Port Fuel Injection Spark Ignition Research Articles

Methanol (M85) Port Fuel-Injected Spark Ignition Motorcycle Engine Development—Part 1: Combustion Optimization for Efficiency Improvement and Emission Reduction

<div>Limited fossil fuel resources and carbonaceous greenhouse gas emissions are two major problems the world faces today. Alternative fuels can effectively power internal combustion engines to address these issues. Methanol can be an alternative to conventional fuels, particularly to displace gasoline in spark ignition engines. The physicochemical properties of methanol are significantly different than baseline gasoline and fuel mixture-aim lambda; hence methanol-fueled engines require modifications in the fuel injection parameters. This study optimized the fuel injection quantity, spark timing, and air–fuel ratio for M85 (85% v/v methanol + 15% v/v gasoline) fueling of a port fuel-injected single-cylinder 500 cc motorcycle test engine. Comparative engine performance, combustion, and emissions analyses were performed for M85 and baseline gasoline. M85-fueled engine exhibited improved combustion characteristics such as higher peak in-cylinder pressure, heat release rate, and cumulative heat release due to higher flame speed and the effect of fuel oxygen. The brake thermal efficiency increased by up to 23% at lower loads and 8% at higher loads for M85 fueling. Carbon monoxide was reduced by 11.4–94% and 46.1–94.4% for M85 w.r.t. baseline gasoline at 2500 and 3500 rpm, respectively, at varying engine loads. Hydrocarbon emissions showed mixed trends for M85 w.r.t. baseline gasoline. Nitric oxide emissions were 4–90.2% higher for M85 w.r.t. baseline gasoline at 2500 rpm, at varying engine loads; however, mixed trends were observed at 1500 and 3500 rpm. Carbon monoxide, hydrocarbons, and nitric oxide emissions were 4.6, 38.9, and 84.3% lower for M85 than baseline gasoline during idling. Overall the M85-fueled motorcycle engine emitted fewer harmful pollutants, indicating its superior environmental sustainability, except for slightly higher NO emission.</div>

Wall Adhesion Characteristics of Fuel Spray under Flow Conditions in Intake Port Fuel Injection Spark Ignition Engines

Wall Adhesion Characteristics of Fuel Spray under Flow Conditions in Intake Port Fuel Injection Spark Ignition Engines

Investigation on injection strategy affecting the mixture formation and combustion of a heavy-duty spark-ignition methanol engine

Methanol is thought as a carbon neutral fuel and one of the most promising alternative fuels for spark-ignition (SI) engine. On the basic combustion theory of SI engines, mixture formation plays an important role in the SI engine performance. However, there is a lack of investigation on the mixture formation process of heavy-duty (HD) port fuel injection (PFI) SI methanol engines. Therefore, experiments and simulations were conducted on a HD PFI SI engine fueled with pure methanol. The effects of the injection timing (αinj) on the mixture formation process, combustion and emission characteristics were investigated. Methanol engine performance can be predicted by the mixture homogeneity which is deeply affected by injection timing. When αinj was 240°CA, 360°CA and 480°CA, there were three typical mixture formation modes, namely “spray”, “premix and spray” and “premix” mode, respectively. The mixture homogeneity increased first and then decreased while the in-cylinder temperature at the spark timing increased monotonically as αinj varied from 240°CA to 480°CA at the interval of 120°CA. The “premix and spray” mode was the optimal mixture formation strategy from the perspective of promoting mixture homogeneity and decreasing the in-cylinder mixture temperature. When αinj was from 120°CA to 300°CA, the leaner mixture around the spark plug and lower mixture prolonged or retarded CA0-10, CA10-90 and CA50. The above combustion characteristics contributed to a lower engine brake thermal efficiency (BTE) at αinj of 120°CA to 300°CA. As αinj varied from 0°CA to 720°CA, HC emissions increased first and then decreased while CO emissions did the opposite. Both HC and CO emissions at αinj of 360°CA were at low levels. The more HC emission was caused by the more regions with the richer mixture in the crevice formed by the piston and liner. The CO emission was determined by the volume of regions with the richer mixture in the combustion chamber and in-cylinder mixture temperature. The “premix and spray” mode should be adopted to improve the BTE and reduce both HC and CO emissions.

