bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of Subcooled Water Flow Boiling CHFS for Outlet Subcooling at a Flow Velocity With Pressures for Test Sections With Various Shapes
Authors: Sakurai Akira , Fukuda Katsuya 
Published: November 2021

Abstract
The mechanisms and the correlations for the subcooled water flow boiling CHF, qct,sub, for outlet subcooling at fixed flow velocities with the pressure as a parameter measured were investigated using the existing database measured for the test sections such as a vertical metal strip in the channel with a wide cross section, and the vertical tubes having the inside diameters ranging from 0.4 to 12 mm and the length-to-diameter ratio ranging from 2.4 and 96.6 with water flowing upward based on the unified subcooled pool and flow boiling CHF correlations previously presented: the unified CHF correlations based on the two different mechanisms due to the hydrodynamic instability (HI) and the heterogeneous spontaneous nucleation (HSN). The qct,sub versus outlet subcooling, ΔTsub,out, for the test tubes at a flow velocity with the pressure were clearly divided into four regions for the ΔTsub,out in general: namely, first, the qct,sub decrease down to minimum one for low ΔTsub,out (1st Region), secondly, the qct,sub increase up to maximum one for middle ΔTsub,out (2nd Region), thirdly, the qct,sub considerably decrease down to minimum one for transition ΔTsub,out (3rd Region), and finally, the qct,sub again increase monotonously for high ΔTsub,out (4th Region) with an increase in ΔTsub,out. The trend of the qct,sub versus the ΔTsub,out, in the third region for the transition ΔTsub,out became significant with a decrease in tube inside diameter though the trend of the qct,sub for the tubes having large inside diameters of 9 and 12 mm became insignificant. It was clarified that the qct,sub data for middle ΔTsub,out (2nd Region) and those for high ΔTsub,out (4th Region) for the test sections with various shapes of the metal strip and the tubes having the inside diameters ranging from 0.4 to 12 mm and length-to-diameter ratio ranging from 2.4 to 96.6 were well expressed by the unified subcooled water flow boiling CHF correlations derived based on the existing database.
Development of Pressurizer Transient Thermodynamics Analysis Code for Chashma Nuclear Power Plant
Authors: Mahmood Arshad , Jun Xu Ji 
Published: November 2021

Abstract
A computer program PRETTA “Pressurizer Transient Thermodynamics Analysis” has been developed for the prediction of pressurizer under transient conditions. It is based on the solution of the conservation laws of heat and mass applied to the three separate and non equilibrium thermodynamic regions. In the program all of the important thermal-hydraulics phenomena occurring in the pressurizer: stratification of the hot water and incoming cold water, bulk flashing and condensation, wall condensation, and interfacial heat and mass transfer have been considered. The bubble rising and rain-out models are developed to describe bulk flashing and condensation, respectively. To obtain the wall condensation rate, a one-dimensional heat conduction equation is solved by the pivoting method. The presented computer program will predict the pressure-time behavior of a PWR pressurizer during a variety of transients.
The results obtained from the proposed mathematical model are in good agreement with available data on the CHASHMA nuclear power plant’s pressurizer performance using RETRAN.
Simulating Analysis for Small Break LOCA Test Facilities by Applying the Volume Scaling With Reduced Pressure and Reduced Height
Authors: Moussavian S. K. , Salehi M. A. 
Published: November 2021

Abstract
In this paper first we briefly define the different scaling schemes and scaling logic in which we use these schemes to simulate the Small-Break Loss Of Coolant Accident (SB-LOCA) in test facilities. The simple loop of the test facility is considered and the mass, momentum and energy conservation equations are used for the derivation of the scaling model. The variations of mass flow rate, pressure drop and the void fraction in the loop as functions of the time scale or the inventories are obtained. Finally, the calculated results from the simulating schemes are compared with the experimental data previously obtained in an integral test facility.
A Study of Transient Heat Transfer in a Vertical Two-Phase Flow During Blowdown of a Pipeline
Authors: Bautista-Fragoso S. , Fairuzov Yuri V. 
Published: November 2021

