Change In Pressure Drop Research Articles

Numerical Simulation of Hydrodynamic Properties of Perforated Corrugated Sheet Materials

Packings are widely used as important materials in the chemical industry, but their internal structure is complex and the study of their internal fluid dynamics is still challenging. The hydrodynamic properties inside a Perforated corrugated sheet packing are simulated. The flow field characteristics of the packings with different pore sizes and the main mechanisms causing changes in the dry pressure drop were analyzed. It was found that the drag coefficient gradually converges to a constant as the Reynolds number increases. The factors affecting the variation of dry pressure drop varied with the Reynolds number. Under low Reynolds number conditions, the drag coefficient is the main influencing factor, while with the increase in Reynolds number, the role of the drag coefficient gradually decreases and the void fraction becomes the main influencing factor. The conclusions obtained can be used as a reference for the optimal design of packing.

Convective heat transfer in porous channel with multi-layer fractures under Local thermal non-equilibrium condition

Based on Brinkman-extended-Darcy model and Local thermal non-equilibrium (LTNE) model, analytical solutions of velocity and temperature fields, pressure drop and Nusselt number of porous channels containing different number of fracture layers are obtained. The characteristics of fluid flow and heat transfer in multi-layer parallel fractured channels are further studied. Results show that for a single-layer or multi-layer fractured channel, the pressure drop changes sensitively at small hollow ratio and increases as the number of fracture layers increases with decreasing increase degree, but the pressure drop tends to be consistent regardless of the number of fracture layers when Darcy number is high. For small ratio of effective thermal conductivity, LTE model is valid regardless of Biot number, and the heat transfer intensity in multi-layer fractured channels is always higher than that in single-layer fractured channel at any hollow ratio, but the heat transfer intensity is still low. For large ratio of effective thermal conductivity, increasing Biot number or fracture layer number makes the Nusselt number increase under very small hollow ratio for both single and multiple fracture cases, and when both the ratio of effective thermal conductivity and Biot number are high, there is an intersection point occurs at hollow ratio near 0.1, which makes same heat transfer effect under different fracture numbers.

Visual study of hydrate particles agglomeration and rolling characteristic in gas-oil-water phase using a flow loop

Natural gas hydrate blockage always leads to safety problems in oil and gas transportation pipelines. It is important to look for the characteristic of hydrate blockage process. The hydrate blockage was visually investigated under gas-oil-water multi-phase flow conditions in a flow loop in this study. The change of pressure drop with water conversion rate variations were detected. The hydrate particle movements were also observed in the visual pipes at different liquid loadings and water cuts. It was found that the hydrate particles may agglomerate and deposit with an obvious rolling process in low water cut conditions. The oil phase will accelerate particles agglomeration in the contact interface of oil, gas and water, and form a large number of flocculent hydrates. A theoretical hydrate particle rolling model was conducted to analysis the experiment results, and the hydrate particle velocity increases first and then decreases with the increase of particle diameter due to the comprehensive influence of van der Waals force and drag force. The results also confirmed the maximum of the pressure drop increased when the liquid loading increased. However, the hydrate formation and blockage speed also slow down due to small component of the gas phase in high liquid loading. In addition, comparing with 20 % and 80 % water cut, 50 % water cut has the fastest hydrate formation speed in different experimental conditions. Furthermore, the maximum water conversion rate increased with have a higher water cut. More hydrate will form in the condition, which will lead to the decrease of flow velocity in the pipeline.

Analysis of thermo-hydraulic flow and optimisation heat augmentation in 3D dimpled pipe based on design of experiment method and Taguchi technique evaluation

In this work, the numerical analysis concentrates on investigating thermal flow patterns, pressure drops, varying velocity components and heat transfer behaviour. Impacts of four parameters on the enhancement of thermohydraulic performance are carried out using three-dimensional calculations employing CFD techniques: different spacing, diameter, number and distance for dimples were investigated. Additionally, utilising a design of experiments (DoE) strategy together with the Taguchi technique (TT) and response surface methodology (RSM), the impacts of the factors listed below are optimised. The results indicated that the different flow fields and heat transfer patterns were because of the use of depressions on the tube's inner surface. A comprehensive flow investigation with the dimple and tube wall was established to explain the mechanism of pressure drop and heat transfer change. The results of orthogonal experiments show that the optimal design of the spiral tube in this investigation using computational fluid dynamics using DoE, RSM and TT has a temperature difference and heat transfer coefficient of about 35.75% and 36.1% higher improved pipes. The results show a high PEF value greater than 1. According to the above results, various design applications require flow hydrodynamic analysis and heat performance enhancement.

