Naslov
DEPENDENCE OF THE HEAT TRANSFER COEFFICIENT AT QUENCHING ON DIAMETER OF CYLINDRICAL WORKPIECES

Autori
Liščić, Božidar ; Singer, Saša ; Beitz, Hartmut

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of the 18th IFHTSE Congress / - Rio de Janeiro, 2010, 1-10

Skup
18th Congress IFHTSE

Mjesto i datum
Rio de Janeiro, Brazil, 26.07.2010. - 30.07.2010

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Quenching; Heat transfer coefficient; Inverse heat conduction calculation

Sažetak
For computer simulation of a quenching process, the fundamental prerequisite is to have the relevant heat transfer coefficient (HTC) calculated as function of work-piece'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 of 20 mm, 50 mm and 80 mm diameter are used. The cooling curve was measured always at 1 mm below the surface of the probe. Special care has been taken to keep all other factors (design of the probes, temperature measurement, quenching conditions and calculation procedure), which can influence on the calculated HTC, constant, in order to assure that the only variable is the diameter of the probe. Supposing a radially symmetrical heat flow at half length of the probe, the HTC was calculated using 1-D inverse heat conduction method. The unexpected striking result of this investigation is the fact that for biggest probe diameter (80 mm) the calculated HTC as function of surface temperature does not show the film boiling phase. A plausible explanation of this effect is given, based on the critical heat flux density. The possibility to establish a simple fixed relation (a correction factor) between the HTC and the diameter of cylinders is discussed.

Izvorni jezik
Engleski

Znanstvena područja
Matematika, Strojarstvo

POVEZANOST RADA