bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microtube Convection Heat Transfer for a Power-Law Fluid in Laminar Slip Flow With an Isoflux Boundary Condition
Authors: Wang Meili , Ameel Tim A. , Frazier A. Bruno , Warrington Robert O. 
Published: January 2022

Abstract
An analytical solution to the problem of flow in a tube with a diameter of the same order as the mean free path of the fluid is presented. Under these conditions, the Knudsen number becomes an important parameter and the fluid may exhibit slip flow and thermal nonequilibrium at the tube walls. A power-law fluid is considered to be hydrodynamically fully developed at the tube entrance and an isoflux thermal condition is assumed. A direct solution technique is applied to the Energy Equation to determine the temperature field in the thermal entrance region of the tube as well as in the thermally fully-developed region. The direct solution technique is in contrast to an indirect method reported earlier for a Newtonian fluid only. For all values of the Knudsen number, the fully-developed Nusselt number is seen to increase with a decreasing flow index n. The increase in the fully-developed Nusselt number for a shear-thinning non-Newtonian fluid (n = 0.5) relative to that for the Newtonian fluid (n = 1) decreases from approximately 9 to 3.5 percent as the Knudsen number increases from 0 (non-slip flow) to 0.12. Thus, the slip flow and temperature jump effects tend to diminish the non-Newtonian effects as they apply to the temperature field.
A Parameter Estimation Technique for Determining Soil Thermal Properties in the Design of Heat Exchangers for Geothermal Heat Pumps
Authors: Beck James V. , Shonder John A. 
Published: January 2022

Abstract
A one-dimensional thermal model is derived to describe the temperature field around a vertical borehole heat exchanger (BHEx) for a geothermal heat pump. The inlet and outlet pipe flows are modeled as one, and an effective heat capacity is added to model the heat storage in the fluid and pipes. Parameter estimation techniques are then used to estimate various parameters associated with the model, including the thermal conductivity of the soil and of the grout which fills the borehole and surrounds the u-tube. The model is validated using test data from an experimental rig containing sand with known thermal conductivity. The estimates of the sand thermal conductivity derived from the model are found to be in good agreement with independent measurements.
Numerical Analysis of Fluid Flow and Heat Transfer in Plate-and-Frame Heat Exchangers
Authors: Sundén Bengt , Di Piazza Ivan 
Published: January 2022

Abstract
A numerical investigation of laminar and turbulent convective flow and heat transfer for single-phase flow in plate-and-frame heat exchangers is carried out. A unit cell is considered and a finite volume technique is applied for solving the governing equations. Periodic flow and heat transfer fields are assumed. For turbulence modelling the RNG k-ε model is adopted. The grid is created by using a multiblock approach and the unit cell is covered by a three-dimensional array of hexahedral control volumes in a structured body-fitted grid fashion. The Reynolds number range is from 900 to 20 000 while the Prandtl number is set to 4.33 corresponding to water at an average temperature of 40°C. The agreement between the numerical results and available experimental data is decent and encouraging. The details of the flow and temperature fields achieved by the numerical solutions, improved the understanding of the transport processes of heat and momentum.
Effect of Inlet Header Pre-Heating on the Temperature Distribution in a Steam Furnace Tube Bank
Authors: Botros Kamal K. , Weiss Marvin H. , Price Glenn R. 
Published: January 2022

Abstract
Steam furnaces encountered in chemical and power generation plants often experience a maldistribution of steam temperature at furnace tube outlets despite attempts to ensure good flow distribution in these tubes from the inlet feed header. An investigation of an existing tube bank configuration was carried out utilizing field measurements, a CFD analysis of the thermal/flow field, flow experiments with a 1:7 scale laboratory model using air as the working fluid, and a 1-D analysis of the temperature/flow distribution. The results indicate that although the inlet header does not actually run through the furnace, heat transfer by conduction from the tube walls to the inlet header wall causes preheating of the incoming steam, resulting in a substantial increase in steam temperature towards the end of the header. This steam temperature maldistribution at the inlet to the tubes persists along the tubes and manifests itself as a similar maldistribution in the tube skin wall temperatures. The latter has an impact on the system integrity if the skin wall temperature exceeds the metallurgical limit of the tube material used.
The Convective Transport Phenomena Over a Turbine Blade Near the Endwall Region With and Without Film Cooling
Authors: Miao Jr-Ming , Chen Ping-Hei 
Published: January 2022

