bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on Forced-Convective Film-Boiling Heat Transfer: Effects of Liquid Flow on a State of Vapor Film Flow
Authors: Sasaki Hidemasa , Ohtake Hiroyasu , Koizumi Yasuo 
Published: March 2022

Abstract
Focusing on the effects of a liquid velocity and subcooling, in this study the foced-convective film-boiling heat transfer was examined experimentally and analytically. Quenching tests of a vertical-long-thick cylindrical pipe were conducted for subcooled R-113 liquid in a range of bulk-liquid velocities from 0.018 to 0.081 m/s at a pressure of 0.1 MPa. The test section made of pure copper was 50, 15 and 110 mm in outer diameter, thickness and height, respectively. The test section was inserted into a transparent Pyrex glass pipe concentrically, and an annular flow passage was formed between the glass pipe and the test section.
Measured heat transfer coefficients were higher than those predicted with the two-phase boundary layer theory even in a low liquid velocity region. The characteristics of the measured heat transfer coefficients were quite similar to those of the pool film boiling. The vapor-film-unit model developed for the natural-convective film boiling was extended and applied to the present conditions. In the model, the Kelvin-Helmholtz instability wave length was used to give the length scale of the unit. The model provided good agreement with the experimental results.
Microscopic Study on Heat Transfer and Thermophysical Properties of Composite Material
Authors: Nakabeppu Osamu , Igeta Masanobu , Hijikata Kunio 
Published: March 2022

Abstract
Microscale thermal measurement by the atomic force microscope (AFM) with a thermocouple probe has been investigated. Temperature distribution measurement of a small heater and thermal visualization of a composite material, carbon fiber reinforced plastic (CFRP), were conducted with controlling an ambient air pressure. In the temperature measurement, it has been shown a temperature image is affected by heat conduction through the ambient air in a spatial resolution and contrast. The performance is evaluated at 30 μm spatial resolution in a high contrast image under the atmospheric pressure condition, while less than 1 μm resolution in a noisy image under the low pressure condition. In the microscale thermal characteristics measurement, carbon fiber and epoxy resin in the CFRP are thermally distinguished by detecting contact point temperature, implying thermal visualization is possible. The heat conduc-tion simulation shows the thermal image displays overall thermal conductance of the sample from the back side to the contact point which is decided by contact scale, thermo-physical properties and material structure.
Exact Solution of Heat Conduction in Composite Materials and Application to Inverse Problems
Authors: Aviles-Ramos C. , Haji-Sheikh A. , Beck J. V. 
Published: March 2022

Abstract
Calculation of temperature in high temperature materials is of current interest to engineers. Aerospace industry encounters cooling problems in aircraft skins during the flight of high-speed air vehicles and in high-Mach-number re-entry of spacecraft. Generally numerical techniques are used to deal with conduction in composite materials. This study uses the exact series solution to predict temperature distribution in a two-layer body: one orthotropic and one isotropic. Often the exact series solution contains an inherent singularity at the surface that makes the computation of heat flux difficult. This singularity is removed, introducing a differentiable auxiliary function that satisfies the nonhomogeneous boundary conditions. An inverse heat conduction technique is used to predict surface temperature and/or heat flux.
Experimental Investigation of Heat Transfer and Pressure Drop Through Deep Microchannels in a (110) Silicon Substrate
Authors: Harms Todd M. , Kazmierczak Michael , Gerner Frank M. , Hölke A. , Henderson H. T. , Pilchowski J. , Baker Karl 
Published: March 2022

Abstract
Experimental results have been obtained for single-phase forced convection in deep rectangular microchannels. The microchannels were fabricated in a 2 mm thick silicon substrate by means of chemical etching. The tested configuration has 251 μm wide channels and 119 μm thick channel walls. The channel depth is 1030 μm and the channels cover a total projected area of 2.5 cm by 2.5 cm. A thin-film heater is deposited on the back side of the silicon substrate, corresponding to the entire projected channel area. The silicon substrate measures 2.9 cm by 2.9 cm, with only a 2 mm wide edge surrounding the channel area. All tests were performed with deionized water as the working fluid, where the liquid flow rate ranged from 5.47 cc/s to 118 cc/s. A critical Reynolds number of 1500 was found for this configuration, contrary to that of larger channels. The theoretical analysis as well as previous data found in the literature agree reasonable well with the experimental findings. This channel configuration has been shown to reduce temperature non-uniformity in the substrate compared to previous studies by utilizing relatively high flow rates. In addition, the theoretical analysis shows that increasing the channel depth can significantly improve the flow and heat transfer performance.
Turbulent Heat Transfer in a Forced and Unforced Two Dimensional Air Jet Impinging on an Isoflux Surface
Authors: Singer Edmund A. , Ortega Alfonso 
Published: March 2022

