bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation Effects on Laminar Mixed Convection in an Inclined Square Duct
Authors: Yan Wei-Mon , Li Hung-Yi 
Published: March 2022

Abstract
A numerical calculation has been performed for the simultaneously developing laminar mixed convection flow and heat transfer for a gray fluid in an inclined square duct with radiation effects. The discrete ordinates method is employed to solve the radiative transfer equation. The coupled momentum and energy equations are solved by the Du Fort-Frankel numerical scheme. In this paper, the major independent parameters are the modified Rayleigh number, mixed convection parameter, conduction-to-radiation parameter, optical thickness, single scattering albedo and wall emissivity. The influences of these parameters on the developments of velocity, temperature, friction factor and Nusselt number are investigated in detail. The axial variations of the fRe and Nu are characterized by a decay near the entrance due to the entrance effect, but the decay is attenuated by the onset of secondary flow. The results for axial distributions of Nusselt number indicate that heat transfer is enhanced by the presence of radiation, but the thermal buoyancy effect is reduced. In addition, the influences are more significant when the conduction-to-radiation parameter and single scattering albedo decrease or the optical thickness and wall emissivity increase.
Closed-Form Solution of Temperature and Heat Flux in Embedded Cooling Channels
Authors: Griggs S. C. , Haji-Sheikh A. 
Published: March 2022

Abstract
An analytical method is discussed for predicting temperature in a material layer with embedded cooling channels to control material temperature. Problems of this type are encountered in the aerospace industry and include high-temperature or high-heat-flux protection for advanced composite-material skins of high-speed air vehicles, thermal laminar flow control on supersonic civil transports, or infrared signal suppression on military vehicles. A Green’s function solution of the diffusion equation is used to simultaneously predict the localized and global effects of temperature in the material and embedded cooling channels. The integral method is used to calculate temperature in the cooling fluid and material simultaneously. This method of calculation preserves the three-dimensional nature of this problem.
Three-Dimensional Natural Convective Flow About a Melting Horizontal Ice Cylinder
Authors: Oosthuizen P. H. , Xu Z. 
Published: March 2022

Abstract
There is some experimental evidence that the flow around a melting ice-cylinder with a large length-to -diameter ratio placed in a large tank of water may not be two-dimensional. The existence of such a three-dimensional flow and the nature of the flow have been experimentally investigated in the present study. Ice-cylinders with a length of 0.5 m and an initial diameter, in most tests, of 53 mm were used. These cylinders were formed from water that contained a small amount of food coloring. The cylinders were suspended horizontally in a large clear plexiglas tank containing water. As the ice cylinders melted, dyed water was released into the flow allowing the flow pattern near the cylinder to be observed. Test were undertaken with the temperature of the water in the tank near room temperature and with the temperature of this water near 4°C. In all cases, it was found that the plume flowing from the ice-cylinder was not a uniform colored sheet as it would be if the natural convective flow about the cylinder was two-dimensional. Instead, this flow was highly three-dimensional, consisting of a series of distinct vortices with axes in the direction of the plume flow. The nature of this flow and the effect of the water temperature on it have been studied.
Unsteady Laminar Thermal Boundary Layer on a Spinning Permeable Isothermal Body
Authors: Kahveci Kamil , Ece Mehmet Cem 
Published: March 2022

Abstract
The initial laminar thermal boundary-layer flow past an impulsively started translating and spinning rotational symmetric, permeable isothermal body is investigated. Velocity components and temperature are expanded in series in powers of time. Leading, first and second order functions are obtained analytically and the third, forth and fifth order functions are determined numerically. Application of the general results to a sphere shows that the unsteady flow field displays complex patterns. Surface blowing is observed to aid body spin in facilitating flow separation. Surface heat flux is enhanced near the front stagnation point and in the reversed flow region and reduced around the point of separation. Surface suction is found to increase the heat transfer while surface blowing decreases it.
A Numerical Study of Three-Dimensional Natural Convection in a Horizontally Heated Enclosure
Authors: Oosthuizen Patrick H. 
Published: March 2022

Abstract
Flow in a rectangular enclosure with a square horizontal cross-section, whose lower horizontal surface is heated and whose upper horizontal surface is cooled and whose vertical side-walls are adiabatic, has been numerically studied. It has been assumed that the flow is laminar and that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces. The unsteady form of the governing equations, written in terms of the vector potential and vorticity vector functions and expressed in dimensionless form, have been solved using a finite-difference procedure based on the equations. The solution was started with no flow in the enclosure. The solution, in general, has the following parameters: The Rayleigh number Ra, the Prandtl number and the size A of the square cross-sectional shape compared to the height of the enclosure. Results have only been obtained for a Prandtl number of 0.7. Results for values of A between 1 and 4 for various relatively low values of Rayleigh number (up to 15000) have been obtained. The results have been used to determine the effect of A on the value of Ra below which there is no fluid motion in the enclosure and to examine the various flow patterns that arise as the value of Ra is increased. The effect of A on the variation of the mean Nusselt number with Ra has also been examined.
Development of a Grid Partial Analytical Solution Method for Solving the Moving Source Heat Conduction Problem
Authors: Ouyang Xing , Bishop Patricia J. 
Published: March 2022

