Vegetable Oil Droplets Research Articles

Experimental study of vegetable oil droplets vaporization under low temperature conditions such as those found in diesel engine cold parts

This paper presents an analysis of three vegetable oil droplets vaporization process in the range temperature from 473 to 723 K corresponding to low temperature conditions found in diesel engine cold parts. This process is analyzed for a droplet evaporating in a hot environment at atmospheric pressure using the fiber-suspended droplet technique well used in the literature, and analyzing the droplet normalized square diameter and temperature evolution surrounding the droplet when vaporizing. The main difference between those already studied in literature is the range temperature which varies between 473 and 723 K in which vegetable oils vaporizing problems leading to deposits formation in the cold regions of diesel engines especially in direct injection. This presents a scientific challenge for resolving deposit formation. The findings reveal that vegetable oil droplets experience expansion and heating for temperatures below 623 K: no other changes are observed. Between temperatures of 623 and 683 K, an increase in temperature, expansion, and an inconsistent vaporization is observed. This is followed by a phase of low and constant vaporization. From 683 K, vegetable oils experience an initial stage of heating and expansion, which is accompanied by a phenomenon of puffing and bursting. Finally, in the last phase, residue formation occurs. Puffing and bursting phenomena manifest once the temperature reaches 683 K, indicating the emergence of substantial quantities of light compounds including carboxylic acids, aromatics, acrolein, ketene, and fatty acids. These compounds are formed through the thermal degradation and polymerization of vegetable oils. This process causes deposits to form in the colder areas of diesel engines.

Grafting–inspired bionic hierarchical structure for efficiently enhancing cemented carbide tool performance in green turning

Constructing bionic hierarchical structure on tool surface is an effective method for enhancing tool performance in vegetable oil-based minimum quantity lubrication (VMQL) assisted turning. Taking the features of VMQL assisted turning into account, the bionic hierarchical structure is expected to possess high durability and superoleophobicity. In this way, the structure function can be efficiently maintained and the vegetable oil droplets can be fully utilized. This work explored a novel grafting–inspired bionic hierarchical structure (GBHS) on cemented carbide tool surface. The agriculture technique named grafting provided inspiration for fusing the bionic structures obtained by examining dung beetle and lotus leaf. Two kinds of GBHS, namely VDGS and VAGS, were acquired due to the changes of the diameter Dc of the bionic circular recessed microstructure and the laser processing angle Al. Morphology, wetting behavior, durable superoleophobicity, mechanism and green turning performance were analyzed for GBHS. It was verified that GBHS integrated the advantages of the bionic structures of different scales and weakened the shortcomings of them. VDGS and VAGS separately exhibited highly durable low-adhesive superoleophobicity and highly durable high-adhesive superoleophobicity when they were subjected to mechanical load and high temperature. The use of VAGS prepared at the laser angle Al of 60° caused the best machining results in short-time turning. VDGS with a diameter Dc of 360 µm can be employed to acquire the optimum machining results in long-time turning. The construction strategy of GBHS can be extended to other tool materials and green machining conditions for obtaining enhanced tool performance.

Self-Lubricating and Shape-Stable Phase-Change Materials Based on Epoxy Resin and Vegetable Oils.

Palm or coconut oil is capable of dissolving in a mixture of bisphenol A-based epoxy resin and a high-temperature hardener (4,4'-diaminodiphenyl sulfone) when heated and then forms a dispersed phase as a result of cross-linking and molecular weight growth of the epoxy medium. Achieving the temporary miscibility between the curing epoxy matrix and the vegetable oil allows a uniform distribution of vegetable oil droplets in the epoxy medium. This novel approach to creating a dispersed phase-change material made a cured epoxy polymer containing up to 20% oil. The miscibility of epoxy resin and oil was studied by laser interferometry, and phase state diagrams of binary mixtures were calculated according to theory and experiments. A weak effect of oil on the viscosity and kinetics of the epoxy resin curing was demonstrated by rotational rheometry. According to differential scanning calorimetry and dynamic mechanical analysis, the oil plasticizes the epoxy matrix slightly, expanding its glass transition region towards low temperatures and reducing its elastic modulus. In the cured epoxy matrix, oil droplets have a diameter of 3-14 µm and are incapable of complete crystallization due to their multi-component chemical composition and non-disappeared limited miscibility. The obtained phase-change materials have relatively low specific energy capacity but can be used alternatively as self-lubricating low-noise materials due to dispersed oil, high stiffness, and reduced friction coefficient. Palm oil crystallizes more readily, better matching the creation of phase-change materials, whereas coconut oil crystallization is more suppressed, making it better for reducing the friction coefficient of the oil-containing material.