Abstract
Mean heat transfer and flow characteristics of a two-dimensional air jet impinging on a uniform heat flux surface were investigated. Measurements were made in a steady unforced jet, and in a jet with externally introduced forcing. The jet issued from a 24:1 aspect ratio rectangular nozzle. The heat transfer characteristics are parameterized by jet Reynolds number based on the hydraulic diameter and on the nozzle-to-plate spacing. Flow conditions (mean, turbulent fluctuations and power spectra) exiting the jet were measured and used to interpret their influences on the stagnation point heat transfer. A comparison of an unforced impinging jet to a forced impinging jet showed enhancements in the heat transfer rate of up to 57% with forcing.
The Effects of Inlet Turbulence on the Development of Fluid Flow and Heat Transfer in a Helically Coiled Pipe
Authors: Lin C. X. , Ebadian M. A. 
Published: March 2022

Abstract
In this paper, the effects of inlet turbulence on the development of turbulent flow and heat transfer in the entrance region of a helically coiled pipe are investigated by means of a fully elliptic numerical study. The k-ε standard two-equation turbulence model is used to simulate the three-dimensional turbulent flow and heat transfer. The governing equations are solved by a Control-Volume Finite Element Method with an unstructured nonuniform grid system. Numerical results presented in this paper cover a Prandtl number range of 0.02–100, and an inlet turbulence intensity range of 2–40 percent. The development of velocity field, temperature field, bulk turbulent kinetic energy, average friction factor, and average Nusselt number are discussed. It is found that bulk turbulent kinetic energy far from the entrance is not affected by the inlet turbulence level. Significant effects of the inlet turbulence level on the development of the friction factor and Nusselt number occur within a short axial distance from the entrance only.
Development of a High Flux Conduction Calibration Apparatus
Authors: Grosshandler William L. , Blackburn David 
Published: March 2022

Abstract
A new conduction calibration apparatus has been designed to deliver heat fluxes up to a maximum of 100 kW/m2 with an established goal of ± 5 % precision. This system will provide a close to purely diffusive (as opposed to radiative) heat flux boundary condition and, when compared to the gauge’s response in the National Institute of Standards and Technology (NIST) radiative calibration facility, act as a check on the sensitivity of a heat flux gauge to the mode of heat transfer. A platinum-plated copper block heated electrically with 2 kW power is designed to produce uniform temperatures up to 750 K across its face. A cold plate will be maintained around 290 K through pool boiling using a liquid refrigerant and a remote condenser. A 1 mm wide helium filled gap between the hot plate and the sensing surface of a cooled heat flux gauge will provide the high conductive fluxes desired (while limiting radiation to a few per cent and avoiding the uncertainties associated with contact resistance). Detailed numerical modeling of the device is being used to identify limitations and evaluate alternatives in the design, and to analyze the level of uncertainty associated with the facility. A description of the apparatus and the results of preliminary modeling are reported.
Laminar Forced Convection Near an Asymmetric Contraction in a Channel
Authors: McAuliffe Wayne E. , Wirtz R. A. 
Published: March 2022

