Low-viscosity Oil Research Articles

Durable superhydrophobic engineered mesh with self-healing and anti-corrosive capabilities for efficient oil/water separation

The complex composition of oilfield-produced water is easy to scratch or corrode the separation membrane because of the existence of solid micro-particles, corrosive acid and alkali, proposing higher requirements on the durability of the membrane. Herein, a durable self-healing stainless-steel mesh was fabricated by hydrothermal growth of Ni and Fe double hydroxide nanosheet structure and dip-coating of polydimethylsiloxane (PDMS). The coating of ultrathin PDMS on the top of the nanosheets excellently maintained roughness of surface, while the PDMS stored at the valleys of the nanosheets array acted as a supplementary source for continuous self-healing process. Therefore, the engineered mesh could self-heal its superhydrophobicity despite suffering from different scales of damage. Moreover, the prepared mesh exhibited reliable superhydrophobicity, mechanochemical durability, corrosion resistance and self-cleaning properties. Eventually, the mesh showed ultrafast flux (21,000 L m−2 h−1) and rejection rate (> 99.99%) for separating phenixin/water mixtures during 50 continuous cycles. In addition to low-viscosity oils, the engineered mesh could separate high-viscosity crude oil/water mixtures. Aiming at the practical problem that dirty oil containing solid micro-particles is difficult to separate, the three-phase separation performance of the mesh on oil/water/sand mixtures was studied. These features make the engineered mesh have great practical application potential in oilfield-produced water treatment.

Self-Assembled CMC/UiO-66-NH2 Membrane with Anti-Crude Oil Adhesion Property for Highly Efficient Oil-Water Separation.

Developing the high-anti-fouling membrane has kept continuous attention in oil/water emulsion treatment. However, the majority of works on anti-fouling membranes mainly focused on low-viscosity oils, which greatly limited the development and application of a membrane to face the real crude oil wastewater. Inspired by the hydrophilicity of sodium carboxymethyl cellulose (CMC) and zirconium base metal-organic frame (Zr-MOF), an anti-oil-fouling CMC/UiO-66-NH2 composite membrane was constructed by a self-assembly method. Profiting from the hydrophilicity and micro-nanostructure of the CMC/UiO-66-NH2 layer, the obtained CMC/UiO-66-NH2 membranes displayed underwater superoleophobicity and desired oil resistance. It could display the effective separation capability with 1282 ± 62 to 6160 ± 81 L/(m2·h·bar) and above 99.08% toward the different light oil emulsions. More importantly, the CMC/UiO-66-NH2 membrane displayed ultralow crude oil adhesion behaviors toward the crude oil emulsions, which could achieve a considerably high flux (746 ± 60 to 5224 ± 87 L/(m2·h·bar)). Furthermore, electrostatic interaction and physical enwinding-wrapping between CMC and UiO-66-NH2 also endowed the composite membranes with outstanding stability. After immersing the as-prepared membranes into the harsh environments for 24 h, the membranes still maintained high underwater-oil contact angles (UWOCA > 155°) and separation ability (oil rejection was above 99.0%). Therefore, CMC/UiO-66-NH2 composite membranes could demonstrate promising prospects in real oily emulsion treatment.

Effect of Lubricant Viscosity on Wetting Behaviors and Durability of Anti-icing Slippery Liquid-Infused Porous Surfaces

Icing accretion posed a safety hazard to power lines. Slippery liquid-infused porous surfaces (SLIPSs) are widely used in anti-icing applications. High-viscosity silicone oil has been reported to improve the durability of SLIPS. However, high viscosity can cause problems such as slow self-healing and weak mobility of water droplets on the surface. Herein, the effect of lubricant viscosity on the wetting behavior and durability of anti-icing SLIPS was investigated. The droplet shedding test was conducted to study the durability of SLIPS. The results show that low-viscosity silicone oil can make the prepared SLIPS have good lubricity and low ice adhesion strength, while high-viscosity silicone oil can improve the durability of SLIPS. Under the condition that SA does not exceed 5° and ice adhesion strength does not exceed 10 kPa, 200 cSt silicone oil can make SLIPS simultaneously exhibit excellent slipperiness and durability.

