Oil Flow Rate Research Articles

Numerical and experimental thermofluid investigation of different disc-type power transformer winding arrangements

In this paper, measurements are carried out on four different washer arrangements of an ON disc-type power transformer winding scale model. The experimental setup comprises a closed cooling loop with all the main components generally found on a power transformer and it is equipped with both thermal and flow sensors. Moreover, 3D Conjugate Heat Transfer simulations of the entire cooling circuit are performed using a commercial CFD solver and the computed oil flow rates and winding temperatures are compared with the experimental data for both uniform and non-uniform heat loss distributions. The experimental results show that the reduction of the number of washers in the tested scale model winding increases the total oil flow rate but this effect is overridden by a higher flow maldistribution in the radial ducts of a pass. Thus, the discs temperatures increase with the removal of washers and this effect is particularly marked for a non-guided winding arrangement where an almost stagnant flow is observed in several radial cooling ducts. The CFD results show the same trend but the numerical model consistently underpredicts the total oil flow rate circulating in the closed cooling circuit. This underestimation by the CFD model causes, for certain winding arrangements, significant errors in the evaluation of the average and hot-spot temperatures. For this reason, numerical simulations with a reduced computational domain (i.e., winding region only) are also performed by specifying the measured oil flow rate and temperature as inlet boundary conditions. In this case, the accuracy of the numerical model is significantly improved as the predicted average and hot-spot winding temperatures are within 3 °C of the corresponding measured values. This result is reassuring since the majority of published numerical thermofuid studies on transformer windings are performed on the windings region only and boundary conditions are specified at the inlet, thus avoiding the simulation of the entire cooling loop.

FEATURES OF APPLICATION OF MODEL OF THE STATIONARY TWO-PHASE FILTRATION FOR OIL FIELDS DEVELOPMENT

The article discusses the differential equation of the stationary two-phase filtration, the obtained as a spe-cial case of nonlinear non-stationary equations. It is established that for the formulation of solutions it is necessary to use the dependence of water-saturation and oil-saturation factors on the pressure of water pumped into the reservoir. With the advance bringing into the development of the injection well, it has been established, that the water and oil flow rates and the water-cut coefficient depend on the selected coefficients of the relative permeability and the outer boundary of the drainage area. The merits and demerits of the stationary filtration model are estimated.

Analysis of BJ493 diesel engine lubrication system properties

The BJ493ZLQ4A diesel engine design is based on the primary model of BJ493ZLQ3, of which exhaust level is upgraded to the National GB5 standard due to the improved design of combustion and injection systems. Given the above changes in the diesel lubrication system, its improved properties are analyzed in this paper. According to the structures, technical parameters and indices of the lubrication system, the lubrication system model of BJ493ZLQ4A diesel engine was constructed using the Flowmaster flow simulation software. The properties of the diesel engine lubrication system, such as the oil flow rate and pressure at different rotational speeds were analyzed for the schemes involving large- and small-scale oil filters. The calculated values of the main oil channel pressure are in good agreement with the experimental results, which verifies the proposed model feasibility. The calculation results show that the main oil channel pressure and maximum oil flow rate values for the large-scale oil filter scheme satisfy the design requirements, while the small-scale scheme yields too low main oil channel’s pressure and too high. Therefore, application of small-scale oil filters is hazardous, and the large-scale scheme is recommended.

Studying the Effect of Load Direction Variation on the Performance of Three Tilted Pads Journal Bearing

This research studied, theoretically, the performance of a tilted pad journal bearing. This bearing consists three inclined pads. These pads are distributed circumferentially around the journal. These pads can be adjusted in two ways: by changing the tilt angle of each pad _and by changing the circumferential position of the pads around the journal, relative to the external load direction, in order to obtain the following goals: (1) Maximum external load, (2) Maximum oil flow rate in order to carry out as much heat as possible, (3) Minimum power consumption, and (4) Control the attitude angle magnitude in order to control the stiffness and damping coefficients then improve bearing stability. The thickness of the oil film between the pads and the shaft surface had been obtained using an equation that was derived specially for this purpose. Then the pressure of each point on the three pads surfaces were also calculated using Reynolds equation which solved numerically using a computer program. The results showed that there is a certain direction for the external load (a specific value for

Application viability evaluation of the Minimum Quantity Lubrication coolant technique under different flow rates in Plunge Cylindrical Grinding of the ABNT 4340 steel with aluminum oxide wheel

