduces by 25 - 31%. The most significant reduction in diesel consumption occurred at a load of 5 kW, valued at 38.49%. On the other hand, increasing the gas ratio causes an increase in diesel engine vibration. The research results showed an increase in engine vibration of 5.84% - 10.25%. The largest vibration was recorded at a load of 5 kW with a value of 92.4 m/s<sup>2 </sup> </span>

Effect of Injection Timing on the Dual Fuel Engine Performance Operated with Hydrogen and Nano-Biodiesel Blends

In the current work, effect of nano-biodiesel blends and injection timing on the performance of hydrogen fueled dual fuel (DF) engine is presented. Hydrogen flow rate is maintained constant with a flow rate of 0.15 kg/h. For this B20 and nano-blends of Nigella sativa oil methyl ester (NLSTVAOME) and Jack fruit seed oil methyl ester (JKFSOME) fuel combinations are used. Nano-blends of respective B20 biodiesels are prepared using graphene amine (GA) nanoparticles with varied proportions ranging from 60 to 100 ppm using probe sonication method. Stabilization of the nano-blends are ensured with reference to quantity of nanoparticle, surfactant SDS (Sodium Dodecyl Sulfate) used and sonication time. Addition of the nanoparticles in the B20 biodiesel blends till 80 ppm showed considerable improvements on the performance of diesel engine with single fuel operation due to improved combustion compared to B20 biodiesel blends. Beyond 80 ppm the performance deteriorated due to non-homogeneous mixtures of nano-biodiesel blends. Injection timing (IT) for the modified DF engine IT is varied from 19 to 31oBTDC in steps of 4oBTDC. Further advancing the IT from 19 to 27oBTDC showed improved dual fuel engine performance with B20+GA80 blends of both biodiesels along with hydrogen induction when compared to B20 operation. Further mixing of air-hydrogen in the inlet manifold of dual fuel engine is studied using CFD analysis for varied hydrogen flow rates ranging from 0.10 to 0.2 kg/h in steps of 0.05 kg/h.

Syngas-diesel dual-fuel engine performance using H2/CO top gases from the steel industry furnaces

This study aims to utilize H2-CO-rich waste gases as an alternative energy source for power generation in a dual-fuel engine setup, where diesel is used as an ignition source. A Computational Fluid Dynamics (CFD) model is developed and validated against experimental data using synthesis gas compositions containing H2, CO, CO2, and N2. A chemical kinetics model is integrated to enhance combustion accuracy, combining the diesel_14 and Gri-mech 3.0 sets to compute reactions involving diesel and synthesis gas/flue gases. Following validation, the study analyzes the dual-fuel engine's performance using H2-CO-rich waste gases: Blast Furnace Gas (BFG), Blast Oxygen Furnace Gas (BOFG), and Oxygen Blast Furnace Gas (OBFG) under various inlet temperatures. BOFG with diesel combustion results in higher peak pressure and heat release due to its significant combustible content (75.4 %). When considering BFG with diesel, the SOC occurs at 1⁰ bTDC, whereas for the BOFG and OBFG, ignition commences at 0 TDC. Also, the BOFG's short combustion duration led to an IMEP of 0.88 MPa, enhancing engine capacity than the OBFG and BFG. The exit amount of CO and UHC is higher in the case of BFG compared to the other fuels. Also, BFG exhibits lower MPRR from 0.33 to 0.5 MPa/deg, attributed to its prolonged combustion duration. Higher combustion temperatures increase NOx emissions, notably for BOFG, due to elevated in-cylinder temperatures. In conclusion, this study demonstrates the potential of H2-CO-rich waste gases in dual-fuel engines for power generation, highlighting BOFG's performance advantages while addressing emissions concerns.

Experimental investigation of the effect of ammonia substitution ratio on an ammonia-diesel dual-fuel engine performance