Abstract
A numerical model of transient two-phase flow and conjugate heat transfer in a vertical pipeline is presented in the present paper. The drift-flux model is used to describe the fluid flow in the pipeline. The modeling of transient conjugate heat transfer is based on a mathematical formulation in which the pipe wall and the fluid are assumed to be in local thermal equilibrium. The effect of the thermal capacity of the pipe wall is taken into account by an additional term in the energy equation for the fluid flow. Such an approach allows significant simplifying the problem and reducing the computer running time. Numerical simulations of blowdown of a pipeline/riser system were performed. The effect of the pipe wall on the flow behavior was investigated.
Study on Enhancement of Critical Heat Flux by Supplying Liquid-Jets to Heating Surface: Mechanism on Enhancement of CHF and Measurement of Void Fraction Near Heating Surface
Authors: Ohtake Hiroyasu , Liu Kun , Koizumi Yasuo 
Published: November 2021

Abstract
The enhancement of a critical heat flux — CHF — in pool boiling was investigated by supplying liquid-jets to a heating surface, as a proposal of the high heat removal technology for the future industrial field. The mechanism on the enhancement of CHF was examined through measurement of void fraction near the heater by using a void probe and macrolayer model of CHF by Haramura-Katto.
Experiments were conducted using a copper block and saturated water for a pool condition at 0.1 MPa. One, two or three jet-nozzles were set away a certain distance from the test surface, 1 or 6 mm, for supplying liquid-jets to the heating surface. The effects of the distance, the diameter of jet-nozzles, 0.9, 0.5 or 1.5 mm, the liquid flow rate and the jet-velocity on the enhancement rate of the CHF were examined experimentally.
The CHF was enhanced by supplying three liquid-jets a factor of about three for 6 × 10−6 m3/s in the flow rate. The enhancement rate increased with the liquid flow rate and jet-velocity. The void fraction near the heating surface was a lower value by the supplying liquid-jets when the heat flux was similar to the normal CHF without the supplying liquid. These results suggests that the enhancement of the CHF is affected additionally by the quantity of supplied liquid to the macrolayer on the heating surface.
RBHT Steam Cooling and Droplet Injection Pre-Test Analysis Using COBRA-TF
Authors: Frepoli C. , Ireland A. J. , Hochreiter L. E. , Cheung F. B. 
Published: November 2021

Abstract
The droplet injection experiments to be performed in a 7 × 7 rod bundle heat transfer test facility are being simulated using an advanced thermal hydraulics computer code called COBRA-TF. A current version of the code, which provides a three-dimensional, two-fluid, three-field representation of the two-phase flow, is modified to facilitate the simulation of the droplet field produced by the injection system in the test facility. The liquid phase is split into a continuous liquid field and droplet field where a separate momentum and mass equation is solved for each field, with the effects of spacer grids being properly accounted for. Pre-test analyses using the modified COBRA-TF code have been conducted for different injection conditions. Results indicate that there are specific ranges of conditions that can be simulated within the facility constraints to provide for validation of the dispersed flow film boiling models. The numerical results also show important effects of the spacer grids on the local heat transfer in the dispersed flow film boiling regime.
Prediction of Heat Transfer Rate and Pressure Drop of a Humid Flue-Gas Flow Across a Tube Bank for Waste Heat Recovery
Authors: Jeong Dong Woon , Lee Sang Yong , Park Byung Kyu 
Published: November 2021

Abstract
A simulation program taking into account of the mass transfer effect was constructed to estimate the heat transfer rate and the pressure drop of a flow of humid flue gas across a tube bank. Higher heat transfer rate is expected when the flue gas temperature drops below the dew point because of the vapor condensation effect at the external surface of the tubes. The temperature variations of the flue gas and the cooling water and the pressure drop across the tube bank were compared with the experimental data reported previously. The predicted results for the temperature variations without any correction factor agree satisfactorily with the experimental data. As for the shell-side pressure drop, the single-phase friction factor for the tube-bank flow adopted. With this simulation program, the parametric studies have been conducted for various operating conditions, such as the velocities and temperatures of the vapor/gas mixture and the cooling water, the number of the tube-rows, and the conductivity of the wall material.
The Flow Regime of Oil-Gas-Water Three-Phase Flow in Pipes
Authors: Wang Yueshe , Zhou Fangde 
Published: November 2021

