Pressure Drop Phenomena Research Articles

Comprehensive Analysis of Pressure Drop Phenomena in Rotating Packed Bed Distillation: An In-Depth Investigation.

A rotating packed bed (RPB) is an innovative intensification technology that improves its separation capabilities in high-gravity conditions. This process increases efficiency with smaller equipment size and footprint than conventional packed columns. Although significant advancements have been made regarding RPBs, most studies only focused on single or dual rotor configurations in addressing dry pressure drop. Hence, multiple rotor systems in industrial settings can enhance economic efficiency by minimizing the necessity for numerous RPBs. This study investigated the pressure drops and holdup in a three-stage rotor-based RPB under actual process conditions using natural gas as the feed. A novel pressure drop correlation was introduced based on the nitrogen removal process from the natural gas in continuous RPB distillation operations. Consequently, the correlation between centrifugal acceleration, turbulent, and momentum effects demonstrated remarkable accuracy within ±15%. This outcome also highlighted the importance of meticulous design considerations in RPB-based applications due to the complex correlation between centrifugal forces, liquid holdup, and gas flow rates. The reflux feed ratio, liquid holdup, rotating speed, and F-factor effects were examined to comprehend the RPB distillation process. Overall, the correlations between the critical parameters offered crucial insights to prevent process upsets (such as flooding), contributing to advancing RPBs in practical industrial settings.

Computational and experimental analyses of pressure drop in curved tube structural sections of Coriolis mass flow metre for laminar flow region

ABSTRACT This research presents a comprehensive investigation into the computational and experimental aspects of pressure drop phenomena within the curved tube structures. Mass flow measurement holds critical significance in process industries to mitigate inaccuracies arising from fluid property variations. The CMFM stands as a reliable instrument for direct measurement; however, its performance has exhibited discrepancies, recording lower fluid flow magnitudes than actual values in laminar flow conditions. This anomaly is suspected to be attributable to a secondary force generated within the sensor's curved tube structure. This study seeks to elucidate this phenomenon by assessing the pressure drop resulting from the secondary flow in four distinct curved tube configurations: U, Omega, Delta, and Diamond shapes under steady-state conditions. The paper underscores the pressure drop characteristics inherent in each tube structure configuration, revealing that Basic U and Omega shaped tube structures exhibit the least pressure drop.

Exploring the Effects of Guide Vane on Dimpled Cooling Channel of Gas Turbine Blade

Abstract The purpose of the current study is to find out the heat transfer and pressure drop phenomena of the cooling channel with dimples and guide vane and compare the results with the no guide vane dimpled cooling channel. The first leg of the cooling channel is 490 mm, and the second leg is 460 mm. The two legs relate to the 180 deg turn region. The guide vane was inserted at the bend region of the dimpled cooling channel. The study was conducted with two different guide vanes geometry at two different orientations, i.e., U-guide vane with protrusion and depression orientation and curve-guide vane with protrusion and depression orientations both experimentally and numerically. The numerical study was performed with the large eddy simulation method. The result shows that for both stationary and rotational motion, the U-guide vane with depression experiences the highest thermal performance. The friction factor is comparatively higher for curve-guide vane with protrusion under stationary motion. However, under rotation, the curve-protrusion guide encounters the highest friction factor, which is higher compared to the no guide vane cooling channel.

Thermo-Fluid Physiognomies of a Photovoltaic Thermal Collector: A Comparative Study With Different Flow Channel Materials

Abstract In recent years, a good number of research works have been conducted to elucidate the different aspects of photovoltaic thermal (PV/T) technology. However, in order to take a technology to its maturity level, it is important to explore its internal physics and identify the factors that control system performance. With this view, in the present research, thermal and heat transfer characterization, and pressure drop phenomena inside a parallel-plate PV/T collector have been examined numerically to portray the thermo-fluid physiognomy of the system. A three-dimensional mathematical model of the PV/T system has been developed, and the model is used to build a computer simulation of the system in COMSOL Multiphysics® software. Hence, the simulation model has been validated by outdoor experimental results and was found to be in good agreement. Thus, the simulation program is employed to produce temperature distribution and heat flow plots throughout the flow channel, wherein results have been evaluated for two different channel materials, e.g., aluminum and copper. Results show that heat flowrate through both aluminum and copper channels is virtually the same. On the other hand, pressure drop, thereby pumping power required to maintain flow, is greater for an aluminum channel. The developed heat transfer simulation model can be extended for other PV modules with diverse designs and materials of the heat exchanger.