This research experimentally examines an ammonia-diesel dual fuel system, not widely covered in existing literature but acknowledged as an effective approach to reduce engine carbon footprints in alignment with global decarbonization trends, focusing on enhancing understanding of performance, combustion, and emission characteristics vital for designing and optimizing these engines for commercialization. The results indicate that in an ammonia-air mixture atmosphere, diesel undergoes a prolonged ignition process, enhancing the role of premixed combustion. Increasing ammonia substitution at constant speed and load reduces the weight of mixing-controlled combustion, leading to larger areas in the chamber where diesel flames cannot reach. Ammonia oxidation mainly occurs near the diesel flame, as overly lean ammonia-air mixtures fail to sustain stable flame propagation. This results in considerable unburned ammonia emissions, particularly in regions beyond diesel flame reach and engine crevices, adversely affecting combustion efficiency and diminishing the thermal efficiency advantages of such operation. Furthermore, while ammonia combustion contributes to fuel-borne nitrogen oxides (NOx) formation, the overall NOx emissions from ammonia-diesel engines are reduced due to lower combustion temperatures and the deNOx properties of amino groups. However, the partial oxidation of ammonia during the late expansion stroke generates significant levels of nitrous oxide (N2O), a greenhouse gas, in the emissions, counteracting the intended reduction of carbon dioxide. These experimental findings highlight the necessity of focusing on both improving in-cylinder combustion quality and developing effective aftertreatment systems for NH3 and N2O capture, as crucial steps towards enhancing the environmental performance and market viability of ammonia-diesel dual fuel engines.

Construction and verification of dual-fuel engine combustion model

In order to achieve real-time mapping and online optimization of the combustion process of a dual-fuel engine that is in prolonged operation, this paper is the first to combine the Wiebe function with a deep learning neural network to propose a zero-dimensional (0-D) combustion prediction model for a biodiesel-diesel dual-fuel engine. First, the parameters of the double Wiebe functions are calculated by the Pelican Optimization Algorithm (POA), and the operating parameters and Wiebe parameters are used as input and output parameters of neural networks, respectively, to construct parameter identification models. Then, the combustion process is simplified and reconstructed by combining the Wiebe function with the deep learning neural network, and a 0-D prediction model based on the hybrid model-driven and data-driven method is established, which can further obtain combustion results such as cylinder pressure curve and indicated mean effective pressure (IMEP). The results show that the coefficient of determination (R2) value of the dual-fuel engine 0-D prediction model based on the double Wiebe function combined with POA–CNN–Bi-LSTM is 0.9827, and the model has good prediction accuracy and generalization. The development of the combustion model provides reliable numerical model support for the online evaluation and optimization of dual-fuel engine performance.

Effect of flexible camshaft technology on dual-fuel engine performance using phenomenological combustion model

AbstractThe objective of the current study is to investigate the effect of tunable valve timings on the performance and emissions of a dual-fuel marine engine. A simulation model was developed in MATLAB to simulate the valvetrain mechanism. The model generates different valve lift curves depending on the input conditions, and after that, it tests them against any possible collision with the piston. The valid valve lift curves were exported to a two-zone combustion model in AVL CRUISE-M platform. The combustion model depends on the fractal principle and aims to predict the in-cylinder parameters. In addition, it contains sub-models to calculate the ignition delay and emissions formation. Model results were compared against experimental data, as the latter were obtained from a heavy-duty, medium-speed, single-cylinder research engine, which employs natural gas as a main fuel. The results showed good agreement and the model was used for further investigations with other cam pairs. It has been found that the fractal combustion model can effectively represent the combustion behavior in the dual-fuel engine. Furthermore, valve timing has a significant influence on the engine performance and exhaust emissions. Results also revealed that applying Miller cycle can reduce the nitrogen oxides emissions, while the higher valve overlap period had a negative effect on methane slip.

Two Stroke Dual Fuel Engine Performance Analysis on Liquid and Gas Fuel Mode Related to the New Training Demands for Marine Engineers

The present publication shows the results of the planned experiment with a two-stroke dual fuel engine with low pressure of the fuel gas supply in simulated environment on the Wartsila Voyage technological simulator available in Nikola Vaptsarov Naval Academy. The aim of the publication is to facilitate the training process for the specific features in the two different modes of operation of the dual fuel engines on liquid and gas fuel in the context of the turbocharging system condition. The outcomes of the training need to cover the minimum knowledge for safe operation of the ship power plant by the trainees. The subject of the research is a low-speed two-stroke dual fuel engine WIN GD 6X72 DF. The plan of the experiment includes variation in the degree of fouling of the turbine and compressor side of the engine turbocharger ABB A180L and the associated deviations in the engine performance parameters. The variety of performance parameters selected for examination allows the conclusion of several outcomes with technical and educational benefits for the training process. They could be used in the lectures and exercises carried out with the under- and post-graduates in the marine engineering specialty.

