Traditional Mineral Oil Research Articles

The influence of self-lubricating coating during incremental sheet forming of TA1 sheet

Incremental sheet forming (ISF) is an advanced sheet forming process featured with great flexibility, enhanced formability, and high efficiency especially for small batch production. However, the poor surface finish and the large forming load are the main shortages of ISF, especially for the difficult-to-form materials such as titanium sheets. In the present work, a self-lubricating coating was successfully prepared on pure titanium substrates by the atmospheric plasma spraying (APS) process before the forming process for improving the lubrication condition. It was found that the friction is significantly reduced during the forming process when using the self-lubricating coating compared with that with traditional mineral oil as the lubricant. In addition, the wear rate suggests that components’ surface has self-lubrication coating after forming due to excellent wear resistance of the coating. Furthermore, a better external surface quality can be obtained when the friction resistance is lower since the friction plays a crucial role in material deformation. The tensile test suggests that the effect of heating on sheet mechanical properties is opposite to coating on that. Finally, the effects of coating on mechanical properties of the TA1 sheet were investigated and the appropriate parameters for spraying the self-lubricating coating were determined. The present work provides a novel method for enhancing the product quality in ISF through lubrication condition improvement.

Comparison of oil emulsion, mannosylated chitosan, and Bacillus vector adjuvants for vaccination against influenza in chickens

Summary Vaccination against influenza continues to be the primary method of control in many countries, but there is still a strong reliance on autogenous vaccines adjuvated with mineral oil emulsions known to induce overly high local inflammatory responses and lesions at the site of injection. The studies presented herein investigate various combinations of mannosylated chitosan adjuvant (MCA) and/or recombinant Bacillus construct adjuvant (BCA) containing highly conserved influenza antigens to assess their ability to function as an effective alternative adjuvant in influenza vaccination. In experiment 1, broilers were vaccinated via subcutaneous and/or drinking water application with an inactivated swine influenza in combination with MCA or commercial oil emulsion adjuvant. Subcutaneous or oral prime, followed by oral boost, resulted in the highest improvement in day 21 serum IgG hemagglutination inhibition (HI) titer, compared to the non-vaccinated control group. Experiment 2 tested BCA and MCA adjuvants, mixed with inactivated avian influenza virus in broilers. The group receiving combined subcutaneous and oral prime, followed by an oral boost containing both MCA and BCA adjuvants, exhibited significantly improved tracheal IgA HI titers. Experiment 3 investigated the ability of these adjuvated vaccines to protect against both homologous and heterologous highly pathogenic avian influenza challenge in layers. Groups receiving a subcutaneous prime followed by either subcutaneous or oral boost survived at 100%. Groups receiving only oral vaccine administrations did not exhibit improved survival. MCA and BCA adjuvants were found to improve immune responses in both broiler and layer-type chickens, equivalently matching immunogenicity and protection to the traditional mineral oil emulsion adjuvant. These studies suggest protective mucosal immunity can be achieved with vaccination strategies that incorporate MCA or BCA, but primary parenteral administration remains an important component of the vaccination strategy to achieve protective immunity.

Statistical Investigation of Lightning Impulse Breakdown Voltage of Natural and Synthetic Ester Oils-Based Fe3O4, Al2O3and SiO2Nanofluids

The characteristics of lighting impulse breakdown voltage (LI-BDV) constitute key performance indicators of insulating materials, especially in insulations based on liquids and liquid-paper for high voltage applications. Encouraged by environmental policies worldwide, new insulating liquids have been developed in recent years. Among these are natural and synthetic esters that are currently considered as potential substitutes for traditional mineral oils due to their environmentally friendly properties. Recent technological advances have shown that the addition of specific nanoparticles (NPs) to insulating liquids can improve both the dielectric withstand voltage and the thermal behavior of liquid insulations. This paper examines the effects of some NPs on the negative LI-BDV of natural and synthetic ester liquids, namely MIDEL 1204 and MIDEL 7131, respectively. The used NPs are Fe3O4, Al2O3 and SiO2. The LI-BDV measurements are executed in accordance with IEC 60060 standard, and the breakdown voltage with 1% probability risk (i.e., the lowest possible breakdown voltage) was also estimated. The experimental results showed that these NPs improved the LI-BDV of both synthetic and natural ester liquids and an optimal concentration of NPs can be determined. Statistical analysis was also performed to check the compliance of the experimental results with the most common probability distributions, normal and Weibull distributions.

