Increase In Oil Viscosity Research Articles

Mechanism simulation of oil displacement by imbibition in fractured reservoirs

Abstract The mechanism model of both static and dynamic imbibition considering capillary pressure and gravity was presented based on the imbibition mechanisms and seepage theory. The validation of the model was performed using published experiment data. Then, this model was employed to study the impacts of oil viscosity, matrix permeability, core size, interface tension, and displacement rate on imbibitions. The results show that, the recovery decreases as oil viscosity increases, and the initial imbibition rate is much faster for lower viscosity oil. Imbibitions recovery is positively related to matrix permeability, the differences of oil recovery for low-permeability to tight oil reservoirs are obvious. Imbibitions effect is negatively related to core size. If the interface tension is low, imbibitions cannot occur without consideration of gravity. But it can occur even in very low interface tension scenario with consideration of gravity. On the whole, the recovery first increases and then decreases as the interface tension decreases. The gravity and capillary play different roles at different ranges of interface tension. There exists an optimal value range of displacement rate in fractured reservoir, which should be optimized with a sufficient oil production rate to achieve higher recovery.

Droplets banding characteristics of water-in-oil emulsion under ultrasonic standing waves

Droplets banding is critical to emulsion separation under ultrasonic irradiation as it can greatly improve the separation efficiency. In this paper, the formation process of droplets banding under ultrasonic standing waves was precisely captured by high-speed microscopic photography; by processing the images, the droplets banding characteristics, including the banding formation time and banding interval, were extracted. Then the effects of acoustic intensity, frequency, droplet size, and physical properties of oil and water on the droplets banding characteristics were discussed in details. The results show that the range of acoustic intensities, within which the droplets banding can form, increases with the increase of the frequency; a maximum allowable acoustic intensity exists for banding formation, which also increases with the frequency. The banding formation time, which increases with increasing oil viscosity but decreases with droplet size, is found to be hardly affected by the oil-water interfacial tension. In addition, the banding interval is only related to the frequency, which closely corresponds to the half wavelength.

Investigation of oil-water flow regimes and pressure drops in mini-channels

Oil-water flow regimes were studied in 2.1 mm and 3.7 mm borosilicate glass tubes; both tubes exhibit Eötvös numbers less than one and therefore surface tension forces may be more important in these mini-channels compared to larger diameter tubes. A closed-loop, adiabatic experimental apparatus was constructed and validated using water. This study focused on tap water and two mineral oils (i.e., Parol 70 and 100) with a density of 840 kg/m3 but a factor of two difference in viscosity. Experiments included a wide range of oil superficial velocities (e.g., 0.84–6.84 m/s for D = 2.1 mm and 0.27–3.30 m/s for D = 3.7 mm) and water superficial velocities (e.g., 0.21–7.69 m/s for D = 2.1 mm and 0.07–4.96 m/s for D = 3.7 mm). Stratified, annular, intermittent, and dispersed flow regimes were observed in both tubes, although the annular flow regime was more prevalent in the smaller tube. Pressure drops increased with decreasing tube diameter and were flow regime dependent. Flow maps were created for these mini-channels and equations adapted from Brauner and Maron (1999) were used to predict the flow regime transitions. The effects of viscosity were modest, although increased oil viscosity enhanced stability of oil-water flows.

Effect of oil viscosity on oil migration in a two-phase model system (cream-filled chocolate)

Using tricaprylin, flaxseed oil, safflower oil, and peanut oil, we investigated the effect of oil viscosity on oil migration in a two-phase model system, to understand oil migration in cream-filled chocolate products. Non-tempered cocoa butter was used as the matrix, while interesterified hydrogenated palm oil mixed with each of the oils (60:40 w/w) was used as the cream phase. Oil migration was monitored using a flatbed scanner. Results of our study showed that tricaprylin, which had the lowest viscosity of about 37.2 mPa·s at 18 °C, exhibited the highest oil migration rate and diffusion coefficient; while flaxseed oil, safflower oil, and peanut oil with viscosities of about 60, 73.6, and 97.2 mPa·s at 18 °C, respectively, showed low oil migration rates and diffusion coefficients. These findings support the fact that as oil viscosity increases, oil migration rate decreases. Furthermore, a critical viscosity of above 60 mPa·s was found to significantly decrease oil migration rate, and therefore extend the shelf life of cream-filled chocolate products. The current study provides an experimental evidence and practical information to confirm existing knowledge, which is valuable for the understanding of oil migration in cream-filled chocolate products.

