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The present study tested newly formulated hydrous ethanol–diesel‐emulsified fuel infused with nano‐sized γ‐Al2O3 particles on a turbocharged CRDI 4‐cylinder stationary diesel engine. W5H5, W5H10, and W10H5 test fuels were inducted into engine cylinders at a fixed engine speed of 2000 rpm. These test fuels significantly improved their physicochemical properties, with an 8.80% increase in gross calorific value and a 6.52% growth in cetane index. W5H10 exhibited a 16.01% increment in brake thermal efficiency and a 22.22% decrement in brake‐specific fuel consumption. Also, this fuel reported an 8.64% higher in‐cylinder pressure and a 40.71% higher heat release rate. W5H10 test fuel noted a 50% dip in carbon monoxide emissions and an 84.56% lower smoke opacity than diesel. W5H5 fuel reported 33.33% lower unburnt hydrocarbons than diesel at full load. W10H5 fuel observed an 88.46% drop in nitrogen oxide emissions compared with diesel at 10% engine load. The author found W5H10 the most suitable fuel for diesel engines with no modification costs. [ABSTRACT FROM AUTHOR]

The present experiment was conducted by executing detailed tests on performance, combustion, and emission characteristics to prove that the Nerium biodiesel emulsified fuel can be an eco-friendly fuel. The emulsified biodiesel was formed by mixing with a small proportion of water in the limits of 5%, 10%, and 15% by volume. This study also assessed the stability of different emulsified blends. The properties were tested according to ASTM requirements. The blend of 60% diesel, 20% biodiesel, 15% water, and 5% surfactant showed the higher brake thermal efficiency and in-cylinder pressure by 13.72% and 12.6%, respectively, when related to base fuel. Also, carbon monoxide, oxides of nitrogen, opacity of smoke and hydrocarbon emission of the above blend decreased by 42.87%, 6.5%, 12.96%, and 31.94%, respectively, when related to base fuel. This can be attributed due to the micro-explosion and availability of the oxygen content in the fuel. The results noticed a significant improvement and advantage of using the eco-friendly emulsified fuel in traditional engines without any modifications. Micro-explosion during combustion stage guaranteed a reduction in emission of nitrogen oxides (NOx). [ABSTRACT FROM AUTHOR]

Over the years, the diesel engine has been used in several marines, automobiles, locomotives, and agriculture applications due to its high efficiency and high-power torque capacity. However, the use of a diesel engine increases the rate of harmful pollutants like soot and NOx. This study aims to reduce engine emissions while simultaneously enhancing engine performance by using dual biodiesel emulsified fuel. For the preparation of the test fuel, a B20 Castor - Jatropha biodiesel blend (10% Castor + 10% Jatropha + 80% Diesel v/v %) was selected. Furthermore, for the preparation of emulsified test fuel, the concentration of water (0, 1, 2, 3, 4, 5 v/v %), surfactant (1, 2 v/v %) and HLB ratio (4.3, 5.3, 6) varies in the given range, respectively. During the experiment, parameters such as the stability of the fuel, engine performance, combustion, and emission analysis were carried out, comparing the test fuels with diesel. As the engine does not constantly operate at its full-rated load throughout its entire life, the results were therefore multiplied by the engine load factor. Our experiments demonstrated that the test fuel with a 5% water concentration formed the best-emulsified fuel. This fuel had a 14% higher BTE, 42% higher CO2, and ~60% lower NOx. Apart from this, the test fuel showed better combustion and performance characteristics than diesel and other emulsified fuels. The present work concludes that 20% of biodiesel, 2% surfactants, 5% water and 5.3 of HLB ratio shows reduced harmful engine emissions and improve engine performance.

