Oil Film Formation Research Articles

Management of Waste Cooking Oil and its Potential for Value-added Materials: A Mini Review

Improper management of waste cooking oil in food industries like restaurants, hotels, and the use of retort technology in food processing is causing a devastating impact towards the environment. This is observed through odor problems and oil film formation on the surface of water bodies that increases the biological oxygen demand. Additionally, different types of cooking oil represent different physicochemical properties. This allows for the potential use of waste cooking oil as a carbon source for fungal growth thus contributing to the production of value-added products at a low cost and eco-friendly process. Biodegradation may take place by the enzymatic reaction which involves the hydrolysis of triglycerides and metabolized through the β-oxidation pathway to acetyl-CoA. Many fungal and bacterial strains capable of degrading vegetable cooking oils have been reported with most from the genus Aspergillus, Pseudomonas, Enterobacter, and others. From the industrial perspective, with the correct technology and proper recycling technique, waste cooking oil can be readily utilized as chemical building blocks in lubricant, candle, and fuel productions.

Study on Lubricating Performance of Soft Slider Bearing in Conformal Contact

ABSTRACTIn this paper, the lubricating performance of soft slider bearing in conformal contact is analyzed. Compared with the hard slider, the soft slider will have greater elastic deformation under low pressure. Three kinds of sliders with different elastic modulus are used for comparative study in this paper. The materials of the three sliders are: steel, glass and PMMA. A hydrodynamic lubrication model of conformal contact considering elastic deformation is established according to the theory of fluid lubrication. A program for calculating dynamic pressure lubrication performance of conformal contact considering elastic deformation is developed by using Matlab and Comsol. The influence of different inclination, different speed and different load on hydrodynamic lubrication performance was studied respectively. The results show that under the same conditions, the elastic deformation on the surface of the slider is more conducive to the formation of oil film, and more conducive to the conditions of high load.

Effects of current-carrying conditions on lubrication and tribological performance of ionic liquid

Ionic liquids are considered to be ideal electronically controlled friction and lubrication media because of their excellent lubrication and electrical conductivity. However, systematic research on the lubrication performance and friction principles of ionic liquids under current-carrying conditions is lacking. In this study, the lubrication and friction properties of an ionic liquid under different carrying-current conditions and the effect of addition of Fe3O4 nanoparticles on its tribology were investigated using a current-carrying friction and wear tester and analyzed in detail. The experimental results showed that the lubricating ability of the ionic liquid improved under lower current intensity conditions, resulting in a slight decrease in the friction coefficient between the friction pairs. However, as the current intensity increased, the ionic liquid lubrication adsorption film was destroyed by the current breakdown, resulting in a significant increase in the friction coefficient between the friction pairs. These phenomena suggest that the friction and lubrication performance of the ionic liquid could be actively controlled by applying a current. Simultaneously, the addition of Fe3O4 nanoparticles further improved the friction enhancement effect of the ionic liquid under a high current intensity. These effects were related to the controlled formation and failure of the ionic liquid lubrication adsorption oil film under the current-carrying conditions.

Influence of the Synergistic Effect of Multi-Walled Carbon Nanotubes and Carbon Fibers in the Rubber Matrix on the Friction and Wear of Metals during the Mixing Process.

As a piece of high-intensity running equipment, the wear of an internal mixer determines the quality of rubber and its life. In general, the wear of an internal mixer is caused by the friction between the rubber and metal during the mixing process, and the most severe wear position is the end face of the equipment. In this paper, a mixture of multi-walled carbon nanotubes (MWCNTs) and carbon fibers (CFs) are added to rubber by mechanical compounding to obtain MWCNT/CF/carbon black (CB) composites. By investigating the synergistic mechanism of MWCNTs and CFs, we analyze the effect of the MWCNT/CF ratio on the frictional wear of metal on the end face of the internal mixer. At the microscopic level, MWCNTs and CFs form a spatial meshwork with CB particles through synergistic interactions. The CB particles can be adsorbed on the spatial meshwork to promote the dispersion of CB particles. In addition, the formation of oil film can be slowed down due to the spatial meshwork, which could hinder the spillage of aromatic oil. Meanwhile, the spatial meshwork serves as a physical isolation layer between the rubber and metal to reduce friction. Therefore, it dramatically impacts the dispersion degree of CB particles, the friction coefficient, the roughness of the surface, and the wear of metal. It shows that the synergistic effect of MWCNT/CF and CB particles is best when the CF content of the rubber matrix is 5 phr, showing the most stable spatial network structure, the best dispersion of CB particles, and minor wear on the end face of the internal mixer.

