Differential Pressure Flow Research Articles

Fuzzy Interpretation of the Discharge Coefficient for the Orifice Plate of Automated Flow Rate Measuring Systems

ABSTRACT Differential pressure flowmeters play a key role in the organization of flow rate measurements of liquids and gases in various industries. Therefore, the tasks related to improving their accuracy and the convenience of forming various dependencies between the values on which the accuracy of flow rate measurement depends are very important. One of the main characteristics that determines the correct and accurate operation of differential pressure flowmeters is the discharge coefficient. In this paper, the authors present a methodology that allows us to present this coefficient as a fuzzy model. The paper presents an original method for modeling the existing discharge coefficient in the form of a fuzzy model that is able to change the existing classical equation. A comparative analysis of the fuzzy and classical models is performed for this discharge coefficient. The article analyzes the errors of the fuzzy model for the discharge coefficient, discusses ways how to reduce the error of the fuzzy model. The proposed methodology describes the application of the fuzzy model for this coefficient within the existing limits for the Reynolds number and diameter ratio. It is shown that for a more accurate approximation of the characteristics, it is necessary to add more fuzzy sets. The present method is feasible for diameter ratio and Reynolds number greater than 5000. The article also discusses the possibilities of using fuzzy models to improve the characteristics of differential pressure flow meters.

Calibration of Winter-Kennedy coefficients on a Bulb turbine based on current-meter method

Field measurement of discharge has been performed for a Bulb turbine based on current-method in this paper. Winter-Kennedy coefficients of this machine are calibrated based on the test results of integrated discharge and measured flow differential pressure between bulb head and stay cone. Calibration shows that discharge and flow differential pressure of the test machine follow the power model very well. The uncertainty of discharge estimation by Winter-Kennedy method for Bulb turbine is discussed finally.

Effect of different upstream fittings on orifice meter performance. (Dept. M.)

Orifice meters are a type of the differential pressure flow meter widely used in industrial applications dealings with measuring the size and flow rate of expensive fluids such as natural gas, petroleum and water. The measurements accuracy of these meters depends mainly on their position in a pipe network. This paper is concerned with the effect of nonstandard flow conditions generated by various fittings (e. g: reducer, single elbow, double-elbow in- plane, double-elbow out-of- plane, T-junction) at different nonstandard upstream distances of the orifice plat on velocity profile and on discharge coefficient. Both numerical and experimental studies were used to investigate this problem. The results show that for each fitting, there is a different effect on the velocity profile and on the discharge coefficient. As an example, the 90° elbows decreases the discharge coefficient with decreasing upstream distance and increasing Reynolds number. Also, after a straight distance of 40D between the elbow and the orifice plate, the velocity profile is not fully matched with the normal profile.

Research on fluid flow mechanism of fracture-cave carbonate reservoirs based on fluid mechanics

ABSTRACT Facture-cave carbonate reservoir has not formed mature development theory and method up to now, and the development is world-class difficult problems, which are caused by that it is not clear to understand the particularity of reservoir characteristics and fluid flow mechanism. Because karst caves are the dominant reservoir space and production contributor, porous flow mechanics is not applicable. Reservoir body belongs to neither porous media nor continuum as a whole, hence fluid flow belongs to the research category of fluid mechanics. Contrary to widely adopted coupling method, this paper will focus on the fluid flow mechanism by only applying the theory of fluid mechanics and ignoring porous flow on the basis of analyzing the particularity of reservoir characteristics. Both capillary pores in carbonate matrix and slender dissolved cavities can be regarded as hydraulic long pipe, and fluid flow conforms to pipe flow law. Fluid flow in fracture belongs to parallel plate clearance differential pressure flow, which is similar to pipe flow. Fluid is static under gravity and fluid flow conforms to hydrostatics law in approximately equiaxed karst caves, and fluid flow out of karst cave is orifice outflow. Porous flow in reservoirs is unified with pipe flow. The essence of porous flow is the macro performance of pipe flow in countless capillary pores, which manifests as Darcy’s law under laminar condition. Porous flow in carbonate matrix can be completely ignored because it is extremely difficult to occur and the effect is very tiny. In dissolved-cavity reservoir body of millimeter scale, fluid flow is mainly slight pipe flow and gravity effect is significant, which leads to tiny production pressure differential and pressure drop funnel. In karst-cave reservoir body of meter scale, there is no fluid flow nor pressure drop in horizontal direction and the displacement of oil by water is piston-like displacement vertically upward in karst caves, hence pressure drop funnel does not exist at all. The production pressure differential generated by orifice outflow at the outlet of karst cave is very tiny and can be ignored. The new fluid flow mechanism based on fluid mechanics will provide theoretical basis for solving the difficult problems of developing fracture-cave carbonate reservoirs.

