Lubricating Oil Research Articles

Can lubricant oil promote undesired self-ignition of the charge in hydrogen engines?

Hydrogen utilization in internal combustion engines is deemed a viable solution for promoting a rapid transition towards a carbon-free mobility, especially for those hard-to-electrify applications. However, critical aspects still poorly understood remain and need to be investigated in order to accelerate the development of such a promising technology. Some of these might originate from the undesired but unavoidable participation of lubricant oil to the combustion process. The present work aims at ascertaining if the lubricant oil chemical characteristics can be at the basis of the onset of certain uncontrolled self-ignition modes of the charge. Considering a lubricant oil droplet suspended in a H2/air environment, an analytical model was developed to derive essential information about mixture composition and thermodynamic conditions that might establish where oil contamination occurs. The results were used to initialize zero-dimensional numerical simulations performed in the OpenSMOKE++ framework with the aim of highlighting charge reactivity variations induced by the presence of oil vapour in the vicinity of an oil droplet. A reduced chemical model, developed for this very purpose in a previous recent work, was employed in the simulations for emulating the reactivity properties of the H2/oil/air mixture.

Test bench development and implementation for experimental determination of mechanical losses in single cylinder internal combustion engines

As mechanical efficiency has great relevance in the alternative engine performance, the authors research in the development of testing facilities to characterize the sources of engine mechanical losses. The present paper deals with the realization of a hardware platform to conduct experimental studies in small combustion engines to experimentally characterize the mechanical losses of a single-cylinder internal combustion engine by means of the indicated diagram and motoring methods. The system was completed by means of an electrical motor-generator coupled to a single-cylinder air-cooled spark ignition engine, a self-developed electronic hardware control, and a PC-based instrumentation and data acquisition system. Specifications of load-motoring-starting system, including the description of the proprietary electronic load regulation system, are detailed. Also, the instrumentation system of in-cylinder and intake pressures; Temperatures of intake air, exhaust gases, lubricant oil, and engine block; effective torque and crankshaft position are described, including the signal acquisition system. The methodologies for indicated diagram and motoring method are described, mentioning the required measurements to apply each method and the engine load-temperature considerations when an engine is tested in fired or motored conditions. The platform was used to study the mechanical losses of the engine under motored and fired conditions under a wide range of rotational speeds and throttle openings, allowing to draw conclusions about the operating features of the developed test bench in itself, and also about the mechanical losses of the engine tested. Initially, samples of cylinder pressure, torque, intake pressure as function of crank angle and indicate diagram were obtained, showing similar waveforms present in related literature. Then, variations of the aforementioned temperatures against rotation speed and throttle opening and results for the mechanical losses determined by indicated diagram and motoring methods are shown. Finally, two empirical correlations are proposed to estimate the mechanical losses. In the future the hardware platform will be utilized to investigate in-cylinder engine parameters, detailed thermal and mechanical engine performance

Влияние регенерации слоистого модификатора трения на триботехнические свойства смазочных композиций

The paper examines an influence of the regeneration efficiency of the developed anti-wear additive on tribological properties of the lubricating composition, including a lubricating oil and the additive. The anti-wear additive was a layered friction modifier – molybdenum diselenide MoSe2, mixed in the volume of a composition of unsaturated fatty acids – stearic acid and oleic acid. Lubricating oil M-16G2TSS was chosen as the base lubricant, with respect to which the tribological properties of other lubricants submitted for testing are compared. For all cycles of tests, a volume of no more than 25 cm3 of lubricant was used to avoid high thermal inertia when the test samples moved on the friction machine. Experiments of the regeneration of the additive were carried out on a rotary mixing unit of the author's design, and the solution has a long storage period of 8 640 hours (about 12 calendar months). The possibility of restoring the uniform distribution of molybdenum diselenide throughout the volume of the additive in a suspended state has been revealed. This lubricant composition, after restoration of the structure by stirring, can be used in the production of a lubricant composition based on M-16G2TSS oil. Using a reciprocating friction unit of a friction machine, simulating the cylinder-piston group of a marine diesel engine, the resulting lubricant composition was compared with other lubricants based on molybdenum diselenide, the additive solutions of which have different storage periods before being added to the lubricating oil, as well as with the base lubricating oil. The assessment of the tribological properties of lubricants based on M-16G2TSS oil by determining the weight wear and further using this value to estimate the resource of the friction unit has been made. Rotational regeneration has shown satisfactory effectiveness in partially restoring of the tribological properties of a lubricant composition with the participation of an additive, but is not enough effective compared to rotational pulsation mixing of the additive in order to create perspective lubricant compositions.