Prognostic Metamodel Development for Waste-Derived Biogas-Powered Dual-Fuel Engines Using Modern Machine Learning with K-Cross Fold Validation

Attention over greenhouse gas emissions has driven interest in cleaner energy sources including alternative fuels. Waste-derived biogas, which is produced by the anaerobic digestion of organic waste such as municipal solid waste, agricultural residues, and wastewater sludge, is an intriguing biofuel source due to its abundant availability and promise of lowering emissions. We investigate the potential of waste-derived biogas as an alternative fuel for a dual-fuel engine that also uses diesel as a secondary fuel in this study. We suggest using a modern machine learning XGBoost model to forecast engine performance. Data acquired with thorough lab-based text will be used to create prognostic models for each output in this effort. Control factors impacting engine performance, including pilot fuel injection pressure, engine load, and pilot fuel injection time, will be employed. The effects of these control elements on engine reaction variables such as brake thermal efficiency (BTE), peak pressure (Pmax), nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (UHC) were simulated. The created models were tested using a variety of statistical approaches, including the coefficient of determination (0.9628–0.9892), Pearson’s coefficient (0.9812–0.9945), mean absolute error (0.4412–5.89), and mean squared error (0.2845–101.7), all of which indicated a robust prognostic model. The use of the increased compression ratio helped in the improvement of BTE with a peak BTE of 26.12%, which could be achieved at an 18.5 compression ratio 220 bar fuel injection pressure peak engine load. Furthermore, our findings give light regarding how to improve the performance of dual-fuel engines that run on waste-derived biogas, with potential implications for cutting emissions in the transportation sector.

Performance of Dual-fuel (DF) Engine Powered with the Producer Gas Derived From Sugar Cane Bagasse and Diesel Injection

Renewable and sustainable fuel usage in diesel engines ensures energy security and overseas exchange savings besides conveying both socioeconomic and environmental concerns. This research presents experimental work that has been done on single-cylinder, 4-stroke, diesel engine of direct injection run in DF mode using PG derived from sugar cane bagasse renewable and sustainable fuels. A 45° gas venture is designed and developed to provide a stoichiometric mixture of gas and air entry into the intake manifold of the DF engine during suction stroke. A compressed mixture of air and gas is ignited by injecting diesel into the engine cylinder at 205 bar pressure and at different timings of injection. The effect of timing of injection on the DF engine performance is studied by varying it from 23 to 31obtdc in steps of 4obtdc. Experimental investigation showed that 27oBTC resulted in improved BTE with reduced emissions of hydrocarbon, smoke, and CO while NOx, peak pressure increased. It is noticed that the operation of producer gas lowers the power derating by 20% and the DF engine could run up to 80% load with increased nitric oxide (NOx) emissions. The developed DF engine worked satisfactorily with acceptable performance and emission norms and assisted in partially substituting the fossil diesel fuel with a substitution of 60-70% by the PG operation.

Effect of Injection Advance Angle on the Performance of Butanol-Diesel Dual-fuel Engines

In order to further investigate the performance of the butanol-diesel dual-fuel engine, this paper uses the 4190ZLC-2 marine medium-speed diesel engine as a prototype and establishes a dual-fuel engine high-pressure cycle model using AVL-FIRE simulation software. The injection advance angle was set to 16.6°, 18.6°, 20.6° and 22.6° respectively, and its effect on the performance of the dual-fuel engine was investigated by varying the injection advance angle. The results show that as the injection advance angle increases, the incylinder pressure and temperature also increase. When the injection advance angle is 22.6°CA, compared with the original engine, CO emission is reduced by 16.8%, NO emission is increased by 7.4%, carbon smoke emission is reduced by 16.9%, and the indicated power is 52.6kW, which is increased by 1.8%.

Parametric investigation and optimal selection of the hybrid turbocharger system for a large marine four-stroke dual-fuel engine

