Medium Engine Speeds Research Articles

Greenhouse gas emission prediction and impact analysis of dual-fuel engine

This study explored the profound influence of greenhouse gas (GHG) emissions on global climate change by introducing an innovative prediction model. Utilizing a backpropagation (BP) neural network with dual-hidden layer, optimized through simulated annealing particle swarm optimization (SA-PSO), the model predicted emissions from a diesel/natural gas dual-fuel engine at 1500 rpm across four torque levels: 400, 800, 1200, and 1600 N·m. The inputs included engine torque, injection timing, pressure, excess air coefficient, and natural gas substitution ratio, with CO2 and CH4 as outputs. Evaluation metrics—the coefficients of determination (R²) of 0.9975 for CO2 and 0.9951 for CH4, the root mean square error (RMSE) of 0.062 % and 278.04 ppm, and the mean relative error (MRE) of 0.82 % and 5.35 %, respectively—demonstrated the model’s accuracy. A quantitative analysis using the Mean Influence Value (MIV) algorithm showed engine torque’s pivotal role in emissions at a medium engine speed with contribution rates of 48.5 % and 40.3 % for CO2 and CH4 emissions, respectively. Notably, at a lower load condition (engine torque = 400 N·m), the natural gas substitution ratio was identified as having the most substantial impact on emissions. This study presents a novel approach to predicting and reducing GHG emissions from dual-fuel engines.

Experimental Study of the Effect of Roller Shape Variations on the CVT System using Petrol-Pyrolytic Fuels toward the Power Characteristics of Automatic Motorcycles

There are two types of two-wheeled vehicles when viewed from the transmission system: manual and automatic. The automatic transmission circuit on the automatic motor, the roller (ballast), is on the primary pulley. In the market, various rollers (weights) are sold, starting from those that are standard and different from the standard with lighter or heavier weight variations. However, there are also aftermarket rollers produced in several automotive industries, one of which is UNIONMATERIAL. The difference lies in the shape and materials used. This study aims to analyze the effect of variations in the shape of the roller on the characteristics of power transmission on automatic motorcycles. The type of vehicle used is a motorcycle produced in 2009 using a dyno test test with two test methods. The first test is from low engine speed ± 1400-1600 rpm to 9000 rpm, while the second test is from medium engine speed ± 4000 rpm to 9000 rpm. In addition, the fuel consumption test was also carried out. The variation used is a roller shape consisting of a round roller, a sliding roller, and a flying roller weighing 12 grams. The highest results obtained at a power of 0.7 HP occurred on the flying roller with 7.1 HP/ 3916 rpm, while the torque was 5.19 N.m on the flying roller (23.96 N·m/1250 rpm). There is an effect on fuel consumption, but not too significant. The biggest difference occurred in the engine parameter RPM 5000 of 0.1 between the flying roller (0.9 L/h) and sliding roller (0.9 L/h) with the round roller (1 L/h) - this happens because the shape of the flying roller is not cylindrical and more dynamic, which is adapted to the movable drive face. There is an additional wing on the roller weight. The data from the results of this study have implications for increasing vehicle performance without changing engine capacity, which requires large costs.

Dimethyl ether fuel injection system development for a compression ignition engine for increasing the thermal efficiency and reducing emissions

In this study, a dedicated fuel injection equipment (FIE) for a 100% dimethyl ether (DME)-fueled three-cylinder engine was developed. DME has a cetane number (>55) higher than baseline diesel (40–50), making it a promising compression ignition (CI) engine fuel. However, some physicochemical properties of DME, namely lubricity, viscosity, density, calorific value, vapour pressure, incompatibility with elastomers, etc., necessitate modifications in the existing FIE to deliver a power output equivalent to baseline diesel fuelled engine. Modifications included customized DME storage tanks, supply lines, return lines, and a pneumatic pre-supply feed pump. In addition, a customized high-pressure pump (HPP) (inline mechanical pump) and a set of modified injectors with larger nozzle hole diameters were used for the DME engine. The engine speed was varied from 1000 to 2000 rpm, and off-road operating conditions were simulated using a non-road steady cycle (NRSC). A detailed evaluation of the FIE for its comparative combustion, performance, and emissions characteristics of DME was conducted vis-à-vis baseline diesel. The DME-fuelled engine showed an increase of ∼4.7% in brake thermal efficiency (BTE) under full load conditions and an increase of ∼8.32% BTE under simulated non-road-testing conditions. In addition, the DME-fuelled engine exhibited no visible smoke and negligible soot in the engine exhaust. DME combustion reduced HC emissions by ∼50% at low and medium engine speeds, and a ∼100% reduction was seen at higher engine speeds compared to baseline diesel engine. The CO emission decreased by ∼90%, and the CO2 emissions were ∼15% lower for DME. Lower exhaust gas temperature (EGT) and lower heat release rate (HRR) during premixed combustion indicated that DME-fuelled engine acted as a low heat rejection (LHR) engine. This study demonstrated a 100% DME-fueled engine with a customized FIE, delivering higher thermal efficiency and lower emissions than conventional diesel engines for on- and off-road applications.