Operational stability influenced by lubricant oil charge in the CO2 automotive air conditioning system

In a vapor compression refrigeration system, the oil enhances the efficiency of the compressor but impairs the performance of the heat exchanger. This paper focuses on the experimental study of the influence of oil quantity on the operational stability of CO2 air conditioning system. The operational stability of the system under different oil charge quantity and operating conditions is studied. The experimental results indicate that when the oil circulation rate increases to a certain value, the adjustment of electronic expansion valve (EXV) opening or the compressor speed will cause system fluctuation and the outlet of evaporator gets close to no superheat. The critical oil circulation rate of the experimental system is about 9.2 %. The analysis of the fluctuation shows that it becomes more severe with the increasing of the refrigerant mass flow rate. When the mass flow rate increases from 210 kg∙h − 1 to 250 kg∙h − 1 at 7000 r min−1 of compressor speed, the fluctuation frequency increases from 0.072 Hz to 0.095 Hz. The occurrence of unstable phenomena has remarkable impact on system performance, the maximum difference of this system in instantaneous cooling capacity and COP during the fluctuation period is respectively 0.5 kW and 0.13.

A greener sample preparation procedure using reverse-phase dispersive liquid–liquid microextraction for multielement determination of inorganic species in petroleum-derived samples

This study describe the development and first application of reverse-phase dispersive liquid–liquid microextraction (RP-DLLME) sample preparation for the determination of Ca, Cd, Cu, Fe, K, Mg, Mn, Ni, Pb, and Zn in petroleum-derived samples using inductively coupled plasma optical emission spectroscopy (ICP OES). Some factors inherent to RP-DLLME were optimized using multivariate statistical analysis through the 24 full factorial design followed by the Doehlert matrix. The established RP-DLLME procedure employs 5.0 g of samples, 1600 µL of the 3.75% (v/v) HNO3:isopropyl alcohol [3:1 (v/v)] extractive solution, 10 min of thermostatic bath at 80 °C, 60 s of vortexing, 3 min of sonication at 55 °C, and 15 min of centrifugation at 3500 rpm. The resulting aqueous phase volume was adjusted up to 15 mL with ultrapure water, and ICP OES carried out the measurements. Relative standard deviations (RSD) less than 3.5%, linear correlation coefficients better than 0.9985, and limit of detection (LOD) in the range of 0.57 ng g−1 (Mn) to 107.6 ng g−1 (K) were obtained for the determination of the analytes. Accuracy of the RP-DLLME using ICP OES was evaluated by analysis of the V21 + K metallo-organic standard, and recovery percentages within the 89.4–98.3% interval with RSD less than 6.4% were obtained. The accuracy and precision were also evaluated through a recovery test, and the results were in the range of 87.1–95.7% with RSD less than 4.9% for all analytes. Therefore, the RP-DLLME-ICP OES methodology was successfully applied to gasoline, diesel oil, JET-A1 (jet fuel), Avgas (aviation gasoline), lubricant oil, and vaseline samples, and the contents were obtained for almost all analytes. Although there are no regulatory resolutions for all petroleum-derived samples, the content of the analytes determined in JET-A1 and Avgas samples complied with ANP Resolution No. 856/2021 and 901/2022 legislation, respectively. Furthermore, the relative simplicity of the RP-DLLME combined with the accurate and precise measurements carried out by ICP OES can be a viable alternative in routine analysis.

