Experimental Results Of Pressure Drop Research Articles

Comparison Between Numerical and an Experimental Results of Pressure Drop in a Perforated Horizontal Wellbore with a 90° Perforations Phasing

Comparison Between Numerical and an Experimental Results of Pressure Drop in a Perforated Horizontal Wellbore with a 90° Perforations Phasing

Experimental Characterization of an Additively Manufactured Inconel 718 Heat Exchanger for High-Temperature Applications

This work presents the experimental results of a novel, air-to-air, additively manufactured manifold-microchannel heat exchanger with straight fins on both sides. The heat exchanger was made of Inconel 718 using a direct metal laser sintering technique. The overall core size of the heat exchanger was 94 mm × 87.6 mm × 94.4 mm, with a fin thickness of 0.220 mm on both the hot and cold sides. The heat exchanger was tested with pressurized nitrogen gas at 300 °C and 340 kPa for the hot side, while air at an ambient condition was used for the cold side. An overall heat transfer of 276 W/m2K was obtained for Reynolds number values of 132 and 79 for the cold and hot sides, respectively. A gravimetric heat transfer density (Q/m∆T) of 4.7–6.7 W/kgK and a volumetric heat transfer density (Q/V∆T) of 6.9–9.8 kW/m3K were recorded for this heat exchanger with a coefficient of performance value that varied from 42 to 52 over the operating conditions studied here. The experimental pressure drop results were within 10% of the numerical values, while the corresponding heat transfer results were within 17% of the numerical results, mainly due to imperfections in the fabrication process. Despite this penalty, the performance of the tested heat exchanger was superior to the conventional plate-fin heat exchangers: more than 60% of improvements in both gravimetric and volumetric heat transfer densities were recorded for the entire range of experimental data.

A hybrid multiphase model accounting for particle agglomeration for coarse-grid simulation of dense solid flow inside large-scale cyclones

A hybrid multiphase model (Dense Discrete Phase Model, DDPM) coupled with an agglomeration model and a sub-grid drag model was developed for simulation of industrial-scale cyclones with high solid loading. The model is validated by experimental results of pressure drop and separation efficiency from a pilot-scale cyclone with a diameter of 1.6 m. Key trends such as improvement in separation efficiency and reduction in pressure drop of cyclone due to an increase in particle load are well captured by the model. It is concluded that including the agglomeration model is crucial in particular in cases involving very fine particles (d < 15 μm) for accurate predictions of pressure drop and separation efficiency, while using the sub-grid drag modification improves the prediction of separation efficiency.

Computational Fluid Dynamics Modelling and Experimental Study on Pressure drop through Vertical Packed Clay Composite Pellets

The importance of computational fluid dynamics in the field of packed bed medium is acceptable due to the high-end processor power availability. The studies of the literature have presented the feasibility of CFD as an advanced practical tool for estimating the pressure drop through the packed porous medium. In this work a CFD model was evolved to simulate the pressure drop through vertical clay pellets packed bed by using CFX analysis. Experiments are conducted to measure the pressure drop across vertical static clay composite pellets bed. The maximum deviation between CFD analysis and experimental results for pressure drop through 500 mm bed height is 13%.

Numerical investigation of zinc tailings slurry flow field in a horizontal pipeline

Thispaperreportsthefindingsofnumericalinvestigationofdenseparticulateslurryflowfieldinaslurrypipelinewith an objective of examining erosive wear. Parametric study with velocities 2 m/s, 2.75 m/s and 3.5 m/s, and volumetric concentration of 4% and 26% were carried out on a pipeline of nominal inside diameter 105 mm. The range of volumetric concentration was chosen to ascertain the flow field characteristics for low to high particle loading. All the simulations have been computationally performed using ANSYS-FLUENT. The dense particulate slurry is modelled using Eulerian-Eulerian approach while finite volume method (FVM) is employed as the numerical method. Mesh refinement study and validation with experimental results for pressure drop have been reported. Solids concentration and velocity profiles show dependence on flow velocity and inlet average concentration. The distribution of solids concentration and its dependence on the bulk flow velocity qualitatively indicates the regions of relatively higher erosion wear.