문서 감정상 볼펜 필획의 잉크 밀집도 및 너비 특성

The purpose of this study was to confirm the possibility of using the ink stroke density and width as a non-destructive analysis factor for estimating the ink and ball size of a ballpoint pen in the field of identification of writing instruments for document evaluation. The density and width of strokes were measured by applying a constant pressure (100-300 g) to a total of 39 ballpoint pens of 4 types of ink (oil, low-viscosity oil, gel and water) and ball size (0.5-1.0 mm). As a morphological characteristic of stroke density, it was confirmed that there were four types: 1) Selective diffusion of high-viscosity ink, 2) Agglomeration, 3) Dot, 4) Selective diffusion of low-viscosity ink. The deposition value of ink stroke density showed a tendency to be measured twice as low for oil (33.74~47.26%) with high viscosity compared to gel (78.19~84.66%) and water (44.96~85.26%) with low viscosity of ink. The stroke width showed a tendency to increase as the pressure applied to the ballpoint pen and the size of the ball increased. The stroke width according to the ink was similar in the case of oily and low-viscosity oils, but in the case of neutral, it was about 100 μm higher than that of oil and low-viscosity oils. As a result, the density and width of strokes showed a difference in the characteristics that appeared according to the viscosity of the ink. In the order of non-destructive analysis for the identification of writing instruments, it is necessary to ① analyze the deposit shape and deposit value of ink stroke density, and ② to estimate the ink and ball size through ink width measurement. It was confirmed that it can be used.

Emulsification of low viscosity oil in alkali-activated materials

This research aims to understand the mechanisms enhancing the fixation of low viscosity mineral oils, including tailings, in reactive inorganic matrices, by emulsification. To this purpose, significant amounts of a model low viscosity pure mineral oil (20%vol) are immobilized in alkali-activated materials (AAM), either based on metakaolin or blast furnace slag. In such case, Portland cement-based matrices are not adequate (emulsification delicate to manage and excessive setting retardation). Various surfactants are used to ease the oil emulsion.Visual observation and rheology evidence two distinct groups of surfactants. One contributes to structuring the oil/AAM fresh mix, with greater viscosity than without surfactant; the other includes non-structuring surfactants, without change in viscosity. Each group depends on the AAM considered.Whatever the AAM and the surfactant, the oil droplet size decreases significantly, without consistent correlation with the interfacial tension between oil/activating solution (AS). Interfacial tension alone does not explain the reduction in oil droplet size. Characterization of diluted ternary suspensions (solid particles – oil – AS) relates the structuring effect to interactions between oil and solid particles, through the surfactant polar head groups and non-polar hydrocarbon tails. A detailed mechanism explaining the oil stabilization and the mix structuring is discussed.

Shifts in Bacterial and Archaeal Community Composition in Low-Permeability Oil Reservoirs by a Nutrient Stimulation for Enhancing Oil Recovery

Indigenous microbial enhanced oil recovery technology by selective nutrient injection is a potential alternative that leads to oil production improvement in low-permeability oil reservoirs. Nutrient flooding in oil reservoirs can shift the balance of microorganisms within a population; an in-depth exploration of this phenomenon can enable us to selectively activate particularly beneficial microbial species for enhancing oil recovery. In this study, high-throughput sequencing was employed to analyse indigenous microorganisms (e.g., archaea and bacteria) in an oil production well (W226), compared to a control well (W202), in the Xingzichuan Oil Recovery Plant (Ansai, Shaanxi, China). According to alpha diversity analysis and community composition, the nutrient injection exhibited a significant impact on indigenous archaea at the genus level. The predominant archaeal genus Methanolobus (more than 66%) in the control well shifted to Methanocalculus (50.8%) and Methanothermococcus (30.6%) genera in the oil production well. Conversely, the activators increased bacterial community richness but reduced its evenness. Bacterial community analysis at the genus level revealed that nutrient injections significantly increased specific populations with the potential to emulsify, lower interfacial tension, and lower oil viscosity, including the genera Arcobacter, Halomonas, and Thalassolituus. At the same time, some microbial species that are harmful for the oil recovery process (e.g., the sulphate-reducing bacteria Desulfovibrus, Desulfocurvus, Desulfocarbo, and Desulfoglaeba), were inhibited. In conclusion, nutrient flooding reduced the abundance of harmful microorganisms and increased beneficial functional microbial populations linked to beneficial functions, contributing to the enhancement of oil recovery in low-permeability oil reservoirs.

