Combustion Characteristics Of Droplets Research Articles

Combustion characteristics of water-oil emulsion droplets with special additives

Relevance. Fuel oil application in power plants is characterized by increased values of underburning and anthropogenic emissions. One way to reduce anthropogenic emissions is the use of oil-water emulsions. Also, additional specialized additives are used to reduce anthropogenic emissions and improve fuel combustion characteristics. Aim. To determine the optimal fuel oil additive to reduce anthropogenic emissions and ignition delay times. Methods. The following additives: ION-M, Rosneft R503V3, Rosneft R502V1 (relative mass concentration 0.5%) were added to the water-oil fuel. The physicochemical properties of fuel oil M-100, as well as the elemental composition of CHNSO, were determined. The rheological characteristics of water-oil fuel compositions were established. Using high-speed photography, the droplet ignition delay times were determined. Using the gas analyzer, it was possible to prevent anthropogenic emissions. Results and conclusions. The results of the study showed that the additive based on a special combination of positively and negatively charged ions (ION M) reduces ignition delay times by 20–60%, when the gas temperature varies in the range from 700 to 900 °C. The addition of the additive based on fatty vegetable acids (P502B3) reduced the ignition delay times by 7–10%, when the temperature changed in the range from 700 to 900 °C relative to water-oil fuel. It was found that when using the P502B1 additive in water-oil fuel, it was possible to reduce the ignition delay times by 15–50%. It was determined that in the presence of combustion catalysts, water binds with heavy hydrocarbons and thus the release of volatile substances occurs faster, i. e. the supplied heat is not wasted on heating water into droplets, but evenly affects the entire volume of fuel. The results of the study of anthropogenic emissions showed that the use of additives when burning water-oil fuel reduces the concentrations of CO, CO2, NO, SO2 by 8, 6, 10 and 13%, respectively, compared to fuel oil.

Assessing the ignition and combustion of a kerosene droplet containing boron nanoparticles coated with polydopamine and polyvinylidene fluoride

In this study, how the coating of polydopamine (PDA) and polyvinylidene fluoride (PVDF) on boron particles affects the ignition and combustion characteristics of kerosene droplets was investigated. In this work, PVDF was first coated onto boron nanoparticles using PDA as a binder to form double-coated composite particles (denoted as B@PF), and then the B@PF particles were blended into kerosene to produce nanofluidic fuels. Various characterization techniques were used to evaluate the ignition and combustion performance of the B@PF composites and the nanofuel droplets, including scanning electron microscopy (SEM), thermogravimetric-differential scanning calorimetry (TG-DSC), laser ignition testing, and single droplet combustion experiments. The results showed that the PDA coating could effectively prevent the moisture absorption of the particles in ambient air and increase the heat release by 42.97 %, while the PVDF coating would have a negative impact on the energy properties of the particles. Pure B particles have the lowest spectral intensity under laser light, which is consistent with the DSC results. The addition of pure B particles to kerosene reduced the ignition delay time by nearly 86 %, while the PVDF coating could enhance the droplet heat transfer to further reduce the ignition delay time. However, the increase in PVDF content negatively affects the combustion rate of the droplets by decreasing the energy properties of the particles. In the final residue combustion stage, the reaction between PVDF and B2O3 increases the burning intensity of the B particles and reduces the size of the combustion residue. Based on the experimental results, a comprehensive model for the ignition, combustion and residue burning of droplets coated with both PDA and PVDF is proposed.

Ignition and combustion characteristics of ultrasonically levitated single droplets of nano‑boron/oxygenated fuel slurries