When a diesel engine runs on water–fuel emulsion, carbon deposits break down on account of microimpact by the fuel droplets in the emulsion. The evaporation of the droplets depends on their diameter, the gas pressure, and the size of the bubble cavity. Removal of the deposits increases the mean compression ratio in the cylinder by 8% and the engine's power by 11%. Fuel consumption declines by 10%, and the smoke content of the exhaust gases declines by 16%. [ABSTRACT FROM AUTHOR]

Aligning to water-in-diesel emulsion technology, a newer work has been proposed in this study by introducing gomutra-in-diesel emulsion (GMD emulsion) fuel for application in CI engine. Experimental investigations have been performed in this study for ignition delay and combustion duration to understand the underlying mechanisms of combustion with this fuel. The complete work has been performed over a variable compression ratio (VCR) stationary diesel engine. Emulsions of different gomutra-in-diesel (5%, 10%, 15% and 20%) concentrations were taken for the study. The ignition delay was found to be 24°, 27°, 29°, 32°, and 34° crank angle (CA) with diesel, 5%, 10%, 15%, and 20% water-in-diesel emulsions respectively. The effect of injection timing on the engine performance was also analysed. It was observed that the combustion duration got decreased by a maximum of 12 degrees CA with 20% GMD emulsion. It is estimated that after the optimisation of other engine parameters like injection pressure and compression ratio, the performance of the engine could further be improved. [ABSTRACT FROM AUTHOR]

• High micro-explosion intensity induced by water nucleation favors the evaporation. • Diesel emulsified fuel has a better atomization effect. • FAME emulsified droplet shows a larger combustion rate. • Droplet diffusion combustion after premixed regime shows the sooty & jet flame. To address the problems of energy shortages and environmental pollution, biodiesel and its emulsified fuel have gained wide attention. In this work, the fatty acid methyl esters (FAME) emulsified water-in-oil fuel (BW) is thoroughly investigated using the droplet suspension experiment with a focus on the main characteristics of puffing/micro-explosion, droplet ignition delay and flame regime, etc. The role of water content at different ambient temperatures is examined in comparison to a counterpart blend of diesel/water (DW) fuel. Results show that the increase in water content and temperature has a significant promotion effect on the strength and number of puffing/micro-explosion process, however, the higher viscosity of BW leads to the lower values. And owing to the heat absorption by water evaporation, only the micro-explosion with high intensity induced by water nucleation has a favorable effect on the evaporation rate. There exists a critical concentration of water addition, after which the enhancement of evaporation is expected. Moreover, it is indicated that the diesel with water additives has a better atomization effect, and the size of child droplets generated by DW droplets breakup is smaller, which is in the range of 0.08–0.1 mm compared to the 0.09–0.13 mm for BW droplets. It has been shown that the increase in water content hinders the rise of droplet flame temperature, extends the ignition delay time, and shortens the maximum premixed-flame length. Compared to diesel droplets, the larger combustion rate of BW droplets is correlated with their shorter flame length and the higher boiling point of FAME. [ABSTRACT FROM AUTHOR]

The article presents the data regarding the experimental characterization of combustion of liquid jet A1 with addition of urea-water emulsion. A liquid-fuel gas turbine derived burner operating in non-premixed mode under three different equivalence fuel/air ratios was used. The data were collected, with and without urea addition, with two high speed visualization systems which acquired the broadband and spatially and spectrally resolved chemiluminescence emissions. Chemiluminescence images of OH* were acquired using an intensified camera system with a narrow-band filter at approximately 310 nm CWL, while the chemiluminescence images of CH* were recorded with a 436 nm CWL. Measurements of exhaust temperature and NOx, CO and CO2 emissions have been also performed. The data presented here are related to the article entitled “COMBUSTION PERFORMANCE OF A LOW NOx GAS TURBINE COMBUSTOR USING UREA ADDITION INTO LIQUID FUEL” [1].

• Enhancement in CI engine performance using Castor-Jatropha dual emulsified fuel. • Emulsified fuel is capable to reduce NOx by maximum up to 61% compared to diesel. • 5% water emulsified fuel provides approximately 14% more BTE compared to diesel. • Improvement in Ignition Delay (ID) with the help of emulsified fuel. • Dual biodiesel blended fuel is capable to reduce dependency on single biodiesel. • Emulsified fuel help in reducing EGT due to the micro explosion of water. Over the years, the diesel engine has been used in several marines, automobiles, locomotives, and agriculture applications due to its high efficiency and high-power torque capacity. However, the use of a diesel engine increases the rate of harmful pollutants like soot and NOx. This study aims to reduce engine emissions while simultaneously enhancing engine performance by using dual biodiesel emulsified fuel. For the preparation of the test fuel, a B20 Castor - Jatropha biodiesel blend (10% Castor + 10% Jatropha + 80% Diesel v/v %) was selected. Furthermore, for the preparation of emulsified test fuel, the concentration of water (0, 1, 2, 3, 4, 5 v/v %), surfactant (1, 2 v/v %) and HLB ratio (4.3, 5.3, 6) varies in the given range, respectively. During the experiment, parameters such as the stability of the fuel, engine performance, combustion, and emission analysis were carried out, comparing the test fuels with diesel. As the engine does not constantly operate at its full-rated load throughout its entire life, the results were therefore multiplied by the engine load factor. Our experiments demonstrated that the test fuel with a 5% water concentration formed the best-emulsified fuel. This fuel had a 14% higher BTE, 42% higher CO 2 , and ~60% lower NOx. Apart from this, the test fuel showed better combustion and performance characteristics than diesel and other emulsified fuels. The present work concludes that 20% of biodiesel, 2% surfactants, 5% water and 5.3 of HLB ratio shows reduced harmful engine emissions and improve engine performance. [ABSTRACT FROM AUTHOR]

