Download or read book Heat Transfer Between Surfaces in Contact The Effect of Low Conductance Interstitial Materials Parts 4 and 5 Investigation of Thermal Isolation Materials and Their Application in Bolted Flange Joints written by and published by . This book was released on 1968 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1968 with total page 1498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heat Transfer Between Surfaces in Contact The Effect of Low Conductance Interstitial Materials Part 3 Comparison of the Effective Thermal Insulation for Interstitial Materials Under Compressive Loads written by and published by . This book was released on 1968 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heat Transfer Between Surfaces in Contact The Effect of Low Conductance Interstitial Materials Part 1 Experimental Verification of NASA Test Apparatus written by and published by . This book was released on 1968 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Some Interstitial Materials on the Thermal Contact Conductance written by Jin-Tyan Lin and published by . This book was released on 1970 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Experiments have been conducted to investigate the effect of the interstitial materials at the interface of metals in contact. The test specimens were cylinders, axially aligned and loaded. Specimen materials were 606l-T6 aluminum alloy, and the contact fillers were stainless steel wire screens, aluminum foil, paper, and dielectric greases. The tests were conducted at atmospheric environment. The contact pressure ranged from 25 psi to 600 psi. The mean interface temperature ranged from 100 °F to 200 °F. Surface roughnesses of specimens were from 25 to 35 micro-inches, rms. The results of the investigation reveal that if the contact surfaces are sandwiched with interstitial material, the interface conductance is primarily dependent upon the thermal conductivity of this interstitial material. Some materials such as wire screen have the advantage of being less dependent upon temperature, pressure, and contact surface conditions, compared to bare junctions. The interstitial materials can either increase or decrease the contact resistance. In the case of aluminum foil sandwiched between the aluminum surfaces, the interface conductance increases three times, and sandwiched with greases, increases 10 times as much as that of the aluminum bare junction. On the other hand, if sandwiched with paper the interface conductance is lowered to 70 percent. This paper presents various characteristics of interstitial materials and provides some reliable data for engineering design purposes and further analysis in this field"--Abstract, leaf ii.
Download or read book Thermal Contact Resistance of Selected Low Conductance Interstitial Materials written by Leroy S. Fletcher and published by . This book was released on 1968 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Transient Method of Negligible Internal Thermal Resistance for Determining Thermal Contact Conductance in a Vacuum written by Richard Chuka Oboka and published by . This book was released on 1970 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A transient method for experimentally determining the interface conductance between metallic surfaces in contact is developed. The method applies the theory of negligible internal thermal resistance of one of the materials which form the interface. The method is applicable when the interface conductance is very low, a situation which exists when low conductance interstitial materials are used between contacting surfaces for purposes of thermal isolation. In this investigation, stainless steel wire screens of 10 and 100 mesh were used as interstitial materials between aluminum surfaces in a vacuum environment of 10−5 to 10−6 Torr. The interface pressure ranged from 40 to 200 psi. The roughness of the contacting surfaces ranged from 15 to 25 micro inches, root mean square. The experimental results show that the average thermal conductance obtained by the transient method was from 96.04 to 98.5 % of the steady state thermal conductance when the 10 mesh wire screen was used as the interstitial material and was from 79.28 to 91.13 % of the steady state thermal conductance when the 100 mesh wire screen was used. The results thus show that the method of negligible internal thermal resistance is quite reliable for very low interface conductances"--Abstract, leaf ii.
Download or read book Thermal Spreading and Contact Resistance written by Yuri S. Muzychka and published by John Wiley & Sons. This book was released on 2023-08-09 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal Spreading and Contact Resistance: Fundamentals and Applications Single source reference on how applying thermal spreading and contact resistance can solve problems across a variety of engineering fields Thermal Spreading and Contact Resistance: Fundamentals and Applications offers comprehensive coverage of the key information that engineers need to know to understand thermal spreading and contact resistance, including numerous predictive models for determining thermal spreading resistance and contact conductance of mechanical joints and interfaces, plus detailed examples throughout the book. Written by two of the leading experts in the field, Thermal Spreading and Contact Resistance: Fundamentals and Applications includes information on: Contact conductance, mass transfer, transport from super-hydrophobic surfaces, droplet/surface phase change problems, and tribology applications such as sliding surfaces and roller bearings Heat transfer in micro-devices and thermal spreaders, orthotropic systems, and multi-source applications for electronics thermal management applications Fundamental principles, thermal spreading in isotropic half-space regions, circular flux tubes and disc spreaders, and rectangular flux channels and compound spreaders Systems with non-uniform sink plane conductance, transient spreading resistance, and contact resistance between both non-conforming and conforming rough surfaces Providing comprehensive coverage of the subject, Thermal Spreading and Contact Resistance: Fundamentals and Applications is an essential resource for mechanical, aerospace, and chemical engineers working on research in the fields of heat transfer, thermal management of electronics, and tribology, as well as thermal engineers and researchers in the field of thermal physics.