Green and rapid fabrication of superhydrophilic and underwater superoleophobic coatings for super anti-crude oil fouling and crude oil-water separation

The development of surfaces with super anti-crude oil-fouling behavior and crude oil-water separation properties is still a global challenge owing to the high viscosity of crude oil. Herein, superhydrophilic and underwater superoleophobic surfaces were successfully prepared by a simple, green and environmentally friendly one-step dip coating method. In the whole process, microcrystalline cellulose with hydrophilic hydroxyl functional groups was introduced into the coating with the help of inorganic adhesives, water was the only solvent, and no other organic solvents or surface modifiers was added. Besides being highly resistant to low viscosity oils and achieving effective oil-water separation (more than 98.3% separation efficiency after 30 cycles), the surface effectively resisted crude oil adhesion and achieved high viscosity crude oil-water separation. In addition, the underwater oil contact angle can still reach 147.5° and 152.5° after 20 cycles of sandpaper friction tests and 50 cycles of finger pressure tests, respectively, which indicates excellent durability. Furthermore, the method can achieve excellent superhydrophilicity and underwater superoleophobicity on varieties of substrates (such as copper foil, aluminum sheet and glass), showing very extensive applicability. It is expected that such fabrication strategy can provide a low cost, green and environmentally friendly approach to construct a series of superhydrophilic and underwater superoleophobic surfaces to achieve super anti-crude oil-fouling and (crude) oil-water separation.

Elucidation of the mechanistic aspects of chemical EOR in viscous oil systems

Chemical enhanced oil recovery techniques have been suggested as efficient alternatives to thermal methods in many thin/small viscous oil reservoirs in western Canada. These acidic oil reservoirs have been screened as good candidates for alkaline (A) and surfactant (S) floods. In this study, sand-pack core flooding experiments and pore-scale microfluidic tests were designed to give some new insights on the mechanisms of AS floods augmented with polymer (P) solutions in viscous oil systems.Viscous oil samples from Luseland field (14,850 mPa s at 25 °C) was used in all the experiments. The most efficient chemical generates ultralow interfacial tension, 0.002 mN/m, producing low viscosity type II (+) emulsion (740 mPa s, which is much lower than the viscosity of originating oil). The two pore volumes injection of this cocktail results in around 20% OOIP incremental oil recovery, which is almost doubled after injecting two pore volumes of extended water. The core effluents were all low viscosity oil in water emulsions, consistent with observations in batch mixing experiments. The incremental oil recovery to ASP flood is almost twice the recovery obtained in the polymer flood with nearly 4.5 times larger pressure build-up across the core. These observations suggest that the main mechanism is emulsification and oil entrainment rather than improvement in sweep efficiency.These speculated mechanisms based on the core scale observations were verified through the results of the microfluidic experiments. ASP solution can efficiently penetrate the residual ganglia or the edge of the water channels from which oil can be efficiently stripped. This oil is easily entrained in the form of low viscosity oil in water emulsions. Our results emphasize the critical role of polymer in the cocktail. In the absence of polymer, AS cannot efficiently penetrate the residual viscous oil leading to only a minuscule improvement in oil recovery.

Modeling Emulsification Influence on Oil Properties and Fate to Inform Effective Spill Response

