• Energy Research

Biodiesel lubricity is a crucial factor influencing engine performance and longevity, primarily determined by its fatty acid composition. This study evaluates the tribological properties of biodiesel derived from 15 different feedstocks using High-Frequency Reciprocating Rig (HFRR) tests, 3D-laser microscopy, Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS). The results indicate that biodiesel with higher unsaturation levels, particularly those rich in monounsaturated and polyunsaturated fatty acids, exhibits superior lubricity, characterized by reduced wear scar diameters and enhanced film formation. Conversely, biodiesels with high saturated fatty acid content demonstrate larger wear scar diameters and lower film formation efficiency, leading to increased friction and wear. To further analyze the impact of fatty acid composition on lubricity, an artificial intelligence (AI)-based approach using the Adaptive Boosting (AdaBoost) algorithm was implemented. The AI model effectively predicts wear scar diameter, friction coefficient, and film formation, providing insights into the complex interactions between fatty acid profiles and tribological performance. Feature importance analysis and sensitivity evaluation reveal that polyunsaturated fatty acids significantly enhance lubricity, while an optimal balance between saturated and unsaturated fatty acids is necessary to achieve stable frictional behavior. These findings emphasize the potential of AI-driven predictive modeling as a cost-effective tool for optimizing biodiesel lubricity, reducing the need for extensive experimental trials. The integration of advanced tribological testing and AI analysis offers a deeper understanding of biodiesel's lubrication mechanisms, supporting the development of high-performance, sustainable biofuels.

Biodiesel lubricity is a crucial factor influencing engine performance and longevity, primarily determined by its fatty acid composition. This study evaluates the tribological properties of biodiesel derived from 15 different feedstocks using High-Frequency Reciprocating Rig (HFRR) tests, 3D-laser microscopy, Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS). The results indicate that biodiesel with higher unsaturation levels, particularly those rich in monounsaturated and polyunsaturated fatty acids, exhibits superior lubricity, characterized by reduced wear scar diameters and enhanced film formation. Conversely, biodiesels with high saturated fatty acid content demonstrate larger wear scar diameters and lower film formation efficiency, leading to increased friction and wear. To further analyze the impact of fatty acid composition on lubricity, an artificial intelligence (AI)-based approach using the Adaptive Boosting (AdaBoost) algorithm was implemented. The AI model effectively predicts wear scar diameter, friction coefficient, and film formation, providing insights into the complex interactions between fatty acid profiles and tribological performance. Feature importance analysis and sensitivity evaluation reveal that polyunsaturated fatty acids significantly enhance lubricity, while an optimal balance between saturated and unsaturated fatty acids is necessary to achieve stable frictional behavior. These findings emphasize the potential of AI-driven predictive modeling as a cost-effective tool for optimizing biodiesel lubricity, reducing the need for extensive experimental trials. The integration of advanced tribological testing and AI analysis offers a deeper understanding of biodiesel's lubrication mechanisms, supporting the development of high-performance, sustainable biofuels.

This study examined how different feedstocks and alcohol types affect biodiesel properties and lubrication performance. Five feedstocks (palm, sunflower, rice bran, pork lard, and rapeseed) were transesterified using methanol and ethanol, followed by comprehensive analysis of their properties and lubricity characteristics according to ASTM standards and ISO 12156–1. Gas chromatography revealed distinct fatty acid profiles across feedstocks, with unsaturated fatty acids ranging from 53.4 % to 91.1 %. Ethyl esters demonstrated 5.47–16.65 % higher kinematic viscosity but improved lubrication properties compared to methyl esters, showing up to 13.9 % smaller wear scar diameters and 4–25 % shallower wear depths in high-frequency reciprocating rig (HFRR) tests. Notably, biodiesels from feedstocks with higher polyunsaturated fatty acid content, particularly sunflower (58.7 %), exhibited superior lubricity with wear scar diameters of 150–156.5 μm. While ethyl esters showed better lubrication, methyl esters demonstrated 0.42–0.80 % higher density and 1.92–5.88 % higher heating values. Surface analysis at 3000x and 10000x magnification revealed similar wear patterns across all biodiesel samples, suggesting that ester type has minimal impact on metallic structure formation.

This study examined how different feedstocks and alcohol types affect biodiesel properties and lubrication performance. Five feedstocks (palm, sunflower, rice bran, pork lard, and rapeseed) were transesterified using methanol and ethanol, followed by comprehensive analysis of their properties and lubricity characteristics according to ASTM standards and ISO 12156–1. Gas chromatography revealed distinct fatty acid profiles across feedstocks, with unsaturated fatty acids ranging from 53.4 % to 91.1 %. Ethyl esters demonstrated 5.47–16.65 % higher kinematic viscosity but improved lubrication properties compared to methyl esters, showing up to 13.9 % smaller wear scar diameters and 4–25 % shallower wear depths in high-frequency reciprocating rig (HFRR) tests. Notably, biodiesels from feedstocks with higher polyunsaturated fatty acid content, particularly sunflower (58.7 %), exhibited superior lubricity with wear scar diameters of 150–156.5 μm. While ethyl esters showed better lubrication, methyl esters demonstrated 0.42–0.80 % higher density and 1.92–5.88 % higher heating values. Surface analysis at 3000x and 10000x magnification revealed similar wear patterns across all biodiesel samples, suggesting that ester type has minimal impact on metallic structure formation.