Addition of boron nanoparticles to liquid oxygenated fuel lead to the formation of nano‑boron slurries with high energy density. This study focuses on ignition and combustion characteristics of single droplets of nano‑boron slurries during ultrasonic levitation and effects of different oxygenated fuels on ignition and combustion characteristics of single droplets. In this study, nano‑boron slurries of boron/ethanol, boron/1-hexanol, boron/dimethyl carbonate, boron/triacetate, boron/propylene glycol monomethyl ether and boron/tripropylene glycol monomethyl ether with 10 wt% solid loading were prepared. Moreover, an ultrasonic levitation system was designed and established, which was used for igniting single droplets in ultrasonic levitation state. The results indicate that ignition and combustion process of levitated single droplets of nano‑boron slurries can be divided into three stages: a stable endothermic stage, an oscillation and micro-explosion stage and an aerosol combustion stage. Smoke was observed before aerosol combustion stage of boron/triacetate and boron/tripropylene glycol monomethyl ether, whereas flame jets were observed during combustion of other fuels. Furthermore, emission spectra of BO2 with high intensity could be observed during aerosol combustion stage. A shorter main chain length of oxygenated fuel facilitates ignition of nano-B slurries. Boron/propylene glycol monomethyl ether exhibited shortest ignition delay, which was approximately 13.8% shorter than that of boron/tripropylene glycol monomethyl ether with the longest ignition delay. Furthermore, a longer main chain length of oxygenated fuel facilitates combustion of nano-B slurries. Nano‑boron slurries with longer main chains (boron/1-hexanol, boron/triacetate and boron/tripropylene glycol monomethyl ether) exhibited brighter and larger flames, regardless of whether they were alcohols, esters or ethers, and quenched zones with bright and clearly delineated edges were observed. Intensity integral and maximum intensity of emission of these three fuels were also higher than those of other fuels. Boron/triacetate demonstrated the best combustion performance, with maximum intensity and intensity integral at 547.8 nm being 3.88 times and 1.9 times those of boron/ethanol, respectively, which has the worst combustion performance. This study provides a theoretical basis and experimental reference for the application of oxygenated-fuel-based nano‑boron slurries and their base liquid fuel selection.

Experimental study on microwave-induced puffing, micro-explosion, and combustion characteristics of ammonium dinitramide-based liquid propellant droplets

Microwave ignition technology has the advantages of high ignition energy, stable ignition, and spatial multi-point ignition. These advantages make this technology promising for future application in green single-component propellants. In this paper, the ignition characteristics of ammonium dinitramide (ADN)-based liquid propellant droplets under the influence of microwaves at room temperature are investigated using experimental methods. The effects of microwave power on puffing, micro-explosion, and combustion behavior of ADN-based liquid propellant droplets were studied. The droplet and flame diameters were statistically related to time, and the microwave-assisted droplet ignition mechanism was analyzed. A new rectangular waveguide resonant cavity was designed in which the droplet is placed at the maximum electric field strength of the device. The droplet morphology and flame profile inside the resonant cavity were photographed with a high-speed camera. The experimental results showed that the microwave positively influenced the puffing, micro-explosion, and combustion behavior of droplets. When the microwave power was increased from 200 to 280 W, the total droplet evaporation time and ignition delay time were reduced by 56.5% and 35.2%, respectively. The positive effects of microwaves on combustion have been summarized as the thermal effect of microwaves on polar molecules and the promotion of fuel oxidation reactions by microwave-induced plasma. The plasma was found to control the development of the initial flame propagation front and to influence the temperature during the combustion reaction process. In this paper, we propose the mode of droplet combustion under microwave induction as a plasma discharge and several stages of the droplet combustion process. This research provides novel insight into the study of the microwave ignition mechanism of liquid fuels.

Disruption and microexplosion mechanisms of burning alcohol droplets with the addition of nanoparticles

Microexplosions of burning liquid fuels have been actively investigated and considered due to the advantage for substantially increasing the overall burning rate. This study concerns possible control of microexplosion occurrence by adding nanoparticles in alcohol fuel without effects of surfactant and ignitable particles as usually seen in the literature. In addition, the essential characteristics and differences between various particles on combustion are discussed. Specifically, we have added three types of ceramic nanoparticles into butanol and isopropanol droplets under different convection environments, i.e., forced convection and natural convection in normal gravity, and free convection in microgravity. A suspended droplet method was performed under convection-free and natural convective conditions while a free-falling droplet method provided a forced convection environment. It was observed that the combustion characteristics of droplets changed from extinction to burnout or from burnout to microexplosion by using different base fuels, by increasing the intensity of flow convection, or by using different kinds of nanoparticles. During combustion, droplets would deform due to the presence of gelation in the outer layer when Al2O3 or SiO2 nanoparticles were added, but not for TiO2. This yielded one of the key factors leading to microexplosions, in addition to the amount of heat absorption during the burning. For the latter, specifically, microexplosions happened when butanol/SiO2 droplets were tested, but not for butanol/Al2O3 droplets. By comparing the infrared absorptivity of Al2O3 and SiO2, distinct amount of absorbed infrared radiation was demonstrated. Such a difference in heat absorption was also key to the creation of microexplosion. As a consequence, microexplosions could be generated when nanoparticles were added into the fuel and formed gelation on the droplet surface, which trapped bubbles in the droplet, while sufficient heat was absorbed by the particles during the burning. The resulted consumption rate had increased by 46% compared to that of pure fuel.