Hydrodynamic study and particulate matter removal in a self priming venturi scrubber

Fly ash is the fine particulate matter identified as environmental pollutant emitted from thermal power station. Self priming venturi scrubber is now-a-days getting importance for its high performance efficiency in case of nuclear power plant accident. Therefore, the present paper focuses on the control of fly ash particulate matter from the air using self priming venturi scrubber in both the condition, submerged and non submerged. Detailed investigation on the pressure drop inside the venturi scrubber and scrubbing of particulate matter has been discussed in the present study. It has been found from the experiment that the maximum pressure drop is observed at highest throat gas velocity of 72 m/s, water level height of 0.77 m. Maximum removal efficiency of fly ash, 99.89% is obtained at throat gas velocity of 60 m/s, water level height of 0.77 m with fly ash inlet concentration of 0.3 x10 −3 kg/Nm 3 in submerged condition. Furthermore, empirical model has been developed to validate the experimental results of pressure drop and removal efficiency and compared with the existing mathematical model. • Separation of particle in self priming venturi scrubber using water has been done. • Hydrodynamics study is also investigated in terms of pressure drop. • Experiments carried out in both conditions-submerged and non-submerged. • Maximum fly ash removal efficiency is obtained as 99.89% in submerged condition. • Efficiency is a function of gas velocity, fly ash concentration and water level.

Experimental study on two-phase flow pressure drop during ethanol–water vapor mixture condensation in microchannels

Ethanol-water vapor mixtures condensation shows different flow patterns in microchannels due to the equivalent surface free energy differences. The transition point of streak flow pattern was introduced in the paper which was found closely related to the frictional pressure drop of ethanol–water vapor mixtures condensation flow in microchannels. Characteristics of two-phase pressure drop for ethanol–water vapor mixtures condensation flow in silicon microchannels of streak and smooth annular flow pattern were investigated. Four types of multi-port trapezoidal and triangular microchannels with hydraulic diameter in the range of 126–155 μm were employed. The pressure drop was determined under steam mass flux between 259.2 and 504.8 kg m−2 s−1 when the inlet ethanol weight concentration varied from 1% to 60%. The experimental pressure drop results were compared with existing correlations of flow condensation. The transition point basing on the streak flow pattern of binary vapor condensation was proposed to replace the traditional Reynolds number criterion of the laminar flow state to turbulent flow state for the frictional factor and the C parameter for Kim and Mudawar’s universal pressure drop model, which is in good agreement with the results the experiment results.

CT scanning of membrane feed spacers – Impact of spacer model accuracy on hydrodynamic and solute transport modeling in membrane feed channels

This study evaluated the impact of precise representation of spacer geometry on numerical simulations of hydrodynamics and solute transport in feed channels of membrane processes. Three levels of increasing geometry accuracy were assessed: i) cylindrical filaments, ii) filaments with circular sections of variable diameter based on microscopic measurements, and iii) geometries obtained from X-ray computed tomography (CT scans) in three resolutions (22 µm, 11 µm, and 5.5 µm). The three-dimensional CT scans revealed quasi-elliptic, not circular, cross-sections of the filaments. Microscopic measurements fail to account for this ellipticity, resulting in overestimation of pressure drop calculated at industry-typical average velocities (0.07–0.15 m s−1) by a factor of 1.8 compared to CT-based geometries. On the other hand, the cylindrical spacer filaments representation overestimates concentration polarization at the membrane surface compared to CT-based geometries. Experimental results of pressure drop and particle deposition were in close agreement with simulations using CT scanned geometries. This work demonstrates that modeling results depend significantly on the spacer geometry accuracy. Within the investigated CT scan accuracies 20 µm was found sufficient for modeling hydrodynamics and solute transport in spacer-filled feed channels. The results may be useful for reliable investigation and development of novel spacer geometries.

Mathematical spacer grid models for two phase flow

The fuel rods of nuclear power plants covering Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) cores are supported by spacer grids. Even though spacer grids add to the pressure loss in the reactor core, spacer grids have several benefits in LWRs. Some of these benefits are: (i) increasing the turbulence at the bottom of the reactor core for better heat transfer in single phase region of the LWRs, (ii) improving the departure nucleate boiling ratio results for PWRs, and (iii) improving critical power ratio (CPR) values by increasing the thickness of film in annular flow regime in the top section of the reactor core of BWRs. Several mathematical models have been developed for pressure loss across the grid spacer. Almost all of them significantly depend on Reynolds Number. Spacer designs have evolved (incorporating mixing vanes, springs, dimples, etc), resulting in the complexity of the analysis across the grid, all the models have been compared not only theoretically but also quantitatively. For the quantitative comparisons, this work compares the results of mathematical spacer models with experimental data of BWR Full Size Fine Mesh Bundle Tests (BFBT). The experimental data of BFBT provides very detailed experimental results for pressure drop by using several different boundary condition and detailed pressure drop measurements. Since one CT-scanner was used at the bundle exit and three X-ray densitometers were used for the chordal average void distribution at different elevations to generate the BFBT results, detailed two phase parameters have been measured in BFBT database. Detailed experimental data of BFBT was used for analyzing two phase flow mathematical models of spacer grid for various boundary conditions of BWR in this paper. It was observed and discussed that pressure drop values due to spacer models can be significantly different.