Abstract
The grid partial analytical solution method is a newly developed unconditionally stable explicit numerical solution method for solving parabolic partial differential equations. This method discretizes only the spatial domain and predicts a continuous time dependent function at each spatial nodal point. As such, instead of conventionally predicting the solution from a number set, this method predicts from a functional domain. The typical properties of the grid partial analytical solution method can be summarized as the following:
(1) It predicts a continuous nodal time dependent function rather than a discrete nodal value.
(2) The prediction is unconditionally stable. And unlike any other unconditionally stable finite difference schemes which will lose accuracy when Fourier number becomes large, the proposed method allows single step time marching and unlimited reduction in the spatial step size Δx.
(3) For a fixed time step, the higher value of the grid Fourier number resulting from decreasing Δx, the higher the accuracy is achieved in the predicted solution.
(4) The grid partial analytical solution converges uniformly to the full analytical solution as the spatial truncation error is infinitely decreased by reducing the spatial step size Δx.
This unique characteristic of the analytical treatment of time also makes it possible to treat other time dependent nonhomogeneities involved in heat conduction problem analytically. In this paper, a moving source heat conduction problem is posed and its grid partial analytical solution method developed.
Digital Micromirror Device™: Commercialization of a Massively Parallel MEMS Technology
Authors: Hornbeck Larry J. , Howell T. Russ , Knipe Richard L. , Mignardi Michael A. 
Published: March 2022

Abstract
The Digital Micromirror Device™ (DMD™) is an optical, massively parallel microelectromechanical systems (MEMS) technology that has 500,000 to 1,300,000 rotating digital micromirrors monolithically formed over a CMOS address circuit. Each micromirror acts as a digital light switch. The DMD is the only MEMS light modulator technology to be commercialized in a projection display application. Because the DMD is digital and has numerous moving parts, the commercialization process has had its unique challenges and rewards. This paper introduces DMD technology and presents its R&D history and current focus. The quality, reliability, and manufacturing challenges of this important new display technology also are presented, along with the factors that led to the successful resolution of these challenges.
A High-Sensitivity Micromachined Accelerometer Based on Electron Tunneling Transducers
Authors: Liu C. H. , Reynolds J. K. , Partridge A. , Grade J. D. , Barzilai A. M. , Kenny T. W. , Rockstad H. K. 
Published: March 2022

Abstract
This paper describes the design, fabrication, modeling, and early testing of a new high-sensitivity bulk-silicon micromachined accelerometer based on electron tunneling. The electron tunneling transducer permits detection of small displacements of the proof mass with high electrical response; such a transducer is essential for a high-performance miniature accelerometer. Using bulk-silicon microfabrication technology, a new tunneling accelerometer has been fabricated successfully and operated reliably. The resonant frequency of the proof mass in this tunneling accelerometer is easily modified to satisfy different requirements of sensitivity, dynamic range and bandwidth. This tunneling accelerometer is designed for underwater acoustic application and can be packaged in an 8 cm3 volume with a mass of 8 grams. The measured sensitivity is as high as 200 V/g with a resolution of less than 10 μg/Hz, which is limited by environmental noise, from a few Hz to 270 Hz for a 360 Hz resonant proof mass.
Mechanical Testing of Thicker MEMS Materials
Authors: Sharpe William N. , LaVan David A. , McAleavey Andrew 
Published: March 2022

Abstract
Techniques are described for recording the complete stress-strain curve of nickel microspecimens that are 3 millimeters long and 0.2 millimeters thick and wide. These specimens are fabricated by electrodeposition using the LIGA technique and are typical of the material that would be used in larger microelectromechanical systems (MEMS). Pure nickel deposited in this manner has a yield stress on the order of 300 MPa in contrast to the value of 60 MPa for the bulk material.
The Minimum Meniscus Radius and Capillary Heat Transport Limit in Micro Heat Pipes
Authors: Ma H. B. , Peterson G. P. 
Published: March 2022