Combustion Characteristics of Coal-Water Slurry Droplets in High-Temperature Air with the Addition of Syngas

An experimental study of the ignition and combustion processes of coal-water slurry (CWS) droplets based on coal enrichment waste in a high-temperature oxidizer at 650–850 °C with a syngas addition was carried out. The fuel slurry was a mixture of finely dispersed solid combustible particles (coal sludge, 10–100 µm in size) and water. The syngas was a product of biomass pyrolysis and two waste-derived fuels in a laboratory gasifier. Composition of the syngas was controlled by a precision analytical gas analyzer. The feasibility of co-firing CWS with syngas was experimentally established. Under such conditions, the CWS droplets ignition process was intensified by 15–40%, compared to fuel combustion without the addition of syngas to the combustion chamber. The greatest positive effect was achieved by adding the gas obtained during the biomass pyrolysis. The ignition delay times of CWS droplets are 5.2–12.5 s versus 6.1–20.4 s (lower by 15–39%) when ignited in a high-temperature medium without adding syngas to the combustion chamber. Based on the results obtained, a concept for the practical implementation of the CWS combustion technology in a syngas-modified oxidizer medium is proposed.

Experimental studies on combustion and atomization characteristics of aliphatic and aromatic hydrocarbons droplets

This study focused on how the properties of alcohols (ethanol, methanol, n-butanol), ketones (acetone), alkanes (hexane), esters (ethyl acetate), methyl benzenes (toluene), and ethers (diethyl ether) shape individual combustion and atomization behaviors. The experimentation conducted at the droplet scale involved suspending fuel droplets on a ceramic wire and subsequently igniting them for analysis. Experiments were recorded with a high-speed camera and a thermal camera with a spectral range of 7.5–14 μm. The results showed that the flame of the oxygenated fuel droplets, unlike non-oxygenated fuels, has a high non-luminous region seen throughout the combustion process. The diameter reduction of the fuel droplets during combustion tended to obey the D2-law. Single and multicomponent fuel droplets are hemispherical for preheating (Stage I) and hemispherical in droplet disruption mode for combustion and droplet diameter decrease (Stage II). Hexane, diethyl ether, and ethyl acetate were the fuels that were extinguished in the shortest time among the fuels studied here with extinction times of 1.021 s, 0.925 s, and 0.885 s, respectively. Hexane, diethyl ether, acetone, and diesel droplets had the minimum ignition delay times according to the experimental conditions in this study. In terms of maximum flame temperature, ethyl acetate exhibited the highest value among oxygenated fuel droplets, reaching 155 °C, while toluene demonstrated the highest maximum flame temperature of 244 °C among all fuel types, including non-oxygenated fuels.

The Effect of Alcohol Compounds on Droplet Combustion Characteristics of Unsaturated Fatty Acid of Linoleic Acid