Effects of temperature on gas-solid bubbling fluidization with Geldart A particles characterized by electrical capacitance tomography and pressure drop measurements

The fluidization with Geldart A particles could be usually operated at high temperature which can significantly influence the fluidization behaviors. This paper describes the impacts of temperature on the fluidization of Geldart A particles using electrical capacitance tomography (ECT) and pressure drop measurements. Alumina particles, classified as Geldart A particles, are studied in a fluidized bed across a temperature range of 20 °C to 600 °C. As the superficial gas velocity increases, the minimum fluidization velocity and the minimum bubbling velocity are observed based on the change of solid fraction and pressure drop at high temperatures. As temperature increases, both the minimum fluidization velocity and minimum bubbling velocity decrease, and the solid fraction decreases. The trend agrees well with empirical correlations which consider the change of gas density and viscosity with temperature. Specifically, the increase in temperature leads to a higher gas viscosity, which enhances the hydrodynamic forces and significantly influences the fluidization behaviors. The broad agreement between ECT and pressure drop measurements suggests that ECT can be applied for the characterization of fluidization behaviors at high temperatures.

Research on Gas-Assisted Extrusion of Elastic Material Round-Tube for Flexible Robot Body.

The flexible robot is widely used in a variety of fields such as medical treatment, rescue and disaster relief, industry, and agriculture. Using elastic materials to prepare flexible robot body structures is the core of the study of flexible robots. Due to the small selection of materials, single preparation method, and long fabrication time, in this study, a new method of gas-assisted extrusion (GAE) of elastic material round-tube for flexible robot body was proposed, and the numerical simulation of GAE was carried out with nonsilicone elastic material round-tube under different viscosities. The results showed that with the change of viscosity, the velocity, pressure drop, and shear rate of melt in all directions change accordingly. When the viscosity is too small or too large, it is easy to bring negative effects on the GAE process of elastic materials. TPE and TPU were completely plasticized in the GAE, and the surface of the extruded elastic products was smooth and straight, with full gloss. Therefore, in the preparation of the flexible robot body, nonsilicone elastic materials and GAE forming methods can be considered.

Experimental Heat Transfer Analysis of a New Turbulator in a Concentric Heat Exchanger Tube: A Full Factorial Design Approach

Abstract People have been looking for alternative energy sources because current sources may be depleted. Furthermore, it is critical to utilize available energy sources as effectively as possible. Turbulators are among the topics to consider when it comes to energy efficiency. In practice, turbulators are often used in exchangers to enhance heat transfer. Putting newly constructed turbulators in determined locations of the constant surface temperature heat exchanger, velocity, temperatures, pressure, and flow measurements have been performed in the inlet and outlet. In the case of using different numbers of turbulators, their placement in different locations, their arrangement at different distances, and their use at different Reynolds, the changes in pressure drop, Nusselt number, friction factor, efficiency, exergy loss rate, and NTU were determined with the full-factor experimental design. When the test data were evaluated, it was seen that as the number of turbulators increased, the thermal efficiency, friction factor, and pressure loss also increased. Using turbulators in different numbers, at different positions, at different distances, and with different Reynolds numbers, the effect ratio on the pressure loss, Nusselt number, and friction factor parameters was detected. In the analyses made, the most efficient parameters on heat transfer were determined, respectively, as Reynolds number (64.55%), the position of turbulators (19.73%), the distance between turbulators (6.09%), and the number of turbulators (5.94%).

The Effect of Ablution on Changes Blood Pressure in The Elderly with A History of Hypertension at Ibnu Sina Hospital

Objective: To find out the effect of ablution on changes in blood pressure in the elderly with a history of hypertension at Ibnu Sina Hospital. Methods: Seeing changes in blood pressure drop momentarily in hypertensive patients before and after ablution, with data collection carried out at one time. Then, it is carried out through the "one group pretest and post-test design" in elderly with history of hypertension at Ibnu Sina Hospital. Results: There was a significant decrease with p value= 0.001 in systole and p value= 0.029 in diastole. The decrease occurs starting at the 5th minute of both systole and diastole, especially at the 15th minute. Mean value of difference in blood pressure before and after ablution at 5 minutes (systole 6.20 mmHg, diastole 4.70 mmHg), at 10 minutes (systole 11.57 mmHg, diastole 9.40 mmHg), at 15 minutes (systole 15.03 mmHg, diastole 11.53 mmHg). Conclusion: There was a decrease in blood pressure shortly after ablution in elderly people with hypertension.International Journal of Human and Health Sciences Supplementary Issue 01: 2024 Page: S64