Design of a high-pressure viscosity-measurement system using two pressure balances

In this paper, a new high-pressure viscosity measurement system using a capillary method is reported. In this system, two pressure balances are used to generate stable pressure and flow field in the capillary. The volumetric flow rate was measured by calculating the change in the piston fall rate. To check the effectiveness of the method, the viscosity of bis(2-ethylhexyl) sebacate was measured at pressures of up to 200 MPa. Differential pressure and volumetric flow rate had a linear relationship at all temperature and pressure conditions, indicating that the Hagen–Poiseuille law can be applied in this method. The viscosity–pressure dependence is in agreement with other published reports. Thus, we confirmed that the newly developed high-pressure viscosity measurement system can accurately evaluate the pressure dependence of viscosity.

EXPERIMENTAL STUDIES ON PRESSURE DROP CHARACTERIZATION OF CURVED TUBE SECTIONS IN LAMINAR FLOW REGIME

Flow measurement is an important task in many engineering applications. There are various methods available for flow measurement like differential pressure flow meters, displacement flow meters, and velocity flow meters etc., which indirectly measure the mass flow rate of a fluid. Whereas direct mass flow measurement devices like Coriolis Mass Flow Meter (CMFM) are, nowadays, gaining attention due to high accuracy and reliability. In practice, most of the times, flowing fluid is quite often turbulent and hence, the studies on flow field had been around turbulent flow regime. Generally, higher velocities have been found in the turbulent regime. However, as the fluid viscosity increases there can be increase in the mean velocity in the proportion such that the flow still remains laminar. The performance of CMFM is found to be deviated in this flow regime leading to underestimation of the flow rate as reported by Kumar and Anklin [1]. Bobovnik et al. [2] carried out numerical simulations to predict the performance of shell type Coriolis flow meter for a range of Re with the tube of two different aspect ratios. The velocity profile effect was presented in terms of anti-symmetric fluid forces which resulted in a loss of sensitivity at low flow rates. Kutin [3] presented a numerical study on the velocity profile effects for two straight tube configurations, one operating in a beam-type mode and other in a shell-type mode and reported that in both the cases, the meter sensitivity was affected. The author highlighted the intensive deviations in flow meter sensitivity at low Re. This can lead to a substantial economic loss in Petroleum industries. The literature review of CMFM in the laminar region has highlighted the development of secondary flow phenomenon in curved tube sections leading to under-read the meter in this region. The issue of under reading in case of CMFM needs attention and thereby remedial solution as an outcome of research.

A novel comprehensive correlation for discharge coefficient of square-edged concentric orifice plate at low Reynolds numbers

Among various differential pressure flow meters, the orifice meter has gained its publicity in applications where cost, space, and ease of maintenance are of high priority. A major problem associated with the use of orifice flow meters at low Reynolds number flows is the significant variation of discharge coefficient (Cd) as a function of orifice geometry and the Reynolds number. In this work, a two-dimensional axisymmetric numerical model was applied to the investigation of viscous, incompressible flow through square-edged concentric orifice plate for the purpose of studying the performance of discharge coefficient consequent to variations of Reynolds number (Re), orifice/pipe diameter ratio (β), and orifice thickness ratio (t*). The analysis of numerical results by means of multiple regression method has yielded a new correlation incorporating the effect of the parameters under study on orifice meter discharge coefficient for orifice bore Reynolds numbers (Reo) < 250. Results of relevant investigations from the literature are used in the present work as references for the validation of the numerical model as well as the proposed correlation for discharge coefficient.

The Investigative Study on the Small-sized Isolation Device: regarding of the isolation performance and function test In Emergency Disaster Circumstances

The first case of Middle East Respiratory Syndrome (MERS) was reported in Korea in 2015, after a Korean man from Bahrain tested positive for the infection. After first eruption, there were numbers of secondary infectees and whole country were frightened. At the time, isolated ambulances were available but few, and there was no specific way to prevent contamination during transfer. Therefore, Seoul National University Hospital and the University of Seoul developed isolation units and air filters. Four years after the MERS outbreak, this study measured the differential pressure inside and outside the small isolation units based on the differential pressure and air flow derived from simulation and testing, and proposed minimum values for virus leakage and internal sealing. A performance evaluation and testing method for the transfer equipment is proposed. The critical function of the small isolated transport equipment was defined and selected as an evaluation item; performance evaluation was carried out by simulating a real-world case. The results provide the proper pressure configuration of positive and negative pressure inside the segregation feeder; the clear criteria for the HEPA filter; and the performance criteria for the segregation feeder and air purifier.