Abstract
The flow and heat transfer characteristics in the region of an asymmetric contraction in a two-dimensional channel are studied numerically. The contraction is in the form of a step on one of the channel walls. Channel wall-to-wall spacing ranges from 2 step heights to 10 step heights, with Reynolds numbers, based on channel hydraulic diameter, ranging from 500 to 2500.
Separation and recirculation regions occur upstream from the contraction; the flow generally separates on the order of one step height upstream from the step and re-attaches approximately one-half the distance up the step face. In some cases there is a recirculation region on the top of the step, beginning just downstream from the leading edge of the step, and typically a few step heights in extent. Heat transfer is reduced in the recirculation regions, relative to that of a parallel-wall flow. In addition, there is heat transfer augmentation on the wall opposite the step, not only because of the contraction itself, but also enhanced by the flow around the recirculation regions. Correlations are reported for friction factor and for heat transfer augmentation and reduction, and results are reported for location of separation and reattachment points and for heat transfer across the entire region.
Thermal Transport Phenomena in Turbulent Gas Flows Through a Tube With High Constant Wall Temperature
Authors: Torii Shuichi , Yang Wen-Jei 
Published: March 2022

Abstract
A numerical study is performed to investigate thermal transport phenomena in turbulent gas flow through a tube with high uniform wall temperature. A k-ε turbulence model is employed to determine the turbulent viscosity and the turbulent kinetic energy. The turbulent heat flux is expressed by Boussinesq approximation in which the eddy diffusivity of heat is determined by a t2¯-εt heat-transfer model. The governing boundary-layer equations are discretized by means of a control volume finite-difference technique and numerically solved using a marching procedure. It is disclosed from the study that: (i) Like in a pipe with high uniform wall heat flux, laminarization takes place in a turbulent gas flow through a pipe with high uniform wall temperature, (ii) Once laminarization occurs, both velocity and temperature gradients at the wall diminish along the flow, resulting in a substantial reduction in both the turbulent kinetic energy and temperature variance across the whole tube cross section, and (iii) these attenuations cause a deterioration in heat transfer performance.
Acoustic-Wave Liquid Mixer
Authors: Zhu Xu , Kim Eun Sok 
Published: March 2022

Abstract
This paper presents a novel approach for microfluid mixing by loosely-focused acoustic waves (generated by piezoelectric Zinc Oxide thin film). Initial results show that our acoustic-wave liquid mixer (AWLM) produces a convection flow in liquid very efficiently, when it is driven by a sinusoidal wave with frequencies corresponding to the thickness-mode resonances (e.g. 240 and 480 MHz) of the piezoelectric film. The AWLM operates without any significant temperature increase in liquid, and will be very attractive for mixing temperature-sensitive fluids.
Microactuators Based on Electrothermal Expansion of Clamped-Clamped Beams
Authors: Chiao Mu , Lin Liwei 
Published: March 2022

Abstract
Thermally driven microactuators based on clamped-clamped beams have been successfully demonstrated. A theoretical model which includes both electrothermal and thermo-elastic responses of the micro beams has been established. These micro beams are made of heavily phosphorus doped polysilicon by a surface micromachining process. Theoretically, a 2 μm wide, 2.2 μm thick and 100 μm long beam can have a actuated displacement at the center point of about 2.7 μm under a 6 mA input current. The analytical results are consistent with experimental measurements which use computer image processing schemes to measure the lateral displacements.
Strength and Fracture of Micromachined Silicon Structures
Authors: Suwito Wan , Dunn Martin L. , Cunningham Shawn J. 
Published: March 2022

Abstract
We present our recent efforts to understand and characterize the mechanical behavior of micromachined single crystal silicon structures. This includes efforts directed toward the design and fabrication of free-standing thin film test structures and toward micromechanical tensile testing. We observed that in many cases, fracture of the test structures initiates at sharp corners that arise from the anisotropic wet etching process. Existing approaches do not appear to be suitable to correlate fracture initiation from these sharp corners. To remedy this, we propose a new approach that is able to describe the apparent strength scaling with specimen size that is observed experimentally. This scaling has obvious ramifications with regard to the design of reliable structures for microelectromechanical systems, without exhaustive verification testing.
Tr-1A Rocket Experiment on Nucleate Pool Boiling Heat Transfer Under Microgravity
Authors: Ohta H. , Kawaji M. , Azuma H. , Kawasaki K. , Tamaoki H. , Ohta K. , Takada T. , Okada S. , Yoda S. , Nakamura T. 
Published: March 2022

