bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Enhanced Heat Transfer in Low Reynolds Number Flows in a Plate Heat Exchanger
Authors: Muley Arun , Manglik Raj M. 
Published: January 2022

Abstract
Steady-state heat transfer and pressure drop data for single-phase low Reynolds number flows (2 ≤ Re ≤ 400) in a plate heat exchanger (PHE) with chevron plates are presented. Three different chevron plate arrangements, with two symmetric (β = 30°/30° and 60°/60°) and one mixed (β = 30°/60°) plates, are considered in a single-pass, U-type, counter-flow PHE. The effects of the corrugation inclination angle β, and flow conditions on Nu and f characteristics of the PHE are investigated using vegetable oil as test fluid (130 &lt; Pr &lt; 290). The results indicate that as β increases, up to 3 times higher Nu are obtained in chevron plates compared to an equivalent flat-plate pack; the concomitant f, however, are up to 9 times higher. Correlations of the functional form
Nu(Re, Pr, β, de/L, μ/μw) and f(Re, β)
are developed, and they predict all available data within ±10%. Finally, the performance of chevron plates is evaluated relative to an equivalent flat-plate channel for two different operating constraints: (1) Fixed geometry and constant pumping power, and (2) fixed heat load and pressure drop.
Effect of Porous Fin in a Plate-Fin Heat Exchanger
Authors: Kim Seo Young , Kim Jin-Ho , Kang Byung Ha 
Published: January 2022

Abstract
The present experimental study investigates the impact of porous fin on the pressure drop and heat transfer in a state-of-the-art plate-porous fin heat exchanger. Systematic experiments have been carried out in a simplified model of plate-porous fin heat exchanger at the controlled test environment. The porous fins are made of aluminum-alloy foam materials with several permeabilities and a high porosity. The experimental results show that the porous fins can enhance the performance of plate-fin heat exchangers. The pressure drop and the heat transfer coefficients are significantly affected by the permeability of porous fin. The simple correlations of friction factor and Colburn j-factor are also given for future design purpose.
Molecular Tagging Velocimetry Applied to Buoyancy-Driven Convective Phenomena During Solidification
Authors: Wirtz K. , Koochesfahani M. , McGrath J. J. , Benard A. 
Published: January 2022

Abstract
Molecular Tagging Velocimetry (MTV) has been applied to quantify velocity fields associated with convective phenomena which occur during solidification in aqueous ammonium chloride solution (NH4Cl-H2O), a popular transparent low-temperature analog of metal alloys.
A phosphorescent line pattern was “written” into the melt to quantify one component of the velocity field within a plume and in the fluid surrounding the plume. These results represent the first quantitative, continuous field measurements of velocity for such studies. The data compare well with the magnitude of the maximum plume velocities estimated in the literature using particle tracking methods. Asymmetric and symmetric plume velocity profiles were quantified. Velocity fields associated with downward flowing sheaths of fluid surrounding the plume were quantified. Although the shape of the velocity profile measured using MTV compares reasonably well with that predicted by an analytical model proposed in the literature, significant differences were detected. The extension of the MTV method using a tagged plane, rather than a tagged line of phosphorescent fluid, for qualitative 3-D dynamic, visualization is described. This realization of the MTV method has the potential for revealing the basic three-dimensional structure of the velocity field.
The results presented here demonstrate that it is feasible to apply MTV as an advanced diagnostic measurement method to further improve our knowledge of convective phenomena which occur during solidification.
Dynamical Behavior of Slug Initiation Generated by Short Waves in Two-Phase Air-Water Stratified Flow
Authors: Ansari Mohammad R. 
Published: January 2022