Mathematical spacer grid models for single phase flow

The fuel rods in pressurized water reactor (PWR) and boiling water reactor (BWR) cores are supported by spacer grids. Even though spacer grids add to pressure loss in the reactor core, spacer grids have several benefits in light water reactors (LWRs). Some of these benefits are: (i) increasing turbulence at the bottom of the reactor core for better heat transfer in single phase region of LWRs, (ii) improving departure nucleate boiling ratio results for PWRs, and (iii) improving critical power ratio (CPR) values by increasing the thickness of film in annular flow regime in the top section of the reactor core of BWRs. Several mathematical models have been developed for single and two phase pressure loss across the grid spacer. Almost all of them significantly depend on Reynolds Number. Spacer designs have evolved (incorporating mixing vanes, springs, dimples, etc), resulting in complexity of the analysis across the grid. The models have been compared not only theoretically but also quantitatively. For the quantitative comparisons, this work compares results of mathematical spacer models with experimental data of BWR Full Size Fine Mesh Bundle Tests (BFBT). The experimental data of BFBT provides very detailed experimental results for pressure drop by using several different boundary condition and detailed pressure drop measurements. Two bundle types of BFBT, the current 8×8 type and the high burn-up 8×8 type, were simulated. There are two also types of spacers in the BFBT program – ferrule type and grid type. Therefore, the experimental data of BFBT used a wide range of boundary conditions of BWRs. This paper analyzes mathematical models of spacer grids for a portion of available data. It was observed and discussed that pressure drop values due to spacer models can be significantly different for single phase flow.

Forced-convective heat-transfer coefficient and pressure drop of water-based nanofluids in a horizontal pipe

In this paper the heat transfer performance of Al2O3, SiO2 and multi-walled CNTs (MWCNTs) in a closed loop were investigated. Heat transfer coefficient and pressure drop were measured in a horizontal thermal-insulated test-section. Special care was taken in the loop calibration and the estimation of measurement uncertainties. The results show that the Gnielinski correlation can be used to predict the turbulent heat transfer coefficient as long as the proper experimental values for the thermophysical properties of each nanofluid are used. Also, the Colebrook–White correlation for the friction factor showed good agreement with the experimental results for pressure drop. The nanofluids showed an increased heat transfer coefficient with respect to that of water on a constant Reynolds number basis, but a reduced performance when compared on a constant pumping power basis. Note that some authors treat CNTs as nanofluids because one of their dimensions is in the nanoscale, but strictly speaking this dimension is not the one that is actually contributing to the changes in the thermal properties of the mixture. We include them in our analysis to demonstrate that this kind of suspension also follows conventional correlations.

Percutaneous double lumen cannula for right ventricle assist device system: A computational fluid dynamics study

ObjectivesOur goal is to develop a double lumen cannula (DLC) for a percutaneous right ventricular assist device (pRVAD) in order to eliminate two open chest surgeries for RVAD installation and removal. The objective of this study was to evaluate the performance, flow pattern, blood hemolysis, and thrombosis potential of the pRVAD DLC. MethodsComputational fluid dynamics (CFD), using the finite volume method, was performed on the pRVAD DLC. For Reynolds numbers <4000, the laminar model was used to describe the blood flow behavior, while shear-stress transport k–ω model was used for Reynolds numbers >4000. Bench testing with a 27Fr prototype was performed to validate the CFD calculations. ResultsThere was <1.3% difference between the CFD and experimental pressure drop results. The Lagrangian approach revealed a low index of hemolysis (0.012% in drainage lumen and 0.0073% in infusion lumen) at 5l/min flow rate. Blood stagnancy and recirculation regions were found in the CFD analysis, indicating a potential risk for thrombosis. ConclusionsThe pRVAD DLC can handle up to 5l/min flow with limited potential hemolysis. Further modification of the pRVAD DLC is needed to address blood stagnancy and recirculation.

