Oil Thickness Research Articles

Laboratory measurements of high-frequency broadband acoustic backscatter from sea ice, oil under sea ice, and oil encapsulated in sea ice

To investigate the potential for detection of crude oil under sea ice using active acoustics techniques, measurements of high-frequency broadband backscattering (75–590 kHz) from crude oil of different thicknesses (0.7–8 cm) under, and frozen within, laboratory sea ice have been performed at the Cold Regions Research and Environmental Laboratory (Hannover, NH). Backscattering measurements were performed at normal and 20 degrees from normal incidence. The data have been analyzed in both the temporal domain and in the frequency domain, allowing scattered spectra from the oil and ice to be measured. The results show structure consistent with scattering from multiple interfaces following the injection of oil under the ice and during the subsequent encapsulation the oil layer. The acoustic estimates of oil thickness are in general agreement with ancillary measurements. The sound speed of the crude oil was separately measured over a range of relevant temperatures, both to inform a scattering model and to accurately infer the oil thickness. Predictions based on a simple scattering model for the frequency-dependent reflection coefficient of oil under ice agree well with the normal incidence measurements prior to oil encapsulation. At angles off normal incidence, volume inhomogeneities appear to dominate the scattering.

ESTIMATION OF THE THICKNESS AND EMULSION RATE OF OIL SPILLED AT SEA USING HYPERSPECTRAL REMOTE SENSING IMAGERY IN THE SWIR DOMAIN

Abstract. The thickness and the emulsion rate of an oil spill are two key parameters allowing to design a tailored response to an oil discharge. If estimated on per pixel basis at a high spatial resolution, the estimation of the oil thickness allows the volume of pollutant to be estimated, and that volume is needed in order to evaluate the magnitude of the pollution, and to determine the most adapted recovering means to use. The estimation of the spatial distribution of the thicknesses also allows the guidance of the recovering means at sea. The emulsion rate can guide the strategy to adopt in order to deal with an offshore oil spill: efficiency of dispersants is for example not identical on a pure oil or on an emulsion. Moreover, the thickness and emulsion rate allow the amount of the oil that has been discharged to be estimated. It appears that the shape of the reflectance spectrum of oil in the SWIR range (1000–2500nm) varies according to the emulsion rate and to the layer thickness. That shape still varies when the oil layer reaches a few millimetres, which is not the case in the visible range (400–700nm), where the spectral variation saturates around 200 μm (the upper limit of the Bonn agreement oil appearance code). In that context, hyperspectral imagery in the SWIR range shows a high potential to describe and characterize oil spills. Previous methods which intend to estimate those two parameters are based on the use of a spectral library. In that paper, we will present a method based on the inversion of a simple radiative transfer model in the oil layer. We will show that the proposed method is robust against another parameter that affects the reflectance spectrum: the size of water droplets in the emulsion. The method shows relevant results using measurements made in laboratory, equivalent to the ones obtained using methods based on the use of a spectral library. The method has the advantage to release the need of a spectral library, and to provide maps of thickness and emulsion rate values per pixel. The maps obtained are not composed of regions of thickness ranges, such as the ones obtained using discretized levels of measurements in the spectral library, or maps made from visual observations following the Bonn agreement oil appearance code.

Thin-Film Growth Rate Monitor by Normal-Incidence Reflectance

An in situ technique for monitoring the growth rate and optical constants of the thin semiconductor layer by the normal-incidence reflectance is proposed. To demonstrate the feasibility of the proposed method, the variation of the air gap between two glasses is used to simulate growth system. We also used the spin coater to thin the thickness of the salad oil to test the performance of the measurement system. The experiments indicate that we can determine the thickness variation and optical constants of the test sample in real time.

Development of waterborne oil spill sensor based on printed ITO nanocrystals

Oil spill accidents occasionally occur in coastal and ocean environments, and cause critical environmental damage, spoiling the marine habitats and ecosystems. To mitigate the damages, the species and amount of spilled oil should be monitored. In this study, we developed a waterborne oil spill sensor using a printed ITO layer. ITO is a compatible material for salty environments such as oceans because ITO is strong against corrosion. The fabricated sensor was tested using three oils, gasoline, lubricant and diesel, and different oil thicknesses of 0, 5, 10, and 15mm. The results showed that the resistance of the sensor clearly increased with the oil thickness and its electrical resistance. For sustainable sensing applications in marine environments, XRD patterns confirmed that the crystal structure of the ITO sensor did not change and FE-SEM images showed that the surface was clearly maintained after tests.