Experimental evaluation of performance of heavy-duty SI pure methanol engine with EGR

Because methanol can be synthesized from captured CO2 and green H2, it is a promising alternative fuel for reducing carbon emissions from heavy-duty vehicles. Experiments were conducted on a multi-cylinder port fuel injection spark-ignition (SI) heavy-duty pure methanol engine modified from a natural gas engine. The main objective was to evaluate the performance of a heavy-duty SI pure methanol engine and its improvement over the original natural gas engine. The effects of the exhaust gas recirculation (EGR) rate and spark timing on the brake thermal efficiency (BTE), as well as the NOx, CO and HC emissions, were investigated under a wide range of operating conditions. The experimental results indicated that the pure methanol engine had a BTE of > 40% BTE in a brake mean effective pressure (BMEP) range of 1.27–2.17 MPa at speeds ranging from 1000 to 1700 rpm and that the peak BTE was ∼ 41.4%, which was higher than that of the original natural gas engine by an absolute 3%. The EGR tolerance of methanol engine was high and the coefficient of variation of the indicated mean effective pressure (COVIMEP) could be maintained below 2%, even at 31% EGR. With an increase in the EGR rate, the CO emissions first decreased and then increased. The partial oxidation of unburned methanol contributed to higher CO emissions when the EGR rate reached a critical value. Advancing the spark timing increased the HC emissions at a low EGR because of the lower post-oxidation temperature; however, it reduced the HC emissions at a high EGR rate because of the more stable combustion. At a BMEP above 0.87 MPa, the NOx, HC and CO emissions ranged from 0.055 to 1.185 g/kWh, from 2.4 to 13.05 g/kWh, and from 6.36 to 10.88 g/kWh, respectively. The pure methanol engine had lower NOx and CO emissions but higher HC emissions than the original natural gas engine.

Potential of compression ratio and exhaust gas dilution on improving combustion and nitrogen oxides emission performance on a PFI engine fueled with methanol

Methanol is a promising alternative fuel, and the effects of compression ratio (CR) and exhaust gas recirculation (EGR) of a port fuel injection spark ignition engine modified from a diesel engine fueled with methanol were studied in this paper. The results showed that with the increase of the EGR rate, flame propagation slowed down, heat release rate and the pressure rise rate decreased, and the combustion lag phenomenon was more obvious in the high EGR range. Under light load and high engine speed conditions, the combustion parameters were more sensitive to the variation of EGR rate. Increasing the CR was beneficial to improve combustion stability. Higher CR and introducing exhaust gas into cylinder both can improve break thermal efficiency and fuel economy performance. EGR strategy showed great capacity on reducing NOx emissions. By Taguchi and ANOVA analysis, it was found that higher EGR rate and small CR were benefit for NOx emission, but higher CR was suitable for decreasing BSFC, 17:1 was an optimal CR for this engine. The influence ratio of EGR on NOx emissions reached 88%, and the engine operating condition had the greatest influence on BSFC, followed by EGR rate.