Slug frequency in high viscosity oil-gas two-phase flow: Experiment and prediction

The number of slug units that traverses a particular point at a given time within a defined pipe cross-section is known as slug frequency. The behaviour of this critical parameter for two-phase flow in high viscosity oils is significantly different from those of conventional oils (of less than 1Pas). In this experimental investigation, new data on slugging frequency in high viscosity oil-gas flow are reported. Scaled experiments were carried out using a mixture of air and mineral oil in a 17m long horizontal pipe of 0.0762m ID. A high-speed Gamma Densitometer of frequency of 250Hz was used for data acquisition over a time interval of 30s. For the range of flow conditions investigated, increase in oil viscosity was observed to strongly influence the slug frequency. Comparison of the present data with prediction models available in the literature revealed discrepancies. A new correlation incorporating the effect of viscosity on slug frequency has been proposed for horizontal flow. The proposed correlation will improve the prediction of slug frequency in high viscosity oils.

The effect of ageing on elastohydrodynamic friction in heavy-duty diesel engine oils

To further improve the efficiency of machine components found in automotive engine systems it is important to understand the friction generation in these components. Modelling and simulation of these components are crucial parts of the development process. Accurate simulation of the friction generated in these machine components is, amongst other things, dependent on realistic lubricant rheology and lubricant properties, where especially the latter may change during ageing of the lubricant. Many modern heavy-duty diesel engines are in operation for several hundred hours before the engine oil is changed. In this work, two engine oils, one 10 W-30 and one 5 W-20, have been aged in full heavy-duty diesel engine bench tests for 400 and 470 hours respectively. This roughly corresponds to the amount of ageing these oils are subjected to between oil drains in field conditions. The aged oils were subjected to a number of oil analyses showing, among other things, a maximum increase in oil viscosity of 12.9% for the 5 W-20 oil and 5.5% for the 10 W-30 oil, which is most likely primarily an effect of evaporation and oxidation. The aged oils were tested in a ball-on-disc test rig under elastohydrodynamic conditions where friction was measured and the performance was compared to fresh samples of the same oils. The results show that there is almost no difference in elastohydrodynamic friction when comparing the aged oils with the fresh oils. These results indicate that it is not necessary to include oil ageing in numerical elastohydrodynamic friction models as long as the oil is changed before the ageing has reached a critical level.

Effect of Viscosity on Oil Production by Cocurrent and Countercurrent Imbibition From Cores With Two Ends Open

Summary Spontaneous imbibition is an important mechanism of oil recovery in naturally fractured reservoirs. The flow of oil from matrix system to fracture system will generally involve both cocurrent and countercurrent imbibition. Understanding the mechanism of cocurrent and countercurrent imbibition is essential in oil recovery from fractured reservoirs. In the previous work, we focused on the purely cocurrent imbibition (Meng et al. 2015), and we now focus on the combination of cocurrent and countercurrent imbibition. In this paper, a new mathematical model, which could be used to simulate the combination of cocurrent and countercurrent imbibition with the two-ends-open oil/water (TEO-OW) boundary condition, is developed. In the TEO-OW boundary condition, one end face of the core is exposed to water and the other is exposed to oil. Experiments of spontaneous imbibition with the TEO-OW boundary condition were performed. Air and oil were used as the nonwetting phase in the experiments to obtain different viscosities ranging from 0.018 to 103.4 cp. The porous media used in the experiments were packed with glass beads or quartz sand, both of which were strongly water-wet. The geometry of the glass beads is spherical and the particle-size distribution is narrow, and the geometry of the quartz sand is irregular and the particle-size distribution is wide. Both oil production from inlet and outlet faces and the advancing distance of the imbibition front were measured against time. The experimental results showed that the largest fraction of the oil/gas production occurred by cocurrent imbibition in both glass-bead packs and quartz sandpacks. In addition, for glass-bead packs, very little of the oil/gas was produced by countercurrent imbibition, and it has almost no change with the increase in oil/gas viscosity. For quartz sandpacks, much more oil/gas was produced by countercurrent imbibition, and it increases noticeably with the increase in oil/gas viscosity (but is still much smaller than cocurrent imbibition). The total oil/gas recovery for glass-bead packs is high and has almost no change with the increase in oil/gas viscosity. In contrast, the total oil/gas recovery for quartz sandpacks is lower and decreases noticeably with the increase in oil/gas viscosity. The relative permeability to water and oil could be obtained by fitting the simulated results with the experimental results. The fitting results show that the relative permeability to water behind the imbibition front decreases with the increase in oil viscosity and the relative permeability to oil for countercurrent imbibition increases with the increase in oil viscosity.