Well - test analysis for wells with gas rich CO2 in carbonate reservoir Song Hong Basin

The evaluations of properties of carbonate reservoirs containing gas with very high carbon dioxide (CO2) content often face many difficulties. In fact, there is a significal difference in interpretation results compared to conventional gas well testing due to: there is a gas to liquid phase transition; noise, abnormal increase or decrease in pressure and temperature during flow period, etc. These abnormal behaviors are all directly related to the specificity of CO2 properties with high compressible than that of natural gas, which can vary greatly density and can reach supercritical liquid state, transitioning solid to liquid or liqid to gaseous states even when pressure and temperature changes within a small range. During the testing of gas wells with high CO2 content, the phenomenon of pressure drop while pressure buid-up often occurs, leading to the analysis of reservoir parameters according to the conventional pressure build-up analysis method usually not feasible. The content of the article is aimed at researching and applying the method of interpreting well test data in the drawdown period while multi-rate flowing to more accurately estimate reservoir properties and mitigate risks in the design of the field development plan to achieve the economic efficiency.

Thermal design evaluation of ribbed/grooved tubes: An entropy and exergy approach

The smooth circular tubes are typically used in air-cooled heat exchangers systems. In literature, various research toward improving the hydraulic/thermal performance by changing the tubes' inner surface topology is found. In the current work, fluid friction and heat transfer characteristics of air-cooled tube heat exchangers with installed ribs and grooves have been numerically compared. Initially, the numerically calculated data of the ribbed tubes are validated /compared to the performance results in the literature. Performance evaluation criteria (PEC), entropy and exergy are numerically investigated for a tube with a group of ribs and grooves over the range of Reynolds number Re = 6700–20,000. Rib radius (r), number of ribs in the same group (Ng), the distance between two adjacent ribs (SL), and pitch between two adjacent groups (p) are the ribs parameters selected to study their effects on flow and heat transfer criteria. Also, the same evaluation criteria are performed on grooved tube with optimal parameters to make a comparison between results. Moreover, streamline patterns and temperature/pressure/velocity/turbulence kinetic energy contours are visually introduced to explicate the physics of heat transfer and pressure drop phenomena and to assess the flow structures inside different ribbed/grooved tubes. For the tubes with high-performance evaluation criteria (PEC), lower and higher entropy and exergy efficiency are determined. Recapitulation results from the technical comparison supported the use of grooved-tubes instead of ribbed-tubes. This is mainly due to lower flow irreversibility accompanied by higher PEC and exergy efficiency than those of ribbed tubes at the same flow condition.

Experimental analysis of HRSG for simulating internal flow behavior using Euler and swirl similitudes

Experimental analysis with a scale-reduction model enables data measurements and analysis of physical phenomena that could not be performed in a real model because of numerous constraining conditions and environmental regulations. In the present study, experimental analysis of a D-top model HRSG was conducted using a 1/12 scale-down model to simulate inlet duct flow behavior and pressure drop phenomena, and to evaluate numerical results. For a more accurate and reasonable study, the cold flow test was performed and pressure drop values of each section was adjusted considering geometric and dynamic similarities. Specifically, Euler and swirl numbers were considered as dynamic similitude procedures, and the log-Tchebycheff method was applied for effective data measuring. The flow uniformity at the rear section of the inlet duct and pressure drop values were measured, analyzed, compared with numerical results. Consequently, the experimental analysis rigorously evaluated the numerical results of the optimized model, which was proposed in the previous study.

Optimized Pressure Determined in Accordance with Variable Plunger Stroke of Internal Injector NGV

Using an analytical model, a clear investigation was performed into the phenomenon of decreasing overall pressure and velocity of a plunger when its stroke within a natural gas injector changes. The results indicated the following mesh sizes from the mesh matrix: 0.0005 mm minimum, 12.7 mm maximum, 1,107,420 nodes, and 5,856,567 elements. Consequently, the pressure was affected by the stroke height from the designed plunger shape, and although the height of the plunger stroke changes over 0.150 mm, the absence of the phenomenon of pressure drop was noticeable.