Abstract
The experiment for oil-gas-water flow pattern transition is carried out in a vertical tube 40mm I.D. and 6m long with a wide range of mixture velocity. Applying the concept of Weisman’s flow pattern transition zone to the investigation on oil-gas-water flow regime, every transition is quantified. The flow regime map, which includes transition zone mentioned above, is compatible with a lot of other pattern transitions. Meanwhile, according to this map the divergence of numerous transitions can be explained. So, that provides a reliable for reasonable understanding of the pattern transitions. Consequently, a method for regime recognition has been put forward with using simultaneously optical fiber probes and conductance probes. The availability of the method can be proved by the images of High Speed Motion Analyzer, which is from Kodak Company.
Flow Configure in Vertical 180 Degree Turning Duct
Authors: Yuanwei Lu , Fangde Zhou , Yueshe Wang , Huanqun Qian , Zhihua Hu 
Published: November 2021

Abstract
Bend is applied in many industries, which exert an influence on fluid and make the flow complicate. The second flow caused by the bend is strong enough that the flow behind it very long can be affected, so it is hard to make the flow in it steady. The long-term unsteady flow can make the pipe fatigue, so make the tube crack and leak. It is important to improve this situation.
In this paper a throttle is built in the exit of the bend to control the non-homogeneous flow inside the bend, which can overcome the disadvantage of bend in industrial application.
Through computed the flow field behind the bend by water, we can see that the throttle can improve the flow situation and make the flow steady behind it. Applying this method to the gas-liquid flow, the experimental result showed that the void fraction behind the bend is alike the fully developed flow. It means that the throttle can improve the two-phase flow situation in the invert U bend.
At last the gas-liquid flow pattern in-bend was studied by experiment and built the flow pattern map in the vertical parts of the invert U bend. It was found that the flow pattern in the vertical part of invert U bend is different from the fully developed gas-liquid flow in vertical tube. The throttle built in the bend make the unsteady region of two-phase flow being reduced.
Subcooled Boiling of Surfactant Solutions
Authors: Hetsroni G. , Gurevich M. , Mosyak A. , Rozenblit R. , Yarin L. P. 
Published: November 2021

Abstract
Boiling heat transfer from horizontal stainless steel tubes, submerged in subcooled surfactant solutions of various concentrations was studied experimentally. The kinetics of boiling (bubble nucleation, growth and departure) in pure water, fresh and degraded solutions was investigated by the high speed video recording in combination with Infrared Thermography. The specific features of boiling of surfactant solutions were revealed. It was found that the subcooled nucleate boiling of surfactant could not be described by a single curve in contrast to water. At given values of heat flux and bulk temperature the heat transfer coefficient does not depend significantly on the concentrations of the solution. A boiling hysteresis was found only for degraded solutions. This phenomenon may be related to formation of a surfactant monolayer, which results in damping of an interfacial motion.
Frost Growth in Regenerative Heat Exchangers: Part I — Problem Formulation and Method of Solution
Authors: Shang W. , Chen H. , Evitts R. W. , Besant R. W. 
Published: November 2021

Abstract
In this paper the problem of frost growth within the narrow flow passages of a regenerative rotary wheel is formulated. Frost growth is assumed to occur for the portion of the wheel subject to warm humid airflow. While the wheel is subject to cold dry airflow the frost is cooled but no frost grows. This cyclic frost growth and cooling process is continued with each wheel rotation. An analytical and numerical model is developed to simulate the frost growth over one to two hours while the wheel rotates at speeds from 5 to 35 rpm.
Frost Formation and its Density Behavior on Various Surfaces
Authors: Kim Cheolhwan , Shin Jongmin , Tikhonov Alexei V. , Ha Samchul , Choi Bongjun 
Published: November 2021