Alcohol compounds have become a popular choice as additives for improving the performance of biodiesel. However, given the complexity of biodiesel, which is composed of various components of vegetable oil, it requires intensive research to fully understand its behavior. This study aims to investigate the impact of alcohol compounds on the droplet combustion characteristics of linoleic acid, an unsaturated fatty acid. Four alcohol compounds, namely methanol, ethanol, propanol, and butanol, were utilized to evaluate their effects on the combustion properties of the fuel mixtures. The droplet combustion characteristics were observed under normal atmospheric pressure and temperature conditions, with the fuel mixture consisting of 80 % linoleic acid and 20 % alcohol compounds. Our findings indicate that the addition of alcohol compounds to linoleic acid significantly reduced the ignition delay time, although the droplet lifetime was slightly increased. Moreover, it was observed that alcohols with shorter carbon chains had a greater impact on reducing the ignition delay time. Additionally, the results demonstrated that the alcohol compounds could accelerate the rate of increasing combustion temperature, reduce soot formation, and shorten the duration of soot formation. Furthermore, it was found that alcohol with a short carbon chain had a more pronounced effect on the overall combustion characteristics of linoleic acid. Overall, our study sheds light on the effects of alcohol compounds on the droplet combustion characteristics of linoleic acid, providing valuable insights for the optimization of biodiesel performance. HIGHLIGHTS Alcohol has a significant impact on the properties of unsaturated fatty acids, specifically on factors such as ignition delay time, droplet lifetime, temperature, flame dimension, and soot production The addition of alcohol as an additive, results in a reduction in soot generation and a shorter duration of soot formation The length of the carbon chain in the alcohol additive plays a crucial role in the combustion properties of linoleic acid. Alcohols with shorter carbon chains have a greater impact on the overall combustion properties GRAPHICAL ABSTRACT

Characterizing combustion and atomization of PODEn and ethanol/PODEn binary droplets

Polyoxymethylene dimethyl ethers (PODEn) constitute a promising e-fuel family from CO2 feedstock, while their droplet combustion characteristics are still insufficiently understood. This work reports an experimental investigation on the combustion and atomization characteristics of PODEn (n = 1–4) and ethanol/PODEn binary droplets, with special attentions on the influence of content ratio, highly volatile component, and boiling point difference between components (ΔTbp). History of square of normalized droplet diameter was recorded during the combustion process, from which two stages including stable combustion and atomization can be derived. Three different behaviors, i.e., puffing, ejection, and micro-explosion, were observed in the atomization stage of the investigated binary droplets with ΔTbp generally greater than 50 K, while only puffing and ejection were observed as ΔTbp becomes lower. For PODE1/PODE4 binary droplets, the atomization index which defines the relative reduction of droplet lifetime caused by atomization is found to peak at 70 % PODE1, while for ethanol/PODE4 binary droplets, the atomization index rises quickly at small ethanol content and thus peaks early at 50 % ethanol. This is mainly because that the evaporation propensities of ethanol and PODE4 are both promoted in the ethanol/PODE4 binary droplets as their activity coefficients become greater than one, while those of PODE1 and PODE3 are both suppressed in the PODE1/PODE4 binary droplets. For both PODEn and ethanol/PODEn binary droplets at the fixed content ratio of 50 %/50 %, the atomization delay time and micro-explosion intensity both increase with ΔTbp first and keep almost invariable as the weakly volatile component varies from PODE3 to PODE4, while the atomization index becomes proportional to ΔTbp. On the other hand, the ethanol/PODEn binary droplets generally have higher micro-explosion intensities and consequently higher atomization indices, indicating their stronger atomization propensities than the PODEn binary droplets.

Cenosphere Formation and Combustion Characteristics of Single Droplets of Vacuum Residual Oils