• Small child droplets can be obtained by reducing the viscosity and surface tension. • The higher the viscosity and surface tension, the higher the breakup delay time. • The lower the interfacial tension, the higher number of heterogenic child droplets. • Micro-explosion delay time is minimum with the minimum emulsifier content. • The boundaries between breakup regimes depend of liquid and gas temperatures. Micro-explosion and puffing of multi-component slurry and emulsified fuel droplets can provide a several-fold increase in the evaporation and chemical reaction surface area. As a result, micro-explosion and puffing shorten the heating, evaporation, and ignition time of fuel compositions, improve the efficiency of their combustion, reduce fuel consumption, and provide its smooth spraying in combustion chambers. There are still no thorough studies on how the viscosity as well as surface and interfacial tension of emulsified fuels affect the integral characteristics of micro-explosive breakup of droplets under intense heating. In certain ranges of temperatures and component concentrations, there may be synergistic effects of these fuel characteristics on the threshold conditions and outcomes of micro-explosive droplet atomization. Such synergistic effects can make the secondary atomization of fuel droplets much more effective. In this research, we experimentally determine the heating times until breakup of relatively large emulsion droplets, the size and velocity distributions of newly formed child droplets with varying heating temperature, initial size of parent droplets, as well as component type and concentration. The results of this research are important for developing the current micro-explosion models and creating new, accounting for the breakup mechanisms and outcomes. [ABSTRACT FROM AUTHOR]

The characteristics of the emulsified fuel is largely influenced by the production methods of the emulsion. Although, blending by means of mechanical blender is widely used, the efficacy of using direct ultrasonic homogenizer in producing emulsified fuels has not been explored extensively. Mechanical blender uses metal blades to shear and mix the liquids and the produced emulsion quality would depend on the blade design, rotating speed and mixing duration. Hence, the homogeneity of emulsions produced by different blenders is not consistent. On the hand, ultrasonic homogenizer utilized direct ultrasonic force to produce high frequency vibrating waves to disrupt the immiscible liquid layers and mixed the liquids. Consistency and homogeneity of the emulsion produced by any direct ultrasonic homogenizer can be realized by changing the ultrasonic power, frequency and mixing duration. The current work describes the vital characteristics of water-in-biodiesel emulsions (WiBE) produced by direct ultrasonic homogenization and subsequently, ascertaining the optimum emulsion blends that meet the recommended international fuel specifications for a diesel engine. A total of 48 WiBE samples were prepared and their properties were characterized. The variable parameters for the blends are water content varying from 9% to 15%, three surfactant dosages of 5%, 7% and 9%, and hydrophilic-lipophilic balance (HLB) values ranging from 6 to 9. The results showed that the water particles in the emulsion were uniformly distributed within the continuous phase (biodiesel) and the sauter mean diameter (SMD) values of the water particles were generally small at a mean value of 2.25 µm. Emulsions with 7% and 9% surfactant dosages were observed to have lower SMD values for HLB 7 and HLB 8 respectively. 33 out of 48 samples were found to be stable emulsions. Emulsion with 11% water had the lowest mean density. The viscosity of all samples increased as water contents and surfactant dosages increase. Two samples were found to be the optimum WiBEs which are, 11% water content at HLB 7 with 9% surfactant dosage, and 11% water content at HLB 8 with 7% surfactant dosage. [ABSTRACT FROM AUTHOR]