Mechanism and sensitivity analysis of an inflow control devices (ICDs) for reducing water production in heterogeneous oil reservoir with bottom water

The improved oil recovery (IOR) mechanism of ICDs is usually contributed to equalizing pressure drop to achieve an evenly distributed inflow profile along the horizontal section. Substantially, in heterogeneous oil reservoirs with bottom water, the intrinsic mechanism is changing the pressure distribution in formation to effectively utilize the energy of bottom water. In this work, a reservoir-ICD-wellbore coupled model was established and the corresponding simulator was developed. In the rest of the paper, this model was used to discover the mechanisms of ICDs in heterogeneous reservoir with bottom water. Finally, the sensitivity of many factors on oil recovery factor and IOR of ICDs were demonstrated. The results show that ICDs can improve the recovery and delay the water coning. The intrinsic mechanisms of ICDs contains both equalizing pressure drop around the wellbore and changing the direction of lateral flow to increase the sweep volume of bottom water, but ICDs is essentially a shallow profile control technique. The IOR of ICDs is significant in strong heterogeneous oil reservoirs; the IOR increases as the well production rate and oil viscosity increase; as Kv/Kh (the ratio of vertical to horizontal permeability) and HD (dimensionless water avoidance height) increase, the IOR first increases and then decreases, the optimal values are related to the permeability heterogeneity.

Oil absorbency of diatomite-embedded polypropylene meltblown composite structures

In this study, optimized conditions were established for diatomite grinding, which is a natural inorganic mineral with inherently high oil absorption capacity. Diatomite surface was modified with a fluorocarbon chemical and stearic acid via facile methods for enhancing compatibility between polypropylene and diatomite. Polypropylene/diatomite composites were generated in a twin screw extruder with/without using compatibilizer, and nonwoven structures were produced via meltblown technique. Pore size and void content analyses showed that addition of diatomite led to thicker fibers (1–17 µm (the neat polypropylene) vs. 1–32 µm (2 wt.% diatomite containing polypropylene)). Diatomite incorporation into polypropylene resulted in a rigid and brittle structure and a worsened oil absorption property (rust inhibitor oil absorption capacity: 1184% ± 105% (the neat polypropylene) vs. 718% ± 78% and 1089% ± 136% (2 wt.% diatomite containing polypropylene)). Increasing oil viscosity resulted in increased discrepancy among the oil absorption capacities of the neat polypropylene and diatomite containing polypropylene. Analysis of variance tests showed no changes or statistically insignificant differences in oil absorbency.

Quantitative Characterization of Dynamic Heterogeneity in Reservoirs With Stratified Noncommunicating Layers

