Pressure Drop Measurements Research Articles

Extensional rheometry of mobile fluids. Part II: Comparison between the uniaxial, planar, and biaxial extensional rheology of dilute polymer solutions using numerically optimized stagnation point microfluidic devices

Part I of this paper [Haward et al., J. Rheol. 67, 995–1009 (2023)] presents a three-dimensional microfluidic device (the optimized uniaxial and biaxial extensional rheometer, OUBER) for generating near-homogeneous uniaxial and biaxial elongational flows. Here, in Part II, the OUBER device is employed to examine the uniaxial and biaxial extensional rheology of model dilute polymer solutions, compared with measurements made under planar extension in the optimized-shape cross-slot extensional rheometer [OSCER, Haward et al. Phys. Rev. Lett. 109, 128301 (2012)]. In each case, micro-particle image velocimetry is used to measure the extension rate as a function of the imposed flow conditions, and excess pressure drop measurements enable estimation of the tensile stress difference generated in the fluid via a new analysis based on the macroscopic power balance for flow through each device. Based on this analysis, for the most dilute polymer sample tested, which is “ultradilute”, the extensional viscosity is well described by Peterlin’s finitely extensible nonlinear elastic dumbbell model. In this limit, the biaxial extensional viscosity at high Weissenberg numbers (Wi) is half that of the uniaxial and planar extensional viscosities. At higher polymer concentrations, although the fluids remain dilute, the experimental measurements deviate from the model predictions, which is attributed to the onset of intermolecular interactions as the polymer chains unravel in the extensional flows. Of practical significance (and fundamental interest), elastic instability occurs at a significantly lower Wi in uniaxial extensional flow than in either biaxial or planar extensional flow, thereby limiting the utility of this flow type for extensional viscosity measurement.

Clay-induced permeability decline in sandstone reservoirs: Insights from a coupled NMR-SEM experimental approach

The blockage induced by solid particles transport and deposition is one of the main causes of injectivity decline in geothermal sandstone reservoirs during reinjection. This paper investigates clay-induced clogging mechanisms to provide a better understanding to formation damage problems encountered in geothermal fields. In-depth NMR measurements were carried out during core-flooding experiments where illite clay particles (120 nm) were injected in sand-packed columns. SEM imaging was performed to compare the porous space before and after damage and study the morphology and distribution of the deposited particles in the sand column. Pressure drop measurements and NMR T2 relaxation time distributions revealed that clogging occurs in two stages: surface deposition and pore bridging. This was further confirmed by SEM images showing that pore-blocking illite ribbons were formed in the porous space.

Drag Reduction by Fish-Scale Inspired Transverse Asymmetric Triangular Riblets: Modelling, Preliminary Experimental Analysis and Potential for Fouling Control.

The natural surfaces of many plants and animals provide examples of textures and structures that remain clean despite the presence of environmental fouling contaminants. A biomimetic approach to deciphering the mechanisms used by nature will facilitate the development and application of fouling-resistant surfaces to a range of engineering challenges. This study investigated the mechanism underlying the drag reduction phenomenon that was shown to be responsible for fouling resistance for underwater surfaces. For this purpose, a novel fish-scale-inspired microstructure was shown to exhibit a drag reduction effect similar to that of its natural replica. The primary mechanism through which this occurs is a delayed transition to turbulence. To investigate this mechanism, a Large Eddy simulation was performed at several Reynolds numbers (Re). This analysis demonstrated a peak drag reduction performance of 6.7% at Re = 1750. The numerical data were then experimentally validated through pressure drop measurements performed by means of a custom-built micro-channel. In this case, a peak drag reduction of 4.8% was obtained at Re = 1000. These results suggest a relative agreement between the experimental and numerical data. Taken together, this study advocates that, for the analyzed conditions, drag reduction occurs at low Reynolds numbers. Nonetheless, once flow conditions become more turbulent, the decline in drag reduction performance becomes apparent.