Abstract
An experimental study has been conducted to investigate the effects of surface energy on frost formation. Test samples with three different surfaces of which Dynamic Contact Angles (DCA) are 23, 55 and 88 degrees are installed in a wind tunnel and exposed to a humid airflow. The thickness and the mass of frost layer are measured and used to calculate frost density while frost formation is visualized simultaneously with their measurements. Results show that frost density increases as time increases at specific test conditions. The air Reynolds number, the airflow humidity and the cold plate temperature are maintained at 12,000, 0.0042 kg/kg and −20 degrees Celsius, respectively. The surface with a lower DCA shows a higher frost density for a two-hour test, but no differences in frost density have been found after two hours of frost generation. Empirical correlations for thickness, mass and density are proposed as the functions of test time and surface energy. Visualization of frost generation was in good agreements with test results.
Heat Transfer Characteristics in Melting of Granular Packed Bed Subject to Horizontal Forced Convection
Authors: Hao Y. L. , Tao Y.-X. 
Published: November 2021

Abstract
A series of experiments are conducted to investigate the characteristics of melting and heat transfer of a packed bed consisting of melting ice particles subject to horizontal forced convection. The packing pattern of ice particles in horizontally flowing water is recorded using a digital video camcorder and a digital camera at the water velocity of 0.01, 0.05, and 0.10 m/s, respectively, and supply water temperature of 4, 10, 20, and 30 °C, respectively. The mass of ice particles is measured at the desired time interval during the meting process. The volume of packed bed is obtained based on the digital images. The time variation of average melting rate per unit bed volume and average heat transfer coefficient is determined. Within the experimental conditions, the average melting rate per unit bed volume in the packed bed in horizontally flowing water increases during convective melting. The average heat transfer coefficient decreases during convective melting. The effects of water velocity and water temperature on the melting and heat transfer in the melting process are analyzed. The original experimental data and correlations for Nusselt number based on the present results are published.
Intermolecular and Surface Forces and Their Role in Nanoscale Liquid Transport and Phase Change
Authors: Weng Jian-Gang , Tien Chang-Lin , Majumdar Arun 
Published: November 2021

Abstract
When liquid molecules interact in a highly confined region, their bulk characteristics are often overshadowed by near-field intermolecular and surface forces. These include van der Waals, electrostatic, structural, and surface tension forces. This paper will present two examples of how thermodynamic models and Molecular Dynamic simulation can provide insight into nanoscale liquid transport and phase change: liquid film stability and the curvature effect on surface tension of droplets and bubbles. Both examples have major ramifications on problems such as nucleation, condensation, boiling, biological transport etc.
Thermal Modeling of Unlooped and Looped Pulsating Heat Pipes
Authors: Shafii M. B. , Faghri Amir , Zhang Yuwen 
Published: November 2021

Abstract
Analytical models for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs are presented in this study. The governing equations are solved using an explicit finite difference scheme to predict the behavior of vapor plugs and liquid slugs. The results show that the effect of gravity on the performance of top heat mode unlooped PHP is insignificant. The effects of diameter, charge ratio, and heating wall temperature on the performance of looped and unlooped PHPs are also investigated. The results also show that heat transfer in both looped and unlooped PHPs is due mainly to the exchange of sensible heat.
Molecular Dynamics Simulation of Interfacial Tension of Ultra-Thin Liquid Films on a Solid Surface
Authors: Sinha Shashank , Freund Jonathan B. , Dhir Vijay K. 
Published: November 2021

Abstract
The effect of wall proximity on the interfacial tension of ultra-thin liquid films of Lennard-Jones (12,6) fluid has been studied using Molecular Dynamics Simulation. The wall’s presence can potentially affect drop-wise condensation and other phase change phenomena such as boiling. Initially the Lennard-Jones atoms are placed near a solid wall with FCC lattice structure in a doubly periodic box. Once equilibrated at a desired temperature, a thin liquid film forms on the solid wall. The surface tension of the liquid-vapor interface is computed statistically. When the film is thick (&gt; 40 Å), surface tension at the liquid-vapor interface is found to be unaffected by the presence of the solid wall and matches bulk values reported for Argon. However for thinner films (&lt; 15 Å), surface tension of the liquid-vapor interface deviates from the macroscopic value. This has been investigated for various temperatures ranging from the triple point to the critical point. As the film thins further (1–2 molecules thickness), the liquid-vapor interface resembles a solid-vapor interface. Surface tension of this solid-vapor interface is evaluated for a solid wall modeled both by an equivalent interacted potential and discrete atoms. The two cases are found to yield different results. The Equivalent potential for the wall gives lower surface tension and liquid density near the solid wall compared to the discrete atoms case.
Finite Element Interface-Tracking and Interface-Capturing Techniques for Flows With Moving Boundaries and Interfaces
Authors: Tezduyar Tayfun 
Published: November 2021