Abstract
Two-phase air-water stratified flow was studied in a horizontal duct. The two-phase air-water flow was considered under atmospheric conditions. The non-linear field equations for air and water were coupled and solved using a finite difference method For this purpose, the two-phase flow analyzer ‘MINCS’ which was initially developed by Japan Atomic Energy Research Institute was used. The initial and boundary conditions were established in order to create a slug. The criterion for two-phase stratified flow instability was compared with the instability criteria based on linear analysis and the empirical correlations of other researchers. It was found that the gas velocity required for initiation of slugging is much lower than defined by the Kelvin-Helmholtz instability criteria. But the instability criteria for the on set of slugging agreed well with Mishima and Ishii prediction. The reason for the necessary lower air velocity in comparison with Kelvin-Helmholtz relation is the growth of short waves which create slugs which is discussed here. The dynamical behavior of slug initiation which was generated by short waves was presented. The results showed that as void fraction was decreased, slug generated with lower air velocities in a shorter duct length and in a shorter period of time with a bigger wetted area. Also, the higher air velocities create slug with higher growth rate in a shorter duct length.
Study of Heat Flux Gages Using Sensitivity Analysis
Authors: Dowding Kevin J. , Blackwell Ben F. , Cochran Robert J. 
Published: January 2022

Abstract
The response and operation of a heat flux gage is studied using sensitivity analysis. Sensitivity analysis is the process by which one determines the sensitivity of a model output to changes in the model parameters. This process uses sensitivity coefficients, which are defined as partial derivatives of field variables (e.g. temperature) with respect to model parameters (e.g. thermal properties and boundary conditions). Computing sensitivity coefficients, in addition to the response of a heat flux gage, aids in identifying model parameters that significantly impact the temperature response. A control volume finite element based code is used to implement numerical sensitivity coefficient calculations, allowing general problems to be studied. Sensitivity coefficients are discussed for the well known Gardon gage.
Validation of Methodologies for the Estimation of Blood Perfusion Using a Minimally Invasive Probe
Authors: Robinson Paul S. , Scott Elaine P. , Diller Thomas E. 
Published: January 2022

Abstract
Parameter estimation techniques have been utilized in the development of methodologies to noninvasively measure blood perfusion using a new thermal surface probe. The core of this probe is comprised of a small, lightweight heat flux sensor that is placed in contact with tissue and provides time-resolved signals of heat flux and surface temperature while the probe is cooled by air jets. Parameter estimation techniques were developed that incorporate heat flux and temperature data with calculated data from a biothermal model of the tissue and probe. The technique simultaneously estimates blood perfusion and thermal contact resistance between the probe and tissue. Validation of this concept was carried out by experimentation with controlled perfusion through non-biological porous media. A controlled rate of uniform flow of warm water through a fine pore sponge provided a phantom model for blood perfusion through biological tissue. The parameter estimation technique was applied to measurements taken over a range of flow rates. Heat flux and temperature measurements and the resulting perfusion estimates correlated well with the experimentally imposed perfusion rate. This research helps establish the validity of using this method to develop a practical, noninvasive probe to clinically measure blood perfusion.
Optimization of Enhanced Steam-Ejector Applied to Steam Jet Refrigeration
Authors: Kouremenos D. A. , Rogdakis E. D. , Alexis G. K. 
Published: January 2022

Abstract
Ejectors are used for a wide range of applications. Refrigeration systems have, a long established history. Ejector refrigerators working on steam or halocarbon refrigerants provide a high level of flexibility. Ejector can also be used in solar-powered refrigeration systems and absorption-refrigeration systems.
There are very few comprehensive theoretical studies even though several models for ejectors in literature. A new ejector theory was developed by Munday and Bagster (1977). This theory depends on the assumption of two discrete streams, the motive stream and the secondary stream. The two streams maintain their identity down the converging duct of the diffuser. At some section the secondary flow reaches sonic velocity. The shocking and mixing occur at the very end of the converging cone resulting in a transient supersonic mixed stream. There is no supersonic deceleration and a shock takes place immediately on mixing. The mixed stream will shock to the subsonic, found by the intersection of the Fanno and Rayleigh lines. After that the stream is brought to near zero velocity in the diffuser.
In the present work this theory is used as a basis, in order to develop a computerized model of ejector with particular reference to steam-ejector at various operating conditions. The results are compared with available from the literature experimental data. Also a parametric study is conducted in order to reveal the influence of the various parameters on the performance of the steam jet refrigeration.
Intelligent Computer Aided Design, Analysis and Improvement of Combined Cycle
Authors: Wu C. 
Published: January 2022