Experimental study of the effect of viscous media on the hydrodynamic characteristics of a rotating packed bed

A simple and robust quantitative approach was proposed to determine liquid entrainment and flooding in rotating packed beds (RPBs), which complements visual observations and pressure drop measurements. The RPB was modified by installing a hydrocyclone at the gas outlet to quantify the amount of liquid ejected. The original technique previously introduced in the literature for air-water systems, was explored using a viscous mixture to determine the flooding onset. This approach eliminates bias in the criteria used to define the onset of liquid entrainment and flooding in RPBs. The method also minimizes inaccuracies introduced by unexplained pressure drops during flooding in RPBs. In the method, flooding occurred when entrainment exceeds 8% of the total liquid inlet flow rate. The study used a water-glycerine mixture with viscosities of 13 and 30 mPa.s and found that the entrainment of viscous liquids in RPBs begins with a small volume of liquid droplets, progressing to moderate volumes of liquid-film entrainment. The quantitative approach used in this study enhances the reliability of fundamental data essential for the design and scale-up of RPBs. This study is an indispensable guide for using RPBs in high-viscosity mass transfer and separation processes.

Experimental Study of an Internally Channeled Tube Heat Exchanger under Turbulent Flow Conditions

In our previous work, an innovative heat exchanger design, the so-called internally channeled tube (ICT), was proposed based on a channels-in-tube principle. The new geometry provides a significantly larger heat transfer area than similar conventional heat exchangers. Furthermore, a three-dimensional numerical model was developed to govern fluid dynamics and heat transfer in the ICT. The focus of the present paper is an experimental investigation of the ICT under turbulent flow conditions. The experimental set-up is presented in detail and the measurement procedure is highlighted. In particular, the maldistribution issue is considered. Measured pressure drop and temperature values are used to validate the numerical model. The deviation between simulated and experimental values is below 6.5% for the pressure drop and below 13% for the heat transfer coefficient.

Characterization of pressure drop through Schwarz-Diamond triply periodic minimal surface porous media

Additive manufacturing (3D printing) is enabling novel porous structures such as triply periodic minimal surfaces (TPMS) that may help improve the efficiency of various applications in chemical engineering. In this work, a range of Schwarz-Diamond TPMS structures were examined experimentally in terms of printability and pressure drop. X-ray computed tomography scans were used to show that the shape of the structures was accurately printed, however a systematic reduction in porosity was observed compared with each designed structure. The pressure drop through the printed structures was measured for Reynolds numbers between 1 and 1000. Pressure drop reduced with increasing porosity and hydraulic diameter but there was no effect of printer type or column diameter on the measured pressure drop. These measurements were used to propose a new pressure drop correlation that can be used to predict the pressure drop for Schwarz-Diamond TPMS structures over a range of porosities and hydraulic diameters.

The effect of inlet velocity, gas temperature and particle size on the performance of double cyclone separator

In this present study, the effect of inlet velocity, gas temperature on pressure drop and the effect of particle size on the collection efficiency under different operating conditions are demonstrated for a double cyclone separator, which mainly consists of a 2D2D and 1D3D cyclone in series arrangement. The experiment of pressure drop measurement for different inlet gas velocities in the range of 11–23 m/sec are conducted and it is observed that the pressure drop increase with an increase in gas velocity, which is also validated with CFD results using RSM model and well-established theoretical models. The numerical simulation is also performed for different gas temperature in the range of 300–1100 K. The prediction shows that the pressure drop decrease gradually with increasing the gas temperature, which also gives a better agreement with empirical correlations. The collection efficiency has been estimated for different particle size in the range of 1–10μmat u = 23 m/sec, by CFD approach. It is noted that the efficiency of single cyclone is very poor for fine particles (<5μm) but adding a 1D3D cyclone in series with a 2D2D cyclone separator, the pressure drop is reduced more and the overall separation efficiency is improved in a comprehensive way.

Effects of velocity on N2 and CO2 foam flow with in-situ capillary pressure measurements in a high-permeability homogeneous sandpack

