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Spray evaporation characteristics of isopropanol-butanol-ethanol (IBE)/diesel blends in a constant volume chamber
Abstract
As an intermediate fermentation product of butanol, isopropanol-butanol-ethanol (IBE) can be used as an alternative fuel for diesel directly to reduce the separation and purification costs during the butanol fermentation process. However, how the properties of IBE affect the spray evaporation characteristics of diesel is rarely studied. In this regard, IBE was blended into diesel at various volumetric ratios and then tested in a constant volume chamber using Mie scattering method. The experimental results show that after blending IBE into diesel, the spray evaporation characteristics improve noticeably. The more IBE blended into diesel, the shorter liquid spray penetration and smaller spray area are. However, the reduction of the liquid spray penetration and spray area are not linear, they exhibit a huge drop when the IBE to diesel ratio increases from 60% to 80% in volume. With more IBE blended into diesel, the time for the spray to reach the stable stage decreases. Results also show that the ambient temperature has great effects on both the spray evaporation of pure diesel and IBE/diesel blends. As the ambient temperature rises, their spray jets become smaller, and the corresponding liquid spray penetration become shorter. That means elevate the ambient temperature can further improve the spray evaporation of IBE/diesel blends.
... To avoid high-temperature damage to the glass window and keep a constant nozzle tip temperature, we inserted a cooling system into the cham- Table 1 Fuel properties of n-butanol and diesel (C. Zhang et al., 2022;Tipanluisa et al., 2021;Z. Zhang et al., 2022;Csemány et al., ...
In this paper, the spray and combustion characteristics of diesel/butanol-blended fuels were studied within a high-temperature and high-pressure constant volume chamber equipped with a single-hole injector. Two blends with 80% diesel/20% butanol and 60% diesel/40% butanol mixed by volume were tested in this study. The pure diesel B0 was also tested here as a reference. The spray penetration, flame lift-off length, and soot optical thickness were obtained through high-speed schlieren imaging, OH* chemiluminescence, and diffused back-illumination extinction imaging technique, respectively. The thermogravimetric curves of different fuels were obtained through a thermogravimetric analyzer. The results showed that butanol/diesel blends presented a longer ignition delay (ID) and flame lift-off length compared with pure diesel, and such finding was mainly caused by the lower cetane number and higher latent heat of vaporization of n-butanol. With the increase in the n-butanol ratio, soot production in the combustion process decreased significantly. Given the shorter ID period, the soot distribution of pure diesel reached a steady state earlier than the blends.
... After combining IBE with diesel, spray evaporation characteristics vastly improve, according to experimental findings. Moreover, the ambient temperature had a significant effect on the spray evaporation of both pure diesel and IBE/diesel blends, with an increase in temperature resulting in smaller spray streams [38]. To enhance the pre-evaporation of liquid spray in confined spaces, electrostatic fields to control the location of electrically charged droplets of fuel have been studied [39]. ...
Due to the current global crises related to fossil fuels (prices up and sources shortage) and in order to diminish the remnants and the negative effects of harmful gas emission (CO and NOx), the fielded researchers and academics try to find alternative source of fossil fuel. Bio fuels consider one of promised source of clean energy. Palm vegetable oil widely separated in Malaysia which considered one of dominant production of this oil globally. Atomization and evaporation radically represent a challenge when using liquid fuel especially fuels with high viscosity and density which is not easy to atomize and evaporate without pre-heating or blende it. A numerical investigation has been proposed to do comparison between two different external evaporative chamber and internal evaporation without using conventional liquid fuel evaporation methods. Findings revealed that both configurations have a good performance in term of emission concentrations and turbine inlet temperature (TIT) which was about 899 C with chamber using internal recycle tube evaporation with CO emission about 183 ppm with outer pre-evaporation chamber. Chamber with internal evaporation was chosen due to technical and fabrication reasons. Besides that, a six different inlet and exhaust ducting ports tested with the chosen chamber with internal recycle tube evaporation chamber, all configurations revealed a non-symmetrical flame flow near chamber exhaust which is not desirable as it will cause turbine unstable operation. The configuration with square duct exhaust was suitable with stable and symmetric flame flow field and slight small CO emission about 312 ppm.
... The results indicated that fuel properties, in particular, fugacity, significantly influence the phase change mechanism in a spray and droplet evaporation rate. Zhang, et al. [7] estimated the effect of isopropanol-butanol-ethanol (IBE) addition on diesel spray evaporation characteristics in a constant volume chamber using Mie-scattering imaging. They concluded that saturated vapor pressure (SVP), surface tension, and viscosity of the fuels are the key parameters that would promote droplet breakup and further accelerate fuel evaporation. ...
div class="section abstract"> Spray evolution in diesel engines plays a crucial role in fuel-air mixing, ignition behavior, combustion characteristics, and emissions. There is a variety of phenomenological spray models and computational fluid dynamics (CFD) simulations have been applied to characterize the spray evolution and fuel-air mixing. However, most studies were focused on the spray phenomenon under a limited range of injection and ambient conditions. Especially, the prediction of spray geometry in multi-hole injectors remains a great challenge due to the lack of understanding of the complicated flow dynamics. To overcome the challenges, a series of spray experiments were carried out in a constant volume spray chamber (CVSC) coupled with high-speed Mie-scattering imaging to obtain the spray characteristics at various injection and ambient conditions. Based on the data set, the spray geometry (e.g., penetration, cone angle, spray tip velocity, area), shot-to-shot probability, and plume-to-plume variation were estimated. Furthermore, the artificial neural network (ANN) is introduced to predict the key parameters of the spray geometry to avoid the prediction errors of the existing mathematical models, and the optimal model is determined to facilitate future prediction of the spray geometry of the fuel based on the data set for algorithm training. The quantitative validation results showed that the ANN model is capable of predicting spray performance with acceptable accuracy.
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div class="section abstract"> Aluminum oxide (Al₂O₃) nanoparticles are considered a promising fuel additive to enhance combustion efficiency, reduce emissions, and improve fuel economy. This study investigates the spray characteristics of diesel fuel blended with aluminum oxide nanoparticles in a constant volume chamber. The blends were prepared by dispersing Al₂O₃ nanoparticles in diesel at varying concentrations (25, 50, and 100 mg of aluminum oxide nanoparticles into 1 L of pure diesel, respectively) using a magnetic stirrer and ultrasonication to ensure stable suspensions. Spray characterization was conducted in a high-pressure and high-temperature constant volume chamber, simulating actual engine conditions. The ambient temperatures for this experiment were set from 800 to 1200 K, and the oxygen concentrations were set from 21% to 13%. The study focused on key spray parameters such as spray penetration length, spray angle, and spray area, analyzed using high-speed imaging and laser diffraction techniques. Images of the spray evolution process for tested blends were also captured to reveal the effects of nanoparticles on spray characteristics. Results showed that the addition of Al₂O₃ nanoparticles altered the spray behavior, with changes in spray penetration length compared to pure diesel. Furthermore, the effects of varying nanoparticle concentrations on the spray characteristics were evaluated, revealing an optimal concentration that balances improved atomization without significantly increasing fuel viscosity. This research highlights the potential of Al₂O₃ nanoparticle-diesel blends as a promising alternative fuel for diesel engines, offering insights into their spray dynamics under controlled conditions. The findings provide a foundational understanding for further exploration of nanoparticle additives in fuel blends, aiming at optimizing engine performance and emissions.