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.

Optimisation on the Performance of Bubble-Bursting Atomisation for Minimum Quantity Lubrication with Vegetable Oil Using Computational Fluid Dynamics Simulation

Sustainable and green machining technologies have become a welcomed topic in the manufacturing industries. One of the emerging sustainable technologies is minimum quantity lubrication (MQL). In this study, the optimisation and study of the bubble-bursting atomisation system applied to MQL machining is carried out through the computational fluid dynamics (CFD) simulation approach. Vegetable oil is selected as the cooling lubricant in this study. The performance of the bubble-bursting atomisation system is improved by alternating air inlet velocity and the gap distance between the inlets of bubble production. A velocity of 0.1 ms−1 is suitable for the air at the inlets for the bubble production, whereas 10 ms−1 is suitable for the velocity of the air at the inlet, where the droplets of vegetable oil are guided to the nozzle. Besides that, a 50 mm gap distance between the air inlets for the production of bubbles is able to avoid the occurrence of bubble coalescence. Under these conditions, optimal bubble sizes of 2–3 mm can be achieved, with a higher probability of nano-sized droplets being present in these ranges. Furthermore, a higher rate and smaller size of vegetable oil droplets escaping the atomisation chamber and reaching the machining zone will be generated. Thus, the performance of the MQL machining can be improved.

The role of 1.8-cineole addition on the change in triglyceride geometry and combustion characteristics of vegetable oils droplets

The use of Crude Vegetable Oils (CVO) in diesel engine faces several problems related to viscosity and combustion characteristics. This research aims to reveal the role of 1.8-cineole on performance characteristics of vegetable oil droplets. In this study, bubble growth, ignition delay, micro-explosion, and flame evolution process with and without 1.8-cineole in CVO has been studied experimentally at atmospheric pressure and room temperature. Droplets are examined using classical high-speed imaging techniques. The result shows that 1.8-cineole decreases all the various ignition delay into uniform time delay except for the non-polar Crude Jatropha Oil (CJO) compounds are more saturated, larger molecule and stiffer. Magnetic field produced in aromatic ring of 1.8-cineole assisted by strong electric chard in its oxygen atom induces electron in fuel molecules to become more reactive. Moreover, the 1.8-cineole compound crooked the molecular chain of triglyceride on Crude Coconut Oil (CCO), Crude Palm Oil (CPO), and Crude Sunflower Oil (CSFO) to bend apart from each other even longer, when compared to that of CJO, therefore, lowering viscosity and increasing volatility and increasing the burning rate. The polarity of the four droplets has high impact on the influence of 1.8-cineole on the performance of oil droplets in the process of evaporation to the ignition.

Oil mist concentration and machining characteristics of SiO2 water-based nano-lubricants in electrostatic minimum quantity lubrication-EMQL milling

• SiO 2 nano-lubricant droplets presented better chargeability and more likely to be affected by electrostatic force to adsorb and deposit. • SiO 2 nano-lubricant showed higher penetrability after charging compared with vegetable oil. • The adsorption quantities of the charged SiO2 nano-lubricant droplets were larger than those of the charged vegetable oil droplets. • SiO 2 nano-lubricant EMQL showed much lower oil mist concentration and alternative machining performance of traditional oil-based MQL. Minimum quantity lubrication (MQL) machining is an advanced near dry cutting technology in modern machining field. However, the cutting oil mist produced during the process of oil-based MQL affected the ambient air quality and endangered the health of employees. To avoid this drawback, a novel lubrication/cooling method called electrostatic minimum quantity lubrication (EMQL) which used SiO 2 water-based nano-lubricant as cutting fluid was proposed. The charge mass ratio, surface tension and contact angle of SiO 2 water-based nano-lubricant and vegetable oil with different charging voltages were compared, and the penetration performance of these two lubricants was analysed using capillary dynamics equation. The adsorption and deposition properties of oil mist produced by different lubrication methods were investigated, and revealed the adsorption and deposition mechanisms of the charged droplet. The influences of the charging voltage, flow rate, air pressure, spindle speed and cutting depth on PM10 and PM2.5 concentrations under different lubrication conditions were revealed. Finally, the milling performance of SiO 2 water-based nano-lubricant EMQL of stainless steels was evaluated comparatively. The results showed that SiO 2 water-based nano-lubricant presented better chargeability compared with vegetable oil, and thus displayed stronger penetrability, adsorption and deposition capacity. SiO 2 water-based nano-lubricant EMQL with -4 kV showed the lowest oil mist concentration and similar machining performances compared with the vegetable oil MQL, and the concentration values were close to the standards set by the National Institute for Occupational Safety and Health (NOISH). The charged SiO 2 water-based nano-lubricant droplets with excellent charging performance presented better adsorbability and penetrability, so that the charged droplets were prone to be electrostatic adsorbed in the machine tool and penetrated into the cutting region, which reduced the oil mist content in the machining environment and presented alternative cutting performance.

