Droplet Combustion Behavior of Vegetable Oil Surrogate Fuel Enhanced with Alcohols
DOI:
https://doi.org/10.48048/tis.2025.9769Keywords:
Renewable energy, Droplet combustion, Oleic acid, Alcohol, Microexplosive behavior, Volumetric expansion, Nucleation modes, Soot formation, Flame standoff ratio, Flame luminosityAbstract
Internal combustion engines play an essential role in industry and transportation due to their reliability, efficiency, and cost-effectiveness. However, emissions produced from fossil fuels impact environmental degradation, so alternative fuels are needed to increase combustion efficiency and reduce emissions. Vegetable oil is introduced as a renewable energy source, which is potentially used as a substitute for diesel fuel. However, vegetable oils are not fully compatible with diesel fuels, although they have some advantages regarding their properties. Therefore, this work aims to study the mechanism and enhancement of the single isolated droplet combustion behavior of oleic acid as the vegetable oil surrogate compound by adding 20 vol% of alcohol with different molecular structures. The droplet was suspended on the fiber to observe the combustion behavior under static conditions. The droplet dynamics and microexplosive behavior are investigated using spatial and temporal tracking under atmospheric pressure and normal gravity conditions. The post-processing procedure was used to observe the evolution of flame and droplet diameter. The fuel blends exhibit severe volumetric expansion followed by child droplet ejection with various droplet breakup structures due to different nucleation modes. This mechanism is essential to enlarge the fuel reaction zone with ambient air, which shortens the droplet lifetime with a lower ignition point. Methanol significantly reduces the droplet lifetime, while only 2-propanol reduces the ignition delay and burning lifetime among alcohol additives. Methanol addition generates the highest droplet peak temperature due to the faster burning rate, even though it has a lower energy density. Alcohol increases the flame standoff ratio due to the microexplosive behavior. During the unsteady and quasi-steady combustion phases, an elongated flame structure is formed due to natural convection, which is also related to soot formation. Alcohol diminishes the sooting propensity of oleic acid combustion with lower flame luminosity.
HIGHLIGHTS
- Triggering microexplosive behavior enhances droplet combustion of oleic acid.
- High-volatility alcohol greatly shortens the droplet lifetime of the fuel blends.
- Droplet breakup structures depend on bubble formations and nucleation modes.
- Alcohol additives increase ignition probability with a lower ignition point.
- Alcohols reduce soot formation with a lower flame luminosity profile.
GRAPHICAL ABSTRACT
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J Han, LMT Somers, R Cracknell, A Joedicke, R Wardle and VRR Mohan. Experimental investigation of ethanol/diesel dual-fuel combustion in a heavy-duty diesel engine. Fuel 2020; 275, 117867.
W Shang, J Cao, S Yang and Z He. In-flame soot quantification of N-Hexadecane droplets using diffused back-illumination extinction imaging. Case Studies in Thermal Engineering 2022; 30, 101699.
Y Zhang, R Huang, Y Huang, S Huang, Y Ma, S Xu and P Zhou. Effect of ambient temperature on the puffing characteristics of single butanol-hexadecane droplet. Energy 2018; 145, 430-441.
D Nurmukan, MV Tran, YM Hung, G Scribano and CT Chong. Effect of multi-walled carbon nanotubes on pre-vaporized palm oil biodiesel/air premixed flames. Fuel Communications 2021; 8, 100020.
N Jeyakumar, B Narayanasamy, D Balasubramanian and K Viswanathan. Characterization and effect of Moringa Oleifera Lam. antioxidant additive on the storage stability of Jatropha biodiesel. Fuel 2020; 281, 118614.
M Lapuerta, JJ Hernandez, D Fernandez-Rodriguez and A Cova-Bonillo. Autoignition of blends of n-butanol and ethanol with diesel or biodiesel fuels in a constant-volume combustion chamber. Energy 2016; 118, 613-621.
M Plank, G Wachtmeister, E Remmele, K Thuneke and P Emberger. Ignition characteristics of straight vegetable oils in relation to combustion and injection parameters, as well as their fatty acid composition. Fuel Processing Technology 2017; 167, 271-280.
M ElKelawy, HA Bastawissi, EA El-Shenawy, H Panchal, K Sadashivuni, D Ponnamma, M Al-Hofy, N Thakar and R Walvekar. Experimental investigations on spray flames and emissions analysis of diesel and diesel/biodiesel blends for combustion in oxy-fuel burner. Asia-Pacific Journal of Chemical Engineering 2019; 14(6), e2375.
EG Giakoumis. Analysis of 22 vegetable oils’ physico-chemical properties and fatty acid composition on a statistical basis, and correlation with the degree of unsaturation. Renewable Energy 2018; 126, 403-419.