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div class="section abstract"> Methanol is an main type clean energy and it taken important part for the future internal combustion engine technology. The Equivalent air-fuel ratio (AFR) is very import for the engine combustion of methanol. And a lot of case the ratio between methanol and gasoline is not the constant number. There are no studies about AFR when fuel ratio is arbitrary in the currently. The AFR changes obviously if the tank was fueled with gasoline by mistake at a methanol spark ignition engine. Emission will be affected heavily at this situation because the AFR of gasoline is 2 times more than methanol. Some fuel trim adaptation error will be detected by engine controller or even the engine will stall if engine controller keep use the previous AFR to do the fuel injection control. The Investigation provide a relevant AFR adaption strategy based on lambda sensor and the fuel pipes configuration. The strategy was proved valid by some simulation cases to reduce lambda disturbance, optimize emission property and increase driving safety.
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This study investigates the behavior of a single droplet exposed to high-temperature ambient air and macroscopic spray characteristics of various ternary blends of diesel-ethanol-jatropha oil. The experiments on single droplet are performed at ambient pressure and high temperature. The spray experiments are performed under high-pressure and high-temperature conditions, similar to those of a diesel engine in-cylinder air at the time of fuel injection for three blends. The D50E35J15 has exhibited micro explosion behavior, D50E30J20, which has shown puffing, and D60E20J20, which has demonstrated both micro explosion and puffing during single droplet experiments, are selected for spray experiments. A constant volume spray chamber with optical access equipped with an electric heater was used to study evaporating spray characteristics of the blends at 5 MPa and 900 K. The spray experiments have shown that the ternary fuel blends have higher liquid penetration as compared to that of diesel due to the higher boiling point of jatropha oil. The variation in the spray cone angle between the different blends was found to be insignificant and within the measurement's uncertainty limits. Thus, the blends which have exhibited micro-explosion and puffing in droplet experiments, have not affected the macroscopic spray characteristics at higher ambient pressures.
Isopropanol‐butanol‐ethanol (IBE) is considered to be a promising alternative fuel for diesel to reduce soot emissions. However, currently researchers have not yet revealed its soot formation processes. In this regard, the forward illumination light extinction (FILE) technology was used to investigate the soot formation process of IBE/diesel blends. Diesel containing 50% of IBE in volume (IBE50), pure IBE (IBE100), and diesel were tested. The experimental results show that soot formation regions for the tested fuels are greatly affected by the ambient conditions. The lower the ambient temperature is, the smaller the soot formation region is. Besides, a low ambient temperature coupled with a small ambient oxygen concentration may further reduce soot formation regions of the tested fuels. Results also show that soot formation regions of IBE50 and IBE100 are obviously smaller than that of diesel. In most test conditions, the head of soot formation regions for IBE50 and IBE100 exhibits as a thin strip. Furthermore, soot formation duration and intensity of IBE50 and IBE100 are obviously small in comparison with diesel, especially at low ambient temperature. The results of this study indicate that when IBE is directly blended with diesel, it is able to reduce soot emissions.
This study investigates the impact of an acetone-butanol-ethanol (ABE) mixture on spray parameters, engine performance and emission levels of neat cottonseed biodiesel and neat diesel blends. The spray test was carried out using a high-speed camera, and the engine test was conducted on a variable compression diesel engine. Adding an ABE blend can increase the spray penetration of both neat biodiesel and diesel due to the low viscosity and surface tension, thereby enhancing the vaporization rate and combustion efficiency. A maximum in-cylinder pressure value was recorded for the ABE-diesel blend. The brake power (BP) of all ABE blends was slightly reduced due to the low heating values of ABE blends. Exhaust gas temperature (EGT), nitrogen oxides (NOx) and carbon monoxide (CO) emissions were also reduced with the addition of the ABE blend to neat diesel and biodiesel by 14–17%, 11–13% and 25–54%, respectively, compared to neat diesel. Unburnt hydrocarbon (UHC) emissions were reduced with the addition of ABE to diesel by 13%, while UHC emissions were increased with the addition of ABE to biodiesel blend by 25–34% compared to neat diesel. It can be concluded that the ABE mixture is a good additive blend to neat diesel rather than neat biodiesel for improving diesel properties by using green energy for compression ignition (CI) engines with no or minor modifications.
The recent transport electrification trend is pushing governments to limit the future use of Internal Combustion Engines (ICEs). However, the rationale for this strong limitation is frequently not sufficiently addressed or justified. The problem does not seem to lie within the engines nor with the combustion by themselves but seemingly, rather with the rise in greenhouse gases (GHG), namely CO2, rejected to the atmosphere. However, it is frequent that the distinction between fossil CO2 and renewable CO2 production is not made, or even between CO2 emissions and pollutant emissions. The present revision paper discusses and introduces different alternative fuels that can be burned in IC Engines and would eliminate, or substantially reduce the emission of fossil CO2 into the atmosphere. These may be non-carbon fuels such as hydrogen or ammonia, or biofuels such as alcohols, ethers or esters, including synthetic fuels. There are also other types of fuels that may be used, such as those based on turpentine or even glycerin which could maintain ICEs as a valuable option for transportation.
This study is focused on artificial neural network (ANN) modelling of non-modified diesel engine keyed up by the combination of two low viscous biofuels to forecast the parameters of emission and performance. The diesel engine is energised with five different test fuels of the combination of citronella and Cymbopogon flexuous biofuel (C50CF50) with diesel at precise blends of B20, B30, B40, B50 and B100 in which these numbers represent the contents of combination of biofuel and the investigation is carried out from zero to full load condition. The experimental result was found that the B20 blend had improved BTE at all load states compared with the remaining biofuel blends. At 100% load state, BTE (31.5%) and fuel consumption (13.01 g/kW-h) for the B20 blend was closer to diesel. However, the B50 blend had minimal HC (0.04 to 0.157 g/kW-h), CO (0.89 to 2.025 g/kW-h) and smoke (7.8 to 60.09%) emission than other test fuels at low and high load states. The CO2 emission was the penalty for complete combustion. The NOx emission was higher for all the biodiesel blends than diesel by 6.12%, 8%, 11.53%, 14.81% and 3.15% for B20, B30, B40, B50 and B100 respectively at 100% load condition. The reference parameters are identified as blend concentration percentage and brake power values. The trained ANN models exhibit a magnificent value of 97% coefficient of determination and the high R values ranging between 0.9076 and 0.9965 and the low MAPE values ranging between 0.98 and 4.26%. The analytical results also provide supportive evidence for the B20 blend which in turn concludes B20 as an effective alternative fuel for diesel.
The current investigation has been aimed at the effective utilization of the alternative renewable feedstock towards propelling the diesel engine. A novel alternative feedstock, which is abundantly present in the south of India, Mimusops elengi was identified for this present investigation. The study was initiated with 20% of Mimusops elengi and methyl ester (B20) was blended with fossil diesel fuel on a volume basis. Moreover, it was observed that on the trade-off between the performance characteristics; the emission quantity was marginally higher. Concentrating on the environmental pollution caused by the diesel engine, an oxygenated nano additive, titanium oxide, was doped with the base fuel at different mass fractions of 25, 50, 75, and 100 parts per million (ppm). The result observed states that B20 with 25 ppm of titanium oxide nanoparticle (B20 + 25 ppm) established a 3.60% improvement in BTE (brake thermal efficiency) as equated with B20; furthermore, it resulted in 14.2% and 17.4% reduction in hydrocarbon and smoke emission, respectively, though it resulted in a marginal penalty of 14.72% in NOx.
