bluuebunny/crossref_metadata_2025_split huggingface dataset:
Swirling Effect on Thermal-Fluid Transport Phenomena in a Strongly Heated Concentric Annulus
Authors: Torii Shuichi , Yang Wen-Jei 
Published: November 2021

Abstract
A numerical study is performed to investigate thermal transport phenomena in circular Couette flow in a concentric annulus, in which an axially rotating inner cylinder and stationary outer cylinder are strongly heated under the same heat flux condition. The anisotropic t 2 ¯ - ε t heat-transfer model together with the anisotropic k-ε turbulence model is employed to determine thermal eddy diffusivity. When the inner cylinder is at rest, the turbulent kinetic energy and temperature variance substantially diminish over the whole annular cross-section along the flow, resulting in laminarization, i.e., a deterioration in heat-transfer performance at the inner and outer cylinder walls. In contrast, a substantial reduction in the turbulent kinetic energy and temperature variance in the laminarizing flow is suppressed in the presence of inner core rotation. In other words, inner core rotation contributes to the suppression of laminarization in a strongly heated gas flow. These characteristics in thermal fluid flow with temperature-dependent thermal property are summarized in the form of dimensionless heat flux parameter versus inlet Reynolds number with the Taylor number, as the parameter.
Chracteristics of Dehumidifying Fin and Tube Heat Exchangers for Various Wettability Surfaces
Authors: Ahn S. P. , Lee H. U. , Ha S. C. 
Published: November 2021

Abstract
Generally, the air-side pressure drop is known to be dependent on the wetting surface of fin and tube heat exchanger (coil) in an air-conditioning system. Filmwise condensation occurs in good hydrophilic surface having a smaller contact angle on the fin. Thus, many hydrophilic coated materials were developed and applied to heat exchangers to decrease pressure drop in wet condition. This experimental study investigated the characteristics of dehumidifying fin and tube heat exchangers for various wetting surfaces and durabilities. This study proposed that the air-side wet/dry pressure drop ratio (ΔPwet/ΔPdry) can be correlated with the advancing dynamic contact angle and the water droplet diameter. Also, the heat exchangers were accelerated with 200 cycles in which they were dipped into distilled water for 60 minutes and dried with a fan for another 60 minutes consecutively for evaluating the wetting durability performance.
A Microdevice for Measuring Thermophysical Properties of Nanowires and Nanotubes
Authors: Shi Li , Kim Philip , McEuen Paul L. , Majumdar Arunava 
Published: November 2021

Abstract
Nonotubes and nanowires are expected to have interesting thermophysical properties. For example, unusually high thermal conductivity and possibly low-temperature quantized thermal conductance have been predicted for carbon nanotubes (Berber et al. 2000). Meanwhile, other nanowires, such as Bi wires, may have suppressed thermal conductivity and high thermoelectric figure of merit (Volz and Chen). However, there lacks of experimental proof of these predictions because there are no established methods to measure the thermophysical properties of nanotubes and nanowires. Up to date, there are very few measurement data of thermal properties of nanotubes as well as nanowires (Hone et al. 1998, 1999, and 2000; Mizel et al., 1999). To provide a platform for concurrently measuring thermal conductivity and Seebeck coefficient of nanotubes and nanowires, a microdevice has been designed and used for measuring multiwall carbon nanotubes (MWCNs). Figure 1 shows the scanning electron micrographs of the microdevice. The device is a suspended structure consisting of two adjacent 10 μm × 10 μm silicon nitride (SiNx) membranes or islands suspended with three (or four) 200-μm long and 2 μm wide silicon nitride beams. One 30 nm thick, 200 nm wide, and 150 μm long platinum (Pt) heater/thermometer coil was built on each island. The heater coil is connected to contact pads with 200 μm long and 1μm wide Pt lines.
Two-Dimensional Nanoscale Heat Conduction Using Ballistic-Diffusive Equations
Authors: Yang Ronggui , Chen Gang 
Published: November 2021