Influence of desulfurization strategies for methane gaseous direct injection engine on carbon dioxide emissions

The use of fuels produced with renewable electricity from wind and solar energy and with CO2 from unavoidable sources or directly captured form the air (so called e-Fuels) is of great interest as a proposition for further limiting the climate impact of road transportation. One of the most efficiently producible e-fuels is e-methane. Feeding methane from renewable sources into the gas grid is one of the most promising pathways to achieve carbon neutral road transportation on a well-to-wheel (WTW) basis. Currently, the use of odorants is mandatory in the gas grid. It is common that sulfur compounds are used as odorants, which can lead to sulfur poisoning of the catalytic converters if an internal combustion engine is operated with it. Consequently, desulfurization will be necessary to maintain high catalyst efficiency over lifetime, which will increase the tank-to-wheel (TTW) CO2 emissions through increased fuel consumption. For desulfurization, it is necessary to increase the catalyst brick temperature to levels above 800 °C. This paper investigates how such high temperatures can be realized and derive implications on engine operation and gas grid regulation. To this end, experimental studies were conducted with a 1-liter 3-cylinder prototype engine from Ford-Werke GmbH featuring variable intake valve timing, a compression ratio of 14 and a turbocharger with variable turbine geometry (VTG). The engine was operated with gas direct injection at up to 16 bar pressure. The ECU software allowed to apply deliberate oscillations of the lambda signal (“wobbling” of the air/fuel ratio) and cylinder individual air/fuel ratios to achieve a sufficient exhaust aftertreatment. The three-way-catalyst for the investigations were particularly suitable for methane operation due to a high palladium loading and increased oxygen storage capacity of the washcoat. Different load points were used for the investigations, ranging from near idle to medium engine speed and load. The catalyst brick temperature was increased considerably by splitting the mean air/fuel ratio between lean and rich operation on different cylinders (so called “lambda spli”), which is limited by the ignition limits of air/methane charges. Furthermore, too extreme lambda split leads to unstable engine operation. Sufficient hydrocarbon reduction can be achieved at a catalyst brick temperature above 500 °C, which cannot be achieved for near idle load points without additional measures (e.g. electrically heated catalyst). Desulfurization of the catalyst requires brick temperatures above 800 °C and is accordingly not achievable with stable engine operation in a significantly large area of the low load operation conditions. In this case additional heating measures (as e.g. electrically heated catalysts or exhaust burner) or vehicle hybridization are required to avoid low load operating conditions and to comply with the emission targets. Furthermore, desulfurization causes 6 % additional CO2 emissions in the WLTP cycle for C-segment passenger cars.

