bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric Analysis and Multi-Objective Optimization for Energy-Efficient and High-Performance HVAC Air Filter Design and Selection
Authors: Al-Azba Mohammed , Mahgoub Mohamed 
Published: July 2023

Abstract
Heating, ventilation, and air conditioning (HVAC) systems are notorious for their high energy consumption in buildings, particularly in regions with extreme cooling or heating demands. Air filters play a vital role in these systems, affecting both energy efficiency and indoor air quality. However, high-efficiency filters, due to their significant increase in airflow resistance, require excessive energy compared to low-efficiency filters. This poses a challenge in finding the optimal compromise between reducing energy consumption and enhancing indoor air quality. To address this challenge, a meticulous selection process is crucial in achieving a middle ground that satisfies both objectives. Proper sizing and design of air filters are therefore essential for successful HVAC projects. This paper introduces the utilization of optimization techniques as decision-support tools to determine the optimal design parameters of commonly used HVAC air filters under various scenarios. The developed model incorporates multiple objectives and design criteria, including life-cycle cost (LCC), filter size, and efficiency. By leveraging the differential evolution optimization technique, an algorithm is developed to forecast a range of optimal solutions (Pareto front) based on predefined system criteria and boundary conditions. The model is extensively tested and demonstrates exceptional performance in returning optimal solutions, in addition to the capability of narrowing down and converging to a single value. This methodology holds significant potential in assisting investment decisions concerning HVAC air filters, providing valuable insights for optimizing energy efficiency while ensuring satisfactory indoor air quality.
Implementation of Fracture and Flow Stress Models for AA5052-H32 Sheet Deformed Through Shock Tube–Based Forming Technique
Authors: Barik Saibal Kanchan , Ganesh Narayanan R. , Sahoo Niranjan 
Published: July 2023

Abstract
Selection of flow stress models and fracture models to model sheet deformation at high strain rates is of great concern. The same is attempted in the present work during shock tube impact forming of 1-mm-thick AA 5052-H32 sheet using a rigid nylon striker. Lab scale experiments and finite element simulations using DEFORM 3D are conducted for the purpose. Johnson–Cook flow stress model and Modified Johnson–Cook flow stress model along with fracture models like normalized Cockcroft and Latham model, Rice and Tracey model, Oyane model, and McClintock model are tested for their accuracy and consistency. The fracture strain and fracture pattern evaluation suggest that the modified Johnson–Cook flow stress model and Rice and Tracey fracture model are suitable for fracture prediction, and it is better to use these together for fracture evaluation. An alternate method of evaluating rate-dependent tensile properties of sheet at higher strain rates is proposed and delivered acceptable fracture prediction results. Finite element simulations using Hollomon power law predict a strain rate of 1925/s at a striker velocity of 49.79 m/s, which is in the range of values in literature for explosive forming. Systematic shock tube forming experiments for calibrating the fracture models are acceptable.
Semi-Analytical Model for 3D Multilayered Rolling Contact Problems With Different Creepage Combinations
Authors: Xi Yinhu , Li Bo , Almqvist Andreas 
Published: July 2023

Abstract
In this work, a semi-analytical model replicating 3D rolling contact problems with elastic coating layers has been proposed. The dimension reduced boundary element-based model rests on the conventional half-space assumptions, with influence coefficients describing the relationship between the stress and the displacement. In this model, the influence coefficient describes the stress–strain relationship for multilayered materials, which is derived from the corresponding frequency–response functions. The governing equations for 3D rolling contact problems are solved efficiently using the conjugate gradient method with the classical fast Fourier transformation (FFT)-based technique to accelerate the calculation of the integral equation relating the stresses to the strains, and all the possible creepages, i.e., the longitudinal, lateral, and spin creepages, are considered. The results obtained with the present numerical model are compared with existing results, and good agreement is found. Some selected results are presented to show the effect of the material elasticity and the thickness of the coating, and the layering, on the traction distribution and the traction coefficient under different creepage combinations. In this way, this work provides important information related to the composition of layered coatings in rolling contact applications.
A Practical Approach to Design for Quality
Authors: Abdou George H. , Basaly Nadia A. , Billatos Samir B. 
Published: July 2023