Numerical Calculation of Gas–Liquid Two-Phase Flow in Tesla Valve

In this paper, the gas–liquid two-phase flow within a Tesla valve under zero-gravity conditions is numerically studied. Based on the VOF model and the inlet two-phase separation method, the forward and reverse flow patterns and pressure drop changes in a Tesla valve at different inlet velocities were analyzed. At an inlet velocity of 0.1–0.2 m/s, the flow pattern was slug flow, the bubbles were evenly distributed in different positions in the Tesla valve, and the velocity difference between the main pipe and the arc branch pipe was small. When the inlet velocity was 0.4 m/s, the main flow pattern was annular flow, and there was a phenomenon of gas–liquid phase separation through different flow channels, which was related to centrifugal force. At an inlet velocity of 0.6–0.8 m/s, bubbly flow and slug flow coexisted, which was related to the uneven velocity. In the study range, the difference in the forward and reverse pressure drops of two-phase flow was smaller than that of single-phase flow, and the two-phase diodicity decreased first and then increased with the change in inlet velocity, reaching minimum values of 0.78 at 0.2 m/s and 1.44 at 0.8 m/s.

An investigation of the filtration performance and mechanism of oil-solid mixed particles on filter materials with different wettability

In the process of air filtration, filter materials may encounter oil-solid mixed particles from various sources such as industry and household, and the influence of filter material with different wettability on the filtration performance of oil-solid mixed particles has not been fully reported. The objective of this study was to prepare filter materials with varying wettability properties and investigate their filtration performance for oil-solid mixed particles with diverse oil contents. In this study, four filter materials were prepared using the impregnation method, exhibiting 0° (superoleophilic), 46° (oleophilic), 90° and 122° (oleophobic) oil contact angles. The oil-solid mixed particles with varying oil contents were loaded on the four different filter materials. The loading behavior of the filter materials was characterized from two aspects: macroscopic loading behavior (changes in pressure drop and DHC) and microscopic particle deposition behavior. The results demonstrated that, under the conditions of 25% and 50% oil content, the enhanced liquid bridge force between the oil-solid mixed particles on the oleophobic filter material facilitated the formation of a loose and porous cake layer structure compared with other filter materials, resulting in a lower growth rate of pressure drop and a higher dust holding capacity (DHC). However, in 75% and 100% oil content environments, the superoleophilic filter material owned a remarkably high affinity for oil particles compared with other filter materials, leading to the gradual formation of an oil film structure on the filter material, yielding lower the growth rate of pressure drop and higher DHC. These findings shed light on the mechanism of particle deposition under diverse filtration conditions and are applicable to the filtration of various oil-solid mixed particles over a wide range of oil contents.

Microfluidic flow synthesis of Al2O3 nanofluids for efficient phase-change boiling heat transfer enhancement of electronic devices

Integrating microchannel flow boiling heat transfer with nanofluids is an effective method for cooling electronic devices. However, traditional methods have significant limitations in achieving facile synthesis of nanofluids with desirable properties. In this study, we propose a straightforward synthesis strategy using microfluidic reactors, which enables continuous and high-throughout synthesis of Al2O3 nanofluids with high purity and long-term stability. These nanofluids were found to enhance boiling heat transfer performance by delaying bubbles coalescence, increasing surface nucleation sites, improving the nucleation rate, and enhancing wettability by observation of the bubble behavior. Specifically, the critical heat flux (CHF) and corresponding heat transfer coefficient (HTC) are increased by a maximum of 32 % and 26 %, respectively, with negligible change in pressure drop. Moreover, the heat transfer performance deteriorates with increasing concentration of alumina nanofluids. These findings not only provide guidance of microchannel flow boiling with nanofluids, but also present valuable insights for the application of nanofluids in two-phase cooling systems for electronic devices.

Flow field analysis of cigarette filter through micro-CT-based geometries and CFD simulation