In the current scenario, the use of fossil fuel is increasing sharply in the global energy store and playing a highly hazardous role in the ecological system, besides contributing to global warming. Biodiesel is one of the most credible keys for addressing this issue. The present experimental study has been done on Kirloskar make TAF-1 model compression ignition (CI) engine, powered by Garcinia gummi-gutta methyl ester (GGME) biodiesel and its blends. Experimental results were correlated with those of mineral diesel. To start with, biodiesel was synthesized from Garcinia gummi-gutta seed oil, assisted by novel Thermomyces lanuginosus lipase (TL) enzyme linked biocatalyst transesterification. Using nanotechnology, ferric oxide (Fe 3 O 4 ) nanoparticles were prepared using the coprecipitation method. The TL enzymes were covalently linked with magnetic Fe 3 O 4 nanomaterial, powered using the immobilization method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR) analyses. A large quantity of TL functional groups attached with Fe 3 O 4 magnetic nanoparticle in reaction with an active functional group in oils leads to improved efficiency and effective recycling via an external magnetic field. At the end of 74 h of reaction time with confined optimization conditions, the transesterification process yielded 93.08 % GGME. All the physiochemical properties of GGME blends were investigated as per ASTM standards. Raw GGME was blended with mineral diesel in various proportions, namely B10, B20, B30, B40, and B100. The fuel blends were analyzed in terms of combustion, performance, and emission characteristics. Test results revealed B20 (20 % GGME + 80 % diesel) blend as on par with mineral diesel in terms of brake thermal efficiency (BTE), unburned hydrocarbon (UBHC), and carbon dioxide (CO 2 ), followed by nitrogen oxides (NO x ) and smoke emissions. At 100 % load, cylinder pressure, the heat release rate (HRR), brake specific energy consumption (BSEC), and carbon monoxide (CO) emissions of B20 were significantly lower than mineral diesel. Overall, B20 was showcased as a reliable alternative fuel for the CI engine.
Alcohols, especially n-butanol, have received a lot of attention as potential fuels and have shown to be a possible alternative to pure gasoline. The main issue preventing butanol’s use in modern engines is its relatively high cost of production. ABE, the intermediate product in the ABE fermentation process for producing bio-butanol, is being studied as an alternative fuel because it not only preserves the advantages of oxygenated fuels, but also lowers the cost of fuel recovery for individual component during fermentation. With the development of advanced ABE fermentation technology, the volumetric percentage of acetone, butanol and ethanol in the bio-solvents can be precisely controlled. In this respect, it is desirable to estimate the performance of different ABE blends to determine the best blend and optimize the production process accordingly. In this paper, pure ABE fuels with different component volumetric ratio, (A:B:E of 3:6:1, 6:3:1 and 5:14:1), were combusted in a naturally aspirated, port-fuel injected spark ignited engine. The performance of these blends was evaluated through measurements of in-cylinder pressure, and various exhaust emissions. In addition, pure gasoline and neat n-butanol were also tested as baselines for comparison of ABE fuels. The tests were conducted at an engine speed of 1200 RPM and loads of 3 and 5 bar brake mean effective pressure (BMEP) under different equivalence ratios. On the basis of the experimental data, the combustion characteristics and emission behavior of these fuels have been presented and discussed. It was found that in terms of thermal efficiency, ABE(6:3:1) might be much better suited for use as an alternative fuel, relative to ABE(3:6:1) or n-butanol.
Acetone-butanol-ethanol (ABE), as the intermediate product during producing biobutanol by fermentation, is considered as a promising alternative fuel due to its advanced properties and lower recovery cost. The spray and combustion process of ABE20 (20% ABE and 80% diesel) and pure diesel was investigated in a constant volume chamber. The tested ambient environments were set at different temperatures (1100 K, 900 K, and 700 K) and oxygen contents (21%, 16%, and 11%) to cover conventional combustion and low temperature combustion (LTC) conditions of diesel engines. The results show that with the addition of 20% ABE, blends exhibit an improved spray characteristics, shorter and narrower spray due to the low viscosity and high volatility of ABE components, and the spray performance impacted much less by environmental condition than that of neat diesel. In addition to the shorter spray penetration, ABE20 also exhibits a much longer flame lift-off length (FLoL) than that of neat diesel, which forms a much bigger gap from spray tip to flame area for ABE20 that will effectively reduce equivalence ratio of combustion region. As a result, the natural flame luminosity which represents the soot emission level of ABE20 is significantly lower than that of pure diesel (D100) at all tested conditions.
For spark-ignition direct-injection (SIDI) engines in which fuel is injected directly in the cylinder, large amount of in-cylinder mixture variation on a cyclic basis could adversely influence the combustion quality and lead to more fuel consumption and excessive engine emissions. In this study, multiple cycles of intake air flow fields and their effects on fuel spray structure were investigated experimentally in an optical SIDI engine. Proper orthogonal decomposition (POD) was utilized to identify and quantify the cyclic variations of intake air motions and spray the pattern in the cylinder. Results show that the pattern of POD mode 1 resembles the ensemble-averaged structure of intake air velocity field. Other higher POD modes are useful to identify the fluctuations of the flow. The cycle-to-cycle difference of in-cylinder air flow motion also influences the variations of spray structure on a cyclic basis, which can be unambiguously quantified by analyzing the POD modes 1 and 2 of the spray pattern. Whereas the first mode exhibits the variation for the dominant portion of spray structure, the second mode captures the subtle differences in the positions of discrete fuel spray plumes under the influence of intake air. Overall, POD can be useful in identifying and quantifying the cyclic variations of the intake air motion and spray structure in the cylinder of running engine conditions.
The multiple-injection strategies can significantly improve the diesel engine startability at low-temperature conditions, but the processes are extremely complex due to the effect of various factors simultaneously. To find out how the pilot injection affects the main injection, the spray and ignition with different injection strategies at low temperatures, and the effect of the interaction of the pilot and main injections on mixing and ignition are studied numerically. The results show that the main injection fuel can catch up with the pilot injection which has been pre-heated, making the peripheral fuel of the main injection has a higher temperature and equivalence ratio compared to the single injection, which can accelerate the chemical reaction process and thus shorten the ignition delay. The products of the pre-reacted pilot fuel are mixed with the peripheral fuel of the main injection and affect the reaction process. The pre-injected fuel can promote the combustion and shorten the ignition delay of the main injection fuel because the remaining species of pre-injected fuel can make n-dodecane dehydrogenated with the intermediate products such as OH in preference to O2. However, mixing the injections too late prevents the pre-injected fuel from promoting the combustion of the main injection. The concentration of CH2O increases rapidly during the first heat release, and the species at this moment significantly inhibit the combustion of the new fuel.
Currently, idling emissions and old vehicle emissions have attracted more and more attention. Many countries have made corresponding policies to limit these emissions. In this study, to investigate the combustion, engine performance, and emission characteristics of an old diesel engine fueled with diesel-palm biodiesel-ethanol (DPE) ternary blended fuels according to various multiple injection strategies under low idling conditions, a series of experiments were carried out on an old common-rail direct injection (CRDI) diesel engine. The engine speed and load were fixed at 750 rpm (the lowest speed) and 30 Nm, respectively. Two test modes of A (only pilot injection timing was variable) and B (only main injection timing was variable) were comparative studied. The experimental results show that the main-pilot injection timings and DPE ternary blends have significant impacts on the engine performance, combustion and characteristics. Overall, as the ethanol concentrations in DPE ternary blends increase, brake specific fuel consumption (BSFC), maximum heat release rate (HRRmax), ignition delay, carbon monoxide (CO) and hydrocarbon (HC) emissions increase, while nitrogen oxides (NOx) and smoke emissions are simultaneously reduced. The high volatility, high latent heat of evaporation and high oxygen content of ethanol may play a major role in reducing NOx and smoke emissions. In addition, the primary particle diameter of all tested fuels is distributed in a narrow range of 18–24 nm, and the addition of ethanol is beneficial to reduce the particle diameter.
