Effect Of Differential Pressure Research Articles

The Effect of Differential Pressure and Permanent Pressure Loss on Multi-Hole Orifice Plate

Abstract The widely used orifice plate falls under restricted type flow devices, has the highest differential pressure and permanent pressure drop in the ensemble. The objective is to curtail the permanent pressure drop and maintain the differential pressure across the orifice plate, and thereby, the power required to pump the liquid is retrenched. So, three-hole, four-hole and five-hole orifice plates with an identical area to that of the single-hole orifice plate were designed and experiments were carried out. It is observed that the experimental results almost matched with the simulation data. In comparing the performance, the four-hole orifice plate yielded a higher differential pressure and higher-pressure loss. In contrast, the five-hole orifice yielded lower differential pressure and higher-pressure loss compared to the single-hole orifice plate. In case of three-hole orifice plate it performed better than the single-hole orifice with reduced pressure loss and higher differential pressure. It was also found that the power consumed by the pump for pumping was lower for three-hole, four-hole and five-hole orifice plates compared to the single-hole orifice plate. Thus, the three-hole orifice plate performs better than a single-hole orifice plate in terms of higher differential pressure, reduced permanent pressure loss and lower power consumption of the pump.

Modeling and characteristic analysis of viscous resistance in annulus gap of coalbed gas well drainage pump

The viscous resistance caused by the relative motion of plunger and pump barrel is an important factor in the dynamic analysis of the drainage and production mechanism during coalbed methane exploitation. Existing studies mostly focus on deep well (1000–3000 m) large-displacement pump (usually 80–300 m3/d), and the interstitial medium is mainly crude oil. Regression fitting is mainly carried out based on empirical formula or experimental simulation method, without considering the characteristics of shallower coalbed gas well (400–800 m) small-displacement pump (<10 m3/d). The variation of the clearance between plunger and barrel and the variation of viscous resistance between plunger and barrel are not revealed. Based on the Navier-Stokes equation and Newton's internal friction law, a mathematical model of the annular viscous resistance between the plunger and the pump barrel is established, and an analytical method is used to describe the influence of stroke times, annular clearance, and differential pressure between the upper and lower plungers on the viscous resistance. The results show that the plunger stroke is directly proportional to the variation range of viscous resistance, and low stroke is beneficial to reduce the viscous resistance. The effect of differential pressure between upper and lower plunger of rod pump on viscous resistance of small displacement coalbed gas well is significantly greater than that of plunger running speed. The annular clearance is directly proportional to the differential pressure between the upper and lower parts of the plunger, the inertia force of the plunger, and the shear force of the moving fluid. The annular viscous resistance model between plunger and pump barrel is helpful to improve the calculation accuracy of suspending point load of coalbed gas well pumping unit, analyze the working condition of coalbed gas drainage gas production process, and provide basis for the optimization design of coalbed gas well rod pump clearance.

Analysis of output performance of all-metal progressive cavity motor

At present, the traditional progressive cavity motor is usually a rubber stator and metal rotor, and an interference fit is set. When it encounters the high-temperature formation of 180 °C and above, the carbonization of the rubber stator causes motor failure. Therefore, the all-metal progressive cavity motor adopts a metal stator and metal rotor, and the clearance fit is installed, which has good high temperature and corrosion resistance. The leakage caused by the clearance fit is the main reason for its performance output loss. Therefore, this paper is based on the leakage mechanism of all-metal progressive cavity motor and relies on the Couette flow, Poiseuille flow, and Bernoulli's theorem. Then the mathematical model of leakage and output performance of ∅95mm all-metal progressive cavity motor is established in this paper. The 3D-surface nephogram of the model about the effects of differential pressure, density, viscosity, and clearance on motor leakage was calculated numerically and iteratively by Matlab software. At the same time, through the calculation of the motor power loss of the structure design in this paper, the power loss is smaller in the clearance range, which provides a reference for the clearance selection of this kind of motor manufacturing. Finally, according to the mathematical model of the optimal clearance of 0.3 mm in the actual working conditions, the performance curve of the numerical calculation of the motor is demonstrated through the fluid simulation. Then the performance curve is compared and verified by the experiment of the InFocus company, which provides theoretical guidance for reducing leakage of motor and improving output performance.

Differential effects of pressure on social contagion of memory.

