Search Results (40)

Diesel engines are extensively employed in transportation, agriculture, and industry due to their high thermal efficiency and fuel economy. However, the combustion of conventional diesel fuel is accompanied by substantial emissions of pollutants, including carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO_x), and carbon dioxide (CO₂), posing significant threats to environmental quality. Biodiesel, as a renewable and cleaner alternative fuel, can significantly reduce emissions of CO, HC, and particulate matter (PM) due to its unique molecular structure. Nonetheless, its lower calorific value and poor cold-start performance limit its application, while its high oxygen content may contribute to increased NO_x emissions. To address these limitations, researchers have proposed blending biodiesel with alcohol-based fuels such as methanol, ethanol, or butanol to create synergistic combustion systems that optimize engine performance and emission characteristics. This paper systematically reviews the effects of alcohol fuels on the performance and emission characteristics of biodiesel blends in diesel engines. Studies indicate that the addition of alcohol fuels can significantly enhance engine performance by improving fuel atomization, extending ignition delay, and increasing premixed combustion efficiency. These enhancements result in higher cylinder pressure, net heat release rate (HRR), and brake thermal efficiency (BTE), while reducing brake-specific fuel consumption (BSFC) to some extent. Moreover, most studies report that alcohol fuels help reduce CO, HC, smoke, and NO_x emissions but tend to increase CO₂ emissions. However, some findings suggest that in certain cases, the opposite results may occur. The impact of different types of alcohol fuels on performance and emissions varies significantly, requiring a comprehensive evaluation of their properties, such as latent heat, viscosity, and oxygen content. Although the appropriate addition of alcohol fuels demonstrates substantial potential for optimizing engine performance and reducing emissions, excessive blending may lead to adverse effects, necessitating careful control of the blending ratio. Future research should consider mixing two or more alcohol fuels with biodiesel to explore synergistic effects beyond the capabilities of single alcohols. Additionally, further studies should focus on optimizing fuel compositions and emission control strategies for varying operating conditions. Full article

This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the focus was placed on investigating the specific impacts of ethanol and n-butanol additives on diesel engine performance. Research shows that a fuel mixture consisting of 70% diesel, 10% biodiesel, and 20% ethanol reduced NOx emissions by 5.56% compared to pure diesel at 75% load. Furthermore, this study explores the combustion performance of diesel/biodiesel blended with butanol/ethanol. The findings indicate that n-butanol improves thermal efficiency, particularly at 100% load, with the D70B10E20 and D70B10BU20 blends demonstrating thermal efficiencies of 9.94%and 8.72% higher than that of diesel alone, respectively. All mixed fuels exhibited reduced hydrocarbon and CO emissions under different loads, with a notable reduction in hydrocarbon emissions of 34.4% to 46.1% at 75% load. Full article

In the era of decarbonization driven by environmental concerns and stimulated by legislative measures such as Fit for 55, the industry and transportation sectors are increasingly replacing petroleum-based fuels with those derived from renewable sources. For many years, the share of these fuels in blends used to power compression ignition engines has been growing. The primary advantage of this fuel technology is the reduction of GHG emissions while maintaining comparable engine performance. However, these fuel blends also have drawbacks, including limited ability to form stable mixtures or the requirement for chemical stabilizers. The stability of these mixtures varies depending on the type of alcohol used, which limits the applicability of such fuels. This study focuses on evaluating the impact of eight types of alcohol fuels, including short-chain (methanol, ethanol, propanol) and long-chain alcohols (butanol, pentanol, hexanol, heptanol, and octanol), on the most critical operational parameters of an industrial engine and exhaust emissions. The engines being compared operated at a constant speed and under a constant load, either maximum or close to maximum. The study also evaluated the effect of alcohol content in the mixture on combustion process parameters such as peak cylinder pressure and heat release, which are the basis for parameterizing the engine’s combustion process. Determining ignition delay and combustion duration is fundamental for optimizing the engine’s thermal cycle. As the research results show, both the type of alcohol and its concentration in the mixture influence these parameters. Another parameter important from a usability perspective is engine stability, which was also considered. Engine performance evaluation also includes assessing emissions, particularly the impact of alcohol content on NO_x and soot emissions. Based on the analysis, it can be concluded that adding alcohol fuel to diesel in a CI engine increases ignition delay (up to 57%), p_max (by approximately 15–20%), HRR_max (by approximately 80%), and PPR_max (by approximately 70%). Most studies indicate a reduction in combustion duration with increasing alcohol content (by up to 50%). For simple alcohols, an increase in thermal efficiency (by approximately 15%) was observed, whereas for complex alcohols, a decrease (by approximately 10%) was noted. The addition of alcohol to diesel slightly worsens the stability of the CI engine. Most studies pointed to the positive impact of adding alcohol fuel to diesel on NOx emissions from the compression ignition engine, with the most significant reductions reaching approximately 50%. Increasing the alcohol fuel content in the diesel blend significantly reduced soot emissions from the CI engine (by up to approximately 90%). Full article