The effects of velocity and gas type on foam flow through porous media have yet to be completely elucidated. Pressure drop and capillary pressure measurements were made at ambient conditions during a series of foam quality scan experiments in a homogenous sandpack while foam texture was simultaneously visualized. New insights into foam-flow behavior in porous media were discovered. Previously accepted “limiting” capillary pressure theory is challenged by the findings in this work, and the “limiting” terminology is replaced with the word “plateau” to reflect these novel observations. Plateau capillary pressure {(P}_{c}) and transition foam quality were found to increase with velocity. Transition foam quality was found to depend mostly on liquid velocity rather than gas velocity and is physically linked to foam type (continuous vs. discontinuous) and texture (fine vs. coarse). Distinct rheological behaviors also arose in the low- and high-quality foam regimes as a function of velocity. Foam flow was found to be strongly shear thinning in the low-quality regime where foam texture was fine and discontinuous. In the high-quality regime, the rheology was weakly shear thinning to Newtonian for coarsely textured foam and continuous-gas flow respectively. When all other variables were held constant, at ambient conditions, CO2 foam was found to be weaker with also lower capillary pressures than N2 foam and the differences in gas solubility is a likely explanation.

Evolution of porous boundary condition in numerical wave tank

A vertical porous or perforated structure can be considered an effective breakwater due to its efficient use in deep water when compared to conventional breakwaters. The hydrodynamic performance of this breakwater can be evaluated by studying the wave reflection and transmission through it. Various experimental studies in the past have shown the performance characteristics of this structure, but their application is limited due to the required effort, time, and manpower (Rajendra et al., 2017). As an alternative, a numerical model can be advantageous in representing exact situations and providing additional benefits. Therefore, as a preliminary study, the wave reflection and transmission of the vertical perforated breakwater are simulated in a numerical wave tank using a unique approach to defining porous boundary conditions. The numerical wave tank is developed using a finite volume-based FLUNET tool with a viscous-laminar model configuration. However, the porous boundary condition is defined in terms of the inertial resistance coefficient, which was derived from pressure drop measurements taken across the perforated structure during lab experiments. The wave reflection and transmission obtained from the numerical wave tank show good agreement with the experimental data. Interestingly, a closer examination of the flow field in the vicinity of the breakwater indicates partial standing wave formation, which contributes to an increase in wave reflection for a limited case.

Computational fluid dynamics modeling of contaminant transport with adsorption filtration inside planar-shaped air-purifying respirator canister

We performed computational fluid dynamics (CFD) simulations of the contaminant transport with adsorption filtration inside a planar-shaped air-purifying respirator (APR) canister and predicted the breakthrough times of the canisters with various internal shapes. The numerical modeling of the adsorption process based on the backward differentiation formulas, which comprise the implicit method implemented in COMSOL Multiphysics, demonstrated the validity through the simulations of the fixed-bed column breakthrough test. Model parameters were estimated by applying Bayesian inference to the breakthrough test and pressure drop measurement data. Previous CFD studies assessed the filtering efficiency based on the local flow speed and mean air age; this approach replaced adsorption modeling, which is computationally expensive. We tested six planar-shaped APR canisters and observed that the dead zone near the walls in the air age field does not appear in the contaminant transport simulation with adsorption modeling. We identified that the velocity fields inside the filter determined the breakthrough distributions. Further, we confirmed that the breakthrough time was more related to the maximum flow speed inside the filter and less with local mean air age. We demonstrated the importance of simulating contaminant transport with adsorption modeling for the APR canister and reliability of the alternative indices.

Thermal Modeling and Experimental Validation of Mid-Conductor Winding Cooling

A direct cooling method for windings of electrical machines, mid-conductor winding cooling, is studied. Spaces between the wires are utilized as coolant channels, with a liquid being pumped through the winding along the length. These results in the elimination of thermal interface resistances, a high heat transfer area and heat transfer coefficient while maintaining the same cross-sectional area for the copper winding. A thermohydraulic model is made and validated to analyze the heat transfer rates and pressure drop. Validation measurements with a water-glycol mixture as coolant show that the modeled and measured pressure drop correspond within 0.07 bar and the modeled and measured winding temperature within 3 °C. When made relative to the temperature difference between winding and coolant, the deviation is equal to 12%. The validated model is used to analyze the performance when utilizing oil as coolant. For a winding temperature of 180 °C and a pressure drop of 1 bar, using the novel cooling method results in a maximal attainable current density equal to 39.4 A/mm2 which is 41% higher than that attainable with spray end winding cooling.

