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Author: Raymond Ellory Taylor Publisher: ISBN: Category : Heat Languages : en Pages : 65
Book Description
The report discusses the progress on a program for evaluating direct electrical heating methods for high temperature thermal conductivity determinations. A multi-purpose apparatus used in the evaluation of these methods, has generated data simultaneously on thermal conductivity, electrical resistivity, total hemispherical emittance and spectral emittance (0.65 microns) to 1800 K under high vacuum. Problems associated with emittance are extremely important in thermal conductivity determinations at high temperatures using direct heating methods. Great care must be taken to insure that the emittance remains constant over the central portion of the test specimen. The mathematical techniques used to compute thermal conductivity from the experimental data were explored and considerably advanced. These techniques eliminated the need for mathematical approximations which severely limit the region of applicability. One of these techniques was easily extended to the general case which includes three conductivity methods as special cases. Therefore, the need to match certain experimental conditions was eliminated. The inclusion of temperature-dependent physical properties was also readily included in this technique. The mathematical techniques also yielded temperature profiles which could be compared to the experimental profiles. (Author).
Author: Raymond Ellory Taylor Publisher: ISBN: Category : Heat Languages : en Pages : 65
Book Description
The report discusses the progress on a program for evaluating direct electrical heating methods for high temperature thermal conductivity determinations. A multi-purpose apparatus used in the evaluation of these methods, has generated data simultaneously on thermal conductivity, electrical resistivity, total hemispherical emittance and spectral emittance (0.65 microns) to 1800 K under high vacuum. Problems associated with emittance are extremely important in thermal conductivity determinations at high temperatures using direct heating methods. Great care must be taken to insure that the emittance remains constant over the central portion of the test specimen. The mathematical techniques used to compute thermal conductivity from the experimental data were explored and considerably advanced. These techniques eliminated the need for mathematical approximations which severely limit the region of applicability. One of these techniques was easily extended to the general case which includes three conductivity methods as special cases. Therefore, the need to match certain experimental conditions was eliminated. The inclusion of temperature-dependent physical properties was also readily included in this technique. The mathematical techniques also yielded temperature profiles which could be compared to the experimental profiles. (Author).
Author: Reginald W. Powell Publisher: ISBN: Category : Heat Languages : en Pages : 112
Book Description
Direct electrical heating methods possess desirable features for determinations of thermal conductivity values to high temperatures. Since unreliable data have been obtained by previous workers using these methods, a systematic evaluation of the various techniques was initiated. An apparatus capable of providing a variety of thermal/electrical boundary conditions to a single specimen as prescribed by particular techniques was designed and fabricated. With this apparatus thermal conductivity, and other thermophysical properties, can be determined on a single specimen by various methods, permitting direct evaluation and comparison of the results. In connection with this experimental effort, the theoretical models of the methods and analyses of the conditions which must be met in the experimental apparatus are being studied. The ultimate objective of the program is to devise a technique(s) suitable for determinations to temperatures of the order of 2500 C, utilizing test specimens of simple geometry and minimum volume. (Author).
Author: Raymond Ellory Taylor Publisher: ISBN: Category : Heat Languages : en Pages : 71
Book Description
Progress on a program for evaluating direct electrical heating methods for high temperature thermal conductivity determinations is presented. Recent modifications, which increased the temperature capabilities of the apparatus, protected the samples from contamination and improved the accuracy and simplicity of the measurements, are described. A method for calculating the thermal conductivity using any three temperature versus position data points (3-point method) of a temperature profile was devised. Using this 3-point method, hundreds of conductivity values can be calculated per temperature profile. Computational schemes which utilize multiple data points or the output of the 3-point program are being developed. Substantial improvement in the accuracy and reproducibility of the computed thermal conductivity values has been obtained using these schemes. In addition, values for the Thomson coefficient are derived. Data on thermal conductivity, total hemispherical emittance, spectral emittance (0.65 microns), electrical resistivity, and Thomson coefficients for tantalum, ATJS graphite and tungsten to about 2700 K are presented. (Author).
Author: Air Force Materials Laboratory (U.S.) Publisher: ISBN: Category : Materials Languages : en Pages : 186
Book Description
Technical reports published by the Air Force Materials Laboratory during the period 1 January 1968-31 December 1968 are abstracted herein and indexed by branches of the laboratory, technical subject matter, investigator, project monitor and contractor. Reports on research conducted by the Air Force Materials Laboratory personnel as well as that conducted on contract are included.
Author: David C. Larsen Publisher: Springer Science & Business Media ISBN: 1468442651 Category : Technology & Engineering Languages : en Pages : 606
Book Description
The International Thermal Conductivity Conference was started in 1961 with the initiative of Mr. C. F. Lucks and grew out of the needs of researchers in the field. From 1961 to 1973 the Confer ences were held annually, and have been held biennially since 1975 when our Center for Information and Numerical Data Analysis and Synthesis (CINDAS) of Purdue University became the permanent Spon sor of the Conferences. These Conferences provide a broadly based forum for researchers actively working on the thermal conductivity and closely related properties to convene on a regular basis to ex change their ideas and experiences and report their findings and results. The Conferences have been self-perpetuating and are an example of how a technical community with a common purpose can transcend the invisible, artificial barriers between disciplines and gather togeth er in increasing numbers without the need of national publicity and continuing funding support, when they see something worthwi1e going on. It is believed that this series of Conferences not only will grow stronger, but will set an example for researchers in other fields on how to jointly attack their own problem areas.
Author: Raymond Ellory Taylor
Author: Raymond Ellory Taylor
Author: Reginald W. Powell
Author: Migirdic Nalbantyan
Author: Raymond Ellory Taylor
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Author: W. T. K. Johnson
Author: Air Force Materials Laboratory (U.S.)
Author: David C. Larsen
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