The article discusses the possibility of using blended biofuels from rapeseed oil (RO) as fuel for a diesel engine. RO blended diesel fuel (DF) and emulsified multicomponent biofuels have been investigated. Fuel physicochemical properties have been analyzed. Experimental tests of a diesel engine D-245 in the operating conditions of the external characteristic curve and the 13-mode test cycle have been conducted to investigate the effect of these fuels on engine performances. CFD simulations of the nozzle inner flow were performed for DF and ethanol-emulsified RO. The possibility of a significant improvement in brake thermal efficiency of the engine has been noted. The efficiency of using blended biofuels from RO as a motor fuel for diesel engines has been evaluated based on the experimental test results. It was shown that in comparison with the presence of RO in emulsified multicomponent biofuel, the presence of water has a more significant effect on NOx emission reduction. The content of RO and the content of water in the investigated emulsified fuels have a comparable influence on exhaust smoke reduction. Nozzle inner flow simulations show that the emulsification of RO changes its flow behaviors and cavitation regime.

Abstract This paper deals with the evaporative characteristics and engine test results of emulsified fuels composed of diesel and hydrogen peroxide to reduce engine emissions by means of fuel design. The purpose of this study is basic research for applying emulsified fuel (EF) to engine through investigating the change of properties of emulsified fuel and the analysis of the behavior characteristics of free and impinging spray. In addition, the results are applied to real engine and the results of the study are presented comprehensively. To make the emulsified fuel for the experiment, the surfactant for mixing the emulsified fuel was fixed at a mixing ratio of 3% (vol.) of the total volume of the fuel, and Span 80 and Tween 80 were mixed at a ratio of 9:1. The mixing ratio of the hydrogen peroxide of the emulsified fuels was set to increase by 10% from EF2 to EF42 in consideration of the amount of the surfactant, and expressed as EF0 (diesel) in the case of diesel only. However, for the stable operation of the engine, the actual engine experiment was conducted only for the mixing ratios of EF0 and EF2. In order to analyze the characteristics of evaporation and engine emission reduction according to the mixing ratio of emulsified fuel, the experiments of droplet, free spray, impinging spray and actual engine were performed, respectively. Experimental images for visualization were obtained by using scattered light and Schlieren method. In the case of the droplet experiment, the evaporation characteristics were analyzed by free drop of the fuel droplet on a heating plate maintained at 473 K. The injection pressures of the emulsified fuel were set to 40 MPa, 60 MPa, 80 MPa and 100 MPa. In the case of free spray, experiment was carried out in a constant volume chamber maintained at room temperature (288 K) and 423 K. In the case of the impinging spray, the temperature of the impinged plate was changed to 423 K, 473 K and 523 K, respectively. The evaporation characteristics of the emulsified fuel were analyzed through the analysis of the fuel diffusion area and the entropy analysis based on statistical thermodynamics using the results obtained from such experiments. It was found that droplet and spray evaporation were promoted as the mixing of hydrogen peroxide in the emulsified fuel increased, and a method of quantitatively analyzing the experimental phenomenon could be proposed. From these results, it can be expected that the mixture of emulsified fuel mixed with hydrogen peroxide can be formed faster than the conventional diesel when applied to a real diesel engine. As a result, it is expected to play a positive role in terms of engine emission reduction. Based on these basic experimental results, emulsified fuels with mixing ratios of EF0 and EF2 were applied to diesel engine and actual engine test was conducted. NOx and soot were reduced by rapid mixture formation due to the fuel evaporation promoting effect as well as the effect of lowering the temperature of the combustion chamber due to the latent heat of evaporation of the hydrogen peroxide contained in the emulsified fuel. Finally, it can be confirmed that when the proper mixture ratio of emulsified fuel is selected for main engine operation, simultaneous reduction of NOx and soot is possible. [ABSTRACT FROM AUTHOR]

This study compiled the results of various researches performed on using nanomaterials additives in diesel engine fuels such as diesel, biodiesel, water emulsified fuels and various fuel blends. Three different techniques are used the reduction of the harmful exhaust emissions of the diesel engine. The first technique for the reduction of harmful emissions is improved the combustion by modification of engine design and fuel injection system, but this process is expensive and time consuming. The second technique is the using various exhaust gas devices like catalytic converter and diesel particulate filter. However, the use of these devices affects negatively diesel engine performance. The other technique to reduce emissions and also improve diesel engine performance is the use of various fuel additives. The major pollutants of diesel engine are oxide of nitrogen (NOx) and particulate matter (PM). It is very difficult to reduce NOx and PM simultaneously in practice. The most researches declare that the best way to reduce the emissions and increase the engine performance is the use of nano material additives and water emulsified fuels. The effects on fuel properties and combustion characteristics of different nano material additives in various diesel engine fuels are investigated in this review. [ABSTRACT FROM AUTHOR]