Download or read book Heat Transmission Measurements in Thermal Insulations written by R. P. Tye and published by ASTM International. This book was released on 1979-12 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Isolation with Low Conductance Interstitial Materials Under Compressive Loads written by Paul Anthony Smuda and published by . This book was released on 1969 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spacecraft Thermal Control Handbook written by David G. Gilmore and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation This is a revised and updated of (1994) and has been expanded to discuss interplanetary spacecraft as well as Earth- orbiting satellites. The work is presented as a compendium of corporate knowledge in the field of thermal control of uncrewed spacecraft and was written for thermal engineers of a range of experience levels. After discussing general issues and historical design approaches chapters examine current thermal control hardware, the thermal design and testing process, and emerging thermal technologies. Annotation c. Book News, Inc., Portland, OR (booknews.com).
Download or read book An Investigation of Radiative Heat Transfer in Fibrous Thin Sheets written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fibrous materials possess desirable heat transfer characteristics and are used in many thermal applications including thermal insulations. Radiant heat transfer thru such materials is very important even at moderate temperatures. Thus, a fundamental understanding of the radiative heat transfer through such materials is necessary and allows better evaluation of its insulation capabilities. Due to the complex mathematical formulation of the theory of radiative heat transfer, the solution of its equations is consequently as complicated. Computational fluid dynamics (CFD) simulations provide a practical method to understand the response of fibrous media to this electromagnetic irradiation. In this study, for the first time, the Surface-to-Surface model is used to investigate the response of fibrous materials to radiative heat transfer. The unsteady state heat transfer equations are solved for the temperature and heat flux in and around the fibers that constitute a nonwoven fibrous media. Of particular interest here is the effect of fiber diameter, fiber conductivity, and materialÃØâ'Ơâ"Øs Solid Volume Fraction (SVF) in heat transfer through the material. For a fixed fiber diameter, it is shown that the larger the solid volume fraction, the lower is the materialÃØâ'Ơâ"Øs temperature. It is also shown that the fiber conductivity has a significant influence on the radiative heat transfer in nonwoven materials. Our simulation results indicate that the average fiber temperature is directly influenced by SVF, fiber conductivity, and fiber diameter. However, SVF has been observed to have the greatest influence followed by the fiber conductivity, and lastly fiber diameter. The web thickness effect was also simulated. The materialÃØâ'Ơâ"Øs average temperature decreased with increasing thickness for fixed SVF and fiber diameter. Experimental work has also been conducted to verify the simulation results. Comparison between curve fitting of simulation and experimental data showed a.
Download or read book Thermal Transmission Measurements of Insulation written by Ronald Phillip Tye and published by ASTM International. This book was released on 1978 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bridging Conduction and Radiation written by Vazrik Chiloyan and published by . This book was released on 2015 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Near field radiation transfer between objects separated by small gaps is a widely studied field in heat transfer and has become more important than ever. Many technologies such as heat assisted magnetic recording, aerogels, and composite materials with interfacial transport involve heat transfer between surfaces with separations in the nanometer length scales. At separations of only a few nanometers, the distinction between classical thermal conduction and thermal radiation become blurred. Contact thermal conduction is understood through the means of interfacial transport of phonons, whereas thermal radiation is understood by the exchange of heat through the electromagnetic field. Typically conductance values in the far field radiation regime are on the order of 5 W/m2K, whereas contact conductance is on the order of 108 W/m2K. While near field radiation experiments have reached separations down to on the order of 10 nm and measured 104 W/m2K, there are still 4 orders of magnitude change that occurs over 10 nm of separation. However to this day, there does not exist a single unified formalism that is able to capture the relevant physics at finite gaps all the way down to the contact limit. The success of the continuum electromagnetic theory with a local dielectric constant has allowed accurate modeling of thermal transport for materials separated by tens of nanometers. The validity of this approach breaks down at the contact limit as the theory predicts diverging thermal conductance. The nonlocal dielectric constant formalism has successfully been applied to correct this error and predict transport at nanometer separations for metals and nanoparticles. However, success has been limited for deriving nonlocal dielectric constants for insulators as it is both theoretically and computationally more challenging and requires accurate atomic modeling to retrieve a valid continuum dielectric that reproduces the response of the system. In this work, the continuum approach is avoided and an approach is taken which more closely resembles the conduction picture, by performing atomistic modeling of the thermal transport between two semi-infinite media. The interatomic forces of both short-range chemical bonding forces and long ranged electromagnetic forces are included in an atomistic Green's function formalism in order to accurately calculate thermal transport at finite gaps down to the contact limit. With a single, unified formalism the bridge between conduction and radiation is finally achieved.