Collaboration can support performance on a variety of tasks, but recent projects have indicated that group collaborations can also be associated with memory decrements. For example, when people discuss ideas, any shared inaccurate information can be used by group members to complete subsequent tasks. Across two experiments, we examined whether this social contagion is influenced by performance pressures that regularly emerge during group interactions. In Experiment 1, participants under individual-directed pressure, goal-directed pressure, or control conditions studied word lists before completing a collaborative recall with a confederate partner who occasionally recalled incorrect words. We examined whether partner-produced inaccuracies contaminated participants' memories for the list contents on a subsequent individual recall. Goal-directed pressure, focused on monitoring partner accuracy, facilitated subsequent individual recall, as demonstrated by reduced reproductions of partner-generated inaccuracies. In contrast, individual-directed pressure, focused on appearing competent, resulted in greater use of those inaccuracies. Experiment 2 ruled out that the benefits associated with goal-directed pressure were solely due to warning participants about the possibility of social contagion. These results demonstrate that different instantiations of pressure can help or hinder memory-related performance in collaborative settings. Under the right conditions, pressure can help overcome the effects of exposure to inaccurate information. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Study on the Influence of High Temperature and High Speed Working Conditions on the Leakage Characteristics of Flexible Bristle Brush Seal

Compared with the metal bristles, the flexible bristles can reduce the heat and wear caused by the friction between the bristles bundle and the rotor, and improve the working stability and working life of the brush seal. In this paper, the L-shaped numerical mode is established to analyze leakage characteristics of flexible bristle brush seal. The flow field of brush seal is analyzed, and the effects of differential pressure, rotating speed and temperature on the leakage rate were studied as well. The leakage rate of the flexible bristles brush seal under different pressure and rotating speed was measured and compared with the numerical results. The results show that: Pressure drop mainly occurred in bristles pack; Small pressure difference, high temperature and high speed can improve the sealing performance, which, shows that the flexible bristles brush seal can well adapt to high temperature and high speed conditions; The leakage rate after running-in is slightly lower than that before running-in, and has better sealing performance, and the brush bristles arrangement is complete and tight after test, indicating that the flexible bristle brush seal has the ability of lasting and stable seal; The error between experimental results and numerical simulation results is less than 10%, and the variation trend is consistent, confirming the accuracy of the leakage rate obtained by numerical simulation.

Development of a High Differential Pressure Piezoelectric Active Proportional Regulation Valve Using a Bending Transducer

In this article, a piezoelectric active proportional regulation valve with high differential pressure is proposed based on a bending transducer. The output flowrate of the valve can be accurately controlled by a bending transducer. The configuration design and driving principle of the valve are presented and analyzed. The static analyses are performed to determine the structural parameters of the valve and deduce its transient overflow gap. On this basis, the overall flowrate model of the valve is established using the theory of circumferential flow and extended Bernoulli equation. The effects of differential pressure and driving voltage on output flowrate are clarified. A prototype of the valve is manufactured and the experimental setup is also established to evaluate the performances of the valve. The results indicate that the proportional regulation of the valve can be achieved by changing the driving voltage; the valve displacement and response time under no liquid-loading condition are 16.16 μm and 340 μs at the voltage of 300 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p-p</sub> ; the maximum output flowrate is 286.3 mL/min under the differential pressure of 344.75 kPa, and the leakage level is 0.11%; the maximum cut-off pressure of 275.8 kPa can be realized; the corresponding input power is 185 mW.

Effects of pressure, shear, temperature, and their interactions on selected milk quality attributes

The effects of pressure, temperature, shear, and their interactions on selected quality attributes and stability of milk during ultra-shear technology (UST) were investigated. The UST experiments include pressure (400 MPa) treatment of the milk sample preconditioned at 2 different initial temperatures (25°C and 15°C) and subsequently depressurizing it via a shear valve at 2 flow rates (low: 0.15-0.36 g/s; high: 1.11-1.22 g/s). Raw milk, high-pressure processed (HPP; 400 MPa, ~40°C for 0 and 3 min) and thermal treated (72°C for 15 s) milk samples served as the controls. The effect of different process parameters on milk quality attributes were evaluated using particle size, zeta potential, viscosity, pH, creaming, lipase activity, and protein profile. The HPP treatment did not cause apparent particle size reduction but increased the sample viscosity up to 3.08 mPa·s compared with 2.68 mPa·s for raw milk. Moreover, it produced varied effects on creaming and lipase activity depending on hold time. Thermal treatment induced slight reduction in particle size and creaming as compared with raw milk. The UST treatment at 35°C reduced the effective diameter of sample particles from 3,511.76 nm (raw milk) to 291.45 nm. This treatment also showed minimum relative lipase activity (29.93%) and kept milk stable by preventing creaming. The differential effects of pressure, shear, temperature, and their interactions were evident, which would be useful information for equipment developers and food processors interested in developing improved food processes for dairy beverages.