For diesel engines, the distance between the wall and the spray nozzle is an important feature for the matching of spray and combustion chamber geometry. In this study, the effects of the cold wall with different wall distance on the spray and ignition characteristics at low-temperature conditions are systematically analyzed. CFD simulations are used to reproduce and explain the phenomena in optical experiments, and the chemical kinetics analysis is used to investigate the microscopic influence of the cold wall on the chemical reactions. The results show that the cold wall has little influence on the ignition when the wall distance is larger than a critical distance which is determined by the proportion of vapor phase in the impinged fuel and the chemical reaction degree at the time of impingement. As the wall distance reduces, the fuel evolution process is more inclined to the route of low temperature and low concentration, causing the delay of chemical reactions, and the misfire occurs when the time required for chemical reactions exceeds the time of fuel dissipation. Moreover, varying wall distance changes the timing of the local fuel cooling, which leads to diverse effects. During the transition from low-temperature reaction to high-temperature reaction, earlier the fuel cooling leads to a more substantial inhibition effect. The fuel cooling after the start of the high-temperature reactions has little impact on the chemical reaction.
The entrainment coefficient reflects the air-fuel mixing quality, which is one of the foremost concerns for the development of cleaner and higher power-density internal combustion engines. Previous prediction models constructed by the change of axial mass flow rate have lower accuracy under high injection pressure conditions. During modeling in the work, a new construction method based on local entrainment velocity and local entrainment area is developed, and the influences of dilution effect and forces such as flow resistance, lateral pressure, etc. on local entrainment velocity are considered. With the modified model, its prediction accuracy can be effectively extended to high injection pressure and detailed information about entrainment can be provided for analysis. It is found that, with the increase of injection pressure, the entrainment coefficient rises in the whole flow field. When increasing to high injection pressure, the entrainment coefficient constantly decreases with distance in the far-field, which is consistent with the experiments, but not a constant value predicted by previous models. Besides, the decreased rate rises with the increase of injection pressure. Meanwhile, the increase of ambient pressure also makes the entrainment coefficient rise, but barely influences the decreased rate in the far-field. The large decrease of local entrainment velocity in the far-field caused by strong resistance can explain the decrease of entrainment coefficient with distance. Overall, the modified model can rapidly predict the spray mixing quality over a wider range of operating conditions and provide more detailed entrainment information for analysis.
In relative to traditional combustion, the reactivity-controlled compression ignition (RCCI) technique using fuels with different reactivity has gained significant interest because of its high thermal efficiency and low NOx and smoke emissions. Hence, the present work investigates the RCCI mode of operation in a light-duty diesel engine by introducing Cottonseed oil biodiesel as high reactivity fuel directly into the combustion chamber and n-pentanol as low-reactivity fuel intake. The experimental results revealed that NOx and smoke emissions were considerably decreased by 44.2% and 35.0% with RCCI mode of operation compared to Cottonseed oil biodiesel-based operation mode at 100% load condition. However, a significant rise in emissions of unburnt hydrocarbon (HC) and carbon monoxide (CO) was noted at medium load (50%) conditions in reactivity-controlled compression ignition mode but emissions of HC and CO tended to decrease at peak load conditions. Moreover, the en-gine's brake thermal efficiency was found to increase by 7% when operating under RCCI mode at 20% of the n-pentanol share, although a marginal reduction in brake thermal efficiency was recognized in the case of above 20% energy share at 100% engine load. Considering the combustion characteristics, the RCCI mode working on Cottonseed oil biodiesel/n-pentanol showed substantial improvement in peak pressure and heat release rate compared with the single-fuel mode. Overall, it has been identified that the operation of diesel engines on RCCI mode could result in a simultaneous reduction of smoke opacity (up to 21.2%) and NOx emission (up to 36%) and a marginal improvement in the engine performance.
In this study, anhydrous ethanol was directly mixed with diesel fuel and applied to an old diesel engine to improve nitrogen oxides (NOx)-smoke trade-off relationship. Multiple injection strategies (MISs) including various main-pilot injection combinations were selected as the main variables. The results demonstrated that the diesel fuel could be mixed with up to 15% ethanol by volume without phase separation at room temperature. The influence of MISs on the cylinder pressure and heat release rate (HRR) was greater than that of the diesel/ethanol blends. Adding ethanol to diesel fuel had nearly no effect on the peak cylinder pressure, but delayed the start of combustion, greatly increased the peak value of HRR and ignition delay, and reduced the combustion duration. The coefficient of variation of the indicated mean effective pressure (COVimep) and maximum pressure raise rate of all test fuels under all test additions were less than 3% and 3 bar/°CA, far below their limits, indicating that this diesel engine without any modifications can run well with these diesel/ethanol binary blends. The most interesting result was that the addition of ethanol to diesel fuel could simultaneously reduce NOx and smoke emissions as well as particle diameter.
Currently, diesel engine specialists and experts have established that combination of biodiesel higher alcohols and gaseous fuel can be an apposite substitute for the existing conditions. In the present study, an investigation and analysis were done by fueling a dual fuel engine with blends of diesel, rice bran biodiesel, and n-butanol as liquid fuel and biogas as gaseous fuel. Performance and exhaust emissions parameters of the dual-fuel engine energized with ternary blends utilizing diesel-biodiesel-n-butanol along with biogas were evaluated and compared with baseline diesel. Results depicted that brake thermal efficiency (BTE) was reduced by 14.68% on an average in relation to baseline diesel. Emissions characteristics illustrated that CO and HC emissions on average were higher by 45.58 and 17.74%, while NOx and smoke opacity on an average were lowered by 39.06 and 46.85% in relation to pure diesel. Therefore, utilization of cost-effective gaseous fuel, for instance biogas, would be a feasible recommendation to deal with the existing and upcoming complications of energy insufficiency and accompanying conservational apprehensions.
The number of energy users in the world is growing more significant and more prominent in the current scenario for the automotive sector. About 70% of India’s energy depends heavily on non-renewable fossil fuels. The cost and demand for the fuel are incredibly high. Over and above these reasons, environmental pollution is causing great concern. Consequently, many of the present researchers are focusing on finding a renewable fuel that can become an alternative for fossil fuel that is fast depleting. Biodiesels have drawn much attention from the research community because of their natural characteristics and chemical composition. In this manuscript, we have reported the linseed oil, which is effectively used as biodiesel (B20) and pre-heated to decrease the viscosity of the fuel with the aid of heater up to 100°C. The nanoparticle used in this work is titanium dioxide because of its highest oxygen content and easy availability in the market. Different proportions of titanium dioxide nanoparticles are blended (50 ppm, 100 ppm, 150 ppm, and 200 ppm) with pre-heated linseed oil in a coated diesel engine. The coating material used is Partially Stabilized Zirconium and the preferred thickness of 0.5 mm that is achieved with plasma spray techniques guidance. The crown of the piston or the top surface of the piston is coated with Partially Stabilized Zirconium (PSZ). It is observed that pre-heated PLSNP200 linseed oil has shown the enhanced performance and lower emissions when correlated with all the other blends. Pre-heating of Linseed oil and diesel engine (DI) coating has resulted in a 5.2% increase in thermal efficiency. The combination of PLSNP 200 reduces emissions of CO, smoke, and HC by 37.78%, 25%, and 37.92%, respectively. The oxides of nitrogen are elevated drastically by 7.43% when correlated with diesel fuel. The blend PLSNP200 increased the BTE and NOx by 8.11% and 6.53% respectively when compared with PLS20. The PLSNP200 blend HC, CO and Smoke opacity emission is drastically decreased by 33.82 21.05% and 26.57% when compared with the preheated linseed oil B20 (PLS20).