Water-in-oil emulsification affects spilled oil fate and exposure, as well as the effectiveness of oil spill response options,viachanges in oil viscosity. While oil weathering processes such as evaporation, dissolution, photo-oxidation, and biodegradation increase oil viscosity about 10-fold, incorporation of water droplets into floating oil can increase viscosity by another order of magnitude. The objective of this study was to evaluate how changes in viscosity by oil type, with weathering, and with emulsification affect oil fate. Oil spill modeling analyses demonstrated that the increase in viscosity from emulsification prolonged floating oil exposure by preventing the oil from dispersing into the water column. Persistent emulsified oils are more likely to come ashore than low viscosity oils that readily disperse. Through a rapid increase in viscosity, emulsification restricted entrainment and slowed evaporation. Water column exposure to dissolved concentrations increased with lower viscosity oils. Thus, the ability to emulsify, and at what weathered state, are important predictors of oil fate. Oil viscosity is an important consideration for choosing response alternatives as it controls effectiveness of mechanical removal,in-situ-burning and surface-active chemicals. Therefore, understanding and quantification of oil emulsification are research priorities. The most influential model input determining emulsification and the emulsion’s viscosity is its maximum water content, as it controls the ultimate viscosity of the emulsion. Viscosities were also influenced by the volatile content and initial viscosity of the oil. Algorithms quantifying emulsion stability under field conditions have not been developed, so emulsions were assumed stable over the 30-day simulations. Changes in emulsion stability over time would affect oil properties and so floating oil and shoreline exposures, as well as response effectiveness. However, water column exposures to dissolved concentrations are determined within a few days of oil release, and as such would not be affected by differences in long-term stabilities of the emulsions.

Natural Frequency Analysis of Horizontal Piping System Conveying Low Viscosity Oil–Gas–Water Slug Flow

The water cut (WC) has a significant effect on the flow parameters, such as liquid holdup, liquid phase velocity, and flow regimes of the low-viscosity oil–gas–water slug flow, and it can change the vibration characteristics of piping systems. To study the effect of water cut on the vibration characteristics of piping systems conveying such internal flow, a new dynamic model is developed. Galerkin’s method is used to discretize the equation and determine the natural frequencies by solving for the eigenvalues of the equation coefficient matrix. The results show that in the range of 10–90% WC, the natural frequency increases and then decreases, and the turning point occurs near the phase inversion region (WC = 40–60%). The main reason is the highly effective viscosity in the phase inversion region, which leads to an increase in the liquid holdup. The natural frequency increases and then decreases with superficial gas velocity, and the inflection point decreases with the increase in water cut in the oil-based flow regime and increases with the increase in water cut in the water-based flow regime. The critical gas velocity is lowest near the phase inversion region, but it should be noted that the presence of the critical gas velocity is related to the pipe length and superficial liquid velocity. The results of the study provide a reference for the design of safe pipeline operation.

Characteristic Forced and Spontaneous Imbibition Behavior in Strongly Water-Wet Sandstones Based on Experiments and Simulation

Forced and spontaneous imbibition of water is performed to displace oil from strongly water-wet Gray Berea (~130 mD) and Bentheimer (~1900 mD) sandstone core plugs. Two nonpolar oils (n-heptane and Marcol-82) were used as a non-wetting phase, with viscosities between 0.4 and 32 cP and brine (1 M NaCl) for the wetting phase with viscosity 1.1 cP. Recovery was measured for both imbibition modes, and pressure drop was measured during forced imbibition. Five forced imbibition tests were performed using low or high injection rates, using low or high oil viscosity. Seventeen spontaneous imbibition experiments were performed at four different oil viscosities. By varying the oil viscosity, the injection rate and imbibition modes, capillary and advective forces were allowed to dominate, giving trends that could be captured with modeling. Full numerical simulations matched the experimental observations consistently. The findings of this study provide better understanding of pressure and recovery behavior in strongly water-wet systems. A strong positive capillary pressure and a favorable mobility ratio resulting from low water relative permeability were main features explaining the observations. Complete oil recovery was achieved at water breakthrough during forced imbibition for low and high oil viscosity and the recovery curves were identical when plotted against the injected volume. Analytical solutions for forced imbibition indicate that the pressure drop changes linearly with time when capillary pressure is negligible. Positive capillary forces assist water imbibition, reducing the pressure drop needed to inject water, but yielding a jump in pressure drop when the front reaches the outlet. At a high injection rate, capillary forces are repressed and the linear trend between the end points was clearer than at a low rate for the experimental data. Increasing the oil viscosity by a factor of 80 only increased the spontaneous imbibition time scale by five, consistent with low water mobility constraining the imbibition rate. The time scale was predicted to be more sensitive to changes in water viscosity. At a higher oil-to-water mobility ratio, a higher part of the total recovery follows the square root of time. Our findings indicate that piston-like displacement of oil by water is a reasonable approximation for forced and spontaneous imbibition, unless the oil has a much higher viscosity than the water.