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• Automative Compression Ignition Engine Powered by Cerium Oxide Nanoparticles Doped Water Diesel Emulsion Fuel. • To explore the performance of internal combustion engines by combining diesel, biodiesel, water, and nanoparticles. • Water emulsion blended fuel with nanoparticles addition in diesel engine. • Diesel engine was studied using the produced blended fuel. • The NOx discharge sizes for diesel, E 15 , E 15 CeO 240 , E 15 CeO 260 , and E 15 CeO 280 , respectively. The rising consumption of oil and air pollution in developing countries compelled us to seek suitable alternative fuels for the existing compression ignition engines used in power generation, transportation, and industrial sectors, all of which play a strong role in the development of the nation's economy. Moreover, rising demand and consumption also causes a huge impact on our economy as we are dependent on other nations to cater to our needs as domestic production fails to fulfill the present requirement and leads to huge import bills that affect the ordinary man. A water/diesel (W/D) emulsified formulation helps to diminish the engine exhaust discharge without compromising the engine's performance. The current task experimentally evaluates the execution and discharge characteristics of cerium oxide nano-particles doped water diesel emulsion fuel viz E 15 , E 15 CeO 2 (40), E 15 CeO 2 (60), and E 15 CeO 2 (80) on multi-cylinder automotive compression ignition engine at steady 1650 rpm, under variable test load situation. Mechanical stirring was used to make E 15 water diesel emulsion fuel, whereas ultrasonicator and mechanical stirrer were used to make E 15 CeO 2 (40), E 15 CeO 2 (60), and E 15 CeO 2 (80) blends. Surfactants span 80 and tween 80 were used. The concentrations of cerium oxide nanoparticles in emulsion fuel samples were 40, 60, and 80 ppm, respectively. The characteristics like thickness, flash point, and heating value of test fuels were evaluated and reported within the range as specified by governing standards. The execution and discharge characteristics of various emulsion fuel samples were compared to standard diesel. At maximum load, cerium oxide doped fuels greatly improve engine performance while lowering environmentally harmful engine pollutants such smoke opacity, NOx, carbon monoxide, and hydrocarbon emissions by 40.27%, 33.60%, 30%, and 18.75%, respectively. [ABSTRACT FROM AUTHOR]

The present study is aimed to analyze the combustion, performance, and emission characteristics of water-emulsified soybean biodiesel fueled diesel engine with alumina nanoadditive and the results compared with conventional diesel fuel (BD). Experiments were conducted in a single-cylinder, four-stroke, variable compression ratio, and natural aspirated diesel engine with an eddy current dynamometer at a constant speed of 1500 rpm. Water-soybean biodiesel emulsion fuel was prepared using a mechanical agitator, in which the water concentration was limited to 10%, whereas soybean biodiesel (SB) and surfactant concentrations were 89% and 1% by volume respectively. Alumina (Al) was chosen as a nanoadditive, and the mass fractions of 50 ppm and 100 ppm were blended with emulsion fuel using ultrasonicator and the physicochemical properties were measured. The physicochemical properties of water-emulsified biodiesel and nanoadditive included emulsified biodiesel are at par with EN14214 limits. The in-cylinder pressure (ICP) and net heat release rate (NHR) values of SB are 5.3% and 7.2% lower than BD respectively, whereas the water inclusion significantly increases the ICP and NHR values by 6.9% and 15.9% compared to SB. Brake-specific fuel consumption (BSFC) of SB is higher than BD, and brake-specific energy consumption (BSEC) is lower than BD. An inclusion of 10% water in SB improves the BSFC and BSEC by 4% and 10.6% respectively compared to SB. The Al nanoparticle inclusion in water-emulsified soybean biodiesel further improves the combustion and performance parameters. The exhaust gas temperature (EGT) of sample fuels seems to be lesser than BD due to efficient combustion. As far as the emission characteristics are concerned, the SB promotes lower level of hydrocarbon (HC), carbon monoxide (CO), and smoke emissions with notable increases in oxides of nitrogen (NOx) and carbon dioxide (CO2) emissions. An inclusion of 10% water in SB reduces the NOx, HC, CO, and smoke emission by 21.2%, 16.7%, 16.9%, and 11.8% respectively under peak brake mean effective pressure (BMEP) condition. The addition of Al nanoparticle in biodiesel emulsion fuel further reduce NOx, HC, CO, and smoke emissions and marginally increases the CO2 emission. [ABSTRACT FROM AUTHOR]