The cigarette filter is an essential component of modern cigarettes and studying the flow distribution within the cigarette filter is of great significance in reducing the harm of cigarettes and optimizing smoking sensations. As the object of numerical simulation research, a three-dimensional model of the cigarette was accurately constructed through micro-CT reverse engineering, achieving a scanning accuracy of 4.05 μm. An overall porous media model of the cigarette filter was established to characterize the pressure distribution inside the filter. Based on the three-dimensional reconstruction, a local simulation model of the cavity-filtered filter was created by extracting a 1/36 geometric model. The simulation results of the overall porous media model of the cigarette filter were used as the pressure boundary conditions for the local simulation model of the cavity-filtered filter, and the effects of the wrapped paper and cavity on the flow field were analyzed. The results show that the simulated pressure drop in the overall porous media model of the cigarette filter had a deviation of less than 3.5% compared to the experimental results. This suggests that the porous media model can effectively predict the changes in pressure drop within the filter. When both wrapped paper and cavity were present, the velocity at the interface between acetate fiber and wrapped paper increased by 141.54%, while the pressure approached 0 Pa. Similarly, at the interface between acetate fiber and cavity, the velocity increased by 130.77%. It indicates that both wrapped paper and cavity significantly influenced the flow field characteristics within the cigarette filter. Additionally, as the porosity of the wrapped paper gradually increased from 0.69 to 0.99 in the radial direction, the fluid velocity increased by 14.46%, while the fluid pressure decreased by 29.09%. These changes were particularly evident when the porosity was below 0.87.

Crossflow polymeric hollow fiber heat exchanger: fiber tension effects on heat transfer and airside pressure drop

In various applications, a polymeric hollow fiber heat exchanger (PHFHE) is a competitive alternative to a conventional heat exchanger (HE). Standard empirical models for predicting the crossflow tube HE characteristics are defined for devices with rigid tubes with relatively large diameters compared to the polymeric hollow fibers with an outer diameter of around 1 mm. This study examines the impact of tension force on airside heat transfer rate and pressure drop in a crossflow PHFHE. The tension force influences the stiffness of the flexible polymeric fibers and their response to applied airflow. Two liquid–gas PHFHEs were designed and manufactured to ensure uniformity of the fibers' arrangement (inline and staggered). An experimental stand enabling the application of defined tension force in the range of 0–9000 N was designed, manufactured and placed into the calorimetric tunnel, where heat transfer rate and pressure drop measurement were performed with varying air velocity between 2 and 8 ms−1 (corresponding to Reynolds number of 240–970). Among our key findings was that the elongation of the fibers due to thermal expansion or stress relaxation has a considerable impact on the fibers' arrangement and resulting fluid flow. Moreover, the application of tension force yielded no substantial change in air pressure drop; however, it led to a notable enhancement in heat transfer rate. Specifically, under a maximal tension force of 9000 N, the heat transfer rate increased by around 11% compared to the unloaded state.

Numerical investigation of louver edges effect on the performances of louvered fin compact heat exchanger

The rectangular channel louvered-fin compact heat exchanger (LFCHE) is the most efficient type that has been served in a radiator. However, with this type of heat exchanger, the pressure drop rises by three to four times as the heat transfer increases, which results in decreasing performance. This research is aimed to numerically investigate the louver edges (vertical, inclined, and horizontal) effect on LFCHE performance at different louver angle (θ) with air inlet velocities ranging from 1 to 30 m/s. A total of twelve models are made and simulated. The result revealed that the horizontal edge decreases the pressure drop up to 24.2% with a 1.01% increase in outlet air temperature over the base model (inclined edge). Thus, louver edge has design which results in higher and lower effect on pressure drop and temperature change, respectively. The research investigated the effects of louver edges using different performance evaluation criteria. At 10 m/s (Relp = 972.33) the horizontal edge increases the volume goodness (jf) factor up to 21.49% over the base model. Similarly, the horizontal edged fins resulted in maximum increment of jf-factor by 22% and 25% as compared with inclined edge for louver angles θ of 24 ° (at low Relp) and 20 ° (at high Relp), respectively. Generally, the horizontally edged LFCHE is proven to have higher performance in cooling the coolant with a minimum air side pressure drop.

A Study on the Pressure Drop Changes by Design of Noise Mitigation Device in HVAC Equipment

A Study on the Pressure Drop Changes by Design of Noise Mitigation Device in HVAC Equipment

The Influence of Temperament on the Conveying Efficiency of UCG High Temperature Gathering Network

Due to the particularity of its gas source area and transportation medium, the factors affecting the efficiency of UCG pipeline transportation are also more complex than those of conventional natural gas. The dendriform UCG pipeline network model is designed through pipe network simulation software, aiming at different component conditions such as moisture, coal tar and dust, and aiming at different pressure and pressure drop changes of wellsite, branch line and trunk line respectively for quantitative analysis. The results show that the increase of the proportion of CH4 and H2 can improve the transport efficiency. With the increase of the proportion of H2O components, the transport efficiency will decrease. Tar in the group does not increase the transportation efficiency, and if the component is large, it will lead to liquid phase in the pipeline and reduce the transportation efficiency; The appearance of dust will reduce the efficiency of transportation.

