Emulsion Fuels Research Articles

Evaporation of stable microemulsion droplets

Emulsion fuels have the potential to reduce both particulate matter and NOx emissions and can potentially improve the efficiency of combustion engines. However, their limited stability remains a critical barrier to practical use as an alternative fuel. In this study, we explore the evaporation behavior of thermodynamically stable water-in-oil microemulsions. The water-in-oil microemulsion droplets prepared from different types of oil were acoustically levitated and heated using a continuous laser at different irradiation intensities. We show that the evaporation characteristics of these microemulsions can be controlled by varying water-to-surfactant molar ratio (ω) and volume fraction of the dispersed phase (ϕ). The emulsion droplets undergo three distinct stages of evaporation, namely preheating, steady evaporation, and unsteady evaporation. During the steady evaporation phase, increasing ϕ reduces the evaporation rate for a fixed ω. It is observed that the evaporation of microemulsion is governed by the complex interplay between its constituents and their properties. We propose a parameter (η) denoting the volume fraction ratio between volatile and nonvolatile components, which indicates the cumulative influence of various factors affecting the evaporation process. The evaporation of microemulsions eventually leads to the formation of solid spherical shells, which may undergo buckling. The distinction in the morphology of these shells is explored in detail using scanning electron microscopy imaging.

The Impact of Varying Mixing Rates in a Surfactant-Free Fuel Emulsion Mixer on the Efficiency and Emissions of a Diesel Engine

The research focuses on water diesel emulsion (WDE), a topic that has captivated researchers for an extended period. While previous studies predominantly employed surfactants to enhance mixing efficiency, their non-economic feasibility in transportation logistics has prompted a shift in recent investigations. This study presents experiments utilizing a cost-effective WDE comprising 15% water and a mixer devoid of surfactants to investigate the impact of mixer blade rotation on engine performance, fuel consumption, and NOx emissions. NOx emission tests were conducted under a constant engine speed of 2,000 rpm and a 75% load (3,23 kW). The optimal brake-specific fuel consumption (BSFC) for the 15% WDE fuel occurred at a blade rotation speed of 3,000 rpm, resulting in a 1% power reduction (from 4,41 kW to 4,38 kW), a 13.3% decrease in BSFC (from 694,98 gr/kW.h to 602,52 gr/kW.h), and a 30% reduction in NOx emissions (from 54 ppm to 38 ppm). This discovery holds promise for future advancements in green energy applications within the transportation sector.

Performance and Emission of Non-surfactant Water-in-Diesel Emulsion Fuel Using Light-Duty Trucks on Urban Road Conditions

Performance and Emission of Non-surfactant Water-in-Diesel Emulsion Fuel Using Light-Duty Trucks on Urban Road Conditions

An experimental study and ANN analysis of utilizing ammonia as a hydrogen carrier by real-time emulsion fuel injection to promote cleaner combustion

This work utilized Real-Time Emulsion Fuel Injection (RTEFI) methods to incorporate emulsion fuel, which included citronella oil (20%), ammonia (10%), and water (5%), into diesel fuel without the addition of surfactants. The primary aim of this study was to investigate the influence of hydrogen presence in liquid ammonia on diesel engines. This was accomplished by using a water-emulsified diesel-biodiesel blend and forecasting performance using an artificial neural network (ANN). Citronella oil (20%) was blended with standard fuel (SD), followed by the addition of 10% ammonia and 5% water, labeled as SD20CO, SD20CO10A, and SD20CO10A5W, respectively. The results indicated that the brake thermal efficiency of SD20CO10A5W is comparable to that of diesel. The fuel combination significantly decreased hydrocarbon emissions by 70–75%, smoke by 10–15%, and oxides of nitrogen by 2–5%, while increasing carbon dioxide by 3–8% under all load situations compared to other fuels. The trained ANN models had a coefficient of determination of 97%, with values ranging from 0.9076 to 0.9965. Additionally, the models exhibited low mean absolute percentage error values, ranging from 0.98% to 4.26%. The analytical results provide strong evidence supporting the efficacy of SD20CO10A5W, ultimately indicating that it is a feasible substitute fuel for diesel engines.

Emulsions as Viable Alternative to Conventional Fuels: Current Status and Challenges.

The scientific investigation of water-in-fuel emulsions spans over five decades; however, the widespread implementation of emulsion fuels in commercial settings has proven to be a challenging endeavor. This Perspective discusses the current status of the research pertaining to the formation and stability of emulsion fuels, technical and regulatory challenges, and opportunities. In particular, we highlight the need for a coordinated effort between the colloid and interface community and those actively investigating emissions, spray characteristics, and combustion aspects in internal combustion engines.