SIMULATION OF OPTIMAL MIX OF SIO2-TIO2-AL2O3 NANO ADDITIVES FOR THE MINIMAL WEAR AND COEFFICIENT OF FRICTION OF LUBRICANT USING FUZZY LOGIC

Nano-particles of oxides of various metals are typically added with the base lubricants for enhancing the tribological properties, especially the wear and coefficient of friction of the lubricants. However, it is required to determine the optimum proportion of mix of the nano-additives in order to obtain the desirable characteristics gained through the addition of various oxides of metals mixed with the lubricants. This paper deals with the application of fuzzy logic to simulate the various proportions of a mix of three nano-additives of SiO2, Al2O3 and TiO2 with the corresponding predicted values of tribological characteristics of wear and coefficient of friction. The limited number of outcomes obtained from a full factorial design of experiments carried out with these three nano-additives at three different levels of mixing, are used as inputs to the fuzzy logic simulation. This approach facilitates simulating as many combinations of nano-additives as possible with the base lubricant oil along with the predicted output of characteristics of interest, which otherwise will be cumbersome to carry out the experiments for all the combinations of mix of additives.

Physicochemical properties of soot in diesel engine lubricating oil: characterizations and impact on frictional characteristics

The study investigates the effects of the physicochemical properties of engine sump soot on the frictional characteristics of its contaminated engine oils. Moreover, the relationship between soot physicochemical properties and its frictional characteristics was also discussed. The results showed that the properties of the two kinds of lubricating oil (A, B) used in diesel engines affect the properties of engine sump soot (Soot-A, Soot-B), i.e. Soot-A showing smaller aggregate size, larger primary particle diameter, more disordered nanostructure, and higher functional content than those of Soot-B. For both soot particles, as the amount of soot particles added to the formula oil went up from 1 wt.% to 2 wt.%, the wear scar diameter (WSD) and friction coefficient of the wear spot increased. For both soot particles, the main wear form of the steel ball wear area was abrasive wear (more than 90%), accompanied by a small amount of plastic deformation and pitting (less than 2%). With the same amount of soot in lubricating oil, soot with a higher degree of graphitization, low oxygen content and low reactivity may cause smaller WSD and lighter wear. Moreover, a larger soot accumulation would result in deeper plow marks and pits in the abrasion areas.

Characteristics of ash formed by different lubricant additives and its effect on DPF performance

Diesel Particulate Filter (DPF) is an important technology to reduce diesel exhaust particles. The ash formed by the combustion of lubricant oil will be deposited in the DPF, which will affect the filtration efficiency of DPF. In this paper, the ash generated in the burner by combustion of two lubricant additives mixed with diesel fuel were obtained by the burner test of ash rapid loading. The microscopic morphology of ash was studied by scanning electron microscopy and the fractal dimension was calculated based on fractal theory. Chemical composition analysis was performed using energy-dispersive X-ray spectroscopy. The filtration efficiency of DPF was tested with EEPS 3090 when loaded with different ash fractions. The results show that the average fractal dimension of Mg-based ash (1.5791) is higher than that of Ca ash (1.5420), indicating a more detailed surface structure at the microscopic level. This suggests that Mg-based ash is more likely to plug, sinter and even form bridging phenomenon in the DPF inlet channel. The filtration efficiency of DPF increases and then decreases with the loading of ash. The capture efficiency of large particles of 40–200 nm is increasing with the loading of Ca-based ash. However, due to the higher fractal dimension, the loading of Mg-based ash can significantly improve the capture efficiency of small particles of about 10 nm. This work is beneficial to explain the influence of ash on the efficiency of DPF in filtering particles of different sizes.

The effect of oil raw material composition in the synthesis of bio‐sorbents based on inverse vulcanization on the ability to remediate hydrocarbon‐contaminated water. A novel method for decontaminating water/fuel emulsions

AbstractSolid crosslinked biopolymers made by inverse vulcanization of soybean (PSB) or sunflower (PSF) oil with sulfur are characterized and tested to decontaminate water from hydrocarbons (HC): gasoline, diesel, two lubricant oils, and water/gasoline emulsion. The physicochemical structure of the biopolymers is studied by FTIR spectroscopy, Differential scanning calorimetry, contact angle measurement, and mechanical testing. Also, the morphological structure is analyzed by scanning electron microscopy. Moreover, the polymer decontamination capability and reusability are tested gravimetrically. Both biopolymers are formed by CS bonds, and their elastic behavior dominates. However, PSF is more hydrophilic, has a larger amount of free sulfur and a less compact structure, and also sorbs ca. 60% more HC than PSB. The results indicate that the unsaturated feedstock has a strong effect on the polymer structure and the capacity to remediate contaminated water or solids. Also, both materials can be reused to remediate water for more than five consecutive cycles. In addition, inverse vulcanization of oils and sulfur is an ecological way of obtaining environmentally‐improved materials with great potential and applications, providing a complete atomic economy and high performance to remediate water from water/HCs dispersed and, more importantly, from water/gasoline emulsions.