Due to the difference of permeability in reservoir and viscosities between oil and water, oil displacement efficiencies at different locations differ significantly. Also, along with the water flooding process, the differences of oil displacement efficiencies change in time and manifest dynamic characteristics, which is called dynamic heterogeneity in this paper. A new parameter called “conductivity index” (IC) is defined, and the Gini coefficient of IC (GCIC) is selected to quantitatively characterize the dynamic heterogeneity in reservoirs with stratified noncommunicating layers. Then, the changing laws and influential factors of GCIC are investigated by physical experiments and numerical simulation methods. Finally, the application of dynamic heterogeneity in individual-layer water injection technique is studied. Based on the theory of seepage flow mechanics, the formula of IC is derived. IC not only contains static parameters including permeability, water, and oil viscosity but also contains dynamic parameters including water and oil relative permeabilities, which are both function of water saturation and also function of rock type. Therefore, IC can reflect the dynamic heterogeneity caused by water flooding process. A five parallel sandpacks' water flooding experiment is conducted to investigate the changes of dynamic heterogeneity. Results show that the value of GCIC increases rapidly before the water breakthrough of the sandpack with highest permeability. Then, after water breakthrough, GCIC decreases slowly. A new parameter GCI is defined to represent the average increase of GCIC during the water flooding process. By numerical simulation method, the influences of Gini coefficient of permeability (GCP) and oil viscosity on GCI are studied. Results show that GCI increases along with the increase of oil viscosity. And GCI first increases and then decreases along with the increase of GCP. When GCP equals 0.6, GCI gets its maximum value. Taking block P of Shengli Oilfield in China, for example, the changes of dynamic heterogeneity along the water flooding process are studied. Results show that the dynamic heterogeneity of each well group varies greatly before and after water flooding. For some well groups, the relative sizes of GCIC even reverse. The performances of different cases in individual-layer water injection technique are investigated by numerical simulation method. Results show that the case both considering dynamic heterogeneity and the remaining oil volume gets the best performance.

Analysis of Aged Oil on the Cooling of Power Transformers from Computational Fluid Dynamics and Experimental Measurements

In this paper, experimental and numerical investigations were conducted to study the aging impact on the cooling capacity of mineral oils in power transformers. The experimental investigations had three objectives. Firstly the study of the impact of oil aging on its physicochemical properties using two diagnostic techniques which are: DDP (Dissolved Decay Products) according to ASTM (American Society for Testing and Materials)-D6802 standard and Interfacial Tension (IFT) according to ASTM-D971 standard. Secondly,the study of the impact of oil aging on its viscosity according to ASTM D445. Finally the development of empirical equations depicting oil viscosity changes, to be implemented in the numerical model. To achieve this, accelerated thermal aging tests of mineral oil samples were conducted in laboratory conditions according to ASTM D-1934standard. Data from experimental investigations were used to conduct the numerical investigations. A 2D axisymmetric numerical model was developed with COMSOL Multiphysics 4.3a to study the cooling capability of oil aged at different levels. The results indicate that the oil physicochemical properties are affected by aging. Furthermore the results show that the oil viscosity increase with aging and give a good correlation between viscosity and aging indicators. Finally it was found that sludge from oil oxidation byproduct contributes to the formation of hotspots and this leads to a significant increase of hotspot temperature in the power transformers.

Influence of oil type on formation, structure, thermal, and physical properties of monoglyceride‐based organogel

This research studied the possible relation between oil properties and structure and physical properties of saturated monoglyceride (MG)‐based organogels. To this aim different oils (castor, cod liver, corn, extra virgin olive, flax‐seed, peanut and sunflower oil, and mixture of medium chain triacylglycerols (MCT)) were used to prepare organogels by adding 10% w/w of monoglycerides. The fatty acid composition, viscosity, and dielectric properties of oils were measured. Then, organogels were characterized for crystallization induction time, dielectric properties, firmness, rheological behavior, thermal properties, crystal morphology by polarized light microscopy, and crystal polymorphism by synchrotron X‐ray diffraction (XRD) analysis.Results acquired showed that the addition of MG in different types of oils led to the formation of organogels with different properties. In all cases, β polymorph formed in the system irrespective of oil type. Regarding oils containing long chain fatty acids, gel firmness, and other structural parameters correlated well with the dielectric constant and/or viscosity of oils: increasing oil viscosity or decreasing oil dielectric constant, firmness and rheological parameters linearly increased. On the other hand, these correlations cannot be found including in the statistical analysis castor oil or MCT, probably due to the higher ability of these oils to make dipole–dipole rotation as well as the higher solubility of MG in castor oil.Practical applications: Oil gelation (organogelation) is a relative novel strategy to convert liquid oils into structured systems that has attracted food scientists and industry managers looking for solutions to reduce saturated/trans fats, deliver bioactive molecules, and minimize oil migration in foods. Results acquired in this research highlight that the choice of oil to be structured by means of saturated monoglycerides could affect the final gel structure. These findings could be useful in the attempt to applied organogels in different food products having different physical properties.This research studies the effect of oil properties on structure and physical properties of saturated monoglyceride‐based organogels. Results show that only the dielectric constant and/or viscosity of long chain fatty acid oils correlated well with gel firmness and other structural parameters.