Acetone-butanol-ethanol (ABE) fermentation process is a promising bioenergy option amid rising concerns over the environmental impact of fossil fuel usage. However, the commercialization of the ABE process has been marred by challenges of low product yield and titer, thereby non-competitive process economics. Here, we coupled cost competitive reducing agents with a controlled feeding strategy to improve both product titer and yield. Reducing agents promote cofactor dependent butanol production, while fed-batch operation enhances glucose consumption, final ABE titer, and partly mitigates product toxicity. The effects of ascorbic acid, L-cysteine, and dithiothreitol (DTT) on ABE fed-batch production using Clostridium acetobutylicum was investigated in current study. NADH, ATP, extracellular amino acid secretion, and NADH-dependent butanol dehydrogenase (BDH) assays were performed to study the metabolic modifications triggered by reducing agents. Incidentally, L-cysteine and DTT improved ABE solvent titer by 2-fold, producing 24.33 and 22.98 g/L ABE with solvent yields of 0.38 and 0.37 g/g, respectively. Elevated NADH, BDH, and ATP levels in fermentation broth reflected in enhanced ABE titer and yield. Furthermore, histidine secretion emerged as an important factor in Clostridial acid stress tolerance in this study. The results demonstrate that addition of reducing agents in fed-batch ABE fermentation operation enables efficient utilization of glucose with significant improvement in solvent production.
Isopropanol-butanol-ethanol (IBE) is a clean and renewable biofuel, but its component ratio effects on the spray combustion process of diesel have not been reported to date. In this study, IBE mixtures with different component ratios (6:3:1, 3:6:1 and 0:10:0) were separately blended into diesel at the volumetric ratio of 20% and then tested in a constant volume chamber. The experimental results show that isopropanol in IBE plays leading role on the spray combustion characteristics of IBE/diesel blends; the more isopropanol in the IBE blend, the shorter the liquid penetration is. Furthermore, the IBE/diesel blends containing more isopropanol always exhibit a long ignition delay but a short combustion duration. Results also show that regardless of whatever type of IBE/diesel blends, the flame lift-off length (FLOL) prolongs and the spatial integrated natural flame luminosity (SINL) reduces. However, the magnitudes of reduction of the SINL for the IBE/diesel blends vary with the component ratio of IBE. The IBE/diesel blends containing more isopropanol always present a noticeably lower SINL. Compared with pure diesel, the fuel blends containing more isopropanol are capable of reducing the time integrated natural luminosity (TINL) almost by half in most test conditions. That is to say, increasing isopropanol ratio in IBE can reduce the soot formation of IBE/diesel blends but the increase of the butanol ratio has an opposing trend.
Isopropanol-butanol-ethanol (IBE) can be utilized as a clean transportation fuel to avoid the production cost of bio-butanol as well as the plastic-degradation issues of acetone-butanol-ethanol (ABE). In light of this, optical experiments were conducted in a constant volume chamber under various test conditions to reveal the spray, combustion, and flame structure of IBE/diesel blends. The experimental results show that with the addition of IBE into diesel, the spray evaporation improves significantly; the larger the IBE blending ratio is, the shorter the liquid spray penetration. However, the addition of IBE causes the maximum combustion pressure and peak apparent heat release rate to reduce. Compared with diesel, the flame lift-off length (FLOL) of the fuel blends is noticeably longer. Furthermore, it prolongs as the amount of IBE in the blend increases. The long FLOL of the fuel blends combined with its short liquid spray penetration contributes to a large mixing area for fuel to evaporate, which reduces the local equivalence ratio. Results also show that the fuel blends always give a lower spatial integrated natural luminosity (SINL) than diesel. The SINL curve gradually gets narrower as the IBE blending ratio increases. That is to say, the addition of IBE into diesel can reduce the rate of soot formation but accelerate the soot oxidation.
Biobutanol has demonstrated to be a superior alternative biofuel in internal combustion engine (ICEs). Acetone-butanol-ethanol (ABE) fermentation engineering is a typical technique for biobutanol production. However, the high costs and extra energy consumption in recovery process of biobutanol from intermediate fermentation solvent (i.e. ABE mixture) has obstructed its large-scale application. It is gaining increasing attention to investigate ABE as a potential alternative biofuel. ABE production and ABE combustion in ICEs have been widely studied, but these studies are rarely reviewed to favor understanding and popularization for ABE so far. In this work, the updated progress of ABE fermentation techniques is first summarized from the aspects: (i) selection of suitable strain; (ii) availability of cheaper substrates; (iii) development of fermentation engineering. Then, the research on ABE combustion in ICEs are concluded from the aspects: (i) physicochemical properties and tests in ICEs of ABE components; (ii) substitute for diesel in compression ignition engines; (iii) substitute for gasoline in spark ignition engines. These studies demonstrate that ABE is a better alternative for gasoline or diesel fuel due to the environmentally benign manufacturing process and the potential to improve energy efficiency and reduce pollutant emissions. However, ABE has not been intensively studied when compared to conventional alternative fuels (e.g. ethanol, butanol, biodiesel, etc.), for which considerable numbers of reports are available. Therefore, some challenges and future research directions are outlined in the end. This review is helpful for finding opportunities to make ABE as a feasible alternative biofuel in near future.
An experimental study was conducted in a port-fuel injection (PFI) spark-ignition (SI) engine fueled with acetone-butanol-ethanol (ABE) and gasoline. 30 vol% ABE blends with different component ratios (A:B:E = 3:6:1, 6:3:1, and 5:14:1), referred to as ABE(3:6:1)30, ABE(6:3:1)30, and ABE(5:14:1)30, were used as test fuels. Additionally, 30 vol% ethanol and 30% vol.% butanol blended with 70 vol% gasoline, referred to as E30 and B30, respectively, were also used as test fuels. Both the regulated emissions, which include unburned hydrocarbons (UHC), carbon monoxide (CO), and nitrogen oxide (NOx), and unregulated emissions, including acetaldehyde, 1,3-butadiene, benzene, toluene, ethylbenzene, and xylene (BTEX), were investigated under various conditions. The experiments were conducted at an engine speed of 1200 rpm and at engine loads of 3, 4, 5, and 6 bar brake mean effective pressure (BMEP) under various equivalence ratios (φ = 0.83–1.25). The results indicated that ABE(6:3:1)30 had the lowest UHC and CO emissions, with ABE(3:6:1)30 having slightly higher NOx emissions. As for unregulated emissions, B30 showed the highest acetaldehyde emission and ABE(6:3:1)30 had the lowest among all the fuel blends. ABE(3:6:1)30 and ABE(6:3:1)30 showed a reduction in 1,3-butadiene emission. Regarding the BTEX emissions, an overall reduction was observed for all the fuel blends, with ABE(3:6:1)30 having shown the lowest BTEX emissions among all the test fuels. The results indicate that ABE could be used as a promising alternative fuel in SI engines, owing to the reduction in emissions.