Abstract
Based on the momentum conservation and Laplace-Young equations, an analytical expression for the minimum meniscus radius was derived and an expression for the maximum capillary heat transport limit in micro/small heat pipes was obtained. These expressions incorporated the shear stresses at the liquid/solid and liquid/vapor interfaces, contact angle effects, vapor pressure drop, tilt angle, groove dimensions, and channel angle effects. In order to verify the expressions derived herein, comparisons with experimental data from triangular grooves and micro heat pipes were made and demonstrated that these equations can be used to predict the maximum capillary heat transport in the micro/small triangular grooves or micro heat pipes with a higher degree of accuracy and better explain the behavior than previously developed models.
Parabolic Flight Experiments of Spray Cooling With Water and FC-72 Under Reduced and Elevated Gravity
Authors: Yoshida Ken-ichi , Kato Takahisa , Oka Toshiharu , Abe Yoshiyuki , Mori Yasuhiko H. , Nagashima Akira 
Published: March 2022

Abstract
This paper reports on the authors’ latest parabolic-flight experiments (November 1996) of spray cooling. Water and FC-72 (perfluorocarbon) were employed alternately as a test liquid sprayed from a single full-cone nozzle onto a Cr-plated surface of an electrically heated copper block (transient cooling experiments) or onto a transparent In2O3-coated surface of a glass block (steady state experiments in a relatively low superheat region). Each experimental run was accomplished during some 15 seconds through which a reduced gravity condition (∼0.01 times the terrestrial gravity) or an elevated gravity condition (∼2 times the terrestrial gravity) was maintained in the laboratory used — the cabin of an MU-300 aircraft. Cooling curves over a wide range of wall-superheat were obtained with water sprayed at significantly different volume fluxes and with FC-72 sprayed at rather low volume fluxes. It is demonstrated that the gravity dependency of the spray cooling characteristics varies with the spray volume flux and the impinging droplet velocity. Qualitative interpretations of the observed gravity dependency are provided.
Optimization of a Cooling Tower With Ozonation Based on Exergy
Authors: Lu Sun-Shing , Wong Kau-Fui V. , Stoff Larry 
Published: March 2022

Abstract
Cooling tower water treatment is necessary because water has dissolved materials that can deteriorate the operation of the cooling tower. In addition, bacteria in the water can be scattered into the air-conditioned area that can harm people. The first known case of the outbreak of the fatal Legionnaire’s disease in 1976 manifested this fact. There are several methods used in treating cooling water. The application of chemical water treatment is considered mainstream at present, however, its practice is under scrutiny because of environmental considerations. Water treatment with ozonation is selected because it is effective. It is relatively new and thought to be the least controversial of the “new” methods. Other “new” methods include magnetic and electrostatic method, etc. Additionally, many papers and reports have shown that ozonation not only cleans water but also reduces water and power consumption. This is very important especially in places where water and energy resources are not sufficient.
The purpose of this paper is to perform an analysis on cooling tower water treatment according to the first and second law of thermodynamics (exergetic analysis), and try to optimize its operating conditions. The exergetic analysis is better than energetic one because it gives a clearer explanation of the performance, in particular, it takes into consideration the impact of the system on the environment.
Incorporating a District Heating/Cooling System to an Existing Geothermal Power Plant
Authors: Kanoglu Mehmet , Çengel Yunus A. , Turner Robert H. 
Published: March 2022

Abstract
Geothermal energy has been used for power generation, space and process heating, and to a lesser extent, space cooling. However, it is rarely used for cogeneration. This paper shows how a district heating/cooling system can be incorporated to an existing geothermal power plant to make the best use of extracted hot brine.
In the power plant analysis, exergy destruction throughout the plant is quantified and illustrated using an exergy cascade. The primary source of exergy destruction in the plant is determined to be the reinjection of used brine into the ground, which accounts for 48.1% of the total exergy destruction. The overall first and the second law efficiencies of the plant are calculated to be 5.6%, and 28.3%, respectively, based on the exergy of the geothermal fluid at downwell, and 5.7%, and 28.6%, respectively, based on the exergy of the geothermal fluid at wellhead.
A binary system is considered for the heating/cooling district to avoid corrosion and scaling problems. The heating system as designed has the capability to meet the entire needs of the Reno Industrial Park under peak load conditions, and has 30% reserve for future expansion. An absorption system will be used for the cooling of the intended 40% floor space of the industrial park. An economic analysis shows that the incorporation of the district heating/cooling system with 2,785,000 m2 of floor space connected to the geothermal grid appears to be feasible, and financially very attractive. Further, using the returning fresh water from the district heating/cooling system for partial cooling of the binary fluid of the power plant can save up to 15% of the fan work.
The Feasibility of Using a Septic Tank as a Heat Source for Geothermal Heat Pumps
Authors: Hanegan Traci , DenBraven Karen 
Published: March 2022