Abstract
To clarify the reason of inconsistent trends in the existing heat transfer data in microgravity nucleate boiling, the method to acquire the local heat transfer data and to observe in detail the bubble behavior from underneath was developed and introduced in the experiment by the use of the NASDA TR-1A ballistic rocket. The pool boiling experiment was conducted using ethanol as test liquid at an almost constant temperature of 25 to 30°C. The system pressure was varied from 0.01 to 0.48MPa with corresponding liquid subcooling from 3 to 95K. The steady state heat transfer is realized in microgravity at the conditions of moderate and high subcooling where the bubble size is determined so that the rate of evaporation of microlayer balances that of condensation at the bubble surface. On the other hand, the transition to burnout is unavoidable even at low heat flux when the liquid of low subcooling is concerned. The nucleate boiling heat transfer is dominated by the isolated or primary bubbles just generated on the heat transfer surface even in the high heat flux or the low liquid subcooling region where these bubbles lift the large coalesced one covering the entire heating surface. Two opposite trends of the heat transfer enhancement and deterioration are possible depending on the behavior of dry patches extending in the microlayer underneath the bubbles contacting directly with the surface.
Double Diffusive Convection in a Stratified Fluid Layer Induced by Thermal and Solutal Capillary Motion
Authors: Chan C. L. , Chen C. F. 
Published: March 2022

Abstract
Salt-finger convection in a double-diffusive system is a motion caused by the release of gravitational potential due to differential diffusion rates. The normal expectation is that, when gravitational field is reduced, salt-finger convection together with other convective motions driven by buoyancy forces will be rapidly suppressed. However, because the destabilizing effect of the concentration gradient is amplified by the Lewis number, with values varying from 102 for aqueous salt solutions to 104 for liquid metals, salt-finger convection may be generated at much reduced gravity levels. In the microgravity environment, the surface tension gradient assumes a dominant role in causing fluid motion. In this paper, we report experimental and numerical results showing the generation of salt-finger convection due to capillary motion on the surface of a stratified fluid layer.
A Second Law in Engineering Education
Authors: El-Sayed Yehia M. , Gaggioli Richard , Ringhausen David P. , Smith Joseph L. , Gyftopoulos Elias , Sama Dominick , Fiszdon Jerzy K. 
Published: March 2022

Abstract
Several panel sessions sponsored by the System Analysis Technical Committee of the ASME Advanced Energy Systems Division were held as a part of 1996 IMECE’s Symposium on Thermodynamics and the Design, Analysis, and Improvement of Energy Systems in Atlanta, GA. Panel Session on the Second Law in Engineering Education was one of them. Panelists included representatives of both, academia and industry. Discussion included the need to educate undergraduate engineers in the Second Law of Thermodynamics and to what depth this education should be. Educational approaches used by participants were also the subject of discussion.
An Investigation on Bubble Growth in Superheated Liquid During Rapid Decompression
Authors: Liu Chao , Zeng Danling 
Published: March 2022

Abstract
A mathematical model of bubble growth in superheated liquid during rapid decompression was built up on the basis of non-equilibrium thermodynamics. According to the principles of thermodynamics it is asserted that the bubble growth process can be described by a polytropic process rather than assuming that it goes along the saturation curve as usually suggested in existing article. The value of the polytropic exponent n is restrict to a ranges of 1 ≤ n ≤ nσ &lt; k to guarantee the existence of a positive driving force to drive the phase transition process. Numerical simulation of the bubble growth process was performed for water by using the model proposed. The results obtained were compared with experimental data provided by other authors. Good agreement was achieved.
Conversion of Ocean Thermal Energy With the “Salt Cycle”
Authors: Saikia Siddarth 
Published: March 2022

Abstract
A temperature gradient exists between the top and the depths of oceans, the “Salt Cycle” is targeted at converting this thermal energy. The phases of certain solutions (liquid-liquid or solid-liquid) separate out at lower temperatures enabling the separation of the solute. By placing the solute behind a semipermeable membrane, at a higher temperature, an osmotic pressure can developed. The pressure released into a turbine can generate power or may be put to other uses like desalination.
The Constructal Law of Structure Formation in Natural Systems With Internal Flows
Authors: Bejan Adrian 
Published: March 2022

