Dual-fuel Compression Ignition Engine Research Articles

Parametric study of combustion characteristics of diesel/methanol dual fuel engine using global sensitivity analysis and multi-objective optimization

The pursuit of clean and efficient internal combustion engine power necessitates the substitution of fossil fuels with methanol and the adoption of advanced combustion strategies. This study examines the combustion and emission characteristics of methanol/diesel dual-fuel compression ignition engines. To understand the intricate interplay between critical parameters and engine performance, the global sensitivity analysis (GSA) method is employed, utilizing Sobol sensitivity as the quantitative metric. The investigated parameters include methanol substitution rate, diesel injection parameters, and five thermodynamics parameters concerning in-cylinder conditions. A validated computational fluid dynamics (CFD) model, coupled with a chemical kinetic mechanism, is developed to predict the combustion behavior of the dual-fuel engine accurately. This predictive capability forms the basis for utilizing the tree-based process optimization (TPOT) algorithm. By implementing TPOT, a significant reduction in the mean square error (MSE) of the predicted characteristics model is achieved, averaging a decrease of 73.59%. Subsequently, a multi-objective optimization is conducted, exploring the impact of varying target weights on the optimal outcomes. Results show the initial pressure significantly impacts the engine's economy, power and emission characteristics, and NOx formation should be carefully considered in the combustion optimization of dual-fuel engines.

Modeling of co-combustion of butanol with diesel fuel in a dual-fuel compression ignition engine

Modeling of co-combustion of butanol with diesel fuel in a dual-fuel compression ignition engine

The impact of ammonia and hydrogen additives on the combustion characteristics, performance, stability and emissions of an industrial DF diesel engine

Both hydrogen and ammonia are potential fuels that can significantly replace fossil fuels in the automotive and energy sectors. In compression ignition engines, they can be effectively and efficiently co-combusted with diesel fuel. This study presents experimental comparative research on the impact of alternative fuels, namely ammonia and hydrogen, on the performance, stability, and emissions of an industrial dual-fuel compression ignition engine. The research was conducted on an engine operating under constant load (0.7 MPa) and constant speed (1500 rpm), comparing scenarios of diesel-only operation and alternative fuel energy shares of 8 %, 12 %, 24 %, and 32 %. For both ammonia/diesel and hydrogen/diesel engines, combustion characteristics, performance, and emissions were determined and analyzed. Additionally, an evaluation of the dual-fuel engine’s operational stability was conducted. For the compression ignition engine co-combusting ammonia with diesel, the most favorable solution was using a 32 % energy share of NH3. In this configuration, the engine achieved nearly the highest efficiency (38 %), the most stable operation, and the lowest emissions of harmful and toxic exhaust components (NO = 2.23 g/kWh, HC = 0.2 g/kWh, CO = 24.9 g/kWh, CO2 = 512 g/kWh, Soot = 0.51 g/kWh). For the engine co-combusting hydrogen with diesel, the optimal energy share of H2 was 24 %. In this configuration, the engine achieved the highest efficiency (39.8 %), almost the most stable operation, and the lowest emissions of HC = 0.22 g/kWh, CO = 15.8 g/kWh, CO2 = 434.7 g/kWh and Soot = 0.52 g/kWh. Unfortunately, a significant drawback of using H2 in a compression ignition engine is the substantial increase in NO emissions.

Multi-objective optimization of a dual fuel CI engine powered with syngas and pilot diesel using TLBO algorithm: A metaheuristic approach