Abstract
A geothermal heat pump system with three ground coils was installed in a residence on Lake Coeur d’Alene in northern Idaho. A portion of the ground heat exchanger in this system is wrapped around the residential septic tank. The primary purpose of this research was to examine the feasibility of using septic tanks as a heat source for geothermal heat pumps using experimental data collected from this site.
Ground temperatures around this septic tank averaged between −3.5°C and 1.0°C during the 1995–96 heating season. This septic tank is located such that there is little soil surrounding it on all sides. Ground temperatures around the septic coil were influenced more by the outside air temperature than were the other two coils. There was no evidence of the septic tank freezing up or failing to properly function.
Utilizing a septic tank as a heat source for GHP systems is feasible design option if the septic tank is used on a full-time basis. However, the tank should be surrounded on all sides by a large amount of soil and/or insulated from the ground surface to ensure that ground temperatures near the tank remain warm, especially during the cold winter months.
An Analysis of the Major Variables Impacting Performance of Absorption Chillers and Heat Pumps
Authors: Herold Keith E. 
Published: March 2022

Abstract
The major irreversibilities in absorption heat pump technology are associated with the transfer of heat into and out from the machine. By modeling only these irreversibilities, a model is formulated that provides significant insight into the thermodynamics of such cycles. In particular, the shape of the COP curve as a function of heat input temperature does not follow the intuition developed from a fully reversible model. Such a fully reversible model predicts that the COP should rise with the heat input temperature. Instead, the COP of an actual absorption machine falls with a rise in heat input temperature. The explanation of this detail clarifies a number of aspects of the technology and provides insight into such questions as what performance can be expected from future advanced cycles. The model developed here is internally reversible but includes the irreversibilities associated with the external heat transfer processes. Observations made from the model are compared against experience with actual absorption systems to arrive at several generalizations that are useful for absorption machine design.
Effects of Evaporator Frosting on the Performance of an Air-to-Air Heat Pump
Authors: Martínez-Frías Joel , Aceves Salvador M. 
Published: March 2022

Abstract
This paper investigates the effects of frost formation on performance for an air-to-air heat pump. A transient model is used for evaluating frost formation on a parallel-plate heat pump evaporator. The frost formation model is derived by applying the equations of conservation of mass, momentum and energy, as well as some empirical correlations, to calculate the growth and densification of the frost layer. The model has been validated in a previous work by comparison with experimental results.
In this paper, the frost formation model is incorporated into the evaporator subroutine of an existing heat pump model to calculate performance losses due to frosting as a function of weather conditions and time of operation since the last evaporator defrost. The heat pump model takes into account the performance losses due to added pressure drop and heat transfer resistance that result from the growth of the frost layer.
The results show frost formation parameters and heat pump COP as a function of time and ambient conditions. It is determined that there is a range of ambient temperatures and humidities in which frosting effects are most severe, and this range is explored to calculate heat pump operating conditions. The heat pump analysis results are expected to be useful in predicting optimum defrosting conditions, and to evaluate alternative methods for defrosting.
Pool Boiling Heat Transfer Coefficients of Alternative Refrigerants
Authors: Jung Dongsoo , Kim Chong-Bo , Song Kil-Hong , Lee Jun-Kang 
Published: March 2022

Abstract
Nucleate pool boiling heat transfer coefficients (HTCs) of 14 refrigerants are measured from a 19mm o.d. plain copper tube heated by a cartridge heater. All measurements are carried out in the pool temperature of 4∼25°C and in the heat flux of 10∼80kW/m2. Test results show that HTCs of R32, R125, R143a, R152a, and R410A are higher than those of R22. Especially, R32 showed the highest HTCs among all the refrigerants tested. As for R22 alternatives, HTCs of R410A are 50% higher than those of R22 while those of R407C are very similar to those of R22. It is also found that some of the popular pool boiling heat transfer correlations in the literature failed to predict the HTCs of newly developed alternative refrigerants. Hence, a dimensionless analysis is carried out in an attempt to develop a general correlation for all HTCs of pure refrigerants. Thus developed correlation showed an excellent agreement with all experimental data showing a mean deviation of 5.5%.
Approximating Wave Guide Geometries in Gas Pulsation Modeling
Authors: Lai Peter C.-C. , Soedel Werner 
Published: March 2022

Abstract
The four pole concept has been used to analyze gas pulsations in acoustic cavities for a long time. In this study, the four pole parameters for one dimensional (1-D) to three dimensional (3-D) cavities are applied to model a real compressor head with irregular corners and flow obstacles, and a bullet shaped muffler by the idealized rectangular box and circular cylinder approximations. The theoretical results of the transfer functions are calculated from four poles and compared to the experimental data. The comparisons show that certain response frequencies shift between idealized theory and experimental data due to the limitations of an idealized shape analysis for practical applications. In addition, the anechoic termination assumption, which is usually used in compressor discharge modeling, is discussed in this paper. The transfer functions of the above muffler model with different discharge pipe lengths and damping, and horn shaped pipe are simulated and compared. The results represent the typical data measured from experiments.