ABSTRACT The ignition, combustion characteristics, and cenosphere formation of single droplets combustion of four vacuum residues (VRs) from different refineries with various asphaltene contents were studied experimentally. The single droplets of VRs were suspended at the tip of a silicon carbide fiber and heated in air at temperatures of 973 and 1023 K, respectively, in an electrically heated tube furnace. The ignition and combustion behavior of the VRs were recorded using a CCD camera, which enabled the determination of droplet size, ignition delay time, flame duration, and cenosphere size. The effect of initial droplet size, gas temperature, and asphaltene content on the ignition delay time, flame duration, cenosphere morphology, and particle size were investigated. The whole ignition and combustion process of single droplets of the VRs consisted of five stages in succession: (1) pre-ignition, mainly involving the evaporation of highly volatile components from the droplet surface; (2) steady combustion of fuel vapors evaporated from the droplet surface; (3) splashing combustion of fuel vapors evaporated from droplet interior; (4) disruptive combustion due to thermal decomposition of asphaltene; and (5) solid residue ignition and combustion. A visible and sooty flame was formed upon ignition and lasted during stages 2–4. The droplet size increased sharply in the stage 4 due to the thermal decomposition of asphaltene, which was more profound for VRs with higher asphaltene content and at higher gas temperatures. The ignition delay time increased with increasing initial droplet size and gas temperature but varied little as the asphaltene content in the VRs increased, suggesting that the ignition process of VRs was controlled by the vaporization of high volatile components on the droplet surface. The thermal decomposition of asphaltene produced solid residue, which was in the form of a cenosphere with the shell thickness being ca. 20 μm and a number of blowholes presented in the shell. The VRs with higher asphaltene content had more and bigger blowholes. The ratio of cenosphere particle size to initial droplet size is independent of the initial droplet size but almost increased linearly with the asphaltene content in the VRs.

The influence of various preheating and direction of magnetic field on combustion characteristics of palm oil droplets for boiler combustion in power generation system

Research has been carried out on the effect of various preheating and the direction of the magnetic field on the flame characteristics of droplet combustion. This study is important to substitute fuel from fossils with vegetable oil that is environment friendly. The variations of the magnetic field are south-south pole, north-north pole, south-north pole, north-south pole, and without. A drop of palm oil is placed on a type K thermocouple between two magnetic rods. The high-speed camera of 120 fps from the front recorded the flame from the start until it went out. The researcher found out the influence of various preheating in palm oil and the magnetic characteristics and behavior of the flame. The direction of the north-south magnetic field had a higher magnetic field strength, caused the droplet combustion to increases resulting in a wider flame but a lower and more stable height compared to other magnetic field directions. The speed of combustion affected by the magnetic field intensity which resulted the flow rate of O2, therefore the combustion speed happened quickly because between O2 and the fuel molecules easily react and were more flammable. The strength of the magnetic field increased oxygen concentration and fuel molecule around the reaction zone causing a short burning, resulting in a change delay time the shorter but the flame temperature increased. Stability, shape, temperature, height, delay time and combustion duration were highly valuable to design an efficient heat generator industry with the addition of magnet field. This study provides insight into the influence of magnetic field direction in magnetic field intensity on droplet combustion characteristics for boiler combustion in the power generation system

Experimental study of droplet combustion and diesel engine characteristics for Azolla biodiesel

ABSTRACT This study pertains to studying the feasibility of the third-generation biodiesel obtained from one of the algae species known as Azolla microphylla by exploring their fundamental droplet combustion behavior and diesel engine characteristics. Firstly, the droplet evolution and burn rate are investigated for diesel, Azolla100, and Azolla50 (50% biodiesel +50% diesel) based on the experimental study of suspended droplet combustion. The diesel droplet showed steady combustion with linear regression for the decrease in droplet surface with time throughout its lifetime, while the Azolla100 and Azolla50 droplets showed a linear trend initially, and after a certain point, they resulted in a non-linear trend as a result of disruptive burning. The evaporation and burn rate was found to be higher for Azolla100 and Azolla50 than diesel during the steady burning period and thereafter it decreased with increasing Azolla concentration. The time evolution of droplet combustion images indicated that with increasing biodiesel concentration, the combustion duration was decreased due to secondary droplet ejections and microexplosion, and the residue burning duration was increased. The microexplosion increased the rate of combustion, however, droplet ejection resulted in incomplete combustion. Secondly, the engine experiments were performed for Azolla50 at different fuel injection pressures. The results showed that in-cylinder pressure and Brake thermal efficiency (BTE) for Azolla50 at 300 bar injection pressure were lower than diesel due to limitations with the physical properties of biodiesel. In order to improve the engine characteristics of Azolla50, this study increased the fuel injection pressure to 900 bar. As a result, the BTE for Azolla50 at 900 bar injection pressure is improved by 9.2% and 10.2% at low and full load conditions, respectively, compared to Azolla50 at 300 bar injection pressure. Overall, the spray-driven combustion for Azolla50 is limited by the physical properties of the biodiesel, which affects the mixture formation. On the other hand, the microexplosion and droplet ejection observed with the biodiesel during the combustion study would favor the combustion by improving the atomization and mixing process.