Abstract The thermochemical conversion of biomass into producer gas presents an attractive alternative fuel option for compression ignition (CI) engines, making biomass gasification a critical driver for achieving sustainable development goals. Considering the application of producer gas (PG) in CI engine, the most potential gases include H2 and CO as main fuel compounds and it is crucial to comprehensively understand the impact of these two gas components on the engine behaviour. Nowadays, artificial intelligence-powered models are frequently applied for simulating engines that run on a single type of fuel. However, their usage is not as common when it comes to modeling dual-fuel CI engines run on synthetic producer gas or syngas. The present study explores the feasibility of optimizing operational parameters, such as engine load and syngas composition, in improving the efficiency and lowering the levels of pollutants emitted by a 3.5 kW CI engine operated under dual fuel (DF) mode using syngas as primary fuel and diesel as pilot fuel. The performance and emission characteristics of syngas (H2:CO) is examined by studying its behaviour in four different combinations. The compositions of syngas are prepared based on the volumetric percentage of the H2 and CO and is inducted into the combustion chamber using a novel venturi-type air-gas mixer. In the present study, an intelligent metaheuristics-based optimization algorithm i.e., Teaching–Learning Based Optimization (TLBO) is developed and introduced, to develop a predictive model within constrained range of engine operating conditions. Further, the algorithm is used to estimate multiple engine performance characteristics simultaneously viz., brake thermal efficiency (BTE), unburned hydrocarbons (HC), and carbon monoxide (CO). The resultant findings identify the optimal engine load of 68.87% and the ideal syngas composition of 63.9% H2 and 49.5% CO as key parameters for maximizing engine efficiency while minimizing exhaust emission. At these optimized operating condition, 19.49% BTE is observed, while HC and CO emission was found to be 384.6 ppm and 445.33 ppm respectively. This shows the effective and efficiency of the proposed algorithm.

Hydrogen Use in a Dual-Fuel Compression Ignition Engine with Alternative Biofuels

Recent progress has been made towards decarbonisation of transport, which accounts for one quarter of global carbon dioxide emissions. For the short to medium term, new European Union (EU) and national energy and climate plans agree on a strategy based on the combination of increasing shares of electric vehicles with the promotion of sustainable fuels, especially if produced from residual feedstock and routes with low or zero net carbon emission. Hydrogen stands out among these fuels for its unique properties. This work analyses the potential of using hydrogen in a dual-fuel, compression ignition (CI) engine running with three diesel-like fuels (conventional fossil diesel, advanced biodiesel (BD) and hydrotreated vegetable oil (HVO)) and different hydrogen energy substitution ratios. The results were confronted with conventional diesel operation, revealing that dual-fuel combustion with hydrogen demands higher exhaust gas recirculation (EGR) rates and more advance combustion, leading to a remarked reduction of NOx emission at the expense of a penalty in energy consumption due mainly to unburnt hydrogen and wall heat losses. Unreacted hydrogen was ameliorated at high load. At low load, the use of BD dual combustion permitted higher hydrogen substitution ratios and higher efficiencies than diesel and HVO.

Experimental study on ammonia-diesel co-combustion in a dual-fuel compression ignition engine

Ammonia, as a carbon-free renewable fuel and a potential hydrogen carrier, is gaining increasing interest in addressing greenhouse gas emissions in industrial applications and transportation. This paper presents experimental studies on the co-combustion of ammonia with diesel fuel in a single-cylinder industrial compression ignition engine operating in dual-fuel mode. The energy share of ammonia ranged from 0 to 60%. Increasing the proportion of ammonia compared to diesel fuel in the compression ignition engine leads to a change in the combustion process character, increasing the kinetic combustion phase at the expense of diffusive combustion. However, it does not result in an increase in the peak pressure rise (PPR) beyond the permissible value of 1 MPa/deg for piston engines. It increases ignition delay and shortens the combustion duration, while also increasing thermal efficiency and decreasing specific energy consumption. An increase in the NH3 share results in a decrease in combustion efficiency, a reduction in unit emissions of NO, CO2, and soot, and an increase in CO emissions. Beyond 42% ammonia share, it reduces unit THC emissions. At a 42% ammonia share, the dual-fuel engine achieves the highest indicated thermal efficiency (ITE), lowest specific energy consumption (SEC), shortest combustion duration, and lowest unit soot emissions.

Impacts of Using Exhaust Gas Recirculation and Various Amount of Dimethyl Ether Premixed Ratios on Combustion and Emissions on a Dual-Fuel Compression Ignition Engine

Impacts of Using Exhaust Gas Recirculation and Various Amount of Dimethyl Ether Premixed Ratios on Combustion and Emissions on a Dual-Fuel Compression Ignition Engine

Experimental investigation of diethyl ether (DEE) blended jack fruit peel oil (JFP) with hydrogen as a secondary fuel in dual-fuel compression ignition engines.