Effects of palm-based trimethylolpropane ester/mineral oil blending on dielectric properties and oxidative stability of transformer insulating liquid

Blending of palm-based ester can effectively increase the flash point and thermal-oxidative stability of mineral transformer oil especially in the event of high loading and high temperature. Inversely, owing to the excellent dielectric properties of mineral oil, the dielectric properties of the esters can also be improved. Thus, high oleic palm-based trimethylolpropane (TMP) ester was blended and homogenized with 20 to 50 % of mineral oil, and the physico-chemical and electrical properties of each base fluid was compared with that of pure TMP ester and pure mineral oil. The samples were also subjected to oxidative stability test conducted at 95°C for 500 hours, with the presence of water, oxygen and copper/steel catalyst. During ester and mineral oil degradations, the oxidized oils take on dark brown color with the increase in oxidation products concentration and the sludge formation due to the reaction between the oil and the metal catalyst. XRF measurements performed on the samples showed an increase in iron and sulfur contents, which can be explained by the formation of superficial surface layer of iron (II) sulfide or ferrous sulfide. From the investigations, it was found that the 80/20 of ester/mineral oil blending sample have properties near to the standard values for transformer liquid insulation; thus, it can potentially replace traditional mineral oil as an alternate liquid insulation.

Review of Research Progress on the Electrical Properties and Modification of Mineral Insulating Oils Used in Power Transformers

In November 2017, the first ±1100 kV high-voltage direct-current power transformer in the world, which was made by Siemens in Nurnberg, passed its type test. Meanwhile, in early 2017, a ±1000 kV ultra-high voltage (UHV) substation was officially put into operation in Tianjin, China. These examples illustrate that the era of UHV power transmission is coming. With the rapid increase in power transmission voltage, the performance requirements for the insulation of power transformers are getting higher and higher. The traditional mineral oils used inside power transformers as insulating and cooling agents are thus facing a serious challenge to meet these requirements. In this review, the basic properties of traditional mineral insulating oil are first introduced. Then, the variation of electrical properties such as breakdown strength, permittivity, and conductivity during transformer operation and aging is summarized. Next, the modification of mineral insulating oil is investigated with a focus on the influence of nanoparticles on the electrical properties of nano-modified insulating oil. Recent studies on the performance of mineral oil at molecular and atomic levels by molecular dynamics simulations are then described. Finally, future research hotspots and notable research topics are discussed.

Natural esters for life and capacity enhancement of distribution transformers

Ageing assets of any electrical utility are a reality; the challenge is not in replacing these assets by incurring huge capital expenditure but in enhancing the life of existing assets. This involves re-engineering of existing installations by developing retrofit solutions so as to accommodate the reengineered solutions in the existing space and at a substantially reduced capital expenditure. Retro filling of mineral oil filled transformers by natural esters has given multiple benefits of enhanced fire safety, enhanced life of the paper by virtue of the fact that natural esters have an inherent property of absorbing moisture from the paper insulation that is impregnated with, further the temperature rise offered by natural esters are higher than that by mineral oil. Tata Power has adopted the best practice of retro filling mineral oil filled transformers that are optimally loaded and more than 15 years old with natural esters. Condition monitoring of these transformers over a period of time has clearly depicted that retro filling of distribution transformers by replacing traditional mineral oil with natural ester oil is a financially viable solution for enhancement of transformer capacity, life, safety, & environment friendly.

Comparative analysis of air-gap PD characteristics: Vegetable oil/pressboard and mineral oil/pressboard

Partial Discharge (PD) is considered to be one of the main reasons for aging and degradation of the oil/pressboard insulation system in power transformers. Vegetable oils which own excellent dielectric performance are introduced as potential insulation liquids substituting traditional mineral oil. In this paper, an air-gap PD model was adopted to investigate the PD characteristics of refined rapeseed oil and Karamay 25# mineral oil that are both currently employed in liquid filled power transformers. The PD current pulse waveform analysis (PD-CPWA) method was used to investigate PD mechanisms of two different insulation systems: mineral oil/pressboard and vegetable oil/pressboard. For both insulation systems, phase resolved partial discharge (PRPD) patterns throughout the accelerated deterioration experiments were compared. The extracted ϕ-q-n plots with respect to various PD times were analyzed. It is found that, the air-gap PD stage characteristics of vegetable oil/pressboard are more notable. It has fewer double-peak pulses, smaller inception phase angle, lower charge amplitude, higher repetition rate, and more remarkable ‘rabbit-ear’ patterns than mineral oil/pressboard. The PD development process of both insulation systems can be characterized by four stages: initial discharge stage, weak developing stage, discharge burst stage and pre-breakdown stage.