Comprehensive analysis of the combustion of low carbon fuels (hydrogen, methane and coke oven gas) in a spark ignition engine through CFD modeling

The use of low carbon fuels (LCFs) in internal combustion engines is a promising alternative to reduce pollution while achieving high performance through the conversion of the high energy content of the fuels into mechanical energy. However, optimizing the engine design requires deep knowledge of the complex phenomena involved in combustion that depend on the operating conditions and the fuel employed. In this work, computational fluid dynamics (CFD) simulation tools have been used to get insight into the performance of a Volkswagen Polo 1.4L port-fuel injection spark ignition engine that has been fueled with three different LCFs, coke oven gas (COG), a gaseous by-product of coke manufacture, H2 and CH4. The comparison is made in terms of power, pressure, temperature, heat release, flame growth speed, emissions and volumetric efficiency. Simulations in Ansys® Forte® were validated with experiments at the same operating conditions with optimal spark advance, wide open throttle, a wide range of engine speed (2000–5000 rpm) and air-fuel ratio (λ) between 1 and 2. A sensitivity analysis of spark timing has been added to assess its impact on combustion variables. COG, with intermediate flame growth speed, produced the greatest power values but with lower pressure and temperature values at λ = 1.5, reducing the emissions of NO and the wall heat transfer. The useful energy released with COG was up to 16.5% and 5.1% higher than CH4 and H2, respectively. At richer and leaner mixtures (λ = 1 and λ = 2), similar performances were obtained compared to CH4 and H2, combining advantages of both pure fuels and widening the λ operation range without abnormal combustion. Therefore, suitable management of the operating conditions maximizes the conversion of the waste stream fuel energy into useful energy while limiting emissions.

Effect of Cylinder-by-Cylinder Variation on Performance and Gaseous Emissions of a PFI Spark Ignition Engine: Experimental and 1D Numerical Study

Combustion stability, engine efficiency and emissions in a multi-cylinder spark-ignition internal combustion engines can be improved through the advanced control and optimization of individual cylinder operation. In this work, experimental and numerical analyses were carried out on a twin-cylinder turbocharged port fuel injection (PFI) spark-ignition engine to evaluate the influence of cylinder-by-cylinder variation on performance and pollutant emissions. In a first stage, experimental tests are performed on the engine at different speed/load points and exhaust gas recirculation (EGR) rates, covering operating conditions typical of Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Measurements highlighted relevant differences in combustion evolution between cylinders, mainly due to non-uniform effective in-cylinder air/fuel ratio. Experimental data are utilized to validate a one-dimensional (1D) engine model, enhanced with user-defined sub-models of turbulence, combustion, heat transfer and noxious emissions. The model shows a satisfactory accuracy in reproducing the combustion evolution in each cylinder and the temperature of exhaust gases at turbine inlet. The pollutant species (HC, CO and NOx) predicted by the model show a good agreement with the ones measured at engine exhaust. Furthermore, the impact of cylinder-by-cylinder variation on gaseous emissions is also satisfactorily reproduced. The novel contribution of present work mainly consists in the extended numerical/experimental analysis on the effects of cylinder-by-cylinder variation on performance and emissions of spark-ignition engines. The proposed numerical methodology represents a valuable tool to support the engine design and calibration, with the aim to improve both performance and emissions.

The influence of n-pentanol blending with gasoline on performance, combustion, and emission behaviors of an SI engine

This experimental research deals with the characteristic work on the performance, combustion, and exhaust pollutants for unleaded gasoline mixed with n-pentanol in the proportion of 5%, 10%, 15%, and 20% (by vol.) of the total quantity. The trials were performed on a 1-cylinder, 4-stroke, water-cooled, port-fuel injection (PFI) spark-ignition (SI) engine loading an AC active dynamometer so as to scrutinize the aforementioned behaviors of n-pentanol. The test fuels (unleaded gasoline, Pt5, Pt10, Pt15, and Pt20) were experimented with at various loads ranging from 1 kW to 5 kW with intervals of 1 kW under 1600 rpm fixed speed. The findings coming from the tests exhibited that the infusion of n-pentanol to gasoline has caused to reducing the HC, CO, CO2, and NO emissions in contrast to the baseline gasoline however, O2 levels were observed to be higher. At all of the engine loads, n-pentanol blends exhibited an improvement in BTE when compared with gasoline by reason of the inherent oxygen concentration of used alcohol. As hoped, the peak in-cylinder pressure and apparent heat release rate (HRR) values for the tested fuel blends were found to be higher than that of UG test fuel. It is to be noticed that the higher-order alcohol namely n-pentanol may be used as a partial replacement for gasoline fuel in the SI engine applications according to the experimental outcomes.