Abstract
This paper describes the use of an ICAI (Intelligent Computer Aided Instruction) software package for the design, analysis and improvement of the combined cycle. The traditional cycle design and analysis is long and tedious. Obtaining an accurate combined cycle performance quickly is necessary in the design process. Objectives for improvements which cannot be easily accomplished using the conventional method are emphasized. As an example of the capabilities of the package, the design, analysis and improvement of an innovative Brayton/Ericsson cycle are given.
Impact of Gas Turbine De-Rating on the Performance and on the Economics of Big-GT Cycles
Authors: Walter Arnaldo , Llagostera Jorge , Gallo Waldyr L. R. 
Published: January 2022

Abstract
Biomass gasification and the sequential use of the produced gas in gas turbines (the so called Biomass Integrated Gasifier - Gas Turbine cycles) is one of the technologies that can minimize carbon dioxide emissions during electricity generation.
As the primer mover of such power plants, gas turbine performance is a key parameter on the economics of BIG-GT systems. At least within the first generation of this technology, gas turbines originally designed for burning conventional fuels (natural gas and light oils) will be adapted to syngas burning. At this stage some changes on combustion chamber will be required, and some modifications on operational control parameters must be done as well. Gas turbine de-rating (reduction of gas turbine firing temperature) is the simplest control alternative to avoid problems concerned with reduction of compressor surge margin and increased thermal loads. However, from the performance view point of the gas turbine (and also for the whole system), this seems to be the worst option.
In this paper the de-rating alternative is analyzed both from a thermodynamic and an economic point of view. A BIG-CC system based on a nearly atmospheric air-blown gasifier is considered. De-rating is analyzed vis-à-vis moderate increases of compressor pressure ratio. A simulation code (developed by the authors) able to perform analysis of thermal power systems (and particularly BIG-GT systems) is applied on this study. Cost functions are used to estimate the total installed unit capital cost, allowing a proper evaluation of electricity generating costs. The results indicate that electricity costs are sensitive to de-rating either due to the reduction on electricity generating efficiency and to the increase on the unit capital cost.
A Survey on GHP Technology
Authors: Dentice d’Accadia Massimo , Sasso Maurizio , Sibilio Sergio 
Published: January 2022

Abstract
The Gas engine driven Heat Pump (GHP) basically consists of a reversible vapour compression heat pump with an open compressor, driven by an internal combustion gas fueled engine instead of an electric engine.
The possibility of recovering waste engine heat via a jacket and an exhaust heat exchanger, together with the use of an alternative engine closely follows the heating building load varying the engine speed continuously, can be regarded as the most important peculiarities of this equipment: these features allow higher performances and lower running costs than Electric Heat Pump (EHP).
In this paper the results of the study and research performed by the DETEC Department of the FEDERICO II University of Naples are reported; the main goal of the research was the assessment of the on-site small GHP performance but, a wider analysis on GHP was performed, covering some related topics: the historical development and market situation, the reasons for GHP use, and finally, the metrological and performances analysis.
Evaluation of the Acoustic Properties of Silica Aerogels
Authors: Conroy John F. T. , Hosticka Bouvard , Davis Scott C. , Norris Pamela M. 
Published: January 2022

Abstract
The acoustic transmission velocity in silica aerogel was measured as a function of the gas type and pressure in the aerogel pores. This was done with air-coupled ultrasonic transducers configured for differential pulse transit time measurements. At high pressures, the fractional reduction of acoustic velocity as a function of mean free path is identical in different gasses. This may indicate a thermal relaxation phenomenon, with the relaxation time dependent upon the rate of collision between gas molecules and the silica pore walls.
Some Experiments on the Fracture Behavior of Microcellular Polycarbonate
Authors: Barlow Chris C. , Bordia Rajendra K. , Flinn Brian , Weller John E. , Kumar Vipin 
Published: January 2022