Analysis of thermoelastohydrodynamic performance of journal misaligned engine main bearings

To understand the engine main bearings’ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely considered simultaneously in most studies. A typical finite element model is selected and the effect of thermoelastohydrodynamic(TEHD) reaction on engine main bearings is investigated. The calculated method of main bearing’s thermal hydrodynamic reaction and journal misalignment effect is finite difference method, and its deformation reaction is calculated by using finite element method. The oil film pressure is solved numerically with Reynolds boundary conditions when various bearing characteristics are calculated. The whole model considers a temperature-pressure-viscosity relationship for the lubricant, surface roughness effect, and also an angular misalignment between the journal and the bearing. Numerical simulations of operation of a typical I6 diesel engine main bearing is conducted and importance of several contributing factors in mixed lubrication is discussed. The performance characteristics of journal misaligned main bearings under elastohydrodynamic(EHD) and TEHD loads of an I6 diesel engine are received, and then the journal center orbit movement, minimum oil film thickness and maximum oil film pressure of main bearings are estimated over a wide range of engine operation. The model is verified through the comparison with other present models. The TEHD performance of engine main bearings with various effects under the influences of journal misalignment is revealed, this is helpful to understand EHD and TEHD effect of misaligned engine main bearings.

Experimental study of liquid-immersion III–V multi-junction solar cells with dimethyl silicon oil under high concentrations

In order to better apply direct liquid-immersion cooling (LIC) method in temperature control of solar cells in high concentrating photovoltaic (CPV) systems, electrical characteristics of GaInP/GaInAs/Ge triple-junction solar cells immersed in dimethyl silicon oil of 1.0–30.0mm thickness were studied experimentally under 500 suns and 25°C. Theoretical photocurrent losses caused by spectrum transmittance decrease from spectral absorption of silicon oil were estimated for three series sub-cells, and an in-depth analysis of the electrical performances changes of the operated cell in silicon oil was performed. Compared with cell performances without liquid-immersion, the conversion efficiency and the maximum output power of the immersed solar cell in silicon oil of 1.0mm thickness has increased from 39.567% and 19.556W to 40.572% and 20.083W respectively. However, the cell electrical performances decrease with increasing silicon oil thickness in the range of 1.0–30.0mm, and the efficiency and the maximum output power of the cell have become less than those without liquid-immersion when the silicon oil thickness exceeds 6.3mm.

Film thickness and traction curves of wind turbine gear oils

The film thickness and the traction curves of four fully formulated wind turbine gear oils were measured on a ball-on-disc device. All oils have the same viscosity grade (ISO VG 320) and different formulations: ester, mineral, PAO and mineral+PAMA.Film thickness and traction coefficient results will be presented. The film thickness measurements were compared with predictions using film thickness equations from the literature.

MODELLING OF SEAWATER POLLUTED BY LIGHT AND HEAVY CRUDE OIL DROPLETS

Significant amounts of crude oil transported from offshore fields to the refineries using tankers or pipelines, demand increased control of seawater pollution. Tanker accidents resulting in oil spills drive much attention, as they influence local marine life and coastal industry. However, the most significant annual amount of crude oil enters the sea in the form of oilin-water emulsion as a result of standard tanker operations, offshore oil extraction and daily work of refineries. Many branches of science are challenged to provide new methods for oil detection, less expensive, more sensitive and more accurate. Remote satellite or airborne detection of large oil spills is possible using joint techniques as microwave radars, ultraviolet laser fluorosensors and infrared radars. Some methods are capable to deal with oil streaks detection and estimation of oil thickness. Although there is currently, no method to detect small concentration of oil droplets dispersed in seawater. Oil droplets become additional absorbents and attenuators in water body. They significantly change seawater inherent optical properties, which imply the change of apparent optical properties, detectable using remote sensing techniques. To enable remote optical detection of oil-in-water emulsion, a study of optical properties of two types of crude oil was conducted. Radiative transfer theory was applied to quantify the contribution of oil emulsion to remote sensing reflectance (R rs ). Spectra of R rs from in situ measurements in Baltic Sea were compared to R rs spectra of seawater polluted by 1 ppm of crude oil emulsion, collected using radiative transfer simulation. The light crude oil caused a 9-10% increase of Rrs while the heavy one reduced R rs up to 30% (model accuracy stayed within 5% for considered spectral range). Results are discussed concerning their application to shipboard and offshore oil content detection.

