SI Engine Research Articles

Modeling and simulation of SI engine muffler for prediction of backpressure by optimizing porosity and muffler diameter

Air Pollution produced from automobiles has become one of the most critical problems of environmental concern and likely to increase as vehicle population is assumed to grow approximately by 1300 million by the year 2030. In India, automobiles will have to meet the BS-VI emission standards to reduce vehicular pollution that impacts on environment and human health. These norms impose various restrictions on emissions of exhaust gases like NOx, HCs, particulate matter. Many recent exhaust control devices are being developed to meet the required needs. Therefore, the present study aims to reduce CO2 emissions generated in SI engine automobiles using activated carbon/calcite in a muffler. The backpressure parameter of the muffler affects the efficiency of an internal combustion engine. The porosity and diameter of the inner tube of the muffler has a prominent effect on backpressure. Therefore, the muffler with 48, and 60 holes, respectively and 1mm and 2mm diameter, respectively on a perforated tube have been investigated. The result shows that the concentration of CO2 and back pressure is greatly reduced by increasing porosity and diameter, respectively of the tube. Thus, an environmentally friendly and efficient muffler is modeled and simulated.

Experimental investigation of the effect of liquid petroleum gas on frictional power loss for performance enhancement of SI engine

Alternative gaseous fuels being clean, economical, and available in large quantity encourage the focus on optimizing various operating conditions for internal combustion engines. Alternative fuel as LPG is being considered to restore the role of alternative fuel to improve fuel economy by reducing fuel consumption and total frictional power loss compared to petrol fuel. The engine is tested using LPG and petrol so that comparison of the engine performance concerning fuel consumption and frictional power loss using Morse test. The conventional 4 Cylinder, 4 Stroke Spark Ignition engine expending a hydraulic dynamometer is used for experimentation. To find the most influencing factors from various input parameters of an engine like engine speed, load on the engine, engine oil viscosity which strongly affects engine frictional power loss. The comparative analysis of petrol and LPG fuels with different multi-grade engine oils shows that the mechanical efficiency obtained from the Morse test are 68.37%, 65.75% and 64.69% at 1750 rpm for petrol fuel with SAE20W30, SAE05W40 and SAE20W50 respectively, while for the same operating condition these values with LPG fuels are 62.99%, 61.85% and 59.85% respectively for SAE20W30, SAE05W40 and SAE20W50 engine oils at1750 rpm. Buckingham Pi-theorem is used to calculate, an experimental data-based mathematical model for which various pi-terms are determined, applying dimensional analysis for selected parameters for predicting outcomes as frictional power loss and fuel consumption rate.

The Influence of LPG and DME Mixtures on Passenger Car Performance

The paper presented the dynamics of a vehicle fueled by hybrid fuel, i.e., LPG–DME mixture. The basis for the assessment was the T-ω characteristics of the SI engine with a capacity of 1.6 dm3, determined by the authors for several selected loads and DME mass shares in the engine supply mixture. The analysis and comparison of the impact of the composition of the LPG–DME mixture on the dynamic properties were carried out for the passenger car OPEL Astra, powered by an engine for which T- ω characteristics were determined earlier on the test bench. It has been shown that the mass share of DME in the LPG–DME mixture does not significantly reduce the dynamic index of the car. In addition, the scope of changes in the mass fraction of DME in the mixture was also determined, which will ensure the vehicle performance similar to the power and torque parameters obtained for an engine powered solely by LPG. The received results have made it possible to determine changes in the value of the maximum dynamic coefficient, maximum acceleration, and car acceleration time for selected engine loads and various DME shares in the mixture. The thesis that DME can be considered as an activator of the combustion process and may have an impact on the vehicle dynamics is confirmed.