Abstract The coolant delivery technique known as Minimal Quantity Lubrication (MQL) has been employed in machining since the end of the 20th Century and has gained considerable evidence in the last years as a viable alternative to the use of the conventional coolant technique (flood). Due to the low oil flow rate delivered by the MQL technique in grinding operations, that generally varies from 20 to 240 ml / h in relation to near 600,000 ml / h flow rate of the conventional coolant technique, the MQL technique provides a reduced risk for human health and environmental damage associated with the use, maintenance and disposal of cutting fluids. In this context, this study was carried out to evaluate the application viability of the minimum quantity lubrication coolant technique under different flow rates in the plunge cylindrical grinding of ABNT 4340 steel with an aluminum oxide wheel. Three flow rates were tested: 30, 60 and 120 ml/h. Grinding trials with the conventional coolant delivery method were also tested for comparative purposes. The output variables used to assess the efficiency of the MQL technique in this work are: roughness, roundness and hardness of the workpiece. Grinding wheel wear and power consumption were also monitored. The results showed that, despite the higher values of roughness and roundness of the workpiece, as well as the grinding wheel wear, the values of these same parameters obtained after machining with the MQL technique were close to those obtained after machining with the conventional technique. No thermal damages and cracks on the machined surface, or even below the machined surface, were observed after grinding ABNT 4340 steel irrespective of the coolant-lubrication condition investigated. The results showed that the MQL with 120 ml/h can be an alternative coolant technique due to cleaner environment and lower consumption of fluid in grinding under the conditions investigated in this work.

Experimental and numerical analysis of a self-circulating oil bearing system for gear pumps

PurposeFor moderate pressure and high pressure gear pumps, the temperature failure problem of bearings is now of considerable concern because of their heavy loads. However, the compact structure and the efficiency consideration make it extremely difficult to improve the bearing cooling. A self-circulating oil bearing system is developed for gear pumps with self-lubricating bearings to solve this problem. The oil is aspirated in from the low pressure chamber of the gear pump and discharged to the same chamber by using the pressure difference in the journal bearing, thus achieving the self-circulation.Design/methodology/approachAn experiment test rig has been built for the feasibility study. The oil flow rate under different speeds has been recorded. Furthermore, the temperatures of the bearings with or without the oil circulation have been compared. Additionally, the oil flow in the test rig has been simulated using computational fluid dynamics codes.FindingsThe experimental and numerical results agree well. The experimental results indicate that the oil flow rate increases approximately linearly with the speed and the bearing temperature can be lowered successfully. The calculation results indicate that the bearing load capacity is nearly the same. Both the experimental and numerical studies establish that the self-circulating oil bearing system works successfully.Originality valueAs far as the authors know, it is the first time to find that the self-circulation can be built using the pressure difference in the bearing oil film, and this principle can be applied in the cooling and lubrication of the gear pumps to solve the temperature failure problem.

Asphaltene deposition during flow through pipes: Parametric and inhibition analyses

ABSTRACTAsphaltene deposition is known as one of the problematic topics in petroleum engineering which is caused by changing pressure, temperature, and composition. So it becomes important to investigate the effect of different parameters such as precipitant to oil volume ratio, temperature, and flow rate. For this purpose, flow loop deposition set up was constructed and the pressure drop changes along tube were measured during experimental and this enhancement of pressure drop during the time illustrates deposition occurred. the results showed that increasing precipitant to oil volume ratio and temperature causes increasing deposition and as flow rate increases, the mass of deposits decreases because of increasing the shear rate on the wall of the tube. The novelty of this study is using CTAB and Benzoic acid inhibitors in this flow loop setup. It was observed the CTAB has more impact on inhibition of asphaltene deposition through the tube than a Benzoic acid inhibitor.

Design and numerical simulation on an auto-cumulative flowmeter in horizontal oil-water two-phase flow.

In order to accurately measure the flow rate under the low yield horizontal well conditions, an auto-cumulative flowmeter (ACF) was proposed. Using the proposed flowmeter, the oil flow rate in horizontal oil-water two-phase segregated flow can be finely extracted. The computational fluid dynamics software Fluent was used to simulate the fluid of the ACF in oil-water two-phase flow. In order to calibrate the simulation measurement of the ACF, a novel oil flow rate measurement method was further proposed. The models of the ACF were simulated to obtain and calibrate the oil flow rate under different total flow rates and oil cuts. Using the finite-element method, the structure of the seven conductance probes in the ACF was simulated. The response values for the probes of the ACF under the conditions of oil-water segregated flow were obtained. The experiments for oil-water segregated flow under different heights of the oil accumulation in horizontal oil-water two-phase flow were carried out to calibrate the ACF. The validity of the oil flow rate measurement in horizontal oil-water two-phase flow was verified by simulation and experimental results.

