Hydrogen addition to tea seed oil biodiesel: Performance and emission characteristics

Compression ignition engines are the dominant tools of the modern human life especially in the field of transportation. But, the increasing problematic issues such as decreasing reserves and environmental effects of diesel fuels which is the energy source of compression ignition engines forcing researchers to investigate alternative fuels for substitution or decreasing the dependency on fossil fuels. The mostly known alternative fuel is biodiesel fuel and many researchers are investigating the possible raw materials for biodiesel production. Also, hydrogen fuel is an alternative fuel which can be used in compression ignition engines for decreasing fuel consumption and hazardous exhaust emissions by enriching the fuel. In this study, influences of hydrogen enrichment to diesel and diesel tea seed oil biodiesel blends (B10 and B20) were investigated on an unmodified compression ignition engine experimentally. In consequence of the experiments, lower torque and higher brake specific fuel consumption data were measured when the engine was fuelled diesel biodiesel blends (B10 and B20) instead of diesel fuel. Also, diesel biodiesel blends increased CO₂ and NO_x emissions while decreasing the CO emissions. Hydrogen enrichment (5 l/m and 10 l/m) was improved the both torque and brake specific fuel consumption for all test fuels. Furthermore, hydrogen enrichment reduced CO and CO₂ emissions due to absence of carbon atoms in the chemical structure for all test fuels. Increasing flow rate of hydrogen fuel from 5 l/m to 10 l/m further improved performance measures and emitted harmful gases except NO_x. The most significant drawback of the hydrogen enrichment was the increased NO_x emissions.     

Effect of ethanol blending with biodiesel on engine performance and exhaust emissions in a CI engine

The use of biodiesel as an alternative diesel engine fuel is increasing rapidly. However, due to technical deficiencies, they are rarely used purely or with high percentages in unmodified diesel engines. Therefore, in this study, we used ethanol as an additive to research the possible use of higher percentages of biodiesel in an unmodified diesel engine. Commercial diesel fuel, 20% biodiesel and 80% diesel fuel, called here as B20, and 80% biodiesel and 20% ethanol, called here as BE20, were used in a single cylinder, four strokes direct injection diesel engine. The effect of test fuels on engine torque, power, brake specific fuel consumption, brake thermal efficiency, exhaust gas temperature, and CO, CO₂, NO_x and SO₂ emissions was investigated. The experimental results showed that the performance of CI engine was improved with the use of the BE20 especially in comparison to B20. Besides, the exhaust emissions for BE20 were fairly reduced.     

Experimental investigation of control of NOx emissions in biodiesel-fueled compression ignition engine

Biodiesel is an alternative fuel consisting of the alkyl esters of fatty acids from vegetable oils or animal fats. Vegetable oils are produced from numerous oil seed crops (edible and non-edible), e.g., rapeseed oil, linseed oil, rice bran oil, soybean oil, etc. Research has shown that biodiesel-fueled engines produce less carbon monoxide (CO), unburned hydrocarbon (HC), and particulate emissions compared to mineral diesel fuel but higher NO_x emissions. Exhaust gas recirculation (EGR) is effective to reduce NO_x from diesel engines because it lowers the flame temperature and the oxygen concentration in the combustion chamber. However, EGR results in higher particulate matter (PM) emissions. Thus, the drawback of higher NO_x emissions while using biodiesel may be overcome by employing EGR. The objective of current research work is to investigate the usage of biodiesel and EGR simultaneously in order to reduce the emissions of all regulated pollutants from diesel engines. A two-cylinder, air-cooled, constant speed direct injection diesel engine was used for experiments. HCs, NO_x, CO, and opacity of the exhaust gas were measured to estimate the emissions. Various engine performance parameters such as thermal efficiency, brake specific fuel consumption (BSFC), and brake specific energy consumption (BSEC), etc. were calculated from the acquired data. Application of EGR with biodiesel blends resulted in reductions in NO_x emissions without any significant penalty in PM emissions or BSEC.     

