Pressure Drop Rate Research Articles

A compositional numerical study in hydraulic fractured tight reservoir: Considering capillary pressure in phase behavior calculation

The compositional numerical simulator is a critical method for simulating the development of oil and gas production. In the simulation of conventional reservoir, capillary pressure is relatively small and often been ignored in phase behavior calculations. But In tight reservoirs, the capillary pressure is so large that can seriously affect the fluid phase behavior. The existing compositional numerical simulators cannot accurately calculate oil and gas production of tight reservoirs because the effects of capillary pressure on phase behavior are ignored. In this paper, we developed a full compositional numerical simulator that simulates the production in tight reservoirs with the consideration of capillary effect on the phase behavior of fluid. To compare the simulation results with and without considering capillary pressure in phase behavior calculations, we respectively set the capillary pressure as a function of gas saturation or zero in matrix and fractures. Three capillary pressure assignment methods for tight reservoirs were performed to illustrate the influence of capillary pressure on production. The simulation results indicate that the consideration of capillary pressure on phase behavior lead to more favorable for oil production, such as lower cumulative gas production and gas-oil ratio, accelerated pressure drop rate, increased oil saturation, and higher recovery compositions of heavy components. This study provides reasonable simulation results for the actual production of tight reservoirs, giving important insights into the evaluation of the production and development from tight reservoirs.

CFD study on the effect of various geometrical parameters of honeycomb type orifices on pressure drop and cavitation characteristics

Flow zoning devices in nuclear power plants are used to achieve desired pressure drop and flow rates. Cavitation in these devices may cause erosion, flow chocking, noise, vibration, resulting in severe damage. Optimization of flow conditions, geometrical parameters, and prediction of the hydrodynamics of the flow field are necessary to avoid cavitation in these devices. In the present study, Computational Fluid Dynamics (CFD) simulations have been carried out to model flow through honeycomb shaped orifices. The effect of various geometrical parameters such as flow area, the spacing between plates, number of plates, orientation between plates (inline or offset) on pressure drop, and cavitation characteristics has been studied. The multiphase mixture model (water-liquid and water vapor), in conjunction with the Schnerr and Sauer cavitation model, is used to model the flow through orifice plates. Axial distribution profiles and contours of vapor fraction and pressure coefficient have been plotted to analyze the cavitation characteristics for different plate configurations and to get a better understanding of the flow field. Lowest pressure values are observed at the orifice throat and near plate exit. Threshold flow velocities above which flow is subjected to cavitation have been identified for different geometrical configurations. An increase in the number of plates reduces the probability of cavitation. Reduction in the flow area of the orifice plate increases the cavitation potential and pressure drop. However, an increase in plate spacing enhances the pressure recovery and reduces non-uniformities in the flow field.

Role of Gas Viscosity for Shale Gas Percolation

Viscosity is an important index to evaluate gas flowability. In this paper, a double-porosity model considering the effect of pressure on gas viscosity was established to study shale gas percolation through reservoir pressure, gas velocity, and bottom hole flowing pressure. The experimental results show that when pressure affects gas viscosity, shale gas viscosity decreases, which increases the percolation velocity and pressure drop velocity of the free state shale gas in matrix and fracture systems. And it is conducive to the desorption of adsorbed shale gas and effectively supplemented the bottom hole flowing pressure with the pressure wave propagation range and velocity increasing, so that the rate of pressure drop at the bottom of the well slows down, which makes the time that bottom hole flowing pressure reaches stability shortened. Therefore, the gas viscosity should be fully considered when studying the reservoir gas percolation.

Features of the underground storages construction in depleted oil and gas condensate fields

The paper considers the features of the underground storages (US) construction in depleted oil and gas condensate fields (DOGCFs). The requirements for the structure of the formation, corresponding to the parameters of the object for possible US creation are presented.
 The influence of geological, hydrogeological, mining and technical rock formation conditions on the reliability and tightness of underground storages, including underground gas storages, has been evaluated. The necessary conditions for the US design are analyzed at the example of the Ach-Su oil and gas condensate field, in the presence of a well-explored trap with acceptable parameters for the construction of an underground storage. An important aspect is the geological conditions that meet the criteria for selecting the object: the required structure, the absence of fracturing faults, high reservoir properties of the formation, a sufficient volume of the deposit for the storage. Geological conditions lay the basis for determining the individual characteristics of the US construction technology at each DOGCF. The refined results for the current gas-saturated pore volume and the rate of pressure drop in the formation are presented, which makes it possible to select improved technological indicators in the course of operation of the created US. In order to select the optimal option for the design and construction of the US, the results of economic and geological scenarios analysis were studied concurrently with the capabilities of the technological operation of the object and transport system, which can ensure the maximum daily production of the storage.