Surface Behavior of AISI H13 Alloy Steel Machining under Environmentally Friendly Cryogenic MQL with PVD-Coated Tool

Abstract Cooling and lubrication throughout the machining process have a vital impact on final product quality. Use of cutting fluid in the machining process will not control the increased heat generation that is due to frictional resistance, conventionally. Cryogenic machining along with minimum quantity lubrication (CMQL) is a reliable choice to flood cooling in pertinence. It averts the utilization of a large amount of cutting oil and it improves surface integrity. Carbon dioxide provides better cooling to the tool and work material. Additionally, the vegetable oil droplets provide better lubrication at the interface. The investigation results on the response of CMQL on machinability of AISI H13 steel with varying cutting speeds in the range of 45–75 m/min in end milling uses a PVD-AlTiN–coated carbide insert at a constant depth of cut. Machining with CMQL gives 52–53 % and 38–41 %, 65–71 %, and 33–41 % on cutting temperature and surface roughness, respectively, which is a dwindling value when interrelated with dry and flooded cooling environments, in which cutting forces and flank wear were subsequently reduced moderately when compared to dry and wet machining. Application of CMQL provides exceptional lubrication and cooling to the cutting zone.

Experimental Investigation on Combustion Characteristics of Refine Corn Oil with Areca Catechu Extract as Additive

The need for vegetable oils as alternative energy reserves increases with the depletion of fossil energy sources. Vegetable oil is the strongest candidate to replace the fossil energy. However, the use of vegetable oil directly as fuel is limited by high viscosity. Viscosity like this results in non-ideal atomization, challenging to evaporate, and cannot burn completely. Among the methods that have been studied by previous researchers and which have proven to be effective, cheaper, and can reduce the viscosity of vegetable oils better is the mixing method. In this study, corn oil was mixed with areca extract as an additive. Areca extract contains polyphenols which are polar types of epicatechin. Epicatechin has three aromatic rings and several hydroxyl groups. Delocalisation of electrons in aromatic rings can produce London forces on vegetable oil molecules, thereby increasing the reactivity of burning vegetable oil droplets. The burning characteristics of corn vegetable oil affected by areca extract have been studied experimentally at room temperature and atmospheric pressure. The results showed that the rate and temperature of combustion increased, as well as the presence of micro explosions. The London force that appears causes the bonds in the triglyceride molecules to weaken so that the combustion becomes reactive, the rate of heat transfer in the droplets gets better, facilitates the appearance of micro explosions and increases the combustion temperature. Vegetable oil from corn has been studied experimentally at atmospheric pressure and room temperature. The results show an increase in the rate of combustion, an increase in combustion temperature, and the presence of micro explosions. London force that appears causes the bonds in the triglyceride molecules to weaken so that combustion becomes more reactive, the rate of heat transfer in the droplet gets better, facilitates the appearance of micro explosions and raises the combustion temperature.

Experimental investigation on the evaporation and micro-explosion mechanism of jatropha vegetable oil (JVO) droplets

The present study mainly focused on the evaporation and micro-explosion mechanism of jatropha vegetable oil (JVO) droplets. Six major components of JVO and their blends were investigated at ambient temperature of 873 K and 1073 K under normal gravity. The properties of JVO were analyzed by TG-DSC (thermogravimetric-differential scanning calorimetry) analysis and LC–MS (liquid chromatograph mass spectrometer). The results show that the evaporation process of JVO droplets are different from that of single component fatty acids and their blends at temperatures of 873 K and 1073 K. No micro-explosions occurred during the whole evaporation progress of single fatty acids and their blends at 873 K, while the intense and repeating micro-explosions occurred in JVO droplet evaporation process at 873 K and 1073 K. In addition, steam “Clouds” were observed during the JVO evaporation process of 873 K and 1073 K. Importantly, cracking reaction will occur in the JVO evaporation process, these gas products come from heavy component (triglyceride molecule) cracking and boiling of liquid products lead to repeating micro-explosions and totally different evaporation characteristics.