Detecting the Flame Front Evolution in Spark-Ignition Engine under Lean Condition Using the Mask R-CNN Approach

In the wake of previous works, the authors propose a new approach for the identification and evolution of the flame front in an optical SI engine. Currently, it is an essential prerogative to characterize the capability of innovative igniters to guarantee earlier flame development in critical operating conditions, such as ultra-lean mixture, towards which automotive research is moving to deal with the ever more stringent regulations on pollutant emissions. The core of the new approach lies in the R-CNN Mask method. The latter consists of a conceptually simple and general framework for object instance segmentation. It can efficiently detect objects contained in an image while simultaneously generating a high-quality segmentation mask for each instance. In particular, the aim this work is to develop an automatized algorithm for detecting, as objectively as possible, the flame front evolution of lean/ultra-lean mixtures ignited by low-temperature plasma-based ignition systems. The capability of the Mask R-CNN algorithm to automatically estimate the binarized area, without setting a defined binarized threshold, allows us to perform an analysis of the flame front evolution completely independent from the user interpretation. Mask R-CNN can detect the kernel in advance and can identify events as regular combustions instead of misfires or anomalies if compared to other traditional approaches. These features make the proposed method the most suitable option to analysis the real behavior of the innovative ignition systems at critical operating conditions.

Study on Combustion and Emissions of a Spark Ignition Engine with Gasoline Port Injection Plus Acetone–Butanol–Ethanol (ABE) Direct Injection under Different Speeds and Loads

ABE can be used as an alternative fuel for engines. This paper studies the combustion and emission performances of an SI engine with GPI plus ABEDI at different engine speeds and loads. The engine operating conditions included speeds of 1000–2600 rpm at the MAP = 50 kPa and loads of MAP = 30–70 kPa at a speed of 1800 rpm. The ABEDIr contained 0%, 20%, 40%, 60%, 80%, and 100%. At speeds = 1000–1800 or 2200–2600 rpm, the testing results showed the ABEDIr corresponding to the maximum IMEP at 80% or 100%. When the ABEDIr = 60%, HC and NOx emissions were the lowest at speeds of 1000–2600 rpm. Meanwhile, NPN and APN both decreased with the increasing of ABEDIr. As the MAP increased, CA0-90 decreased. At different loads, ABE-added fuels had lower HC and NOx emissions and higher IMEP values than pure gasoline. PN was lower than 4 × 104 n/cm3 when the ABEDIr was over 80%. Overall, 80% ABEDIr is a great choice for engine performance at the test range of loads and speeds, and pure ABE fuel is better if the power performance is the main requirement at high speeds and loads.

Enhancement of the performance and emissions reduction of a hydroxygen-blended gasoline engine using different catalysts

Recently, Egypt has been suffering from rapid and considerable growth in fossil fuel demand, especially in the transportation sector. Hydroxy (HHO) gas which is generated from water electrolysis process has a significant effect on increasing the engine performance, and reducing fuel consumption, and emissions. In the present work, a dry fuel cell is constructed and tested under different types of electrolysis, different concentrations of electrolytes, and different numbers of neutral plates (NP) to obtain the most economic, safe, and best cell quality suitable for different engine operating conditions. A 183-cc single cylinder SI engine connected with a hydraulic pump, in one unit, was used for the study. HHO gas was supplied to the intake manifold of the engine under different conditions. The results showed that engine performance is most improved by using HHO gas generated by KOH electrolyte, 4 NP, at 1500 rpm. Under the optimum conditions, the maximum increase in the engine/pump efficiency was 47.24 %, maximum decrease in specific fuel consumption (SFC) was 32.1 %, and maximum reduction in CO and HC emissions were 91.7 %, and 34.84 %, respectively.

Multi-objective Optimization and Sensitivity Analysis of the Parameters Affecting Sealing Performance of the Piston Rings Face through the Validated Model for the Four-stroke Bi-fuel Engine

A multi-objective optimization study and sensitivity analysis of a SI engine piston-rings pack using dynamics analysis software (AVLExcite Piston&Rings) and optimizer software (modeFRONTIER) are presented. The effects of changing the piston rings' tangential force and face profile on the oil and gas flow behavior inside the piston-rings pack are investigated by calculating the lubrication oil consumption, blow-by, and power losses. The feasibility of the simulation model was determined by comparing it to empirical data obtained from experimental testing of the engine to estimate the amount of oil consumption and blow-by gas flow. Using the statistical modeling algorithm SS-ANOVA, multi-objective optimization investigates the individual and interaction effects of the three rings' tangential forces. This method significantly reduces the time and cost required to find the optimal design, an approach not reported in previous studies. The results showed a strong correlation between simulation and experimental test results, indicating an acceptable match during model validation. Furthermore, the predictions show that tangential forces affect sealing performance; thus, modifying the tangential force resulted in a 30% reduction in oil consumption and less than a 0.8 percent increase in friction. Furthermore, the LKZ oil control ring model efficiently reduces oil consumption by 25% while slightly increasing friction (about 10 percent without face coating).