Reaction of the Heart to High Frequency Stimulation against the Background of Acute Doxorubicin Treatment.

Short-term high frequency electrostimulation (8-10 Hz) of the isolated isovolumic rat heart rapidly increased the rate of pressure rise and drop and the diastolic pressure. At the same time, the relaxation rate constant (RRC), being independent of the developed pressure, remained unaltered. These findings suggested that diastolic pressure rise was not caused by incomplete myocardial relaxation. Doxorubicin (3 μM) moderately reduced the developed pressure, but the relaxation rate constant remained unchanged. The dynamics and degree of changes in all indicators of the cardiac contractile function in high-frequency stimulation were the same as in control. It can be hypothesized that the initial effect of doxorubicin was not related to ionic transport system disturbances in cardiomyocytes.

Role of Supercritical Nitrogen (SCN) on the hydraulic and thermal characteristics of futuristic High Temperature Superconducting (HTS) cables

Cryogenic fluids such as Liquid Helium (LHe), Liquid Nitrogen (LN2), Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) played a vital role in cooling various superconducting devices. The boiling temperatures of cryogenic fluids being lower than the critical temperature of the superconductors have enabled such an advantage. Moreover, supercritical fluids such as Supercritical Helium (SHe) and Supercritical Nitrogen (SCN) are also found to be replacing the liquid coolants thereby eliminating the possibility of reduction in heat transfer due to multiphase flow of working fluid. Hence, it is essential to investigate the role of such supercritical fluids in cooling the superconducting cables. Hence, in the present work, Super Critical Nitrogen (SCN) is proposed as a coolant for cooling of High Temperature Superconducting (HTS) cables. As the thermophysical properties are strongly affected by the temperature, analytical functions of thermophysical properties of SCN such as viscosity, density, specific heat and thermal conductivity are developed and implemented in the Thermohydraulic analysis of 1 m HTS cable. A 3-Dimensional computational model of HTS cable is modeled and developed in commercial software ANSYS-FLUENT for solving governing equations of mass, momentum and energy simultaneously. Different mass flow rates ranging from 16 L/min to 20 L/min and heat loads ranging from 1 W/m to 3 W/m are considered in estimating the thermohydraulic performance of HTS Cable. Friction factor, pressure drop, pumping power and heat transfer rate are estimated and compared with the results of experiments available in the literature. It can be concluded that SCN may be used as coolant to cool the HTS cables having higher critical temperature.

A New Method For Estimating The Peak Gas Rate

Every winter from November of the first year to March of the next year, gas consumption would roar. As a result, all gas fields will increase gas rate to meet the needs. Traditionally, peak rate and rational rate are usually determined by methods like pressure drop rate, Rate Transient Analysis (RTA) and numerical simulation. These approaches have been verified in the production, but they show flaws like heavy workload and poor time effectiveness. Theoretical research indicates that a plot of the increment of gas rate and the pressure drop rate should be linear, when pseudo-steady state is reached. In consequence, based on numerical simulation, correlations of the increment of gas rate and pressure drop rate were developed respectively for a series of reservoir pressure and well types. Field applications show that this method can not only process a huge batch of data in one time, but quickly estimate the rational and peak gas rate in real time.

An improving performance evaluation plot (PEP) for energy management in microchannel heat sinks by using nanofluids

Based on previous works, a performance evaluation plot (PEP) is presented to theoretically evaluate the techniques used in the determination of various thermophysical properties of fluids in energy saving. From it, PEP is divided into “three lines and four zones”. Zone-1 indicates enhanced heat transfer without energy-saving, and enhanced heat transfer are in Zone-2, Zone-3 and Zone-4 with energy-saving for a fixed pumping power, pressure drop and flow rate, respectively. Then, microchannel heat sinks (MCHS) with cavities and different ribs arrangements were designed and simulated by using water-Al2O3 nanofluids. Based on the estimation indicators of comprehensive thermal performance (PEP and the thermal enhancement factor η), all working points located in the Zone-3 and 4 indicate that the increase in the heat transfer ratio is higher than that in the friction factor. The maximum enhancement of η is 2.2517 and it is measured in an odd-symmetric ribs structure (Channel D) with Reynold number equal to 582. The reasons are that the arrangement of odd-symmetric ribs continuously interrupts the development of the flow and thermal boundary layers. Moreover, cavities facilitate the full mixing of cold and hot fluids and reduce pressure drop.