Abstract
To be successful in a competitive business environment, it is important to deliver products that meet customer’s requirements with respect to quality, cost, and delivery schedule. But to continue to be successful in a global competitive environment, it is important to improve product quality continuously. To improve product quality, product development cycle must be examined thoroughly and continuously and methods of shortening this cycle must be developed.
Experimental and Numerical Investigation of a Friction Oscillator
Authors: Hinrichs Nikolaus , Oestreich Markus , Popp Karl 
Published: July 2023

Abstract
Friction induced self-sustained oscillations, also known as stick-slip vibrations, occur in mechanical systems as well as in everyday life. Examples are stick-slip motions which lead to squealing railway wheels, grating brakes, rattling machine tools or the cozy sound of a violin. The robust limit cycles of stick-slip motions can be broken up by an additional harmonic external excitation. The extended nonsmooth system of a friction oscillator including a nonsmooth friction law and an additional external excitation shows rich bifurcational behaviour. On the basis of a one-dimensional map stability analysis and the determination of Lyapunov exponents has been carried out similar to the logistic map (Oestreich et al., 1996a).
The present paper focuses on the comparison of the dynamical behaviour of a simple mechanical model and the dynamics observed in experiments. Since in engineering systems the friction characteristic is often not known or is varying for different test parameters, first the friction characteristic is determined from experiments with different test conditions. In the next step the results of the simulations using the identified friction characteristics will be compared with measurements of the dynamics of the friction oscillator with pure external excitation, pure self-excitation and simultaneous self- and external excitation. An additional verification of the identified friction characteristic can be done by means of a comparison of phase curves, trajectories in the three dimensional state space and bifurcation diagrams.
Stability Analysis of Thermocapillary Convection in Rectangular Cavities
Authors: Xu Jieyong , Zebib Abdelfattah 
Published: July 2023

Abstract
This paper presents stability analysis on thermo-capillary convection of acetone (Pr = 4.4) in rectangular cavities using direct numerical simulation. Influence of the Reynolds number (Re) and cavity aspect ratio (Ar) on motion is investigated. Results are exhibited for streamline and isotherm patterns at different values of Re and Ar. Neutral stability curves for transition to time-dependent convection are delineated for this Pr = 4.4 fluid in the Re - Ar plane, and compared with our results for fluids with Pr = 10.0, 6.78 and 1.0. Several interesting features of these diagrams are discussed. One important conclusion we have from the comparison is that Arcr increases as Pr decreases. Thus, it appears that large values of both Ar and Re are necessary to induce thermocapillary oscillations for small Pr fluids such as liquid metals. On the other hand, energy analysis is performed for the oscillatory flow in the neighborhood of critical points in order to gain insight of mechanisms leading to instability. Results are provided for flows near both critical points with Ar = 3.0.
Thermocapillary Driven Turbulent Heat Transfer
Authors: Arpacı Vedat S. , Kao Shu-Hsin 
Published: July 2023

Abstract
A thermal Kolmogorov scale for thermocapillary driven turbulent flows, ηθ∼(1+1Pr)1/4(να2Ps)1/4, Pr≥1 or,ηθ∼(1+Pr)1/4(α3Ps)1/4, Pr≤1ν, α respectively being kinematic and thermal diffusivities, Pr the Prandtl number and Ps the production rate of thermocapillary energy, is proposed.
A model for thermocapillary-driven turbulent heat transfer,Nu∼ΠS1/3, is developed in terms of these scales. HereΠs∼Ma1+Pr-1=MaPr1+Pr,Ma = ℓΔσ/μα (Marangoni number), ℓ, Δσ and μ respectively being a characteristic length, surface tension difference and dynamic viscosity.
Transient Radiative Transfer Through Scattering Absorbing Media
Authors: Mitra Kunal , Kumar Sunil 
Published: July 2023