Experimental and Numerical Study on the Effect of Nitric Oxide on Autoignition and Knock in a Direct-Injection Spark-Ignition Engine

<div class="section abstract"><div class="htmlview paragraph">Nitric Oxide (NO) can significantly influence the autoignition reactivity and this can affect knock limits in conventional stoichiometric SI engines. Previous studies also revealed that the role of NO changes with fuel type. Fuels with high RON (Research Octane Number) and high Octane Sensitivity (S = RON - MON (Motor Octane Number)) exhibited monotonically retarding knock-limited combustion phasing (KL-CA50) with increasing NO. In contrast, for a high-RON, low-S fuel, the addition of NO initially resulted in a strongly retarded KL-CA50 but beyond the certain amount of NO, KL-CA50 advanced again. The current study focuses on same high-RON, low-S Alkylate fuel to better understand the mechanisms responsible for the reversal in the effect of NO on KL-CA50 beyond a certain amount of NO. Experiments were conducted to measure the responses of KL-CA50 and trace-autoignition CA50, the latter being indicative of CA50 at which end-gas autoignition starts to become measurable from the apparent heat-release rate. Chemical-kinetics simulations were conducted to reveal the role of NO for end-gas autoignition, with a specific focus on sequential autoignition in a thermally stratified end-gas.</div><div class="htmlview paragraph">The simulation results reveal that the magnitude of low-temperature heat release (LTHR) generally increases with NO. However, the relative importance of NO for enhancing LTHR diminishes when the LTHR inherent to a fuel’s chemistry is strong, such as at lower temperatures in a thermal boundary layer. This rendered more uniform LTHR within a hypothetical thermal boundary and led to a more sequential (<i>i.e.</i> slower) autoignition event. It was also revealed that a change in compression ratio influences the importance of intermediate-temperature heat release (ITHR) due to changes of the temperature-pressure history of the end-gas. Together with the condition where end-gas autoignition occurs more sequentially, the shorter time spent in LTHR and ITHR regime can counter the increase in autoignition reactivity at high NO levels and allow KL-CA50 to advance.</div></div>

Hybrid Propulsion in SI Engines for New Generation Motorcycles: A Numerical-Experimental Approach to Assess Power Requirements and Emission Performance

Worldwide mopeds and motorcycles are taking on a growing main role in private mobility with a direct impact on air pollution, particularly in urban contexts of many Asian and European countries. In a preceding experimental investigation, HC and CO emissions were measured in the exhaust of a last-generation motorcycle belonging to the Euro-3 legislative category. Since exhaust emissions and fuel consumption are very sensitive to variations in vehicles instantaneous speed and acceleration, in this research new experimental results are used to recognize the kinematic parameters that cause higher engine-out emissions. In this paper, the hybrid electric propulsion is proposed for motorcycle application to reduce exhaust emissions in particular driving conditions which include high levels of acceleration with resultant rapid steep increase in engine speed. In such operating conditions, an enrichment of the air/fuel mixture is required, which affects the catalyst conversion efficiency. Subsequently, the power requirements and the grade of electrical assistance in such driving situations are calculated by a procedure based on both the measured exhaust emissions and the kinematic parameters of the driving dynamics collected during the experimental tests. Lastly, the share of CO and HC emissions that could be saved utilizing a hybrid motorcycle instead of a conventional thermal motorcycle is estimated through a specific environmental analysis.