The effects of turbocharger on the performance and exhaust emissions of a diesel engine fuelled with biodiesel

This paper investigates the effects of turbocharger on the performance of a diesel engine using diesel fuel and biodiesel in terms of brake power, torque, brake specific consumption and thermal efficiency, as well as CO and NO_x emissions. For this aim, a naturally aspirated four-stroke direct injection diesel engine was tested with diesel fuel and neat biodiesel, which is rapeseed oil methyl ester, at full load conditions at the speeds between 1200 and 2400 rpm with intervals of 200 rpm. Then, a turbocharger system was installed on the engine and the tests were repeated for both fuel cases. The evaluation of experimental data showed that the brake thermal efficiency of biodiesel was slightly higher than that of diesel fuel in both naturally aspirated and turbocharged conditions, while biodiesel yielded slightly lower brake power and torque along with higher fuel consumption values. It was also observed that emissions of CO in the operations with biodiesel were lower than those in the operations with diesel fuel, whereas NO_x emission in biodiesel operation was higher. This study reveals that the use of biodiesel improves the performance parameters and decreases CO emissions of the turbocharged engine compared to diesel fuel.     

Biodiesel production from inedible animal tallow and an experimental investigation of its use as alternative fuel in a direct injection diesel engine

In this study, a substitute fuel for diesel engines was produced from inedible animal tallow and its usability was investigated as pure biodiesel and its blends with petroleum diesel fuel in a diesel engine. Tallow methyl ester as biodiesel fuel was prepared by base-catalyzed transesterification of the fat with methanol in the presence of NaOH as catalyst. Fuel properties of methyl ester, diesel fuel and blends of them (5%, 20% and 50% by volume) were determined. Viscosity and density of fatty acid methyl ester have been found to meet ASTM D6751 and EN 14214 specifications. Viscosity and density of tallow methyl esters are found to be very close to that of diesel. The calorific value of biodiesel is found to be slightly lower than that of diesel. An experimental study was carried out in order to investigate of its usability as alternative fuel of tallow methyl ester in a direct injection diesel engine. It was observed that the addition of biodiesel to the diesel fuel decreases the effective efficiency of engine and increases the specific fuel consumption. This is due to the lower heating value of biodiesel compared to diesel fuel. However, the effective engine power was comparable by biodiesel compared with diesel fuel. Emissions of carbon monoxide (CO), oxides of nitrogen (NO_x), sulphur dioxide (SO₂) and smoke opacity were reduced around 15%, 38.5%, 72.7% and 56.8%, respectively, in case of tallow methyl esters (B100) compared to diesel fuel. Besides, the lowest CO, NO_x emissions and the highest exhaust temperature were obtained for B20 among all other fuels. The reductions in exhaust emissions made tallow methyl esters and its blends, especially B20 a suitable alternative fuel for diesel and thus could help in controlling air pollution. Based on this study, animal tallow methyl esters and its blends with petroleum diesel fuel can be used a substitute for diesel in direct injection diesel engines without any engine modification.     

Performance and emission analysis of cottonseed oil methyl ester in a diesel engine

In this study, performance and emissions of cottonseed oil methyl ester in a diesel engine was experimentally investigated. For the study, cottonseed oil methyl ester (CSOME) was added to diesel fuel, numbered D2, by volume of 5%(B5), 20%(B20), 50%(B50) and 75%(B75) as well as pure CSOME (B100). Fuels were tested in a single cylinder, direct injection, air cooled diesel engine. The effects of CSOME-diesel blends on engine performance and exhaust emissions were examined at various engine speeds and full loaded engine. The effect of B5, B20, B50, B75, B100 and D2 on the engine power, engine torque, bsfc's and exhaust gasses temperature were clarified by the performance tests. The influences of blends on CO, NO_x, SO₂ and smoke opacity were investigated by emission tests. The experimental results showed that the use of the lower blends (B5) slightly increases the engine torque at medium and higher speeds in compression ignition engines. However, there were no significant differences in performance values of B5, B20 and diesel fuel. Also with the increase of the biodiesel in blends, the exhaust emissions were reduced. The experimental results showed that the lower contents of CSOME in the blends can partially be substituted for the diesel fuel without any modifications in diesel engines.     