Abstract
We provide an overview of the interface-tracking and interface-capturing techniques we have developed in recent years for computation of flow problems with moving boundaries and interfaces, including two-fluid interfaces. The interface-tracking techniques are based on the Deforming-Spatial-Domain/Stabilized Space-Time formulation, where the mesh moves to track the interface. The interface-capturing techniques, which were developed for two-fluid flows, are based on the stabilized formulation, over non-moving meshes, of both the flow equations and the advection equation governing the time-evolution of an interface function marking the location of the interface. For interface-capturing techniques, to increase the accuracy in representing the interface, the Enhanced-Discretization Interface-Capturing Technique (EDICT) can be used to to accomplish that goal. We also provide and overview of some of the additional ideas developed to increase the scope and accuracy of these two classes of techniques.
CFD Modeling of Free Surface and Entrainment of Buoyant Particles From Free Surface for Submerged Jet Systems
Authors: Khan Md. N. H. , Fletcher Clive , Evans Geoffrey , He Qinglin 
Published: November 2021

Abstract
For a submerged jet, there are many design characteristics to explore for better mixing of buoyant particles (BP). Industries are facing difficulties in mixing of BP. Higher turbulence favors mixing [1], but mixing of BP has always been an art. Submerged jet (SJ) or impinged jet (IJ) is one of the ways to disperse BPs. For a SJ, modeling of free surface is important when the jet is not deeply submerged (∼ 10 mm) in the liquid bath. In this research project, the free surface (surface between air and liquid) for a SJ system in a cylindrical liquid bath and entrainment of BPs has been studied with CFD analysis. The solution parameters (velocity profile and center line velocity) are validated against experimental LDV data generated. The use of 2D axisymmetric geometries minimized the computational cost. To overcome the computational burden of tracking individual particles, the dispersion of particles/ turbulent fluctuations were determined by a Particle Cloud Model [2].
Instantaneous Velocity Profiles and Characteristics of Pressure-Driven Flow in Microchannels
Authors: Kawaji M. , Chung P. M.-Y. , Kawahara A. 
Published: November 2021

Abstract
This paper presents a review of the flow characteristics in microchannels and our own flow visualization work using a photochromic dye activation technique. The review reveals differences in flow behaviour between micro- and macro-channels, and the need to measure instantaneous velocity profiles to explain these differences. In the experiment, de-ionized water containing a photochromic dye was pumped through a square capillary tube with inner dimensions of 96 μm × 96 μm to yield a Reynolds number of 0.1. A pulsed ultraviolet laser beam was used to create dye traces in the flowing liquid, and images of the traces were recorded with a video camera. Friction factor in laminar flow was also determined from pressure drop measurements at several Reynolds numbers using tap water. The experimental results showed the flow in intermediate-sized microchannels at low Reynolds numbers to still conform to conventional fluid mechanics theory, possibly with slight deviation. The success in obtaining quantitative results with this approach holds promise for further studies of flows in microchannels with smaller diameters.
Controlling Drop Rebound With Solid Target Motion
Authors: Kim Ho-Young , Lee Heon Ju 
Published: November 2021

Abstract
Drops having a high surface tension and a low viscosity, such as water and molten metal drops, exhibit a vigorous recoiling and a long-lasting oscillation upon impacting with nonwetting solid surfaces. Here we report the study of controlling drop rebound using target movement. Our experimental study reveals that drop rebound is highly enhanced in such a condition that the target moves upward at the moment of impact and reverses its motion when the recoiling starts. On the other hand, an effective suppression of drop rebound is achieved by moving the target downward upon drop impact and reversing its direction well in the middle of the recoiling process. This controlling scheme of drop rebound can be employed in such practical applications as the spray deposition processes and the solder jet bumping.