This study compiled the results of various researches performed on using nanomaterials additives in diesel engine fuels such as diesel, biodiesel, water emulsified fuels and various fuel blends. Three different techniques are used the reduction of the harmful exhaust emissions of the diesel engine. The first technique for the reduction of harmful emissions is improved the combustion by modification of engine design and fuel injection system, but this process is expensive and time consuming. The second technique is the using various exhaust gas devices like catalytic converter and diesel particulate filter. However, the use of these devices affects negatively diesel engine performance. The other technique to reduce emissions and also improve diesel engine performance is the use of various fuel additives. The major pollutants of diesel engine are oxide of nitrogen (NOx) and particulate matter (PM). It is very difficult to reduce NOx and PM simultaneously in practice. The most researches declare that the best way to reduce the emissions and increase the engine performance is the use of nano material additives and water emulsified fuels. The effects on fuel properties and combustion characteristics of different nano material additives in various diesel engine fuels are investigated in this review. [ABSTRACT FROM AUTHOR]

This study is a basic research on the application of the mixed emulsified fuel of diesel and hydrogen peroxide (H2O2) to the diesel engine and investigating the evaporative characteristics of the emulsified fuel. The surfactant used to mix the emulsified fuel was added by mixing the span 80 and tween 80 with a ratio of 9:1 and being fixed to 3 % of the total volume of the emulsified fuel. The mixing ratio of the emulsified fuel was selected as EF0 (Only diesel), EF2, EF12, EF22, EF32 and EF42, respectively, considering the mixing ratio of the surfactant. To analyze the evaporative characteristics of the emulsified fuel in accordance with the mixing ratio, a drop of the emulsified fuel was freely dropped to a hot plate maintained at 473 K with a spuit and then the experimental results of the drop evaporation were visualized with the Schlieren system. Then, the quantitative image analysis of the images was introduced and it could be found that droplet evaporation was promoted according to the increase of the hydrogen peroxide in the emulsified fuel. Also, numerical analysis was performed with modeling for micro droplets in the fuel based on the experimental result, and promoted-fuel evaporation was reproduced due to the microexplosion of evaporative characteristics of emulsified fuel in accordance with the increase of the mixing ratio of hydrogen peroxide. Also, for quantitative analysis of experimental results, entropy analysis based on statistical thermodynamics was carried out. Consequently, in the case of the application of emulsified fuel to the diesel engine, it is expected to simultaneously decrease the Soot and NOx generation by speedily mixture formation and the latent heat of evaporation of the emulsified fuel in the cylinder. [ABSTRACT FROM AUTHOR]

The emulsified behaviors in the process of preparing methanol-diesel emulsified fuel are investigated by the application of an impinging stream-rotating packed bed (IS-RPB). The emulsified processes are composed of the combinations of initial emulsification of impinging stream process, intensified emulsification of IS-RPB and perfect emulsification of back-splashing and atomization to complete the entire emulsified process through the analysis of force posed on all fluid particles in IS-RPB. The existence of the three emulsified processes is proved using the computational fluid dynamics (CFD) simulations. The turbulent kinetic energy and velocity vector of the three emulsified processes using the CFD simulations were analyzed logically, which proved the existence of the three emulsified processes. Based on the analysis and CFD simulations, the properties of stabilization, dispersion, micro-mixing and power consumption performance were compared under the IS-RPB and high speed stirrer, which further prove the practicability and advancement of this technology for methanol-diesel emulsified fuel. [ABSTRACT FROM AUTHOR]

