Comparative characteristics of compression ignited engines operating on biodiesel produced from waste vegetable oil

Performance and emission characteristics of two compression ignited engines of different compression ratios, number of cylinders, cooling system, and power output are studied. Waste vegetable oil-derived biofuel is used. Engines are fueled with B0, B20 and B100 mixtures. Thermal efficiency, brake specific consumption and engine emissions (CO, Unburned HC, O₂ and NO) are reported and comparisons are made for fuel mixtures running on both engines. Trends of emissions and performance curves are compared to the literature of the available data. It is noted that the biofuel certainly affects unburned HC emissions regardless of engine specifications and/or operating conditions. However, the type of fuel or adding biofuel to diesel may not affect parameters such as exhaust gas temperature and emissions (CO, Unburned HC, O₂, NO). These parameters may change as functions of engine specifications and operating conditions regardless of biofuel or diesel being used. These findings are supported by separate investigations using different biofuels in literature.     

进气初始条件对柴油机低温燃烧及PAHs排放特性的影响

应用三维CFD模型耦合化学动力学模型的方法,研究了进气初始条件对柴油机低温燃烧及多环芳香烃(PAHs)排放特性的影响规律。结果表明:进气温度降低,滞燃期延长,同时由于进气密度增大,使柴油机的循环进气量增多,空燃比升高,燃油在缸内燃烧更充分,在较低的进气温度工况时缸内生成PAHs各组分相对较低;进气压力升高,PAHs各组分的生成时刻提前,并且PAHs各组分的含量依次减少。燃烧起始阶段,苯(C6H6)主要分布在燃烧室凹坑附近。在燃烧中期与后期,其主要分布在凹坑壁面附近。     

Application potential of vegetable oils as alternative to diesel fuels in compression ignition engines: A review

Vegetable oils have been identified as the promising alternative source to replace fossil based fuel in the compression ignition (CI) engine. It is renewable and possesses characteristics that is similar to that of the diesel. Biodiesel, transesterifiedform of vegetable oil (VO), is now being commercially used in CI engines. However, biodiesel production from VO involves use of alcohols and chemicals which results the need of skilled labor and investment for its production. In view of this, many studies are also being carried out on the direct use of VO in the engine. The direct use of VO oil in engine is as good as that of the diesel. The superior quality of diesel however makes it better performance in engine as compared to the vegetable oil. Preheating and blending of VO are found to be the most common solution to overcome its inferior properties. The use of preheated and blended VO is found to improve the engine overall performance. This paper is focused exclusively on the one-to-one basis of study pertaining to the effect of neat, preheated and blended vegetable oils on diesel engine performance and emission through supplementation of illustrative figures from the various experimental studies.     

植物油及其衍生物在柴油机上的应用

评述了植物油及其衍生物在柴油机上应用的前景和可行性,讨论了目前纯植物油、生物柴油和它们的混合物在柴油机上使用的最新研究成果。比较了植物油及其衍生物和传统柴油的性质以及柴油机燃用这些燃料时的性能和排放特性。     

The comparison of engine performance and exhaust emission characteristics of sesame oil–diesel fuel mixture with diesel fuel in a direct injection diesel engine

The use of vegetable oils as a fuel in diesel engines causes some problems due to their high viscosity compared with conventional diesel fuel. Various techniques and methods are used to solve the problems resulting from high viscosity. One of these techniques is fuel blending. In this study, a blend of 50% sesame oil and 50% diesel fuel was used as an alternative fuel in a direct injection diesel engine. Engine performance and exhaust emissions were investigated and compared with the ordinary diesel fuel in a diesel engine. The experimental results show that the engine power and torque of the mixture of sesame oil–diesel fuel are close to the values obtained from diesel fuel and the amounts of exhaust emissions are lower than those of diesel fuel. Hence, it is seen that blend of sesame oil and diesel fuel can be used as an alternative fuel successfully in a diesel engine without any modification and also it is an environmental friendly fuel in terms of emission parameters.     

Effects of turpentine and gasoline-like fuel obtained from waste lubrication oil on engine performance and exhaust emission

In this study, an experimental investigation was carried out to determine the effects of gasoline-like fuel (GLF), and its blends with turpentine with ratios of 10%, 20%, and 30% on the performance and emission characteristics of a gasoline engine. The GLF was obtained from waste lubrication engine oil by the method of pyrolitic distillation. Characteristics of the pure GLF and its blends were tested. A series of engine performance and emission tests were conducted using the fuel samples in the test engine. Performance parameters for each test were calculated utilizing measurement values of force exerted on the crank shaft, rate of air and fuel mass flow to the engine and engine speed. Effects of the fuels on the performance parameters, exhaust gas temperature, and emissions of NOx, CO, CO₂, and HC were discussed. The results indicated that torque, brake mean effective pressure and thermal efficiency increased but brake specific fuel consumption decreased with increasing amount of turpentine in the GLF sample. The main effect of 10%, 20% and 30% turpentine additions to GLF on pollutant formation was that the NOx ratio increased, whereas that of CO decreased.     