Evolution of oil film formation in the bearing radial bearing housings

Slip bearings are machine components that provide support for rotating parts, usually rotating shafts or axles, take on the forces that load the parts concerned and work under conditions of relative sliding of the shaft journal surface onto the bearing (bearing shell) surface, while the two surfaces are separated by a film of lubricant. For the correct operation of the slip bearings, without systematic wear of the Journal and bearing shell surfaces, they must be separated by a sufficiently thick lubricant film to completely exclude direct contact of the two surfaces in relative movement.

Experimental investigation of dynamic behavior of rotor system with a novel double layers flexible support tilting pad bearing

Among all kinds of journal bearings, the tilting pad bearing has the characteristics of high stability. In order to further reduce the vibration and improve the stability of rotor-bearing systems, a novel double layers flexible support tilting pad bearing (DL-FSTPB) is presented in this paper. The bearing utilizes two layers of springs, which have different functions. The offset springs control the swing angle of the tilting pad to ensure the formation of a convergent oil film, and the symmetrical springs are used to change the bearing stiffness coefficient, increase the bearing elasticity, and improve the ability to accommodate misalignment. Experiments were carried out to study the vibration characteristics of the rotor system. The results were analyzed using wavelet analysis of acceleration and displacement, waterfall plots, a wavelet analysis, a run-up process and shaft center orbits areas. The results show that the DL-FSTPB exhibits excellent vibration attenuation characteristics, which can effectively reduce the amplitude and the system vibration level.

Preparation and tribological properties of TiH2/Fe-based oil-containing materials with interconnected pore structures

To build an interconnected system of pores for oil storage, a ball milling (BM) strategy that disperses TiH2 homogeneously within iron-based composites was developed. TiH2/Fe powders were pressed and sintered after ball milling at 250 r/min. Special consideration was given to the effects of the BM duration on the microstructural and tribological properties of the materials. Tribological behavior was evaluated using the rotatory sliding and incremental loading tests. Specimens were characterized before and after testing via optical microscopy and scanning electron microscopy. The results showed that the materials produced via BM offer remarkable lubrication properties. An interconnected pore structure seems to be conducive to the formation of a lubricating oil film that effectively improves friction and wear resistance.

Hidrodinamik radyal kaymalı yataklarda yüzey pürüzlülüğünün sürtünme davranışları üzerindeki etkilerinin incelenmesi

In hydrodynamic plain bearings, parameters such as friction coefficient, oil film thickness, pressure distribution, oil flow, etc. are very important design criteria in terms of bearing design and optimum energy efficiency. In this study, in order to investigate the effects of surface roughness on bearing performance in hydrodynamic plain bearings, experiments were carried out at different loads and temperatures using two bearing envelopes with the same bearing material and with different surface roughness. As a result of the experiments, it was determined that the surface roughness was more effective especially in the boundary and mixed friction region than in the fluid friction region. It was determined that while the oil film formation ability decreased with increasing surface roughness, wear and power loss in the bearing increased.

Influence of multi-walled carbon nanotubes (MWCNTs) content on metal friction and wear in thermally cracked carbon black (CBp) formulation system during mixing