Investigations on Eco Friendly Insulating Fluids from Rapeseed and Pongamia Pinnata Oils for Power Transformer Applications

Transformer mineral oil which is normally hydrocarbon based is non- biodegradable and pollutes the environment in all aspects. Though vegetable oils are eco-friendly in nature and potentially could be used in transformers as a replacement for the mineral oil, there usage is restricted because of their oxidative instability. The present work focuses on using rapeseed oil and pongamia (pongamia pinnata) oil as effective alternatives for the traditional mineral oil in power transformer. The oxidative stability of the rapeseed oil and pongamia oil is increased by using combinations of the natural and synthetic anti-oxidants as additives. The parameters like breakdown voltage, viscosity, flash point, fire point are measured for the rapeseed oil and pongamia oil with and without the additives as per IEC and ASTM standards. The results shown encouraging changes in the parameter values and ensures the use of the oils as a potential alternative insulation in power transformers.

Impact of local overheating on conventional and hybrid insulations for power transformers

For more than a century, conventional mineral oil/cellulose insulation is being used as main insulation for power transformers. The life span of these major assets is determined amongst others by the insulation system’s mechanical resistance to withstand short circuit current forces. Since cellulose paper aging is accelerated by temperature, moisture and oxygen, poly-aramid-based synthetic insulation paper, with better thermal stability emerged for application in transformers. However the relatively limited number of studies on hybrid insulation and the cost of aramid paper still limit their use in distribution transformers. This contribution attempts to demonstrate that despite the high cost of aramid paper, hybrid insulation could be used in large power transformers which represent a significant financial investment. To do this, the quality of mineral oil aged with hybrid solid insulation and the thermal aging of the cellulose paper of this insulation are investigated. Comparison was made with traditional mineral oil impregnated cellulose paper to provide a benchmark for comparison. The samples underwent thermal accelerated aging procedure according to ASTM-D1934 standard and, furthermore, were submitted to local overheating. The condition of oil samples collected from each aging vessel was assessed using several diagnostic techniques, namely the relative amount of the Dissolved Decay Products (DDP), Turbidity, and Interfacial Tension (IFT). The Degree of Polymerisation (DPv) and Dissolved gas Analysis (DGA) were used to monitor the thermal aging of the cellulose paper samples. The results indicate that oil aged with hybrid solid insulation yield fewer decay products at some aging stages, especially after the application of a local overheating. The results also indicate that the cellulose paper within solid hybrid insulation is slightly less degraded compared to that of conventional insulation.

Numerical analysis of local hot-spot temperatures in transformer windings by using alternative dielectric fluids

This paper deals with the thermal characteristics of traditional mineral oil and alternative dielectric fluids. Candidates of alternative dielectric fluids used in the transformer were silicon oil, HMWH, synthetic ester and natural ester. In this study, the transformer which uses synthetic ester and natural ester was focused. 3 ph, 66 kV, 16.5 MVA power transformer and 3 ph, 22 kV, 2.3 MVA distribution transformer were considered and compared the hot-spot temperatures and top oil temperatures by using the computational fluid dynamics (CFD). Kinematic viscosities of natural ester and synthetic ester were four times and three times higher than the mineral oil at the working temperature of \(60\,^{\circ }\hbox {C}\) respectively. The flow rate of natural ester and synthetic ester was 50–40 % decreased. Therefore, the hot-spot temperature of natural ester and synthetic ester was 24 and 14 % higher than the use of mineral oil respectively.

Pongamia Pinnata as Alternate Liquid Dielectrics in Distribution Transformer: A Critical Study on the Property of Viscosity

Distribution Transformers are one of the imperative equipment in power system. The insulation design has an important role because it continuously energizes in a day. Due to electro mechanical stresses the operating temperature of distribution transformer will be increased which maintains with in limit using liquid dielectrics. Traditional mineral oil is used as liquid dielectrics in Distribution Transformer. Due to lack of fossil fuels and lesser biodegradability characteristics of mineral oil, the alternating liquid dielectrics are important. In this research work viscosity of pongamia pinnata oil is measured using PLINT TE 62 Bench Viscometer as per ASTM D445 standard .Water content analysis of the oil sample has to be measured by weight balance method and Breakdown strength of oil sample was measured by Nutronics oil test set as per IEC 60156. From the experimental analysis, the viscosity of pongamia pinnata oil is low as compared to RBDPO, Soyabean oil, Coconut oil and Sunflower oil. The moisture content of pongamia pinnata oil is significantly reduced during aging period and the average breakdown strength of pongamia pinnata oil is higher than that of conventionally used mineral oil.