Abstract
This paper outlines the formulation of the different methods for determining transient radiative transfer through scattering absorbing media. A boundary driven radiative problem is considered in a one-dimensional plane-parallel slab. The different methods of solving the transient radiative transfer equation include the P1, P3, and P5 approximations, two-flux method, and eight, twelve and sixteen discrete ordinates methods. In addition, the general transient radiative transfer equation is also solved by direct numerical integration without any simplifying assumptions. Different orders of approximation for the phase function are considered as is a parametric analysis of the different parameters such as the scattering albedo and optical depth is performed. The propagation speed obtained and the magnitude of the transmitted and back-scattered fluxes for different models obtained are a function of the approximation used to represent the intensity distribution.
Feasibility of Far-Infrared Radiation Modulators Using High-TC Superconductors
Authors: Zhang Z. M. 
Published: July 2023

Abstract
The potential of using high-Tc superconductors as intensity modulators for far-infrared radiation is investigated in this work. Reflectance and transmittance for several design structures are computed using the published optical constants of the superconductor YBa2Cu3O7 and substrate materials. Notable differences in the reflectance and transmittance between the superconducting state and the normal state are illustrated. The best results are obtained based on the reflectance of thin films (10 nm – 50 nm thick) on thin substrates (less than 100 μm thick) and for radiation incident on the substrate. This study demonstrates that high-Tc superconductive thin films can be used to build far-infrared radiation modulators. Future experimental study is recommended in order to materialize this promising thermo-optical device.
Turbulent Heat Transfer in Rotating Flows
Authors: Arpaci Vedat S. , Kao Shu-Hsin 
Published: July 2023

Abstract
A Kolmogorov scale for rotative turbulent flowsη∼(ν3T)1/4,T being the production rate of centrifugal energy, is introduced. A torque-coefficient for turbulent flow between rotating cylinders leads, in terms of this scale, to CT∼Ta1/3,Ta = Ω2R1d3/ν2, d, R1 and Ω, respectively being Taylor number, the gap between cylinders, inner cylinder radius and angular velocity.
Two thermal Kolmogorov scales for rotating turbulent flows,ηθ∼(α3Tθ)1/4, Pr≪1ηθ∼(να2Tθ)1/4, Pr≫1Tθ, ν and α respectively being the thermal production rate of centrifugal energy, the kinematic and thermal diffusivities, are proposed.
Two heat transfer models for turbulent flow between rotating cylinders, in terms of these scales, are shown to beNu∼(TaPr2)1/3, Pr≪1Nu∼(TaPr)1/3, Pr≫1.
A Review of Correlations for Turbulent Flow Characteristics in Enhanced Tubes
Authors: Ravigururajan T. S. 
Published: July 2023

Abstract
The pressure drop and heat transfer correlations needed for the performance prediction of the enhanced tubes can be developed using either an analogy approach or an empirical technique. These two methods are explained along with the many correlations which have been developed based on them. The numerous studies pose a dilemma for the designer on selecting the most appropriate correlation. The paper outlines the various correlations that are available for predicting the thermal performance of turbulent flows in enhanced tubes. Specific correlations that are valid for particular enhancement types as well as general correlations are presented. The correlations were applied to a comprehensive data base and the predictions were analyzed. A parametric analysis that was carried out using the different correlations indicate interesting features caused by the influence of enhancement design parameters. In particular, the design variables affected the heat transfer/friction factor characteristics differently for various tube types.
Jet Impingement Boiling From Circular Free-Surface Jets During Quenching Experiments
Authors: Hall David E. , Incropera Frank P. , Viskanta Raymond 
Published: July 2023

Abstract
This paper reports results from an experimental study of boiling heat transfer during quenching of a cylindrical copper test piece by a subcooled, circular, free-surface water jet. The disk was heated to approximately 650 °C, and as quenching occurred, transient temperature measurements were taken at discrete locations near the surface and applied as boundary conditions in a conduction model to deduce transient heat flux distributions at the surface. Results are presented in the form of heat flux distributions and boiling curves for radial locations varying from the stagnation point to ten nozzle diameters for jet velocities between 2.0 and 4.0 m/s (11,300 ≤ Red ≤ 22,600). Data for nucleate boiling in the stagnation region and spatial distributions of maximum heat flux are presented and are in good agreement with correlations developed from steady-state experiments. Spatial distributions of minimum film boiling temperatures and minimum film boiling heat fluxes are also reported and reveal a fundamental dependence on jet splashing and streamwise location.
An Experimental Study of Heat Transfer in an Internally Finned Tube
Authors: Huq Mafizul , Huq A. M. Aziz-ul , Rahman Muhammad M. 
Published: July 2023