Acetone-butanol-ethanol (ABE) fermentation from food processing waste is one way to reduce cost. In this study, corncob hydrolysate and corn steep liquor (CSL), two waste materials from corn processing industries, were used as carbon and nitrogen sources to yield butanol by using Clostridium beijerinckii SE-2. Media compositions favoring butanol production were investigated using statistical experimental designs. Media components were first screened using a fractional factorial experimental design. CSL and CH3COONH4 were found to be the significant variables among six factors, including the contents of CSL, CH3COONH4, K2HPO4-KH2PO4, MnSO4 · H2O, MgSO4 · 7H2O and FeSO4 · 7H2O. The two factors were further optimized by the steepest assent and central composite rotatable design. The validated experiments showed that the total ABE in the system was 19.22 g L⁻¹ and the concentration of butanol could reach 11.65 g L⁻¹ with the optimized medium, which was 42% higher than the initial medium. Scale-up fermentation with optimized medium in the 100 L bioreactor resulted in 20.29 g L⁻¹ of ABE and 11.92 g L⁻¹ of butanol. Moreover, C. beijerinckii SE-2 can use both glucose and xylose from corncob hydrolysate. In conclusion, our study suggested that the waste of the corn processing industry can be used as sources to produce butanol by Clostridium, and statistical experimental designs are a useful approach for optimizing media compositions for butanol production.
Isopropanol-butanol-ethanol (IBE) can be used in engines as an alternative fuel to eliminate the high recovery and separation costs in the production of butanol and also to avoid the corrosivity and low flash point of acetone in acetone-butanol-ethanol (ABE). In this respect, this study is aimed to investigate the performance, combustion and emissions of a single-cylinder, common-rail diesel engine fueled with IBE and diesel blends. Two blends of butanol and diesel fuel, denoted as IBE15 (15% IBE and 85% diesel in volume) and IBE30 (30% IBE and 70% diesel in volume) were tested. Additionally, the experiments in this study were conducted at different diluted gas ratios to achieve low NOx emission. The experimental results show that when the intake charger is gradually diluted, the start of combustion and combustion center for all the tested fuels are remarkably delayed. Compared with pure diesel, the brake thermal efficiency (BTE) for IBE15 is always higher. Butt for IBE30, the BTE is lower than that of pure diesel when the flow rate of the dilute gas is less than 30 L/min. For all the tested fuels, NOx emission reduces while CO and HC emissions increase with the increase of dilute gas. Soot emission for pure diesel and IBE15 drastically increases as the dilute gas increases. However, the increase of dilute gas does not cause the soot emission of IBE30 to significant increase. That is to say, IBE30 coupled with a proper EGR ratio has the potential to reduce NOx and soot emissions simultaneously.
Among primary alcohols, bio-n-butanol is considered as a promising alternative fuel candidate. However, relatively low production efficiency and high cost of component recovery from the acetone-n-butanol-ethanol (ABE) or isopropanol-n-butanol-ethanol (IBE) fermentation prevents bio-n-butanol's use in modern engines. Therefore, the purpose of this study is to compare the potential of ABE and IBE as fuel candidate in spark ignition (SI) engine. The combustion, performance and emissions characteristics of the engine without any modifications fueled with ABE- and IBE-gasoline blends were investigated. It was found that IBE-gasoline blends showed an advanced combustion phasing with a shorter initial and major combustion duration compared to gasoline and ABE-gasoline blends. In comparison with ABE10 (10 vol.% ABE blended with gasoline) under various lambda from 0.8 to 1.2 and engine loads of 3 and 5 bar BMEP, IBE10 enhanced brake thermal efficiency by 0.9-1.8% and reduced carbon monoxide, unburned hydrocarbons and nitrogen oxides emissions by 0.9-7.3%, 3.3-25.1% and 1.6-5.9%, respectively. Due to the greater potential to increase energy efficiency and reduce pollutant emissions and more desired properties (less corrosive to the engine parts, higher energy content and octane number, etc.), IBE seems to be more attractive than ABE for fuel application in SI engine.
The use of lignocellulosic hydrolysate is a promising strategy to make fuel and chemical production feasible through biological processes. The major challenges facing this process are the presence of inhibitors in hydrolysate, as furan derivatives and phenolic compounds, and the inefficient consumption of the xylose found in hydrolysate. Therefore, this study aimed to select ideal Clostridium strains and an optimal medium for microbiological production of n-butanol from sugarcane straw hydrolysate with high yield and productivity. From a screening of twelve Clostridium strains, two strains stood out: Clostridium saccharoperbutylacetonicum DSM 14923, by its potential to produce high titer of n-butanol (4.95 g/L from 11.6 g/L glucose and 3.6 g/L xylose), and Clostridium saccharobutylicum DSM 13864, by its capacity to concomitantly consume similar quantities of glucose and xylose. Optimization of culture medium and inoculum preparation allowed an improvement in n-butanol production from 0.65 g/L for 5.39 g/L. Moreover, with optimized medium, a higher tolerance to lignocellulosic hydrolysate was obtained, avoiding a premature end to fermentation at hydrolysate and enabling the cultivation of these strains in 79% pure lignocellulosic hydrolysate. Among all the strains tested for lignocellulosic hydrolysate fermentation, C. saccharobutylicum DSM 13864 has the best performance. This strain, in a culture medium composed by 79% of pure lignocellulosic hydrolysate, showed a consumption of 95% of all sugar available (34 g/L of glucose and 22 g/L of xylose) and a total acetone, n-butanol, and ethanol (ABE) production of 10.33 g/L, being the most suitable strain for n-butanol production using this substrate.
Acetone–Butanol–Ethanol (ABE), the intermediate product in bio-butanol production process using Biological Fermentation Purification technology, has been proposed to blend diesel directly for saving the high energy requirement of separating purity butanol. It is very important to study the sooting tendency of ABE-diesel blends, which determined whether it can be used as a clean alternative fuel. Therefore, in this paper, the smoke point and relationship between flame height and fuel uptake rate for a wide range ratio of ABE (0%, 5%, 10%, 20%, 30%, 50% in volume referred to as D100, ABE5, ABE10, ABE20,ABE30, and ABE50, respectively) were measured using wick-fed burner. Flame heights were captured by a Digital SLR camera and fuel uptake rate were gained from electronic analytical balance. It was observed that flame height versus fuel uptake rate started with a linear relationship, then disjointed points appeared, finally returned linear again. Threshold Sooting Index (TSI) and Oxygen Extended Sooting Index (OESI) calculated from fuel uptake rate and smoke point respectively were used to evaluate the blends’ sooting tendency. ABE-diesel has a lower sooting tendency than butanol-diesel because it owns higher oxygen content and lower carbon content for the same blend ratio. Besides, the contribution of acetone, butanol and ethanol to the intensity of ABE weaken blends’ sooting tendency were tested through increasing their relative concentrations in ABE. Since ethanol and butanol have higher H/C ratio and oxygen content from the view of molecular structure, their content in ABE play a positive role in weakening sooting tendency, while the acetone content in ABE has an opposite effect because of its unsaturation degree.
Among primary alcohols, bio-n-butanol is considered as a promising alternative fuel candidate. However, relatively low production efficiency and high cost of component recovery from the acetone-n-butanol-ethanol (ABE) or isopropanol-n-butanol-ethanol (IBE) fermentation processes hinders industrial-scale production of bio-n-butanol. Hence it is of interest to study the intermediate fermentation product, i.e. ABE and IBE as a potential alternative fuels. However, for fuel applications, the IBE mixture appears to be more attractive than ABE due to more favorable properties of isopropanol over acetone, such as being less corrosive to engine part, higher energy density and octane number. In this study, an experimental investigation on the performance, combustion and emission characteristics of a port fuel-injection SI engine fueled with IBE-gasoline blends was carried out. By comparisons between IBE-gasoline blends with various IBE content (0–60 vol.% referred to as G100-IBE60) and more commonly used alternative alcohol fuels (ethanol, n-butanol and ABE)-gasoline blends, it was found that IBE30 performed well with respect to engine performance and emissions, including brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), carbon monoxide (CO), unburned hydrocarbons (UHC) and nitrogen oxides (NOx). Then, IBE30 was selected to be compared with G100 under various equivalence ratio (Φ = 0.83–1) and engine load (300 and 500 kPa BMEP). Overall, higher BTE (0.04–4.3%) and lower CO (4%), UHC (15.1–20.3%) and NOx (3.3–18.6%) emissions were produced by IBE30 compared to G100. Therefore, IBE could be a good alternative fuel to gasoline due to the environmentally benign fermentation process (from non-edible biomass feedstock and without recovery process) and the potential to improve energy efficiency and reduce pollutant emissions.