The effect of fatty acid polarity on the combustion characteristics of vegetable oils droplets

The effect of fatty acid polarity on the combustion characteristics of vegetable oils droplets, CCO and CJO vegetable oil droplets have been studied experimentally with atmospheric pressure and room temperature. The role of intermolecular forces on the combustion characteristics of vegetable oils droplets. CCO and CJO are multicomponent vegetable oils, CCO represents saturated fatty acids while CJO represents monounsaturated fatty acids. The results showed that the burning rate of vegetable oil was influencing by the polarity of the fatty acids that compose it. CCO is dominated by polar fatty acids which shows a stable flame and around a flame shape. CJO which is dominated by non-polar fatty acids the results show an increase in the rate of combustion, the presence of microexplosion and the form of an elongated flame. The large CCO polarity causes the CCO to be more reactive, fast ignition of round and stable flame forms. The small CJO polarity causes the CJO molecules to be less reactive and slow to ignite. the shape of the flame on CJO extends upwards with microexplosion while in the CCO the way of the round flash. This is because of the different fatty acid content and geometry in each vegetable oils.

Role of Intermolecular Forces on the Contact Angle of Vegetable Oil Droplets during the Cooling Process.

This study aims to experimentally determine the role of intermolecular forces on the contact angle of vegetable oil droplets. Contact angles were recorded using a microscope and measured using digital software. The results show that the surface tension of vegetable oils is influenced by the London force between the electron clouds of molecules. The process of cooling increases vegetable oil contact angles, due to the decreased kinetic energy of constituent molecules and increased London force on the molecules. A decrease in temperature causes the surrounding water vapor to condense, which adheres to the droplet surface (due to the hydrophilic properties of molecules). Hydrogen bonds develop after moisture adheres to the surface. Further, water molecules on the droplet surface reduce the surface tension, because of hydrogen bonds between the molecules on the droplet surface and moisture. Hydrogen bonds among the molecules force water molecules to accumulate on the droplet surface, which suppresses the droplet surface; therefore the contact angle decreases.

The effect of Rh3+ catalyst on the combustion characteristics of crude vegetable oil droplets

The effect of Rh3+ catalyst on the combustion of the Crude Vegetable Oil droplet, namely coconut, jatropha, and sunflower oil has been studied experimentally at atmospheric pressure and room temperature. The oil droplets contain multi-component elements that are saturated fatty acid, monounsaturated fatty acid, polyunsaturated fatty acid, and glycerol. Results demonstrated that the catalyst has a stronger influence on crude coconut oil (CCO) and crude sunflower seed oil (CSFO) polar compounds during combustion, indicated by a greater enlargement of their triglyceride chains relative to those in crude jatropha oil (CJO). The changes in triglyceride geometry were identified as the cause of the distinguishing CVO droplet combustion characteristics. During the heating process preceding ignition, internal evaporation occurs with the appearance of bubbles trapped in oil droplets, and it appears that the diameter of the CJO droplet is greater than that of CCO and CSFO. This result suggests that the non-polar CJO compounds are more saturated, requiring additional heat for evaporation and ignition. The results also show that the catalyst makes multi-step burning droplets becomes shorter in one stage with the highest burning temperature. This proves that the catalyst does not only enlarge the triglyceride geometry but also excites the electrons due to hydrogen atom attraction as well.

The Effect of Atmospheric Oxygen on the Puffing and Bursting Phenomena during Vegetable Oils Droplets Vaporization Process for Their Use as Biofuel in Diesel Engine

The past literature on the use of vegetable oils as fuel in diesel engine revealed that utilizing vegetable oil fuels in diesel engines may require property changes in the oil or perhaps, some minor engine modifications or operating changes. This study was conducted to search for the effect of atmospheric oxygen on the puffing and bursting phenomena that occur during vegetable oils droplet vaporization process in their use as fuel in diesel engine. The fiber-suspended droplet technique was used, and the normalized square droplet diameter as well as the temperature evolution vicinity the droplet was analyzed. The results show that puffing and bursting phenomena highly depend on oxygen. In presence of atmospheric oxygen, there is an increase of the puffing and bursting intensity and therefore the evaporation rate of the vegetable oil droplets, but in an inert environment or when the environment is oxygen-depleted puffing and bursting phenomena disappearing and make place of a series of explosions with lower magnitude. The lack of oxygen reduces the thermal degradation, polymerization and oxidation reactions and consequently the vaporization rate of vegetable oils droplets; and could therefore lead to the formation of deposits in the form of polymers. This is unsuitable for their use as a fuel in diesel engines. It can also be concluded that atmospheric oxygen has some positive effects on engine performance and emissions when operating with vegetable oil. These results help to address the challenge for the use of alternative fuels such as non-edible vegetable oils.