Jack fruit peel oil (JFPO) exhibits passive chemical characteristics; thereby, dual-fuel mode frequently involves hydrogen to address its combustion difficulties. This strategy has been gaining prominence nowadays. The present investigation investigates on the performance, emission, and combustion characteristics of a direct injected compression ignition dual-fuel engine operating on a binary fuel blend of jack fruit peel oil (JFPO) and diethyl ether with hydrogen induction. The engine was operated by inducing hydrogen gas into the intake manifold of the engine at 8 and 10 LPM with the applied load ranging from 25 to 100%. The test fuel was prepared by blending jack fruit peel oil and diethyl ether in the volumetric ratio of 90:10. JFP brake thermal efficiency was 16% lower than diesel at full load but enhanced by 9% with direct hydrogen induction at a knock limit of 10 LPM and 23% with JFP + H2 + 10% DEE at maximum load. At maximum load, JFP + 10 LPM of hydrogen gas + 10% DEE produces 916ppm of NOx, which is 44.46% less than diesel. Furthermore, adding hydrogen gas and DEE to air fuel mixture decreased emissions of carbon monoxide and unburned hydrocarbon by 0.702% and 28.30% opa, respectively.

Effects of Varying Equivalence Ratios on the Combustion Efficiency Characteristic of a Dual-Fuel Compression Ignition Engine by Changing Intake Pressures and Exhaust Gas Recirculation Rates

In general, a leaner mixture condition improves combustion efficiency in compression ignition (CI) combustion using diesel. However, in the case of leaner air–fuel mixture conditions, it disturbs flame propagation in spark ignition combustion using gasoline, i.e., low reactivity fuel, causing a decrease in combustion efficiency. Since dual-fuel combustion in a CI engine typically involves the use of high- and low-reactivity fuels together, the differing reactivity conditions in the cylinder become as important as the local equivalence ratio in the cylinder. Thus, there is a need to verify the effect of a leaner mixture condition on combustion efficiency in dual-fuel CI combustion. For this reason, this study experimentally evaluates the effects of varying equivalence ratios on the combustion efficiency of gasoline/diesel dual-fueled CI combustion in a 0.4-L single-cylinder engine under low-speed (1500 rpm) and low-load (total LHV 570 J/str) conditions. To vary the equivalence ratios, intake pressures and exhaust gas recirculation (EGR) rates were, respectively, changed under the part-load condition. The results emphasize that as the equivalence ratio becomes leaner by increasing the intake pressure, combustion efficiency worsens due to the low reactivity properties and certain flame propagation modes of gasoline combustion. On the contrary, increasing the EGR rate did not significantly influence combustion efficiency, but it effectively helped reduce nitrogen oxide (NOx) emissions. Based on these results, it is concluded that optimizing dual-fuel CI combustion to suppress NOx emissions is better achieved using EGR, rather than creating a leaner mixture condition.

Effects of diesel injection timing and methanol substitution ratio on combustion and exhaust emission characteristics of a dual fuel compression ignition engine

Effects of diesel injection timing and methanol substitution ratio on combustion and exhaust emission characteristics of a dual fuel compression ignition engine

Exploring the effect of methanol and ethanol on the overall performance and substitution window of a dual-fuel compression-ignition engine fueled with HVO

All sectors where compression-ignition engines are the predominant technology are undergoing a complex change motivated by the transition to a carbon-free economy. Nevertheless, these engines, if operated under advanced combustion strategies and fueled with low carbon-intensive fuels, are a real opportunity. This work investigates the effect of two renewable short-chain alcohols (methanol and ethanol) on the performance, emissions, combustion pattern and energy substitution window of a dual-fuel engine operated at high and low loads. Diesel-like fuels include a hydrotreated vegetable oil to evaluate the potential of its high cetane number in dual-fuel mode. The work was executed in two stages. In the first, the operating parameters (EGR rate, combustion phasing) were adjusted for attaining the best compromise between engine efficiency and NOx emissions. In the second, the maximum achievable substitutions were sought, achieving higher substitution ratios than those found by others. HVO-ethanol pair led to the highest substitution (84%), although generally methanol showed superior results in NOx and thermal efficiency. HVO and high alcohol ratios broke down the existing trade-off between large and small particles, leading to a simultaneous reduction of large (more than one order of magnitude) and small (three times lower) compared to only diesel or HVO fueling.