A novel constant pressure control method for nucleation boiling of CO2/lubricant in molecular dynamics simulation

Conventional molecular dynamics simulations of nucleation boiling typically employ the fixed volume method, resulting in a non-constant pressure during the boiling process. In this paper, we propose an additional pressure control method, placing a cover plate at the top of the liquid phase to achieve liquid phase pressure control during boiling. The novel method yields a pressure control error within ±5 %. CO2 and CO2/PEC4 lubricating oil mixture are used to investigate the differences in heat transfer characteristics between non-constant and constant pressure nucleation boiling. Furthermore, the effect of PEC4 lubricating oil on CO2 nucleation boiling under a fixed pressure condition is explored. The results show that both the bubble nucleation and growth time of CO2 and the CO2/PEC4 mixture are prolonged under constant pressure. This causes a compression in CO2 molecular spacing, thereby reducing CO2 diffusion and mass transfer capabilities. Heat transfer from the solid to the liquid, and within the liquid itself, is diminished, while the distribution of PEC4 molecules within the liquid phase becomes more even. The migration rate of PEC4 molecules in the liquid phase slows down. Under the constant pressure model, PEC4 increases the mass transfer resistance of CO2. As the lubricant mass fraction rises, The nucleation and growth rate of CO2 bubbles decline. In comparison to CO2, PEC4 molecules exhibit a stronger interaction energy with the Cu wall surface. During boiling, some PEC4 molecules accumulate on the Cu surface, forming an oil film that impedes the direct contact between CO2 molecules and the Cu wall.

Comprehensive analysis of reclamation of spent lubricating oil using green solvent: RSM and ANN approach

Comprehensive analysis of reclamation of spent lubricating oil using green solvent: RSM and ANN approach

Ignition of Various Lubricating Oil Compositions Using a Shock Tube

Abstract With new restrictions imposed on gas turbine efficiencies and power outputs, lubricating oils are used at higher temperatures and harsher conditions leading to potential, unintended combustion. To establish an understanding of lubricating oil's resistance to combustion, a new spray injector system was utilized in the High-Pressure Shock Tube (HPST) Facility at the TEES Turbomachinery Laboratory at Texas A&M University. Two gas turbine oils (Mobil DTE 732 and Castrol Perfecto X32), a base mineral oil, and a surrogate (n-hexadecane) were tested at postreflected shock conditions at equivalence ratios near 2.5. Castrol Perfecto X32 was also characterized at an equivalence ratio near 1.2. All of the lubricating oils displayed ignition between temperatures of 1152 and 1383 K and near atmospheric pressures. To characterize combustion, two different definitions of ignition delay time (IDT) were considered: sidewall OH* chemiluminescence and sidewall pressure. Both definitions were used to create temperature-dependent correlations for each of the lubricating oils. In general, both definitions provided similar results within the accuracy of the measurements. One trend from the data herein is that the brand-name oils (Mobil DTE 732 and Castrol Perfecto X32) provided ignition delay times that were similar to each other but slightly larger than the corresponding mineral oil and n-hexadecane results. This difference could be attributed to the additives that are present in the brand-name oils.