Predictive modelling approach for cottonseed plug velocity applying a circuit theory analogy

In this study, a circuit theory analogy was used to investigate plug behaviour in dense phase pneumatic conveying of cottonseeeds. It was found that the time series aeration/deaeration pressure drop of a fixed bed exhibits exponential behaviour, similar to the charging/discharging of a capacitor in a circuit. Using this analogy, the pressure drop below transition superficial air velocity was considered equivalent to the potential voltage across a capacitor over time. By extending this analogy beyond transition superficial air, a potential pressure drop was introduced and found to separate from the measured pressure drop at the moment the plug moves. It was demonstrated that the difference between the potential and measured pressure drop can be scaled to the plug velocity, indicating a linear relationship between these variables. This approach provides a novel method for understanding and predicting plug behaviour in pneumatic conveying, which may have practical applications for various types of other materials.

Impedance models for single and two degree of freedom linings with an improved data base and local non-linearity

Previously developed predictive models for impedance of single-degree-of-freedom and two-degree-of-freedom acoustic linings driven by a broad band acoustic source are reexamined. Two issues are addressed, the first being improvement of the conventional perforate face sheet impedance model. Data correlations based on flow bench measurements of steady flow pressure drop are reevaluated with emphasis on low flow velocity to improve the consistency of the prediction of linear resistance. In addition, for two-degree-of-freedom linings, face sheet mass reactance is modified to account for the presence of the septum. The second issue addresses the implication that for a non-linear lining, with impedance a function of the local sound pressure level, the installed performance of the lining depends on the local impedance, as opposed to impedance based on the source sound pressure level. This is investigated in the benchmarking of the impedance models by comparison of the acoustic transfer function predicted by a propagation code with the imbedded impedance model and transfer function measurements made in a grazing flow duct test facility. The propagation code is extended to make the non-linear behavior of the lining model dependent on the local acoustic spectrum, introducing an additional level of non-linearity and an iterative application of the propagation code. A principal conclusion is that with no grazing flow both the lining model and grazing flow duct transfer function measurements show a significant effect of local variation of the acoustic spectrum. With increasing grazing flow Mach number, this effect is reduced and effectively disappears at the highest Mach number. With increasing grazing flow Mach number the grazing flow contribution to face sheet resistance dominates and tends to mask the non-linear behavior of the component of resistance not related to grazing flow.

Data-Driven Virtual Viscosity Meter Augments Inline, Laboratory Measurements

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211393, “Introducing Data-Driven Virtual Viscosity Measurements,” by Volodmir Karpan, Shell, and Samya Al Farsi and Hanaa Al Sulaimani, SPE, Petroleum Development Oman, et al. The paper has not been peer reviewed. _ For polymer-based chemical flooding projects, controlling the viscosity of the injected polymer solution is critical because polymer cost is one of the more significant elements in project economics. The polymer viscosity is measured routinely in the laboratory using fluid samples taken manually at different sampling points. In the case of large-scale projects, however, such viscosity monitoring becomes time-consuming and requires a dedicated field staff. The complete paper introduces a data-driven virtual viscosity meter (VVM) as a tool to augment inline and laboratory viscosity measurements. Introduction In field conditions, proven ways to monitor polymer viscosity of the injected solution include laboratory measurements using injector wellhead samples and inline measurements using a viscometer. In the former, injected chemical solution is sampled regularly to test its viscosity in the laboratory. This is a time- and labor-intensive method with safety and environmental risks during sampling. The latter method is a way to monitor viscosity using inline viscosity-measurement devices. Measuring the viscosity inline reduces the risk of polymer degradation significantly and provides more viscosity data. An inline viscometer uses pressure-drop and flow-rate measurements for the fluid flowing in a bypass line. Pressure drop is measured in the insulated coiled tube, while the flow rate is measured using a Coriolis-type flowmeter. During operation, the polymer solution temperature and pressure drop at a fixed flow rate are measured continuously. The system then calculates the viscosity of the polymer solution passing through the viscometer using the curve extrapolated from the calibration points. Such a viscometer measures a wide range of polymer viscosity and could be used for both high-viscosity and diluted solutions at low and high pressures. Use of inline viscosity measurement, while advantageous in many ways, comes with significant costs. An inline viscometer usually is installed on the foundation in a cabinet to protect it from harsh weather conditions (Fig. 1). Additionally, the injection line upstream of the wellhead must be equipped with a bypass line and drainage system. Maintenance activities could affect the uptime of the inline viscometer. This could become critical under field conditions, where problems with water treatment could translate into plugging of the viscometer filters, leading to erroneous measurements and eventual downtime for cleanup. Such problems grow with the number of devices in operation. Therefore, using a few viscometers is often considered a compromise that comes at the cost of less-effective viscosity monitoring. The authors address a solution to this problem wherein a machine-learning (ML) tool is proposed to augment viscosity measurements by calculating the viscosity using field data for the periods when no viscosity measurements are available.