Comparative CFD modelling of pressure differential flow meters for measuring two-phase geothermal fluid flow

Computational fluid dynamics (CFD) models solved using ANSYS Fluent to simulate the two-phase geothermal fluid flows in production pipelines using six types of flow meters: concentric orifice, top eccentric orifice, bottom eccentric orifice, segmental orifice, Nozzle and Venturi tubes. The CFD models were then developed to predict fluid flow behaviour, including net pressure drop, velocity, turbulent kinetic energy, mass flow rate, temperature, enthalpy and entropy. The results are useful for selecting the appropriate pressure differential flow meter to measure the output of geothermal wells and their total power potential, which is of most importance to the geothermal industry.

Approximate Solution of the Problem on Elastic-Liquid Filtration in a Fracture Formed in an Oil Stratum

With the use of theoretical models of filtration liquid flows in fractures of finite and infinite lengths, formed in an oil stratum, the problem on the production of oil from a well, operating in the regimes of constant differential pressure or constant flow rate in this stratum, was solved. On the basis of approximate solution of the problem on the flow of oil from a stratum into a fracture formed in it by the method of successive changing stationary states, fairly simple analytical formulas have been obtained. A comparison of the results of numerical calculations of the practically important parameters of an oil stratum and a hydraulic fracture in it by the approximate formulas constructed and the corresponding exact formulas, which are much more complex than the approximate formulas, has shown that these results are almost identical. In particular, the errors in determining the evolution of the pressure field in a well and its flow rate by the approximate formulas did not exceed several percent. On the basis of numerical analysis of the approximate solutions obtained, the influence of the porosity and permeability of the stratum, the length of a fracture in it, and the rheological properties of the liquid saturating the stratum on the evolution of the pressure in the fracture, the flow rate of a well operating in the regime of constant differential pressure in the stratum, and the changes in the pressures in the fracture and in the well at a constant well flow rate was investigated.

Hydrate Growth on Methane Gas Bubbles in the Presence of Salt.

Methane bubble dispersions in a water column can be observed in both vertical subsea piping as well as subsea gas seepages. Hydrate growth has been shown to occur at the gas-water interface under flowing conditions, yet the majority of the current literature is limited to quiescent systems. Gas hydrate risks in subsea piping have been shown to increase in late life production wells with increased water content and with gas-in-water bubble dispersions. The dissolution of subsea methane seepages into seawater, or methane release into the atmosphere, can be affected by hydrate film growth on rising bubbles. A high-pressure water tunnel (HPWT), was used to generate a turbulent, continuous water flow system representative of a vertical jumper line to study the relationship between bulk methane hydrate growth and bubble size during a production-well restart. The HPWT comprises a flow loop of 19.1 mm inner diameter and 4.9 m length, with a vertical section containing an optical window to enable visualization of the bubble and hydrate flow dynamics via a high-speed, high-resolution video camera. Additional online monitoring includes the differential pressure drop, viscosity, temperature, flow rates, and gas consumption. Experimental conditions were maintained at 275 K and 6.2 MPa during hydrate formation and 298 K and 1.4 MPa during hydrate dissociation. Hydrate growth using freshwater and saltwater (3.5 wt % NaCl) was measured at four flow velocities (0.8, 1.2, 1.6, and 1.9 m s-1). The addition of salt is shown in this work to alter the surface properties of bubbles, which introduces changes to bubble dynamics of dispersion and coalescence. Hydrate volume fractions and growth rates in the presence of salt were on average ∼32% lower compared to that in freshwater. This was observed and validated to be due to bubble size and dynamic factors and not due to the 1.5 K thermodynamic inhibition effect of salt. Throughout hydrate growth, methane bubbles in pure freshwater maintained larger diameters (2.4-4.2 mm), whereas the presence of salt promoted fine gas bubble dispersions (0.1-0.7 mm), increasing gas-water interfacial area. While gas bubble coalescence was observed in all freshwater experiments, the addition of salt limited coalescence between gas bubbles and reduced bubble size. Consequently, earlier formation of solid hydrate shells in saltwater produced early mass-transfer barriers reducing hydrate growth rates. While primarily directed toward flow assurance, the observed relationship between hydrates, bubble size, and saltwater also applies to broader research fields in subsea gas seepages and naturally occurring hydrates.