Physico-chemical properties of ethanol–diesel blend fuel and its effect on performance and emissions of diesel engines

The effects of different ethanol–diesel blended fuels on the performance and emissions of diesel engines have been evaluated experimentally and compared in this paper. The purpose of this project is to find the optimum percentage of ethanol that gives simultaneously better performance and lower emissions. The experiments were conducted on a water-cooled single-cylinder Direct Injection (DI) diesel engine using 0% (neat diesel fuel), 5% (E5–D), 10% (E10–D), 15% (E15–D), and 20% (E20–D) ethanol–diesel blended fuels. With the same rated power for different blended fuels and pure diesel fuel, the engine performance parameters (including power, torque, fuel consumption, and exhaust temperature) and exhaust emissions [Bosch smoke number, CO, NO_x, total hydrocarbon (THC)] were measured. The results indicate that: the brake specific fuel consumption and brake thermal efficiency increased with an increase of ethanol contents in the blended fuel at overall operating conditions; smoke emissions decreased with ethanol–diesel blended fuel, especially with E10–D and E15–D. CO and NO_x emissions reduced for ethanol–diesel blends, but THC increased significantly when compared to neat diesel fuel.     

Diesterol: An environment-friendly IC engine fuel

Diesterol is a new specific term which denotes a mixture of fossil diesel fuel (D), vegetable oil methyl ester called biodiesel (B) and plant derived ethanol (E). In the context of the present paper, this term refers specifically to the combination of diesel fuel, bioethanol produced from potato waste, dehydrated in a vapor phase using 3A Zeolite, and sunflower methyl ester produced through transesterification. The mixture of DBE, i.e. diesterol, was patented under the Iranian patent No. 39407, dated 12-3-2007. The main purpose of this research work was to reduce engine exhaust NO_x, CO, HC and smoke emissions due to application of biofuel and the increase of fuel oxygen content. It was needed to prepare suitable low cost and renewable additives. The diesterol properties such as pour point, viscosity, flash point, copper strip corrosion, ash content, sulfur content and cetane number were determined experimentally. The optimum ratio of bioethanol and biodiesel was found to be 40/60 considering fuel oxygen content, fuel price and mixture properties. Bioethanol was added to enhance the oxygenated component in the fuel, while the sunflower methyl ester was added to maintain the fuel stability at low temperatures. The parameters considered for investigation are the engine power, torque, specific fuel consumption and exhaust emissions for various mixture proportions. The experimental results showed that bioethanol plays an important role in determining the flash point of the blends. By adding 3% bioethanol to diesel and sunflower methyl ester, the flash point was reduced by 16 °C. The viscosity of the blend was also reduced by increasing the amount of bioethanol. The sulfur content of bioethanol and sunflower methyl ester is very low compared to diesel fuel. The sulfur content of diesel is 500 ppm whereas that of bioethanol and sunflower methyl ester is 0 and 15 ppm, respectively. This lower sulfur content is another factor enhancing the use of fuel blends in diesel engines. The bioethanol and sunflower methyl ester combination has sulfur content less than 20 ppm. The maximum power and torque using diesel fuel were 17.75 kW and 64.2 Nm at 3600 and 2400 rpm, respectively. Adding oxygenated compounds to the new blend seems to slightly reduce the engine power and torque and increased the average sfc for various speeds. The experimental measurement and observation of smoke concentration, NO_x, CO and HC concentration indicated that both of these pollutants reduced by increasing the biofuel composition of diesterol throughout the engine operating range.     

Engine performance and emissions of a diesel engine operating on diesel-RME (rapeseed methyl ester) blends with EGR (exhaust gas recirculation)

The effects of biodiesel (rapeseed methyl ester, RME) and different diesel/RME blends on the diesel engine NO_x emissions, smoke, fuel consumption, engine efficiency, cylinder pressure and net heat release rate are analysed and presented. The combustion of RME as pure fuel or blended with diesel in an unmodified engine results in advanced combustion, reduced ignition delay and increased heat release rate in the initial uncontrolled premixed combustion phase. The increased in-cylinder pressure and temperature lead to increased NO_x emissions while the more advanced combustion assists in the reduction of smoke compared to pure diesel combustion. The lower calorific value of RME results in increased fuel consumption but the engine thermal efficiency is not affected significantly. When similar percentages (% by volume) of exhaust gas recirculation (EGR) are used in the cases of diesel and RME, NO_x emissions are reduced to similar values, but the smoke emissions are significantly lower in the case of RME. The retardation of the injection timing in the case of pure RME and 50/50 (by volume) blend with diesel results in further reduction of NO_x at a cost of small increases of smoke and fuel consumption.     