• A theoretical model for microexplosion and puffing in droplets is proposed. • Microexplosion of n -dodecane/water droplets is analyzed. • Multiple bubbles are considered inside a droplet. • t e diminish by 40% for 10-times rise in initial bubble diameter. • t e attain asymptotic value with >15 bubbles. This paper presents a theoretical model for microexplosion and puffing in a single isolated emulsion droplet at high ambient temperature and one atmospheric pressure. The model considered transient heating of the droplet, bubble growth dynamics, bubble motion, and bubble interactions (e.g., bubble coalescence). The bubble growth is determined by solving a modified Rayleigh equation which considered bubble interactions. The model considered multiple bubbles inside a fuel droplet which were not accounted for in the models proposed in previous studies. The model is applied to simulating the microexplosion of n -dodecane/water droplets. The simulated microexplosion delay times are compared with the experimental data from the literature, with good qualitative and quantitative agreements obtained. Results show that microexplosion delay time diminished by 40% and 50% for a 10-times increase in the initial bubble diameter and changing the bubble location from droplet center to 0.4 times the droplet radius, respectively. For multiple bubbles inside the droplet, the microexplosion delay time converges to a minimum threshold value without further changing the bubble number. The simplified model bears practical potential in enabling spray combustion modeling of water-emulsified fuels with considerably reduced computational costs. [ABSTRACT FROM AUTHOR]

Diminishing fuel resources and stringent emission mandates have demanded cleaner combustion and increased fuel efficiency. Three water addition rates, i.e., 2, 4, and 6 wt% in biodiesel-diesel blend (B5) was investigated herein. Combustion characteristics of the emulsified fuel blends were compared in a naturally-aspirated diesel engine at full load and different engine speeds. More specifically, biodiesel was produced from waste cooking oil (WCO) and to further increase waste utilization, recycled biodiesel wastewater was used as additive in B5. The result obtained showed that low-level water addition (i.e., 2 and 4 wt%) in B5 led to different results from those obtained using higher water addition rates (i.e., >5 wt%) reported by the previous studies. In more details, the findings of the present study revealed that low level water addition in B5 could considerably reduce CO, HC, CO 2 , and NO x emissions. Among water-containing B5 fuel emulsions, the optimal water addition level in terms of engine performance parameters and emissions was found at 4 wt%. In particular, the emitted CO 2 , HC, and NO x were decreased by over 8.5%, 28%, and 24%, respectively, at maximum speed of 2500 rpm. [ABSTRACT FROM AUTHOR]

The micro-explosion of emulsion droplets plays an important role in promoting atomization, improving combustion efficiency, and reducing pollutant emissions. In this experimental study of the micro-explosion of emulsion droplets, we find that mist can be generated during the heating of emulsion droplets, and the mist generation is closely related to the micro-explosion process. Combined analysis from high-speed images, gas chromatography, and droplet temperature variation shows that the mist generation is due to the condensation of vapor into small droplets as the temperature decreases. Two micro-explosion modes are observed, intense micro-explosion with a large amount of mist and weak micro-explosion with a small amount of mist. Different emulsified fuels are tested, and mist can be produced for all the emulsified fuels. The mist is quantitatively analyzed via digital image processing. According to the mist concentration curve in the micro-explosion process, the micro-explosion mode can be distinguished. The effects of the water and surfactant contents in the emulsion droplets are studied, and the mists are used to characterize the micro-explosion. Increasing the water content can promote the vaporization of the water phase, increase the strength of micro-explosion, and result in a large amount of mist. Increasing the surfactant content can improve the stability of the emulsion droplet, reduce the probability of intense micro-explosion, and hence reduce the mist concentration. [Display omitted] • Mist can be generated during the micro-explosion/puffing of heated emulsion droplets. • Mist generation is due to the sudden condensation of vapor into many small droplets. • Micro-explosion mode can be distinguished according to the mist concentration curve. • Increasing water content can increase water vaporization and promote mist generation. • Increasing surfactant content can stabilize the emulsion and reduce mist generation. [ABSTRACT FROM AUTHOR]