E Marlina, W Wijayanti, L Yuliati and ING Wardana. The role of pole and molecular geometry of fatty acids in vegetable oils droplet on ignition and boiling characteristics. Renewable Energy 2020; 145, 596-603.
D Qi, W Xing, P Luo, J Liu and R Chen. Effect of alcohols on combustion characteristics and particle size distribution of a diesel engine fueled with diesel-castor oil blended fuel. Asia-Pacific Journal of Chemical Engineering 2020; 15(4), e2477.
C Chao, H Tsai, K Pan and C Hsieh. On the microexplosion mechanisms of burning droplets blended with biodiesel and alcohol. Combustion and Flame 2019; 205, 397-406.
H Zhang, Z Wang, Y He, J Huang and K Cen. Interactive effects in 2-droplets combustion of RP-3 kerosene under sub-atmospheric pressure. Processes 2021; 9(7), 1229.
J Wang, X Huang, X Qiao, D Ju and C Sun. Experimental study on evaporation characteristics of single and multiple fuel droplets. Journal of the Energy Institute 2020; 93(4), 1473-1480.
L Wang, J Wang, X Qiao, D Ju and Z Lin. Effect of ambient temperature on the micro-explosion characteristics of soybean oil droplet: The phenomenon of evaporation induced vapor cloud. International Journal of Heat and Mass Transfer 2019; 139, 736-746.
M Mikami, N Motomatsu, K Nagata, Y Yoshida and T Seo. Flame spread between 2 droplets of different diameter in microgravity. Combustion and Flame 2018; 193, 76-82.
M Mikami, K Matsumoto, Y Yoshida, M Kikuchi and DL Dietrich. Space-based microgravity experiments on flame spread over randomly distributed n-decane-droplet clouds: Anomalous behavior in flame spread. Proceedings of the Combustion Institute 2021; 38(2), 3167-3174.
AP Pinheiro, JM Vedovoto, AS Neto and BGM Wachem. Ethanol droplet evaporation: Effects of ambient temperature, pressure and fuel vapor concentration. International Journal of Heat and Mass Transfer 2019; 143, 118472.
K Pandey and S Basu. High vapour pressure nanofuel droplet combustion and heat transfer: Insights into droplet burning time scale, secondary atomisation and coupling of droplet deformations and heat release. Combustion and Flame 2019; 209, 167-179.
EN Rose, V Nayagam, DL Dietrich, MC Hicks, UG Hegde, RE Padilla and FA Williams. Autoignition dynamics of n-dodecane droplets under normal gravity. Combustion Science and Technology 2020; 194(9), 1830-1849.
HY Setyawan and M Zhu. Cenosphere formation and combustion characteristics of single droplets of vacuum residual oils. Combustion Science and Technology 2023; 197(1), 59-76.
Y Zhang, R Huang, Z Wang, S Xu, S Huang and Y Ma. Experimental study on puffing characteristics of biodiesel-butanol droplet. Fuel 2016; 191, 454-462.
K Pan and M Chiu. Droplet combustion of blended fuels with alcohol and biodiesel/diesel in microgravity condition. Fuel 2013; 113, 757-765.
K Meng, Y Wu, Q Lin, F Shan, W Fu and K Zhou. Microexplosion and ignition of biodiesel/ethanol blends droplets in oxygenated hot co-flow. Journal of the Energy Institute 2019; 92, 1527-1536.
J Wang, X Qiao, D Ju, L Wang and C Sun. Experimental study on the evaporation and micro-explosion characteristics of nanofuel droplet at dilute concentrations. Energy 2019; 183(9), 149-159.
MR Chow, JB Ooi, KM Chee, CH Pun, MV Tran, JCK Leong and S Lim. Effects of ethanol on the evaporation and burning characteristics of palm-oil based biodiesel droplet. Journal of the Energy Institute 2021; 98, 35-43.
X Wang, M Dai, J Yan, C Chen, G Jiang and J. Zhang. Experimental investigation on the evaporation and micro-explosion mechanism of jatropha vegetable oil (JVO) droplets. Fuel 2019; 258, 115941.
ING Wardana. Combustion characteristics of jatropha oil droplet at various oil temperatures. Fuel 2010; 89(3), 659-664.
P Muanruksa and P Kaewkannetra. Combination of fatty acids extraction and enzymatic esterification for biodiesel production using sludge palm oil as a low-cost substrate. Renewable Energy 2020; 146, 901-906.
SK Hoekman, A Broch, C Robbins, E Ceniceros and M Natarajan. Review of biodiesel composition, properties, and specifications. Renewable and Sustainable Energy Reviews 2012; 16(1), 143-169.
A Gopinath, K Sairam, R Velraj and G Kumaresan. Effects of the properties and the structural configurations of fatty acid methyl esters on the properties of biodiesel fuel: A review. Journal of Automobile Engineering 2014; 229(3), 357-390.