柴油机富氧燃烧排放特性的试验研究

介绍了在S195柴油机上进行富氧燃烧的试验，对柴油机排放特性进行了比较与分析，目的是通过试验研究，找到在富氧条件下同时降低碳烟和NOx排放的方法。研究结果表明，增加进气氧的质量分数，碳烟排放大幅度下降，HC和CO也趋于下降，但NOx排放显增加；推迟供油提前角，可以使NOx排放降低，但碳烟有上升趋势，HC和CO排放增加。所以，采用富氧燃烧时必须同时推迟供油提前角，才能获得较低的排放量组合。     

A critical review: Application of methanol as a fuel for internal combustion engines and effects of blending methanol with diesel/biodiesel/ethanol on performance,emission, and combustion characteristics of engines

This article presents a comprehensive overview of methanol as a potential oxygenated fuel for internal combustion engines. Here two approaches have been examined to evaluate the utilization of methanol, namely blending with diesel/biodiesel/methanol and premixing with intake air or fumigation. In conventional compression ignition engines, up to 95% and 25% diesel can be replaced by methanol through fumigation and blending, respectively. Higher latent heat of vaporization of alcohol led to lower peak in-cylinder pressure and NO_x; however, it negatively affects thermal efficiency and hydrocarbon and carbon monoxide emissions. Fumigation of alcohol requires modifications in the existing engine, whereas blending needed surfactants or additives to produce stable alcohol–diesel blends. High injection pressure and late direct injection, methanol–diesel blends have shown lower emissions and proved their potential as a suitable replacement for ethanol–diesel blends from the components durability perspective.     

Direct injection diesel engine performance,emission, and combustion characteristics using diesel fuel,nonedible honne oil methyl ester,and blends with diesel fuel

Honne oil methyl ester (HOME) is produced from a nonedible vegetable oil, namely, honne oil, available abundantly in India. It has remained as an untapped new possible source of alternative fuel that can be used for diesel engines. The present research is aimed at investigating experimentally the performance, exhaust emission, and combustion characteristics of a direct injection diesel engine (single cylinder, water cooled) typically used in agricultural sector over the entire load range when fuelled with HOME and diesel fuel blends, HM20 (20% HOME + 80% diesel fuel)–HM100. The properties of these blends are found to be comparable with diesel fuel conforming to the American and European standards. The combustion parameters of HM20 are found to be slightly better than neat diesel (ND). For other blend ratios, these combustion parameters deviated compared with ND. The performance (brake thermal efficiency (BTE), brake‐specific fuel consumption, and exhaust gas temperature) of HM20 is better than ND. For other blend ratios, BTE is inferior compared with ND. The emissions (CO and SO) of HM20–HM100, throughout the entire load range, are dropped significantly compared with ND. Unburned hydrocarbon emissions of HM20–HM40, throughout the entire load range, is slightly decreased, whereas for other blend ratios, it is increased compared with ND. NO_x emissions of HM20, throughout the entire load range, is slightly increased, whereas for other blend ratios, it is slightly decreased. The reductions in exhaust emissions together with increase in BTE made the blend HM20 a suitable alternative fuel for diesel fuel and thus could help in controlling air pollution. Copyright © 2011 John Wiley & Sons, Ltd.     

Emission and performance characteristics of an indirect ignition diesel engine fuelled with waste cooking oil

Biofuel has so far been backed by government policies in the quest for low carbon fuel in the near future and promises to ensure energy security through partially replacing fossil fuels. At present biodiesel is mostly produced by transesterification reaction from oil-seed feedstock and has to conform to ASTM D6751 specifications. Biodiesel sustainability has sparked debate on the pros and cons of biodiesel and the question of food security. The use of waste cooking oil such as palm and coconut oil in diesel engines is more sustainable if they can perform similarly to ordinary diesel fuel (B0). This paper presents the experimental study carried out to evaluate emission and performance characteristics of a multi-cylinder diesel engine operating on waste cooking oil such as 5% palm oil with 95% ordinary diesel fuel (P5) and 5% coconut oil with 95% ordinary diesel fuel (C5). B0 was used for comparison purposes. The results show that there are reductions in brake power of 1.2% and 0.7% for P5 and C5 respectively compared with B0. In addition, reduction of exhaust emissions such as unburned hydrocarbon (HC), smoke, carbon mono-oxide (CO), and nitrogen oxides (NO_x) is offered by the blended fuels.     

