Cetane Number Improver Research Articles

Effects of the addition of ethanol and cetane number improver on the combustion and emission characteristics of a compression ignition engine

Combustion and emission characteristics of a direct-injection diesel engine fuelled with diesel—ethanol blends were investigated. The results show that the ignition delay and the premixed combustion duration increase, while the diffusive combustion duration and the total combustion duration decrease with increase in the oxygen mass fraction in the blends. The addition of 0.2 per cent volume fraction of cetane number improver (isoamyl nitrite) could mean that the ignition delay and the premixed combustion duration of the fuel blends with 10vol% ethanol fraction recover to those of diesel fuel. Meanwhile, with the increase in the ethanol fraction in the fuel blends, the centre of the heat release curve moves closer to the top dead centre. The brake specific fuel consumption increases, while the diesel equivalent brake specific fuel consumption decreases with increase in the ethanol fraction. The exhaust smoke concentration increases and exhaust nitrogen oxide (NO x) concentration decreases on prolonging the fuel delivery advance angle for both diesel fuel and the blended fuels. For a specific fuel injection advance angle, the exhaust smoke concentration shows a large decrease and the exhaust NO x concentration a small decrease on ethanol addition.

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.

Combustion characteristics of a compression ignition engine fuelled with diesel—ethanol blends

Combustion characteristics were analysed in a compression ignition engine fuelled with diesel—ethanol blends with and without a cetane number improver. The results show that, for the same brake mean effective pressure and engine speed, the maximum cylinder pressure Pmax, the ignition delay, the premixed combustion duration, and the fraction of heat release in premixed combustion phase will increase, while the diffusive combustion duration, the fraction of diffusive combustion phase, and the total combustion duration decrease with increase in the ethanol fraction in the blends. Meanwhile, the centre of the heat release curve moves close to the top dead centre, and the maximum rate (d Qb/d φ)max of heat release and the maximum rate (d p/d φ)max of pressure rise increase with increase in the ethanol fraction in the blends. The addition of a cetane number improver is beneficial to the decrease in the ignition delay, the cylinder peak pressure, the maximum rate of pressure rise, and the combustion noise when operating on diesel—ethanol blends.

Comparative study of the hydrogenation of tetralin on supported Ni, Pt, and Pd catalysts

The hydrogenation of tetralin in the vapor phase has been investigated over Ni, Pt, and Pd catalysts to determine the evolution of the trans- and cis-decalin products as a function of conversion over the different catalysts. The concentration of each isomer in the product may be important in subsequent ring opening steps if cetane number improvement is desired. The cis-decalin isomer is preferred to open the naphthenic ring in a selective way instead of multiple cracking. However, thermodynamically, this isomer is the least favored; so, kinetic control is the only solution. By selecting the proper catalyst and operating conditions, one could keep the trans/cis-decalin ratio low. In this study, we have prepared a series of supported metal catalysts and tested them in a flow reactor at 3540kPa and 548K. Kinetic parameters for the hydrogenation of tetralin and the cis-to-trans-decalin isomerization over the various catalysts investigated were obtained by fitting the data with a generalized Langmuir–Hinshelwood model.The kinetic analysis revealed that the relative rates of tetralin hydrogenation, as well as the cis-to-trans isomerization are greatly affected by adsorption site competition of decalin and tetralin, which in turn has different magnitudes over the different catalysts. At tetralin conversions above 30%, the Ni catalyst yields the lowest trans/cis-decalin ratio. In contrast, the trans/cis ratio on Pd catalyst remains constant at all conversion levels and is highest at low tetralin conversion. It is concluded that the trans/cis ratio is a combination of the intrinsic selectivity of each isomer and the isomerization reaction.

Evaluation of different reaction strategies for the improvement of cetane number in diesel fuels