Performance Estimation of a Downsized SI Engine Running with Hydrogen

Hydrogen is a carbon-free fuel that can be produced in many ways starting from different sources. Its use as a fuel in internal combustion engines could be a method of significantly reducing their environmental impact. In spark-ignition (SI) engines, lean hydrogen–air mixtures can be burnt. When a gaseous fuel like hydrogen is port-injected in an SI engine, working with lean mixtures, supercharging becomes very useful in order not to excessively penalize the engine performance. In this work, the performance of a turbocharged PFI spark-ignition engine fueled by hydrogen has been investigated by means of 1-D numerical simulations. The analysis focused on the engine behavior both at full and partial load considering low and medium engine speeds (1500 and 3000 rpm). Equivalence ratios higher than 0.35 have been considered in order to ensure acceptable cycle-to-cycle variations. The constraints that ensure the safety of engine components have also been respected. The results of the analysis provide a guideline able to set up the load control strategy of a SI hydrogen engine based on the variation of the air to fuel ratio, boost pressure, and throttle opening. Furthermore, performance and efficiency of the hydrogen engine have been compared to those of the base gasoline engine. At 1500 and 3000 rpm, except for very low loads, the hydrogen engine load can be regulated by properly combining the equivalence ratio and the boost pressure. At 3000 rpm, the gasoline engine maximum power is not reached but, for each engine load, lean burning allows the hydrogen engine achieving much higher efficiencies than those of the gasoline engine. At full load, the maximum power output decreases from 120 kW to about 97 kW, but the engine efficiency of the hydrogen engine is higher than that of the gasoline one for each full load operating point.

Numerical investigation of the effect of injection timing on the in-cylinder activity of a gasoline direct injection engine

GDI (Gasoline direct injection) technology is used in downsized engines for its economy and low emissions. However, if the injection strategy is not set properly, GDI will produce more emissions than conventional gasoline engines. In this paper, the effect of injection timing on GDI engine emissions under optimal phasing conditions was analyzed by using a three-dimensional (3D) computational fluid dynamics (CFD) GDI engine numerical model. The results showed that at medium engine speed and medium load advancing the injection timing from −300 to −290 CAD ATDC resulted in a more efficient and cleaner combustion process, as evidenced by the higher power output, the increased thermal and combustion efficiencies, and the reduced CO, UHC, soot emissions. The raised NOx emissions at advanced injection timing operation corresponded to the high combustion quality. There was a trade-off relation for advancing injection timing strategy. Specifically, an advanced injection timing operation would increase the amount of liquid film formed on the piston and liner, which is not favorable to clean combustion. However, advancing injection timing also provides more time for fuel-air mixing, which is beneficial for the formation of a more homogeneous mixture. The numerical simulations suggested that the advantages of earlier injection timing outweighed the disadvantages and improved engine efficiency, at least for the conditions and the engine investigated here. Moreover, the comparison indicated that changing injection timing also altered the chemical reaction pathways for pollutant species formation. Overall, all of these findings demonstrated that more fundamental work is still needed to understand the effect of injection timing on engine performance.

Particulate number and size distribution of dimethyl ether/gasoline combined injection spark ignition engines at medium engine speed and load

The understanding of particulate matter emissions from Dimethyl ether (DME)/gasoline combined injection engine is crucial for the application of DME in engines. In this study, the particulate number (PN) and the size distribution of particles from a combined injection spark ignition DME/gasoline engine are studied experimentally. The results show that the addition of DME can effectively reduce both the accumulation and nucleation mode particle numbers for the DME/gasoline engines compared with pure gasoline engines. The distribution of the particle sizes follows a single peak distribution pattern, and the size of the most of particles from DME/gasoline engine are in the nucleation mode, peaking at around 17.8 nm for different ignition timing and DME ratios. Both the nucleation particle numbers (NPN) and accumulation particle numbers (APN) are dependent on the operating conditions investigated in this study and the affecting degree depends on the DME ratios. The accumulation particle numbers (APN) fractions are almost the same for pure gasoline, but the APN fraction increased with the increase of engine load after DME additions.

An assessment of the availability and efficiency of a gasoline fueled spark ignition internal combustion engine

ABSTRACT The energy losses of engines are usually estimated based on the first law of thermodynamics; however, it is incapable to reveal the quality of these losses. In this framework, the engagement of second law analysis (availability) has become progressively attractive. This paper aims to thermodynamically assess the availability and efficiency of a gasoline spark ignition internal combustion engine. For this purpose, a new subroutine of the second law of thermodynamic model was incorporated with an adapted program of the first law of thermodynamic model, which was formerly developed based on the two-zone combustion hypothesis. Details of an experimental setup were employed for model buildup. The measured results were adopted for model validation. In terms of the first law analysis, the modified model was well matched with the experimental observation of the in-cylinder pressure trend. In addition to influence of equivalence ratio and engine speed, analysis was performed to consider not extensively assessed parameters, namely, the combustion duration and residual gas fraction. The results showed that the stoichiometric condition (ϕ = 1) gave the best trends of the availability components. While, these trends were deteriorated as the combustion duration extended, and the residual gas fraction increased. In terms of availability distribution, its lost with exhaust gases was the highest one for all investigated parameters. Furthermore, the medium engine speed, 2000 rpm for current study, was nominated as the optimum operating condition. Maximum levels of engine efficiencies obtained for the first and second laws analyses were about 47.574% and 43.728%, respectively. The developed model can be extending for further evaluation in terms of alternative fuels aspect.