Air nanobubble-enhanced combustion study using mustard biodiesel in a common rail direct injection engine

Though the biodiesel is environmental friendly than the conventional petroleum diesel in the aspects of better combustion quality due to higher cetane number (up to 65), reduced emission, and reduced air pollution, running the common rail direct injection (CRDI) engine with 100% biodiesel is not viable due to NO_x and CO emissions. The present experimental investigation revealed that the above difficulty can be controlled by running CRDI engine with air nanobubble (ANBs)-enabled biodiesel. The results indicated that there was a reduction of 25% in brake-specific fuel consumption, 33% in NO_x, and 16% in CO due to the addition of ANBs with mustard oil biodiesel.     

Biodiesel production from waste chicken fat based sources and evaluation with Mg based additive in a diesel engine

In this study, chicken fat biodiesel with synthetic Mg additive was studied in a single-cylinder, direct injection (DI) diesel engine and its effects on engine performance and exhaust emissions were studied. A two-step catalytic process was chosen for the synthesis of the biodiesel. Methanol, sulphuric acid and sodium hydroxide catalyst were used in the reaction. To determine their effects on viscosity and flash point of the biodiesel, reaction temperature, methanol ratio, type and amount of catalyst were varied as independent parameters. Organic based synthetic magnesium additive was doped into the biodiesel blend by 12 μmol Mg. Engine tests were run with diesel fuel (EN 590) and a blend of 10% chicken fat biodiesel and diesel fuel (B10) at full load operating conditions and different engine speeds from 1800 to 3000 rpm. The results showed that, the engine torque was not changed significantly with the addition of 10% chicken fat biodiesel, while the specific fuel consumption increased by 5.2% due to the lower heating value of biodiesel. In-cylinder peak pressure slightly rose and the start of combustion was earlier. CO and smoke emissions decreased by 13% and 9% respectively, but NO_x emission increased by 5%.     

The emission analysis of an IDI diesel engine fueled with methyl ester of waste frying palm oil and its blends

In this study, the exhaust emissions of an unmodified diesel engine fueled with methyl ester of waste frying palm-oil (biodiesel) and its blends with petroleum based diesel fuel (PBDF) were investigated at the full load-variable speed condition. The relationships between the fuel properties and the air–fuel equivalence ratio, fuel line pressure, start of injection (SOI) timing, and ignition delay were also discussed to explain their effects on the emissions. The obtained test results were compared with the reference values which were determined by using PBDF. The results showed that when biodiesel was used in the test engine, the fuel line pressure increased while air–fuel equivalence ratio and ignition delay decreased. These behaviors affected the combustion phenomena of biodiesel which caused to reduction 57% in carbon monoxide (CO) emission, about 40% in unburned hydrocarbon (HC) emission and about 23% in smoke opacity when compared with PBDF. However, NO_x and CO₂ emissions of the biodiesel have showed different behaviors in terms of the engine speed.     

Hydrogen enriched waste oil biodiesel usage in compression ignition engine

In the present study, hydrogen enrichment for biodiesel-diesel blends was evaluated to investigate the performance and emission characteristics of a compression ignition engine. Biodiesel was obtained from waste oil and blended to pure diesel fuel by volume fraction of 0%, 10% and 20%. After that, pure hydrogen was introduced through the intake air at different flow rates. Effects of pure hydrogen on performance and emission characteristics were investigated by evaluating power, torque, specific fuel consumption, CO, CO₂ and NO_x emissions. Experimental study revealed that waste oil biodiesel usage deteriorated performance and emission parameters except CO emissions. However, the enrichment test fuels with hydrogen fuel can improve performance characteristics and emission parameters, whereas it increased NO_x emissions. Brake thermal efficiency and specific fuel consumption were improved when the test fuels enriched with hydrogen gas. Because of absence of carbon atoms in the chemical structure of the hydrogen fuel, hydrogen addition dropped CO and CO₂ emissions but increment in cylinder temperature caused rising in NO_x emissions.     