Characteristics and densification mechanisms of shallow oil in Chengbei Terrace Area

ABSTRACTShallow oil is gaining more and more attentions worldwide due to its low cost. However, it is easy to form heavy oil in shallow layers. The wide varieties of oil make research on this subject difficult and oil densification mechanisms are usually controversial. Therefore, the geochemical characteristics of both heavy and light oil in shallow layers are compared and studied comprehensively. Research is conducted on the physical properties, group compositions, and diverse biomarkers. Most shallow oil samples exhibit high densities and low freezing points, which show low-sulfur biodegradation environment. With respect to group compositions, asphalts are more prevalent in the sag center. At different oil densification stages, tricyclic and tetracyclic terpanes are found to increase when viscosity is more than 1000 cp, and decrease when viscosity is less than 1000 cp. Pr/nC17 has similar characteristics. The changes in the contents of n-alkanes and tricyclic terpanes are found to be diametrically opposed when the oil viscosity increases. Underground water and fault systems are found to be the most important factors of oil densification in shallow oil reservoirs. The research on the geochemical characteristics of shallow oil is important to find better development methods and to select high-quality oil.

Low temperature air injection with solvents in heavy-oil containing naturally fractured reservoirs: Effects of matrix/fracture properties and temperature on recovery

Implementation of in situ combustion process in fractured reservoirs might be risky due to quick breakthrough of unconsumed oxygen to the producers. Recently, we proposed low temperature air–solvent injection (LTASI) as an alternative process to overcome this problem (SPE 149896 and 174542). This process involved oxygen addition reactions (low temperature oxidation) rather than bond scission reactions (in situ combustion). Because increase in matrix oil viscosity is the drawback associated with oxygen addition reactions, reduction of it by adding hydrocarbon solvent into the air injected can be a solution. Determination of optimal application conditions of this kind of expensive and risky process is critically important.Based on promising results reported in SPE 174542, we conducted new static experiments of air and hydrocarbon solvent injection at low temperature oxidation conditions that complement previous lab studies. Vertically situated sandstone and limestone samples were exposed to air+propane (or butane) mixture under static conditions mimicking huff-and-puff (cyclic injection) type injection. The main purpose was to determine the effect of change in matrix size as well as different matrix/fracture volume ratios on matrix oil recovery. This is important because this method is proposed as a cyclic injection application and the cyclic times are determined by the volume of the fractures, which are to be filled with injected air/propane and the diffusion rate of these gases into matrix.During the experiments, the gas was injected in the annular space representing a fracture surrounding a heavy oil saturated core at certain pressure and temperature for a certain (soaking) time period. The produced gas and liquid oil were tested in different cycles using a gas chromatograph. The effect of fracture volume, matrix size, and application temperature on the produced fluid composition was studied.An extensive experimental schedule for static diffusion experiments was accomplished in which the effect of some variables in the oil recovery and oxygen consumption was analyzed. The variables evaluated include rock type (sandstone, limestone), temperature (75, 150, 200°C), fracture volume, solvent type (C3, C4), matrix size (2-in. diameter, 6-in. length; 3.2-in. diameter, 9-in. length), and injection sequences (Air/C3/Air, C3/Air/C3, etc.). A total of 21 experiments were carried out for a comparative analysis and optimal application conditions yielding increased oil recovery and increased oxygen consumption through oxidation reactions in the matrix were determined. These optimal conditions will provide reduced risk due to early breakthrough of unconsumed oxygen and maximized profit, which is needed due to the high cost of propane.