Improving PM-NOx trade-off with paraffinic fuels: A study towards diesel engine optimization with HVO

The current work investigates the impact of a paraffinic fuel on combustion and emissions of a diesel engine, examining alternative injection strategies for the full exploitation of the fuel characteristics. The paraffinic fuel used was the HVO (Hydrotreated Vegetable Oil) produced by Neste Oil with the brand name NEXBTL. The study was conducted on a light-duty turbocharged and aftercooled common-rail diesel engine, with both HVO and a conventional diesel fuel. Four steady-state operating points were examined, at low and medium engine speeds (1500 and 3000 rpm) and loads (35 and 100 Nm), typical of daily driving of a passenger car. The key contribution of the study is a comprehensive analysis of the phenomena influencing the crank angle resolved in-cylinder parameters, as well as interlinking the effects of different variations of injection pressure (default and 300 bar higher), pilot injection timing (default and ± 5°CA) and main injection timing (default and ± 2°CA) on gaseous emissions and particulate matter (PM). The findings have shown that at default engine settings the use of HVO results in up to 40% reduction of engine-out PM and HC emissions without appreciable changes in NOx emissions. The significant reduction of engine-out PM levels, facilitates the adoption of measures for NOx emissions limitation. The latter are reduced by up to 20% when the main injection timing is retarded (by 2° CA in the present study), while PM emissions are still kept well below the respective diesel fuel levels.

Comparison of the Emissions, Noise, and Fuel Consumption Comparison of Direct and Indirect Piezoelectric and Solenoid Injectors in a Low-Compression-Ratio Diesel Engine

An experimental investigation has been carried out to compare the performance and emissions of a low-compression-ratio Euro 5 diesel engine featuring high EGR rates, equipped with different injector technologies, i.e., solenoid, indirect-acting, and direct-acting piezoelectric. The comparisons, performed with reference to a state-of-the-art double fuel injection calibration, i.e., pilot-Main (pM), are presented in terms of engine-out exhaust emissions, combustion noise (CN), and fuel consumption, at low–medium engine speeds and loads. The differences in engine performance and emissions of the solenoidal, indirect-acting, and direct-acting piezoelectric injector setups have been found on the basis of experimental results to mainly depend on the specific features of their hydraulic circuits rather than on the considered injector driving system.

Research on the Combustion, Energy and Emission Parameters of Various Concentration Blends of Hydrotreated Vegetable Oil Biofuel and Diesel Fuel in a Compression-Ignition Engine

This article presents our research results on the physical-chemical and direct injection diesel engine performance parameters when fueled by pure diesel fuel and retail hydrotreated vegetable oil (HVO). This fuel is called NexBTL by NESTE, and this renewable fuel blends with a diesel fuel known as Pro Diesel. A wide range of pure diesel fuel and NexBTL100 blends have been tested and analyzed: pure diesel fuel, pure NexBTL, NexBTL10, NexBTL20, NexBTL30, NexBTL40, NexBTL50, NexBTL70 and NexBTL85. The energy, pollution and in-cylinder parameters were analyzed under medium engine speed (n = 2000 and n = 2500 rpm) and brake torque load regimes (30–120 Nm). AVL BOOST software was used to analyze the heat release characteristics. The analysis of brake specific fuel consumption showed controversial results due to the lower density of NexBTL. The mass fuel consumption decreased by up to 4%, and the volumetric consumption increased by up to approximately 6%. At the same time, the brake thermal efficiency mainly increased by approximately 0.5–1.4%. CO, CO2, NOx, HC and SM were analyzed, and the change in CO was negligible when increasing NexBTL in the fuel blend. Higher SM reduction was achieved while increasing the percentage of NexBTL in the blends.