One promising oxygenate additive being considered as a fuel component for diesel engines is 1-butanol. However, since 1-butanol is characterized, like many other alcohols, by poor autoignition properties and, consequently, a low cetane number, the introduction of this additive into diesel fuel naturally worsens the autoignition properties of the blend so obtained. It is usual to consider a proportion of 1-butanol no higher than approx. 30% alcohol by volume. Thus, when considering the addition of 1-butanol to diesel fuel, it is necessary to improve the autoignition properties of such a blend. One such additive may be 2-ethylhexyl nitrate (2-EHN). This article determines the effect of the 2-EHN additive on the autoignition properties of a blend of 1-butanol and diesel fuel at an alcohol content of 30% (v/v). The tests were carried out using a constant volume combustion chamber method, which additionally made it possible to determine the effect of ambient gas temperature on the ignition delay (ID), combustion delay (CD) and derived cetane number (DCN), among other factors. The study showed, among other things, that with an increase in the mass proportion of 2-EHN in the 1-butanol–diesel blend (BDB) tested, the ignition and combustion delay were shortened, which resulted in an increase in the value of the derived cetane number. Full article

In recent years, biofuels have gained considerable prominence in response to growing concerns about resource scarcity and environmental pollution. Previous investigations have revealed that the appropriate blending of iso-propanol–butanol–ethanol (IBE) into diesel significantly improves both the c combustion efficiency and emission performance of internal combustion engines (ICEs). However, the combustion mechanism of IBE–diesel for the numerical studies of engines has not reached maturity. In this study, a skeletal IBE–diesel multi-component mechanism, comprising 157 species and 603 reactions, was constructed using the decoupling method. It was formulated by amalgamating the reduced fuel-related sub-mechanisms derived from diesel surrogates (n-dodecane, iso-cetane, iso-octane, toluene, and decalin) and n-butanol, along with the detailed core sub-mechanisms of C₁, C₂, C₃, CO, and H₂. The constructed mechanism is capable of better matching the physical and chemical properties of actual diesel fuel. Extensive validation, including ignition delay, laminar flame speed, a premixed flame species profile, and engine experimental data, confirms the reliability of the mechanism in engine numerical studies. Subsequent investigations reveal that as the IBE blend ratio and EGR rate increase, the ignition delay exhibits an increase, while the combustion duration experiences a decrease. Blending IBE into diesel, along with a specific EGR rate, proves effective in simultaneously reducing NOx and soot emissions. Full article

Fossil fuel extraction and utilization are associated with several environmental issues. This study examined how altering the blending proportions of mixed diesel/biodiesel/n-butanol fuels impacts combustion. Additionally, it delved into the functioning of diesel engines when utilizing these blended fuels as well as conventional diesel. A three-dimensional fluid dynamics simulation was constructed and corroborated against test outcomes obtained at 25%, 50%, 75%, and 100% loads. The findings indicated that the n-butanol addition enhanced the indicated thermal efficiency. At a 100% load, D70B30 (70% diesel + 30% biodiesel), D70B25BU5 (70% diesel + 25% biodiesel + 5%N-butanol), D70B20BU10, and D70B10BU20 exhibited 4.76%, 5.75%, 6.79%, and 8.71% higher indicated thermal efficiency values than D100 (100% diesel), respectively. The introduction of butanol enhanced the combustion environment within the combustion chamber. Compared with pure diesel, all blended fuels reduced hydrocarbon and carbon monoxide emissions across various loads. The blended fuels showed significant reductions in hydrocarbon emissions of 1%, 4%, 6%, and 15% compared with that of diesel under the 25% load, respectively. Full article