Abstract
It is well recognized that heat conduction in micro- and nanoscale and in ultrafast processes may deviate from the predictions of the Fourier law, due to boundary and interface scattering and the finite relaxation time of heat carriers. The Boltzmann equation is often used with the relaxation time approximation to study classical size effect. However, the solution of Boltzmann equation has been limited to few simple geometrical configurations such as thin films and superlattices. In this paper, we apply the transient ballistic-diffusive equation (BDE) to study the two-dimensional nonlocal phonon transport phenomena. The numerical calculation strategies developed in this paper can be promising for incorporating into commercial device simulator.
Rotation of Laser Opto-Microactuator With Low-Heat-Conductivity Material
Authors: Ota Masahiro , Noguchi Atsunobu 
Published: November 2021

Abstract
A laser opto-microactuator with four flat blades made of aluminum or Pyrex glass plates is proposed in this paper. The effects of the heat conductivity of the actuator materials on rotation phenomena are discussed. Through molecular gas dynamics effects, the actuator is rotated upon irradiation by an argon-ion laser beam. The blade surfaces of the actuator were coated with carbon black powder to absorb laser beam power and heat the surfaces. Three kinds of blades, noncoated, single-side-coated and both-sides-coated blades, were manufactured.
The rotation rate of the actuator with both surfaces of one blade coated with the powder is faster than that of the actuator with only one surface coated with the powder because the total amount of radiation from the both-sides-coated surface is greater than that of a single-side-coated surface.
Compressible Gas Flow Through Smooth and Rough Microchannels
Authors: Turner Stephen E. , Gregory Otto J. 
Published: November 2021

Abstract
This paper presents an experimental investigation on compressible gas flow through microchannels with a constant area, rectangular cross-section. The microchannels are etched into silicon wafers, capped with smooth glass, and have hydraulic diameters between 4 and 100 μm. All measurements were made in the laminar flow regime with Reynolds numbers ranging from 0.02 to 1000. Smooth channels were obtained by etching (100) silicon wafers with potassium hydroxide (KOH) solution. Rough channel surfaces were obtained by etching (110) silicon wafers with KOH. The investigation shows that the friction factor for both smooth and rough microchannels compares closely with continuum theory.
Analytical Investigation of the Effect of Thermal Dispersion on Forced Convection in Heterogeneous Porous Media
Authors: Kuznetsov A. V. 
Published: November 2021

Abstract
This paper presents a new analytical solution of a problem of forced convection in a heterogeneous channel filled with two different layers of isotropic porous media. The Brinkman-Forchheimer-extended Darcy equation is utilized to describe the fluid flow in the porous layers, and the effect of transverse thermal dispersion is accounted for in the energy equations. Three momentum boundary layers are identified in the channel: a boundary layer at the solid wall and two boundary layers at the interface between the porous media. The dependence of the Nusselt number on the Darcy numbers, Forchheimer coefficients, and particle Reynolds numbers in different parts of the channel is investigated. This study demonstrates that thermal dispersion has a strong effect on the Nusselt number in the channel for large particle Reynolds numbers.
Numerical Simulation for the Process of Recovery of a Planar Reservoir With Non-Newtonian Petroleum
Authors: Zhu Zuojin , Wu Qingsong , Gao Chunfu 
Published: November 2021

Abstract
The numerical simulation has been carried out for the process of the recovery of a reservoir with non-Newtonian Petroleum in terms of the stablized bi-conjugate gradient approach. To propose the governing equations for the problem on hand, the traditional Darcy law for flow in porous media is used to describe the flow behavior of water as the driving fluid, and the rheological relation for the so-called Bingham fluid is employed to describe the flow behavior of the driven non-Newtonian petroleum. The pressure potential and the water saturation are used as the primary variables. The two phase fluids system is considered to be a subsurface immiscible and micro compressible one. The solutions of the transient planar two phase flow problem in porous media have been sought with the corresponding outer and inner boundary conditions. The finite difference scheme has been used to approximate the governing equations for the problem considered. To keep the approximation physically effective, the upwind weighted treatment for the relative permeability at mesh surface is provided. Newton-Raphson iteration is used in view of the existence of non-linearity. And finally, the stablized bi-conjugate gradient approach is applied to seek the solutions of the corresponding algebraic equations required. A good agreement is obtained between the results of non-Newtonian model and production data, but results of the Newtonian model were unable to yield good agreement with the data.
Forced Convection in a Channel Limited by Permeable Boundaries
Authors: Segrilo Leonardo M. , Martins-Costa Maria Laura 
Published: November 2021