Heat transfer characteristics of R‐454B and R‐454B/POE‐oil mixture on smooth and GEWA tube: Alternative to R‐410A

To clarify the compatibility of low GWP refrigerant R-454B alternative to high GWP refrigerant R-410A, the pool boiling heat transfer characteristics is presented subject to lubricant oil POEA-68. The tests were conducted on a smooth and highly structured GEWA-B5H tube at different saturated temperatures of 10, 0, and, −6 °C in 10 to 90 kW/m2 heat flux range. Results show that on both tubes the average heat transfer coefficient (HTC) of pure R-454B at all the saturation temperatures and heat flux is 26 to 34% lower than the pure R-410A. The heat transfer capacity of the GEWA-B5H tube is 2.5 to 5.5 times higher than compared to the smooth copper tube at the same saturation temperature and heat flux for both refrigerant R-454B and R-410A. Yet to elucidate the compatibility of POE oil with R-454B, the low viscosity oil POEA-68 is added by a mass fraction (ω%) of 1% to 10% and 0.25% to 5% for the smooth and GEWA-B5H tube, respectively. The mixing of oil alters the HTC, augmentation or deterioration in HTC compared to pure refrigerant is dependent on the liquid pressure (evaporator pressure), heat flux, boiling surface, and mass fraction of oil.

Thermal Friction Characteristics of Engine Elements - Boundary Lubrication of Cam and Tappet

As low-viscosity oil is used more widely to reduce friction losses in IC engines, concerns are growing about an increase in friction, wear and scuffing at the sliding surfaces on tribo-components. The authors conducted an analytical study on thermal friction characteristics of boundary lubrication based on the physical and chemical properties of interface materials and lubricants. The study was intended to investigate the effect of temperature on the function of oil additives as a friction modifier and/or anti-scuffing agent. Three low viscosity base oils, three extreme pressure and anti-wear agents and two organo-molybdenum friction modifiers were used to measure friction changes with a cam/follower test apparatus. The authors analyzed a relationship between friction and temperature in the running-in process of interfaces in consideration of the functional sensitivity of additives in low-viscosity oils. This analysis was focused on physicochemical properties on the basis that the oil viscosity, the adsorption of oil molecules, the chemical reaction of oil additives that forms a tribo-film low in shear stress, and the strength of interface materials are all under the influence of the exponential function of temperature, just like the Arrhenius’ equation. The results of the analysis found that the frictional shear stress changes depending on the intensity of involvement of surface temperature that affects oil viscosity, molecular adsorption / desorption and tribo-film formation in each running-in term.

Simulation and experimental research on the influence of lubrication on the comprehensive friction of TGDI engine

PurposeThis paper aims to investigate the effects of low-viscosity and ultralow-viscosity engine oils on the comprehensive friction and fuel economy of turbocharged gasoline direct injection (TGDI) through simulation analysis and experiments.Design/methodology/approachNumerical analysis models of friction loss for reciprocating, crankshaft and valve train are established. Based on the FAST, the friction loss of 24 specific parts of a TGDI engine was analyzed. Finally, the engine test bench was built, which was used to test the mechanical loss, external characteristics and universal characteristics.FindingsCompared with the baseline oil, lower viscosity lubricating oil can reduce the friction loss of nine components to varying degrees. When the viscosity decreases, the friction distribution ratio of reciprocating, crankshaft and balance shaft will gradually decrease. The proportion of reciprocating when using 0W12 is reduced by 4%. Tests have shown that ultralow viscosity engine oil reduces torque loss by up to 15.74% (2,000 rpm, full throttle), but its fuel consumption rate becomes higher in low-speed and high-torque conditions.Originality/valueThis work helps to understand the effect of lubricating oil characteristics on the comprehensive friction performance of the engine.