Aiming to achieve the goal of efficient and clean combustion in internal combustion engines, simulations are used to change the physicochemical properties and molecular configuration of fuels by adding oxygenated fuels such as alcohols, esters, ethers, etc., so as to achieve the purpose of improving combustion and reducing emissions. In this paper, blends of oxygenated fuels, including n-butanol, DME, DMC, and diesel fuel with different oxygen-containing functional groups, were selected for simulation to reveal the chemical mechanisms of fuel oxygen on combustion and pollutant generation in the combustion system and to deeply explore the mechanism and influence law of the different forms of oxygen bonding on the generation and oxidation of carbon smoke. At the same fuel oxygen content, the differences in the fuel physicochemical properties and reaction paths resulted in different effects of the different oxygenated fuels on the in-cylinder oxidative activity and different inhibition abilities of carbon smoke precursors. Compared with pure diesel, n-butanol, and DME, which promoted OH generation, DMC inhibited OH generation, so the oxidation activity of diesel/n-butanol was the highest, and that of diesel/DMC was the lowest; meanwhile, the two O atoms in the DMC molecule formed CO₂ with one C atom, which reduced the utilization efficiency of the O atoms, whereas each O atom in the n-butanol and DME fuels took away one C atom, so the utilization efficiency of O atoms was higher. The individual oxygenated fuels themselves had different abilities to contribute to carbon smoke precursors, and the above combined factors led to reductions of 8.7%, 32.6%, and 85.4% in soot emissions from the addition of DMC, DME, and n-butanol compared to pure diesel fuel, respectively, at the same oxygen content. At a medium load, the addition of n-butanol, DME, and DMC reduced NOx emissions by 0.5%, 1.7%, and 3.3%, respectively. Thus, it is shown that DMC has a more significant effect on NOx emission reduction. Full article

Isobutanol, one of the four isomers of butanol (C₄H₉OH), possesses some favorable properties that make it an attractive fuel for internal combustion engines. For instance, when compared to ethanol, isobutanol features a higher heating value and lower hygroscopicity (which prevents corrosion and enables it to be transported via pipelines). Moreover, its addition to gasoline does not distort the fuel blend’s vapor pressure to the same extent as ethanol does. All of this while having a high octane rating. Those advantages over ethanol suggest that isobutanol has the potential to be used as a gasoline oxygenate or even as a neat fuel. Furthermore, the advances made in biotechnology have enabled isobutanol to be produced from biomass more efficiently, allowing it to be used in compliance with existing renewable energy mandates. This article reviews some of the relevant literature dedicated to isobutanol as a motor fuel, covering its merits and drawbacks. Several studies on its combustion characteristics are also discussed. Most of the included literature refers to the use of isobutanol in spark-ignition (SI) engines, as its properties naturally lend themselves to such applications. However, isobutanol’s utilization in diesel engines is also addressed, along with a couple of low-temperature combustion examples. Full article

This paper reports density, kinematic viscosity, and distillation curves for blends of diesel fuel with n-butanol, diesel fuel with n-pentanol, and diesel fuel with diethylene glycol dimethyl ether. It is known that these properties affect not only fuel transportation and distribution processes but also the phenomena that occur in an internal combustion engine; therefore, these aspects are intriguing to study. Oxygenated compounds such as n-butanol, n-pentanol, and diethylene glycol dimethyl ether can be used as additives for diesel fuel. Their use can contribute to a significant improvement in the fuel’s ignitability due to their high oxygen contents. Measurements of the experimental properties of various blend compositions were carried out at temperatures ranging between 288.15 K and 323.15 K. Based on density and viscosity data, different mathematical models were verified for the purpose of establishing better quality standards for the production of fuel. Good accuracies were obtained in the cases of density, viscosity, and interaction parameters, with the largest average absolute deviation (AAD%) being 0.4351. Moreover, as the determination of density is uncomplicated, rapid, and requires small sample volumes, correlations with the distillation temperatures used for the fuel blends were investigated to estimate the samples’ cetane indices. These determinations will be useful in the automobile industry when designing transport equipment or pipelines in situations when oxygenated compounds may constitute a fuel component in diesel blends. Full article