Abstract
The present study aims to investigate the film cooling effect on the local mass transfer distributions on both suction and pressure surfaces near the endwall region of a showerhead film-cooled turbine blade by employing the naphthalene sublimation technique. The mass transfer measurements are also conducted with a smooth turbine blade for comparison. For film-cooled blade, there are three rows of injection holes staggered at the leading edge of test blade. Each row consists of seven equally spaced injection holes at a ratio of pitch to diameter equals 3. The inclined angles of injection hole are 90 degrees to the streamwise direction and 30 degrees to spanwise direction. The closest distance from the center of injection hole located on the front stagnation line to the endwall is just one pitch of hole. Experiments are conducted over a six-blade planar cascade in an open-type wind tunnel with mainstream turbulence level of 0.4%, inlet boundary layer momentum thickness of 0.955 and shape factor of 1.355. For all measurements, the exit Reynolds number is kept at a constant value of 397,000 and the blowing ratio is 0.8.
Close to the endwall the local mass transfer rate over both surfaces of the tested smooth turbine blade is much higher than that in the two-dimensional flow region. Measured results indicate that the vortex system on the suction side of tested smooth blade consists of a leading edge corner vortex, a suction leg of horseshoe vortex, a suction side corner vortex, a passage vortex and the wall vortex induced by the strong passage vortex. Downstream of S/C ≈ 0.431, the passage vortex and the wall vortex become dominant. On the pressure side of smooth turbine blade, the leading edge corner vortex, the pressure leg of horseshoe vortex and the pressure corner vortex are still visible but they all are swept out from the blade surface by the secondary flows at Sp/C ≈ 0.256.
The presence of film cooling has little influence on the leading edge corner vortex and suction side corner vortex but results in a later induction of comer vortex on pressure side compared to that without film cooling. Instead of a three-peak vortex system, the impact location of the passage vortex occurs far downstream. Therefore, the wall vortices induced by passage vortex that might be observed from smooth blade vanished in the mid-curvature portions of suction side of film-cooled blade. In addition, the ejected flows hold the leading edge comer vortex and the pressure side corner vortex on the pressure side of film-cooled blade.
Measurements of Aerodynamic Penalties Associated With Film Cooling
Authors: Burd Steven W. , Oke Rohit A. , Simon Terrence W. 
Published: January 2022

Abstract
Film cooling in gas turbine engine designs has shown great benefit over the years. Film cooling flows perturb the boundary layer flow, however, as they emerge from discrete holes. The impact on aerodynamics is experimentally evaluated for both streamwise and lateral film cooling injection. Injection is with a hole length-to-diameter ratio of 2.3 and a 35° angle of inclination. Data for two coolant-to-freestream momentum flux ratios, 0.25 and 1.0, with a high freestream turbulence intensity of 11.3% are given. Comparisons are made to similar cases without coolant injection. Evaluation is in terms of momentum thickness, shape factor, and skin friction coefficient distributions. Turbulence data are also provided. The injection geometry and coolant-to-freestream momentum flux ratio are shown to greatly influence aerodynamic penalties. Lateral injection imposes more losses, but lower skin friction values, than does streamwise injection. In some instances, the emerging coolant is capable of energizing the boundary layer, reducing losses relative to those present without coolant injection.
Enhanced Heat Transfer Charateristics of a Chevron Plate Heat Exchanger for Viscous Fluid Thermal Processing Applications
Authors: Muley Arun , Manglik Raj M. 
Published: January 2022