Optimization of SI Engine Performance Operating with Low Octane Gasoline and Fuel Additives from Waste

Fuel additives from waste have been suggested to enhance low octane commercial gasoline in this study. Four samples were prepared in addition to pure commercial gasoline and denoted as GF0, GF4, GF8, GF12, and GF 16 which refer to fusel oil addition ratio of 0%, 4%, 8%, 12, and 16% respectively. Engine speed was controlled and increased manually from 1000 rpm to 3000 rpm at an increment of 500 rpm. Design of experiments is used to indicate the optimum additive dosage through response surface method optimization. Obtained results show that increasing engine speed significantly impacts the engine brake power, brake-specific fuel consumption, and brake thermal efficiency with a slight change for fusel oil ratio. Accordingly, it can be concluded that the maximum increase in output variables is statistically linked with the engine speed. The output response values at optimized conditions were 2.61812 kW brake power, 0.2431 kg/kW.hr brake-specific fuel consumption, and 36.5303% brake thermal efficiency. Based on the P-value, ANOVA data indicate that engine speed was a significant factor influencing output responses, while the fusel oil ratio was insignificant. However, fusel oil ratio of 8% has a significant effect on the brake thermal efficiency and BSFC.

Effect of natural gas direct injection (NGDI) on the performance and knock behavior of an SI engine

The unique properties of natural gas (NG), including high availability and lower cost compared with other fossil fuels, make it attractive in internal combustion engine (ICE) application. NG is composed mainly of methane and has greater knock resistance than gasoline, enabling higher compression ratios (CR). In contrast with the distinctive advantages, the NG fueled engines suffer from lower power and torque outputs. To address the subject, this study proposes an approach employing NG direct injection (NGDI) strategy (with higher volumetric efficiency unlike port injection), enabling a higher CR irrespective of knock limit. This work applies reactive computational fluid dynamics (CFD) to investigate spark ignited co-combustion of direct-injected NG with port-admitted gasoline. The results are validated against experimental data. In all simulated cases, the equivalence ratio (i.e., ∅ = 1) and the total input energy are kept constant. Engine performance is evaluated for three CRs (10.5, 11.5, and 12.5:1), five proportion of CNG (RCNG) and at part- and full-load conditions at an engine speed of 1500 rpm. Results indicated that while running RCNG = 100 % with a CR of 10.5:1, carbon monoxide (CO) and carbon dioxide (CO2) emissions were decreased by 29.3 % and 23.5 % respectively, compared to RCNG = 0 %. The corresponding emission reduction at CR = 11.5:1 was 27.1 % and 24 %; at CR = 12.5:1 they were 29.6 % and 23.5 % respectively. At each CR, the knock intensity at full load fell significantly as the percentage of NG increased. At a CR of 12.5:1, ringing intensity (RI) at full load decreased by 88.6 % when using RCNG = 100 %, instead of RCNG = 0 %. Under the same conditions, RCNG = 25 % cut RI by 56 %.

Highly time-resolved heat flux measurement in a combustion engine

In this study a fast-response Atomic Layer Thermopile (ALTP) based heat flux measurement system is used for wall heat-flux determination in the combustion chamber of a commercially available SI-gasoline combustion engine. The ALTP system provides further process variables that supplement conventional cylinder pressure data with data that are highly resolved in time and location. The newly developed sensor modules were precisely calibrated and compared with other measurement techniques with radiation- and convection-based procedures. Quantitative highly time-resolved measurements with frequency resolutions up to 1 MHz are performed in the engine from low to full load and up to full speeds. Single-cycle and cycle-to-cycle measurements display the quality and high temporal resolution of the measurement system. The comparison of pressure and the heat-flux measurements shows the benefits of ALTPs for detection of engine, combustion and flow characteristics. The time progression of the heat flux curves and their autocorrelated signals show only minor noise interference. The measured results display significantly higher local peak heat flux densities with values up to 1250 Wcm−2 for certain measurement points and engine conditions than reported previously in literature for SI engines. A regression analysis suggests that the high peak heat flux densities obtained are caused by the significant higher engine power-levels per cylinder. The measured data compare well with regressions extrapolated from reported literature data. A provided uncertainty analysis revealed significant influencing parameters. The variation of thermal wall parameters with 20%–30% uncertainty are playing an essential role in particular.