Characterization of droplet sizes in large scale oil–water flow downstream from a globe valve

Oil–water dispersed flows produced at valves or restrictions are very common in industry. For example, crude oil desalting processes normally use dispersion valves to mix the dilution water. In this case, the knowledge of dispersed droplet sizes is crucial for the design and optimum control of the process. However, little work has been devoted to characterize and model droplet sizes produced in industrial-type valves. The present work studies water droplet sizes produced by the passage of oil–water flow through a globe valve mounted in a large scale flow loop of 0.1 m internal diameter. Experiments were performed under different pressure drops across the globe valve, and different oil and water flow rates. Produced water droplet sizes were measured in situ downstream from the globe valve location using particle video microscopy. Droplet sizes were compared with theoretical scales for turbulent and viscous break-up. The effect of the volume fraction of dispersed phase on droplet size was also examined. In addition, droplet size distributions were analyzed and fitted using known statistical functions.

Pyrolysis of Palm Oil in a Continuous Flow Microchannel Reactor

Palm oil is considered as a potential feedstock for biofuel production in Thailand due to its property and availability. In recent years, there has been an increased attention on upgrading of palm oil to biofuels using various technologies. One of the most promising technologies is pyrolysis, in which palm oil is heated at the temperature in the range of 400 to 500 °C under oxygen-free atmosphere. In the present study, the uncoated catalyst and coated catalyst pyrolysis processes of palm oil for biofuel production in a continuous flow microchannel reactor were investigated with various catalyst types (MgO, Al2O3) at 400-500 °C, 2 ml/hr palm oil flow rate, and 0.1 g of catalysts. Liquid product yield, solid product yield and gaseous product yield were determined. The obtained results revealed that the high triglyceride conversion could be achieved at a short reaction time in microchannel reactor, which attributed to the enhancement of both heat and mass transfer. The pyrolysis liquid products composed of hydrocarbons, free fatty acids, and other oxygenated compounds which are the results of triglyceride cracking. Furthermore, product selectivity of palm oil pyrolysis depended on temperature and catalyst type.

Performance investigation of a pressure pulsation dampener applied in the discharge chamber of a twin screw refrigeration compressor

Intermittent gas flow generates pressure oscillations in the twin-screw refrigeration compressor that cause serious problems such as structural vibration and noise. In order to reduce the amplitude of this pressure pulsation, a pressure pulsation dampener (PPD) applied in the discharge chamber of a twin screw refrigeration compressor was proposed based on the theory of Helmholtz resonator. A mathematical model was developed to design an optimal PPD by incorporating the R134-oil mixture sound speed model and the pressure pulsation simulation model. A comprehensive experimental study was then performed to validate the model and evaluate the effect of key parameters such as oil flow rate and cavity volume on attenuation performance of the PPD. Vibrational characteristics of the compressor equipped with and without the PPD were also measured and compared. Under the design frequency of 250 Hz, the vibrational acceleration of compressor under-chassis reduced by 36.2% to 41.1% when the compressor was fitted with the proposed PPD.

Computational fluid dynamics analysis of MQL spray parameters and its influence on superalloy grinding

ABSTRACTThe application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. To sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel–work interface. The present work aims to develop a numerical model to replicate the mist formation in minimum quantity lubrication (MQL) grinding using a fluent-based computational fluid dynamics (CFD) flow solver. The MQL parameters considered for this study are air pressure and the mass flow rate. Simulation of the atomization under turbulent conditions was done in a discrete phase model (DPM) owing to the fact that oil mass flow rates are very low and oil acts as a discrete medium in air. Jet velocity and droplet diameters were also obtained under different input conditions to find the optimum value of air pressure and mass flow rate of oil to achieve the desired results (lower cutting force and surface roughness) in MQL grinding of superalloy (Inconel 751). It is seen that medium size (around 16.3 µm) of droplet plays a significant role in improved performance by the way of reduction in cutting force and surface roughness.

