Increase In Oil Temperature Research Articles

Numerical and experimental studies on the thermal characteristics of the clutch hydraulic system with provision for oil flow

PurposeThis paper aims to investigate the thermal characteristics of the clutch hydraulic system under various oil flow conditions. Increasing the oil flow is one of the most important approaches to reduce the clutch temperature. However, the effect of the oil flow on the clutch temperature remains to be explored.Design/methodology/approachThe thermal resistance network model and the lumped parameter method are used to study the thermal characteristics of the clutch hydraulic system. The predicted temperature variations of the clutch and the oil are compared with experimental data.FindingsResults demonstrate that the larger the friction power is, the higher the temperatures of the clutch and the oil are. However, the temperature growth rates of the clutch and oil present different trends: the former decreases gradually and the latter increases constantly. Additionally, increasing the oil flow within a certain range gives rise to the decrease of clutch temperature and the increase of oil temperature; nevertheless, their variation trends are gradually weakening. When the oil flow is large enough, it brings a slight effect on the clutch temperature rise.Originality/valueThis paper extends the knowledge into the oil flow supply of the clutch hydraulic system. The conclusions can provide a theoretical guidance for the oil management of the transmission system. Additionally, the thermal resistance network model is also effective and efficient for other hydraulic equipment to predict the temperature variation.

Prediction the variation range of wax deposition with temperature of crude oil in a flow loop

Wax deposition under different temperature conditions was investigated in a flow loop, using a local crude oil with a wax content of 22.5%. The results revealed that the wax deposition increases with increasing coolant temperature. However, the amount of deposit increased initially with increasing oil temperature and then decreased. Based on these results, the corresponding temperature ranges were divided into three ranges: hot flow, sensitive precipitation of wax crystal, and cold flow. Based on diffusion mass, a method and steps for determining the temperature dependence of wax deposition were proposed.

A Technical Review on the Study of Stability Analysis of Non-Circular Bearings Lubricated with Newtonian/Non-Newtonian Fluids

In recent years, applications of non-Newtonian fluids as lubricants have received great interest since the use of these non-Newtonian lubricants showed an increase in load carrying capacity and reduction in frictional force with the escalation in additives concentration. The demands of the present day industry rotating machinery includes high speed, compactness, light weight engines, high operating loads, high power transmission, high efficiency, and high performance of the engine. As a result of high speed machines, bearings are inclined to have excessive power loss and increase in oil temperature. The former reduces the efficiency of the engine and the latter causes the undesired changes in the lubricating oil. The plain journal bearings at high rotation speeds are subjected to instability like oil whirl and whip ruining the bearing and also the machine. Therefore, this poses a need to change in the bearing design. In the present paper, an attempt is made to briefly introduce the various non-linear models used and the different approaches that have been carried out by the researches in the past few years to improve and achieve the stability of journal bearing along with enhanced performances and characteristics.

Color changes kinetics during deep fat frying of kohlrabi (Brassica oleracea var. gongylodes) slice

ABSTRACT Kohlrabi is used for consumption in various regions of the world as, raw, cooked or fried. Heat and mass transfer phenomena take place during frying cause physicochemical changes, which affect the color and surface of the fried products. The effect of frying temperature on the color changes and center temperature change during deep fat frying of kohlrabi was investigated. The color scale parameters redness (a*), yellowness (b*) and lightness (L*), and color change intensity (∆E) were used to estimate color changes during frying as a function of oil temperature and time. L* value of fried kohlrabi decreased during frying but a* and b* values were increased. A first-order kinetic equation was used for each one of the three color parameters, in which the rate constant is a function of oil temperatures. The results showed that oil temperature has a significant effect on the color parameters. Different kinetic models were used to fit the experimental data, and the results revealed that the power model was the most suitable to describe the color change intensity (∆E). Center temperature of kohlrabi slice increased with an increase in oil temperature and time during frying.