Investigation of the effects of water injection into an SI engine running on M15 methanol fuel on engine performance and exhaust emissions

The use of alternative fuels is an effective method to reduce pollutant emissions from spark-ignition engines. However, the usage of alternative fuels alone will not be adequate comply with strict emission standards. Water injection is one of the measures taken during combustion to achieve the desired emission values. However, deterioration in engine performance, which is not desired, occurs with the measures taken. In this study, a gasoline-methanol blend (85% gasoline + 15% methanol) was used as a fuel in a spark-ignition engine. Water was injected into the intake manifold at different rates to reduce emissions further and improve engine performance in an engine running on M15 fuel. Water was injected into the intake air with an electronic control system with 10, 20, and 30% mass ratios of the engine fuel consumption. As a result of the experimental studies conducted under full load conditions, it was determined that the effective power decreased by 2.5%, and the specific fuel consumption increased by 3.5% compared to the standard condition in the engine fueled with M15. It was revealed that there was a 6% decrease in HC emission at 2200 rpm and a 4% decrease in NOx emissions at 2600 rpm. In comparison to standard engine data, when water injection was applied to the engine, there was a decrease up to 16% in HC emissions and up to 12% in NOx emissions. In comparison to the standard data, an increase of 2.5% in the effective power was observed with 20% water injection in the effective power.

Effects of Compression Ratios on Combustion and Emission Characteristics of SI Engine Fueled with Hydrogen-Enriched Biogas Mixture

The effects of hydrogen-enriched biogas on combustion and emissions of a dual-fuel spark-ignition engine with different hydrogen concentration ratios were studied numerically. A 1-cylinder spark ignition was used to perform a numerical simulation. To reveal the influence of the compression ratios on combustion and emissions of a gaseous engine, the crankshaft of the engine was modified to generate different compression ratios of 8.5, 9.0, 9.4, 10.0, and 10.4. The biogas contained 60 and 40% methane (CH4) and carbon dioxide (CO2), respectively, while the hydrogen fractions used to enrich biogas were 10, 20, and 30% of the mixture by volume. The ignition timing is fixed at 350 CA°. The results indicate that the in-cylinder pressure, combustion temperature, and combustion burning speed increase gradually with increasing hydrogen concentration due to the combustion characteristics of hydrogen in blends. As increasing the compression ratio, NOx emissions increase proportionally, while CO2 emissions decrease gradually. Almost no combustion process occurs as operating the compression ratio below 8.5 when using pure biogas. However, adding 20% of hydrogen fraction could improve the combustion process significantly even at a low compression ratio.

Effects of second hydrogen direct injection proportion and injection timing on combustion and emission characteristics of hydrogen/n-butanol combined injection engine

Hydrogen and n-butanol are superior alternative fuels for SI engines, which show high potential in improving the combustion and emission characteristics of internal combustion engines. However, both still have disadvantages when applied individually. N-butanol fuel has poor evaporative atomization properties and high latent heat of vaporization. Burning n-butanol fuel alone can lead to incomplete combustion and lower temperature in the cylinder. Hydrogen is not easily stored and transported, and the engine is prone to backfire or detonation only using hydrogen. Therefore, this paper investigates the effects of hydrogen direct injection strategies on the combustion and emission characteristics of n-butanol/hydrogen dual-fuel engines based on n-butanol port injection/split hydrogen direct injection mode and the synergistic optimization of their characteristics. The energy of hydrogen is 20% of the total energy of the fuel in the cylinder. The experimental results show that a balance between dynamics and emission characteristics can be found using split hydrogen direct injection. Compared with the second hydrogen injection proportion (IP2) = 0, the split hydrogen direct injection can promote the formation of a stable flame kernel, shorten the flame development period and rapid combustion period, and reduce the cyclic variation. When the IP2 is 25%, 50% and 75%, the engine torque increases by 0.14%, 1.50% and 3.00% and the maximum in-cylinder pressure increases by 1.9%, 2.3% and 0.6% respectively. Compared with IP2 = 100%, HC emissions are reduced by 7.8%, 15.4% and 24.7% and NOx emissions are reduced by 16.4%, 13.8% and 7.9% respectively, when the IP2 is 25%, 50% and 75%. As second hydrogen injection timing (IT2) is advanced, CA0-10 and CA10-90 show a decreasing and then increasing trend. The maximum in-cylinder pressure rises and falls, and the engine torque gradually decreases. The CO emissions show a trend of decreasing and remaining constant. However, the trends of HC emissions and NOx emissions with IT2 are not consistent at different IP2. Considering the engine's dynamics and emission characteristics, the first hydrogen injection proportion (IP1) = 25% plus first hydrogen injection timing (IT1) = 240°CA BTDC combined with IP2 = 75% plus IT2 = 105°CA BTDC is the superior split hydrogen direct injection strategy.