Machinability Characteristics of Wrought and EBM CoCrMo Alloys

The Electron Beam Melting (EBM) CoCrMo alloy is currently utilized for the production of joint replacements and fixation devices thanks to its high strength, good wear and corrosion resistance, and excellent biocompatibility. Even if its use in the biomedical sector is intensive and it is usually subjected to various machining operations for the implants production after the rapid manufacturing step, the scientific literature lacks of comprehensive data about its machinability. Therefore, the objective of the paper is to investigate the machinability characteristics of the EBM CoCrMo alloy and compare it with the machinability of the wrought CoCrMo. Semi-finishing external turning tests were performed using a commercial TiAlN coated tungsten carbide insert under a traditional mineral oil and water emulsion lubricating condition. Tool wear, surface integrity, and microstructure material analysis evidenced that the EBM alloy is more difficult to machine due to a more abrasive microstructure.

English

The paper predicts the exceptional extreme pressure properties of multi walled carbon nano tube as compared with traditional mineral oil which also contained some additives and graphite. The extreme pressure property was predicted by four ball tester. In the test the load bearing capacity of the newly developed nano oil was predicted to have a better value than the commercial available mineral oil. The weld load of the nanolubricant was found to be 200 kgf as compared with the base mineral oil which got welded at 160 kgf. Thus, the finding would be helpful in developing new nanolubricants which would increase the life of the mating parts, reducing the chances of failure of machine and increasing the productivity. Key words: Mineral oil, multi walled carbon nano tube (MWCNT), pass load, weld load, load bearing capacity, Carbon Nano Tubes (CNT).

Effects of reduced pressure and additives on streamers in white oil in long point-plane gap

Recent experiments show that modern dielectric liquids behave differently from traditional mineral oil, particularly with respect to breakdown voltages for lightning impulse. This paper describes an experimental investigation addressing underlying reasons for this. The influences of reduced pressure and additives on streamers in white oil were investigated under both positive and negative polarities using an 8 cm long point-plane gap. Reduced pressure significantly accelerates streamers, thus increasing stopping length and reducing both breakdown and acceleration voltages. With increasing applied voltage, different typical propagation modes of streamers were recorded for both polarities. A low ionization potential additive strongly affects positive streamers. It significantly changes streamer velocity and reduces the breakdown voltage but increases the acceleration voltage where breakdown streamer velocity increases drastically. Adding an electron scavenger influences streamers of both polarities, but it mainly increases the velocity of negative streamers and results in a reduction of both the breakdown and the acceleration voltages. The propagation mechanisms of streamers are also discussed.

Enhancing the critical characteristics of natural esters with antioxidants for power transformer applications

The energy demand of the whole world is dominated by petroleum products for centuries in the field of critical application like electricity. The application of mineral oil in power system equipment like transformer is potentially hazardous to environment. The exploitation of petroleum oil is running out of demand and in the near future, oil scarcity exists. This work focuses in identifying alternate dielectric for replacing traditional mineral oil. India is a tropical country, which produces vegetable oils like sunflower oil, palm oil, coconut oil, mustard oil, corn oil, soybean oil and rice bran oil profusely and it can be used as dielectric fluids in transformer. To be more proficient in the operation of transformer, these vegetable oils should be converted in to superior dielectric fluids. This work also embraces the individual and combinatorial effect of selected natural and synthetic antioxidants in natural ester. For investigation sunflower oil, rice bran oil, soybean oil and corn oil are chosen. The critical parameters like breakdown voltage, viscosity, flash point and fire point are calculated according to IEC and ASTM standards before and after addition of antioxidants with vegetable oils. Astoundingly it is found that the use of natural and synthetic antioxidants can enhance the critical parameters of natural ester for transformer application and the antioxidant activity in the natural ester is discussed. The interpolation functions are calculated based on the results obtained in minimum and maximum concentration of antioxidant added. These functions are used to predict the intermediate output variations caused for each antioxidant concentrations (in gram).