Combustion performance and emission reduction characteristics of automotive DME engine system

This article is a condensed overview of a dimethyl ether (DME) fuel application for a compression ignition diesel engine. In this review article, the spray, atomization, combustion and exhaust emissions characteristics from a DME-fueled engine are described, as well as the fundamental fuel properties including the vapor pressure, kinematic viscosity, cetane number, and the bulk modulus. DME fuel exists as gas phase at atmospheric state and it must be pressurized to supply the liquid DME to fuel injection system. In addition, DME-fueled engine needs the modification of fuel supply and injection system because the low viscosity of DME caused the leakage. Different fuel properties such as low density, viscosity and higher vapor pressure compared to diesel fuel induced the shorter spray tip penetration, wider cone angle, and smaller droplet size than diesel fuel. The ignition of DME fuel in combustion chamber starts in advance compared to diesel or biodiesel fueled compression ignition engine due to higher cetane number than diesel and biodiesel fuels. In addition, DME combustion is soot-free since it has no carbon–carbon bonds, and has lower HC and CO emissions than that of diesel combustion. The NO_x emission from DME-fueled combustion can be reduced by the application of EGR (exhaust gas recirculation). This article also describes various technologies to reduce NO_x emission from DME-fueled engines, such as the multiple injection strategy and premixed combustion. Finally, the development trends of DME-fueled vehicle are described with various experimental results and discussion for fuel properties, spray atomization characteristics, combustion performance, and exhaust emissions characteristics of DME fuel.     

Study of antioxidant effect on oxidation stability and emissions in a methyl ester of neem oil fuelled DI diesel engine

Biodiesel as an alternative diesel fuel prepared from vegetable oils or animal fats has attracted more and more attention because of its renewable and environmental-friendly nature. But biodiesel undergoes oxidation and degenerate more quickly than mineral diesel. Further several studies report NO_x emissions increases for biodiesel fuel compared with conventional diesel fuel. In this paper, the experimental investigation of the effect of antioxidant additive (Butylated hydroxytoluene) on oxidation stability and NO_x emissions in a methyl ester of neem oil fuelled direct injection diesel engine has been reported. The antioxidant additive is mixed in various proportions (100–400 ppm) with methyl ester of neem oil. The oxidation stability was tested in Rancimat apparatus and emissions, performance in a computerized 4-stroke water-cooled single cylinder diesel engine of 3.5 kW rated power. Results show that the antioxidant additive is effective in increasing the oxidation stability and in controlling the NO_x emissions of methyl ester of neem oil fuelled diesel engines.     

Effect of induction on exhaust gas recirculation and hydrogen gas in compression ignition engine with simarouba oil in dual fuel mode

Biofuels extracted from non-edible oil is sustainable and can be used as an alternative fuel for internal combustion engines. This study presents the performance, emission and combustion characteristic analysis by using simarouba oil (obtained from Simarouba seed) as an alternative fuel along with hydrogen and exhaust gas recirculation (EGR) in a compression ignition (CI) engine operating on dual fuel mode. Simarouba biofuel blend (B20) was prepared on volumetric basis by mixing simarouba oil and diesel in the proportion of 20% and 80% (v/v), respectively. Hydrogen gas was introduced at the flow rate of 2.67 kg/min, and EGR concentration was maintained at 30% of total air introduction. Performance, combustion and emission characteristics analysis were examined with biodiesel (B20), biodiesel with hydrogen substitution and biodiesel, hydrogen with EGR and were compared with neat diesel operation. Results indicate that BTE of the engine operating with biodiesel B20 was decreased when compared to neat diesel operation. However, introducing hydrogen along with B20 blend into the combustion chamber shows a slight increase in the BTE by 1%. NO_x emission was increased to 18.13% with the introduction of hydrogen than that of base fuel (diesel) operation. With the introduction of EGR, there is a significant reduction in NO_x emission due to decrease in in-cylinder temperature by 19.07%. A significant reduction in CO, CO_2, and smoke emissions were also noted with the introduction of both hydrogen and EGR. The ignition delay and combustion duration were increased with the introduction of hydrogen, EGR with biodiesel than neat diesel operation. Hence, the proposed biodiesel B20 with H₂ and EGR combination can be applied as an alternative fuel in CI engines.     