• Thermodynamic modelling of large marine dual fuel engine with hybrid turbocharger. • Parametric investigation to identify influence on the engine performance and emissions. • Hybrid turbocharger rated power optimal selection for the considered annual profile. • Installation of a hybrid turbocharger leads to 2–4% surplus energy production. Hybrid turbochargers can become an attractive solution for new built and retrofitted ship power plants, as their use can result in increasing the plant efficiency and reducing emissions. This study aims at computationally investigating the hybrid turbocharger effects on a large marine dual-fuel four-stroke engine performance and emissions characteristics as well as determining its electrical generator optimal size for the case of a ship power plant considering an actual operating profile. An existing model of a large marine four-stroke dual-fuel engine of the zero/one-dimensional type, which was developed in the commercial software GT-Power, is extended to include the hybrid turbocharger sub-model. This model is subsequently employed to carry out a parametric investigation considering a wide range for the hybrid turbocharger electric motor power. The derived results are analysed to identify the variations of the investigated dual fuel engine performance and emissions parameters in the whole engine operating envelope at both the diesel and gas modes, whilst taking into account the engine and its components operational limits. For the considered annual load profile, the results demonstrate that the optimal nominal size of the hybrid turbocharger electric motor power is 300 kW and leads to an annual energy surplus between 2% and 3% of the annually delivered engine mechanical energy. This study benefits the quantification of the hybrid turbocharger impact on large marine dual fuel four-stroke engines as well as the ship energy efficiency, thus providing useful decision support to facilitate the shipboard implementation of this technology.

A multiparameter investigation of syngas/diesel dual-fuel engine performance and emissions with various syngas compositions

Syngas, also known as producer gas or wood gas, is a gaseous biofuel produced by gasification of biomass. It is mainly composed of hydrogen and carbon monoxide with a smaller share of methane, all diluted by nitrogen and carbon dioxide. Despite having carbon in its composition, since it is made from biomass, it is considered low to zero-carbon and being so makes it one candidate for reducing carbon emissions of internal combustion engines. This work focuses on the effect of different syngas compositions on the performance and the exhaust emissions of compression ignition engine with decane pilot injection as a diesel surrogate. Results showed that thermal efficiencies over 39% are possible with a variety of syngas with less than 10% energy contribution of decane. NOx and soot emissions were generally lowered by increasing the syngas/decane ratio, whereas CO and Total HC emissions increased. Additionally, relations between engine performance/emissions and fundamental properties of varying Syngas compositions were established. Further investigation on other combustion properties, such as stretch sensitivity of the syngas/air flame, are needed in order to better predict optimum operability.

Effect of manifold and port injection of hydrogen and exhaust gas recirculation (EGR) in dairy scum biodiesel - low energy content gas-fueled CI engine operated on dual fuel mode

In this current work, exhaustive research work is conducted in three phases, in the initial phase, WFO was used for producing WFO treated biomass and in the second phase, influence of PFIP and PFIT has been examined. Further in the successive phase, effect of hydrogen HMI, HPI and EGR on the combustion and emission characteristics of CRDI diesel engine operated on dual-fuel mode using DiSOME and PG combination is evaluated. In the current study, in a CRDI engine, PFIT was employed ranging from 0 to 15°CA bTDC and changed in steps of 5 and PFIP was used from 600 to 1000 bar and varied in successive steps of 200 bar. Further flow rate of hydrogen was kept 8 L/min constant and HMIT was employed in the range from TDC to 15°aTDC and changed in stages of 5. Correspondingly, HID was varied from 30 to 90°CA with 30°CA dwell and EGR was used in the range from 0 to 15% by vol. and varied in steps of 5. Outcome of the work showed that, DiSOME-PG operation with 10°bTDC PFIT, 800 bar PFIP, 10°aTDC of HMI, 60°CAHID and 5% EGR rate showed lower BTE by 5.8% and increased smoke levels by 10.8%, HC by 8.6%, CO by 6.5% and marginally decreased NOx by 6.4% was observed in comparison to the same fuel blend with zero EGR at 80% load. Further, marginally amplifiedID and CD with loweredCP and HRR has been noticed. Study revealed thatH2addition to low calorific value gas (PG), method of pilot fuel addition and EGR is affected dual fuel engine performance, but provided drastic reductions in smoke and NOx emissions.

Multi-objective optimization of dual-fuel engine performance in PPCI mode based on preference decision