Individual Cylinder Combustion Optimization to Improve Performance and Fuel Consumption of a Small Turbocharged SI Engine

Stringent exhaust emission and fuel consumption regulations impose the need for new solutions for further development of internal combustion engines. With this in mind, a refined control of the combustion process in each cylinder can represent a useful and affordable way to limit cycle-to-cycle and cylinder-to-cylinder variation reducing CO2 emission. In this paper, a twin-cylinder turbocharged Port Fuel Injection–Spark Ignition engine is experimentally and numerically characterized under different operating conditions in order to investigate the influence of cycle-to-cycle variation and cylinder-to-cylinder variability on the combustion and performance. Significant differences in the combustion behavior between cylinders were found, mainly due to a non-uniform effective in-cylinder air/fuel (A/F) ratio. For each cylinder, the coefficients of variation (CoVs) of selected combustion parameters are used to quantify the cyclic dispersion. Experimental-derived CoV correlations representative of the engine behavior are developed, validated against the measurements in various speed/load points and then coupled to an advanced 1D model of the whole engine. The latter is employed to reproduce the experimental findings, taking into account the effects of cycle-to-cycle variation. Once validated, the whole model is applied to optimize single cylinder operation, mainly acting on the spark timing and fuel injection, with the aim to reduce the specific fuel consumption and cyclic dispersion.

Journal Vol – 15 No -7, July 2020 Journal > Journal > Journal Vol – 15 No -7, July 2020 > Page 6 PERFORMANCE AND EMISSION CHARACTERISTICS OF GASOLINE-ETHANOL BLENDS ON PFI-SI ENGINE Authors: D.Vinay Kumar ,G.Samhita Priyadarsini,V.Jagadeesh Babu,Y.Sai Varun Teja, DOI NO: https://doi.org/10.26782/jmcms.2020.07.00051 admin July 26, 2020 Abstract: Alcohol based fuels can be produced from renewable energy sources and

Journal Vol – 15 No -7, July 2020 Journal > Journal > Journal Vol – 15 No -7, July 2020 > Page 6 PERFORMANCE AND EMISSION CHARACTERISTICS OF GASOLINE-ETHANOL BLENDS ON PFI-SI ENGINE Authors: D.Vinay Kumar ,G.Samhita Priyadarsini,V.Jagadeesh Babu,Y.Sai Varun Teja, DOI NO: https://doi.org/10.26782/jmcms.2020.07.00051 admin July 26, 2020 Abstract: Alcohol based fuels can be produced from renewable energy sources and

Comparative performance of coke oven gas, hydrogen and methane in a spark ignition engine

In this study, coke oven gas (COG), a by-product of coke manufacture with a high volumetric percentage of H2 and CH4, has been identified as auxiliary support and promising energy source in stationary internal combustion engines. Engine performance (power and thermal efficiency) and emissions (NOx, CO, CO2 and unburned hydrocarbons) of COG, pure H2 and pure CH4 have been studied on a Volkswagen Polo 1.4 L port-fuel injection spark ignition engine. Experiments have been done at optimal spark advance and wide open throttle, at different speeds (2000–5000 rpm) and various air-fuel ratios (λ) between 1 and 2. The obtained data revealed that COG combines the advantages of pure H2 and pure CH4, widening the λ range of operation from 1 to 2, with very good performance and emissions results comparable to pure gases. Furthermore, it should be highlighted that this approach facilitates the recovery of an industrial waste gas.