Analysis of characteristics of electric field-enhanced multi-gradient of solid particles in oil

Lubricating oil is easily polluted by solid particles, causing it to deteriorate; therefore, solid particles must be separated from the oil. Furthermore, as conventional filtration devices cannot meet both filtration accuracy and service life requirements, an oil and solid separation method for multi-gradient filtration enhanced by an electric field is proposed. A numerical model for multi-gradient separation was established by coupling the governing equations of electric and flow fields, the particle-wall collision equation, and the discrete phase-tracking equation. Enhanced by an electric field, the characteristics of the multi-gradient filtration of solid particles in oil were investigated using finite element method. The effects of the main control parameters on the filtration performance were analyzed. The results indicate that using the electric field-enhanced multi-gradient filtration method can achieve highly efficient separation of solid particles from the oil. When the electric field strength was increased from 0 kV/mm to 2 kV/mm, the deposition concentration of particles was 2.5 times higher and filtration efficiency of the system increased to 97.46%. Additionally, the deposition concentration and filtration efficiency decreased from 0.15 m/s to 0.3 m/s, while gradually increased from 0.3 m/s to 0.5 m/s, for a particle size range of 10–40 µm.

Superior shear-stable slippery surface of porous carbon nanospheres (PCN)-oleogel

Frictional drag reduction (DR) is of great importance in marine environments as it has the potential to significantly reduce fuel consumption, leading to both economic and environmental benefits. While various conventional DR techniques exist, many of them are energy-inefficient and require external intervention to function effectively in real marine conditions. Unlike conventional methods, bioinspired surfaces offer cost-effective and sustainable DR. However, these surfaces suffer from (i) poor durability of superhydrophobic surfaces, (ii) limited scalability, (iii) substrate dependency of coatings, and (iv) fast depletion of impregnated lubricant oil of liquid infused surfaces (LIS). In this work, we proposed a double-layered LIS oleogel surface embedded with re-entrant surface (RES) morphology by adopting spin/spray-assisted deposition processes. The RES structure, achieved by depositing porous carbon nanospheres (PCN) on the oleogel surface, effectively stabilized and replenished a large amount of lubricated oil, ensuring long-lasting lubrication. The developed PCN-oleogel surface could retain its slippery property despite exposure to harsh physical abrasion, and various chemically contaminated aqueous solutions. The developed PCN-oleogel exhibited long-term lubrication performance and shear-stable durability under high-speed, high-pressure conditions up to 15 ms−1 — such shear-stable lubrication in extremely rare in literature. Conclusively, the proposed PCN-oleogel surface is envisioned to have a great potential in achieving sustainable underwater DR in harsh marine environments.

Study on the rate of change of thread angle and thread distance considering the interference factor under before and after the dynamic vibration of the fastening system

Precision nuts are widely used in tool spindles and ball screws. Proper locking gives the bearing the right amount of pre-pressure so that the inner balls can roll steadily and inhibit friction and rapid temperature rise. If no pre-pressure is given to the bearing, it will cause the inner ball to slide irregularly and generate extremely high temperatures. In this paper, the precision nuts used are the flank locking precision locked nut and clasp locking precision locked nut for Taguchi method experiments. The control factors are nut type, Fitting clearance, and lubrication oil. Interference factors are surroundings temperature, assembly personnel, and torque wrench. The purpose is to obtain more suitable anti-loosening characteristics by the Taguchi method under the influence of interference factors and to check the thread angle and thread pitch before and after the experiment. The experimental results were analyzed form Taguchi method to find the combination of parameters with the maximum S/N and the variance analysis to obtain the significant factor. Finally, the regression equation of the loosening prevention characteristics was obtained by regression analysis, which shows that the optimized parameters effectively improve the loosening prevention characteristics and explore the interference factor on the loosening prevention characteristics of precision nuts.

Analisis Kebutuhan Pelumasan saat Kegagalan Sistem Kelistrikan (Black Out) pada Kompresor Boil Off Gas (K-6801) pada Fasilitas LNG Hub

The lube oil system in the compressor plays an important role for any rotating equipment because it functions to provide lubrication against the effects of friction on various rotating equipment. This overhead tank works by gravity to distribute lubricating oil from operating speed to zero rpm. The large volume of lube oil provides lubrication to the compressor bearings when the normal circulating flow from the pump stops and is assisted by the backup flow from the overhead tank. The purpose of this approach is to calculate the need for lubrication when an electrical fault occurs in the Boil-off Gas compressor (K-6801). Based on the results of analysis and calculations where the Boil-Off Gas Compressor (K-6801) is the object of observation, the amount of lubricating oil needed for the remaining rounds is 1885 liters while the amount of lubricating oil available in the field is 1528,286 liters. From the calculation results, 1528,286 liters is sufficient based on the reference API Standard 614 edition 4, chapter 2, Section 1.4.10.2 because it has exceeded the 20% reduction from 1885 liters, namely 1508 liters. The height of the overhead tank that is suitable for flowing lubricating oil to the compressor bearings is 5.2588 meters above the compressor with a distribution pipe diameter of 3 inches and an orifice bore diameter of 1 inches.