Ternary gasoline – Pomegranate peel oil (PPO)- tertiary butyl alcohol (TBA) blend as an enabler to improve the spark-ignited engine performance and emissions

This paper reported a research work that investigated the compatibility of using pomegranate peel oil (PPO) as a substitute for gasoline in a spark-ignition engine. Initially, fuel characterization was performed for the PPO biofuel, and a blend was prepared by blending PPO in gasoline at a ratio of 10:90 by volume. Then, fuel properties were measured for the gasoline, PPO, and its blend. Subsequently, engine experiments were conducted for the blend at different load conditions with constant speed, and the performance, combustion, and emission results of the blend were compared with that of sole gasoline. By analyzing the results, it was found that the brake thermal efficiency of the 10% PPO blended gasoline was reduced by 1.2%, 0.6%, and 1%, at low load, mid load, and full load, respectively, when compared to sole gasoline. Whereas the HC and CO emission of the blend was higher by about 11.7% and 8.3%, respectively, at full load, when compared to that of gasoline. With an intent to improve the performance of the PPO blend, tertiary butyl alcohol (TBA) was blended with the 10% PPO blended gasoline in the volumetric proportion of 5%, 10%, and 15% to form ternary blends. The experimental study revealed that the performance of the PPO blend was enhanced significantly with increasing TBA proportion in the blend. The PPO blend with 15% TBA exhibited the highest BTE of 25.1%, which was 1.6% higher than gasoline at full load. The same blend resulted in the HC and CO emissions that were 9.2% and 9.6% lesser than gasoline, respectively, whereas NO emission was 7.6% higher than gasoline, at full load condition. The combustion analysis revealed that the start of combustion was delayed, with peak pressure and heat release rate being the maximum for ternary blends. From this investigation, it can be concluded that the sole gasoline can be replaced by the ternary blend as fuel for SI engine operation without requiring any major engine modification.

Numerical investigation on combustion system optimization for direct injection of aviation kerosene in a two-stroke SI engine for unmanned aerial vehicle

In recent years, the transition from gasoline to heavy fuel has received more and more attention in the application of unmanned aerial vehicles (UAVs). This study aims to convert a two-stroke port fuel injection (PFI) gasoline engine as the prototype engine to a direct injection (DI) aviation kerosene engine by numerical simulations. The direct-injection combustion system was designed, and then the effects of fuel injection timing and ignition strategy on combustion and knock of a two-stroke direct injection spark-ignition (DISI) engine with aviation kerosene as fuel were evaluated. The results show that the direct-injection combustion system can increase the airflow velocity, thereby accelerating fuel diffusion and flame propagation. The knock intensity (KI) and indicated mean effective pressure (IMEP) all decrease with the retardation of the injection timing and spark timing. Injection timing has a greater impact on IMEP than spark timing. For different injection timings, spark timing has a more obvious impact on KI when injection timing is advanced. The coordinated control strategy of advancing injection timing and retarding spark timing can effectively suppress the tendency of knock and broaden its load range, which can make the power recovery rate reach 88.57% compared to the baseline engine.

Analysis on Emissions of Gasoline Engine with Different Ethanol Blends at Different Compression Ratio

