The local characteristics of heat transfer from horizontal tubes immersed in fluidized beds were investigated experimentally. Steady-state heat transfer measurements were obtained in air-fluidized beds of glass beads, both for a single tube and a ten-row bare tube bundle. The test results indicated that local heat transfer coefficients are strongly influenced by angular position and gas flow rate, as well as by particle size and system pressure. The heat transfer coefficients, averaged around the circumference of the tube, exhibited a general tendency to increase with decreasing particle size and increasing system pressure. The heat transfer coefficients for a tube in an inner-row position within the bundle were found to be slightly higher than those for a tube in the bottom-row. Comparison of the average heat transfer coefficient data obtained in this study with some of the existing correlations for heat transfer from horizontal tubes showed that the correlations are unsatisfactory.
Key-words: Titanium alloy, TiAlNb, biocompatible, surgical implant After f ive years of intensive research and development we succeeded in fully developing the new wrought Ti-6Al-7Nb alloy T 67 with an alpha-beta structure, so that it soon reached the stage of production maturity. This titanium alloy, which has been for the first time specially developed for biomcompatible and high-loaded implants, will be used under the trademark PROTASUL® 100 in making various types of femoral component stems for total hip prostheses.Schlüsselwörter: Titan-Legierung, TiAlNb, Körperverträglichkeit, chirurgisches Implantat Nach fünfjähriger Forschungs-und Entwicklungsarbeit konnte die neue Ti-6Al-7Nb Schmiedelegierung T 67 mit Alpha-Beta Struktur erarbeitet werden, wobei auch bald die Produktionsreife erreicht wurde. Diese Titanlegierung wurde erstmals speziell für körperverträgliche, hochbelastbare Implantate entwickelt. Unter der Handelsmarke PROTASUL® 100 wird diese neue Titanlegierung für die Herstellung verschiedener Typen von Schäften für Totalhüftprothesen eingesetzt werden.
The satisfactory prediction of the vapor volume fraction in subcooled boiling depends in large part on the ability to predict the point where a significant amount of net vapor is first formed. A method for the prediction of this point is derived here and compared with experimental measurements at both low and high fluid velocities. The derived relationships for this point include the effect of fluid properties, geometry, and the liquid velocity. A comparison with the empirical formula of Bowring [2] for water is given.
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