A Review on Compression-Ignition Engine Performance And Emissions With Hydrogen-Diesel Mixtures: Effect Of Operational Parameters

The combustion of conventional fuel in Compression-Ignition (CI) engines is generally understood as a primary cause of hydrocarbon exhaust emissions. Alternative fuels and hydrocarbon fuels can be mixed to lower pollution emissions while enhancing engine efficiency. Here, the various variables which impact emissions and engine efficiency are fully illustrated. Numerical work on the engine was done to examine the working and outflow patterns of a dual-fuel CI engine at various fuel combination ratios. In the test setup, diesel is used as main fuel and hydrogen and air as the controlling fuel. In order to formulate this special CI engine numerically, three-dimensional computer based analytical tools were used. For this method, n-heptane was chosen as reaction fuel and a reduced-reaction mechanism was taken into account. To investigate the soot formation rate inside the cylinder, the model by Hiroyasu-Nagel was developed. Here, a study looks into the performance effects on the variations of secondary fuel and its emissions. Presence of good amount of hydrogen during combustion results in better thermal efficiency and better performance. As the hydrogen rate increased, ignition timing was delayed as a result of a time lag in the OH component’s evolution. Meanwhile, Exhaust Gas Recirculation (EGR) and timing of the diesel incorporation strategies are also taken as important performance parameter.

Effect of cross-flow velocity on spray evolution and impingement characteristics of a multi-hole port fuel injector

The location and orientation of the injector play a crucial role in determining engine performance and emissions from spark ignition and dual-fuel compression ignition engines. This study focuses on the spray atomization and downstream mixing of gasoline injected from a multi-hole port fuel injector in a crossflow. This study employed the phase Doppler interferometry technique to extract the droplet size and velocity distributions for the flow confined in a circular duct with a diameter similar to the intake port of the dual-fuel compression ignition engine. The flow velocity was maintained at 10 m/s at 1 atm pressure and 299 K temperature. The spray characteristics were compared for the quiescent and crossflow cases. The spray evolution was analyzed using a high-speed imaging technique. Near wall impingement analysis has been carried out using the spray impingement models. The early stage spray evolution was similar for the quiescent and crossflow cases. The horizontal velocity of the spray was found to be ∼12 m/s at 20 mm downstream of the injector. The velocity remained similar for the flow and no-flow cases, as drag force was found to have an insignificant effect. The drag force was estimated to be one order of magnitude higher for the 15-μm droplet than the 50-μm droplet. The maximum Sauter mean diameter observed for the flow case inside the spray was 53 μm, which was 18% higher than the maximum Sauter mean diameter of the no-flow case. The droplet Sauter mean diameter increased along the spray due to the coalescence of slow-moving droplets. The droplet breakup was found to be insignificant downstream of the spray. The flow entrained the droplets smaller than 30 μm. The spray-wall impingement criterion estimated around 42% of droplets to bounce off the surface at 50 mm, compared to 22% without flow.

Effect of addition of diethyl ether with custard apple seed oil + hydrogen enrichment on dual-fuel compression ignition engine

Due to the inert chemical properties of custard apple seed oil (CASO), one standard method for overcoming the challenges with its combustion is to use hydrogen as a supplemental fuel in dual-fuel mode. This is a technique that has developed in prominence in recent years. This investigation aims to examine the combustion characteristics of a DI engine that has been fuelled with CASO-blended di-ethyl ether (DEE), as well as hydrogen used as a secondary fuel. The experiment was conducted in atmospheric air with hydrogen enrichment (8 and 10 LPM) using CASO and CASO + 20% DEE as fuel for load condition varying from (25–100%). When compared to diesel at full load, the brake thermal efficiency of CASO was lower by 16%; however, it was improved by 9% with direct hydrogen induction at a knock limit of 10 LPM; and it was improved by 23% with CASO + H2 + 20% DEE when operating at maximum load. NOx emissions for CASO + 10 LPM H2 + 20% DEE at maximum load is 926 ppm, which is around 45.46% less than the emission value for diesel. When more hydrogen was added to the combination, the presence of DEE in the fuel caused a reduction in the emissions of both hydrocarbon and carbon monoxide around 21.70% opacity and 0.711%vol, respectively, which leading to a cleaner environment.