Abstract
This paper reports new experimental data for turbulent fluid flow and heat transfer in a tube having internal fins. An experimental set-up was designed to study the heat transfer performance in the entrance region as well as in the fully-developed region. The tube and the fin assembly was cast from aluminum to avoid any thermal contact resistance. The length of the test section was 15.2 m. The inner diameter of the tube was 70 mm. The tube contained six equally spaced fins of height 15 mm. Air was used as the working fluid in all experiments. The Reynolds number based on hydraulic diameter ranged from 2.6 × 104 to 7.9 × 104. Heat was supplied from an electrical heating system providing an uniform heat flux around the tube periphery over the entire length of the test section. Results exhibited high pressure gradients and high heat transfer coefficients in the entrance region, approaching the fully developed values away from the entrance section. Nusselt numbers of the finned tube were compared with those for an unfinned (smooth) tube for both constant Reynolds number and constant pumping power. The enhancement of heat transfer rate due to integral fins was found to be very significant over the entire range of flow rates studied in this experiment. Heat transfer coefficient, based on inside diameter and nominal area of finned tube exceeded unfinned tube values by as much as 112%. When compared at constant pumping power, an improvement as high as 52% was observed for the overall heat transfer rate. The results of this study indicates that significant enhancement of heat transfer is possible by using internal fins without sacrificing any additional pumping power. The experimental results are expected to be very useful for the design of pipelines and heat exchanger tubes.
Numerical Simulation of Free Convection Heat Transfer From Localized Discrete Heat Sources in a Vertical Channel
Authors: Campo Antonio , Manca Oronzio , Morrone Biagio 
Published: July 2023

Abstract
This paper addresses the problem of natural convection cooled channels heated with flush-mounted discrete heat sources: this configuration is more realistic for the modelization of the cooling of electronic devices. The two-dimensional, laminar and steady-state problem is investigated numerically by the full elliptic Navier-Stokes and energy equations in a composite domain. The computational domain is I-shaped and is made by the channel and two rectangular reservoirs. The thermal behavior of a channel symmetrically heated by a single flush-mounted strip as function of the strip position with respect to the inlet section is investigated. Wall temperature profiles as well as the velocity and local Nusselt numbers as functions of the nondimensional coordinates are shown for channels heated by five strips per each wall. The analysis is carried out in the aspect ratio, height of plates/channel gap, and the Rayleigh numbers in the ranges 1–10 and 103–105, respectively. The wall temperature profiles show useful indications on the correct position of the heated strips with respect to the channel inlet in order to attain higher heat transfer rate coefficients. The velocity profiles at the inlet and exit sections are strongly influenced by the Rayleigh numbers. The local Nusselt values show that, for different values of the aspect ratio, the channels behave as uniformly heated walls at lower Rayleigh numbers. A correlation for the average Nusselt number in terms of Rayleigh channel number is given.
Prandtl Number Effect on Natural Convection Resonance
Authors: Antohe B. V. , Lage J. L. 
Published: July 2023

Abstract
We report on recent findings of natural convection resonance under time periodic horizontal heating. The transport phenomena is investigated numerically considering a rectangular enclosure filled with fluid or with fluid saturated porous medium. Numerical simulations, of various configurations, indicate that the natural convection activity within the enclosure peaks at several discrete frequencies, with the climax attained at a heating frequency referred to as the resonance frequency. A general estimate of the resonance frequency is obtained theoretically via a system of non linear equations, function of the average Rayleigh number, the Prandtl number, the enclosure aspect ratio, the heating amplitude, and the Darcy number for the porous medium case. Theoretical predictions considering various Prandtl numbers agree well with the numerical results. A simplified theoretical model antecipates the resonance frequency varying with Pr1/2 for the porous medium enclosure, a result confirmed by the numerical data. The convection intensity within the enclosure is shown to decreases with either increasing or decreasing Pr from its optimum value around 1. This behavior is explained as a dual effect: at low Pr the high thermal diffusivity reduces buoyancy inside the enclosure; at high Pr the high momentum diffusivity (viscosity) damps the flow wheel inside the enclosure. Both effects justify the observed reduction in the natural convection activity inside the enclosure.
Experimental Study of the Effects of Thermal and Solutal Convections in the Continuous Cast of a Binary Mixture
Authors: DeZego Shawn E. , Jones W. Kinzy , Dong Z. F. , Ebadian M. A. 
Published: July 2023