Abstract
The fracture behavior of microcellular polycarbonate (PC) was investigated. A work of fracture test was conducted on double-edge-notched-tension (DENT) specimens and this produced reliable tensile failure data the work of fracture was found to decrease linearly with foam relative density. A critical initiation stress intensity factor Kc was calculated from fracture toughness tests in which compact tension specimens were pulled in tension. In all tests, the impact/fracture behavior of these foams was a strong function of foam density.
In-Line Measurement of Gas Solubility in Polystyrene and Polyethylene Terephthalate Melts During Foam Extrusion
Authors: Zhang Qiang , Xanthos Marino , Dey Subir K. 
Published: January 2022

Abstract
In this paper, a new in-line method was used to directly measure the gas solubility in polymer melts during foam extrusion. Metered quantities of polymer and specific gases were blended in a single screw extruder which is capable of producing polymeric foams of variable density. A specially designed optical window and flow restrictor valve placed between the die and the end of the extruder were used to generate dynamic solubility data by observing the onset of bubble formation/dissolution at the window through a microscope-CCD camera-monitor/recorder system. Solubility data were determined for systems involving nitrogen, argon and carbon dioxide in polystyrene and polyethylene terephthalate at different temperatures. Good agreement with literature data on the PS-CO2 system was obtained.
Large Displacement Piezoelectric Actuator Configurations
Authors: Dancila D. Stefan , Armanios Erian A. 
Published: January 2022

Abstract
In the present work three configurations of compact size, large rotation piezoelectric bimorph actuators are proposed and analyzed, and their static response to control voltage is analytically modeled. The actuator configurations can be characterized as thin, coiled, single curvature bimorph piezoelectric shells with thickness polarization and electroded faces. Compared to a cantilevered bimorph, the configurations analyzed in this work are more compact and allow an increase in actuator displacement output — in this case a rotation — without degradation of blocked moment output. The analytical models developed are verified by comparison with finite element results for a set of generic geometric parameters defining each of the three configurations. Relevant electroelastic properties of a typical piezoelectric material are assumed. An excellent correlation of results is found, confirming the accuracy of the analytical modeling of response as well as the large rotation capability of this class of actuators.
Automotive Composites Consortium Generic Tube Crush Program: Resin Transfer Molded Tubes
Authors: Browne Alan L. , Houston Dan Q. , Watling Patrick J. , Lalik Larry 
Published: January 2022

Abstract
This paper provides a brief summary of the major findings of the RTM (Resin Transfer Molding) portion of a generic tube crush study conducted by the Energy Management Working Group (EMWG) of the Automotive Composites Consortium (ACC). A total of 147 crush tests were performed on 55 × 55 mm square hollow tubes using plug-type crush initiators. The principal fiber was E-glass and the resin used was Dow Derakane 411-C50 vinylester. Parameters considered were tube fiber architecture and wall thickness, test crush rate — static vs. dynamic —, and test temperature/humidity. Principle findings were that fiber architecture, tube wall thickness, and whether the test was a static or dynamic crush test all can produce significant differences in tube crush force and specific energy absorption (SEA); also that both tube quality and postcuring are strongly linked to the quality and generality of the information gathered/conclusions that can be drawn.
Development of a Composite Front Structure for Automotive Crashworthiness
Authors: Botkin Mark , Browne Alan , Johnson Nancy , Fidan Sukru , Jeryan Richard , Mahmood Hikmat , Wang Richard , Lalik Larry , Peterson Doug 
Published: January 2022