Study of Transformer Lifetime Due to Loading Process on 20 KV Distribution Line

Power transformer is very important in electric power system due to its function to raise or lower the voltage according to its designation. On the power side, the power transformer serves to raise voltage to be transmitted to the transmission line. On the transmission side, the power transformer serves to distribute the voltage between the main substations or down to the distribution voltage. On the distribution side, the stresses are channeled to large customers or lowered to serve small and medium customers. As the power transformer is so importance, it is necessary to protect against disturbance, as well as routine and periodic maintenance, so that the power transformer can operate in accordance with the planned time. Some factors that affect the duration of the power transformer is the ambient temperature, transformer oil temperature, and the pattern of load. Load that exceeds the maximum efficiency of the transformer which is 80% of its capacity will cause an increase in transformer oil temperature. Transformer oil, other than as a cooling medium also serves as an insulator. Increasing the temperature of transformer oil will affect its ability as an isolator that is to isolate the parts that are held in the transformer, such as iron core and the coils. If this is prolonged and not handled properly, it will lead to failure / breakdown of insulation resulting in short circuit between parts so that the power transformer will be damaged. PLN data indicates that the power transformer is still burdened exceeding maximum efficiency especially operating in the work area of PLN South Bali Area. The results of this study, on distribution transformers with different loads, in DS 137, DS 263 and DS 363, show that DS 363 transformer with loading above 80% has the shortest residual life time compared to DS 263 and DS 137 which loading less than 80%.

Color changes kinetics during deep fat frying of carrot slice

Heat and mass transfer phenomena take place during frying cause physicochemical changes, which affect the colour and surface of the fried products. The effect of frying temperature on the colour changes and heat transfer during deep fat frying of carrot has been investigated. The colour scale parameters redness (a*), yellowness (b*) and lightness (L*), and color change intensity (∆E) were used to estimate colour changes during frying as a function of oil temperature. L* value of fried carrot decreased during frying. The redness of fried carrot decreased during the early stages of frying, while it increased afterwards (become more red). A first-order kinetic equation was used for each one of the three colour parameters, in which the rate constant is a function of oil temperatures. The results showed that oil temperature has a significant effect on the colour parameters. Different kinetic models were used to fit the experimental data and the results revealed that the quadratic model was the most suitable to describe the color change intensity (∆E) (R > 0.96). Center temperature of carrot slice increased with increase in oil temperature and time during frying.

Thermo-hydrodynamic performance of tilted non-circular micropolar lubricated journal bearings

PurposeThe purpose of this study is to examine the thermo-hydrodynamic performance of tilted non-circular journal bearings lubricated with a micropolar fluid. The investigated bearing types are two- and three-lobe journal bearings with finite length.Design/methodology/approachFor this purpose, modified Reynolds, energy and three-dimensional Laplace equations are solved numerically by using generalized differential quadrature method. The effects of micropolarity characteristics of lubricants, such as characteristic length and coupling number, as well as tilt angle as a design parameter, on the performance of non-circular two- and three-lobe journal bearings are studied.FindingsThe results show that the tilt angle can affect the temperature and pressure profiles causing variation in the performance of non-circular bearings. Increasing coupling number and decreasing characteristic length cause the load-carrying capacity to decrease because of the increase in maximum oil temperature of the fluid film of lubricant and decrease in the minimum oil base viscosity. So, it is possible to select suitable values of tilt angle for achieving optimum performance of these bearings.Originality/valueThe non-circular bearings suggest several design parameters such as tilt angle for designers. By considering thermal effects for micropolar lubricant, the requirements of a specific application can be fulfilled.

Research of the Frictional Characteristics of Piston Ring - Cylinder Liner Based on GT-Suite

Establish the piston ring-cylinder liner frictional model using the software of GT-Suite combine both of the frictional condition and lubrication, analyze and compute the thickness of oil film between piston ring and cylinder liner, the distribution of oil stress, and the force and power of the friction in rated condition. Then, mainly analyze the thickness of oil film and power of friction at the first piston ring under different temperatures of lubrication oil and different speeds. The results indicate that: The lubrication effect at first piston ring is poor, and the consumption of frictional power is high. The frictional power is significantly reduced with the oil temperature increases. However, the thickness of the oil film will decrease with the oil temperature increases, which is bad to the lubricational condition. Considering both of the lubrication condition and the frictional power, the frictional characteristics are better when the oil temperature is maintained at 80-90°C. With the increase of rotational speed, the oil film thickness and frictional power increase, but comparing with the influence on the frictional power, the change of rotational speed has less influence on the oil film.