Abstract
An experimental study of the solidification process for the continuous cast of a binary NH4CI-H2O solution with varying inlet temperature and composition has been performed. Thermal and solutal density gradients have been found to strongly affect flow in the liquid region and are mainly responsible for the redistribution of species on the macroscopic scale. Flow visualizations have shown that dense solute-rich solution, rejected from the mushy zone, was redistributed into the upper regions of the liquid melt during cases of hypoeutectic initial concentrations. Localized remelting and shearing of columnar dendritic growth for the hypoeutectic cases and the redistribution and melting of equiaxed dendritic growth for the hypereutectic cases have also been found to strongly depend on the solution inlet temperature. It was established that the extent of equiaxed free solid that accumulated in the lower region of the liquid melt for the hypereutectic cases was dependent on the initial solution composition. Concentration histories show that segregation of species along the vertical centerline in the liquid pool have been measured to be in excess of 4% for some cases during quasisteady conditions. The warm buoyant solution entering the liquid melt via the feeding nozzle significantly increased convective effects that were not detected in previous research on static test sumps.
Experimental Study of Coupled Thermal and Neutronic Instabilities of Two-Phase Flows in a Boiling Channel
Authors: Rao Y. F. , Fukuda K. , Hashii N. 
Published: July 2023

Abstract
An experimental simulator is proposed for studying the mechanism of the two-phase flow instabilities in a boiling channel that involves coupled thermohydraulic and thermoneutronic feedbacks. In the experimental simulator, the thermohydraulic feedback loop is dealt with by a conventional two-phase flow heat transfer loop in which the coolant of water is circulated, while the thermoneutronic or void-reactivity feedback loop is partially simulated with a computer using the point-reactor model for the neutron dynamics and the lumped parameter model for the fuel dynamics to model the interaction between the average void fraction and the heating rate to the boiling two-phase flow. Experiments are conducted with varied fuel-time constants and void-reactivity coefficients to investigate their effect on the coupled instability. The experimental simulator is shown to be capable of revealing the fundamental characteristics of the coupled thermal and neutronic instabilities as have been discussed by previous analytical studies.
Enhancement of Critical Heat Flux in Subcooled Flow Boiling of Water by Use of a Volatile Additive
Authors: Pabisz Ronald A. , Bergles Arthur E. 
Published: July 2023

Abstract
The present investigation considers the effect of a 1-pentanol additive in water on the critical heat flux (CHF) and pressure drop in forced subcooled boiling. A small quantity of 1-pentanol was added to distilled water with the objective of getting an approximate 2% by weight mixture, which had been found to give superior performance in previous studies of pool and flow boiling.
Experiments were performed using stainless steel tubes with internal diameters of 4.4 and 6.1 mm. Tests were conducted with mass fluxes of 4400 kg/m2s, exit pressures of 9 bar, length-to-diameter ratios of 25, and exit subcoolings from 65 to 90°C. Test sections were heated directly by DC power, and critical heat flux data were inferred from test-section burnout. The alcohol concentration was periodically checked by draining off a sample and performing a Proton Nuclear Magnetic Resonance scan on the mixture.
At high subcoolings, the mixture exhibited an increase in the critical heat flux over that of pure water. However at low subcoolings there is a decrease in the critical heat flux. The increases in critical heat flux noted with the 1-pentanol mixture in this experiment were not as large as would be expected from saturated pool boiling results published by Van Stralen (1959). Pressure drop data for both the mixture and the pure water also were recorded. The 1-pentanol mixture, in general, exhibited larger pressure drops for the same conditions.