G Knothe and LF Razon. Biodiesel fuels. Progress in Energy and Combustion Science 2017; 58, 36-59.
N Meiri, P Berman, LA Colnago, TB Moraes, C Linder and Z Wiesman. Liquid-phase characterization of molecular interactions in polyunsaturated and n-fatty acid methyl esters by 1H low-field nuclear magnetic resonance. Biotechnology for Biofuels 2015; 8(1), 96.
RD Misra and MS Murthy. Straight vegetable oils usage in a compression ignition engine - a review. Renewable and Sustainable Energy Reviews 2010; 14(9), 3005-3013.
S Xue, K Hou, Z Zhang, H Liu, C Zhu, X Liu and M He. General models for prediction densities and viscosities of saturated and unsaturated fatty acid esters. Journal of Molecular Liquids 2021; 341, 117374.
LF Ramírez-Verduzco, JE Rodríguez-Rodríguez and ADR Jaramillo-Jacob. Predicting cetane number, kinematic viscosity, density and higher heating value of biodiesel from its fatty acid methyl ester composition. Fuel 2012; 91(1), 102-111.
E Torres-Jimenez, MS Jerman, A Gregorc, I Lisec, MP Dorado and B Kegl. Physical and chemical properties of ethanol-diesel fuel blends. Fuel 2011; 90(2), 795-802.
AI EL-Seesy, Z He and H Kosaka. Combustion and emission characteristics of a common rail diesel engine run with n-heptanol-methyl oleate mixtures. Energy 2021; 214, 118972.
CK Westbrook, CV Naik, O Herbinet, WJ Pitz, M Mehl, SM Sarathy and HJ Curran. Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels. Combustion and Flame 2011; 158(4), 742-755.
CC Lee, MV Tran, BT Tan, G Scribano and CT Chong. A comprehensive review on the effects of additives on fundamental combustion characteristics and pollutant formation of biodiesel and ethanol. Fuel 2021; 288, 119749.
B Waluyo, M Setiyo, S Saifudin and ING Wardana. Fuel performance for stable homogeneous gasoline-methanol-ethanol blends. Fuel 2021; 294, 120565.
E Sukjit, JM Herreros, KD Dearn, R García-contreras and A Tsolakis. The effect of the addition of individual methyl esters on the combustion and emissions of ethanol and butanol-diesel blends. Energy 2012; 42(1), 364-374.
E Marlina, W Wijayanti, L Yuliati and ING Wardana. The role of 1.8-cineole addition on the change in triglyceride geometry and combustion characteristics of vegetable oils droplets. Fuel 2021; 314, 122721.
K Meng, L Bao, Y Shi, K Han, Q Lin and C Wang. Experimental investigation on ignition, combustion and micro-explosion of RP-3, biodiesel and ethanol blended droplets. Applied Thermal Engineering 2020; 178, 115649.
Z Wang, B Yuan, Y Huang, J Cao, Y Wang and X Cheng. Progress in experimental investigations on evaporation characteristics of a fuel droplet. Fuel Processing Technology 2022; 231, 107243.
K Han, Y Liu, C Wang, J Tian, Z Song, Q Lin and K Meng. Experimental study on the evaporation characteristics of biodiesel-ABE blended droplets. Energy 2021; 236, 121453.
X Wang, M Dai, J Wang, Y Xie, G Ren and G Jiang. Effect of ceria concentration on the evaporation characteristics of diesel fuel droplets. Fuel 2019; 236, 1577-1585.
A Kumar, HW Chen and S Yang. Diffusion and its effects on soot production in the combustion of emulsified and nonemulsified fuel droplets. Energy 2023; 267, 126521.
IA Ibadurrohman, N Hamidi, L Yuliati and W Winarto. Droplet combustion behavior of methyl oleate-methyl palmitate fuel blend as the surrogate compounds of palm oil biodiesel. AIP Conference Proceedings 2024; 3090(1), 020002.
DV Antonov, GS Nyashina, RM Fedorenko and AS Filatova. Microexplosive atomization of heterogeneous fuel drops for intensifying their ignition. Chemical and Petroleum Engineering 2019; 55(7-8), 619-626.
HY Nanlohy, ING Wardana, N Hamidi, L Yuliati and T Ueda. The effect of Rh3+ catalyst on the combustion characteristics of crude vegetable oil droplets. Fuel 2018; 220, 220-232.
M Amsal, MV Tran, YM Hung and G Scribano. Experimental study of evaporation of palm biodiesel with multi-walled carbon nanotubes additives at elevated temperatures. International Journal of Environmental Science and Technology 2022; 19(7), 6611-6624.
DCK Rao, S Syam, S Karmakar and R Joarder. Experimental investigations on nucleation, bubble growth, and micro-explosion characteristics during the combustion of ethanol/Jet A-1 fuel droplets. Experimental Thermal and Fluid Science 2016; 89(1), 284-294.