Analysis of particle deposition of nanofluid flow through porous media

A numerical investigation of nanoparticle deposition for flow through a partially filled channel subject to a constant heat flux boundary condition is presented. The discrete particle model (DPM) is utilized for the simulations. The Brinkman-Forchheimer extended Darcy model is used for the flow inside a saturated porous matrix. The effect of porous permeability (Da = 10−8–10−4), Reynolds number (Re = 500–2000), volume concentration (0%, 0.3% and 3%) and different particle forces on the deposition rate have been documented. The particle adhesion/detachment is solved with respect to the force balance considering drag, Saffman lift, Brownian, thermophoresis, gravity and Van Der Waals. Our results reveal that the mass deposition rate can be omitted when there is no porous media inside the channel. In addition, no heat transfer enhancement is noticed for low particle loading <1% of nanofluid compared to water for Da ≤ 10−5. It is found that, the porous permeability has a substantial role on nanoparticle mobility and a critical Reynolds number (500 ≤ Re ≤ 1000) exists where the entrapment rate is maximized. On the other hand, the particle velocities and mass deposition rates are high for volume concentration of 3% while accompanied by an increased rate of heat transfer and pressure drop, particularly for Da ≥ 10−5 when compared to 0.3% volume fraction. It was observed that increasing porous permeability to Da ≥ 10−4 decreases the deposition rate. The impact of different pertinent forces on the deposition was also considered, and our results establish that Brownian motion had the most dominant effect on the deposition rate in the presence of a porous medium.

Measurement of core flow distribution in a research reactor using plate-type fuel assembly

In the present study, the core flow distribution of research reactors that used a plate-type fuel was investigated by measuring the flow rates at all fuel assembly locations to determine the flow uniformity in the reactor core. A specially instrumented dummy fuel assembly called probe fuel was developed to measure the flow rate at each fuel assembly location. The probe fuel is exactly the same as the real one, except the pressure taps and the embedded pressure conduits for measuring the pressure drop. First, hydraulic experiments were conducted to find out the pressure drop dependency on the flow rate of the probe fuel in a single fuel assembly test loop. Three correlations between the pressure drop and flow rate, which considers the water temperature effect, were derived from the measurement data of the hydraulic experiments. Using the probe fuel, the flow rates of all fuel assembly locations in the research reactor core were obtained from the measured pressure drop of the probe fuel using the correlations. The investigation of the core flow distribution in the downward forced-cooled research reactor was performed under a nominal flow condition. The flow rate measurements at each fuel assembly location were conducted for two vertical control absorber rod (CAR) positions. The measurement results showed that the primary coolant flow in the reactor core was distributed evenly with a small deviation of −2.9%~+2.3%, even though the CAR position changed. However, the ratio of the core flow and the bypass flow in the reactor was changed slightly with the position of the CARs, which seemed to be due to the changes in the flow resistance depending on the CARs’ position. In addition, the total flow rate of the primary cooling system (PCS) also increased a little when the condition of the CARs was fully withdrawn.

Shape optimization of segmental porous baffles for enhanced thermo-hydraulic performance of shell-and-tube heat exchanger

This study presents the development and evaluation of a novel shell-and-tube heat exchanger (STHX) design with segmental porous baffles. Computational fluid dynamics (CFD) in combination with machine learning tools are utilized to investigate the thermo-hydraulic impacts of segmental porous baffles on shell side flow of a STHX. Three geometric parameters (number of baffles, baffle angle, and baffle thickness) of these baffles, which are placed inside the STHX, are selected to perform the parametric study and multi-objective optimization. Higher number of baffles are beneficial to increase the rate of heat exchange; however, it would escalate the pressure drop considerably. Results also show that baffles angle plays a critical role on the performance of a STHX. An artificial neural network (ANN) is trained to predict the system’s performance. As lowering the pressure drop and increasing the heat transfer are the two main objectives in STHX, a multi-objective optimization study is conducted. Different decision-making algorithms are also applied to find the best alternative among the Pareto frontier points. Results of optimization show that a STHX with 10 porous baffles, baffle angle of 111.9, and baffle thickness of 16.69 mm would be the best geometrical configuration which results in a heat transfer rate of 523.81 kW while the pressure drop of the shell side flow would be 48.87 kPa. With this novel design, it is also possible to improve both pressure drop and heat transfer rate of STHX, simultaneously. A particular configuration of the introduced STHX could reduce the pressure drop by 61.3% while heat transfer enhances by 11.15% simultaneously.