Variation of Discharge Characteristics With Temperature in Moving Transformer Oil Contaminated by Metallic Particles

During the operation of power transformers, the insulating oil is actually in a moving state due to the effects of various cooling systems. Therefore, the investigation on insulation characters of moving transformer oil is necessary. In this paper, the influences of temperature on partial discharge (PD) and breakdown characteristics of moving transformer oil contaminated by metallic particles were experimentally studied at first. It was found that the PD magnitude and frequency first decreased and then became higher when the temperature increased from 40 °C to 80 °C, and a minimum point appeared between 70 °C and 80 °C. On the contrary, the dependence of breakdown voltage on temperature showed an opposite tendency. In order to explain the experimental results, a simulation model involving multiple forces was constructed to obtain the movement trajectory of particles. The increase of oil temperature leaded to the decrease of dynamic viscosity of transformer oil, so the forces acting on particles and their movement characters changed. As the temperature increased, the collision frequency between particles and electrodes first decreased and then became higher, and there was a minimum point between 70 °C and 80 °C. This changing tendency was in accordance with the dependence of PD parameters on the oil temperature. In terms of the above results, the effects of temperature on PD frequency and breakdown voltage were discussed.

Effect of oil temperature and counterpart material on the wear mechanism of ta-CNx coating under base oil lubrication

Tetrahedral amorphous carbon nitride (ta-CNx), as an emerging and promising diamond-like carbon (DLC), has better mechanical properties than amorphous carbon nitride (a-CNx) to ensure the sufficient durability, and overcomes the limit of high internal stress of tetrahedral amorphous carbon (ta-C), which makes ta-CNx coatings of great worth of research for the tribological and mechanical applications. In this study, we present the effects of oil temperature and counterpart material on the wear behavior of ta-CNx coatings under base-oil lubrication, and further clarify the wear mechanism. ta-C and ta-CNx coatings with N/C atomic ratio of 2.2% and 11.0% were deposited by an ion beam assisted filtered arc deposition (IBA-FAD) system, and the tribological tests were performed using a ball-on-disk tribo-tester with ta-C and ta-CNx coated steel ball sliding against uncoated disk under base-oil lubrication. The results show that nitrogen doping tends to decrease the hardness and Young's modulus by reducing the sp3 structure. Sliding against steel disk, with increase of sliding distance ta-CNx shows obviously distinct wear behavior compared to ta-C, much more slowly increasing wear volume, exhibiting excellent wear resistance. Increasing oil temperature from room temperature to 120°C results in rising wear rates of all the three coatings, with totally worn out ta-C and much lower wear rate of ta-CNx, which decreases by more than half than ta-C for high nitrogen content ta-CNx. However, as the counterpart material changed from steel to alumina, the wear rate presents oppositely increasing tendency with N/C ratio, probably caused by the change of deciding factor to hardness in this mechanical wear. It is found that the wear performance of ta-CNx coating has a clear dependence on the oil temperature and counterpart material. Based on the results, the better wear resistance of softer ta-CNx against steel could be attributed to the less tribo-chemical wear between carbon and iron, due to the nitrogen doping partial passivation effect.

Experimental Study on Factors Affected Drag Torque of Hydro-viscous Clutch

The factors affected drag torque such as speed, oil temperature and clearance of friction pair are researched by test. The results indicate drag torque rises with increase of speed, drag torque reduces with increase of oil temperature and clearance of friction pair. The conclusion can be drawn which further research on drag torque of Hydro-viscous clutch should be carried on.

Degradation of fatty acids and tocopherols to form tocopheryl quinone as risk factor during microwave heating, pan‐frying and deep‐fat frying