Effect of differential pressure on the transcription rate of micro-featured components

Vacuum casting is a widely employed method for small batch production of plastic prototype parts by the use of silicone rubber mold. However, some undesired defects of the cast part such as micro-bubbles, voids, weld lines, shrink mark, sink marks, warpage, blister, or short shot are observed in the conventional vacuum casting process. Vacuum differential pressure casting (VDPC) can overcome these drawbacks because of the filling mechanism of the casting material is different from conventional vacuum casting process. In this study, the VDPC was proposed to enhance the quality of casting parts. The process parameters related to the VDPC are investigated theoretically. Fabrication of components with microstructures using VDPC was investigated experimentally. It was found that the quality of VC parts with microstructures can be improved significantly using the VDPC. The transcription rate of the depth of the Fresnel lens can be increased from 41.9 to 99%.

Damage mechanism of cement slurry to CBM reservoirs with developed fractures and cleats: A case study from eastern Yunnan and western Guizhou in China

The coalbed methane (CBM) reservoirs in the areas of eastern Yunnan and western Guizhou are characterized by developed cleats and fractures and low fracturing pressures, so cementing slurry (“slurry” for short) can invade into CBM reservoir easily, resulting in reservoir damage and abnormal increase of reservoir transformation fracturing pressure. In order to reveal the damage mechanisms of slurry to this type of coal reservoirs, we analyzed the physical and chemical properties and potential damage modes of coal rocks. Then, the development situations of fractures and pores before and after the coal core samples were internally contaminated and the invasion and plugging situations of slurry in fractures and pores were analyzed intuitively by means of CT scanning and scanning electron microscope (SEM), and the percentage of slurry and fractures in coal core volume was calculated. In this way, a method to quantitatively evaluate the damage of slurry to coal reservoirs was established. And the following research results were obtained. First, under the effect of differential pressure, slurry and its filtrate invade into coal reservoirs along the fractures. The invasion degree varies with the development degree of fractures and pores. The more developed the fractures and pores, the higher the invasion degree. Second, the cement products formed after the slurry in the reservoirs gets cemented and solidified fill the fractures and pores tightly and cover the surface of coal core samples densely, so CBM flowing channels are blocked severely. Consequently, the permeability of coal core samples decreases and the compressive strength of coal rocks increase, leading to the abnormal increase of subsequent fracturing pressure and impacting the fracturing stimulation effects. Third, the effect of slurry filtrate on the alkali sensitivity and velocity sensitivity of coal rocks is much less than the damage degree of slurry invasion to coal rocks. In conclusion, this newly developed quantitative evaluation method for the damage of slurry to coal reservoirs is of guiding significance to improving the cement job quality of coal reservoirs and ensuring the efficient CBM development.

Mass flow rate of fine and cohesive powders under differential air pressure

Air-powder interactions are of practical importance in the production of pharmaceuticals, food and high value added chemicals manufactured using powders. For examples, air-powder effects enable consistent and effective dosing of fine cohesive powders into dies on high productivity rotary presses due to the suction fill effect.A purpose built experimental testing rig was developed and calibrated in order to develop a basic understanding of effect of air pressure on the mass flow rate of fine and cohesive powders. The powder materials were selected to enable the study of the effect of particle properties, such as size and density, and processing conditions such as differential air pressure, on the mass flow rate of powders.The models available in the literature developed for coarse free flowing sands under differential pressure were found inadequate to describe the experimental observations and to predict the flow behaviour of fine and cohesive powders. A new powder flow model was developed using established dimensional analysis methods based on the experimental data. The proposed model includes terms that account for the effect of differential pressure and reduces to the classic Beverloo model in absence of differential pressure. The model was validated and can be used for formulation and process design for flow regimes where air-powder interactions are important.

Modeling of filtration and mudcake buildup: An experimental investigation

This paper presents an experimental investigation and modeling of filtration and mudcake buildup during wellbore drilling. Extensive studies have been performed on this topic over the past seven decades and their general findings are summarized. In particular, the filtration model proposed in Dewan and Chenevert (2001) is discussed along with recommended methods for determining the model's parameters. New static filtration data were obtained using permeable filter discs manufactured from sand-cement mixtures to generate controlled formation material. The experimental results, consisting of fluid loss vs. time, mudcake porosity, and thickness at the end of the test, were used to evaluate the validity of the proposed methods and investigate the model's ability to predict the actual mudcake properties. Using the experimental results, some limitations of this model were identified. Therefore, modifications to Dewan and Chenevert's model were suggested to allow it to better capture the measured data, leading to the development of a new Wider Windows Filtration Model. Last, the effects of differential pressure, solids content of the mud, and filtration control agent on filtration and mudcake properties are presented and discussed.

