Dependence of heat transfer coefficient at quenching on diameter of cylindrical workpieces

Liščić, Božidar and Singer, Saša and Beitz, Hartmut (2011) Dependence of heat transfer coefficient at quenching on diameter of cylindrical workpieces. = Dependence of heat transfer coefficient at quenching on diameter of cylindrical workpieces. International Heat Treatment and Surface Engineering, 5 (3). pp. 101-105. ISSN 1749-5148. Vrsta rada: Original scientific paper. . .

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Abstract

For computer simulation of a quenching process, the fundamental prerequisite is to have the relevant heat transfer coefficient (HTC) calculated as a function of the workpiece's surface temperature and time respectively. In order to calculate the HTC experimental measurement of the temperature-time history (cooling curve) near the workpiece surface is necessary. In this investigation, cylindrical probes with diameters of 20, 50 and 80 mm are used. The cooling curve was always measured 1 mm below the surface of the probe. Special care has been taken to keep all other factors (e.g. design of the probes, temperature measurement, quenching conditions and calculation procedure), which can influence the calculated HTC, constant, in order to ensure that the only variable is the diameter of the probe. Assuming a radially symmetrical heat flow at the half length of the probe, the HTC was calculated using one-dimensional inverse heat conduction method. The unexpected striking result of this investigation is the fact that for the probe diameter (80 mm) the calculated HTC as a function of surface temperature does not show the film boiling phase. A plausible explanation for this effect is given, based on the critical heat flux density. The possibility of establishing a simple fixed relation (a correction factor) between the HTC and the diameter of cylinders is discussed. © 2011 IHTSE Partnership.

Item Type: Article (Original scientific paper)
Keywords (Croatian): Calculation procedure; Cooling curve; Correction factors; Experimental measurements; Film boiling; Inverse heat conduction; Inverse heat conduction methods; Quenching process; Surface temperatures; Work pieces; Atmospheric temperature; Computer simulation; Heat conduction; Heat flux; Heat transfer coefficients; Phase diagrams; Quenching; Surface properties; Temperature measurement; Probes
Subjects: NATURAL SCIENCES > Mathematics
TECHNICAL SCIENCE
Divisions: 1000 Department of Materials
Indexed in Web of Science: No
Indexed in Current Contents: No
Citations SCOPUS: 0 (22.4.2015.)
Date Deposited: 22 Apr 2015 12:05
Last Modified: 22 Apr 2015 12:05
URI: http://repozitorij.fsb.hr/id/eprint/3787

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