As the essential mixing equipment, long hours of work can cause wear and tear on the end face of the compactor. The wear of the end faces leads to an increase in the gap between the chamber and the end faces, which leads to leakage, reduces the mixing effect, and ultimately affects the rubber properties. Therefore, it is necessary to study the end face metal wear during the mixing process. Thermally cracked carbon black, as recycled material for scrap rubber, can be used as a substitute for other carbon blacks in some fields, vastly reducing the production cost and promoting the reuse of scrap rubber. In this paper, thermally cracked carbon black (CBp) was mixed with multi-walled carbon nanotubes (MWCNTs) and added rubber by mechanical blending to obtain CBp/MWCNTs composites. The synergistic mechanism of CBp and MWCNTs was investigated to analyze the effect of CBp/MWCNTs ratios on the frictional wear of metal on the end face of the compactor. The results showed that MWCNTs cooperated with CBp particles to form a three-dimensional “grape bunch” network structure. On the one hand, the three-dimensional “grape bunch” network structure can adsorb CBp particles to promote the dispersion of CBp particles. On the other hand, the three-dimensional “grape bunch” network structure can also hinder the overflow of aromatic oil and affect oil film formation. At the same time, the three-dimensional “grape bunch” network structure can also form a physical isolation layer between the rubber and the metal. This significantly influences the degree of CBp particle dispersion, friction coefficient, metal surface roughness, and metal wear. It seems that the synergistic effect between MWCNTs and CBp particles is maximized when the content of MWCNTs in CBp/MWCNTs composites is 4 phr, the area of CBp/MWCNTs three-dimensional mesh is maximized, the dispersion of CBp particles is the best, and the wear of CBp/MWCNTs composites on metal is the lowest.

Investigation of Oil–Air Flow and Temperature for High-Speed Ball Bearings by Combining Nonlinear Dynamic and Computational Fluid Dynamics Models

Abstract An improved nonlinear dynamic model of high-speed ball bearings with elastohydrodynamic lubrication is adopted to predict the movements of balls and power loss of ball bearings for defining the boundary conditions of a computational fluid dynamics (CFD) model. Then, this method of combining nonlinear dynamic and CFD models is validated through the experimental verification. Subsequently, oil–air flow and temperature distribution inside the bearing chamber are studied at low and high speeds and light and heavy loads. The effect of nozzle’s position on the formation of oil film and heat dissipation is revealed under combined loads. The research results provide a theoretical basis for engineering application of high-speed rolling bearings.

Cobalt (II) used as a catalyst to drying properties of healing agents for self-healing coatings / Cobalto (II) utilizado como catalisador de propriedades de secagem de agentes de cura para revestimentos auto-regenerativos

Vegetable oils have been largely used as healing agents for self-healing coatings, which in turn, can recover their physical integrity upon damage due to oil film formation resulted of its oxidative polymerization process. Linseed oil (LO) and chia oil (CO) are able to form films because of their air-drying properties and high polyunsaturated fatty acids content. In this work, drying properties of CO and LO with and without cobalt (II) octoate, as a catalyst for the oxidative polymerization, were quantitatively estimated over time by Fourier-Transform Infrared Spectroscopy (FTIR). The CO drying property showed 47% higher than LO and the catalyst has successfully accelerated the oxidative polymerization of both oils in 95%. Microcapsules containing both pure and catalyzed oils were prepared, mixed into epoxy resin, and applied onto AISI 1020 steel samples. Their healing effect was evaluated through a simulated scratch and submitted to electrochemical tests and imaging.

Specific Aspects in Numerical Simulation of Complex Processes in Gas Turbine Engine Bearing Chamber

The complex interrelation of thermal and hydraulic processes in a gas turbine engine bearing chamber requires modelling methods based on the multiphase flow mechanics and Computational Fluid Dynamics (CFD) to predict the fluid distribution and heat transfer phenomena. This paper presents a study of different approaches to CFD modelling of multiphase oil-air flow in the bearing chamber. The Volume of Fluid and Eulerian multiphase models, Steady and Transient solvers, “Realizable k-ε” and “k-ω SST” turbulence models were analysed. The Eulerian Wall Film Model implemented in ANSYS Fluent was applied to model an oil film formation on the bearing chamber walls. The CFD results were compared with available experimental data to formulate practical recommendations for precise modelling of processes in the bearing chamber.

An ultrasonic method for measurement of oil films in reciprocating rubber O-ring seals

In this study, ultrasound has been developed and applied for a rubber O-ring subjected to reciprocating sliding. Under varying reciprocating speeds (2–8 Hz) and normal loads (10–20 N), ultrasonic reflection from the sealing contact was measured for analyzing the oil film formation. Central film thickness measurements were found to be in the range of 1.8–7 µm, which were comparable to the modelling results. In addition, the oil film along the reciprocating path was measured using an array of ultrasound sensors; this mapped the oil film formation covering the length of the reciprocating stroke. The findings have concluded that the ultrasound technique is an effective approach in detecting the oil film formation and contact size for the sealing contact.