Simulation of single-phase liquid flow in Progressing Cavity Pump

Progressing Cavity Pump (PCP), also known as Moineau pump, is an artificial lift method often used for pumping high viscosity and high solids content fluids from producing wells. Although, PCP has been effectively adopted in oil industry for decades, there is a lack of understanding the effect of its design parameters and operating conditions on the pump performance. The objectives of this study are to develop a model for predicting an actual multi-lobe PCP performance, and to investigate pump performance through simulating single-phase liquid flow behavior. The proposed model is a combination of two existing models in the literature, namely an analytical model to predict the theoretical pump performance, and a slippage model. The proposed model can be used not only to predict the actual multi-lobe PCP performance, but also to optimize pump design under given operating conditions. To validate the modeling results, an experimental study was carried out using a commercial PCP. The experiments were conducted with liquid viscosities ranging from 0 to 450cp, rotational speeds ranging from 0 to 300RPM, and pump differential pressures ranging from 0 to 300psi. The validation study revealed satisfactory results and reasonable match between the model predictions and experimental results. Using the developed model, an extensive sensitivity analysis was performed, which suggested that higher viscosity, in most of cases, minimizes pump slippage. In addition, if the pump clearance is smaller than a specific value, then the effects of differential pressure and liquid viscosity on the pump performance are minimal. Similarly, if the pump clearance is less than a specific value, then a pump with higher stator lobe number will deliver higher actual pump rate. The results of this study are not only important for manufacturers to optimize PCP design, but also for operators to improve PCP operational pump performance and pump efficiency.

A New Model for the Mechanochemical Corrosion of a Thin Spherical Shell

A pressurized thin-walled spherical shell under the conditions of double-sided uniform corrosion is considered. The rates of corrosion are supposed to dependent linearly on the effective stress. Previous solutions for thin shells obtained by other authors reflect only the effect of differential pressure (i.e., the difference between internal and external pressure). The model proposed here allows to include also the effect of hydrostatic pressure on the durability of the shell under the corrosion conditions.

Triangle wave pulsating flow effect on thrombus simulated by the lattice Boltmann method

As one of the major causes of cardiovascular diseases, the formation mechanism and the external factors of blood embolism are always the concerned problems of medical field, biological and physical field. Owing to thrombotic formation and structure being complicated, the difficulty in curing thrombosis greatly increases. Pulsation flows have a positive effect on dredging blood embolism. Owing to the blood viscosity and the inertia of red blood cells, waveform, amplitude and frequency of pulsating flow will influence the effect of dredging blood embolism. The research in this paper is mainly based on the lattice Boltzmann method. In conical pipe with embolism, in order to explore the influences of triangle wave pulsating flow waveform, the effects of differential pressure and frequency on vascular thrombus are studied by calculating the effect of dredging blood embolism. Calculation shows that the effect of dredging blood embolism is not obvious under the condition of low frequency and low differential pressure. On the contrary, the effect is good under the condition of high frequency. Appropriately increasing the differential pressure can also improve the frequency of the triangular wave of the bolt.

Microscale phase separator for selective extraction of CO2 from methanol solution flow

This study is aimed at understanding the limits in reducing the size of a membrane-based CO2 separator and its pressure head needs and energy consumption, while maximizing its selectivity. The separator consists of a flow channel capped by a hydrophobic nanoporous membrane through which CO2 exits the anode flow stream of a direct methanol fuel cell (DMFC). A systematic study is conducted to determine the effect of differential pressure across the membrane, flow velocity, and flow channel dimensions on the separation process. The extraction flux was found to change linearly with pressure difference across the membrane. The effect of flow velocity on the extraction flux was negligible up to a critical velocity beyond which the separation process ceased. The separation selectivity enhanced by increasing the differential pressure across the membrane but did not change with varying the flow velocity and channel depth. Using the findings of the first part of the study, an optimal micro-separator (with a footprint of approximately 10 × 1 mm2) was designed/fabricated for a 20 W DMFC and its performance was experimentally analyzed. An unprecedented separation selectivity of close to 200 was achieved at a differential pressure of about 10 kPa and negligible energy consumption.