Abstract
This paper outlines a series of recent developments that provide a theoretical basis for the formation of shape and structure in nonequilibrium (flow) systems subjected to overall constraints. It is shown that geometrical form can be deduced from a single principle: the geometric minimization of resistance to flow. This is illustrated in two ways: by minimizing the flow resistance between a finite volume and one point, and by minimizing the time of travel between a finite area and one point.
The discovery is that any volume element can have its shape optimized such that its flow resistance is minimal. This principle applies at any volume scale. The given volume is covered in successive steps of optimization and construction. Optimally shaped elements are grouped into a “construct,” and then the shape of the construct is optimized. The more visible portion of the optimized volume-to-point flow path that emerges is a tree network that is completely deterministic. This solution has a definite time direction: from small to large, hence the name “constructal.” Small size and slow and shapeless flow (diffusion) come first, and larger sizes and organized flows (streams) come later.
Evaluation of Zeotropic Refrigerant Mixtures R32/R134A in Flow Condensation
Authors: Shao D. W. , Granryd E. 
Published: March 2022

Abstract
Experiments on flow condensation have been conducted with pure R32, R134a and R32/R134a mixtures. The results have been represented in form of local and mean heat transfer coefficient, as well as pressure drop. The heat transfer data is compared with the prediction from correlations in literature. An analysis is also carried out on potential causes of heat transfer degradation associated with NARMs.
Discharge Gas Cooling in Vacuum Pumps
Authors: Prasad B. G. Shiva 
Published: March 2022

Abstract
Heating of the gas is an undesirable effect of the compression process, particularly in vacuum pumps and high pressure ratio reciprocating compressors. ‘Discharge gas cooling’ is analogous to the commonly known phenomenon of ‘suction gas heating’, but unlike the latter, discharge gas cooling is beneficial to the user of a vacuum pump. This paper describes a technique for modeling the complex heat transfer process by breaking it up in to different stages and calculating the heat transferred during each stage for estimating the discharge temperature. The method was validated by comparing the results with experimental data for a vacuum pump tested over a range of operating conditions.
Pressure Pulsation of Scroll Compressor
Authors: Itoh Takahide , Fujitani Makoto 
Published: March 2022

Abstract
Pressure pulsation in the scroll compressor was analyzed with three dimensional FLIC (flow in cell) method which was a kind of finite volume method.
In advance of analyses, the grid generation method for numerical analysis was established in the scroll compression chamber.
According to compression progress, grids in compression chambers are transformed and each conservation quantity which transport through the grid boundary was adjusted by moving boundary velocity.
The overset grid was used between compression chamber and discharge port.
In the overset grids, grids nodes of the discharge port are not located in same points of the compression chamber grid nodes. In this case the conservation quantity on the boundary is interpolated between every adjacent grids. However, we simplified interpolation with treating the discharge port as one grid.
Using this program, it is possible to predict the suction pressure pulsation, the compression pressure pulsation and the discharge pressure pulsation in the scroll.
Finally the supercharging construction using the suction pressure pulsation was developed and it is confirmed the supercharging effect of the suction path shape and the suction path length experimentally.
Finite Difference Time Domain Simulation of Scattering From Submerged Elastic Bodies
Authors: Nagem Raymond J. , Lei Xun , Felsen Leopold B. 
Published: March 2022

Abstract
A two-dimensional finite difference time domain (FDTD) algorithm is implemented to simulate wave propagation and scattering in a heterogeneous fluid-elastic environment. The FDTD algorithm is fourth-order accurate in space and second-order accurate in time. The perfectly matched layer (PML) absorbing boundary condition is adapted to eliminate artificial reflections caused by the boundaries of the finite computational domain. Computational accuracy is verified by considering radiation from a periodic array of pulsed line sources and from a fluid line source near a submerged elastic layer. The finite difference results are in excellent agreement with the numerically evaluated spectral integrals which can be derived for these problems. The finite difference algorithm is then applied to scattering from a rough fluid-solid interface, and to scattering from an elastic cylinder above or buried beneath a rough fluid-solid interface. Scattered signals are processed with the Gaussian windowed transform, which provides an initial image representation for signature identification and classification algorithms.