Development of Tribological Model of Human Fascia: The Influence of Material Hardness and Motion Speed

Low back pain is one of the most prevalent health disabilities worldwide. It is suggested that thoracolumbar fascia is possible causality of low back pain due to nerve innervation and pathological changes. A tribological model of fascia layers sliding across each other was developed in the present study. The influence of motion speed was investigated. The experiments were carried out in a pin-on-plate configuration using a normal load of 1 N and a range of speed from 1 to 5 Hz. Additionally, since fascia changes its structure depending on health conditions and physical activity, the influence of material hardness was studied. Therefore, different hardness of PDMS is considered to mimic different densities of the tissues. High-viscosity hyaluronic acid and low-viscosity oil were used as the lubricants. It was revealed that there is an apparent influence of lubricant viscosity with increasing material hardness. The friction increased with increasing movement speed for most of the PDMS hardness investigated. It seems the combination of high viscosity of hyaluronic acid, compliant material, and low speed can lead to low friction behaviour. Therefore, future studies will focus on finding even more compliant material for further development of the model towards mimicking the contact of human soft tissues.

Design of stable liquid infused surfaces: Influence of oil viscosity on stability

Slippery liquid-infused porous surfaces (SLIPS) have been used as a good alternative for superhydrophobic coatings due to their increased durability against mechanical forces and their ability to repel liquids with a wide range of surface tensions. SLIPS generally consists of a superhydrophobic porous structure infiltrated with a lubricant. The self-healing ability of SLIPS helps to maintain their water repellency longer than superhydrophobic surfaces. Even though SLIPS have great functionalities for practical applications, their stability is still insufficient due to the loss of lubricant from them. The oil loss from SLIPS depends mainly on the viscosity of the lubricant infiltrated into it. Even though plenty of research has been conducted over SLIPS with viscosities ranging from 1 cSt to 20, 000 cSt, a complete understanding of the oil loss mechanism is still not available. Therefore, in this work, we investigated the influence of silicone oil (lubricant) viscosity on the stability of SLIPS to determine a suitable viscosity range to fabricate stable SLIPS. Various SLIPS were fabricated by infiltrating silicone oils with a wide viscosity range. Stability studies were conducted by obtaining the volume of oil removed from the SLIPS with respect to the number of drops. Narrow SLIPS were also fabricated to understand the effect of self-healing speed on the oil loss process. Finally, a dynamic wicking experiment is conducted to determine the self-healing speed of silicone oils. SLIPS with silicone oil viscosities of 3000 cSt and 5000 cSt demonstrated lower loss rates and higher stability. However, the oil loss was fastest for SLIPS with 100 cSt silicone oil. Rapid self-healing of the lower viscosity oil was the main reason for the quick oil loss from lower viscosity SLIPS.

Numerical Assessment of Tribological Performance of Different Low Viscosity Engine Oils in a 4-Stroke CI Light-Duty ICE

<div class="section abstract"><div class="htmlview paragraph">Decreasing fuel consumption in Internal Combustion Engines (ICE) is a key target for engine developers in order to achieve the CO<sub>2</sub> emissions limits during a standard cycle. In this context, reduction of engine friction could help meet those targets. The use of Low Viscosity Engine Oils (LVEOs), which is currently one of the avenues to achieve such reductions, was studied in this manuscript through a validated numerical simulation model that predicts the friction of the engine’s piston-cylinder unit, journal bearings and camshaft. These frictional power losses were obtained for four different lubricant formulations which differ in their viscosity grades and design. Results showed a maximum friction variation of up to 6% depending on the engine operating condition, where the major reductions came from hydrodynamic-dominated components such as journal bearings, despite an increase in friction in boundary-dominated components such as the piston-ring assembly. Also, an evaluation of the potential fuel reduction that can be obtained by low viscosity oils during a WLTC approval cycle was performed. Overall, a fuel saving of 1% was obtained. In general terms, the majority of the engine map showed potential for mechanical loss reduction through LVEOs, that is, a better engine efficiency and consequently a decrease in the fuel consumption and CO<sub>2</sub> emitted to the atmosphere. The present work also exemplifies the trade-offs encountered when reducing the engine friction through LVEOs and highlights the need to co-engineer the hardware and lubricant in order to utilize the full friction reduction potential of LVEOs.</div></div>

Research on Ultra-High Viscosity Index Engine Oil: Part 1 - “Flat Viscosity” Concept and Contribution to Carbon Neutrality