Abstract
Steady-state heat transfer and pressure drop data are presented for single-phase viscous fluid flows (2 ≤ Re ≤ 400) in a plate heat exchanger (PHE) with chevron plates. With vegetable oil as test fluid (130 &lt; Pr &lt; 290), the data are for three different plate arrangements, two symmetric (β = 30°/30° and 60°/60°) and one mixed (β = 30°/60°), in a single-pass, U-type, counter-flow PHE. The effects of chevron angle β, and flow conditions (Re, Pr, μ/μw) on Nu and f characteristics of the PHE are investigated. Depending upon β and Re, up to 3 times higher Nu are obtained in chevron plates compared to an equivalent flat-plate channel, though the corresponding f are also up to 6.6 times higher. Comparisons of these data with previously reported Nu and f results highlight the complex influence of chevron plate surface corrugations. Also, relative to equivalent flat-plate packs, chevron plates sustain up to 2.9 times higher heat transfer rates on a fixed geometry and constant pumping power basis, and require up to 48% less surface area for the fixed heat load and pressure drop constraint.
Experimental and 2-D Numerical Studies on Micro-Scale Bending of Stainless Steel With Pulsed Laser
Authors: Chen Guofei , Xu Xianfan , Poon Chie C. , Tam Andrew C. 
Published: January 2022

Abstract
Laser forming or laser bending is a newly developed, flexible technique which modifies the curvature of sheet metal by thermal residual stresses instead of external forces. The process is influenced by many parameters such as laser parameters, material properties and specimen dimensions. In this work, a pulsed Nd:YLF laser was used as the energy source. The laser beam was focused into a line shape irradiating on the stainless steel specimen to induce bending. The bending angle was measured at various processing conditions. A finite element analysis was performed with the use of a 2-D plane strain model to simulate the temperature field and the thermo-elasto-plastic deformation process. Experimental measurement and computational results were in good agreement. Numerical sensitivity studies were performed to evaluate the effects of the unavailable material property data at high temperature. It was found that both optical reflectivity and thermal expansion coefficient influenced the bending angle significantly, while other extrapolated material properties at high temperatures yielded acceptable results.
Interfacial Phase Growth in Metal Matrix Composites
Authors: Chen J. K. , Beraun J. E. , Tzou D. Y. 
Published: January 2022

Abstract
The time dependence of a reinforcement-matrix interfacial layer growth (RMILG) in most metal matrix composites (MMCs) is not t1/2 as described by Fick’s diffusion law. Moreover, the RMILG versus t1/2 could be linear for relatively short and long times, and an anomalous transition behavior exhibits in between. In this paper a dual-phase-lag diffusion (DPLD) model, extending from Fick’s diffusion law, is proposed to characterize the RMILG kinetics. It accounts for two lagging times required for the interdiffusion process between dissimilar materials and the chemical reaction that forms an interfacial compound. This inclusion of the lagging times uniquely represents the four types of growth kinetics and can capture multiple-stage response over the entire RMILG history. Numerical results show that the DPLD modeling agrees very well with experimental data.
Modeling of Fluid Flow and Heat Transfer in a Hydrothermal Crystal Growth System: Use of Fluid-Superposed Porous Layer Theory
Authors: Chen Q.-S. , Prasad V. , Chatterjee A. 
Published: January 2022