Abstract
A mixture theory model is employed in a local description of the energy transfer in a channel with permeable boundaries which is simulated by considering two distinct flow regions, one consisting of a Newtonian incompressible fluid and the other represented by a binary (solid-fluid) mixture. Compatibility conditions at the interface (pure fluid-mixture) for momentum and energy transfer are considered. The simulations are carried out by using an iterative procedure with a finite difference approach, in which the fluid (in the pure fluid region) and the fluid constituent (in the mixture region) inlet temperatures are the only boundary conditions prescribed on the flow direction.
Some New Approaches to Bubble Plume Modelling Using CFD
Authors: Milelli Massimo , Smith Brian L. , Lakehal Djamel 
Published: November 2021

Abstract
The paper describes some advancements made in using Computational Fluid Dynamics (CFD) techniques in a generic study of venting of gases to liquid pools. The work focusses on the role played by turbulence in promoting pool mixing and, in particular, explores the application of Large Eddy Simulation (LES) methodology to capture bubble-induced turbulence effects. In the first part of the paper, a study is reported involving two-dimensional simulations of a simple, vertical shear layer containing bubbles for which some turbulence data are available from experiments. This work demonstrates particularly the importance of grid size, and its relation to the ratio of the cut-off filter to the bubble diameter. Optimum model parameters derived from this study are then used in a three-dimesional simulation of a free bubble plume, for which the flow is buoyancy-driven rather than shear-induced. Points of similarity (and difference) between the two analyses are discussed and some general conclusions drawn regarding the applicability of using LES techniques for this class of flow.
Experimental Verification of the Performance of a Droplet Injection System for Use in a Rod Bundle Test Facility
Authors: Ireland A. J. , Rosal E. , Hochreiter L. E. , Cheung F. B. 
Published: November 2021

Abstract
A droplet injection system has been developed for use in a rod bundle heat transfer test facility designed specifically for the study of dispersed flow film boiling during reflood transients in a nuclear reactor. Three different injectors having various pitch configurations and hole patterns were tested. The drop field produced by each was characterized using a laser-assisted size measurement technique. Appropriate mean diameter and drop size distributions that closely simulate the drop field encountered in a reactor bundle assembly under reflood conditions was obtained. The drop injection system developed can readily be employed in the rod bundle test facility to investigate the droplet heat transfer in the dispersed flow film boiling regime.
A Fully-Coupled Transient Model for Predicting Interface Contamination in Product Pipelines
Authors: de Freitas Rachid Felipe Bastos , Carneiro de Araujo José Henrique , Baptista Renan Martins 
Published: November 2021

Abstract
This work presents a coupled fluid transient model to describe the mixing phenomenon arising in batch transfers in petroleum pipelines. The concentration evolution described by the dispersion of matter at the products’ interface is properly taken into account on the mass and momentum balance equations for the mixture as a whole. The resulting mathematical problem is formed by a system of non-linear partial differential equations which is solved by means of an operator splitting technique, combined with a Glimm’s scheme and predictor-corrector method. The influence of stopping the line during a batch transfer on the mixing volume is preliminarily analyzed for a particular batch.
Modeling the Cooling Process Path of a Dehumidifying Coil Under Frosting Conditions
Authors: Mago P. J. , Sherif S. A. 
Published: November 2021