We investigated degradation of tocopherols to form tocopheryl quinones (TQ) and cytotoxic γ‐tocopheryl quinone in oils and French fries during microwave heating, pan‐frying and deep‐fat frying. We proved that the microwave oven caused rapid increase of oil temperature, with the consequence of two to three times greater degradation of fatty acids and tocopherols than pan‐frying and deep‐fat frying. Pan‐frying with sunflower oil caused three‐time greater formation of fatty acids polymers, compare with rapeseed oil. The gentlest one was deep‐fat frying, which caused two times slower formation of fatty acid hydroperoxides and tocopheryl quinones in 900 g of oil. We found that not only the quantity but also the type of oil had critical effect on the formation of cytotoxic γ‐tocopheryl quinone. During 50 min of pan‐frying in rapeseed oil, 22 mg/kg of γ‐tocopheryl quinones was formed, of which 5–7 mg/kg penetrated into the homemade French fries. While the deep‐fat frying technique generated only 6 mg/kg of γ‐tocopheryl quinones in rapeseed oil. The rapid microwave heating caused formation of 8 mg/kg of γ‐tocopheryl quinones within 10 min. The emergence of γ‐tocopheryl quinones during culinary preparation of food has not yet been explored.Practical applications: Although an extensive research have been conducted in the area of microwave heating of foods, this is the first report about formation of cytotoxic γ‐tocopheryl quinone in microwave‐heated rapeseed oil. Formation of this reactive compound was also confirmed during frying process. The most γ‐tocopheryl quinone was formed during pan‐frying and subsequently entered into fried food. It was observed that the amount of oil used for frying has a major impact on slowing formation of cytotoxic γ‐tocopheryl quinone and other tocopherols and fatty acids degradation product.Formation of health‐promoting α‐tocopheryl quinone and cytotoxic γ‐tocopheryl quinone during pan‐frying.

Experimental Research of Forced Diesel Engine with Oil Temperature Control System in Cold Ambient Conditions

The article presents the results of experimental investigation of oil temperature control system as means of forced diesel engine (cylinder diameter – 150mm) cold start characteristics improvement. The effect of operating conditions and oil temperature control system design on the thermal state and the cold start characteristics of the diesel engine was determined experimentally (in “climate” chamber). It is proved, that the application of this system and coolant heater with the recommended design parameters and operating modes, ensures the diesel compliance with the requirements of normative and technical documentation, and allows increasing oil temperature in the main oil line (without coolant heating) by -10...23°C, in the crankcase – by 5...10°C, the average temperature of the diesel engine – by 7...8°C, before the start, providing a guaranteed engine start at ambient temperatures of -25°C within 5...8.5minutes, at -50°C – within 21...28min. The impact of the diesel engine start with coolant heater and oil temperature control system on the wear of engine parts is analyzed. It was established experimentally, that the main power and fuel consumption parameters of the engine meet the technical requirements. The condition of the engine parts friction surfaces, to which oil is supplied under pressure (crankshaft and camshaft, oil pump, etc.), is normal. This confirms the satisfactory condition of these parts lubrication in the cold start-up process.

An Experimental Investigation of the Torque Efficiency in Small Supr Gears

In present study, a gear transmission system was used to evaluate the effects of oil viscosity, speed, oil temperature as well as the applied load on torque efficiency. The experimental results reveal that the efficiency is increased with the increasing oil temperature and/or applied load whether the multigrade or singlegrade oil was employed. Under a constant torgue, the power loss is increased with the increasing pitch line velocity. The above characteristic resulting from the use of high-viscosity oil yields the substantial variations. However, as the oil film thickness is quite small, the viscosity speed, oil temperature and applied load produces the limited effect on torque efficiency, It indicate that EP additives create an opposite effect on torque efficiency at poor lubrication.

Characterization of asphaltene deposition in a stainless steel tube

In this study, the mechanism and kinetics of asphaltene deposition in stainless steel tubes have been studied experimentally using n-heptane as the precipitant. The effects of oil velocity, temperature, and oil–precipitant volumetric dilution ratio on the rate of asphaltene deposition are investigated. Since the adhesion of asphaltenes on to the metal surface is controlled by its transport through the laminar sub layer, our focus was limited to studying the phenomena in laminar flow regime. The concentration of asphaltenes was measured using UV–visible spectrophotometer at 650 nm wavelength. This enabled us to accurately measure the amount and extent of asphaltene deposits in the stainless steel tube. It is observed that the deposition process is often accompanied by significant erosion due to the subsequent dominance of shear forces on the asphaltene deposits. However, the erosion is not complete and a certain layer of asphaltene deposits remain before the deposition process becomes dominant. The initial rate of asphaltene deposition increases with the increase in oil velocity and temperature. The deposition rates increase with the decrease in the oil–precipitant volumetric dilution ratio. The asphaltene deposits were also subjected to X-ray photoelectron spectroscopy to characterize the surface composition of atoms responsible for the interfacial interaction forces due to the surface functional groups. The fundamental interaction forces between asphaltenes and a stainless steel surface was measured by using inverse gas chromatography. The surface energy of stainless steel indicated the amphoteric nature of the surface, with a slightly higher basic component. The surface energy of asphaltenes displayed a very high component of Lifshitz–van der Waals forces. However the polar component of surface energy of asphaltenes could not be measured due to its very strong interaction with the polar probes on account of its polarity.