ON STABILITY OF THE OIL DISPLACEMENT FRONT UNDER CONDITIONS OF THERMOGAS IMPACT ON THE OIL BEARING LAYER

The method of thermogas impact on the oil bearing layer is a perspective one to improve oil recovery. It is now under experimental implementation in Belarus. Stability of the thermal front and that of the oil displacement is a point of principle for the given technology. The article offers solution based on the method of small perturbations for the problem of the oil-displacement front stability under thermogas impact on the oil layer. The perturbation growth increment is shown to be quite different from that of the gas filtration combustion. Being determined by the perturbation wave number (or wave length), by difference in speed of the blowing filtration and that of the heat development front, by the ratios of densities, filtration coefficients, compressibility of the displacement agent and the displaced oil mass, and by other parameters. The author analyses the main parameters influencing the stability of the front. Recommendations are given on possible methods and procedures improving stability of the displacement front (neutralizing perturbation growth). The mechanisms of suppression or compensation of the front perturbation growth are as follows: the crude oil viscosity reduction and increase of that of the displacement agent, the displacement agent compressibility increase, increase of the thermogas impact heat-front width in the first instance at the expense of the temperature growth and alteration in the chemism (low temperature catalysts utilization, etc.), reduction in speed of the front propagation and/or correspondingly of the displacement agent feed. Utilization of the gas or water-gas displacement agent as well as the agent impregnation with hydrophobic gases provides a relatively better stability of the front as compared to that employing water based compounds. Analytical data and derived recommendations are offered for utilization within the framework of general techniques and procedures of the thermogas impact process management in the context of developmental and experimental-industrial oil extraction. Further research into methods and mechanisms of the displacement front perturbation compensation, including the front dynamics at nonlinear stage, might be conducted via detailed 2D and 3D numerical simulation of the system.

Variation of Crude Oil Physical Properties and Oil Recovery of Natural Gas Flood Under Different Pressures

ABSTRACTFor the gas flood process, crude oil physical properties including oil volume and viscosity would be greatly changed resulting from gas solution and extraction. First, solubility of natural gas in oil and brine was measured and compared. Meanwhile, the resulting oil expansion and viscosity reduction were experimentally tested. Second, oil viscosity increase due to extraction was studied by extraction experiments. Finally, oil recovery of natural gas and propane-enriched natural gas flood was studied under different pressures. Results show that solubility of natural gas in oil is dozens of times of that in brine. Variation of crude oil physical properties during natural gas injection mainly includes the remarkable volume expansion and viscosity reduction caused by gas dissolution into oil, and the oil volume shrinkage and viscosity increase caused by extraction are not so significant. The oil recovery of natural gas flood grows linearly with increased injection pressure and gas solubility in oil, but is still less than 90% even at 55 MPa, which indicates immiscible flood at 55 MPa. Addition of propane to natural gas is proved to be helpful for enhancing oil recovery and achieving miscibility.

Numerical approach for enhanced oil recovery with surfactant flooding

The remained oil in the reservoir after conventional water-flooding processes, forms a dispersed phase in the form of oil drops which is trapped by capillary forces and is almost about 70% of the original oil in the place (OOIP). To reduce oil residual saturation in laboratory experiments and field projects, surfactant flooding is effective via decreasing the interfacial tension mobility ratio between oil and water phases. Estimation of the role of design variables, like chemical concentrations, partition coefficient and injection rate in different performance quantities, considering a heterogeneous and multiphase oil reservoir is a critical stage for optimal design. Increasing demand for oil production from water-flooded reservoirs has caused an increasing interest in surfactant-polymer (SP) and alkali-surfactant-polymer (ASP). Modeling minimizes the risk of high cost of chemicals by improving our insight of process. In the present paper, a surfactant compositional flood model for a three-component (water, petroleum and surfactant), two phase (aqueous and oleic) system is studied. A homogeneous, two-dimensional, isothermal reservoir with no free gas or alkali is assumed. The governing equations are in three categories: the continuity equations for the transport of each component, Darcy's equation for the transport of each phase and other auxiliary equations. The equations are solved by finite-differences using a procedure implicit in pressure and explicit in saturation. The validation of the model is achieved through comparing the modeling results with CMG simulators and Buckley–Leverett theory. The results of modeling showed good agreement with CMG results, and the comparison with Buckley–Leverett theory is explained according to different assumptions. After validation of the model, in order to investigate sensitivity analysis, the effects of system variables (partition coefficient, surface tension, oil viscosity and surface injection concentration) and performance variable (cumulative oil recovery) are studied. Finally, the comparison of oil recovery between water-flooding and surfactant-flooding was done. The results showed higher oil recovery with changes in capillary number when the partition coefficient is greater than unity. Increasing oil viscosity resulted in decreasing the oil recovery by changing in fractional flow. Moreover, it was concluded that the oil recovery was enhanced by increasing surfactant injection concentration. The oil recovery was increased when surfactant was injected to the system and this result was obtained by comparing water-flooding and surfactant-flooding.