Cetane number improvement of diesel fuels is a difficult task that refiners will face in the near future. Aromatics saturation by deep hydrogenation is a necessary, but perhaps not sufficient step in the diesel treatment. Some researchers have proposed selective ring opening (SRO) as an additional step in the upgrading. In this work, we explore some possible reaction pathways of compounds typically found in diesel after different levels of hydrogenation, i.e. decalin (decahydronaphthalene), perhydrophenanthrene, tetralin (1,2,3,4-tetrahydronapthalene), as well as 1-ring and 2-ring aromatic phenanthrenes. We have estimated the cetane number (CN) of each individual compound involved in the reaction pathways, using an artificial neural network program that was trained with pure compound cetane numbers from a database. The results demonstrate the great challenge that reaching high CN represents. In the conversion of decalin, acidic catalysts alone are not able to yield products with CN significantly higher than the decalin feed. Similarly, no significant gain in CN can be expected with hydrogenolysis metal catalysts operating via the dicarbene mechanism. Only in the case of selective metal-catalyzed hydrogenolysis, with preferential cleavage at substituted C–C bonds, the predicted products have CN substantially higher than the decalin feed. As expected, branching has a strongly negative effect on the CN and it should be minimized. Both, metal-catalyzed di-carbenium C–C cleavage and acid-catalyzed ring contraction/ring opening combination leave branching groups in the product. Similarly, the acid-catalyzed ring opening of perhydrophenanthrene does not result in a significantly higher CN than the initial feed. The possibility of minimizing hydrogen consumption in the CN improvement process by an initial partial hydrogenation followed by ring opening was tested by using phenanthrene and tetralin as probe molecules. In the first reaction strategy, partially hydrogenated phenanthrenes (1-ring and 2-ring aromatics) were followed by ring opening of one of the saturated rings. Although this option would lead to lower overall hydrogen consumption, it results in products of much lower CNs than the ones obtained by full hydrogenation of phenanthrene. Similar results are obtained for tetralin. From this analysis, it is clear that upgrading CN of diesel requires extensive hydrogen consumption. For further upgrading, highly selective hydrogenolysis catalysts are needed in order to minimize branching and therefore obtain high CN products.

Improving the Combustion and Emissions of Direct Injection Compression Ignition Engines Using Oxygenated Fuel Additives Combined with a Cetane Number Improver

According to the fuel design concept, three oxygenated fuels including ethanol, dimethyl carbonate (DMC), and dimethoxy methane (DMM) were selected to mix with diesel fuel. Then, the effects of oxygen content and the cetane number of the blend fuels on diesel engine combustion and emissions were evaluated. The experiments were conducted on a four-cylinder high-speed diesel engine. The results show that, with the increase of the oxygen content in blend fuels, the ignition timing delays and the combustion duration shorten at different operating conditions, and the brake thermal efficiency improves from middle to full loads. The engine NOx emissions decreased at overall operating ranges when oxygenated fuels were added to the diesel fuel, and smoke emissions also improved for all oxygenated blend fuels except for ethanol−diesel blends at low and middle loads. In the case of the DMC−diesel blend fuel, when the oxygen content increased up to 15%, the smoke number decreased by 75%, and NOx emission improved by ...

THE INFLUENCE OF ETHANOL ADDITIVES ON THE PERFORMANCE AND COMBUSTION CHARACTERISTICS OF DIESEL ENGINES

The purpose of this paper is to experimentally investigate the engine pollutant emissions and combustion characteristics of a diesel engine fueled with ethanol/diesel blended fuel. The experiments were performed using various proportions of ethanol/diesel blended fuels in a single-cylinder direct injection (DI) diesel engine. The engine performance parameters and emissions were measured and compared to those using the baseline diesel fuel. To gain insight into the combustion characteristics of ethanol/diesel blends, the engine combustion processes for blended fuels and diesel fuel were observed using an engine video system (AVL 513). The results show that the brake specific fuel consumption increased at overall engine operating conditions, but it is worth noting that the brake thermal efficiency increased by up to 1–2.3% with 10 and 15% ethanol/diesel blended fuels. It is found that engines fueled with ethanol/diesel blended fuels have higher emissions of total hydrocarbon (THC), and lower emissions of CO, NOx, and smoke. The results also indicate that the cetane number improver has a positive effect on CO and NOx emissions, but a negative effect on THC emission. Based on the engine combustion visualization and in-cylinder temperature field analysis by using the primary color method, it is found that the ignition delay increased, the total combustion duration and the luminosity of the flame decreased, and the peak combustion temperature decreased for ethanol/diesel blended fuels.