STUDY OF MODIFIED BIO-NANO DIESEL EMULSION FUELS TO SAVE ENERGY, REDUCE POLLUTION, AND IMPROVE DIESEL ENGINE PERFORMANCE

The world is currently facing an energy challenge. Even though nanotechnology has the potential to significantly advance a wide range of disciplines, there are concerns about the potential hazards of its products and uses. The primary cause for concern is nanoparticle toxicity and its possible absorption into the body. Because metallic and metal oxide nanoparticles can have harmful impacts on living beings, the introduction of biocompatible nanoparticles can considerably reduce these problems. In this investigation, a modified bio-nano diesel emulsion fuel is presented that saves energy, reduces pollution, and enhances diesel engine performance. The biodegradable carbon quantum dots (CQDs) were synthesized from mosambi peels via a catalytic technique and then extensively examined. Experiments were performed on single-cylinder water-cooled engines with varying loads, compression ratios, and engine speeds. Water and CQDs were introduced into B20 at successive levels of integration of 3%, 5%, 10%, and 25 ppm, 50 ppm, and 75 ppm, respectively. The highest reduction in NO<sub>x</sub> was attained with blended fuel containing 75 ppm of CQDs and 10% water content, which was around 158% more effective than diesel but only about 115% more effective than non-CQDs biodiesel. The greatest improvement in brake thermal efficiency was observed for the fuel sample containing 5% water and 75 ppm CQDs, nearly 154% compared to the biodiesel blend, but approximately 135% compared to diesel.

Influence of surfactant addition to emulsion fuels on the hot section of turbine engines

Due to the growing awareness of ecological threats, more and more attention is paid to the emission problem of undesirable substances into the atmosphere, the source of which is transport and energy. The impact of these factors on the environment can be reduced by using alternative fuels, which are non-fossil fuels, or by modifying these fuels to ensure lower emissions. One of the methods for reducing emissions from engines is the use of water fuel emulsion as fuel, which has a particularly positive effect on the emission of nitrogen oxides at high loads of drive and power units. An important issue affecting the possibility of using this fuel type is the impact of their use on the elements of the units in contact with fuel containing water and, optionally, an emulsifier. This paper presents inspection results of the hot section of a miniature gas turbine powered by Jet-A1 aviation fuel with the emulsifier addition. On the basis of these observations, the components of emulsion fuels were determined, which are the cause of the characteristic deposits occurring on the hot sections of the units after using emulsion fuels.

Experimental stability investigation of different water-in-jojoba biodiesel emulsions

Investigating the stability of water in biodiesel emulsion fuels during storage and engine operation is crucial to consider for marketing processes. This study examines the stability of water-in-Jojoba biodiesel (WJBD) emulsion that is stabilized using three commercially available surfactants, Span-80 (HLB 4.3), Tween-80 (HLB 15), Triton X-100 (HLB 13.5). The investigation involves varying the composition of the emulsions by adjusting factors such as the hydrophile lipophile balance (HLB), surfactant concentration, water concentration, mixing speed, and mixing duration, and study their effects through a bottle test. Stable emulsions are studied by bright field optical microscopy, constant shear test, and thermal loop rheology test. The research reveals that Tween-80 (HLB 15) and Span-80 (HLB 4.3) effectively yield emulsions with high relative stability. Specifically, at 5 (v%) water concentration, emulsions prepared with Tween-80 (HLB 15) demonstrate the formation of water droplets as small as 3.88 µm. Additionally, emulsions at various water concentrations are thoroughly studied. Over time, phase separation is studied by microscopic images and showed minimal coalescence after the first day for the emulsions that showed promising stability in the bottle test. To further assess the stability, the stable emulsions undergo continuous shear test, wherein a consistent pattern of stable viscosity is observed as time passed. Moreover, the thermal loop test showed minimal change in the relative microstructure of the emulsion, where the difference in the storage modulus and the loss modulus didn’t exceed 15 % and 5 %, respectively. Understanding the change in microstructure, droplet sizes, and how the emulsions behave under certain shear stresses is critical for practical applications of this fuel. Through comprehending the factors that influence the emulsion stability, this study contributes valuable insights for the successful storage and engine operation of the WJBD.