The impact of ethanol addition on the droplet combustion mechanism of saturated and unsaturated fatty acid/fatty acid methyl ester molecules

The combustion of biodiesel requires complex analysis because it is composed of multicomponent constituents. The use of additives in biodiesel is an option widely used to improve the combustion performance of the fuel blend. The droplet combustion characteristics of single compounds of biodiesel and vegetable oil constituents with ethanol additives were investigated under normal gravity at room temperature and atmospheric pressure. This study reveals the different combustion mechanisms and their interactions with ethanol between laurate and oleate as the base fuel. Ethanol breaks the base fuel into smaller molecular aggregates, reducing the fuel blend density with many larger gaps between the clusters. Thermal expansion and child droplet ejection are key mechanisms that effectively increase the total droplet surface area, causing an increase in the diffusion contact between the fuel vapor and the air. Three mechanisms of child droplet ejection occur during the heating phase until the microexplosive combustion phase. The period of child droplet ejection during the microexplosive combustion phase is determined by the boiling point difference and the solubility level between the base fuel and ethanol. The addition of ethanol increases the burning rate of the fuel mixture with a higher peak temperature in the laurate-ethanol blend compared to the base fuel. Ethanol plays an important role in delaying the start of evaporative cooling with a significant temperature increase rate. This behavior is an effective mechanism to initiate droplet combustion with a short ignition delay time.

Investigation of the Physical Properties and Droplet Combustion Analysis of Biofuel from Mixed Vegetable Oil and Clove Oil

The study of vegetable oil used as fuel in conventional engines leads to problems like the low volatility and high viscosity. This research aims to evaluate the droplet combustion characteristics that correlated with the density, viscosity, and the flash point of the biofuel from mixed vegetable oil with clove oil. Biofuels used in research are Jatropha Oil (CJO), Kapok Oil (KSO), Coconut oil (CCO), and all biofuel mixed with clove oil in 5% basis volume. Fuel properties that tested both biofuel and fuel mixture using the ASTM method are density (ASTM D1298), viscosity (ASTM D445), The flash point (ASTM D93). The droplet combustion experiment used suspended droplets placed in the junction of the K-type thermocouple and the Ni-Cr wire (as the coil heater) to heat the droplet until the combustion occurred. The result indicates that adding 5% clove oil in biofuel creates higher density, the viscosity decreases until 10%, and the flash point decrease to 30%. Droplet combustion results that adding 5% clove oil creating a more complete combustion process in CCO than KSO and CJO. Higher viscosity in KSO and CJO leads to eugenol and terpene (clove oil compound) trapping in the fuel droplet. Due to eugenol and terpene having great volatility, they are evaporating rapidly leading to secondary atomization and micro-explosion phenomena.

Influence of micron-sized aluminum particles on micro-explosion and combustion characteristics of ethanol-biodiesel droplets under co-heat flow

• The characteristics of droplets doped with micron-sized particles were studied. • Increasing the particle size will promote the micro-explosion phenomenon. • The droplet heating time will vary due to changes in particle content. • The particle content of the optimal micro-explosion intensity is about 20%. As a high-energy metal fuel, aluminum powder particles (AP) have long been used as fuel propellants and combustion-supporting additives in explosives to meet the design requirements of a new generation of high-energy–density fuels. In this experiment, the micro-explosion and combustion characteristics of ethanol-biodiesel mixed droplets with different aluminum powder particle contents and particle sizes were studied under high temperature and pure oxygen environment. In order to better control the experimental variables, a more accurate single-droplet suspension method was adopted in this experiment. The entire evaporation and combustion process of the mixed fuel was completely recorded and analyzed by using high-speed photography technology, binarization imaging technology and droplet optimization algorithms. The experimental results show that when the content of aluminum powder particles remains unchanged, increasing the particle size of aluminum powder in the mixed droplets will promote the micro-explosion phenomenon. When the particle size of the aluminum powder contained in the mixed fuel is different, the increase of the particle content will have a completely different effect on the heating time of the droplet. When the particle size of aluminum powder particles is small, the combustion duration of the mixed droplets increases with the increase of aluminum powder content, while the opposite results are shown when the aluminum powder particles are larger. Increasing the amount of aluminum powder also extends the full life of the droplets. In addition, this study introduces the microburst intensity (MI), which provides a new idea and method for laterally comparing the microburst phenomena of fuel droplets with different initial diameters. For mixed fuel containing micron-sized aluminum particles, the particle content that produces the best micro-explosion intensity is about 20%.