Estimation Optimal Value of Discharge Coefficient in a Venturi Tubes

Development of an accurate and reliable differential pressure flow meters is needed for industry. The relationship between the Reynolds number (Re) and the discharge coefficient (Cd) was investigated using a differential pressure flow meter. Venturi meter is a type of baffle meter, widely used in industry for flow measurement. The ISO standard (ISO-5167-1) provides discharge coefficient values for classic Venturi tubes in turbulent flow with Reynolds number values above 2x105. This study shows that various discharge coefficient decrease rapidly and constant discharge coefficient values vary with meter design. The main focus of this study is to compare experimental results with theoretical predictions and estimate the optimal value of thevmeter discharge coefficient at various flow rates. The experimental results showed that the optimal value of the venturi tube discharge coefficient of about 0.983 was obtained.

Effect of Reflux Hole on the Transient Flow Characteristics of the Self-Priming Sewage Centrifugal Pump

The reflux hole has a large effect on the performance of self-priming centrifugal pumps. In order to study the effects of the reflux hole on the performance and transient flow characteristics of the self-priming centrifugal pump, four different areas of the reflux hole inside an external mixed self-priming pump were proposed. The 3D transient flow was numerically simulated under different operating conditions for the investigated pump. The differential pressure, reflux quantity and transient flow characteristics near the reflux hole were analysed, and then the effects of the reflux hole area on the pressure fluctuation characteristics and performance of the pump were further researched. The results show that the differential pressure and reflux quantity is zero around the best-efficiency point. The vorticity magnitude near the exit of the reflux hole is significant, and the unsymmetrical flow structures represent periodic motion over time in the cross-section. The pressure fluctuation intensities of monitoring points P2-P5 upstream of the reflux hole were generally larger than others and decreased with a decrease in reflux hole area. With a decrease of the reflux hole area, the performance of the pump improved to some extent.

공조설비내 에어필터와 UVGI 설치에 따른 실내공기질 비교분석

In this study, we installed air filters and ultraviolet germicidal irradiation (UVGI), which are commonly used in HVAC systems to prevent the spread of contaminated air and reduce the concentrations of airborne infectious agents in general hospital rooms, in a chamber designed for mock-up testing in order to measure the concentrations of dust particles (PM10) and airborne bacteria and analyze the HVAC differential pressure, air velocity, and air flow rate losses. Based on the measurement and analysis results, we identified an air filter and UVGI installation method for optimal prevention of the spread of contaminated indoor air. Air filter F1 [Pre-filter + HEPA filter] and F2 [pre-filter + 2 medium filters] were efficient in reducing the concentrations of PM10 and airborne bacteria, and UVGI was efficient in reducing the concentration of airborne bacteria. F2 outperformed F1 in reducing PM10 and airborne bacteria concentrations, and F2 was also found to be more effective in terms of differential pressure, air velocity, and air flow rate losses.

Experimental Investigation of the Impact of Coal Fines Migration on Coal Core Water Flooding

Coalbed Methane (CBM) has become an important gas resource in recent decades. The brittle property of coal matrix and overactive operation make the migration of coal fines inevitable. Blockage by coal fines that plugs flow paths is a non-negligible issue that results in a significant decline in gas production. By setting different experimental conditions with the following factors—coal fines concentration of the mixture displacing fluids, constant flow pump rate, inlet pressure, outlet pressure and confining pressure—six experimental schemes were designed to investigate the two-phase water and coal fines flow in natural core samples. When the differential pressure and flooding flow reach a pseudo-steady status, the equivalent permeability of coal samples can be approximately calculated considering coal fines migration. Furthermore, the influences of coal fines migration on the cleat opening and permeability variation are analyzed in the porous coal medium. The study will benefit CBM development and save pump maintenance costs. In this work, we found that maintaining the differential pressure for a longer period may result in new cleat openings and severe coal rock damage during the single-phase water flooding process. While coal fines may plug some natural cleats and pores, especially in the core samples with micro-cleats during the two-phase flooding stage, coal fines migration significantly reduces the equivalent permeability and dewatering ability of the coal rock in the earlier flooding. While enlarging the differential pressure in two-phase water and fines flooding, breakthrough of coal fines from the samples contributes to widened cleats. While coal fines are difficult to flood into the core pores for low-permeability core samples, coal fines gather in the inlet, and it is also difficult to reach the pseudo-steady status even under higher differential pressure. The damage to permeability mainly occurs in the early stage of coal fines migration, and an abrupt increase in the flow velocity can damage reservoirs and induce substantial coal fines generation. Thus, maintaining a stable effective strength and a controlled depressurization rate during drainage can effectively constrain coal fines output and decrease permeability damage within coal reservoirs.