Milling performance optimization of DD5 Ni-based single-crystal superalloy

DD5 Ni-based single-crystal superalloy has presented a wide application prospect in aerospace, marine, nuclear reactor, and chemical industries due to its excellent comprehensive performances caused by the crystal boundary as the crack source complete elimination. However, because of the low thermal conductivity and strong adhesion characteristic, DD5 is difficult to machine and the research on this field is still blank. Therefore, the purpose of this paper is to investigate the material machining mechanism and optimize the milling performance. Based on the DD5 metallographic structure characteristics, the directional cutting method was proposed firstly. Then, considering the wear characteristic and failure mode of the tools with different coating materials, the milling tool proper selection was executed. Moreover, combining with the molecular dynamics (MD) simulation, slot milling experiments, and slip system theory, the best milling path was confirmed. In addition, considering the machining environmental sustainability, the milling performances acquired under the dry, minimal quantity lubrication (MQL) and water-based MQL conditions were evaluated and compared. Finally, in order to optimize the machining parameter sequence quantitatively and ascertain the milling and cooling interactive effect mechanism, response surface method (RSM), back-propagation artificial neural network (BP-ANN), genetic algorithm (GA), and uniform design experiments were all adopted. With the anticipation to improve environmental sustainability and milling performance simultaneously, the milling experiments on the DD5 (001) crystal plane along the [110] crystal direction under the water-based MQL technology with PVD-TiAlN-coated tools were conducted and the parameters of main spindle linear speed v c = 20 m/min, tool feed per tooth f = 8.97 μm, oil flow rate Q = 68.21 ml/h, the ratio of water and oil R = 0.94 and the air pressure P = 1.79 bar were used. Then, the better surface roughness Sa = 2.05 μm and the lower milling force F = 14.38 N can be acquired simultaneously based on the verification of the uniform design experiment results.

Characterization and Optimization of Machinability and Environmental Impact of Machining of Ti-6Al-4V with Minimum Quantity Lubrication

Minimum quantity lubrication has gained recent importance in high speed machining. However, more understanding and optimization of the MQL parameters remains a challenge to improve its performance. The main objective of this paper is to study the environmental impact and the machining performance of Minimum Quantity Lubrication (MQL) in milling of Ti-6Al-4V. In this paper, the effect of MQL parameters; namely oil and air flow rate, nozzle orientation and nozzle distance on the machining performance was investigated and compared to flood and dry milling of titanium alloys. The machining performance was evaluated in terms of cutting forces, surface roughness and tool temperature. It was found that better machining performance and environmental impact was obtained using an optimized MQL jet.

Influence of Water and Mineral Oil on the Leaks in Satellite Motor Commutation Unit Clearances

Abstract The article describes the flow rates of mineral oil and water flowing, as working media, through the commutation unit of a hydraulic satellite motor. It is demonstrated that geometrical dimensions of commutation unit clearances change as a function of the machine shaft rotation angle. Methods for measuring the rate of this flow and the pressure in the working chamber are presented. The results of pressure measurements in the working chamber during the transition from the filling cycle to the emptying cycle are included. The pressure in the motor’s working chamber changes linearly as a function of the shaft rotation angle, which has a significant effect on the leakage in the commutation unit clearances. The paper presents new mathematical formulas in the form: Q=f(Δpγ) to calculate the flow rate of water and mineral oil in the commutation unit clearances. The γ factor is described as a function of fluid viscosity and clearance length (the motor shaft rotation angle). The coefficients used in these formulas were determined based on the results of laboratory tests of a motor supplied with water and mineral oil.

Experimental investigation on power generation with low grade waste heat and CO2 transcritical power cycle

In this study, a small-scale test rig of CO2 transcritical power cycle (T-CO2) system driven by low-grade heat has been developed and investigated experimentally. The test rig consists of a number of essential components including a CO2 turboexpander with high speed generator, finned-tube air cooled condenser, liquid receiver, CO2 liquid pump and CO2 gas generator. The CO2 is heated in the plate-type gas generator by hot thermal oil flow which is circulated and heated by exhaust flue gases from an 80kWemicroturbine CHP unit. The test rig has been fully commissioned, instrumented, controlled and is ready to operate experiment as required. Subsequently, at constant heat sink (ambient) and heat source (thermal oil) temperatures, a series of experiments have been carried out to examine the effects of various important parameters on the T-CO2 system performance. These include thermal oil flow rate and CO2 mass flow rate etc. Preliminary experimental results show that the CO2 TPC is applicable for the low temperature heat sources to generate power although further efficiency improvements are needed. In addition, the experimental outcomes can instruct future optimal system design and controls.