Implementation of a Non-Surfactant Water-in-Diesel Emulsion Fuel in a Common Rail Direct Injection Diesel Vehicle

Implementation of a Non-Surfactant Water-in-Diesel Emulsion Fuel in a Common Rail Direct Injection Diesel Vehicle

Performance Analysis of Compression Ignition Engines Using Emulsion Fuel Blended with Aluminium Oxide Nanoparticles

One of the excellent choices for compression ignition engines is emulsions. The current experimental analysis deals with transesterified Pongamia biodiesel. This work gives a substantial track to synthesize and to enhance fuel by including aluminium oxide nanoparticles. Emulsification is used to prepare fuel consisting of 88% of Pongamia biodiesel, 10% water, and 2% surfactants with series chemical emulsification techniques. This is then mixed with the ratio of 50 ppm and 100 ppm by mass with aluminium oxide nanoparticles by employing ultrasonication techniques. This work is carried out on compression ignition engines in different phases using biodiesel, nanoparticles, surfactants, and water. It was inferred from the results that there was a considerable enhancement in performance and decrease in emission when compared with diesel. It is found that the system exhibited 15% improvement in brake thermal efficiency and 45% reduction in oxides of nitrogen. The system exhibited considerable improvement in performance and reduction in emission.

Analysis of compositions and fuel specifications of the aqueous emulsion fuels of gasoline (RON 90)-ethanol-water in stable emulsions at low temperatures

Many countries worldwide encounter the greatest difficulties in improving people's life quality since fossil fuel reserves are decreasing, causing fuel prices to rise drastically. This problem has made many countries, including Indonesia, struggle to import them from producers in the Middle East. Adding a small part of ethanol to gasoline is one of the solutions that has been investigated and developed. The previous works relating to blended fuels, gasoline and ethanol, generally employed absolute alcohol, which was expensive. A small surfactant was added to the mixture to stabilize the emulsion, and the blending was conducted in normal conditions (room temperature). If the composition of gasoline and aqueous ethanol is not precise, the components can be separated at a specific temperature. The present study is aimed to report the analysis of compositions and fuel specifications of aqueous emulsions of gasoline (RON 90)-ethanol-water in a single phase without using a synthetic surfactant in the temperature range of 0–25 °C. The procedures were as follows: fermentation, ethanol distillation and purification, cooling, blending, and characterization of fuel specifications. Components of gasoline (RON 90)-ethanol-water formed a stable emulsion in the composition range of 28.00‒99.79 %, 0.20‒67.97 %, and 0.01‒3.58 %. The observation found that continually increasing the amount of aqueous ethanol and temperature after one phase was attained would not lead to the separation of components. Therefore, gasoline and aqueous ethanol can form a single phase functioning as a surfactant binding water and fossil fuel. The decrease in temperature after the emulsion is stabilized can separate the components whereby it is caused by the faster density change of aqueous ethanol than gasoline

Unveiling the status of emulsified water-in-diesel and nanoparticles on diesel engine attributes

Due to the obvious increase in the environmental and human health concerns produced by diesel engines, there has been a lot of interest in ecologically friendly diesel fuels. Current research and development efforts are focused on water-in-diesel emulsion (WiDE) fuels, which have the potential to reduce nitrogen oxide (NOx) and particulate matter (PM) emissions while enhancing performance and allowing for more efficient energy development in a cleaner environment using existing diesel engines. The current topic is concerned with the WiDE fuel principle, emulsification stability, physio-chemical attributes, latest trends in emulsion fuel, the impact of WiDE fuel on engine attributes and the barriers to commercialization of emulsified fuel. Furthermore, the importance of nanoparticle additives in WiDE, nano-fuel formulation, and their impact on engine attributes are explored.

Atomization characteristics of different water/heavy fuel oil emulsions in a pressure-swirl injector

In the present study, different water in heavy fuel oil (HFO) emulsion fuels containing 5, 10, 15% water content have been prepared under ultrasound irradiation without surfactant. The stability of the prepared emulsion fuels has been investigated. The best stability was observed for the emulsion fuel containing 5% water (E5) due to its more uniform water droplet size distribution. Then, the atomization behavior and spray characteristics of the emulsion fuels have been investigated in a pressure-swirl injector using a high speed camera. The examined ranges for temperature and pressure were (60–110 °C), and (10–25 bar), respectively. The breakup length for each fuel sample in each operating condition was calculated through the image processing analysis. It was found that the micro explosion phenomena associated with the evaporation of the water droplets in the fuels has the most impact on the emulsion fuel spray characteristics. The best atomization performance was observed for E5 considering all examined fuel samples. A 68% decrease in the breakup length was observed for E5 compared to the neat HFO at 90 °C and 15 bar.