Effect of hydrogen addition to intake gas on combustion and exhaust emission characteristics of a diesel engine

The present study experimentally investigated the performance and emission characteristics of the diesel engine with hydrogen added to the intake air at late diesel-fuel injection timings. The diesel-fuel injection timing and the hydrogen fraction in the intake mixture were varied while the available heat produced by diesel-fuel and hydrogen per second of diesel fuel and hydrogen was kept constant at a certain value. NO showed minimum at specific hydrogen fraction. The maximum rate of incylinder pressure rise also showed minimum at 10 vol. % hydrogen fraction. However, it is desirable to set the maximum rate of incylinder pressure rise less than 0.5 MPa/deg. to realize low level of combustion noise and NO emission. We attempt to reduce further NO and smoke emissions by EGR. As the result, in the case of the diesel-fuel injection timing of −2 °. ATDC with 3.9 vol. % hydrogen addition, the smoke emission value was 0%, NO emission was low, the cyclic variation was low, and the maximum rate of incylinder pressure rise was acceptable under a nearly stoichiometric condition without sacrificing indicated thermal efficiency.     

Studies on the comparison of performance and emission characteristics of a diesel engine using three degummed non-edible vegetable oils

This paper investigates non-edible straight vegetable oils of Putranjiva, Jatropha and Karanja to find out the most suitable alternative diesel by a chemical processing. Degumming is an economical chemical process that is done by concentrated phosphoric acid. This process is applied to the above-mentioned non-edible oils to remove the impurities for the improvement of viscosity, cetane number and better combustion in the diesel engine upto certain blend of diesel and non-edible vegetable oils. Ten percent, 20%, 30% and 40% blends of degummed non-edible oils and diesel are used in a Ricardo variable compression engine to study and compare the performance and emission characteristics. It is observed that the non-edible oil of Jatropha gives the best results related to the performance and emissions at high loads and 45° bTDC injection timing.     

Emission and engine performance analysis of a diesel engine using hydrogen enriched pomegranate seed oil biodiesel

The aim of this study is to determine the availability of pomegranate seed oil biodiesel (POB) as an alternative fuel in diesel engines and evaluate engine performance and emission characteristics of pure hydrogen enriched POB using diesel engine. For this purpose, the intake manifold of the test engine was modified and hydrogen enriched intake air was supplied throughout the experiments. Physical properties of POB and its blend with diesel fuel were also determined. The results showed that measured physical properties of POB are comparable with diesel fuel. According to engine performance experiments, although POB utilization has slight undesirable effects on some engine performance parameters such as brake power output and specific fuel consumption, it can be used as alternative fuel in diesel engines, by this way CO emission can be improved. Finally, hydrogen enrichment experiments indicated that pure hydrogen addition causes a slight improvement in both engine performance and exhaust emissions.     

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.     

Durability studies of mono-cylinder compression ignition engines operating with diesel, soy and castor oil methyl esters

There are many studies showing that the performance results for engines operating with biofuels are acceptable, although very few long-term analysis of wear and maintenance problems are shown. Three mono-cylinder compression ignition engines were tested for approximately 1000 h each, with pure diesel oil (D100), pure soy methyl ester (SME100) and pure castor oil methyl ester (CME100). The lubricating oil analysis didn’t reveal any excessive amount of metals compared to the engine with pure diesel. Viscosity decreased very soon to values below the minimum recommended due to dilution with the methyl esters, especially with SME100. The injection system analysis showed that opening pressures, hydraulic flux and corrosion levels were acceptable. The SME piston showed a very small crack. A higher amount of carbon deposits and gum formation was found over biofuel pistons, indicating poor combustion. Piston ring seating and gap were inside specification. Cylinder liners presented no damage on running surface. The valves presented abrasive and adhesive wear, contact fatigue for SME100 and marks at valve seating for CME100, considered acceptable after 1000 h of test. The results obtained show that the use of pure methyl esters fuels was acceptable for these engines regarding wear and maintenance problems.     