Influence of biodiesel on engine combustion and emission characteristics

This paper discusses the influence of biodiesel on the engine combustion characteristics. The considered fuel is neat biodiesel from rapeseed oil. The considered engine is a bus diesel engine with injection M system. The engine characteristics are obtained by experiments and numerical simulation. The results obtained with biodiesel are compared to those obtained with mineral diesel under various operating regimes. In this way, the influences of biodiesel usage on the injection pressure, injection timing, ignition delay, in-cylinder gas pressure and temperature, heat release rate, exhaust gas temperatures, harmful emissions, specific fuel consumption, and on engine power are analyzed. Furthermore, the relationships among fuel properties, injection and combustion characteristics, harmful emissions, and other engine performance are determined. Special attention is given to possible explanations of higher NO_x emission in spite of lower in-cylinder gas temperature.     

CNG-diesel engine performance and exhaust emission analysis with the aid of artificial neural network

This study investigates the use of artificial neural network (ANN) modelling to predict brake power, torque, break specific fuel consumption (BSFC), and exhaust emissions of a diesel engine modified to operate with a combination of both compressed natural gas CNG and diesel fuels. A single cylinder, four-stroke diesel engine was modified for the present work and was operated at different engine loads and speeds. The experimental results reveal that the mixtures of CNG and diesel fuel provided better engine performance and improved the emission characteristics compared with the pure diesel fuel. For the ANN modelling, the standard back-propagation algorithm was found to be the optimum choice for training the model. A multi-layer perception network was used for non-linear mapping between the input and output parameters. It was found that the ANN model is able to predict the engine performance and exhaust emissions with a correlation coefficient of 0.9884, 0.9838, 0.95707, and 0.9934 for the engine torque, BSFC, NO_x and exhaust temperature, respectively.     

Influence of fuel properties and composition on NOx emissions from biodiesel powered diesel engines: A review

Biodiesel has proved to be an environment friendly alternative fuel for diesel engine because it can alleviate regulated and unregulated exhaust emissions. However, most researchers have observed a significant increase in NO_x emissions with biodiesel when compared to petrodiesel. The exact cause of this increase is still unclear; however, researchers believe that the fuel properties have been shown to effect the emissions of NO_x. The present work reviews the effect of fuel properties and composition on NO_x emissions from biodiesel fuelled engines. The paper is organised in three sections. The first section deals with the NO_x formation mechanisms. In the following section, the reasons for increased NO_x emissions of biodiesel fuel are discussed. After this, the influence of composition and fuel properties on NO_x emissions from biodiesel fuelled engines has been reviewed. Finally, some general conclusions concerning this problem are summarised and further researches are pointed out.     

Influence of advanced injection timing on the performance and emissions of CI engine fueled with ethanol‐blended diesel fuel

Ethanol has been considered as an alternative fuel for diesel engines. On the other hand, injection timing is a major parameter that sensitively affects the engine performance and emissions. Therefore, in this study, the influence of advanced injection timing on the engine performance and exhaust emissions of a single cylinder, naturally aspirated, four stroke, direct injection diesel engine has been experimentally investigated when using ethanol‐blended diesel fuel from 0 to 15% with an increment of 5%. The original injection timing of the engine is 27° crank angle (CA) before top dead center (BTDC). The tests were conducted at three different injection timings (27, 30 and 33° CA BTDC) for 30 Nm constant load at 1800 rpm. The experimental results showed that brake‐specific energy consumption (BSEC), brake‐specific fuel consumption (BSFC), NO_x and CO₂ emissions increased as brake‐thermal efficiency (BTE), smoke, CO and HC emissions decreased with increasing amount of ethanol in the fuel mixture. Comparing the results with those of original injection timing, NO_x emissions increased and smoke, HC and CO emissions decreased for all test fuels at the advanced injection timings. For BSEC, BSFC and BTE, advanced injection timings gave negative results for all test conditions. Copyright © 2008 John Wiley & Sons, Ltd.