Air pollution has been broadly concerned as a global issue in all regions. Particulate matter (PM) emission mainly originated from the combustion of diesel engine in transport sector is progressively solved for mitigation. The purpose of this study is to preliminary utilize biodiesel from different feedstock as an alternative fuel in a diesel engine. Waste-derived biodiesel was prepared from waste cooking oil (WCOME) and waste chicken oil (CKOME) by transesterification process. Palm oil-derived biodiesel (POME) was also prepared and used as a reference. Fatty acid profiles of the prepared biodiesel were characterized by a gas chromatography–mass​ spectrometer. The biodiesel was analyzed for fuel characteristics under ASTM standards. The engine test was carried out on a single-cylinder diesel engine at the engine speed of 1500 rpm with full engine load. The engine combustion and performance as well as exhaust emissions of waste-derived biodiesel were compared with palm oil biodiesel and diesel fuel. The PM oxidation temperature was indicated by a simultaneous thermal analyzer. The obtained results disclosed that main fatty acids of POME and CKOME were palmitic acid (C16:0) and oleic acid (C18:1) while that of WCOME were oleic acid (C18:1) and linoleic acid (C18:2). It was evident that kinematic viscosity, specific gravity and flash point of biodiesels were above the limit prescribed by the diesel fuel standard. Lubricity of all biodiesels was bounded by the limitation of diesel specification. CKOME possessed excellent lubricating properties among biodiesels tested. The combustion of WCOME lowered CO, HC and smoke emissions compared to POME while the combustion of CKOME produced similar CO, HC and smoke emissions with more benefit in NOxemissions compared to POME. PM emissions caused by the combustion of biodiesel derived from WCOME and CKOME tended to oxidize easier than those of diesel fuel because the lower temperature for maximum soot oxidation by thermo-gravimetric analysis was obtained. Consequently, biodiesel derived from waste cooking oil and waste chicken oil can be considered as potential candidates to replace the biodiesel derived from palm oil as main feedstock of biodiesel production in Thailand without any penalty in exhaust emissions.

Air pollution has been broadly concerned as a global issue in all regions. Particulate matter (PM) emission mainly originated from the combustion of diesel engine in transport sector is progressively solved for mitigation. The purpose of this study is to preliminary utilize biodiesel from different feedstock as an alternative fuel in a diesel engine. Waste-derived biodiesel was prepared from waste cooking oil (WCOME) and waste chicken oil (CKOME) by transesterification process. Palm oil-derived biodiesel (POME) was also prepared and used as a reference. Fatty acid profiles of the prepared biodiesel were characterized by a gas chromatography–mass​ spectrometer. The biodiesel was analyzed for fuel characteristics under ASTM standards. The engine test was carried out on a single-cylinder diesel engine at the engine speed of 1500 rpm with full engine load. The engine combustion and performance as well as exhaust emissions of waste-derived biodiesel were compared with palm oil biodiesel and diesel fuel. The PM oxidation temperature was indicated by a simultaneous thermal analyzer. The obtained results disclosed that main fatty acids of POME and CKOME were palmitic acid (C16:0) and oleic acid (C18:1) while that of WCOME were oleic acid (C18:1) and linoleic acid (C18:2). It was evident that kinematic viscosity, specific gravity and flash point of biodiesels were above the limit prescribed by the diesel fuel standard. Lubricity of all biodiesels was bounded by the limitation of diesel specification. CKOME possessed excellent lubricating properties among biodiesels tested. The combustion of WCOME lowered CO, HC and smoke emissions compared to POME while the combustion of CKOME produced similar CO, HC and smoke emissions with more benefit in NOxemissions compared to POME. PM emissions caused by the combustion of biodiesel derived from WCOME and CKOME tended to oxidize easier than those of diesel fuel because the lower temperature for maximum soot oxidation by thermo-gravimetric analysis was obtained. Consequently, biodiesel derived from waste cooking oil and waste chicken oil can be considered as potential candidates to replace the biodiesel derived from palm oil as main feedstock of biodiesel production in Thailand without any penalty in exhaust emissions.

AbstractAn oleaginous yeast Rhodotorula paludigena CM33 was pyrolyzed for the first time to produce bio-oil and biochar applying a bench-scale reactor. The strain possessed a high lipid content with the main fatty acids similar to vegetable oils. Prior to pyrolysis, the yeast was dehydrated using a spray dryer. Pyrolysis temperatures in the range of 400–600 °C were explored in order to obtain the optimal condition for bio-oil and biochar production. The result showed that a maximum bio-oil yield of 60% was achieved at 550 °C. Simulated distillation gas chromatography showed that the bio-oil contained 2.6% heavy naphtha, 20.7% kerosene, 24.3% biodiesel, and 52.4% fuel oil. Moreover, a short path distillation technique was attempted in order to further purify the bio-oil. The biochar was also characterized for its properties. The consequence of this work could pave a way for the sustainable production of solid and liquid biofuel products from the oleaginous yeast.

AbstractAn oleaginous yeast Rhodotorula paludigena CM33 was pyrolyzed for the first time to produce bio-oil and biochar applying a bench-scale reactor. The strain possessed a high lipid content with the main fatty acids similar to vegetable oils. Prior to pyrolysis, the yeast was dehydrated using a spray dryer. Pyrolysis temperatures in the range of 400–600 °C were explored in order to obtain the optimal condition for bio-oil and biochar production. The result showed that a maximum bio-oil yield of 60% was achieved at 550 °C. Simulated distillation gas chromatography showed that the bio-oil contained 2.6% heavy naphtha, 20.7% kerosene, 24.3% biodiesel, and 52.4% fuel oil. Moreover, a short path distillation technique was attempted in order to further purify the bio-oil. The biochar was also characterized for its properties. The consequence of this work could pave a way for the sustainable production of solid and liquid biofuel products from the oleaginous yeast.