Bio-butanol has proved to be a promising alternative fuel in recent years; it is typically produced from ABE (acetone-butanol-ethanol) fermentation from non-edible biomass feedstock. The high costs for dehydration and recovery from dilute fermentation broth have so far prohibited bio-butanol's use in internal combustion engines. There is an interesting in studying the intermediate fermentation product, i.e. water-containing ABE as a potential fuel. However, most previous studies covered the use of water-containing ABE-diesel blends. In addition, previous studies on SI engines fueled with ABE did not consider the effect of water. Therefore, the evaluation of water-containing ABE gasoline blends in a port fuel-injected spark-ignition (SI) engine was carried out in this study. Effect of adding ABE and water into gasoline on combustion, performance and emissions characteristics was investigated by testing gasoline, ABE30, ABE85, ABE29.5W0.5 and ABE29W1 (29 vol.% ABE, 1 vol.% water and 70 vol.% gasoline). In addition, ABE29W1 was compared with gasoline under various equivalence ratios (Φ = 0.83-1.25) and engine loads (3 and 5 bar BMEP). It was found that ABE29W1 generally had higher engine toque (3.1-8.2%) and lower CO (9.8-35.1%), UHC (27.4-78.2%) and NOx (4.1-39.4%) than those of gasoline. The study indicated that water-containing ABE could be used in SI engines as an alternative fuel with good engine performance and low emissions.
The effect of pilot injection timing and pilot injection mass on combustion and emission characteristics under medium exhaust gas recirculation (EGR (25%)) condition were experimentally investigated in high-speed diesel engine. Diesel fuel (B0), two blends of butanol and diesel fuel denoted as B20 (20% butanol and 80% diesel in volume), and B30 (30% butanol and 70% diesel in volume) were tested. The results show that, for all fuels, when advancing the pilot injection timing, the peak value of heat release rate decreases for pre-injection fuel, but increases slightly for the main-injection fuel. Moreover, the in-cylinder pressure peak value reduces with the rise of maximum pressure rise rate (MPRR), while NOx and soot emissions reduce. Increasing the pilot injection fuel mass, the peak value of heat release rate for pre-injected fuel increases, but for the main-injection, the peak descends, and the in-cylinder pressure peak value and NOx emissions increase, while soot emission decreases at first and then increases. Blending n-butanol in diesel improves soot emissions. When pilot injection is adopted, the increase of n-butanol ratio causes the MPRR increasing and the crank angle location for 50% cumulative heat release (CA50) advancing, as well as NOx and soot emissions decreasing. The simulation of the combustion of n-butanol-diesel fuel blends, which was based on the n-heptane-n-butanol-PAH-toluene mixing mechanism, demonstrated that the addition of n-butanol consumed OH free radicals was able to delay the ignition time.
Partial Premixed Compression Ignition (PPCI) in diesel engine is a combustion mode between conventional diesel combustion and Homogeneous Charge Compression Ignition (HCCI) combustion, which has the potential to simultaneously reduce NOX and smoke emissions and also improve thermal efficiency. As a clean and renewable biofuel, n-butanol has many superior properties, such as good miscibility in diesel, low cetane number and high volatility, which make it an attractive alternative or blending component to diesel fuel to achieve PPCI. In this paper, PPCI combustion in a four-cylinder light-duty diesel engine fueled with n-butanol-diesel blends was achieved through early or late injection condition in which the whole amount of fuel was delivered before ignition. The aim of the project was to evaluate the potential in realizing Partial Premixed low temperature combustion with different fuel reactivity and oxygen content. The exploration strategies were focused on the early or late injection timing, injection pressure and load rate to evaluate the effects of n-butanol fuel characteristics on PPCI combustion and emissions. The effects of injection timing and load rate on PM mass-size distribution have also been investigated. Results show that both early and late injections have long premixed duration, which is helpful to form more homogeneous mixtures, making a great improvement on smoke emission. With the increase of n-butanol blending ratio, smoke emission can be reduced by up to 70%, while NOX shows a slight increase under moderate EGR rate. When the load rate is increased, the premixed combustion fraction decreases apparently, leading to a dramatic increase of soot mass due to the short ignition delay. It is meaningful to find that PPCI combustion can be achieved with reasonable injection timing, lower injection pressure, moderate EGR without penalties in fuel consumption when using high n-butanol blending ratios. Moreover, n-butanol-diesel blends can effectively reduce the soot mass when compared with pure diesel, but has little influence on the PM size distribution. Results indicate that n-butanol-diesel blends are more conducive to expand PPCI operating condition and improve engine performance and emissions.
Large efforts are currently being made toward improving internal combustion engine efficiency without degrading overall performance. To this end, advanced combustion strategies that require in-cylinder fuel/air mixtures to be prepared with unprecedented care and exactness are being implemented. Spray-guided stratified-charge operation is an example of one such strategy that offers high efficiency under light-load operation but requires precise fuel injector and combustion chamber design to ensure robust engine performance. Understanding the mixture formation processes aids in the success of such strategies and is therefore an important goal for internal combustion engine research. Direct visualization via optical diagnostics remains one of the most powerful tools for gaining insight into in-cylinder mixing processes, such as liquid fuel spray atomization. Although substantial efforts have been made over the last few decades to develop and implement liquid fuel spray diagnostics in the challenging in-cylin
The use of alternative fuels, as biodiesel and ethanol, for light duty CI engines to approach the target of ultra low NOx and PM emissions without fuel economy penalty has been widely investigated. Recently, it is growing the interest in the butanol as a viable alternative either single or blended with conventional based fuels both to cut the demand for fossil fuel and to reduce emissions of particulate matter without significantly increasing in NOx.
In this paper, butanol effects on combustion process were investigated through conventional methods and optical diagnostics. First, blends of 80% diesel and 20% n-butanol (BU20) were used in a four cylinder, turbocharged, water cooled, DI diesel engine, equipped with a common rail injection system. Management of timing and injection pressure was carried out to achieve conditions in which the almost total amount of fuel was delivered before auto-ignition. BU20 allowed to attain almost smokeless emissions at lower injection pressure (100 MPa) than diesel fuel (120 MPa). Smokeless conditions were achieved with a slight increase in NOx emissions (around 20%) and a minor penalty for the specific fuel consumption.
Afterward, the blends effects on the combustion process were studied in the combustion chamber of a single cylinder compression ignition engine equipped with the same common rail multi-jets injection system. Spray combustion and pollutant formation were investigated by UV–visible digital imaging and natural emission spectroscopy. UV–visible emission spectroscopy was used for the detection of the chemical markers of combustion process. Chemiluminescence signals, due to OH, HCO and CO2 emission bands were detected. OH emission was correlated to NOx measured at the exhaust. The soot spectral feature in the visible wavelength range was related to the engine out soot emissions.