MM Avulapati, LC Ganippa, J Xia and A Megaritis. Puffing and micro-explosion of diesel-biodiesel-ethanol blends. Fuel 2016; 166, 59-66.
X Wang, G Wang, L Wang, J Zhang and J Yan. Ethanol evaporation characteristics of the blends of fatty acid methyl ester and ethanol. Journal of Shanghai Jiaotong University 2021; 26(2), 210-217.
N Hamidi, IA Ibadurrohman, L Yuliati, W Winarto and DB Darmadi. The effect of alcohol compounds on droplet combustion characteristics of unsaturated fatty acid of linoleic acid. Trends in Sciences 2023; 20(7), 6720.
DV Antonov, GV Kuznetsov, PA Strizhak and RM Fedorenko. Micro-explosion of droplets containing liquids with different viscosity, interfacial and surface tension. Chemical Engineering Research and Design 2020; 158, 129-147.
DCK Rao and S Karmakar. Crown formation and atomization in burning multi-component fuel droplets. Experimental Thermal and Fluid Science 2018; 98, 303-308.
N Hamidi and J Nugroho. Single droplet combustion characteristics of petroleum diesel-philippine tung biodiesel blends. Trends in Sciences 2021; 18(24), 1409.
X Huang, J Wang, Y Wang, X Qiao, D Ju, C Sun and Q Zhang. Experimental study on evaporation and micro-explosion characteristics of biodiesel/n-propanol blended droplet. Energy 2020; 205, 118031.
JB Ooi, JH Yap, MV Tran and JCK Leong. Experimental investigation on the droplet burning behavior of diesel-palm biodiesel blends. Energy and Fuels 2019; 33(11), 11804-11811.
IA Ibadurrohman, N Hamidi, L Yuliati, W Winarto and M Mikami. The impact of ethanol addition on the droplet combustion mechanism of saturated and unsaturated fatty acid/fatty acid methyl ester molecules. Fuel 2023; 334, 126731.
Y Zhang, R Huang, Y Huang, S Huang, P Zhou, X Chen and T Qin. Experimental study on combustion characteristics of an n-butanol-biodiesel droplet. Energy 2018; 160, 490-499.
S Parag and V Raghavan. Experimental investigation of burning rates of pure ethanol and ethanol blended fuels. Combustion and Flame 2009; 156(5), 997-1005.
IA Ibadurrohman, N Hamidi and L Yuliati. The role of the unsaturation degree on the droplet combustion characteristics of fatty acid methyl ester. Alexandria Engineering Journal 2022; 61(3), 2046-2060.
IA Ibadurrohman, N Hamidi, L Yuliati and BA Valentino. Experimental investigation on the effect of carbon chain length to the droplet combustion characteristic of fatty acid methyl ester. IOP Conference Series: Materials Science and Engineering 2021; 1034, 012060.
H Zhang, Z Wang, Y He, J Xia, J Zhang, H Zhao and K Cen. Ignition, puffing and sooting characteristics of kerosene droplet combustion under sub-atmospheric pressure. Fuel 2021; 285, 119182.
Á Muelas, P Remacha and J Ballester. Droplet combustion and sooting characteristics of UCO biodiesel, heating oil and their mixtures under realistic conditions. Combustion and Flame 2019; 203, 190-203.
Y Zhong, J Xu, Y Pan, Z Yin, X Wang, Y Zhou and Q Huang. Combustion characteristics of aromatic-enriched oil droplets produced by pyrolyzing unrecyclable waste tire rubber. Fuel Processing Technology 2022; 226, 107093.
G Singh, M Esmaeilpour and A Ratner. Effect of carbon-based nanoparticles on the ignition, combustion and flame characteristics of crude oil droplets. Energy 2020; 197, 117227.
J Wang, Q Zhang, K Liang and J Xu. Micro-explosion enhanced combustion of Jatropha oil/2,5-dimethylfuran (DMF) blended fuel droplets. Fuel 2023; 331, 125807.
G Singh, M Esmaeilpour and A Ratner. The effect of acetylene black on droplet combustion and flame regime of petrodiesel and soy biodiesel. Fuel 2019; 246, 108-116.
HY Setyawan, M Zhu, Z Zhang and D Zhang. Ignition and combustion characteristics of single droplets of a crude glycerol in comparison with pure glycerol, petroleum diesel, biodiesel and ethanol. Energy 2016; 113, 153-159.
YC Liu, Y Xu, MC Hicks and CT Avedisian. Comprehensive study of initial diameter effects and other observations on convection-free droplet combustion in the standard atmosphere for n-heptane, n-octane, and n-decane. Combustion and Flame 2016; 171, 27-41.
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