Emission Experiment of Intake air Humidification of a Port Fuel Injected Spark Ignition engine

In this study, experimental analysis was carried out to investigate the effect of humidified air induction on emissions of a single cylinder, four stroke, air cooled, Royal Enfield Bullet engine 350cc, with modifications made to assist port fuel injection. Tests have been performed on test engine fuelled with gasoline over a range of engine loads and at rated speed for 75 % and 95 % relative humidity with water injection. The outcomes of the experimental analysis reveal that increasing the intake air humidity from 75 % to 95 % decreased the exhaust emissions of NOx, CO, HC and CO2 at 95% rated load of the engine without much or less impact on the thermal brake efficiency.

Effect of Piston Crevices on the Numerical Simulation of a Heavy-Duty Diesel Engine Retrofitted to Natural-Gas Spark-Ignition Operation

Three-dimensional computational fluid dynamics internal combustion engine simulations that use a simplified combustion model based on the flamelet concept provide acceptable results with minimum computational costs and reasonable running times. Moreover, the simulation can neglect small combustion chamber details such as valve crevices, valve recesses, and piston crevices volume. The missing volumes are usually compensated by changes in the squish volume (i.e., by increasing the clearance height of the model compared to the real engine). This paper documents some of the effects that such an approach would have on the simulated results of the combustion phenomena inside a conventional heavy-duty direct injection compression-ignition engine, which was converted to port fuel injection spark ignition operation. Numerical engine simulations with or without crevice volumes were run using the G-equation combustion model. A proper parameter choice ensured that the numerical results agreed well with the experimental pressure trace and the heat release rate. The results show that including the crevice volume affected the mass of a unburned mixture inside the squish region, which in turn influenced the flame behavior and heat release during late-combustion stages.

Experimental Comparative Study on Performance and Emissions of E85 Adopting Different Injection Approaches in a Turbocharged PFI SI Engine

This study examines the effects of ethanol and gasoline injection mode on the combustion performance and exhaust emissions of a twin cylinder port fuel injection (PFI) spark ignition (SI) engine. Generally, when using gasoline–ethanol blends, alcohol and gasoline are externally mixed with a specified blending ratio. In this activity, ethanol and gasoline were supplied into the intake manifold into two different ways: through two separated low pressure fuel injection systems (Dual-Fuel, DF) and in a blend (mix). The ratio between ethanol and gasoline was fixed at 0.85 by volume (E85). The initial reference conditions were set running the engine with full gasoline at the knock limited spark advance boundary, according to the standard engine calibration. Then E85 was injected and a spark timing sweep was carried out at rich, stoichiometric, and lean conditions. Engine performance and gaseous and particle exhaust emissions were measured. Adding ethanol could remove over-fueling with an increase in thermal efficiency without engine load penalties. Both ethanol and charge leaning resulted in a lowering of CO, HC, and PN emissions. DF injection promoted a faster evaporation of gasoline than in blend, shortening the combustion duration with a slight increase in THC and PN emissions compared to the mix mode.

Performance and emission characteristics of a port fuel injected, spark ignition engine fueled by compressed natural gas

This paper presents an experimental study of the performance and emission characteristics of a port fuel injection spark ignition engine modified to fuel by compressed natural gas (CNG). Consequently, the original fuel supply system of the test engine was modified to flexibly run on either gasoline or CNG. The experiment was conducted to compare operating parameters of the test engine fueled by gasoline and CNG with the same air excess ratio (λ). The study results showed that when fueled by CNG, the brake power of the test engine decreases up to 19% and the brake specific energy consumption (BSEC) increases 14%. However, the exhaust emissions of the test engine fueled by CNG are enhanced dramatically. Indeed, CO2 emissions decrease up to 50%, NOx emissions decrease 20%, especially, CO and HC emissions reduce up to 90% and 96%, respectively. For the application of CNG in real-world conditions for in used vehicles, it is recommended that we have to concentrate to solve the problem related to the low power and high fuel consumption of the original engines fueled by CNG.