The effect of different in-line mixers producing emulsifier-free bio-diesel emulsion on the diesel engine combustion performance and exhaust emission

The energy crisis that the world facing right now causes researchers all over the world to opt for alternative fuels. Alternative fuels such as water in diesel emulsion gained attention in various studies due to their performance and capability in reducing harmful emissions such as NOx and PM. A new concept was introduced to make water in diesel emulsion without using a surfactant through a device called Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES) and directly supply the fuel to the engine. This real-time emulsification concept requires a strong mixer, however, it consumes high energy. Thus, this study focused on the effect of different in-line mixers producing emulsifier-free bio-diesel emulsions on stability, diesel engine combustion, performance, and exhaust emission. The original RTES consists of a high shear mixer and ultrasonic mixer, while a new parameter for RTES (RTES-SM) is the high shear mixer and static mixer. The effect of the different inline mixers of RTES and RTES-SM was tested on the stability testing, engine dynamometer under various loading of 2 kW, 4 kW, and 6 kW, and real vehicle testing. The water percentage was set in the range of 7–10 %. Overall, the RTES showed better results on stability and engine dynamometer, but on real vehicle testing, the result is comparable to RTES-SM. Thus, this new concept of an inline mixing system of non-surfactant biodiesel emulsion (RTES-SM) showed better energy efficiency, promising results in real vehicle testing, and potential options in emulsion mixing technologies.

Storage and Temperature Stability of Emulsified Biodiesel-Diesel Blends.

The scarcity of fossil fuel has led to the recent worldwide commercialization of biodiesel-blended diesel. The benefits associated with emulsion fuels have encouraged researchers to study the blended emulsified fuels in diesel engines. Recent results show the effectiveness of blended emulsified fuels in terms of better fuel economy and less harmful emissions. Investigation on the stability of these blended emulsified fuels during storage in the fuel tank is equally crucial for commercialization and practical application. A systematic study on the storage stability of water in biodiesel/diesel blend nanoemulsions (nEs) is presented in this work. A mixture of two biodegradable surfactants, Span 80 and Tween 80, is used to stabilize the nEs. The nEs are formulated by subjecting a mixture of 5 vol % of each surfactant, 5 vol % of water, and 85 vol % of pure or blended diesel to high shear homogenization at 5000 rpm for 2 min. Storage stability of the emulsified fuels is studied for 65 days at 25 °C with the help of dynamic light scattering and viscosity measurements. The mean droplet size increases, and the stability decreases with an increase in the biodiesel concentration. The smallest mean droplet size is 32 nm for emulsified fuel using pure diesel, and these emulsions remain stable for 65 days. No macroscopic phase separation is observed for any sample aged for 24 days. A moderate increment in droplet sizes is observed during this period. The droplet size increases significantly when more than 15 vol % biodiesel is used in the fuel blend. Those samples show stratification after 65 storage days. An increment in the zero-shear viscosity of the samples over aging helps hinder the rapid coalescence of the droplets, thus preventing phase separation. Furthermore, the thermal stability of the samples is also investigated at elevated temperatures up to 50 °C. The nEs are found to be highly stable within this temperature range and showed a moderate change in mean droplets size, especially when the concentration of biodiesel in the emulsified fuel blend is less than 15 vol %.

Design of Water in Diesel Emulsion Fuel using Computer-Aided Approach

Design of Water in Diesel Emulsion Fuel using Computer-Aided Approach

수분을 함유한 바이오디젤 에멀젼 연료 액적의 연소 특성 연구

This study conducted droplet combustion experiments on diesel, palm oil, and canola oil containing water to compare and analyze droplet combustion characteristics. This experiment was performed depending on the changes in various droplet diameters of 1.387 ~ 1.731 mm of diesel(D100), biodiesel(BDC100 and BDP100), and water emulsion diesel and biodiesel(D-W, BDC-W, and BDP-W) to compare combustion behaviors such as ignition delay, micro-explosion, flame extinction and lifetime. As a result of the experiments, viscosity makes micro-explosions strong, and strong micro-explosions have the effect of reducing flame extinction time and lifetime. The difference between a micro-explosion and ignition delay with diesel emulsion fuel and biodiesel emulsion fuel is considered to be the difference in properties between the two fuels. The emulsion fuels had a great influence on micro-explosion, flame extinction, and lifetime depending on the viscosity of the fuel. However, diesel emulsion fuels with weak micro-explosion showed increasing ignition delay due to the high latent heat of the water. Based on this, it plans to conduct experiments on the effect of the difference in fuel viscosity on combustion behavior.