Influence of hydrogen co-combustion with diesel fuel on performance,smoke and combustion phases in the compression ignition engine

The main objective of this study was to examine impact of hydrogen addition to the compression ignition engine fueled with either rapeseed methyl ester (RME) or 7% RME blended diesel fuel (RME7) on combustion phases and ignition delay as well as smoke and exhaust toxic emissions. Literature review shows in general, hydrogen in those cases is used in small amounts below lower flammability limits. Novelty of this work is in applying hydrogen at amounts up to 44% by energy as secondary fuel to the compression ignition engine. Results from experiments show that increase of hydrogen into the engine makes ignition delay shortened that also affects main combustion phase. In all tests the trends of exhaust HC and CO toxic emissions vs. hydrogen addition were negative. The trend of smokiness decreased steadily with increase of hydrogen. Amounts of hydrogen addition by energy share were limited to nearly 35% due to combustion knock occurring at nominal load.     

Effects of preheating of crude palm oil (CPO) on injection system, performance and emission of a diesel engine

Crude palm oil (CPO) is one of the vegetable oils that have potential for use as fuels for diesel engines. CPO is renewable, and is safe and easy to handle. However, at room temperature (30–32°C) CPO has a viscosity about 10 times higher than that of diesel. To lower CPO’s viscosity to the level of diesel’s viscosity, a heating temperature of at least 92 °C is needed. At this temperature, there is a concern that the close-fitting parts of the injection system might be affected. This study focused on finding out the effects of preheating of fuel on the injection system utilising a modified method of friction test, which involves injecting fuel outside the combustion chamber during motoring. Results show that preheating of CPO lowered CPO’s viscosity and provided smooth fuel flow, but did not affect the injection system, even heating up to 100 °C. Nevertheless, heating up to such a high temperature offered no benefits in terms of engine performance. However, heating is necessary for smooth flow and to avoid fuel filter clogging. Both can be achieved by heating CPO to 60 °C. Combustion analyses comparisons between CPO and diesel found that CPO produced a higher peak pressure of 6%, a shorter ignition delay of 2.6°, a lower maximum heat release rate and a longer combustion period. Over the entire load range, CPO combustion produced average CO and NO emissions that were 9.2 and 29.3% higher, respectively, compared with those from diesel combustion.     

Performance analysis of a mono-cylinder diesel engine using soy straight vegetable oil as fuel with varying temperature and injection angle

Experimental results are presented for a compression ignition engine with one cylinder refrigerated by air, fueled with soy straight vegetable oil (SVO), filtered at 500 nm and blended with diesel at volume percentages of 10, 30, 50, 70 and 100%. Performance tests varying the injection angle and the fuel temperature were conducted. The results show an increase in torque and power compared to pure diesel, especially with the SVO50 and SVO70 mixtures. However, there was an increase in the specific consumption, although engine efficiency was only slightly lower due to the lower heating value of oil. The use of SVO as fuel is feasible, but durability tests must be performed, mainly to discover potential maintenance problems.     

Impacts of additives on performance and emission characteristics of diesel engines during steady state operation

Depletion of fossil fuel resources and stringent emission mandates has spurred the search for improved diesel engines performance and cleaner combustion. One of the best approaches to solve these issues is to use biodiesel/diesel additives. The effects of biodiesel/diesel additives on the performance and emissions of diesel engines were comprehensively reviewed throughout this article. The additives reviewed herein were classified into five categories, i.e., oxygenated additives, metallic and non-metallic based additives, water, antioxidants, and polymeric-based additives. The effects of each category on the engine performance (i.e., brake specific fuel consumption (bsfc) and brake thermal efficiency (bte)) and emissions (i.e., CO, NO_x, HC, and PM) were exclusively summarized and discussed. Furthermore, various strategies used for adding water like water-diesel emulsion, direct water injection, and adding water into the inlet manifold were illustrated and their pros and cons were completely scrutinized. Finally, opportunities and limitations of each additive considering both engine performance and combustion benignity were outlined to guide future research and development in the domain.     

Combustion characteristics and emissions of Fischer-Tropsch diesel fuels in IC engines

This article gives a condensed overview of Gas-to-Liquid (GTL), Biomass-to-Liquid (BTL) and Coal-to-Liquid (CTL) theory and technology by the use of Fischer-Tropsch (F-T) processes. Variations of the F-T process can be used to tailor the fuel properties to meet end user needs as well as aid vehicle manufacturers in achieving forthcoming emission regulations. They do this by improving engine-out emissions and exhaust gas after-treatment performance. Regardless of feedstock or process, F-T diesel fuels typically have a number of very desirable properties, including a very high cetane number. This review focuses on how fuel properties impact pollutant emissions and draws together data from various studies that have been carried out over the past few years. Reduced emission levels as demonstrated in several publications have been attributed to several chemical and physical characteristics of the F-T diesel fuels including reduced density, ultra-low sulfur levels, low aromatic content and high cetane rating, but not all of them contribute to the same extent to the emissions reduction.