<div class="section abstract"><div class="htmlview paragraph">In recent years, the realization of carbon neutrality has become an activity to be tackled worldwide, and automobile manufacturers are promoting electrification of power train by HEV, PHEV, BEV and FCEV. Although interest in BEV is currently growing, vehicles equipped with internal combustion engines (ICE) including HEV and PHEV will continue to be used in areas where conversion to BEV is not easy due to lack of sufficient infrastructures. For such vehicles, low-viscosity engine oil will be one of the most important means to contribute to further reduction of CO<sub>2</sub> emissions. Since HEV requires less work from the engine, the engine oil temperature is lower than that of conventional engine vehicles. Therefore, the reduction of viscous resistance in the mid-to-low temperature range below 80°C is expected to contribute more to fuel economy. On the other hand, the viscosity must be kept above a certain level to ensure the performance of hydraulic devices in the high oil temperature range. In order to achieve both of these characteristics, an oil whose viscosity has smaller temperature dependency (flat viscosity oil) is required. The flat viscosity oil can be achieved by using a low-evaporative, low-viscosity base oil and an ultra-high viscosity index Viscosity Modifier. It proved the possibility to achieve fuel economy equal to or better than 0W-8 while maintaining 0W-16 equivalent high temperature viscosity. This technology is applicable for vehicles calibrated with either 0W-16 or 0W-8 without negative impact on fuel economy performance. The flat viscosity 0W-16 will improve the fuel economy of in-use vehicles calibrated with conventional 0W-16 oils in the market significantly. As a result, CO<sub>2</sub> reduction can be achieved not only for new vehicles but also for vehicles in operation in the market that can contribute greatly to the carbon neutrality. In order for the flat viscosity oil to be widely used in the world, it is necessary to establish new engine oil specification.</div></div>

Prediction and Experimental Verification for Oil Transport Volume around Three-Piece Type Oil Control Ring Affecting Lubricating Oil Consumption

<div class="section abstract"><div class="htmlview paragraph">Reducing of lubricant oil consumption (LOC) remains a major issue for internal-combustion engines. Especially in recent years, in order to comply with Particular Number (PN) regulations and lower oil viscosity to reduce friction loss, need to reduce the LOC has increased. Controlling the upward oil flow, that passes the piston and piston rings, is effective in reducing the LOC. In addition, oil control ring (OCR) has significant effect on upward oil flow. Therefore, development of a high-precision prediction method of oil behavior around the OCR is important for prediction of LOC. So, the model of Three-piece type oil control ring (3POCR) motion within the OCR groove and the model of oil behavior around the 3POCR were developed using the computer aided engineering (CAE) method in this paper. These models calculate in detail the upward oil outflow to the 3rd land from the OCR groove, which is based on the relation between the OCR motion and the gas pressure as well as the inertial force of oil. Since factors that greatly affect the prediction accuracy are the gas pressure around the OCR and the OCR motion, these were measured and verified in the actual engine. Furthermore, oil behavior observation using in-cylinder visualization engine, and oil film thickness measurement using optical fiber were conducted for experimental verification of the oil behavior model around the 3POCR. As a result, qualitative tendency of calculated results and measured results showed good agreement. Also, comparison in two different OCR specification, the similarly tendency was obtained. Therefore, the effectiveness of the developed prediction model was confirmed.</div></div>

Numerical study of hydrodynamic herringbone-grooved journal bearings combined with thrust bearings considering thermal effects

Abstract Hydrodynamic herringbone-grooved journal bearings (HGJBs) are analyzed by solving Navier–Stokes and energy equations. It is well known that the load capacity of hydrodynamic bearings may be affected by high temperatures and low oil viscosity. Therefore, the main objective of this study is to understand the pressure distribution of hydrodynamic HGJBs under different oil viscosity and eccentricity ratios. In this paper, 3 different configurations are studied, namely, a HGJB, a combined HGJB and thrust bearing, and a combined HGJB and grooved thrust bearing. The bearing characteristics, such as load capacity and attitude angle that vary with different eccentricity ratios, are also discussed. The results show that the load capacity of the bearing decreases with increasing temperature. The pressure difference also increases as the eccentricity ratio increases. The high-pressure region is concentrated at the tip of the groove for the HGJB. In addition, the combined HGJB and grooved thrust bearing can be used to stabilize the journal because of the low attitude angle. These findings may help and facilitate the design of hydrodynamic bearings suitable for working in warm and hot environments in the future.