EVALUATION OF PRESSURE DROP IN FLOW OVER FIXED POROUS BED

Many studies are conducted about the dynamics of fluids in porous media, which generates a number of factors and problems are solved. In particular the phenomenon of pressure drop in flows on fixed bed, although fairly well in the form Ergun’s equation, still has certain inconsistencies with regard to the types of materials to be used in the packaging of the beds. The objective of this work is to study this phenomenon using some experiments reported in the literature to determine the pressure drop in fixed bed consisting of porous particles of açaí seed. Experimental studies were conducted to predict, and take into account the losses resulting from friction and inertia that showed strong dependence on velocity. The method of using the particular friction factor prediction as a way to replace the usual calculation and measurement of pressure drop. The analysis in the wind tunnel was made from different sizes of bed, with a decrease in arithmetic progressions corresponding to half the value of the diameter of the tube used in the test. Several bands of Reynolds number were also employed in order to be able to visualize how the phenomenon behaves on various tracks. For such a survey was necessary some parameters such as açaí seeds diameters, seed weight and volume occupied by the bed; these parameters are of vital importance in Ergun equation, because an important aspect of the phenomenon is the porosity which enters as a foundation in the theory of flow fixed bed. At the end of the study was found the divergence in big bands of the Reynolds number of the correlation between experimental data and the Ergun equation.

Experimental and numerical flow investigation of Stirling engine regenerator

This paper presents both preliminary experimental and numerical studies of pressure drop and heat transfer characteristics of Stirling engine regenerators. A test bench is designed and manufactured for testing different regenerators under oscillating flow conditions, while three-dimensional (3-D) numerical simulations are performed to numerically characterize the pressure drop phenomena through a wound woven wire matrix regenerator under different porosity and flow boundary conditions.The test bench operating condition range is initially determined based on the performance of the commercial, well-known Stirling engine called WhisperGen™. This oscillating flow test bench is essentially a symmetrical design, which allows two regenerator samples to be tested simultaneously under the same inflow conditions. The oscillating flow is generated by means of a linear motor which moves a piston in an oscillatory motion. Both the frequency and the stroke of the piston are modified to achieve different test conditions.In the numerical study, use of a FVM (finite volume method) based CFD (computational fluid dynamics) approach for different configurations of small volume matrices leads to a derivation of a two-coefficient based friction factor correlation equation, which could be later implemented in an equivalent porous media with a confidence for future regenerator flow and heat transfer analysis.

Numerical study of the pressure drop phenomena in wound woven wire matrix of a Stirling regenerator

Friction pressure drop correlation equations are derived from a numerical study by characterizing the pressure drop phenomena through porous medium of both types namely stacked and wound woven wire matrices of a Stirling engine regenerator over a specified range of Reynolds number, diameter and porosity. First, a finite volume method (FVM) based numerical approach is used and validated against well known experimentally obtained empirical correlations for a misaligned stacked woven wire matrix, the most widely used due to fabrication issues, for Reynolds number up to 400. The friction pressure drop correlation equation derived from the numerical results corresponds well with the experimentally obtained correlations with less than 5% deviation. Once the numerical approach is validated, the study is further extended to characterize the pressure drop phenomena in a wound woven wire matrix model of a Stirling engine regenerator for a diameter range from 0.080 to 0.110mm and a porosity range from 0.472 to 0.638 within the same Reynolds number range. Thus, the new correlation equations are derived from this numerical study for different flow configurations of the Stirling engine regenerator. The results indicate flow nature and complex geometry dependent friction pressure drop characteristics within the present Stirling engine regenerator system. It is believed that the developed correlations can be applied with confidence as a cost effective solution to characterize and hence to optimize stacked and woven Stirling engine efficiency in the above specified ranges.

Two-Phase Flow Across Small Sudden Expansions and Contractions

Two-phase flow approaching singularities such as abrupt expansions and sudden contractions is widely encountered in typical industrial and heat exchanging devices. There have been some studies concerning this subject but they mostly are applicable for larger channels. In this study, the first attempt is made to review the existing efforts concerning two-phase flow across sudden expansions/contractions and to examine the applicability of the existing correlations with respect to the recent data in small channels. The second part of this study presents some newly measured pressure drops and observed flow patterns pertaining to some special flow phenomena by expansion/contraction. For an abrupt expansion, it is found that the existing correlations all fail to provide a reasonably predictive capability against the newly collected data. Furthermore, a unique flow pattern called “liquid jet-like flow pattern” occurs at a very low quality region of total mass flux of 100 kg · m−2· s−1, and it raises a setback phenomenon of pressure drop. By contrast, an appreciable increase of pressure difference is seen when the liquid jet-like flow pattern is completely gone. A similar conclusion is drawn for the data of contractions. For the correlations/predictive models, the homogeneous model gives satisfactory prediction for conventional macro-channels but fails to do so when the channels become smaller. This is especially pronounced for a small-diameter tube with a Bond number being less than 1, in which the effect of surface tension dominates.