Local surface shear stress measurements from oil streaks thinning rate

This paper presents an approach to evaluate the time-averaged local shear stresses based on the analysis of video images of oil streaks. The time-averaged deformation rate of thin oil streaks, deposited on a model exposed to an air stream, increases pro rata with the skin friction, while it is inversely proportional to the viscosity. Hence, the oil viscosity represents an important parameter in the method to be carefully characterized and selected for the level of aerodynamic skin friction, flow velocity, and time interval to be resolved. Post-processing image techniques were applied to reconstruct the rate of change in the oil thickness from oil streak length monitored by a high-speed camera. The present technique was demonstrated on a model exposed to subsonic and supersonic flows, and results were compared with theoretical calculations. The present measurement procedure offers ancillary information to the conventional qualitative oil dot visualizations, providing the wall shear stresses at a reduced cost and complexity.

3D electrohydrodynamic simulation of electrowetting displays

The fluid dynamic behavior within a pixel of an electrowetting display (EWD) is thoroughly investigated through a 3D simulation. By coupling the electrohydrodynamic (EHD) force deduced from the Maxwell stress tensor with the laminar phase field of the oil–water dual phase, the complete switch processes of an EWD, including the break-up and the electrowetting stages in the switch-on process (with voltage) and the oil spreading in the switch-off process (without voltage), are successfully simulated. By considering the factor of the change in the apparent contact angle at the contact line, the electro–optic performance obtained from the simulation is found to agree well with its corresponding experiment. The proposed model is used to parametrically predict the effect of interfacial (e.g. contact angle of grid) and geometric (e.g. oil thickness and pixel size) properties on the defects of an EWD, such as oil dewetting patterns, oil overflow, and oil non-recovery. With the help of the defect analysis, a highly stable EWD is both experimentally realized and numerically analyzed.

Effects of Ethanol Contamination on Friction and Elastohydrodynamic Film Thickness of Engine Oils

The use of ethanol as engine fuel has increased for environmental reasons, both in flex-fuel engines and as increasing amounts of ethanol blended with gasoline in conventional engines. This article describes an investigation into the effects of ethanol contamination of lubricants during engine use with ethanol fuel. To facilitate this, a new technique was developed to measure small amounts of ethanol in lubricants. Elastohydrodynamic film thickness measurements and Stribeck curves were obtained for Group I base and formulated oils containing small added amounts of ethanol. The effect of the water present in hydrated ethanol was evaluated by carrying out tests using both hydrated and anhydrous ethanol. Measurements were also carried out using a Group II base oil with added ethanol. These measurements showed that in the low entrainment speed region, where the elastohydrodynamic film is very thin so that boundary lubrication prevails, the addition of ethanol produced a boundary film, which was not present for the base oils. By contrast, the addition of ethanol to formulated oil reduced film thickness in all lubrication regimes. The friction tests showed friction reduction due to addition of ethanol to the base oil, in particular at low speeds. For the formulated oil, ethanol reduced friction at high speeds, which was associated with a reduction in the viscosity of the lubricant, but at low speeds, ethanol reduced the formation of a boundary layer, increasing friction. The presence of water in hydrated ethanol did not significantly change the film thickness and friction when compared with anhydrous ethanol.

Elastohydrodynamic Properties of Biobased Heat-Bodied Oils

Heat-bodied oils were prepared by thermal treatment of soybean oil under inert atmosphere. Different viscosity grades of heat-bodied oils synthesized by varying the reaction time were investigated for various properties including viscosity, viscosity index, elastohydrodynamic film thickness, and pressure–viscosity coefficient. Heat-bodied oils displayed elastohydrodynamic film thickness characteristics typical of lubricating oils. The film thickness of heat-bodied oils increased with increasing entrainment speed and viscosity, decreased with increasing temperature, and was unchanged with varying load. Pressure–viscosity coefficients of heat-bodied oils were estimated from film thickness as well as from physical property data. The pressure–viscosity coefficient values of heat-bodied oils increased with increasing viscosity and decreasing temperature and were in the range displayed by such oils as polyol esters, poly-α-olefins, and petroleum-based base oils. Heat-bodied oils provide access to a wide viscosity range of biobased oils not attainable with vegetable oils, without serious negative impact on critical lubricant properties such as viscosity index, film thickness, and pressure–viscosity coefficient.