Pore‐Scale Imaging of Multiphase Flow Fluctuations in Continuum‐Scale Samples

AbstractRepresentative elementary volumes (REVs) are an important concept in studying subsurface multiphase flow at the continuum scale. However, fluctuations in multiphase flow are currently not represented in continuum scale models, and their impact at the REV‐scale is unknown. Previous pore‐scale imaging studies on these fluctuations were limited to small samples with mm‐scale diameters and volumes on the order of ∼0.5 cm3. Here, we image steady‐state co‐injection experiments on a one‐inch diameter core plug sample, with nearly two orders of magnitude larger volume (21 cm3), while maintaining a pore‐scale resolution with X‐ray micro‐computed tomography. This was done for three total flow rates in a series of drainage fractional flow steps. Our observations differ markedly from those reported for mm‐scale samples in two ways: the macroscopic fluid distribution was less ramified at low capillary numbers (Ca) of 10−7; and the volume fraction of intermittency initially increased with increasing Ca (similar to mm‐scale observations), but then decreased at Ca of 10−7. Our results suggest that viscous forces may play a role in the cm‐scale fluid distribution, even at such low Ca, dampening intermittent pathway flow. A representative elementary volume study of the fluid saturation showed that this may be missed in smaller‐scale samples. Pressure drop measurements suggest that the observed pore‐scale fluctuations resulted in non‐Darcy like upscaled behavior. Overall, we show the usefulness of large field‐of‐view, high‐resolution imaging to bridge the gap between pore‐ and continuum‐scale multiphase flow studies.

An electrical analog permeability model assessing fluid flow in a decellularized organ

Background and objectiveIn recellularization, cell-seeding efficiency refers to the uniform distribution of cells across the decellularized organ, which should be enhanced to ensure effective functioning. During cell seeding, flow dynamics influence the distribution of cells because the driving force of cell movement is the fluid force. However, after decellularization, because of flow permeability through the vessel wall, the fluid pressure and velocity in the vessels of vascular trees are significantly reduced compared with those in the native organ, which might affect cell seeding efficiency. Therefore, it is necessary to assess the flow characteristics in the vessels of decellularized organs to select appropriate seeding conditions. Although electrical analog models have been widely used to investigate the flow distribution in organs, current models do not reflect the permeable conditions. This study proposes a model to extend the conventional electrical analog model to simulate the flow characteristics in decellularized organs. MethodsA resistor reflecting permeable flow was added to the original electrical analog model to describe the permeable conditions in the decellularized organs. Decellularization and pressure drop measurements of the kidney were also conducted for model development, calibration, and validation. The developed model was then applied to a decellularized kidney to reveal changes in flow characteristics. ResultsThe resistance calculation of permeable flow was determined for each generation of vascular trees. The coefficient of permeability can be indicated by the measured flow exiting through the outlet or the pressure drop across the decellularized organ. The developed permeability model had a qualitative and quantitative agreement with the experimental data without calibration. The results of the permeability model for the decellularized kidney indicated significant reductions of up to 70% in the flow rate and pressure of the organ compared to the native kidney. ConclusionsThe developed model can simulate the flow characteristics in each individual vessel of decellularized organs. The results from the model can be used to assess the optimal flow rate condition for the cell seeding process.