Transcritical CO2 Heat Pump Dryer: Part 1. Mathematical Model and Simulation

In this study, a mathematical model and simulation code has been developed to investigate the performance of a transcritical CO2 heat pump dryer. The model takes into account detailed heat and mass transfer and pressure drop phenomena occurring in each component of the system. To take care of the variable heat transfer properties, the heat exchanger components were divided into several infinitesimal segments to examine the state, heat and mass balance and pressure drop for both refrigerant and air, and hence accurate results are expected. In Part 2 of the article, the model developed has been validated with experimental data and then the model was used to investigate effects of important operating parameters on the performance.

Forced convective heat transfer across a pin fin micro heat sink

This paper investigates heat transfer and pressure drop phenomena over a bank of micro pin fins. A simplified expression for the total thermal resistance has been derived, discussed and experimentally validated. Geometrical and thermo-hydraulic parameters affecting the total thermal resistance have been discussed. It has been found that very low thermal resistances are achievable using a pin fin heat sink. The thermal resistance values are comparable with the data obtained in microchannel convective flows. In many cases, the increase in the flow temperature results in a convection thermal resistance, which is considerably smaller than the total thermal resistance.

Single-Phase Heat Transfer and Pressure Drop Performance in Smooth Tubes with R-22, R-134a, R-407C, and R-410A at Superheated Conditions with Lubricant Mixtures (RP-1067)

This report presents results from an ASHRAE-sponsored research project designated RP-1067. The objective of this study was to document the heat transfer and pressure drop phenomena of selected refrigerants in a superheated state with lubricant mixtures. Refrigerants used in this study included R-22, R-134a, R-407C, and R-410A. This paper presents the smooth tube results over a Reynolds number range of 100,000 to 1,000,000, with lubricant concentrations ranging from 0% to 5% by mass. The refrigerant saturation temperature was maintained at 40°C, which would be common for the inlet of a condenser. The results show that even small additions of lubricant cause significant increases in pressure drop. The lubricant also causes a less dramatic increase in the heat transfer coefficients. Models are proposed to allow prediction of superheated refrigerant and lubricant mixture performance.

Two-phase flow redistribution phenomena in a large T-junction

An experimental study into phase redistribution and pressure drop phenomena of two-phase (air-water) flow splitting in a horizontal upward reduced T-junction was carried out in an industrial-scale flow rig (inlet and run dia = 23 cm , branch dia = 10 cm ). Measurements were performed with inlet conditions in the stratified smooth, stratified wavy and bubbly flow regimes. The inlet liquid mass flow was varied between 75 and 225 m 3/h, the inlet quality was < 0.03%. The experiments reveal that the flow split phenomena observed in this large-scale T-junction, generally, do resemble those reported in the literature for smaller scales. Within that region, several models developed for smaller scales can be used to qualitatively describe the flow split and pressure drop at larger scales as well. It was observed that flow phenomena and regimes downstream of the junction still have impact on the flow split. In particular, the occurrence of pulsations in the branch causes a striking change in the phase redistribution behaviour within the junction. The transition from churn flow to pulsating churn could be determined quite distinctively by monitoring the time signals of the various pressure transducers along the flow path and their fast Fourier transforms.

The effect of fine material on the structure and resultant pressure drop of a bed charged against an uprising gas stream

Experiments were performed in which mixtures of up to 20 volume per cent of small sized material in large sized material—from 3 to 6 times the size of the small material—were charged against an uprising gas stream to form a bed. Measurements of the pressure drop and bed bulk density were taken at completion of charging and with the air stream volume flow rate maintained at the charging value. Plots of the recorded pressure drops versus the charging air velocity gave maxima, which, for different percentages of fine material, showed little variation in magnitude but which occurred at different air velocities. The maxima were much smaller than the pressure drop required for fluidization. The limitation of the pressure drop was due to the mobility of the fine material in the bed during the charging procedure, with consequent alterations to the bed structure, which were reflected quantitatively by changes in the bed voidage and by the friction factor deviations—defined by equation (3). Changes in the bed voidage could account for most of observed pressure drop phenomena. The beds formed in the presence of an air flow were stable, in so far as a reproducible pressure drop curve could be obtained by reducing the air flow to zero and then increasing it once more to the charging value. The results are of particular application to blast furnaces, whose operation the experiments were meant to simulate.