Experimental and Numerical Studies of Cavitation Effects in a Tapered Land Thrust Bearing

In thrust bearings, cavitation may occur at high rotational speeds or low lubricant supply pressures, and it will influence the bearing performances. In this paper, a hydrodynamic tapered land thrust bearing has been studied both experimentally and numerically, with concentration on the cavitation phenomenon and its effects on the bearing performances. Evident cavitation regions have been observed in the experiments at higher rotational speeds. Traditional Reynolds equation and 3D Navier–Stokes equation (3D NSE) with a cavitation model have been used for numerical simulation, and the predicted results are examined against the experimental results. Compared with Reynolds equation, 3D NSE with Rayleigh–Plesset model provides better predictions of both oil–film pressure profile and cavitation area. Furthermore, the effects of the cavitation phenomenon on the thrust bearing performances are studied by parametric studies involving various rotational speeds and oil feeding pressures, using 3D NSE. It is found that the load capacity decreases at higher speeds because of enlargement of the cavitation area. And the negative effects of cavitation can be reduced at smaller film thickness and higher oil supply pressure. Conclusively, the above results show that the cavitation phenomenon has significant influences on the bearing performances at higher speeds, and 3D NSE provides an effective tool for analyzing the cavitation effects in thrust bearings.

Fish oil disrupts seabird feather microstructure and waterproofing

Seabirds and other aquatic avifauna are highly sensitive to exposure to petroleum oils. A small amount of oil is sufficient to break down the feather barrier that is necessary to prevent water penetration and hypothermia. Far less attention has been paid to potential effects on aquatic birds of so called ‘edible oils’, non-petroleum oils such as vegetable and fish oils. In response to a sardine oil discharge by a vessel off the coast of British Columbia, we conducted an experiment to assess if feather exposure to sheens of sardine oil (ranging from 0.04 to 3μm in thickness) resulted in measurable oil and water uptake and significant feather microstructure disruption. We designed the experiment based on a previous experiment on effects of petroleum oils on seabird feathers. Feathers exposed to the thinnest fish oil sheens (0.04μm) resulted in measurable feather weight gain (from oil and water uptake) and significant feather microstructure disruption. Both feather weight gain and microstructure disruption increased with increasing fish oil thickness. Because of the absence of primary research on effects of edible oils on sea birds, we conducted interviews with wildlife rehabilitation professionals with experience rehabilitating sea birds after edible oil exposure. The consensus from interviews and our experiment indicated that physical contact with fish and other ‘edible oils’ in the marine environment is at least as harmful to seabirds as petroleum oils.

Space charge behavior in the sample with two layers of oil-immersed-paper and oil

Space charge behavior is important in the oil-immersed-paper insulation in converter transformers for HVDC transmission. This paper reports an investigation of the space charge property in samples with two layers of oil-immersed-paper and oil. Based on pulsed electroacoustic (PEA) technique, a waveform recovery method was proposed to get rid of the effects of interface and anisotropy on PEA result, and the space charge distributions in the two-layer samples under different voltage and oil thicknesses were measured. It's found that the charges with the same polarity as oil side electrode were accumulated at the interface and gradually increased with the increase of applied voltage. However, the positive charge charges always appeared in the oil under positive and negative voltages. Moreover, the charges in samples increased with the increase of applied voltage, while the amount of interface charges decreased with the increase of oil thickness. Due to the existence of interfacial charges, the electrical field in oil-immersed-paper was distorted with its maximum close to the interface. It is indicated that due to the different mobility properties of charges in paper and oil and the interface trap state, the interface between paper and oil plays an important role in charge formation and decay.

A study on burning of crude oil in ice cavities

In situ burning is a practical means of oil spill cleanup in icy conditions. This study considers one example of oil spill scenario: burning oil in an ice cavity. A new set of parameters to the classical problem of confined pool fires in vessels arises under these unique conditions. The icy walls of the cavity create a significant heat sink causing considerable lateral heat losses, especially for the small cavity sizes (5–10cm). The melting of ice due to the heat from the flame causes the cavity geometry to change. Specifically, the diameter of the pool fire increases as the burning proceeds. This widening causes the fuel to stretch laterally thereby reducing its thickness at a faster rate. The melted ice water causes the oil layer to rise up, which causes the ullage (the distance from the oil surface to the top surface of ice block) to decrease. The reduction in the ullage and increase in the diameter counter-act the reduction in oil thickness due to the widening. This results in a strong coupling between the mass loss rate and the geometry change of the pool and cavity. To systematically explore this process, experiments were performed in cylindrical ice cavities of varying diameters. It was found that due to the cavity expansion the average mass loss rate of crude oil in the ice cavity is greater than the mass loss rate in a pan. For example, the mass loss rate of crude oil burning in a pan found to be 50% less than that of an ice cavity with similar initial diameter. A model was developed to estimate mass loss rates and efficiencies which are in reasonable agreement with the experimental results. Extension of the model to larger sizes, comparable to realistic situation in the Arctic is discussed.