Numerical study on flow characteristics in the primary side of a once-through steam generator under ocean conditions

The flow characteristics of the primary side of the helical coil once-through steam generator (OTSG) have a significant impact on the safe operation of the reactor. Different from the land-based stationary working conditions, the flow of the primary side of the OTSG is influenced by sea waves and winds under ocean conditions. The rigid body motion model is used to calculate the flow of the primary side under different ocean conditions, including heeling, trimming, rolling, pitching, heaving, and combined conditions. The results show that under heeling and trimming conditions, the static pressure of the primary side is different from that under vertical conditions due to the influence of gravity, but its impact on the flow field is relatively small. Under rolling and pitching conditions, the mean flow velocity and pressure drop change periodically with the movement of the OTSG, and the smaller the sway angle, the smaller the variation amplitude of the mean flow velocity and pressure drop. Under the heaving condition, the variation amplitude of the mean flow velocity is greater than that under rolling and pitching conditions, and reverse flow occurs. Under the combined heaving and rolling condition, the mean flow velocity and pressure drop are influenced by the period and amplitude of both the two motions.

Pore-scale Simulation of Two-phase Flow in Foamed Porous Materials

This paper establishes a pore cell model of foamed silicon carbide material based on a tetradecahedron structure, and uses FLUENT software to numerically study the flow rate and pressure drop changes in the porous structure at different flow rates and the gas-liquid two-phase flow state of the channel. The research results show that the porous skeleton structure has a great influence on the velocity and pressure distribution in the calculation domain; the inlet flow velocity has a certain impact on the gas-liquid mixing zone and gas-liquid interface area in two-phase flow. The application of tetradecahedral porous media increases the thickness of the gas-liquid mixing zone and the phase interface area are increased, with a maximum increase of 11.5%, thus promoting gas-liquid heat and mass transfer.

Development and Testing of a System Thermal-Hydraulics Model for a 50-MWel-Class Pressurized Water Reactor–Small Modular Reactor

Abstract This paper describes the development, analysis, testing of a RELAP5-3D system thermal-hydraulics model for a 50-MWel-class pressurized water reactor–small modular reactor (PWR–SMR), similar to that by NuScale Power. This study focuses on a series of sensitivity tests to investigate the impacts of model changes. Parameters considered in the sensitivity study included the surge line junction resistance (SLJR), steam generator (SG) heat transfer area (SGHTA), SG primary flow area (SGPFA), SG secondary pressure (SGSP), and SG secondary flowrate (SGSF). Results for the reference and sensitivity simulations are compared with available design data. The flow in the primary circuit of the PWR–SMR is driven by natural circulation and can be sensitive to changes in hydraulic resistance and pressure drop in system components. Initial analysis results demonstrated significant flow oscillations. As a result of sensitivity studies, it was found that the surge line junction resistance needed to be increased by increasing the form loss coefficient from 4.9 to 30.0, to reduce mass flow oscillation amplitude to less than ±2%. Modifications to the steam generator heat transfer area, primary flow area, or secondary pressure have very little impact in reducing flow oscillations. However, it was found that the steam generator secondary flowrate will affect primary circuit flow oscillations, and when the SGSF was artificially increased from 68 kg/s (design data) to 91 kg/s (a 36% increase), the oscillations were eliminated, along with better matching with design data for core flowrate and inlet/outlet temperatures. Further improvements to the model for the steam generator will be required.

Ultrasonic aerosol agglomeration: Manipulation of particle deposition and its impact on air filter pressure drop

Acoustic agglomeration is a technique that leverages on sound waves to promote the collision of aerosol particulate matter, thus leading to the formation of larger particle agglomerates. In this study, this acoustics-driven phenomenon is demonstrated for its usefulness as an aerosol pre-conditioning method to significantly enhance the efficiency of filtration systems in particle treatment processes. Specifically, favorable changes in pressure drop across the filters are observed as a result of receiving less particle mass, for which filters are shown to be able to have their operational life extended remarkably by more than 50%. The involved ultrasonic aerosol agglomeration mechanisms are unveiled through numerical simulations, and the effects of residence time, sound pressure level, and initial particle number concentration on agglomeration performances are experimentally investigated. In addition, validations and measurements of filter pressure drop are obtained through a series of experiments. This study provides a comprehensive overview to the design and performance characterization of acoustics-agglomeration-enhanced filtration systems, which could potentially derive energy savings for fan power in ventilation systems and be scaled up for applications in industrial plants for reducing carbon emissions.