Effect of cetane number improver on heat release rate and emissions of high speed diesel engine fueled with ethanol–diesel blend fuel

This article investigates the influence of cetane number improver on heat release rate and emissions of a high-speed diesel engine fueled with ethanol–diesel blend fuel. Different percentages of cetane number enhancer (0, 0.2, 0.4%) were added to blends, and the engine tests were performed on a 4-cylinder high-speed DI diesel engine. The results show that: the brake specific fuel consumption (BSFC) increased, the diesel equivalent BSFC decreased, the thermal efficiency improved remarkably, and NOx and smoke emissions decreased simultaneously when diesel engine fueled with ethanol–diesel blend fuels; NOx and smoke emissions further reduced when CN improver was added to blends. From the combustion analysis, it can be found that the ignition delay prolonged, and the total combustion duration shortened for ethanol–diesel blend fuels when compared to diesel fuel; the combustion characteristics of ethanol–diesel blend fuel at large load may be resumed to diesel fuel by CN improver, but a large difference exists at lower load yet.

04/00071 Effects of molecular structures of alkanes on peroxide formation and cetane number improvement by autoxidation: Hashimoto, K. et al. Journal of the Japan Petroleum Institute, 2003, 46, (2), 142–147

04/00071 Effects of molecular structures of alkanes on peroxide formation and cetane number improvement by autoxidation: Hashimoto, K. et al. Journal of the Japan Petroleum Institute, 2003, 46, (2), 142–147

03/01899 Condition of internal-combustion engine fuels by passage of nitrogen oxides from exhaust gas for in-situ formation of ignition enhancers and cetane number improvers: Degen, W. et al. U.S. Pat. Appl. Publ. US 2002 144,456 (Cl. 44–1112; C10L1/22), 10 Oct 2002, Appl. 10,107,616

03/01899 Condition of internal-combustion engine fuels by passage of nitrogen oxides from exhaust gas for in-situ formation of ignition enhancers and cetane number improvers: Degen, W. et al. U.S. Pat. Appl. Publ. US 2002 144,456 (Cl. 44–1112; C10L1/22), 10 Oct 2002, Appl. 10,107,616

Improving the Cetane Number of Diesel Fuels

Effect of paraffins C10-C13, C14-C17, C18-C23, tert-butyl hydroperoxide, cumyl hydroperoxide, and isopropyl nitrate as cetane number improvers for summer- and winter-grade diesel fuels, added in amount of 0.4-5 wt %, is studied.

Effects of Molecular Structures of Alkanes on Peroxide Formation and Cetane Number Improvement by Autoxidation

Diesel fuels having poor ignition properties would induce problems such as diesel knock and engine starting problems in cold weather. Diesel fuels in such cases need to have improved ignition properties. The addition of cetane number improving agents to diesel fuels is one method to improve the ignition properties of diesel fuels. However, addition of cetane number improving agents is not always an economically practical solution to improve the ignition properties of diesel fuels. Our previous study showed that the cetane numbers of autoxidized fuels in which hydroperoxides were produced increased. It is important for the development of cetane number improving systems by autoxidation to investigate the effects of molecular structures of hydrocarbons on the formation of hydroperoxides and the cetane number improvement. In this study, effects of carbon numbers and branching of alkanes on the formation of hydroperoxides were investigated. As a result, smaller carbon numbers produced more hydroperoxides. Also, effects of the molecular structures of the hydrocarbons on cetane ' number improvement by produced hydroperoxides have been investigated. The result suggests that the hydroperoxide produced from alkanes having a lower carbon number increases cetane number more. Furthermore, polynuclear aromatic hydrocarbons such as naphthalene and 1-methyl naphthalene had inhibition effects on the hydroperoxide production by autoxidation. From above results, the autoxidation could be a good method for improving diesel fuels such as city diesel and kerosene having low aromatic compounds and low distillation ranges because these fuels have to add cetane number improving agents to increase its number.

An analysis for effect of cetane number on exhaust emissions from engine with the neural network

Decoupling cetane number from the other compositions and properties of diesel fuel, the individual effect of cetane number on the exhaust emissions from an engine may be researched. This paper has presented a back-propagation neural network model predicting the exhaust emissions from an engine with the inputs of total cetane number, base cetane number and cetane improver, total cetane number and nitrogen content in the diesel fuel; as well as the output of the exhaust emissions of hydrocarbon (HC), carbon oxide (CO), particulate matter (PM) and nitrogen oxide (NO x ). An optimal design has been completed for the number of hidden layers, the number of hidden neurons, the activation function, and the goal errors, along with the initial weights and biases in the back-propagation neural network model. HC, CO, PM and NO x have been predicted with the model, the effects of cetane improver and nitrogen content on them have also been analyzed, and better results have been achieved.