In this study, secondary atomization of emulsified fuel spray was visualized, and the effect of ambient temperature on secondary atomization in spray flow was investigated. The W/O emulsified fuel was prepared by adding 10 wt% water and 0.75 wt% emulsifying agent (sorbitan monooleate) to n-dodecane. A shadow imaging system consisting of high-speed video camera (125,000 fps) and metal halide lamp was used to visualize secondary atomization of spray droplets. As a result, it clearly showed that secondary atomization of spray droplet was caused by vapor production inside the spray droplet due to the rapid evaporation of dispersed water. When the furnace wall temperature (Tw) was 823 K, there is no significant difference between the size distribution of emulsified fuel spray and that of n-dodecane spray because the droplet temperature was too low to produce vapor inside the spray droplet, leading to decreasing secondary atomization effect. Meanwhile, at Tw = 923 K and 973 K, the size distribution of emulsified fuel spray droplets was shifted to smaller than that of n-dodecane spray droplets. This is because the droplet temperature was enough to produce vapor inside the droplet and secondary atomization was enhanced. It was indicated that ambient temperature was important in the occurrence of secondary atomization.

This research paper reports the results of various researches carried out up to 2015 on the performance and emission characteristics of compression ignition (CI) engine using nano particles additives in diesel, biodiesel and water emulsified fuels. There are two methods of reducing the exhaust gas emission of the CI engine. First method is to reduce the emissions by using exhaust gas treatment devices like catalytic converter, diesel particulate filter. However, use of these devices affects the performance of CI engine. Second method to reduce emissions and improve performance of CI engine is the use of fuel additive. Main pollutants of CI engine are oxide of nitrogen (NO x ) and particulate matter (PM). However, it is difficult to control NO x and PM simultaneously. Many researchers report that the best method to control the emissions and improve the performance is the use of nano particles additives and water emulsified fuels. This research paper also reports the biodiesel fuel as an alternative to diesel fuel by using various nano particle additives. Comparative studies of effects on various properties of diesel and biodiesel fuels without/with water contents and nano particles additives by previous researchers are done. Most of the researchers reported improved performance and reduction in emission characteristics with dosing of nano particles additives in diesel and biodiesel. [ABSTRACT FROM AUTHOR]

The present study is an attempt to estimate the energy and the exergy potential of a biogas run dual fuel diesel engine using emulsified rice bran biodiesel (RBB) as pilot fuel at varying compression ratio (CR) and injection timing (IT). The objective is to arrive at an optimum setting of the engine based on dual fuel characteristics using energy and exergy analysis. The pilot fuel considered for this study is a two-phase stable water emulsion of RBB having water content (5%), surfactants (3%), and hydrophilic lipophilic balance value of 6. For experimentation, a 3.5 kW single cylinder, direct injection (Dl), natural aspirated water-cooled, variable CR (VCR) diesel engine is converted into a dual fuel engine. Experiments are conducted for 12 different combinations of CR of 18, 17.5, and 17 and IT of 23 deg, 26 deg, 29 deg, and 32 deg bottom top dead center (BTDC) at full load conditions of brake mean effective pressure (BMEP) of 4.24 bar. The parameters analyzed are the energy and exergy potential of fuel input, shaft work, cooling water, exhaust gas, exergy destruction, peak cylinder pressure (PCP), peak heat release rate (PHRR), brake thermal efficiency (BTE), exergy efficiency, exhaust gas temperature (EGT), entropy generation rate, and emission analysis. The results indicate that the combination of CR = 18 and IT = 29 deg BTDC gives a better thermodynamic performance for this particular range of the operating parameters for a raw biogas run dual fuel diesel engine using emulsified RBB as pilot fuel. [ABSTRACT FROM AUTHOR]

A new continuous process for preparing methanol–diesel oil emulsified fuel is proposed using an impinging stream–rotating packed bed. The combustion of methanol–diesel oil emulsified fuel is significantly affected by its stability. Thus, the stabilization of the methanol–diesel oil emulsified fuel was investigated by varying numerous factors, including high-gravity factor, impinging distance, hydrophilic-lipophilic balance value, liquid flow rate, co-surfactants, content of methanol and emulsifier, and so on. The stabilized time and size of dispersed phase of methanol-diesel oil emulsified fuel were 762 h and 12 μm separately at the operating conditions of liquid flow rate of 70 L/h, an impinging distance of 30 mm, a hydrophilic–lipophilic balance value of 5.4, a high gravity factor of 208.1, a methanol volume content of 15%, co-surfactants of 1-butanol, an emulsifier amount of 3%, and consecutive recycle time of 3. The proposed technology can be applied in industries because of the use of relatively less emulsifier as well as its continuity, processing efficiency, and ease of application in large-scale production. [ABSTRACT FROM AUTHOR]