Abstract
Whenever humid air comes in contact with a cooling coil whose temperature is below both the dew-point of water vapor in air and the freezing point, frost will form. The nature of the frost forming on the coil will depend to a large measure on the psychrometric conditions prevailing inside the freezer and whether the air around the coil is subsaturated or supersaturated. Psychrometric theory and the apparatus-dew-point calculating procedure assume that the cooling process path as the air passes through the coil is a straight-line on the psychrometric chart. The actual path is however a result of a much more complex series of processes and is therefore a curve. While researchers have calculated the actual process path on a dehumidifying coil, none has attempted to do the same for a frosted, multi-row coil. It is believed that determining the actual conditions leaving a given row in a multi-row freezer coil is a crucial step in identifying the coil location in the vicinity of which the transformation from the subsaturated zone to the supersaturated zone occurs. This will prove a key step in identifying a demarcation line between the unfavorable snow-like frost and the more traditional (and more favorable) frost formation patterns. Thus the objective of this paper is to calculate the cooling process path in an actual industrial-size finned-tube, multi-row coil utilizing experimentally derived data and correlate the shape of the path with the prevailing psychrometric conditions in the freezer in the hope of identifying the demarcation line in question. The latter will be determined analytically and confirmed experimentally.
On Measuring Bubble Nucleation Temperature of Water/Methanol Mixtures Using Ink-Jet Printer Technology
Authors: Avedisian C. T. , Osborne W. S. , McLeod F. D. 
Published: November 2021

Abstract
The bubble nucleation temperature of water/methanol mixtures is measured using the fast transient process of thermal ink-jet printer technology. The heater element is placed in a dynamic bridge circuit coupled with an instrumentation amplifier to measure the change in resistance of the heater as a programmed voltage is applied across the bridge. An inflection point in the evolution of resistance signals bubble nucleation. A separate calibration relates resistance to average heater temperature.
The results show that the nucleation temperature increases as the power input to the bridge increases for a given concentration. The heating rates are extremely high, in some cases reaching over a quarter billion degrees per second. As methanol concentration increases, the nucleation temperature decreases. It was difficult to measure the nucleation temperature at high methanol dilution because the difference between liquid and vapor thermal conductivity decreases as methanol concentration increases for a given temperature. The nucleation temperatures are successfully correlated with a generalized corresponding states theory.
An Integrated Macro- and Micro-Scale Model for Detached Solidification in a Bridgman Growth System
Authors: Zhang H. , Larson D. J. , Chen T. H. , Xu J. 
Published: November 2021

Abstract
Prior space experiments have suggested that the defect (twin and dislocation) density can be dramatically reduced if the crystal is grown without wall contact. Techniques have been proposed to promote wall detachment during solidification by Larson, Duffar, and Wilcox. In this paper, we adopt an ampoule with a soft-finned carbon inner wall, which can arrange for growth essentially free from wall contact. An integrated numerical model for detached solidification has been developed to combine a global heat transfer model of a Bridgman system with a meniscus model near the wall. The global model accounts for heat transfer in a multiphase system (solid, liquid and gas), convection in the melt, and interface dynamics. The meniscus model accounts for meniscus dynamics over a finned structure, and a force balance at the three-phase boundary. The effects of the finned carbon wall on the temperature gradients and the interface shape will be investigated. The integrated model will be used to design apparatus and find the optimal geometry for detached solidification of CdTe growth in space and on the ground.
Micropumping by Electrowetting
Authors: Kim Chang-Jin “CJ” 
Published: November 2021

Abstract
This paper introduces the recent effort to use surface tension in MEMS, especially, to use electrowetting for efficient pumping in microfluidics. Importance of surface tension in microscale is explained, and examples of utilizing it to design microdevices are presented. Development of several devices employing different types of electrowetting is explained. Empowered by the efficient pumping by electrowetting microactuation, a programmable digital microfluidic circuit chip is proposed.
Mass Quality, Void Fraction, and Slip Ratio in Bulk Flow Boiling
Authors: Collado Francisco J. 
Published: November 2021

Abstract
New general, multidimensional transport equations for two-phase flow have been recently proposed by the author. The new theory is based on a quite simple idea namely, if the phases have different velocities, it is impossible that they cover the same distance in the same time. From this quite different point of view, new mass and energy balances for one-dimensional, steady, two-phase flow have been already presented. In this paper, after briefly reviewing the key points of the new balances, the prediction of the vapor-liquid velocity ratio (the slip) and the vapor void fraction for bulk flow boiling is analyzed with the help of the new approach. The new expressions are well compared with the bulk flow boiling data for a horizontal pipe from the Cambridge Project.
Numerical Simulation of Capillary-Tube Behaviour Working With Pure and Mixed Refrigerants Under Adiabatic and Non-Adiabatic Flow Conditions
Authors: García-Valladares O. , Pérez-Segarra C. D. , Oliva A. 
Published: November 2021