Biofuels are environmental friendly renewable fuels, that can be directly used in a diesel engine. However, a few shortcomings like a higher density, viscosity, a lower calorific value and increase in NOx emissions, has caused researchers to look for fuel additives to improve the physiochemical properties of these fuels and to enhance their performance and reduce harmful emissions. It is for this reason that modern research is focused on blending oxygenated additives such as alcohols and ethers with different generations of biodiesel. Since most studies have covered the effect of alcohol on biodiesel, there are few studies which have investigated the effect of oxygenated additives such as alcohols and ethers, especially related to second-generation biodiesel. Moreover, the details of their composition and molecular structure are still lacking. Hence, this study focuses on the performance and emission characteristics of biodiesel with the inclusion of oxygenated additives (alcohols and ethers) of non-edible-oil-based second-generation blends. The reviewed results showed that Neem biodiesel with methanol or diethyl ether reduced brake-specific fuel consumption by 10%, increased brake thermal efficiency by 25% and reduced CO and HC emissions due to a higher oxygen content. Diethyl ether reduced NOx emissions as well by producing a cooling effect, i.e., a reduced in-cylinder temperature. The addition of heptane, butanol and di ethyl ether to Jatropha biodiesel showed an improved brake thermal efficiency and an increment in brake-specific fuel consumption (5–20%), with reduced HC and CO₂ (3–12%) emissions. Calophyllum inophyllum biodiesel also showed impressive results in terms of improving efficiency and reducing emissions with addition of butanol, pentanol, decanol and hexanol. Other factors that influenced emissions are the cetane number, viscosity, density and the latent heat of evaporation of tested biodiesel blends. This review would help the research community and the relevant industries to consider an efficient biodiesel blend for future study or its implementation as an alternate fuel in diesel engines. Full article

In recent years, the interest in renewable fuels has increased mainly due to regulations regulating the permissible limits of toxic components of exhaust gases emitted by reciprocating engines. This paper presents the results of a comparison of the effects of fueling a compression-ignition piston engine with a mixture of diesel fuel and n-butanol, as well as RME (Rapeseed Oil Methyl Esters) biodiesel and n-butanol. The tests were carried out for a constant load and a wide energetic share of fuels in the mixture. The main focus was on the assessment of combustion stability, the uniqueness of the combustion stages, and the assessment of the fuel type influence on the CA50 angle. The tests show that RME offers the possibility of efficient combustion with n-butanol with up to 80% energy share. The share of n-butanol has a positive effect on the engine’s efficiency and very effectively reduces soot emissions. Without the influence on COV_IMEP, the share of n-butanol up to 40% in the mixture with diesel fuel and up to 80% in the mixture with RME was recorded. Combustion of RME with n-butanol was more stable. The share of n-butanol in the mixture with diesel fuel caused an increase in NO_x emissions, and co-combustion with RME caused a decrease in emissions. Full article

The current study aims to investigate and compare the effects of waste plastic oil blended with n-butanol on the characteristics of diesel engines and exhaust gas emissions. Waste plastic oil produced by the pyrolysis process was blended with n-butanol at 5%, 10%, and 15% by volume. Experiments were conducted on a four-stroke, four-cylinder, water-cooled, direct injection diesel engine with a variation of five engine loads, while the engine’s speed was fixed at 2500 rpm. The experimental results showed that the main hydrocarbons present in WPO were within the range of diesel fuel (C13–C18, approximately 74.39%), while its specific gravity and flash point were out of the limit prescribed by the diesel fuel specification. The addition of n-butanol to WPO was found to reduce the engine’s thermal efficiency and increase HC and CO emissions, especially when the engine operated at low-load conditions. In order to find the suitable ratio of n-butanol blends when the engine operated at the tested engine load, the optimization process was carried out by considering the engine’s load and ratio of the n-butanol blend as input factors and the engine’s performance and emissions as output factors. It was found that the multi-objective function produced by the general regression neural network (GRNN) can be modeled as the multi-objective function with high predictive performances. The coefficient of determination (R²), mean absolute percentage error (MAPE), and root mean square error (RSME) of the optimization model proposed in the study were 0.999, 2.606%, and 0.663, respectively, when brake thermal efficiency was considered, while nitrogen oxide values were 0.998, 6.915%, and 0.600, respectively. As for the results of the optimization using NSGA-II, a single optimum value may not be attained as with the other methods, but the optimization’s boundary was obtained, which was established by making a trade-off between brake thermal efficiency and nitrogen oxide emissions. According to the Pareto frontier, the engine load and ratio of the n-butanol blend that caused the trade-off between maximum brake thermal efficiency and minimum nitrogen oxides are within the approximate range of 37 N.m to 104 N.m and 9% to 14%, respectively. Full article