Influence of carbon black in engine oil on wear of H-free diamond-like carbon coatings

Wear tests were conducted on hydrogen-free DLC coatings lubricated with engine oil containing carbon black (CB) in order to clarify their wear resistance. The influence of CB on accelerating wear was noticeable in the region where the minimum oil film thickness was less than the averaged secondary particle diameter of CB aggregates. According to a Raman spectroscopic analysis, the amount of DLC coating wear when lubricated in oil without CB tended to increase with increasing oil temperature and with an increasing Id/Ig ratio in the coating surface layer. In contrast, the Id/Ig ratio of the DLC coatings tested in oil containing CB tended to decrease, though the amount of DLC coating wear increased, which indicated a different wear mechanism.

J0540305 風力利用を想定した油圧式発熱システムの開発([J054-03]再生可能エネルギー(3))

The purposes of this study are to clarify the validity of the conversion of wind power into thermal energy by using the hydraulic heating system and to consider the optimal method of this system. An oil pump was driven by a DC-motor instead of wind turbine, and the oil increased in temperature by the pressure loss of orifices mounted in a heating element connected to the hydraulic circuit. The power consumed by pressure loss, the effective heating rate, and the oil temperature increase process were measured under several different conditions, for example the number of orifice plates and the space between its plates. As the results of these investigations, it was found that this oil hydraulic heating system using the pressure loss of orifices worked well for the wind power heater.

Study on the improvement in continuously variable transmission efficiency with a thermal management system

Recently, a thermal management system (TMS) was considered to improve fuel economy by reducing energy loss and parasitic energy. Furthermore, the TMS includes waste heat recovery (WHR), which warms up engine coolant or transmission oil and obtain electrical or mechanical energy. In particular, the TMS is necessary to resolve the drawback of hybrid electric vehicles (HEVs), as the transmission oil heats up more slowly compared to a conventional vehicle due to shorter engine operating time. In this report, a TMS with a WHR system was applied to supply heat source to the continuously variable transmission (CVT) oil of a HEV for a better operating region at the cold start condition. The research was performed using a simulation model, which consists of a thermal mass model, heat transfer model, friction model and waste heat recovery model with experimental data were used for validation. As a result, the simulation results showed that the CVT efficiency with the WHR model could be improved by as much as 2% with an oil temperature increase of 16 °C in the urban dynamometer driving schedule (UDDS) mode, and an additional 2–8% improvement in transmission efficiency could be achieved by expansion of the application area.

Quality and safety driven optimal operation of deep-fat frying of potato chips

Increasing oil temperature and heating duration in deep-fat frying of potato chips can improve textural quality but worsen the chemical safety of acrylamide formation. Optimal design of this complex process is formulated as a non-linear constrained optimization problem where the objective is to compute the oil temperature profile that guarantees the desired final moisture content while minimizing final acrylamide content subject to operating constraints and the process dynamics. The process dynamics uses a multicomponent and multiphase transport model in the potato as a porous medium taken from literature. Results show that five different heating zones offer a good compromise between process duration (shorter the better) and safety in terms of lower acrylamide formation. A short, high temperature zone at the beginning with a progressive decrease in zone temperatures was found to be the optimal design. The multi-zone optimal operating conditions show significant advantages over nominal constant temperature processes, opening new avenues for optimization.

Coeficientes Convectivos de Transferencia de Calor durante el Freído de Láminas de Tilapia (Oreochromis niloticus)

The convective heat transfer coefficients during deep-fat frying of Oreochromis niloticus fillets in palm oil at different temperatures were determined. Tilapia fillets were plate-shaped cut and dipped in oil at 130, 150, and 170 °C in an electric fryer six liter stainless steel. Thermophysical properties were measured as a function of temperature and composition of the food, using the computer program DEPROTER. The convective coefficients were determined from plots of time -vs- dimensionless temperature relationships, and these decreased with increasing oil temperature, with values of 46.76, 34.61 and 32.66 W/m