Alaska North Slope crude oil price and the behavior of diesel prices in California

This paper first of all summarized the auto-ignition mechanism of high cetane and high octane number fuels from the aspect of chemical reaction kinetics with the main purpose of explaining different auto-ignition characteristics of the two kinds of fuel and providing a classification of fuels with the same ignition principles. High cetane number fuels cover major real compression-ignition internal combustion engine fuels and references fuels in use, including straight-chain alkanes, straight-chain ethers, straight-chain esters and cetane number improvers while high octane number fuels cover major real spark-ignition internal combustion engine fuels and references fuels in use, including hydrogen, carbon monoxide, small molecular alkanes, small molecular ethanol, branched alkanes, cycloalkanes, light olefins, simple aromatic hydrocarbons and gasoline antiknock branched ethers. On this basis, 8 representative high octane number fuels were selected for mixing with the high cetane number fuel n-heptane to study the ignition characteristics of mixed fuels in order to find mechanism and corresponding rules.

A study of ignition delay of diesel fuel sprays

Diesel fuel ignition delay times were characterized in a rapid compression machine (RCM) using cylinder ambient gas temperature and pressure measurements as diagnostics. The objective of the study was to investigate the dependency of ignition delay time on: (a) cylinder ambient gas temperature, (b) cylinder ambient gas pressure, (c) injection pressure, (d) injector nozzle orifice diameter, (e) base fuel cetane number and (f) 2-ethylhexyl nitrate (2-EHN) cetane improver additive. The results presented here show that diesel ignition delay times can be shortened by increasing cylinder gas ambient temperatures and pressures, injection pressures and base fuel cetane number, either through blend components or by addition of cetane improver. Decreasing the injector nozzle orifice diameter also decreases the ignition delay time. It was also found that ignition chemistry is rate controlled by the molar concentration of the cylinder gas oxygen.

97/00802 Cetane number improvement of diesel fuel by autoxidation

97/00802 Cetane number improvement of diesel fuel by autoxidation

Cetane Number Improvement of Diesel Fuel by Autoxidation

Diesel fuels having low cetane numbers may have ignition problems such as diesel knock, difficult engine starts in cold weather, and need for addition of cetane number improving agents. As organic peroxides are known to be effective cetane number improving additives, hydroperoxides produced in the autoxidation of hydrocarbons can be expected to improve cetane number. In this study, the cetane numbers of diesel fuels autoxidized in the liquid phase under various conditions have been examined. As a result, autoxidized diesel fuels have been found to have higher cetane numbers. Hydroperoxides are also found to be produced in the autoxidation of diesel fuels. It is suggested that hydroperoxides produced from diesel fuel autoxidation should have an important role in increasing its cetane number.

発火温度によるディーゼル燃料の着火性評価

In order to obtain some information on ignition property of diesel fuels, we have attempted to determine autoignition temperatures of various diesel fuels and to compare those with their cetane numbers. As a result it was shown that the autoignition temperature of the diesel fuels should have a tendency to decrease with an increase in their cetane number and that the addition of the cetane number improving agents could make autoignition temperatures lower. We suggest that the autoignition temperature test should be useful screening one to evaluate the cetane number and the cetane number improvement of diesel fuels.

ディーゼル燃料のセタン価向上効果に関する研究

The effects of alkyl nitrates, alkyl nitrites and organic peroxides on cetane number were investigated to provide the mechanism of the improvement of cetane number improvers. It was found that all the alkyl nitrates, alkyl nitrites and organic peroxides improved cetane number of diesel fuel. In the thermolysis of cetane number improvers, free radicals were formed. Aldehydes, ketones, nitric oxides and nitric diox-ides produced were not concerned with the increment of cetane number. We consider that free radicals have influences on cetane number improvement. The n-alkyl nitrite containing more carbon atoms makes higher improvement on cetane number. The alkyl radicals containing more carbon atoms make higher increment on cetane number.

Application of 13C and 1H nuclear magnetic resonance for the evaluation of cetane rating of middle distillates

Proton and 13C nuclear magnetic resonance studies have shown that no direct relationship exists between cetane rating and contributions of the various structural groups to cetane index. Therefore, this empirical method can be recommended for research purposes only, and only in those cases where the sample is derived from the same streams on which the calculation was based. Since nuclear magnetic resonance cannot reveal the presence of cetane improvers in unknown samples, a new method for determining cetane number improvers, using negative-ion, chemical-ionization mass spectrometry, has been introduced for checking for the presence of such materials in comparative evaluation of cetane engine test and NMR data.