Effects of fluid film properties on fouling in biphasic flow systems

Flow chemistry has the potential to enhance the large-scale accessibility of precision-engineered nanomaterials. While reactor fouling presented a major challenge in precision control, the liquid–liquid segmented flow method has been demonstrated to reduce or even eliminate it. However, guidelines for properly selecting materials and designing parameters in such systems are currently lacking. For these reasons, the present study investigated two biphasic flow systems for continuous gold nanoparticle (AuNP) synthesis. Visual observations showed no evidence of fouling in the silicone oil–water flow system, but some localized fouling was observed in the heptane-water flow system. The results indicated the silicone oil–water system gave a 50% lower polydispersity index and a 25% higher reaction yield due to fouling mitigation. We investigated two important factors of the continuous phase for fouling reduction: liquid film continuity and film thickness. Film continuity was evaluated by temperature-controlled contact angle measurements and the film dewetting velocity; And film thickness was estimated using two different mathematical models. It was concluded that the formation of a continuous oil film of thickness higher than the maximum surface asperities, as was the case only for the silicone oil–water flow system, is critical to eliminate fouling in continuous AuNP synthesis.

Grindability of carbon fiber reinforced polymer using CNT biological lubricant

Carbon fiber-reinforced polymer (CFRP) easily realizes the integrated manufacturing of components with high specific strength and stiffness, and it has become the preferred material in the aerospace field. Grinding is the key approach to realize precision parts and matching the positioning surface for assembly and precision. Hygroscopicity limits the application of flood lubrication in CFRP grinding, and dry grinding leads to large force, surface deterioration, and wheel clogging. To solve the above technical bottleneck, this study explored the grindability and frictional behavior of CNT biological lubricant MQL through grinding experiments and friction-wear tests. Results showed that the CNT biological lubricant reduced the friction coefficient by 53.47% compared with dry condition, showing optimal and durable antifriction characteristics. The new lubrication was beneficial to suppressing the removal of multifiber block debris, tensile fracture, and tensile-shear fracture, with the advantages of tribological properties and material removal behavior, the tangential and normal grinding force, and the specific grinding energy were reduced by 40.41%, 31.46%, and 55.78%, respectively, compared with dry grinding. The proposed method reduced surface roughness and obtained the optimal surface morphology by preventing burrs, fiber pull-out, and resin smearing, and wheel clogging was prevented by temperature reduction and lubricating oil film formation. Sa and Sq of the CNT biological lubricant were reduced by 8.4% and 7.9%, respectively, compared with dry grinding. This study provides a practical basis for further application of CNT biological lubricant in CFRP grinding.

Effect of injection strategy on the mixture formation and combustion process in a gasoline direct injection rotary engine

A computational fluid dynamics model was established and validated to numerically investigate the effects of different injection positions and injection angles on the mixture formation and combustion process in a gasoline direct injection rotary engine. The results show that as the injection position approaches the top dead center and the increasing injection angle, the rich zone of fuel changes from the rear to the front of the combustion chamber. The local equivalence ratio near the two spark plugs shows an increasing trend with the injection position upward and the increasing injection angle. Compared with the lower and middle injection positions, the upper injection positions can make fuel more concentrated near the leading spark plug and the trailing spark plug at ignition timing. The injection strategies corresponding to the upper injection position are conducive to complete combustion, in which the mass fraction of fuel burned all beyond 99%. Besides, with the increasing injection angle, the oil film formation position changes from the rotor recess to the middle cylinder block, which further affects the mixture formation and combustion process. Especially, the highest peak pressure is obtained at 0° injection angle corresponding to the upper injection position and is 12.39% higher than the in-cylinder peak pressure of intake port injection.