Investigation of Lubricant Oil Film Thickness on Workpiece under Minimum Quantity Lubrication Milling Process

Investigation of Lubricant Oil Film Thickness on Workpiece under Minimum Quantity Lubrication Milling Process

Engine Oil Impurities and level Monitoring System

The key element for mechanics of every vehicle be it a 2-wheeler, 3-wheeler, 4-wheeler and so on requires engine oil to work smoothly. Engine oil's primary function is to lubricate the moving elements of engines, which are constantly undergoing friction. As a result, friction is decreased, which tends to diminish longevity of engine parts. During combustion, energy is wasted, and mechanical parts rubbing against one another raise engine temperature. With increased usage the engine takes a lot of wear and tear this leads to accumulation of impurities in the oil. The project describes the design and development of an IoT based oil impurities, level monitoring instrument and its operational methodology. This project uses a unique approach with LED spectrophotometry. The developed instrument in the project will do Qualitative and Quantitative assessment of lubricant oil in IC engine’s sump. This in turn aids in carrying out decisive actions to maintain the ecological emissions and engine life cycle.

Flow boiling heat transfer characteristics of zeotropic refrigerant/oil mixtures in horizontal smooth tube

In the Organic Rankine Cycle (ORC), the lubricant is inevitably mixed with the working fluid, which affects its flow boiling heat transfer characteristics in the evaporator. In this study, the flow boiling heat transfer characteristics of zeotropic fluid R141b/R245fa at different polyester oil (POE) concentrations were experimentally investigated. Meanwhile, the effects of heat flux, mass flux and vapor quality were also investigated. The results show that both the mass flux and vapor quality can increase heat transfer coefficient (HTC) and frictional pressure drop (FPD), while the heat flux decreases the HTC and increase the FPD. The maximum promotion of HTC is achieved at an oil concentration of 2.3% compared to other concentrations. Except for the oil concentration of 3%, the FPD of R141b/R245fa-POE mixture increases with the oil concentration. Additionally, the effects of lubricant oil on the HTC and FPD of refrigerant/POE mixture were discussed. The Schager-R22/150-SUS correlation can well predict the enhancement factor of HTC and penalty factor of FPD. The comprehensive factor is always greater than 1, so POE can enhance the overall heat transfer performance of refrigerant-POE mixture.

Experimental investigation of hydrogen combustion in a single cylinder PFI engine

The simultaneous reduction of Green-House Gases (GHG) and criteria pollutants is the main target of current Internal Combustion Engines (ICE) development. Hydrogen (H2) fueling is one of the best options available in both regards, as it does not emit tailpipe CO2 as well as significantly abates all criteria pollutants already at engine-out level. However, optimizing hydrogen combustion in order to exploit the fuel proprieties at best is a challenging task due to the very particular properties of the fuel. In fact, H2 combustion in ICE promotes a very clean, fast and complete combustion process, with extremely low HC, CO, and PM engine-out emissions stemming only from lubricant oil. The usage of lean-boosted and EGR-diluted combustion strategies can significantly contribute to raise the brake thermal efficiency and lower the NOx emission to extremely low levels. To this end, the Authors tested a 0.5 L single cylinder engine featuring an optimized PFI layout and dedicated piston bowl profile for a retrofitted Diesel operating as H2 monofuel, in SI mode. In this paper, the authors discuss the effect of the main engine parameters, extensively investigated by means of Design of Experiments (DoE) techniques, as well as the effect of dilution and EGR to promote clean and efficient hydrogen combustion, in order to recommend the most effective practices.