Abstract
A detailed numerical method for analysing the thermal and fluid-dynamic behaviour of capillary tube expansion devices working with pure refrigerants and mixtures has been developed by means of a one-dimensional analysis of the governing equations (continuity, momentum and energy). Metastable both liquid and two-phase regions have been taken into account.
The discretized governing equations are coupled using an implicit step by step method. In order to minimise computational cost, a special treatment has been implemented to solve the control volume that contains transition between regions and a special mesh distribution has been used. All the flow variables together with the thermophysical properties are evaluated at each point of the grid in which the domain is discretized. The numerical model allows analysis of aspects such as geometry, type of fluid, critical or non-critical flow conditions, metastable regions, adiabatic or non-adiabatic capillary tubes and transient aspects.
The accuracy of the detailed simulation model is demonstrated by comparison with experimental data from the technical literature for adiabatic capillary tubes and also for concentric capillary tube-suction line heat exchanger.
The Run-off Condition for the Non-Newtonian Rimming Flow
Authors: Fomin Sergei , Harkin-Jones Eileen , Watterson John , Raghunathan S. 
Published: November 2021

Abstract
Rimming flow on the inner surface of a horizontal rotating cylinder is investigated. Using a scale analysis, a theoretical description is obtained for steady-state non-Newtonian flow. Simple lubrication theory is applied since the Reynolds number is small and liquid film thin. Since the Deborah number is very small the flow is viscometric. The Weissenberg number, which characterizes the shear-thinning effect, maybe small or large. A general constitutive law for this kind of flow requires only a single function relating shear stress and shear rate that corresponds to a generalized Newtonian liquid. For this case the run-off condition for rimming flow is derived. Provided the run-off condition is satisfied, the existence of a continuous steady-state solution is proved. The rheological models, which show Newtonian behaviour at low shear rates with transition to power-law shear thinning at moderate shear rates, are considered. Numerical results are carried out for the Carreau and Ellis models, which exhibit the Newtonian behaviour near the free surface and power-law behaviour near the wall of the rotating cylinder.
Shape Factor in the Latent-Heat-Thermal-Energy-Storage Systems
Authors: Fomin Sergei 
Published: November 2021

Abstract
An approximate mathematical model of contact melting of an unfixed material in an elliptical capsule is developed. The main characteristic scales and non-dimensional parameters, which describe the principal features of the melting process, are found. Choosing the special heat flux distribution on the wall of the capsule allows us to derive a closed-form evolution equation for the motion of the solid, which also determines the melting rate. It is shown that the melting rate depends on the shape of the capsule. The elliptical capsules show higher rate of melting than the circular ones. The vertically elongated capsules provide more effective melting than the horizontally elongated ones, even though they have the same aspect ratio and vertical cross-sectional areas. The time required for complete melting can be achieved by the right choice of the shape of the capsule, which is specified by the value of the aspect ratio. This is especially important for the design of practical latent-heat-thermal-energy-storage systems.
The Effect of Run-Out on Design for Manufacturing in Micro-Machining Process
Authors: Lee Kiha , Ahn Sung-Hoon , Dornfeld David A. , Wright Paul K. 
Published: November 2021

Abstract
Micro-machining by mechanical machine tool, or micro mechanical machining, is an emerging fabrication technology that broadens applicable material ranges including metals and plastics. One of the problems in this micro machining, however, is relatively large run-out which is comparable to the diameter of tools. A series of experiments were conducted to identify Total Indicator Reading (TIR) and dynamic run-out of micro-machining on aluminum workpieces. Results presented in this paper indicate the ratio of run-out to tool diameter ranged between 2.2% and 10%. To compensate for the run-out in the design stage of micro features, a Java-based Design for Manufacturing (DFM) tool was developed. This tool can assist designers to design micro channels accurately considering the effect of run-out. Furthermore, the feasibility of micro-injection molding was examined with micro-machined channels. Micro-molded parts were made from ABS plastic showing negligible shrinkage from the molding process.