Experimental studies on gas dissipation during the coring process of shale

A series of experiments were performed to study the influence of initial pressures and pressure drop rates on the amount of lost gas during the coring process. The change laws of cumulative gas production and gas production rate were investigated. The proportion changes of lost gas, desorbed gas, and residual gas were analyzed. The results show that the cumulative gas production can be divided into three stages. There is a step with a relatively stable gas production rate in the gas production rate-time curve. The proportional change curves of the lost gas and desorbed gas have the same turning point.

Effects of pressure drop rate and CO2 content on the foaming behavior of newly developed high-melt-strength polypropylene in continuous extrusion

We report systematic studies on the foamability of our novel high-melt-strength long-chain branched polypropylene under supercritical CO2. Continuous foaming experiments were conducted using a tandem extrusion system and a set of filamentary dies with similar pressure drops but different pressure drop rates. The foam expansion was controlled by varying the temperature at the die exit. Under identical CO2 loadings, the expansion ratio plotted as a function of die temperature exhibited similar shapes across multiple pressure drop rates. However, the shape of the curve varied across different amounts of CO2, under which the highest achievable expansion ratio occurred at a lower die temperature with increasing CO2 content. The cell density displayed strong dependence on both the pressure drop rate and the amount of dissolved CO2. The effect of the latter became more apparent at lower pressure drop rates. The average cell size decreased with increasing CO2 loading but generally showed weak dependence on pressure drop rate except at the highest value.

Numerical and experimental study for assessment the effect of baffles in a grooved cavity

The present study is concentrated on the effect of using baffles (as abstraction means) in a cavity to enhance the heat transfer. For this purpose, an experimental and numerical study was carried out. In the experimental study, a test rig consists of a groove rectangular duct and square baffle at three different positions at the top wall with a constant heat flux applied at the bottom wall was built up and used. In the numerical study, mesh generation and finite volume analysis were performed using Ansys. 18 with (k-ε Relazabel) turbulent model to calculate the pressure drop, temperature, and heat transfer rate. The study was concentrated on the effect of baffle position, and number for the range of Reynolds number (4000-16000) and Grashof’s number between (107-108) using air with (Pr=0.7) as a working fluid. The results show that inserting a square baffle at the right position of the cavity leads to increasing of Nusselt number by (73%) comparing to that cavity with no baffles and (60%), (67%) with that at left and center position for the baffle. Comparing numerical and experimental shows a good agreement between them with a maximum deviation (12%), also a close agreement notice when comparing the present results with some of the previous works.

Design and Analysis of double- stacked Heat Exchanger for Brewery Application

A heat exchanger is a device intensively used for enhancing the transfer of heat energy between two or more working fluids at different temperature, which are in thermal contact. The optimal design and efficient operation of heat exchanger and heat transfer network are of a great significance in any of the process industry. The heat transfer efficiency depends on both design of heat exchanger and property of working fluid. From various types of heat exchanger, the double stacked shell and tube heat exchanger with straight tube and single pass is to be under study. Here the redesign of heat exchanger takes place with the key objectives of optimizing the pressure drop, optimizing the heat transfer rate and reducing the saddle support weight used for cooling purpose in brewery application. The design calculations are carried out using the Kerns and Bell Delwar method and other important parameters dealing with material selection and geometries are also taken into consideration. FEA analysis for optimizing the saddle support weight is carried out using Dassault systeme’s Solidworks while the CFD analysis for optimizing pressure drop and heat transfer rate is carried out using Dassault systeme’s Solidworks analysis software and the design and working of Shell and tube heat exchanger is determined in terms of variables such as pressure ,temperature ,mass flow rate ,flow rate ,energy input output that are of particular interest in Shell and tube heat exchanger analysis.

Transitional turbulent flow in a stenosed coronary artery with a physiological pulsatile flow.

The turbulence in the blood flow, caused by plaque deposition on the arterial wall, increases by the combined effect of the complex plaque geometries and the pulsatile blood flow. The correlation between the plaque geometry, the pulsatile inlet flow and the induced turbulence in a constricted artery is investigated in this study. Pressure drop, flow velocity and wall shear stress are determined for stenosed coronary artery models with three different degrees of asymmetric stenosis and for different heart working conditions. A Computational Fluid Dynamics model, validated against experimental data published in the literature, was developed to simulate the blood pulsatile flow inside a stenosed coronary artery model. The transitional flow behaviour was quantified by investigation of the changes in the turbulence kinetic energy. It was shown that the separation starts from the side of the asymmetric stenosis and spreads to its opposite side further downstream. The results suggest that there is a high risk of the formation of a secondary stenosis at a downstream distance equal to 10 times of the artery diameter at the side and bottom regions of the first stenosis due to the existence of the recirculation zones and low shear stresses. Finally, a stenosed patient-specific coronary artery model was employed to illustrate the applicability of the obtained results for real geometry models. The results of this study provide a good prediction of pressure drop and blood flow rate, which can be applied in the investigation of the heart muscle workout and the required heart power.