Abstract
Hydrothermal synthesis, which uses aqueous solvents under high pressure and relatively low temperature, is an important technique for the growth of crystalline materials such as quartz, bismuth silicate and various kinds of oxides, all of which are difficult to grow. A hydrothermal growth system usually consists of finely divided particles of the nutrient, predetermined volume of a solvent and a suitably oriented crystal seed (Fig. 1) under very high pressures, generally several thousand psi. The nutrient dissolves at a higher temperature in the lower region, moves to the upper region due to buoyancy-induced convective flows and deposits on the seed due to lower solubility if the seed region is maintained at a lower temperature. The system can be modeled as a composite fluid and porous layer using the Darcy-Brinkman-Forchheimer flow model in the porous bed. Since the growth process is very slow, the process can be considered quasi-steady and the effect of dissolution and growth can be neglected. This first study on transport phenomena in a hydrothermal system therefore focuses on the flow and temperature fields without the presence of the seed and mass transfer. A three-dimensional algorithm based on the curvilinear finite volume technique and a non-staggered grid layout has been developed to simulate the flow and heat transfer in a typical autoclave system. An axisymmetric flow pattern at low Grashof numbers and three dimensional flow pattern at high Grashof numbers are predicted. The study is also extended to study the onset of oscillatory flow with a variation in the porous bed height. These results, for the first time, depict the possible flow patterns in a hydrothermal system, that can have far reaching consequences on the growth process and crystal quality.
Substrate Melting and Resolidification After Contact With a Molten Layer of High Melting Point Material
Authors: Wang S.-P. , Wang G.-X. , Matthys E. F. 
Published: January 2022

Abstract
High-melting-point metals and their alloys have wide use as coating materials because of their improved properties. A good understanding of the bonding mechanism between the coating layer and the substrate is therefore a very important concern in thermal spray processing of these high-melting-point materials. In this work we have conducted a numerical study of the cooling and solidification of such materials, and in particular of the substrate melting and resolidification phenomena for a substrate impacted by a high melting point droplet. A model has been developed and a non-dimensional analysis led to the identification of the independent non-dimensional parameters controlling the process. The critical conditions needed for substrate melting in the case of given pairs of deposit and substrate materials were quantified, and are presented in terms of non-dimensional operational maps of wide applicability. Information on the critical conditions under which the substrate surface melts, and on the maximum melting depth achieved into the substrate was also generated for various process parameters including deposit undercooling, initial substrate temperature, variations in interfacial heat transfer coefficient, and others.
Depth of Thermal Penetration in the Fast Transient Process of Heat Transport
Authors: Tzou D. Y. , Chiu Kevin K. S. , Beraun Jorge E. , Chen J. K. 
Published: January 2022

Abstract
This work studies the depth of thermal penetration in the fast-transient process of heat transport, with emphasis on the rapid evolution of heat affected zone that reflects the combined behavior of thermalization and relaxation during the short-time transient. Employing the dual-phase-lag model, the heat balance integral is derived that contains both the phase lag of the heat flux vector (reflecting the relaxation behavior) and the phase lag of the temperature gradient (reflecting the thermalization behavior). The early-time responses where both phase lags are strong functions of temperature are modeled in detail, which emphasize the ways in which the classical diffusion behavior is retrieved as the thermalization and relaxation behaviors gradually diminish in the time-history. It shows that the classical diffusion model assuming Fourier’s law does not provide a conservative estimate for the response of temperature in the thermal process zone, which may result in unexpected early-time failure of conductors if not properly controlled. From a microscopic point of view, these unexpected factors are interpreted in terms of the microscopic parameters, including the coupling factor in phonon-electron interactions (for metallic structure) and the umklapp and normal relaxation times in phonon scattering (for semiconductors and insulators.
Investigation of Induced Thermal and Fluid Transport Phenomena in Laser Assisted Chemical Vapor Deposition
Authors: Yu D. , Duncan A. B. 
Published: January 2022