The combined effect of hydrogen enrichment and exhaust gas recirculation on the combustion stability, performance and emissions of CI engine energized by algae biodiesel

The scarcity of fossil fuels, the rising cost of liquid fuels, and the wide pollution footprint of conventional fuels all motivate scientists to seek out new approaches. This experimental study aims to explore the performance and emissions of compression ignition (CI) engines by introducing hydrogen into a biodiesel blend derived from algae. According to this study, the superior thermal properties of hydrogen associated with algal biodiesel have a significant impact on the performance and emissions of dual-fuel engines. The effect of hydrogen substitution rates of 10.4, 21.6, 32.4, 43.2, and 54 g per hour (g/h) on pure algae biodiesel was investigated. In comparison to diesel, the algae biodiesel reduces unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions by 4.1% and 8.82%, respectively, while nitrogen oxide (NOx) emissions increase by 18%. Diesel was found to have increased brake thermal efficiency (BTE) and decreased brake specific energy consumption (BSEC) compared to biodiesel. With the addition of pure biodiesel, the 43.2 g/h H2 substitution rate produces a maximum thermal efficiency of 1.92% and a 9.5% decrease in brake-specific energy consumption compared to diesel at maximum load. Compared to diesel, the emission attributes of UHC, CO, and smoke opacity decreased by about 45%, 48%, and 41%, respectively. However, NOx emissions increase by about 36% compared to diesel due to the higher flame temperature and carbon-free fuel of hydrogen and oxygenated biodiesel. The induction of 15% exhaust gas with B100 + 43.2 g/h H2 reduces NOx by about 31% in comparison to B100 + 43.2 g/h H2 without exhaust gas recirculation (EGR). This is primarily attributable to the high oxygen dilution and specific heat capacity of burned gases, which result in a decrease in peak cycle temperature. Compared to diesel, B100 + 43.2 g/h H2 increased the cylinder pressure and heat release rate by about 1.86 and 4.29%, respectively. As a result of its high energy density, hydrogen improves overall energy utilization and engine performance. Hydrogen's rapid flame speed and wide flammability range contribute to the efficient and complete combustion of the algae fueling the CI engine. As well as showing outstanding performance, dual fuel CI engines have the potential to significantly contribute to lowering emissions. Finally, it was determined that using algae biodiesel and exhaust gas recirculation with hydrogen substitution in diesel engines can significantly reduce emissions while increasing efficiency.

Impact of Hydrogen on Emission Reduction in a CI Engine when Fuelled with Blends of Diesel-Waste Cooking Biodiesel

Waste utilisation and emission of greenhouse gases are two of the world's most pressing challenges today. This study seeks to solve the problem generated by the disposal of Waste Cooking Oil (WCO) as a tiny step forward in contributing to the reduction of waste disposal. WCO has a high potential as a bio fuel for internal combustion engines, hence it was chosen for this investigation. WCO of 20% and diesel 80% is used. This study looks at the performance, combustion and emission parameters of a dual fuel compression ignition engine running on WCO biodiesel with a hydrogen additive at atmospheric condition. The parametric study include variation in engine load (0-18 kg) and hydrogen flow rate (3, 6, 9 LPM). The experiment was conducted on a four-stroke diesel (computerized), single cylinder, water cooled power at 5.2 kW at 1500rpm Kirloskar engine. From the experiment overall parametric variation of 35.38%, 34.06% and 32.37% of brake thermal efficiency was obtained and emission was observed. However, with increase of hydrogen flow rate resulted in increased engine performance, increase in CO, NOx and reduction in emission of UBHC and CO2.

Experimental and simulation study of methanol/coal-to-liquid (CTL) reactivity and combustion characteristics of diesel engines in RCCI mode

An experimental and simulation study of the RCCI combustion mode of coal-based fuels (methanol prepared from coke oven gas/coal-to-liquid, Methanol/CTL)) was carried out on a modified dual-fuel compression ignition (CI) engine. The mechanism by which Methanol/CTL, which has a significant difference in reactivity, promotes engine combustion and thermal efficiency is revealed. The results show that with the increasing load (i.e., load recovery ratio (LRR)) supplied by methanol, the reactivity gradient inside the cylinder increased from 28% to 451%, and the area of the ignition region was rapidly enlarged, and the reactivity of the ignition region increased. The HC and CO emissions increase by 1350% and 6866%, while the soot and NOX are reduced by a maximum of 25% and 15%. The reactivity of the ignition region increased by 8% to 26 %. Diffusion combustion forms a strong linear correlation with reactivity, with a maximum reduction of about 30 times in the premixed-to-diffusion combustion ratio. Concentration of the exothermic centre towards the top-dead-centre (TDC) is increased by a maximum of 18%, with an increase in the coefficient of variability (COV) by a maximum of 90%, indicative thermal efficiency (ITE) by a maximum of 22% and brake thermal efficiency (BTE) by a maximum of 17%. The LRR does not exceed 50% while the engine maintains stable operation and 30% while maintaining power and fuel economy.