A modified resistance model for simulating baffle arrangement impacts on cross-flow microfiltration performance for oily wastewater

As a principal problem in the microfiltration processes, cake formation and concentration polarization phenomena cause permeate flux reduction. In the industrial scale, baffle as a turbulence promoter is an efficient method to decrease the fouling phenomenon. In the current study, eleven baffle arrangements in the feed channel were considered for an oily wastewater emulsion. The baffles with four general configurations of wall baffle, central baffle, baffles installed near the membrane surface, and a combination of them are used. The effects of baffle arrangements on turbulent kinetic energy, turbulent dissipation rate, pressure drop, and shear rate, and oil concentration on the membrane surface are examined under steady-state conditions. A modified model of total resistance is proposed to predict the baffle impacts on the CP and cake layer thicknesses and decrease the computational time. The predicted values are compared against experimental data and the absolute relative error is decreased from 6.54 % to 0.03 % by applying the modified resistance model. As the main results, the baffles installed near the membrane surface are more efficient to separate oil from oil-in-water emulsion but it may be caused some problems at higher processing times and the central baffles are recommended for the industrial applications.

Dynamic modeling and prediction of wax deposition thickness in crude oil pipelines

This paper investigates wax deposition as one of the major problems encountered in oil and gas pipelines with a potential environmental damage and with huge financial implications. A molecular diffusion and aging mechanism model by Fick’s law is applied here to better predict wax deposition thickness in crude oil pipelines. Through theoretical derivation and numerical simulation, the diffusion rate into the deposit gel has been modified by modifying the deposit layer temperature to accommodate effect of flow velocity. Findings show that the wax deposit is not uniformly distributed along the pipe length. Data were analyzed based on impact changing oil inlet temperature, volumetric flow rate, and high viscosity using MATLAB software/Simulator. On validation series model convergence was found to perform better with reasonable agreement when compared with experimental data. The result of prediction can be used to determine other parameters in the pipe line such as effective diameter, actual pressure drop and volumetric flow rate in through the pipe.

Thermo-hydraulic characteristics of radiator with various shape nanoparticle-based ternary hybrid nanofluid

Water-based ternary hybrid nanofluid with various shape nanoparticles, i.e., spherical (Al2O3), cylindrical (CNT), and platelet (Graphene) as a new radiator coolant has been investigated in the present analysis. Effect of thermo-hydraulic (pressure drop and heat transfer rate) performance along with exergetic analysis (irreversibility, entropy generation, exergy loss) on ternary hybrid nanofluid vol. concentrations, coolant flow rate, and frontal air velocity has been considered. Furthermore, the XRD and SEM morphology analysis have been conducted for 1% vol. fraction of ternary hybrid nanofluid. The comparative theoretical analysis revealed that the change in ternary hybrid concentrations play an important role in thermal performance due to its shape configuration and 18.45%, 6.3% increment in the heat transfer rate, the second law of efficiency respectively, are observed for 1%–3% vol. fractions range. The irreversibility of the system increases with the application of ternary hybrid nanofluid on coolant flow rate and frontal air velocity. However, a 42.45% increase in irreversibility is observed for a change in ternary hybrid concentrations within the range of 1%–3%. Change in entropy for air is higher compared to the coolant entropy change and results in an increment of 27.27% in entropy change for ternary hybrid nanofluid. Similarly, an increase in air velocity also has the least effect on fan power. Thus, the particle shape in ternary hybrid nanofluids has a significant impact, and its application is more effective in enhancing the thermo-hydraulic performance for an automotive cooling system.

The influence of turbulator on heat transfer and exergy drop of nanofluid in heat exchangers

In current investigation, tape is used to augment pressure drop and heat rate inside heat exchangers in existence of nanofluid. To do this, the three-dimensional model of the twisted tape is chosen for our investigation. This study dedicated on the heat transfer intensifications when significant parameters such as pitching ratio, height ratio and inlet velocity are changed. In order to simulate this model, computational fluid dynamic method with the simple algorithm is applied with k–e (RNG) model for the modeling of the non-laminar flow through the tube due to the presence of the turbulator. Obtained results show a reasonable agreement with experimental data. Our results show that the efficiency of the H2O-CuO nanofluid considerably increases as the Reynolds number augmented in the tube. Moreover, the rate of exergy declines (more than 35%) as the height ratio increased from 0.3 to 0.5.