Abstract
Laser-assisted Chemical Vapor Deposition (LCVD) utilizes a focused laser beam to induce a chemical vapor deposition process upon a substrate material. By moving either the substrate or the focal plane of the laser beam LCVD may be used to produce three dimensional structures having characteristic lengths on the order of μm. The physical phenomena associated with LCVD also occur on length scales of μm. For this reason, with the exception of the observation of bulk properties, detailed experimental observations of the fluid flow and heat transfer phenomena associated with the LCVD process do not exist. The LCVD process is characterized by the inter-relating fluid flow, chemical reaction and mass and heat transfer phenomena. In addition, the characteristics of the laser and the deposited material morphology influence the overall process.
The current research effort has developed a mathematical model and employed a numerical technique to characterize the three-dimensional natural convection induced by an incident laser beam around a fiber. This effort has not accounted for the effects of the chemical reactions associated with the LCVD process. The laser irradiance characteristics and the absorption by the fiber material have been incorporated into the energy equation. The velocity and temperature profiles in the boundary layer demonstrate the existence of a small area in which large temperature gradients and a chemical reaction occur. This effort has laid the foundation for an investigation of the one-dimensional diffusion controlled chemical vapor deposition process model. Additionally, it will facilitate the modeling of the three-dimensional homogeneous and heterogeneous reactions in the buoyancy driven flow produced in LCVD fiber formation.
Molecular Dynamics Study of Solid Thin-Film Thermal Conductivity
Authors: Lukes Jennifer R. , Liang Xin-Gang , Tien Chang-Lin 
Published: January 2022

Abstract
This study explores the feasibility of using the molecular dynamics computational technique to predict the thermal conductivity of solid thin films in the direction perpendicular to the film plane. The results show that thermal conductivity, as expected from thin-film experimental data and theoretical predictions, decreases as film thickness is reduced. In the large-size limit, this method yields thermal conductivities which asymptote to a value comparable to experimental data. The calculations modestly overpredict thermal conductivity, probably due to the use of a too-steep intermolecular potential. Most interestingly, an unusual wave effect is revealed for thin film thermal conductivity. This effect may be a manifestation of phonon wave interference analogous to the interference of light which determines the radiative properties of thin films.
It is also found that there are some temperature and computational domain size limitations on the applicability of molecular dynamics to the study of solid systems. A regime map is developed which delineates the conditions necessary for molecular dynamics to produce physically meaningful results. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of solid thin films. More generally, this work demonstrates the potential of molecular dynamics for ascertaining microscale thermophysical properties in more complex structures.
Heat Transfer and Solidification Model for a Droplet Impinging on a Solid Substrate
Authors: Canton A. , Delplanque J.-R. , Rangel R. H. 
Published: January 2022

Abstract
Spray deposition is an efficient means of manufacturing materials. It requires fewer manufacturing steps than conventional methods, saves energy, and reduces costs. Various experimental and theoretical studies have been conducted to investigate spray deposition processes. They generally focus on the fluid dynamics and/or heat transfer aspects of these processes. The effort discussed herein is dedicated to including a thermal solver into an existing Navier-Stokes solver for free surface flows (RIPPLE) in order to allow detailed numerical simulations of droplet impact, spreading, and solidification. The new model solves the thermal energy equation over the complete domain (droplet and substrate) using the enthalpy method. The enthalpy method is preferred to a temperature formulation because it does not require the tracking of the solid/liquid interface during the solidification process. The numerical procedure developed to this end is described herein, and test cases (with and without solidification) are presented.
Inverse Heat Conduction Problems and Generalisation of Experimental Results
Authors: Raudenský Miroslav , Druckmüller Miloslav , Horský Jaroslav 
Published: January 2022

Abstract
The paper describes the process of data evaluation for the experimental study of cooling by means of water and mist jets. The relative movement of nozzles and the cooled surface are characteristic of these experiments. The speed of movement and the relative position of the nozzle to the cooled surface are additional parameters to the standard thermal parameters. Two types of experiments are mentioned. Both are based on the same principle — a hot steel plate is cooled, temperature in several points of the plate is measured by embedded thermocouples and the temperature records are evaluated by an inverse heat conduction task. Using these results in mathematical models shows certain disadvantages. The data are influenced by noise from both the thermal and the spatial point of view. The data are rare in certain surface temperature areas due to the fast temperature changes during the quenching process. A numerical interpolating procedure has been developed to compute the general parameters describing the cooling and to reduce the amount of the experimental data.