Effect of acetone-butanol-ethanol (ABE)–gasoline blends on regulated and unregulated emissions in spark-ignition engine

An experimental study was conducted in a port-fuel injection (PFI) spark-ignition (SI) engine fueled with acetone-butanol-ethanol (ABE) and gasoline. 30 vol% ABE blends with different component ratios (A:B:E = 3:6:1, 6:3:1, and 5:14:1), referred to as ABE(3:6:1)30, ABE(6:3:1)30, and ABE(5:14:1)30, were used as test fuels. Additionally, 30 vol% ethanol and 30% vol.% butanol blended with 70 vol% gasoline, referred to as E30 and B30, respectively, were also used as test fuels. Both the regulated emissions, which include unburned hydrocarbons (UHC), carbon monoxide (CO), and nitrogen oxide (NOx), and unregulated emissions, including acetaldehyde, 1,3-butadiene, benzene, toluene, ethylbenzene, and xylene (BTEX), were investigated under various conditions. The experiments were conducted at an engine speed of 1200 rpm and at engine loads of 3, 4, 5, and 6 bar brake mean effective pressure (BMEP) under various equivalence ratios (φ = 0.83–1.25). The results indicated that ABE(6:3:1)30 had the lowest UHC and CO emissions, with ABE(3:6:1)30 having slightly higher NOx emissions. As for unregulated emissions, B30 showed the highest acetaldehyde emission and ABE(6:3:1)30 had the lowest among all the fuel blends. ABE(3:6:1)30 and ABE(6:3:1)30 showed a reduction in 1,3-butadiene emission. Regarding the BTEX emissions, an overall reduction was observed for all the fuel blends, with ABE(3:6:1)30 having shown the lowest BTEX emissions among all the test fuels. The results indicate that ABE could be used as a promising alternative fuel in SI engines, owing to the reduction in emissions.

Characterization of flame front propagation during early and late combustion for methane-hydrogen fueling of an optically accessible SI engine

In recent years, hybrid and fully electric vehicles have received significant consideration since they represent an alternative sustainable transport to the conventional fossil-fuel powered vehicles. However, a worldwide implementation of this alternative propulsion can induce large and undesirable peak demands in distributed power systems. In this context, natural gas spark ignition engines are a promising form of technology to supply part of the energy demand. The main limitations related to low laminar flame propagation speed and poor lean-burn capabilities of natural gas can be overcome by using hydrogen as additional fuel. In this paper, a comparison was carried out between methane and different CH4/H2 mixtures. Specifically, low levels of hydrogen addition were used (5%, 10%, 20% volumetric basis) in stoichiometric and lean burn conditions. The measurements were carried out in an optically accessible single-cylinder port fuel injection spark ignition engine. Optical measurements were performed to analyze the combustion process with high spatial and temporal resolution. In particular, optical techniques based on 2D-digital imaging with two different combustion chamber views were used. Macroscopic (global) and microscopic (local) post-processing tools were implemented to provide a detailed analysis of the flame front propagation process. Moreover, an in-depth analysis was performed to study the flame penetration in the piston top-land crevice. Exhaust gas emissions were also characterized and linked with thermodynamic and optical data. In order to evaluate the combustion process in similar fluid-dynamic conditions, all measurements were performed under steady-state conditions at fixed engine speed, load and spark advance. All the results highlight fast combustion promotion due to the hydrogen addition. In addition, hydrogen reduces the preferential propagation of the flame in a certain direction and increases the flame front wrinkling. Flame propagation in the top-land crevice region was measured for methane and its blends with hydrogen, which represents an original contribution to the literature. An inverse trend was seen between flame penetration in the crevice and unburned hydrocarbon emissions. Lastly, tests in lean conditions demonstrate the potential to decrease nitrogen oxides emissions when methane and methane-hydrogen blends are used.