Effects of lubricant on evaporation and boiling processes of R1234ze(E): A molecular dynamics study

• Boiling process of refrigerant/lubricant mixture is investigated from microscopic. • The heat transfer capacity of mixture system is evaluated by thermal resistance. • Temperature jump and thermal resistance length increase with lubricant increasing. • An oil film formed on Cu surface weakens the heat transfer capacity at interface. Lubricant plays an important role in thermodynamic systems to lubricate the sliding surfaces. However, the mixing of working fluid and lubricant will significantly affect the heat transfer capacity of the system. Therefore, molecular dynamics simulations are employed to investigate the effects of lubricant PEC4 on the evaporation and boiling processes of R1234ze(E) in this paper. The results indicate that the evaporation and boiling process of R1234ze(E) is suppressed by the addition of PEC4 molecules. Additionally, PEC4 molecules will gradually replace R1234ze(E) molecules to absorb on Cu surface with the increase of PEC4 mass fraction. Then, an oil film will be formed on Cu surface and weaken the heat transfer capacity at the fluid–solid interface. The thermal resistance length is employed to evaluate the heat transfer capacity of the system. The result shows that the increase of the mass fraction of PEC4 will lead to an increase of temperature jump and thermal resistance length, which weakens the heat transfer capacity. Moreover, the strong attractive interactions between PEC4 and Cu substrate will lead to the formation of oil film on the Cu surface during the evaporation and boiling processes, which will result in heat transfer deterioration.

Study of Injection Method for Maximizing Oil-Cooling Performance of Electric Vehicle Motor with Hairpin Winding

The oil injection method was studied to maximize the cooling performance of an electric vehicle motor with a hairpin winding. The cooling performance of the motor using the oil cooling method is proportional to the contact area of the oil and the coil. A numerical analysis was conducted to examine the effect of the spray nozzle type on the oil flow. The dripping nozzle forms the thickest oil film on the coil, making it the most effective for cooling of hairpin-type motors. Subsequently, an experimental study was conducted to optimize the nozzle diameter and number of nozzles. When the inlet diameter and number was 6.35 mm and 6, the oil film formation rate was 53%, yielding the most uniform oil film. Next, an experiment was performed to investigate the effects of the oil temperature and flow rate on the oil flow. The oil film formation rate was the highest (83%) when the oil temperature was 40 °C and the flow rate was 6 LPM.

Challenges in Formulating Sunscreen Products.

Developing efficient sunscreen products with an acceptable sensory feel after application on skin, that meet current regulatory market and consumer requirements, is a major challenge, exacerbated by new restrictions limiting the use of certain ingredients previously considered crucial. This paper outlines a development strategy for -formulating sunscreens along a generic professional development pathway. Each galenic system will be different and must be customized. Development starts with benchmarking, followed by UVA/UVB filter platform selection and in silico calculation/optimization of photoprotection performance for the desired SPF, UVA-PF, and other requested endpoints. Next comes the selection of the emulsifier system and other key formulation ingredients, such as oil components, triplet quenchers, and antioxidants, with sensory, rheological, and film formation functions. Preliminary cost estimation is then performed to -complete the conceptual process before the start of the practical galenic development. The successful development of modern sunscreen products is based on -comprehensive expertise in chemistry, galenic methodology, regulation, and patenting, as well as specific -market and consumer requirements. The selection of the UV filters is the first key decision and constrains later choices. Other properties, such as water resistance and preservation or active ingredients, may need to be considered. The 4 basic requirements of efficacy, safety, registration, and patent freedom become checklist items to ensure that after development, a sunscreen product has a chance of success.

Simulation of the oil film thickness on a friction surface in the presence of fullerene compositions in the lubricant

The paper contains theoretical studies of the oil film formation on a friction surface in the presence of fullerene solutions in a lubricant. The mathematical model is developed on the basis of the interaction between electrically active heterogeneous finely dispersed systems at the interface between the friction surface and the lubricating medium and is described by the Poisson differential equation. The role of the friction surface on the formation of clusters and micelles in an adsorbed film of the lubricant near the friction surface is established. It is shown that in the stress-strain state of triboelement material surface layers, the friction surface acts as an “electrostatic field generator”. Expressions are obtained for the simulation of the oil film thickness in the presence of fullerenes in the base lubricant. Based on the simulation results, the most significant factors in the formation of the oil film thickness have been established: these are the electric field strengths of the friction surface and the base lubricating medium; the load on the tribosystem; the temperature, and dynamic viscosity of the lubricating medium.