This paper investigates impact of magnetite dispersed in butanol and added to two varied blends of palm biodiesel and diesel (B20 and B30). The developed fuel samples were characterized and tested on single cylinder diesel Yanmar engine (L70N) to observe engine behavior for emissions and performance. Results are compared with two reference fuels: YF50 fuel contains 50 ppm magnetite in B20 and B_n10Y90 contains 10% butanol with 90% B20. Addition of magnetite and butanol depletes emissions levels and improve performance compared to ordinary B20 and B30 however; samples with higher dosage of magnetite (150 ppm) yielded better results in performance and emission compared with lower dosage (75 ppm). The best sample was C10Z90 which entails 150 ppm magnetite in butanol added at 10% to B30. Brake thermal efficiency (BTE) at highest brake power (BP) point for C10Z90 was 37.28% compared to others (32.88%, 35.22% and 35.96%). Additionally, brake specific fuel consumption (BSFC) of C10Z90 was at least 8.29 g/Kw.hr and at most 84.52 g/Kw.hr less than other samples at highest BP point. Results indicated C10Z90 was lower in carbon-monoxide, hydrocarbon and smoke except for oxides of nitrogen. Artificial Neural Network (ANN) model successfully predicted BTE, BSFC and emissions of the dual fuel application. Full article

In recent decades, many kinds of research have been conducted on alternative fuels for compression ignition (CI) engines. Low/zero-carbon fuels, such as bioalcohols and hydrogen, are the most promising alternative fuels and are extensively studied because of their availability, ease of manufacturing, and environmental benefits. Using these promising fuels in CI engines is environmentally and economically beneficial. The most common alcohols are methanol, ethanol, isopropanol, propanol, butanol, n-butanol, tert-butanol, iso-butanol, and pentanol. The primary objective of this review paper is to examine the impact of bioalcohols and their blends with conventional diesel fuel in CI engines since these fuels possess characteristic properties that impact overall engine performance and exhaust emissions. This research also indicated that alcohols and blended fuels could be used as fuels in compression ignition engines. Chemical and physical properties of alcohols were examined, such as lubricity, viscosity, calorific value, and cetane number, and their combustion characteristics in compression ignition engines provide a comprehensive review of their potential biofuels as alternative fuels. Full article

Higher carbon alcohols such as n-propanol, n-butanol, and n-pentanol that can be produced from biomass can be used as alternative fuels in diesel engines. These alcohols can mix with both diesel fuel and biodiesel without any phase separation. Currently, unregulated emissions such as toxicity and total polycyclic aromatic hydrocarbon (PAH) from the use of these alcohols are not monitored. Investigating the effects of increasing the alternative fuel concentration for use in a diesel engine on PAH emissions will contribute to the protection of the environment and extend the engine’s operating life. In this study, the effects of adding 35% (by volume) n-propanol, n-butanol and n-pentanol to diesel and biodiesel on unregulated emissions in a diesel engine were compared. In the total PAH emission of biodiesel, the mixture containing n-pentanol stood out compared to other mixtures with a decrease of 39.17%. In higher alcohol-diesel mixtures, the highest reduction was observed in the n-butanol mixture as 80.98%. With respect to toxic emissions, very close values were obtained in biodiesel blends up to 94.15%, although n-butanol showed a maximum reduction of 84.33% in diesel blends. All these reductions also prevented the formation of high-cycle PAHs. The results obtained showed that the use of high carbon alcohols in a high mixing ratio contributed to the improvement of the fuel properties of biodiesel and to an increase in the alternative fuel mixing ratio with the reduction of PAH emissions from diesel fuel. Full article