Comparative Study on the Effects of Ethanol Proportion on the Particle Numbers Emissions in a Combined Injection Engine

Ethanol has significant potential for the reduction of fuel consumption and the emissions of engines. In this paper, a dual-fuel combined engine test rig with ethanol injected in the intake port and gasoline injected directly into the cylinder are developed and the effects of ethanol/gasoline ratio (Re) on the combustion and emission of particle numbers are investigated experimentally. The results indicate that the peak in-cylinder temperature (Tmax) decreases continuously with the increase of the ethanol/gasoline ratio (Re). For particle emissions, ethanol can significantly reduce the accumulation mode particle number (APN) at low engine speed; and the lowest number of particulates are at G25 (the gasoline ratio is 25% of the fuel) at low load. And at high engine load, the total particle number (TPN) is insensitive to speed with large ethanol fraction and TPN is relatively small. With the decrease of Re (Re < 50%), TPN rises sharply. When the direct injection timing advances, TPN reduces continuously and the effects caused by speed can be neglected. On the contrary, the speed has significant effects on particle emissions at various ignition times. At low speed, increasing ignition advance can cause the increase of the TPN; which is contrary to the effects of particle emissions at medium engine speed. And the effect of ignition timing at high speed on particle number is not obvious. The ignition timing for which the lowest TPN is reached will increase with the direct injection timing advances.

Potential for energy and emissions of asymmetric twin-scroll turbocharged diesel engines combining inverse Brayton cycle system

In this paper, a new combined cycle of asymmetric twin-scroll turbocharged diesel engine cycle and inverse Brayton cycle (IBC) for use is proposed. The use of a single asymmetric twin-scroll turbocharged diesel engine cycle is simple in structure and can improve the trade-off between low fuel consumption and nitrogen oxide emissions; however, both the engine exhaust gas recirculation (EGR) rate and the exhaust energy utilization should be further improved. A test bench experiment was performed to validate the numerical models of the single-cycle and combined-cycle approaches. Based on the models, the influence laws of the critical system parameters (turbine asymmetry and the IBC turbine throat area) on the engine performance characteristics were studied. The combined cycle was found to achieve improvements in both the engine EGR rate and the power. Given the same EGR rates at different engine speeds, the power improvement of the combined cycle was found to increase with increasing engine speed and decreasing turbine asymmetry, reaching a maximum of 5.00%. Moreover, further power improvements with an increasing IBC turbine throat area were observed, with the maximum power improvement of 5.78%. Compared with the power turbine, the combined cycle can utilize more waste heat at low and medium engine speeds; thus, the combined cycle is well-suited for use in heavy-duty diesel engines. The new combined cycle described in this report has great potential to provide substantial gains in both engine emissions and energy.

Improving Diesel Engine Efficiency and Emissions Using Fuel Additives

Diesel engine is widely used in the different applications of the modern life. Diesel fuel quality is an important indicator of the engine efficiency and exhaust emissions. However, the low cetane number of the commercial diesel resulting from improper refining processes lead to significant reduction in the engine efficiency. Hence, the aim of this study is to use diethyl ether to improve the fuel quality for better engine performance at lower engine emissions. Diethyl ether has been used at 5% percentage with commercial diesel, and the cetane number of the fuel was measured. Engine test was conducted at increasing speed to evaluate the engine performance and emissions. The study results show an improvement in the fuel cetane number from 49 to 51 with 5% diethyl ether. Furthermore, significant increase in engine power by about 10% has been recorded for the whole engine speed with slightly lower specific fuel consumption at low and medium engine speeds. Moreover, noticeable reduction in NOx emissions and CO emissions has been observed compared to commercial diesel. Therefore, it can be concluded that the utilization of diethyl ether as a fuel additive with commercial diesel can be considered for improving engine efficiency and control exhaust emissions.

NOx emission of biodiesel compared to diesel: Higher or lower?