Performance and Emission Analysis of Watermelon Seed Oil Methyl Ester and n-Butanol Blends Fueled Diesel Engine

The impact of n-butanol, a next-generation biofuel, with watermelon methyl ester in a constant-speed diesel engine was analyzed. Methyl ester from watermelon seed oil is considered to be a promising alternative source to the standard diesel due to similar characterization. The n-butanol additive was added in small proportions as an oxygenated fuel for reducing emissions, improving thermal efficiency, and accelerating the combustion process. N-Butanol is blended with watermelon methyl ester in the form of emulsions in two different proportions (5% and 10% volume basis). Experiments were conducted with three different emulsions fuels, WME20, W20Bu5D75, and W20Bu10D70, and compared vis-à-vis standard diesel. Investigations revealed that the addition of n-butanol as an enhancer with WME20 improved characteristics owing to its inherent nature of oxygen content. The blending of WME with n-butanol improves brake thermal efficiency when compared to WME20 and slightly matches with standard diesel. The max BTE was recorded 32.79% for WME20Bu10D70 at the crest load. The peak BSFC was 0.26 kg/kWh for W20Bu10D70 at the crest load. The emissions such as CO, smoke opacity, and HC were significantly reduced, vis-à-vis diesel, and the oxides of nitrogen (NOX) and carbon dioxide (CO2) were decreased, relative to WME20. The maximum EGT was 354.98°C for W20Bu10D70 at the crest load. The peak CO emissions were 0.078% for W20Bu5D75 at the crest load. The blending of n-butanol with WME20 reduces the ignition delay while the combustion duration increases with an increase at full load conditions. The emulsion fuels tested in an unmodified engine did no negative impact on the engine stability.

Assessment of CI Engine Performance and Exhaust Air Quality Outfitted with Real-Time Emulsion Fuel Injection System

The main target of the current research work is effectively eliminating fossil fuel dependency and improving the exhaust air quality of conventional Compression Ignition (CI) engines. This research paper demonstrates for the first time that a nanofluid (water without surfactant) stored in separate tanks can be quantified, collected, and immediately emulsified by a high shear mixer before transfer into the combustion chamber of a diesel engine. The experiment was carried out under different load states (25%, 50%, 75% and 100%) with a constant speed of 1500 rpm. Biofuel was extracted from citronella leaves using an energy-intensive process. The 5% water share was used for preparing the biofuel emulsion and nano-biofuel emulsion. A cobalt chromate nanoadditive was used to make the nanofluid. An experimental investigation was performed with prepared test fuels, namely, ultra-low sulphur diesel (ULSD), 100% Citronella (B100), surfactant-free Diesel emulsion (SDE), surfactant-free bioemulsion (SBE), and Surfactant free nano-bioemulsion (SNBE), in a test engine. The properties of the sample test fuels was ensured according to EN and ASTM standards. The observation performance results show that the SNBE blend exhibited lower BTE (by 0.5%) and higher SFC (by 3.4%) than ULSD at peak load. The emission results show that the SNBE blend exhibited lower HC, CO, NOx, and smoke emissions by 23.86%, 31.81%, 2.94%, and 24.63%, respectively, compared to USD at peak load. The CP and HRR results for SNBE were closer to ULSD fuel. Overall, the novel concept of an RTEFI (Real-time emulsion fuel injection) system was proved to be workable and to maintain its benefits of better fuel economy and greener emissions.

Comparison of Diesel Engine Performance between a Mechanical Pump and a Common Rail Fuel Injection System Equipped with Real-Time Non-Surfactant Emulsion Fuel Supply System

The global focus in emulsion fuels is due to the advantages over conventional diesel fuels. It has the capabilities to simultaneously reduce the emissions of NOx and smoke. It also said to reduce the fuel consumption of diesel engine by significant percentages. However, due to the interdependency on surfactant, emulsion fuel does not seem to be possible as alternative fuel in an economic perspective. This is because of the high market price of the commercial surfactant. Therefore, this research focused on non-surfactant W/D that produced by a system known as Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES). RTES has been applied with the goal of investigating the impact on exhaust emissions and fuel consumption of a mechanical pump fuel injection system diesel vehicle (MP) and a common rail fuel injection system diesel vehicle (CR). A one-ton truck represents as MP (Mechanical Pump) and an SUV represent as CR (Common rail) are the test vehicles for the said research. The non-surfactant W/D with 6.5 wt.% of water produced by the RTES used as the test fuel and named as E6.5. It has been emulsified in the RTES right before being injected into the diesel vehicles. The testing was performed on a chassis dynamometer following the West Virginia University 5-peak cycles. The findings show that the utilization of non-surfactant W/D has increased the fuel consumption by 7.39% for MP and 3.2% for CR respectively as compared with base diesel fuel. NOx, smoke emissions and exhaust temperature have significantly reduced by the MP relative to CR vehicles. Overall, the concept of non-surfactant W/D seems to have implementation potential for reducing harmful emissions from both diesel-powered vehicles.