Analysis of Factors Influencing the Flow Velocity of Heavy Oil Gravity Drive

Based on the assisted gravity draining steam flooding and the development technology of drive drain compound, using computational fluid dynamics software ANYSY CFX to analyze the impact of the reservoir with the angle of inclination and oil reservoir thickness and density of the crude oil on the oil (water) flow velocity. Research shows that: when the density of crude oil is close to the density of water, the speed difference is reduced. When the tilt angle is between 20oand 60o, the flow velocity was significantly reduced. When the reservoir thickness is between 20m and 40m, the growth of seepage velocity is more evident. Research results provide reference for seepage study of gravity drive of heavy oil .

For Response Planning: Predicted Environmental Contamination Resulting from Oil Leakage from Sunken Vessels

An evaluation was made of the amounts and types of oil potentially released from sunken vessels in U.S. waters, where oil would be transported, how rapidly it would reach sensitive resources, and magnitudes of impacts on surface water and shorelines. Oil spill modeling was performed as part of a screening analysis to identify those sunken vessels of highest risk for environmental and socioeconomic impacts, with the expectation that those identified will be subject to more detailed analysis. The modeling provides estimates of the locations of oiling, as well as areas of water surface, lengths of shoreline, and volumes of water exposed above potential effects thresholds (oil thickness or concentrations). We developed regression models of the resulting indices of oil impacts as a function of spill volume, allowing for predictions of water surface area, shoreline extent, and water volume affected for any potential (partial or entire) release volume from the sunken vessel. We ran RPS-ASA's SIMAP model in probabilistic mode, i.e., long-term wind and current records were sampled at random and model runs performed for each of 200 selected spill dates and times. The model results provide a statistical description of the probabilities and potential locations and magnitudes of oil-related impacts. This consequence analysis may be used to assign priorities for potential salvage of sunken vessels based on relative risk. The resultant analysis may be used by decision-makers to evaluate response needs, such as response equipment capacities, timing of deployment required to protect sensitive resources, and possible time windows and areas for dispersant use.

Study on Adaptability of Nitrogen Foam to Control Profile in Offshore Oilfield

Water breakthrough is usually occurred during water flooding process as the high porosity and permeability features of offshore oilfield. The adaptability of nitrogen foam improve profile are evaluated based on laboratory experiment and numerical simulation. The effects of formation rhythmicity, permeability ratio, formation dip, layer thickness and crude oil viscosity on profile control by nitrogen foam are investigated. Study results indicated that nitrogen foam is an efficiency approach to enhance the oil recovery of heterogeneity reservoir by block the water channel and improve the profile. Meanwhile, the application field and appropriate conditions of nitrogen foam are summarized which can be used in the optimization of nitrogen foam in offshore oilfield. Key words : Nitrogen foam; Resistance factor; Numerical simulation; Formation rhythmicity; Permeability ratio

Spreading of oil on water in the surface-tension regime

The third stage of oil spreading on water, in which surface-tension force promotes spreading against the resisting viscous effect, is investigated using a similarity solution in combination with an integral boundary-layer technique to solve the unidirectional oil-spreading dynamics problem in the last stage of spreading. The thin layer is assumed to be supplied by oil from a bulk boundary. Using a constitutive equation for oil-film surface tension versus oil-film thickness, analytical solutions near the bulk boundary and near the edge are developed. Using the asymptotic solutions to initiate integration, the differential equations for the oil thickness, oil velocity, and boundary-layer profiles are integrated starting from the leading edge and bulk boundary, which after matching provide a complete solution. The results for the spreading-law prefactors are found to differ by about 10 % from published theoretical results using the same constitutive equation. Using an empirical constitutive equation for oil-film surface tension versus distance from the bulk boundary leads to a spreading-law prefactor that is in excellent agreement with the published experimental result and published theoretical work providing and using the same empirical constitutive equation.