A little decrease in NOx emission of biodiesel compared to diesel is observed at low loads under low and medium engine speeds. An overall experimental investigation on NOx emission based on combustion characteristics of biodiesel has been carried out. Negative effects of high viscosity and distillation temperature on the spray quality and homogeneity of air fuel mixture are clear at low loads under low and medium speeds. Brake thermal efficiency (BTE) and combustion temperature of biodiesel are lower than those of diesel, resulting in a lower level of NOx emission. With the increase of load, in-cylinder thermal condition and the injection pressure are improved, and with the increase of speed, air swirl movement is strengthened. Oxygenated biodiesel produces more reactive radicals than diesel, and these radicals will surely accelerate the combustion speed, improves the intensity of diffusion combustion, shortens the combustion duration and increase the BTE. Consequently, the diffusion combustion temperature, especially the peak combustion temperature of biodiesel is higher than that of diesel. On the whole, NOx emission of biodiesel is higher than that of diesel in most cases, except in the condition of low loads under low and medium speeds.

Research for intake and exhaust system parameterization of 2-cylinder gasoline engine for RE-EV

Many research groups have attempted to overcome the short travel distance of electric cars by using RE-EVs (range extended electric vehicle) with small engine generators for battery charging. Engines for RE-EVs need to be optimized for maximum power at around medium engine speed or less because a higher engine speed causes higher noise. In this study, basic research about intake and exhaust flow was conducted to find the design point of high power at around medium engine speed. Test parameters are intake valve open (IVO) timing, the shape of the exhaust manifold and the intake runner length for a 0.6-L naturally aspirated (NA) gasoline engine. The firing order of the test engine is from the first cylinder to the second cylinder and cylinders have 180 oCA (crank angle degree) phasing difference. Test conditions are from 1200 to 6000 rpm at full load operation, 12, 22, and 32 oCA BTDC (before top dead center) of IVO timing, and an exhaust manifold to reduce interference of exhaust gas between the first and second cylinder; there are also 200, 340, and 440 mm length intake runners. The effect of the IVO timing on the engine performance was found not to be significant in this study. The shape of the exhaust manifold and the lengthened intake runners affected the torque and the BSFC (brake specific fuel consumption) and helped to improve the engine performance at around medium engine speed.

Effects of hydrogen direct injection on engine stability and optimization of control parameters for a combined injection engine

As engine stability is a crucial issue for engine performance and toxic emissions, an experimental research has been conducted to analyze the effects of hydrogen direct injection on engine stability. The experiments have been divided into two parts. The first set is aimed to analyze different parameter characteristics with and without hydrogen direct injection, and the second set tries to find optimal control regions. Excess air ratios, spark timings, engine speeds and engine loads are chosen as primary parameters in the study. The results show hydrogen addition can increase brake thermal efficiency by a range from 6% to 13%, enhancing the lean burn performance. Combustion duration has been shortened to about 80% by adding 10% hydrogen mixture into gasoline. Besides, Hydrogen addition makes the mixture further insensitive to ignition timings, and narrows the optimal regions with higher excess air ratios. Under medium engine speeds, the highest CoVIMEP locates in the low load region for pure gasoline, while this maximum value appears in the medium load region for 10% hydrogen mixture. In addition, the specific value of CoVIMEP with 10% hydrogen is rather small compared to pure gasoline. Thus, hydrogen direct injection can significantly improve engine stability and reduce controlling difficulties.

Effect of turbo A/R ratio on a high speed turbocharged automotive diesel engine

In light of the recent trend to improve fuel economy and emission control in diesel engines to meet future energy conservation standards a lot of research is being done on turbocharger. The turbines in turbochargers are characterised mainly by A/R ratio. Varying A/R ratios can adversely affect the performance, fuel economy and emissions of a diesel engine due to effects of pressure boost, back pressure and exhaust gas recirculation. The current study deals with influence of A/R ratios of turbochargers on performance and emissions of a two-cylinder diesel engine. It is found from the experiments carried out that oxides of nitrogen emitted from the engine for all tested turbochargers showed the increasing trend from low to medium engine speeds and it is reverse trend from medium to higher speed range. The other engine emissions unburned hydrocarbon, carbon monoxide and smoke showed the inverse trend of oxides of nitrogen.