Investigation of the effects of hydrogen energy ratio and valve lift amount on performance and emissions in a hydrogen-diesel dual-fuel compression ignition engine

The inadequacy of internal combustion engines using diesel fuel to meet emission standards has made it necessary to make radical innovations in these engines. With the use of hydrogen-diesel dual fuel mode, it is possible to increase the performance of these engines and reduce their emissions. However, there are many obstacles to the use of dual fuels. The most important of these obstacles is the decrease in the volumetric efficiency with the increase of the hydrogen energy ratio. To solve this problem, more air must be taken into the cylinder at the suction stroke. In this study, the effects of hydrogen energy ratio and intake valve lift amount on performance and emissions in hydrogen-diesel dual fuel mode were experimentally investigated. Experiments; constant speed (1850 rpm), different load (3, 4.5, 6, 7.5, 9 Nm), different hydrogen energy ratios (7, 9, 11, 13, 15) and made in different intake valve lift (4.0, 4.46, 4.9 mm) amounts. Compared to pure diesel and standard valve lift at 9 Nm load, 40% reduction in soot emissions and 33% reduction in CO emissions was determined when the hydrogen energy ratio was adjusted to 7% and the valve lift amount was increased by 10%.

Efficacy of machine learning algorithms in estimating emissions in a dual fuel compression ignition engine operating on hydrogen and diesel

Emission created by combustion of fossil fuels are a major concern of the world for the past few decades. The stringent emission norms have impacted the automobile manufacturers to work on exhaust emissions and its impact. This research focused on using machine learning regression models to evaluate the efficacy of experimental results for a dual fuel compression ignition (CI) engine operating on hydrogen and diesel. In the present study, engine emissions were estimated using 29 regression algorithms. A total of 5 input data namely, concentration of hydrogen, engine load, diesel intake, speed and equivalence ratio were considered in the study to estimate various emissions like oxides of nitrogen (NOx), carbon dioxide (CO2), hydrocarbon (HC) and smoke. Correlation coefficient, mean absolute error, root mean squared error, relative absolute error and root relative squared error were adopted as the performance metrics in the present study. Amongst the algorithms considered, pace regression, radial basis function regressor, multilayer perceptron regressor and alternating model tree produced the highest correlation coefficient of 0.9985, 0.8958, 0.9950 and 0.9256 in estimating the engine emissions like CO2, smoke, NOx and HC respectively. Additionally, an attempt was made to establish an individual algorithm that can estimate all the emissions was identified as multilayer perceptron regressor with correlation coefficient values of 0.9977 (CO2), 0.9950 (NOx), 0.8501(smoke) and 0.8731(HC) respectively.

Co-Combustion of Hydrogen with Diesel and Biodiesel (RME) in a Dual-Fuel Compression-Ignition Engine

The utilization of hydrogen for reciprocating internal combustion engines remains a subject that necessitates thorough research and careful analysis. This paper presents a study on the co-combustion of hydrogen with diesel fuel and biodiesel (RME) in a compression-ignition piston engine operating at maximum load, with a hydrogen content of up to 34%. The research employed engine indication and exhaust emissions measurement to assess the engine’s performance. Engine indication allowed for the determination of key combustion stages, including ignition delay, combustion time, and the angle of 50% heat release. Furthermore, important operational parameters such as indicated pressure, thermal efficiency, and specific energy consumption were determined. The evaluation of dual-fuel engine stability was conducted by analyzing variations in the coefficient of variation in indicated mean effective pressure. The increase in the proportion of hydrogen co-combusted with diesel fuel and biodiesel had a negligible impact on ignition delay and led to a reduction in combustion time. This effect was more pronounced when using biodiesel (RME). In terms of energy efficiency, a 12% hydrogen content resulted in the highest efficiency for the dual-fuel engine. However, greater efficiency gains were observed when the engine was powered by RME. It should be noted that the hydrogen-powered engine using RME exhibited slightly less stable operation, as measured by the COVIMEP value. Regarding emissions, hydrogen as a fuel in compression ignition engines demonstrated favorable outcomes for CO, CO2, and soot emissions, while NO and HC emissions increased.