Dynamic formation and scaling law of hollow droplet with gas/oil/water system in dual‐coaxial microfluidic devices

Based on the one‐step microfluidic method of producing hollow droplet with thin film, this article studies the effect of water and oil flow rate, gas pressure, and viscosity of aqueous phase on the dynamic formation and size of hollow droplet by analyzing large amounts of data acquired automatically. The results show that the filling stage of hollow droplet is similar to that of microbubble formation, while the necking stage is similar to that of droplet formation process. Furthermore, based on the data and mathematical model describing droplet formation mechanism, a filling stage model including Capillary number of continuous phase is developed. Considering the dynamic interface breakup and displacement of droplet in necking stage, a necking stage model is developed. The results show that the model results considering filling and necking stage fit well with the experimental data, and the relative error is less than 5%. Finally, the same model with parameters is used to predict the size of hollow droplet with other systems and devices, and the model is proved to be relative precise in our experimental conditions. The results presented in this work provide a more in‐depth understanding of the dynamic formation and scaling law of hollow droplet with G/L/L systems in microfluidic devices. © 2017 American Institute of Chemical Engineers AIChE J, 64: 730–739, 2018

Toward gene expression programming for accurate prognostication of the critical oil flow rate through the choke: correlation development

AbstractIn this study, gene expression programming (GEP) was employed to develop a new equation for calculating choke flow rate as a function of fluid properties and wellhead choke characteristics. For this reason, a comprehensive databank was adopted from the petroleum industry, and then, the databank was split into three groups of training set for model construction (70% of database), test set for model evaluation (15% of database), and validation set for avoiding over‐fitting problem (15% of database). For assessing of GEP model, numerous statistical and graphical tools were applied, and then, it was compared with widely applied literature correlations. Consequently, the proposed tool in this study gives the best fit with the actual flow rate data with the average absolute relative deviation of 11.0872% and determination coefficient (R2) of 0.9695. Additionally, cumulative frequency plot demonstrates that the GEP model has the highest frequency over the database. The outcomes of the GEP model were also compared with the outputs of the artificial neural network (ANN) revealing the higher precision of the ANN than the proposed GEP model in this study. At the end, it is worthwhile that the suggested model can be used as reliable tool for choke performance modeling. © 2017 Curtin University and John Wiley & Sons, Ltd.

Modeling of biodiesel production in Liquid-Liquid Film Reactors including mass transfer effects

Biodiesel production in Liquid-Liquid Film Reactors (LLFR) has been investigated to increase mass transfer without dispersion between the oil and alcohol phases. The use of this type of reactor reduces separation time and increases process productivity. In this work, a model to predict continuous production of biodiesel in a co-current operated LLFR was developed and experimentally validated. This model includes the prediction of the methanol mass transfer from the alcohol phase to the interface. Experimental validation also assessed the effect of the packing surface area to reaction volume ratio (444 to 5333m−1), vegetable oil (VO) flow rate (5 to 40g min−1), and reactor length (0.25 to 1m) on conversion and yield to fatty acid methyl esters (FAME), at constant temperature (55°C), catalyst concentration (1wt%) and molar ratio methanol to oil (6:1). The mathematical model accurately describes the reactor behavior. Conversion, yield and reactor productivity increase with packing quantity and VO flow rate. The highest conversion and yield obtained experimentally were 99.9% and 97.5% respectively with a productivity of 2.5m3 Biodiesel m−3h−1. This value resulted 8 times higher than the typical BSTR operation.

Energy efficiency optimization in scheduling crude oil operations of refinery based on linear programming

For sustainable development, a refinery is required to save energy as much as possible so as to reduce the emission of greenhouse gas. In crude oil operations, oil transportation from storage tanks to charging tanks via a pipeline consumes a large portion of energy. It is vitally important to minimize energy consumption for this process. Since the oil flow resistance is proportional to the square of oil flow rate, the relation between energy efficiency and flow rate is nonlinear, which makes the problem complicated. This work addresses this important issue by formulating a linear programming model for the considered problem such that it can be efficiently solved. A real-world industrial case study is used to demonstrate the applications and significance of the proposed method.