Study of alcohol fuel of butanol and ethanol effect on the compression ignition (CI) engine performance, combustion and emission characteristic

Diesel engine which is one of the larger contributors to total consumption for petroleum is an attractive power unit used widely in many fields. However, diesel engines are among the main contributors to air pollutions for the large amount of emissions, such as CO, CO2 and NOx lead to an adverse effect on human health. Many researches have been done to find alternative fuels that are clean and efficient. Biodiesel is preferred as an alternative source for diesel engine which produces lower emission of pollutants. This study has focused on the evaluation of diesel and alcohol-diesel fuel properties and also the performance, combustion and exhaust emission from diesel engine fuelled with diesel and alcohol. Butanol and ethanol is blend with diesel fuel at 1:9 ratio. There are three test fuel that is tested which Diesel (100% diesel), D90BU10 (10% Butanol and 90% diesel) and D90E10 (10% Ethanol and 90% diesel). The comparison between diesel and alcohol-diesel blend has been made in terms of fuel properties characterization, engine performance such as brake power (BP) and brake specific fuel consumption (BSFC) also the in cylinder maximum pressure characteristic. Thus, exhaust gas emission of CO, CO2, NOx and O2 emission also has been observed at constant load of 50% but in different operating engine speed (1100 rpm, 1400 rpm, 1700 rpm, 2000 rpm and 2300 rpm). The results show the addition of 10% of each butanol and ethanol to diesel fuel had decreased the fuel density about 0.3% to 0.5% compared to mineral diesel. In addition, viscosity and energy content are also decrease. The addition of 10% butanol had improved the fuel cetane number however the ethanol blends react differently. In term of engine performance, as the engine speed increased, BP output also increase respectively. Hence, the alcohol blends fuel generates lower BP compared to diesel, plus BSFC for all test fuel shows decreasing trend at low and medium speed, however increased gradually at higher engine speed. Thus, D90BU10 had higher BSFC compared to mineral diesel and D90E10. In general, the addition of alcohol blend in diesel fuel had increase the BSFC. In term of in cylinder pressure, as the engine speed is increased, the crank angle noted to move away from TDC for all test fuel. The maximum cylinder pressure increased at low and medium speed, but decrease in higher engine speed. The addition of 10% of butanol and ethanol in the mineral diesel decreased the maximum cylinder pressure. Meanwhile, O2 emission of D90E10 is higher compared to D90BU10 due to higher oxygen content found in ethanol. The CO2 emission of D90BU10 recorded higher compared to mineral diesel due to the high oxygen contents in the alcohol. CO emission of alcohol blend on the other hand had lower emission at higher engine speed compared to mineral diesel. As engine speed is increased, NOx emission of mineral diesel and D90E10 had decreased gradually. However, D90BU10 had increased of NOx emission at lower to medium engine speed, than gradually decreased at higher engine speed.

Effect of fuel injection timing of hydrogen rich syngas augmented with methane in direct-injection spark-ignition engine

The product of gasification of solid biomass, also called syngas is believed to be good fuel for internal combustion engines in the move from the carbon based fuel to zero emission fuels. The only problem is its lower calorific value which is placed at one third of that of compressed natural gas (CNG). There are latest efforts to enhance the hydrogen rich syngas by augmenting it with methane so that the calorific value can be improved. This paper presents experimental results of the effect of the start of fuel injection timing (SOI) on the combustion characteristics, performance and emissions of a direct-injection spark-ignition engine fueled with a 20% methane augmented hydrogen rich syngas of molar ratio of 50% H2 and 50% CO composition. The engine was operated at fully open throttle and the start of fuel injection (SOI) was varied at 90, 120 and 180° before top dead center (BTDC). The experiment was conducted at lean mixture conditions in the low and medium engine speed ranges (1500–2400 RPM). The spark advance was set to the minimum advance for a maximum brake torque in all the test parameters. The methane augmented hydrogen rich syngas was observed to perform well over wide range of operation with SOI = 180°CA BTDC. However, SOI = 120°CA BTDC performed well at lower speeds recording improved performance and emissions. Limitation of operable load was observed for both SOI = 120°CA BTDC and 90°CA BTDC due to an insufficient time for complete injection of fuel at lower relative air–fuel ratio (λ) with higher speeds.