Karaktersitik pembakaran droplet minyak nabati Indonesia

Research has been carried out on the combustion characteristics of Indonesian vegetable oil droplets. Currently, Indonesia is still developing CPO as a source of renewable fuel to replace diesel. The problem is, CPO is used as a food source so that it will affect food scarcity. Vegetable oils used in this study include CCPO, CJO, CCO and CCIO. The volume of the droplets tested was 1.25-1.31 ml and the drops were placed on a 0.1 mm type K thermocouple. The flame characteristics of the droplets tested included flame stability, ignition delay time, and temperature and flame height. The results showed that vegetable oils with higher viscosity produced more stable flames, but had low temperatures and short flames. This is because high viscosity vegetable oils produce less intense microbursts. While the ignition delays time of CCO is faster than CCPO even though it has the highest flash point. This happens because the polar nature of CCO can attract oxygen more strongly. In addition, the fatty acid content of vegetable oils also has a significant impact on fire characteristics. This is indicated by CCO which has a high content of saturated fatty acids and tends to produce a short flame.

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.

Influence of Mixture Composition Between Soybean Oil and Diesel Fuel on Characteristic of Droplets Combustion

<p class="02abstracttext">Depleting oil reserves has encouraged many researchers to search for new energy resources. Of many alternatives, soybean oil has been proposed as biodiesel. In this study, influence of mixture composition of soybean oil and diesel fuel on the droplet combustion characteristics was investigated. These characteristics included Ignition delay time, fire visualization, flame temperature and burning rate. The mixture comprises 10 to 50% soybean oil while the rest are Pertamina Dex diesel fuel. The study shows that flash point temperature, ignition delay time and burning rate increase as soybean oil content increases. In contrary, the flame height decreases with increasing soybean oil content.</p>

The Response of Adding Nanocarbon to the Combustion Characteristic of Crude Coconut Oil (CCO) Droplets

One of the strong candidates for biodiesel is Crude Coconut Oil (CCO) but its high viscosity cannot be applied directly without treatment. Therefore, nanocarbon is added to reduce the viscosity of CCO. Nanocarbon is a natural material with semiconductor properties, a good heat conductor, and can attract other molecules. By adding nanocarbon, it is expected to reduce the viscosity of CCO. This study aimed to determine the combustion characteristics of droplets on CCO by adding nanocarbon by 1% and 5%. The method used was a true experiment with droplets, which dripped on the thermocouple with activation energy from the heater. The results showed that CCO burned 0.933s with a droplet diameter of 4.307mm, droplet diameter of 5.472 mm. By adding 5% nanocarbon to CCO, the CCO burned faster, more reactive, and the ignition was shorter than the pure CCO and 1% CCO.

In-flame soot quantification of N-Hexadecane droplets using diffused back-illumination extinction imaging

To gain insights into spray combustion, the combustion characteristics of single droplets need be investigate. In this study, soot production measurements were performed on single droplet of N-Hexadecane using the two optical techniques of natural flame luminosity imaging and diffused back-illumination extinction imaging (DBIEI). These measurements were performed in a suspended single-droplet combustion setup under ambient temperature and atmosphere. The experimental results from both methods are positively correlated with the combustion process. The images captured using the two methods clearly show the premixed and non-premixed combustion periods. The ratio of soot radiation to flame radiation is nearly constant in non-premixed combustion. The DBIEI results for the natural soot luminosity indicate a shorter distance than the attenuated soot intensity along the vertical direction. The results demonstrate that DBIEI technique is capable of quantitatively measuring the instantaneous soot formation during single droplet combustion.