In order to obtain the best emission performance and fuel economy of the dual-fuel engine in PPCI (partial premixed compression ignition) mode while responding to different decision requirements. LSTM (long short-term memory) neural network is used to build a response model that can accurately reflect the relationship between input parameters and output performance of the dual-fuel engine. A clever combination of LSTM and NSGA-II is used to construct a multi-objective performance optimization framework for the dual-fuel engine. The control parameters including MIT (main injection timing), PIT (pre-injection timing), PIQ (pre-injection quantity), EAC (excess air coefficient), SRL (substitution rate limit), and IP (injection pressure) are integrated and optimized under each load condition according to the propulsion conditions. The introduction of decision-maker (DM) preference information is creative, which allows the optimization process to include the intention of the DM, which can guide the evolutionary direction of the population. An organized combination of reference point coordinates R, weight vector w of weighted Euclidean distance, and preference strength δ is the critical one. The interactive optimization process effectively reduces the DM’s reliance on empirical knowledge in preference parameter setting. The experimental results show that all solutions at preference low emission meet the IMO Tier-III limit for NOx, and the average NOx emission at full operating conditions is 1.22 g/(kW·h), which is 78.9% lower than the original engine, along with a 4.76% reduction in BSFC compared to the original engine. When low BSFC is preferred, the average BSFC is 8.44% lower than the original engine and 3.68% lower than when low emissions are preferred. It can be found that the lower BSFC is obtained at the expense of the environment, and the pursuit of higher fuel economy worsens emissions dramatically.

Impact of injection timing (IT) on dual fuel engine fuelled with waste cooking oil methyl ester and producer gas

In present scenario fossil fuels are getting depleted, in addition to this dependency and price is increasing. A time may come in future there might fuel crises. Hence, in order to make a better future. Renewable fuels from different and large number of sources can be typically used as fuel to generate electricity and for transportation in replacement of fossil fuels. This background view describes the of injection timing (IT) effect on engine performance, combustion and characteristics of Emission using waste cooking oil methyl ester (WCOME) and induction of producer gas with pilot injection of diesel on dual fuel mode of working. Thus, experiment shows the optimization of different injection timing (IT) (19–31° in step of 4°) to improve the dual fuel engine performance. Investigation of WCOME with producer gas operation at 27° bTDC showed reduced emission levels with increased brake thermal efficiency.

Effects of Gasoline-Diesel Ratio on Combustion and Emission Characteristics of a Dual-Fuel CI Engine: A CFD Simulation

Recently, considerable efforts are made by the engine researches all over the world, focusing primarily on achieving ultra-low emissions of NOx (nitrogen oxides) and soot without any compromise to high thermal efficiency from dual-fuel engine. In this study, combustion performance and engine-out emission of a single cylinder gasoline-diesel dual-fuel engine are numerically investigated by employing a commercial computation fluid dynamics (CFD) software, especially developed for internal combustion engines modeling. Here, gasoline-diesel relative ratio has been varied to find its impacts on performance of a dual-fuel engine. The results show that, in-cylinder pressure, in-cylinder temperature and rate of heat release (ROHR) are increased with gradual increment in diesel relative to gasoline. Injecting higher amount of diesel directly inside the combustion chamber as pilot fuel might have facilitated the auto-ignition process by reducing the ignition delay and accelerated the premixed gasoline-air flame propagation. These led to shorter main combustion duration which is quite desirable to suppress the knock in dual-fuel engines. In addition, NOx emission is found to decrease with relatively higher percentage of diesel. On the other hand, with increasing gasoline ratio relative to diesel, combustion duration is prolonged significantly and led to incomplete combustion, thereby increasing unburned hydrocarbon (UHC) and carbon monoxide (CO).

A comparative study of combustion performance and emissions of dual-fuel engines fueled with natural gas/methanol and natural gas/gasoline

A comparative study on combustion characteristics and performance of a dual-fuel engine fueled with natural gas/methanol and natural gas/gasoline was conducted experimentally. All experiments were performed at an engine speed of 1600 r·min−1 with a brake mean effective pressure of 0.387 MPa. Energy substitution ratio (ESR) was defined as the energy released by methanol or gasoline to the total energy released. Four ESRs namely 0, 19, 33, and 44 % were conducted in this study. The results demonstrated that both methanol and gasoline addition accelerated the burning rate of natural gas, leading to an increased peak cylinder pressure (Pmax) and maximum heat release rate (HRRmax). The corresponding crank angle of Pmax and HRRmax advanced and approached to top dean center after methanol or gasoline enrichment for the specific spark timing (θig) and ESR. In addition, as the ESR grew from 0 % to 44 % with a θig of 25 °CA BTDC, the brake thermal efficiency (BTE) increased from 27.3 % to 28.1 % for the natural gas/methanol mixture. In contrast, BTE reduced from 27.3 % to 25.5 % for the natural gas/gasoline mixture. The total hydrocarbon and carbon monoxide emissions of natural gas engines can be lowered by adding methanol and raised by inputting gasoline.