EXPERIMENTAL STUDY ON THE EFFECT OF LIQUID METAL SUPERHEAT AND CASTING HEIGHT ON INTERFACIAL HEAT TRANSFER COEFFICIENT

Abstract

In this article, the interfacial heat transfer coefficient (IHTC) is investigated as a function of superheat temperatures (100°C, 150°C, and 200°C) and casting heights (100, 150, and 200 mm). The experiments were conducted for a liquid alloy (Al-Si 12.9%) on water-cooled copper chill during vertically upward solidification of a eutectic Al-Si alloy casting. A finite difference method (FDM) is applied for the numerical used for solution of inverse heat conduction problem (IHCP), the so-called Beck's method. Computer-guided thermocouples were connected with the chill and casting, at six positions and the time-temperature data were recorded automatically. As the lateral surfaces are very well heat isolated, the unidirectional solidification process started vertically upward at the interface surface. The measured time-temperature data files were used by FDM using explicit technique. The experimental and calculated temperatures have shown excellent agreement. The IHTC increases as superheat temperatures increases. However, the casting height (100, 150, and 200 mm) has no significant effect on the IHTC. It changed only maximum peak values of the IHTC and increased air gap formation time with increasing casting height.

Keywords:

• casting-mold interface
• heat transfer coefficient
• Al-Si eutectic alloys
• superheat

ACKNOWLEDGMENT

This work is supported by the research fund of the Gazi University, Projects #: 07/2002-08.

Notes

*Solidus Temperature 849 K.

**Liquidus Temperature 850 K.