Download or read book Thermal Contact Conductance written by Chakravarti V. Madhusudana and published by Springer Science & Business Media. This book was released on 2013-09-24 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work covers both theoretical and practical aspects of thermal contact conductance. The theoretical discussion focuses on heat transfer through spots, joints, and surfaces, as well as the role of interstitial materials (both planned and inadvertent). The practical discussion includes formulae and data that can be used in designing heat-transfer equipment for a variety of joints, including special geometries and configurations. All of the material has been updated to reflect the latest advances in the field.
Download or read book Thermal Joint Conductance of Conforming Rough Surfaces written by Adel Abdel-Halim Hegazy and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work dealt with the problem of predicting contact, gap and joint conductances between conforming rough surfaces. The main purpose of the work was to investigate the effect of surface micro-hardness variation upon the prediction of thermal interface conductances under the first load cycle. A survey of the literature revealed that the title problem has received very little attention in the past three decades, especially from the thermal viewpoint. An investigation of surface micro-hardness variation was carried out. The investigation revealed that most engineering surfaces exhibit micro-hardness variation which depends upon the material type and the machining process. These findings were confirmed by a series of Vickers micro-hardness measurements for several engineering materials. A semi-general micro-hardness variation for these materials has been proposed which should be useful to thermal analysts. The theoretical thermal conductance models used in this work are those of Yovanovich and his co-workers. These models were reviewed and a mechanical model was proposed to estimate the appropriate contact hardness value required for accurate thermal predictions. The mechanical model was applicable for practical engineering joints and is a function of the surface parameters and the micro-hardness variation of a particular joint. An extensive experimental program was carried out employing different materials to verify the theoretical models over a broad range of surface roughnesses, thermophysical properties, micro-hardness variations and contact pressures. More than 400 contact conductance data points for Nickel 200, Stainless Steel 304, Zircolay-4 and Zirconium-2.5wt%Nb joints confirmed the validity the mechanical and contact conductance models. Also, experimental data for stainless steel joints in Nitrogen and Helium environments were obtained. The agreement between the measured and predicted joint conductances was excellent for Nitrogen data but seemed to break down for Helium. The deviations between some of the experimental data and the theoretical predictions were discussed. The discussion has emphasized the importance of the joints' geometric and thermophysical parameters which affected the predictions in vacuum or gaseous environments. The present work explained the apparent contradictory results obtained by various investigators for similar materials. It showed also that accurate thermal predictions depended more than had been realized upon the appropriate micro-hardness value which must be determined from the micro-hardness variation. The present work confirmed the validity of the investigated models.
Download or read book Interface Thermal Conductance with Metal Screens as Interstitial Material written by William Edward Stewart (Jr.) and published by . This book was released on 1970 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis reports the results of an experimental investigation to determine the thermal conductance at the interface of metal specimens separated by wire mesh. Sets of metal specimens of copper, 2024-T4 aluminum, and 304 stainless steel were used. The specimens were cylindrical, axially aligned, and hydraulically loaded. All tests were conducted in an air environment. Pressure applied to the specimens ranged from 50 to 500 psig. Surface roughness of the interfaces varied from 5 to 20 micro inches. The wire mesh separators were of 304 stainless steel in 20, 30, 40, and 50 mesh. Results of the experiments show that: a) thermal conductance increases with an increase in mesh number and the corresponding increase in the number of contact points, b) an increase in contact pressure will increase thermal conductance in all cases and, c) at a given pressure and with a given mesh stainless steel screen, the specimen materials in order of decreasing interface conductance are: aluminum, copper, and stainless steel"--Abstract, leaf ii.