Delayed Operation Characteristics of Power Shuttle According to Hydraulic Oil Temperature in the Hydraulic Circuit of Agricultural Tractor

Purpose: During the start-up period, the response time of a hydraulic system increases in the winter because of the increased oil viscosity caused by the cold weather. The problems of delayed tractor starting and excessive wear of the clutch disk occur for these reasons. Therefore, this study develops an analysis model using the commercial hydraulic analysis program AMESim to examine the characteristics of delays in power shuttle starting at different oil temperatures. Methods: In the experiment, a tractor was stationary on a flat surface with the engine running at a constant speed of 1,080 rpm. The forward lever was then pressed to activate the power shuttle at three different oil temperatures, and the pressure changes were measured. The pressure on the forward clutch control valve was measured by a pressure gauge installed on the hydraulic line supplied to the transmission from the main valve. An analysis model was also developed and verified with actual tests. Results: The trend of the simulated pressures of the power shuttle is similar to that of the measured pressures, and a constant modulation period was observed in both the simulation and test results. However, the difference found between the simulation and test results was the initial pressure required to overcome the initial force of the clutch spring. Conclusions: This study also examines the characteristics of the delayed startup of the power shuttle at different oil temperatures through simulations.

Effect of dodecyl benzene sulfonic acid (DBSA) and lauric amine (LA) on the associating state and rheology of heavy oils

Abstract The effects of two amphiphiles, DBSA and LA, on the associating state and viscosity of three heavy oils with different resin/asphaltene (R/A) mass ratios were investigated through DSC analysis, rheological test and electrical conductivity measurement. The wax appearance temperatures of the three heavy oils are lower than 40 °C. The viscosity of heavy oils at temperature range 50~70 °C increases with increasing DBSA concentration but decreases with increasing LA concentration. Addition of DBSA increases the electrical conductivity of heavy oils, which implies that the DBSA acts as asphaltene dispersants; the electrical conductivity of heavy oils decreases after LA addition, which implies that the LA acts as asphaltene flocculants. The addition of DBSA decreases the size of asphaltene particles and generates new solvation layers, both of which favor the increase of heavy oil viscosity; the addition of LA increases the size of asphaltene particles and releases some liquid oils bounded by asphaltene particles, both of which favor the decrease of heavy oil viscosity. With the increase of R/A mass ratio, the stability of heavy oils increases while the viscosity enhancing/reducing efficiency of DBSA/LA decreases.

Validation of a new phenomenological “jump-and-channel” model for the wet pressure drop of oil mist filters

The “wet pressure drop” of oil mist filters (i.e. the increase in differential pressure of the air flow due to loading of the filter with liquid) is presented as a function of two mechanisms by which coalesced oil is transported through the filter. These mechanisms operate in separate regions of the filter and make separate (and separately measurable) contributions to the overall wet pressure drop. This new concept, which was first formulated qualitatively in a phenomenological model by Kampa et al. (2014), leads to semi-quantitative predictions regarding the dependence of pressure drop Δp and saturation S on filter operating conditions, filter properties and liquid properties. These predictions are first formulated and then validated for a range of wettable and non-wettable filter media in combination with 4 mineral oils of different viscosity. The key findings, summarized below, are consistent with the model and apply to both wettable and non-wettable media.Oil transport across media interfaces (i.e. transitions between regions of different porosity and/or wettability) was associated with a relatively sharp increase in pressure drop ∆p and oil saturation S over a very thin layer of the filter (a “∆p jump”). The magnitude of this ∆p jump was determined by the media properties. It correlated well with the respective static break-through pressures for oil or air, but did not depend on the oil viscosity and loading rate of the filter (at constant air velocity). Oil transport through channel regions of the filter (i.e. the regions connecting interfaces) was associated with a linear increase in ∆p with channel length and liquid throughput. The corresponding saturation level S was relatively flat throughout the channel region and lower than at an interface. (Both quantities are media dependent, of course.) An increase in oil viscosity μ (at constant oil throughput) led to different responses depending on filter wettability.