Experimental study on puffing and evaporation characteristics of jatropha straight vegetable oil (SVO) droplets

The present investigation studied the puffing characteristics and evaporation characteristics of jatropha straight vegetable oil (SVO) droplet under high ambient temperature in the experiments of single droplet evaporation. The effects of temperature on droplet normalized squared diameter and evaporation phenomenon were analyze. The results show that the evaporation characteristics of jatropha SVO droplet at 873 K are completely different from that at 673 K. The evaporation of jatropha SVO can be divided into three phases: transient heating phase, fluctuation evaporation phase and equilibrium evaporation phase. Puffing can be observed at both 673 K and 873 K; and, at 873 K, droplet deformation, bubble formation and expansion, jet and micro-explosion are also observed in the evaporation process. The increase of the ambient temperature is the main reason for improving the evaporation of jatropha SVO droplet, it is because there are many high volatile components in jatropha SVO which will first volatile to form bubbles and then make droplet puffing and micro-explosion under high temperature.

Gelatin-Based Emulsion Gels for Diffusion-Controlled Release Applications

Emulsion gels are now emerging as a new class of biomaterials for controlled-release applications. Novel food-grade emulsion gels consisting of indomethacin-loaded vegetable oil droplets dispersed within genipin-cross-linked gelatin-based hydrogels were characterized for their physical and drug-release properties. Varying the weight ratio of the aqueous and oil phases between 5:1 and 5:5 was used to modulate construct swelling and drug release. The dispersed oil droplets generally became larger, more polydispersed and aggregated with an increase in oil fraction. Cross-linking with genipin increased the puncture strength of the gels vs. their uncross-linked counterparts and was necessary to prevent breakdown. Swelling of the emulsion gels demonstrated Fickian behaviour at all gelatin: oil ratios. Indomethacin release followed Fickian diffusion at higher oil fractions only, demonstrating coupled Fickian and super-Case-II transport at lower oil ratios (5:1, 5:2 and 5:3). Overall, the introduction of a dispersed oil phase within a hydrogel was exploited for the release of hydrophobic bioactive compounds, with tailoring of composition used to significantly alter release kinetics.

Droplet vaporisation characteristics of vegetable oil derived biofuels at high temperatures

Abstract To characterise the mechanisms occurring in the deposit formation during the combustion of vegetable oils used as biofuels in Diesel engines, it is necessary to investigate the vaporisation of vegetable oil droplets under various flow, pressure and temperature conditions. In the current work, experimental results about the vaporisation of rapeseed and sunflower oil methyl ester droplets at high temperatures are presented. The fibre-suspended droplet technique is used and the time evolution of droplet diameter during vaporisation is observed by imaging technique. Average and instantaneous vaporisation rates have been estimated from the d 2 -curves at temperatures between 473 and 1020 K and at atmospheric pressure. The droplets of vegetable oil methyl esters evaporate like mono-component droplets with a very significant heating phase. A comparison with experimental results obtained with n -alkanes droplets (from n -pentane to n -decane) and prediction of the quasi-steady theory is also presented and discussed.

The manufacture of set-type natural yoghurt containing different oils — 2: Rheological properties and microstructure

Abstract Yoghurts rich in poly- and mono-unsaturated fatty acids were manufactured from reconstituted skimmed milk powder using vegetable oils (olive, groundnut, sunflower or maize) to replace the milk fat. They were compared with a yoghurt-containing anhydrous milk fat [AMF, 1.5% ( w w )]. The vegetable oil-based yoghurts [at a 1.5% ( w w ) level of addition] were different from the control yoghurt containing AMF. Whey separation was higher and firmness was lower for all vegetable oil-containing yoghurts than for the product containing AMF. Scanning electron microscopy revealed similar microstructure, including the distribution of void spaces filled with milk serum (porosity of the protein matrices), whereas transmission electron microscopy showed the interaction of the vegetable oil droplets with casein micelles and their participation in the formation of the gel matrices.