Characterization of combustion anomalies in a hydrogen-fueled 1.4 L commercial spark-ignition engine by means of in-cylinder pressure, block-engine vibration, and acoustic measurements

Abnormal combustion phenomena are among the main hurdles for the introduction of hydrogen in the transportation sector through the use of internal combustion engines (ICEs). For that reason the challenge is to guarantee operation free from combustion anomalies at conditions close to the ones giving the best engine output (maximum brake torque and power). To this end, an early and accurate detection of abnormal combustion events is decisive in order to allow the electronic control unit deciding suitable correcting actions. In this work, an automotive size 4-cylinder 1.4 L naturally aspirated port-fuel injection spark ignition Volkswagen engine adapted to run on hydrogen has been investigated. Three distinct methods (in-cylinder pressure, block-engine vibration and acoustic measurements) have been employed to detect abnormal combustion phenomena provoked through the enrichment of the hydrogen-air mixture fed to the cylinders under a wide range of engine speeds (1000–5000 rpm). It has been found that the high-frequency components of the in-cylinder pressure and block engine acceleration signals obtained after a Fourier transform analysis can be used for very sensitive detection of knocking combustion cycles. In the case of the ambient noise measurements, a spectral analysis in terms of third octave bands of the signal recorded by a microphone allowed an accurate characterization. Combustion anomalies could be detected through more intense octave bands at frequencies between 250 Hz and 4 kHz in the case of backfire and between 8 kHz and 20 kHz for knock. Computational fluid dynamics simulations performed indicated that some characteristics of the engine used such as the cylinder valves dimensions and the hydrogen flow rate delivered by the injectors play important roles conditioning the likelihood of suffering backfire events.

Effect of intake swirl on combustion performance in an unthrottled spark ignition engine

A Fully Hydraulic Variable Valve System is described in this article which can achieve continuous variation in valve lift, duration, and timing. The system was installed in a four-cylinder port fuel injection spark ignition engine and achieved unthrottled load control through early intake valve closing. The in-cylinder pressure measured experimentally showed that pumping losses of the unthrottled spark ignition engine at 2000 r/min and 0.189 MPa brake mean effective pressure was reduced by 85.4% compared with the throttled spark ignition engine. However, its slow and unstable combustion reduced the indicated thermal efficiency. Compared with the throttled spark ignition engine, the amount of residual exhaust flowing back into the intake port was greatly reduced at the early stage of the intake process. Consequently, it negatively influenced fuel evaporation and fuel–air mixing processes in the intake port of the port fuel injection spark ignition engine and decreased the flow of in-cylinder gases, which resulted in a low combustion rate. A new centrosymmetric helical valve is proposed in this article to improve the fuel–air mixing and combustion rate of the unthrottled spark ignition engine. The experiments demonstrate that the helical valve can generate a strong intake swirl at small intake valve lift. It helps to increase combustion rate and lower cycle-to-cycle variation, which improves indicated thermal efficiency and fuel economy of the unthrottled spark ignition engine at low load.

An artificial neural network developed for predicting of performance and emissions of a spark ignition engine fueled with butanol–gasoline blends

The engine experiments require multiple tests that are hard, time-consuming, and high cost. Therefore, an artificial neural network model was developed in this study to successfully predict the engine performance and exhaust emissions when a port fuel injection spark ignition engine fueled with n-butanol–gasoline blends (0–60 vol.% n-butanol blended with gasoline referred as G100-B60) under various equivalence ratio. In the artificial neural network model, compression ratio, equivalence ratio, blend percentage, and engine load were used as the input parameters, while engine performance and emissions like brake thermal efficiency, brake-specific fuel consumption, carbon monoxide, unburned hydrocarbons, and nitrogen oxides were used as the output parameters. In comparison between experimental data and predicted results, a correlation coefficient ranging from 0.9929 to 0.9996 and a mean relative error ranging from 0.1943% to 9.9528% were obtained. It is indicated that the developed artificial neural network model was capable of predicting the combustion of n-butanol–gasoline blends due to a commendable accuracy.