Two-phase pressure drop during upward cross flow in triangular tube bundle

This paper presents experimental results for pressure drop during air-water upward two-phase flow across horizontal triangular tube bundle. It is estimated that more than half of shell-and-tube heat exchangers in industry operate under two-phase flow conditions in the shell side. However the number of research and publications focused on external flow is considerably reduced when compared to intube flow. This study addresses experimental results for pressure drop during external flow of air and water mixtures across a triangular tube bundle counting with 19 mm OD tubes and 24 mm transverse pitch, for superficial velocities up to 0.553 and 10 m/s for water and air, respectively. For reduced mass velocities, the gravitational pressure drop parcel is dominant, consequently the adoption of an appropriate methodology for void fraction estimative is essential for accurate estimative of the gravitational pressure drop parcel. The experimental results are compared with predictive methods available in the open literature, and an analysis of this comparison is presented.

Heterogeneous ice slurry flow and concentration distribution in horizontal pipes

Ice slurry is an energy-intensive solid–liquid mixture fluid which may play an important role in various cooling purposes. Knowing detailed flow information is important from the system design point of view. However, the heterogeneous ice slurry flow makes it difficult to be quantified due to the complex two phase flow characteristic. The present study applies a Mixture computational fluid dynamics (CFD) model based on different rheological behavior to characterize the heterogeneous ice slurry flow. The Mixture CFD model was firstly validated by three different experiments. Then the validated Mixture CFD model was applied to solve the ice slurry isothermal flow by considering the rheological behavior piecewise. Finally, the numerical solutions have displayed the coupled flow information, such as slurry velocity, ice particle concentration and pressure drop distribution. The results show that, the ice slurry flow distribution will appear varying degree of asymmetry under different operating conditions. The rheological behavior will be affected by the asymmetric flow distributions. When mean flow velocity is high, Thomas equation can be appropriate for describing ice slurry viscosity. While with the decreasing of mean flow velocity, the ice slurry behaves Bingham rheology. As compared with experimental pressure drop results, the relative errors of numerical computation are almost within ±15%. The Mixture CFD model is validated to be an effective model for describing heterogeneous ice slurry flow and could supply plentiful flow information.

Two-phase frictional pressure drops in U-bends and contiguous straight tubes for different refrigerants, orientations, tube, and bend diameters: Part 1. Experimental results (RP-1444)

Over the years, much research has been conducted on two-phase flows in straight tubes because these tend, in length, to be predominant in two-phase systems. However, two-phase heat exchangers can also have singularity elements, where the most common type is typically a U-bend. The importance of these elements on the design of a system is that their frictional pressure gradients are much higher than those occurring in straight tubes. Therefore, in this study, pressure drop measurements were made for U-bends and their contiguous straight tubes with two-phase refrigerants. The experiments were made with R410A and R134a at two saturation temperatures (5°C and 10°C [41°F and 50°F]) flowing at three mass fluxes (150, 300, and 500 kg s−1m−2 [110.6·103, 221.2·103, and 368.7·103 lb h−1 ft−2]) inside five different test sections with three different internal diameters (13.4, 10.7, and 7.8 mm [0.527, 0.421, and 0.307 in.]) and five different bend diameters (66.1, 54.8, 38.1, 31.7, and 24.8 mm [2.602, 2.157, 1.5, 1.248, and 0.976 in.]) in three different orientations (horizontal, vertical upflow, and vertical downflow) with vapor qualities ranging from 0.05 to 0.95. The first part of this article focuses on the experimental pressure drop results, while the second part presents a new flow pattern based frictional pressure drop model for U-bends and an updated version of the straight tube frictional pressure drop model of Moreno Quibén and Thome (2007b).

Experimental investigation of ice slurry flow pressure drop in horizontal tubes

Pressure drop behaviour of ice slurry based on ethanol–water mixture in circular horizontal tubes has been experimentally investigated. The secondary fluid was prepared by mixing ethyl alcohol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature −4.4 °C). The pressure drop tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 30% depending on test conditions. Results from flow tests reveal much higher pressure drop for higher ice concentrations and higher velocities in comparison to the single phase flow. However for ice concentrations of 15% and higher, certain velocity exists at which ice slurry pressure drop is same or even lower than for single phase flow. It seems that higher ice concentration delay flow pattern transition moment (from laminar to turbulent) toward higher velocities. In addition experimental results for pressure drop were compared to the analytical results, based on Poiseulle and Buckingham–Reiner models for laminar flow, Blasius, Darby and Melson, Dodge and Metzner, Steffe and Tomita for turbulent region and general correlation of Kitanovski which is valid for both flow regimes. For laminar flow and low buoyancy numbers Buckingham–Reiner method gives good agreement with experimental results while for turbulent flow best fit is provided with Dodge–Metzner and Tomita methods. Furthermore, for transport purposes it has been shown that ice mass fraction of 20% offers best ratio of ice slurry transport capability and required pumping power.