Electrochemical detection of trace cadmium in soil using a Nafion/stannum film-modified molecular wire carbon paste electrodes

In this paper, a novel Nafion polymer-coated stannum film-modified carbon paste electrode was developed for the analysis of trace cadmium by square wave anodic stripping voltammetry. The electronic conductive material—molecular wire (diphenylacetylene)—was employed as the binder instead of traditional mineral oil for fabricating this electrode. It was found that the prepared electrode possessed excellent electrochemical performance and increased electron transfer rate due to the introduction of molecular wire as a binder, and exhibited a better sensitivity and stability as well as high resistance to surfactants due to the synergistic effect of Nafion and stannum film. Under the optimal conditions, the stripping peak currents showed a good linear relationship with the Cd(II) concentration in the range from 1.0 to 80.0 μg L−1 with a detection limit of 0.13 μg L−1 (S/N = 3). The developed electrode was further applied to the determination of Cd(II) in soil extracts with satisfactory results.

Die-sinking electrical discharge machining with oxygen-mixed water-in-oil emulsion working fluid

Water-in-oil emulsion has been proposed as the working fluid of die-sinking electrical discharge machining in our previous research. Compared with the traditional mineral oil–based working fluid, the water-in-oil emulsion was more environmentally benign and efficiency. This study presents a new method of die-sinking electrical discharge machining that uses oxygen-mixed water-in-oil emulsion as the working fluid. Experimental results showed that the material removal rate can be highly improved, and the relative electrode wear ratio can be significantly reduced by mixing oxygen into the water-in-oil emulsion. The recast layer was much thinner with this oxygen-assisted machining method.

The ohmic resistance effect for characterisation of carbon nanotube paste electrodes (CNTPEs)

In this study, carbon nanotube paste electrodes (CNTPEs) have been characterised using their ohmic resistance, RCNTPE, when examining a set of six different electrodes prepared from three types of CNTs and two altered pasting liquids (binders); the latter represented by traditional mineral or silicone oils. It is shown that simple measurements of the ohmic resistance can alternate to the standard electrochemical characterisation by cyclic voltammetry with model systems. During the proper experimentation, particular attention has been paid to the changes of the consistency and of the resultant RCNTPE in dependence of both main constituents used and upon the carbon-to-pasting liquid ratio chosen. The results obtained were compared to those of “classical” carbon paste electrodes (CPEs) prepared from common graphite powder. The most evident and surprising difference ascertained is associated with the optimal carbon-to-pasting liquid: whereas the ordinary CPEs could contain up to 20% (w/w) oily phase, the CNTPEs reached the optimum at about 60% (w/w) binder, while retaining still satisfactory physical as well as electrochemical properties. The explanation of this finding is given and the problems connected with homogeneity and stability of various carbon pastes are discussed.

Aging Performance and Moisture Solubility of Vegetable Oils for Power Transformers

This paper discusses the suitability of vegetable oil as an insulating medium in power transformers. A high flash point and very good environmental compatibility compared to conventional mineral oil are good reasons to use vegetable oil in power transformers. In this paper, the physical and electrical performance and the aging behaviour of three natural vegetable oils are compared to one synthetic and one traditional mineral oil. The breakdown voltage of new, dry, natural vegetable oil is more than 80 kV, which is above the breakdown voltage of mineral oil. Regarding the aging of paper, natural esters are more friendly toward paper than mineral oil. The water solubility clearly exceeds that of mineral oil but the same dependence of dielectric parameters on relative moisture saturation was observed for all liquids. Aging of vegetable oils under the presence of air leads to oxidation and, thus, to a strong increase of viscosity. Therefore, transformers filled with these liquids need to exclude oxygen from air. The conducted experiments show vegetable oil to be applicable for use in power transformers.

PρT Experimental Measurements and Data Correlation of Pentaerythritol Esters

The new refrigerant fluids are generally not compatible with traditional mineral oils used for the lubrification of compressors. Different typologies of oils have been proposed, such as polyalkylene glycol (PAG), alkylbenzene (AB), and polyol ester (POE) oils. New thermodynamic models are necessary to describe well the behavior of these fluids, but at the moment only few experimental data are available in the literature. The work presented in this paper is part of our research program aimed to evaluate the solubility of refrigerants in commercial oils. The density of five different pentaerythritol esters is presented, which are used as components of the commercial POE oils (i.e., pentaerythritol ester of butyric acid (PEC4), pentaerythritol ester of valeric acid (PEC5), pentaerythritol ester of hexanoic acid (PEC6), pentaerythritol ester of heptanoic acid (PEC7), and pentaerythritol ester of octanoic acid (PEC8)). The experimental compressed liquid density data were correlated by means of a particular equ...