The combustion characteristics of acetone–butanol–ethanol (ABE) and diesel blends were studied in a constant volume chamber under both conventional diesel combustion and low temperature combustion (LTC) conditions. In this work, 20 vol.% ABE without water (ABE20) was mixed with diesel and the vol.% of acetone, butanol and ethanol were kept at 30%, 60% and 10% respectively. The advantageous combustion characteristics of ABE-diesel include higher oxygen content which promotes soot oxidation compared to pure diesel; longer ignition delay and soot lift-off length allowing more air entrainment upstream of the spray jet thus providing better air–fuel mixing. Based on the analysis, it is found that at low ambient temperature of 800 K and ambient oxygen of 11%, ABE20 presented close-to-zero soot luminosity with better combustion efficiency compared to D100 suggesting that ABE, an intermediate product during ABE fermentation, is a very promising alternative fuel to be directly used in diesel engines especially under LTC conditions. Meanwhile, ABE–diesel blends contain multiple components possessing drastically different volatilities, which greatly favor the occurrence of micro-explosion. This feature may result in better atomization and air–fuel mixing enhancement, which all contribute to the better combustion performance of ABE20 at LTC conditions.
Ultralow sulfur diesel (ULSD) fuel was blended with 5%, 10%, 15% and 20% of butanol by volume. The effects of these blended fuels on physicochemical characteristics of particulate emissions and the cytotoxicity of particulate extracts from a single cylinder, direct injection stationary diesel engine were investigated with the engine working at a constant speed of 3000 revolutions per min (rpm) and at 25%, 50% and 75% of its maximum output power. The results indicated a decrease in particulate mass and elemental carbon (EC) emissions, while an increase in the proportion of organic carbon (OC) in the particles with an increase in butanol in the fuel. Compared to the ULSD, the total number concentrations of volatile and non-volatile particles were reduced significantly for blended fuels, whereas the number of particles with diameter less than 15 nm increased for 15% and 20% butanol blends at low engine load. The increased total polycyclic aromatic hydrocarbons (PAHs) emissions, as well as their carcinogenic potency was also observed when the blends contained 15% and 20% butanol. In general, all the particle extracts showed a decline in cell viability with their increased dose and with the increased engine load while maintaining the same dose, based on the MTT assay.
This study presents the experimental results of surface tension measurements of diesel as well as canola, jatropha and soapnut biodiesel fuels. A high pressure pendant drop equipment (PD-E 1700) and drop shape analysis (DSA 100 V1.9) were used to measure the equilibrium surface tension of diesel and biodiesel fuels at elevated temperatures and pressures. Surface tension tests were carried out in a nitrogen environment. The surface tension of diesel and biodiesel fuels showed a linear relationship with temperatures and pressures. A regression model was also developed using the measured data from the tests for each fuel.
Butanol is a very competitive renewable biofuel for use in internal combustion engines given its many advantages. In this review, the properties of butanol are compared with the conventional gasoline, diesel fuel, and some widely used biofuels, i.e. methanol, ethanol, biodiesel. The comparison of fuel properties indicates that n-butanol has the potential to overcome the drawbacks brought by low-carbon alcohols or biodiesel. Then, the development of butanol production is reviewed and various methods for increasing fermentative butanol production are introduced in detailed, i.e. metabolic engineering of the Clostridia, advanced fermentation technique. The most costive part of the fermentation is the substrate, so methods involved in renewed substrates are also mentioned. Next, the applications of butanol as a biofuel are summarized from three aspects: (1) fundamental combustion experiments in some well-defined burning reactors; (2) a substitute for gasoline in spark ignition engine; (3) a substitute for diesel fuel in compression ignition engine. These studies demonstrate that butanol, as a potential second generation biofuel, is a better alternative for the gasoline or diesel fuel, from the viewpoints of combustion characteristics, engine performance, and exhaust emissions. However, butanol has not been intensively studied when compared to ethanol or biodiesel, for which considerable numbers of reports are available. Finally, some challenges and future research directions are outlined in the last section of this review.
Nitrogen oxides and smoke emissions are the most significant emissions for the diesel engines. Especially, fuels containing high-level oxygen content can have potential to reduce smoke emissions significantly. The aim of the present study is to evaluate the influence of n-butanol/diesel fuel blends (as an oxygenation additive for the diesel fuel) on engine performance and exhaust emissions in a small diesel engine. For this aim five-test fuels, B5 (contains 5% n-butanol and 95% diesel fuel in volume basis), B10, B15, B20 and neat diesel fuel, were prepared to test in a diesel engine. Tests were performed in a single cylinder, four stroke, unmodified, and naturally aspirated DI high speed diesel engine at constant engine speed (2600 rpm) and four different engine loads by using five-test fuels. The experimental test results showed that smoke opacity, nitrogen oxides, and carbon monoxide emissions reduced while hydrocarbon emissions increased with the increasing n-butanol content in the fuel blends. In addition, there is an increase in the brake specific fuel consumption and in the brake thermal efficiency with increasing n-butanol content in fuel blends. Also, exhaust gas temperature decreased with increasing n-butanol content in the fuel blends.Highlights► The DI diesel engine can run by using n-butanol/diesel fuel blends. ► Increasing n-butanol fraction in diesel fuel reduces the smoke, CO and NOX emissions. ► Also, the HC emissions shows increasing trend. ► The BSFC and the BTE increase with the increasing n-butanol fraction in diesel fuel.
To improve butanol selectivity, Clostridium acetobutylicum M5(pIMP1E1AB) was constructed by adhE1-ctfAB complementation of C. acetobutylicum M5, a derivative strain of C. acetobutylicum ATCC 824, which does not produce solvents due to the lack of megaplasmid pSOL1. The gene products of adhE1-ctfAB catalyze the formation of acetoacetate and ethanol/butanol with acid re-assimilation in solventogenesis. Effects of the adhE1-ctfAB complementation of M5 were studied by batch fermentations under various pH and glucose concentrations, and by flux balance analysis using a genome-scale metabolic model for this organism. The metabolically engineered M5(pIMP1E1AB) strain was able to produce 154 mM butanol with 9.9 mM acetone at pH 5.5, resulting in a butanol selectivity (a molar ratio of butanol to total solvents) of 0.84, which is much higher than that (0.57 at pH 5.0 or 0.61 at pH 5.5) of the wild-type strain ATCC 824. Unlike for C. acetobutylicum ATCC 824, a higher level of acetate accumulation was observed during fermentation of the M5 strain complemented with adhE1 and/or ctfAB. A plausible reason for this phenomenon is that the cellular metabolism was shifted towards acetate production to compensate reduced ATP production during the largely growth-associated butanol formation by the M5(pIMP1E1AB) strain.
A possible way to improve the economic efficacy of acetone-butanol-ethanol fermentation is to increase the butanol ratio by eliminating the production of other by-products, such as acetone. The acetoacetate decarboxylase gene (adc) in the hyperbutanol-producing industrial strain Clostridium acetobutylicum EA 2018 was disrupted using TargeTron technology. The butanol ratio increased from 70% to 80.05%, with acetone production reduced to approximately 0.21 g/L in the adc-disrupted mutant (2018adc). pH control was a critical factor in the improvement of cell growth and solvent production in strain 2018adc. The regulation of electron flow by the addition of methyl viologen altered the carbon flux from acetic acid production to butanol production in strain 2018adc, which resulted in an increased butanol ratio of 82% and a corresponding improvement in the overall yield of butanol from 57% to 70.8%. This study presents a general method of blocking acetone production by Clostridium and demonstrates the industrial potential of strain 2018adc.
The properties of gases and liquids
- B E Poling
- J M Prausnitz
- J P Oconnell