Effect of developing flow and thermal regime on momentum and heat transfer in micro-scale heat sink

A developing micro-channel heat transfer and fluid flow has been investigated experimentally in rectangular micro-channels of D h = 440 μm, having water as a working fluid. Infrared technique was used to design and built a micro-channel test section that incorporate internal fluid temperature measurements. The new method that provides information about the fluid temperature distribution inside the channel and provides validation for the methods used to determine the local and average Nusselt numbers. The experimental results have been compared with theoretical predictions from the literature and results obtained by numerical modeling of the present experiment. The experimental results of pressure drop and heat transfer confirm that including the entrance effects, the conventional theory is applicable for water flow through micro-channels. These results differ from the conclusions of several researches. It was shown that data presented by some researches can be due to entrance effects. The present results highlight the importance of accounting for common phenomena that are often negligible for standard flows such as accounting for profile of inlet velocity, axial heat conduction, effect of the design inlet and outlet manifolds. This paper, to the best of knowledge, is the first presentation on the method of the bulk fluid temperature measurements along micro-channel using IR technique, and calculation of the local heat transfer coefficient based on the local heat flux and the local temperature difference between the heated wall and the bulk fluid temperature.

Pressure drop characteristics of poly(high internal phase emulsion) monoliths

Today, monoliths are well-accepted chromatographic stationary phases due to several advantageous properties in comparison with conventional chromatographic supports. A number of different types of monoliths have already been described, among them recently a poly(high internal phase emulsion) (PolyHIPE) type of chromatographic monoliths. Due to their particular structure, we investigated the possibility of implementing different mathematical models to predict pressure drop on PolyHIPE monoliths. It was found that the experimental results of pressure drop on PolyHIPE monoliths can best be described by employing the representative unit cell (RUC) model, which was originally derived for the prediction of pressure drop on catalytic foams. Models intended for the description of particulate beds and silica monoliths were not as accurate. The results of this study indicate that the PolyHIPE structure under given experimental condition is, from a hydrodynamic point of view, to some extent similar to foam structures, though any extrapolation of these results may not provide useful predictions of pressure versus flow relations and further experiments are required.

Carbon-steel corrosion in multiphase slug flow and CO 2

Hydrocarbon multiphase flow may exhibit various geometric configurations or flow patterns. One of these flow patterns is known as multiphase slug flow. If CO 2 is present in hydrocarbons, the steel pipelines can be corroded as this process is probably enhanced by slug flow turbulence. A hydrodynamic circuit was built to study the CO 2 corrosion rates under different slug flow conditions. The experimental results show how the corrosion rate of a carbon-steel electrode varies according to the flow turbulence. The higher slug frequency used in this study was 80 slugs/min. Experimental results for pressure drop and slug length are in agreement with the Dukler and Hubbard [A model for gas–liquid slug flow in horizontal and near horizontal tubes, Ind. Eng. Chem. Fundam. 14 (1975) 337–347] multiphase flow model. Furthermore, the experimental slug frequencies are well correlated by the Shell and Gregory [Correlation of the liquid volume fraction in the slug for horizontal gas–liquid slug flow. Int. J. Multiphase Flow 4 (1978) 33–39] equations in horizontal pipes.

The Rotary Trickle-Bed Reactor– A New Reactor Concept for Biological Gas Purification

A new type of reactor employed to the biological gas purification is presented. The avoidance of clogging in the carrier packing is achieved by i) the use of a structured, rotating carrier packing, ii) a definite liquid irrigation regime during start-up, operation and clean-up time phases, iii) an on-line determination and control of the fixed biofilm mass. A uniform biofilm thickness is generated by an optimized liquid irrigation of the carrier packing with spray nozzles. The detachment of the fixed biomass is accomplished by liquid shear forces generated with jet nozzles. The time-scheduled operation regime of the reactor is founded on the on-line quantification of the immobilized biomass, which results in a new quality of process governing of biotrickling reactors applied to gas purification. This is proved by the experimental results of pressure drop, dynamic liquid holdup as well as the volumetric degradation rates. The degradation of styrene was investigated in laboratory and field experiments showing a maximal volumetric degradation rate of 150 g m–3 h–1 at a pollutant load of 200 g m–3 h–1. The feasibility of this reactor prototype is demonstrated by employing it to the elimination of industrial waste gas.