An improved method for feeding ash model compounds to a bubbling fluidized bed – CLC experiments with ilmenite, methane, and K2CO3

AbstractBiomass conversion with carbon capture and storage (Bio‐Energy CCS; BECCS) is one of the options considered for mitigating climate change. In this paper, the carbon capture technology chemical‐looping combustion (CLC) is examined in which the CO2 is produced in a stream separate from the combustion air. A central research topic for CLC is oxygen carriers; solid metal oxides that provide oxygen for the conversion process. Biomass and waste‐derived fuels contain reactive ash compounds, such as potassium, and interactions between the oxygen carrier and the ash species are critical for the lifetime and performance of the oxygen carrier. This work develops and demonstrates an improved method for studying the interactions between ash species and oxygen carriers. The method uses a lab‐scale reactor operating under fluidized conditions, simulating CLC batch‐wise by switching between feed gas. The novelty of the setup is the integrated system for feeding solid particles of ash model compounds, enabling the simulation of ash species accumulating in the bed. Ilmenite is a benchmark oxygen carrier for solid fuel conversion and was used in this study to evaluate the method using K2CO3 as a model ash compound. Experiments were done at 850 and 950°C. Methane conversion in CLC cycles and fluidization was evaluated with gas analysis and pressure drop measurements. Scanning electron microscopy and energy dispersive X‐ray spectroscopy (SEM‐EDS) and X‐ray diffraction (XRD) analysis of bed particles were done after the experiments to establish changes in the morphology and composition of the ilmenite. The method for feeding the ash model compound was concluded to be satisfactory. At 950°C, K accumulated in the particles forming K‐titanates and agglomeration was enhanced with K2CO3 addition. The agglomeration mechanism was solid‐state sintering between the Fe‐oxides forming on the particle surfaces. The bed defluidized at 950°C, but no such effect was seen at 850°C. The method is suitable for studying the Fe‐Ti‐K system with ilmenite and potassium without the influence of other ash species. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley &amp; Sons Ltd.

Fluidization of Swelling Particles at Elevated Temperatures

Semicrystalline polymer (e.g., polyethylene and polypropylene) particles may swell in solvent at elevated temperatures, inducing flow instability in operation, reactor blockage, and undesired product. Understanding the fluidization behavior of swelling particles at elevated temperatures is therefore of great significance. This work conducts an experimental study on the fluidization of polyethylene particles in an elevated-temperature liquid–solid fluidized bed. With the increase in temperature, particle swelling develops over two phases, i.e., non-cohesive swelling and cohesive swelling, which is different from the fluidization of cohesive particles in gas–solid systems. Four regimes can be identified through static bed height and pressure drop measurements, i.e., stable fluidization, noncohesive-swelling fluidization, cohesive-swelling fluidization, and full defluidization. A phase diagram was then obtained to demarcate these regimes. Furthermore, an energy balance model was proposed to predict the initial agglomerating temperature Tag of swelling particles for early warning of abnormal fluidization in practical operation.

Fates of Emitted Particles Depending on Mask Wearing Using an Approach Validated Across Spatial Scales.

The spread of emitted potentially virus-laden aerosol particles is known to be highly dependent on whether a mask is worn by an infected person and on the emission scenario, i.e., whether the person is coughing, speaking, or breathing. The aim of this work is to investigate in detail the fates of particles emitted by a person wearing a perfectly fitting, a naturally fitted mask with leakage, and no mask depending on the emission scenario. Therefore, a two-scale numerical workflow is proposed where parameters are carried through from a micro-scale where the fibers of the mask filter medium and the aerosol particles are resolved to a macro-scale and validated by comparison to experimental measurements of fractional filtration efficiency and pressure drop of the filter medium as well as pressure drop of the mask. It turns out that masks reduce the number of both emitted and inhaled particles significantly even with leakage. While without a mask, the person opposite of an infected person is generally at the highest risk of being infected, a mask worn by an infected person speaking or coughing will deflect the flow leading to the fact that the person behind the infected person might inhale the largest number of aerosol particles.

インホイール駆動システム向けダイレクト油冷技術の基礎評価

We are developing a small and lightweight direct-drive system toward realization in-wheel electric vehicles (EVs). To increase the power density of the motor, we developed a direct-cooling motor that immersed core, coils, and magnets in cooling oil and improved cooling efficiency. Moreover, we performed measurements of frictional loss, measurement of pressure drop, and continuous heat-run test on the test bench. The results demonstrated that direct cooling is effective and continuous operation can be achieved. Additionally, it was found that the coil temperature can be controlled by the flow rate of the cooling oil. In this paper, we report the concept of direct cooling and the measurement results.