Analysis of Mechanical Seal Leakage within Hydrostatic on Nuclear Reactor Coolant Pump

According to the fluid hydrodynamic lubrication theory, and the structural characteristics of the convergence gap seal is combined, the effect of differential pressure and centrifugal force should be considered, then the convergent wedge gap mechanical seals flow field numerical model is established and the influence of the leakage factors are researched, including the geometric parameters and operating parameters. Research has shown that the amount of leakage and the seal clearance were positively correlated. And the larger turning Angle is, the bigger correlation becomes, however, it is negatively correlated with speed and turning radius, the seal leakage is impeded by the centrifugal force and the larger turning radius is, the smaller leakage becomes.

The Experimental Research of the Restricting Factors of Water Invasion of Yulou Reservoir in Jin 45 Block

Jin 45 block has entered the later period of cyclic steam, Transforming the development mode is imminent,there is a big technical risks in the development of cyclic steam of edge and bottom water of heavy oil when it turns to steam flooding development, it is needed to understand the characteristics of Edge-bottom water which invades in reservoir and master the restricting factors of invasion of the edge-bottom water,to avoid the risk of steam flooding development reasonably and effectively. The experiment uses the three layers of inhomogeneous Artificial core which has high permeability transition zone of simulative edge water on the edge. Analysis the factors of differential pressure, temperature and distance of the water and bottom water to the effect of Edge-bottom water encroachment sensitivity. The results show that: Among many factors of water encroachment sensitivity, the effect of differential pressure to the regularity of water invasion is most obvious, at the stage of Connection of water invasion, the differential pressure has a little effect on the Instantaneous water influx, After the channel of water encroachment has formed,Instantaneous water rate and differential pressure is index function relation, in the late of water invasion, the instantaneous water rate is stable. The result provides the basis for the heavy waterflooded area turn to steam flooding.

The Effects of Compression Pressure Applied on the Manufacture of Carbon Composite Bipolar Plate for PEMFC by Utilizing Graphite Waste Products

Proton electrolyte membrane fuel cells (PEMFC) have near zero carbon dioxide and hazardous pollutant emission. Thus, it is considered as one of energy sources for transportation and other application which can improve environmental performance by decreasing the emission of greenhouse gases and other air pollutant. In accordance with its environmental preservation values, graphite waste product from electric arc furnace (graphite EAF) was chosen as a potential candidate material for bipolar plate for PEMFC. The utilization of graphite waste product is expected to result in light-weight and cost-effective bipolar plates. In this paper, we used graphite EAF as a filler together with carbon black and epoxy resin as a binder. We examined the effects of differential pressure applied on compression molding process on density, porosity, flexural strength and electrical conductivity of the resulting carbon polymer composite bipolar plate. Pressure was applied from 30 MPa - 60 MPa in increments of 5 MPa while maintaining constant temperature operation at 700C for 4 hours. Maximum value of bipolar plate density was achieved at application 55 MPa, of 1.69 g/cm3. At this condition, the flexural strength was measured to be 48 MPa with the porosity of 0.7%, and electrical conductivity of 1.03 S/cm. Taken together, we demonstrated that graphite EAF is a good candidate for the manufacturing of polymer composite bipolar plates.

The use of computational fluid dynamic models for the optimization of cell seeding processes

The seeding of a porous scaffold with stem cells is a fundamental step in engineering sizeable tissue constructs that are clinically viable. However, a key problem often encountered is inhomogeneous seeding of the cells particularly when the cells are delivered through the thickness of the scaffold. The objective of this study was to establish the quantitative relationships between the cell seeding efficiency and the initial vacuum pressure in a compact perfusion seeding device that uses the effect of differential pressure induced by vacuum to seed cells on a porous scaffold. A transient CFD solution of the fluid flow in the device was used to optimize the initial vacuum pressure for efficient cell seeding. Results indicate that the optimal initial vacuum pressure for homogenous cell seeding is approximately −20 kPa for the seeding device. This study presents a 3-D computational model that can be employed in designing and optimizing cell seeding techniques and corresponding technology.

Extension of Das and Butler Semianalytical Flow Model

Summary In this work, the Das and Butler flow model was extended to account for the effect of differential pressure across a laterally and vertically spaced horizontal injection- and production-well pair for solvent vapour extraction (SVX) processes. The extended model provides a more-rigorous dispersion-coefficient correlation using interstitial pore velocity and mean particle size. This was used to history match oil-production data from 3D-scaled physical model experiments and to determine the effective dispersion coefficient of the solvent in heavy oil. The SVX experiments were performed with two model sizes and three different permeabilities spanning than two orders of magnitude. Laterally spaced horizontal wells were used to inject an 86:14 mol% mixture of butane and methane, respectively, as a dense vapour. The average dispersion coefficient of solvent (butane) was found to decrease with injected cumulative solvent and increase with reduction in permeability, and both of these relationships could be approximated with an inverse power function.