Alcohol fuels do have some extra benefit compare to other alternative fuels, like the capability to work in existing engines also have the ability to decrease harmful emissions. Among the various alcohols, ethanol is considered most appropriate fuels for SI engines, because of its superior fuel quality and ecological benefits. In this experiment, ethanol was blended in different ratios as 0%, 5%, 10% and 20% with gasoline. The effect of the ethanol/gasoline blends on engine emissions at various compression ratios (CRs) of 10:1, 10.5:1, 11:1 and 11.5:1 was studied and examine by using computerized single cylinder, 4 stroke, multi-fuel, variable CRs engine. Engine emission characteristics are studied experimentally by the combustion of different blends of E0, E5, E10 and E20 at different loads of 0 kg, 1 kg, 2 kg and 3 kg. Result shows that adding ethanol in gasoline engine at CRs of 10:1, 10.5:1, 11:1, and 11.5:1 emission reduces (CO, CO2, NOx except HC). Additionally, CO2 emissions were found lower in E0 at CR 10.5:1 and also at CR 11.5:1 as compared to E5, E10 and E20. Also, it was observed that blended fuel permits varying CRs without any knock occurrence. Finally, octane numbers are found to be higher with ethanol blends. Keywords: - Ethanol, Octane Number, Combustion, Emissions, knock etc

Experimental and computational study on the enhancement of engine characteristics by hydrogen enrichment in a biogas fuelled spark ignition engine

Limitations on the upgradation of biogas to biomethane in terms of cost effectiveness and technology maturity levels for stationary power generation purpose in rural applications have redirected the research focus towards possibilities for enhancement of biogas fuel quality by blending with superior quality fuels. In this work, the effect of hydrogen enrichment on performance, combustion and emission characteristics of a single-cylinder, four-stroke, water-cooled, biogas fuelled spark-ignition engine operated at the compression ratio of 10:1 and 1500 rpm has been evaluated using experimental and computational (CFD) studies. The percentage share of hydrogen in the inducted biogas fuel mixture was increased from 0 to 30%, and engine characteristics with pure methane fuel was considered as a baseline for comparative analysis. The CFD model is developed in Converge CFD software for a better understanding on combustion phenomenon and is validated with experimental data. In addition, the percentage share of hydrogen enrichment which would serve as a compromise between biogas upgradation cost and engine characteristics is also identified. The results of study indicated an enhancement in combustion characteristics (peak in-cylinder pressure increased; COVIMEP reduced from 9.87% to 1.66%; flame initiation and combustion durations reduced) and emission characteristics (hydrocarbon emissions reduced, and NOx emissions increased but still lower than pure methane) with increase in hydrogen share from 0 to 30% in biogas fuelled SI engine. Flame propagation speed increased and combustion duration reduced with hydrogen supplementation and the same was evident from the results of the CFD model. Performance of the engine increased with increase in hydrogen share up to 20% and further increment in hydrogen share degraded the performance, owing to heat losses and the enhancement in combustion characteristics were relatively small. Overall, it was found that 20% blending of hydrogen in the inducted biogas fuel mixture will be effective in enhancing the engine characteristics of biogas fuelled engines for stationary power generation applications and it holds a good compromise between biogas upgradation cost and engine performance.

Effects of compression and mixing ratio on NH3/H2 fueled Si engine performance, combustion stability, and emission

• NH 3 /H 2 are attractive alternative fuels for the worldwide decarbonization movement. • H 2 is an excellent ammonia additive because it eliminates the cold start problem. • The combustion of ammonia/hydrogen reduces fuel waste while increasing BP. • There are no greenhouse gas emissions from ammonia/hydrogen combustion. • As a result, it appears that fuel NOx predominates over thermal NOx. Carbon-free fuels for the worldwide decarbonization movement are ammonia and hydrogen. The experiment is conducted under WOT conditions with a constant ignition timing of 24°CA BTDC to evaluate performance, combustion stability, and emissions with varying CR (12 to 15), hydrogen energy fractions (5 to 21%), and engine speeds between 1500 and 1700 RPM. BP increased by 31.2% at 1700RPM and BTE increased by 39.0% at 1500RPM, despite a 9% decrease in volumetric efficiency at 1700RPM, from 5% hydrogen fraction at CR12 to 21% hydrogen fraction at CR15.The combustion process is sped up by the effect of hydrogen fraction and CR, causing the flame development and propagation period to shorten. NOx emission was increased significantly with hydrogen and CR, with an increase of 42.34% from 5% hydrogen at CR12 to 21% hydrogen at CR15 at 1700 RPM. Excessive NOx emissions are a drawback that can be successfully controlled by installing after treatment or exhaust gas recirculation technologies. Ammonia is another important key element used to reduce NOx emissions from vehicles because it is used in SCR.