Abstract
This paper will summarize the results of a major project of the Automotive Composites Consortium (ACC) to focus on the use of composites in a vehicle front-end structure. The emphasis of the project was to replace the entire steel front structure of a production automobile with a molded composite front structure. The project focused on the development of a completely new reinforcement architecture which emphasized production feasible preforming methods: triaxially braided glass fibers over foam cores make up the upper and lower rails and the connecting panel can be formed from either thermoformed continuous strand mat or directed fiber, and utilized an Resin Transfer Molding (RTM) process. The front structure of the vehicle was redesigned and replaced with production-feasible composite components designed for crash energy management requirements as well as other overall structural considerations. The paper will describe the many design, analysis and test phases of the project which led up to a successful barrier test to verify structural crashworthiness. A fully dressed and instrumented vehicle was built up to incorporate the composite front structure and the vehicle was barrier crash tested at 56 kph. The vehicle passed the test — all performance measures were well within the Federal MVSS requirements — and all but one measure yielded improved performance over the all-steel production vehicle. In addition, the composite parts are 25% lighter than the steel parts they replace.
An Exit Burr Model for Drilling of Metals
Authors: Saunders L. Ken Lauderbaugh , Mauch Craig A. 
Published: January 2022

Abstract
The mechanics of the formation of exit burrs for drilling metals are analyzed. A burr formation model is developed where the material in front of the drill is modeled as a circular plate of varying thickness. The drilling thrust force is distributed as a pressure along the plate. Material removal continues until a failure condition is reached. At the point of failure of the plate the remaining material is bent out to form the burr. The model also includes temperature effects. Experimental verification was conducted on 2024-T351 aluminum and on 7075-T561 aluminum. Two types of drill geometry were considered. The model accurately predicts the trends in the data However, the burr formation model over predicts the magnitude of the burr due to the failure criteria chosen and the limitations of elastic plate models.
Global Coordinate Method for Determining Sensitivity in Assembly Tolerance Analysis
Authors: Gao Jinsong , Chase Kenneth W. , Magleby Spencer P. 
Published: January 2022

Abstract
Tolerance sensitivity indicates the influence of individual component tolerances in an assembly on the variation of a critical assembly feature or dimension. Important applications include assembly tolerance analysis and tolerance allocation. This paper presents a new method for determining tolerance sensitivity using vector loop assembly tolerance models. With a vector loop model, the assembly kinematic constraints or assembly functions can be established automatically as implicit functions. This method evaluates the derivatives of the kinematic constraint equations with respect to both manufactured dimensions and assembly variables. The derivative matrices are then used to calculate the tolerance sensitivity matrix. This is a closed form method which relates the derivatives of the assembly functions to the coordinates of the joints or nodes and the orientations of the vectors and the local joint axes in an assembly. It is accurate, simple and very suitable for design iterations.
Reducing the Need for Cutting Fluids in Drilling by Means of Modulation Assisted Drilling
Authors: Ackroyd B. , Compton W. D. , Chandrasekar S. 
Published: January 2022

Abstract
The superposition of controlled modulation during drilling is known to result in consistent chip breakage under a wide variety of operating conditions in materials such as aluminum and steel. Modulation is shown to be equally effective to cutting fluids in reducing mean force levels and may provide reduced mean force levels even under operating conditions where cutting fluids are ineffective. The replacement of cutting fluid with modulation has no significant deteriorating effect on surface finish. These observations suggest that the use of superimposed low-frequency modulation could reduce the need for cutting fluids in drilling.
Isophote Based Machining for Feature Intensive Surfaces
Authors: Han Zhonglin , Yang Daniel C. H. 
Published: January 2022

Abstract
This paper presents a novel approach for generating efficient tool paths in machining free-form surfaces. Concept of iso-phote is used to facilitate tool-path generation. An iso-phote is defined as a region on a surface where the normal vector does not differ by more than a prescribed angle from a fixed reference vector. The boundary curves of the iso-phote, called iso-inclination curves, are numerically generated and are served as the initial master tool paths. These iso-inclination curves are then projected to a 2D plane which is perpendicular to the fixed reference vector. 2D curve offsetting of the projected iso-inclination curve is then performed. The resulted 2D offset curves are projected back to 3D surface to form final tool paths. The resulted tool paths can guarantee the satisfaction of machining tolerance requirements. A comparison study of this iso-phote based machining with the conventional iso-parametric machining and the iso-planar machining shows favorite result for the new approach.