Error Compensation Technique for a Resistance-Type Differential Pressure Flow Sensor

A flow sensor is designed based on resistance-type differential pressure flow (RDPF) method, and the flow data is measured during a coal gangue paste-filling process. The measurement error characteristics of a RDPF sensor are analyzed. Periodic and aperiodic errors are then modeled separately. The model for the periodic error is established by Fourier series approximation using least squares solution of an overdetermined equation to solve for the model parameters. The model for the aperiodic error is established using an online least squares support vector machine (LS-SVM) method. The cross-validation is used to solve model parameters. Simulations and experiments show that the dynamic measurement accuracy of the sensor is greatly improved by error compensation, thereby reducing filling material waste and improving the economic efficiency.

Non-active area water mitigation in PEM fuel cells via bipolar plate surface energy modification

The management of liquid water from either internal chemical reactions or externally humidified reactants is an important design consideration for proton exchange membrane (PEM) fuel cells because of the effects on both cell performance and durability. To achieve proper water management, significant effort has been devoted to developing new fuel cell materials, hardware designs, and appropriate stack operating conditions. However, water management in the region of the channel-to-manifold interfaces has received limited attention. This region covers the ends of the bipolar plate from where liquid water exits the active area to the entrance of the stack exhaust manifolds where excess reactant flows from individual cells are combined and leave the stack. For practical applications, there is a small driving force to expel liquid water in this region, especially in the anode flow field. Under severe operating conditions such as freezing temperatures, the buildup of water may cause a channel-scale blockage. In this study, hydrophilic and hydrophobic bipolar plate treatments were investigated to identify the effectiveness of water mitigation through ex-situ experiments performed using a dedicated freeze test rig. Water mitigation behavior with various locations of hydrophilic/hydrophobic coatings was characterized using measurements of differential pressure and gas flow rate. It was found that the hydrophilic coatings provide better performance, as water accumulation can be readily mitigated with less potential to cause full channel-scale blockages.

Development and Validation of the SAE J3052 High Pressure Differential Flow Rate Recommended Practice

Development and Validation of the SAE J3052 High Pressure Differential Flow Rate Recommended Practice

Method for measuring the pulsating flow of liquids and gases

Most of the measurement methods and models cost liquids and gases based on the assumption that the flow is stationary. However, very often flow the fluid or gas flowing through the pipeline system at working pumps and compressor stations, become unsteady. They are various kinds of pulsation that become sources of a large number of additional errors. The paper offers method for measuring the flow rate and quantity of pulsating fluid or gas flowing into the pipeline system. The work is based on the ideas that transform the existing fundamental equations of hydrodynamics by methods of dimensional analysis, in particular the Euler equations and the continuity of flow. These equations allow organizing the method of measurement and conversion function of flowmeter that is able to perform the measurement of pulsating flow. The paper shows that to achieve this goal, the equation of discharge coefficient of orifice plate or nozzle must contain the Strouhal number. The proposed method of measuring pulsating flow of liquids and gases is a combination of the variable differential pressure and vortex flow measurement. The proposed method can be easily implemented in the form of information-measuring system. The work is addressed to employees of enterprises, which runs development and operation of the flow measurement system.

Optimal Design of Orifice Flow Meter Using Computational Fluid Dynamics (CFD)

Orifice flow meter constitutes one of the most common differential pressure flow meters. However, high energy loss is occurred with the measurement process. The present research considers 3𝐷 steady simulation using Reynolds Averaged Navier–Stokes equations (RANS). New design of the orifice plate s carried out using the adjoint method. Optimal shape of orifice plate shows 55 % reduction of the pressure loss coefficient at a Reynolds number 𝑅𝑒=1.84 × 104. The discharge coefficient 𝐶𝑑 is increased by 39 %. Also, the effect of downstream ring is investigated. Optimize the shape of the ring has a slight effect on reducing energy consumed. However, applying adjoint method on the orifice plate with downstream ring achieves considerable effect in the pressure loss. Reduction by 34 % in pressure loss coefficient is obtained by the optimal orifice with downstream ring. Shape optimization by the adjoint method has a significant contribution in decreasing the consumed energy through the orifice meter.