Determination of unidirectional heat transfer coefficient during unsteady-state solidification at metal casting–chill interface Hacı Mehmet S ß ahin a, * , Kadir Kocatepe a , Ramazan Kayıkcı b , Nes ßet Akar a a Gazi U ¨ niversitesi, Teknik Eg ˘itim Faku ¨ltesi, Teknikokullar, Ankara 06503, Turkey b Sakarya U ¨ niversitesi, Teknik Eg ˘itim Faku ¨ltesi, Sakarya, Turkey Received 9 October 2004; accepted 30 March 2005 Available online 11 May 2005 Abstract In this study, the interfacial heat transfer coefficient (IHTC) for vertically upward unidirectional solid- ification of a eutectic Al–Si casting on water cooled copper and steel chills was measured during solidifica- tion. A finite difference method (FDM) was used for solution of the inverse heat conduction problem (IHCP). Six computer guided thermocouples were connected with the chill and casting, and the time– temperature data were recorded automatically. The thermocouples were placed, located symmetrically, at 5 mm, 37.5 mm and 75 mm from the interface. As the lateral surfaces are very well heat isolated, the unidirectional solidification process starts vertically upward at the interface surface. The measured time– temperature data files were used by a FDM using an explicit technique. A heat flow computer program has been written to estimate the transient metal–chill IHTC in the IHCP. The experimental and calculated temperatures have shown excellent agreement. The IHTC during vertically upward unidirectional solidifi- cation of an Al–Si casting on copper and steel chills have varied between about 19–9.5 kW/m 2 K and 6.5– 5 kW/m 2 K, respectively. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Casting–mold interface; Heat transfer coefficient; Al–Si eutectic 0196-8904/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2005.03.021 * Corresponding author. Tel.: +90 312 223 0347; fax: +90 312 212 4304. E-mail address: mesahin@gazi.edu.tr (H.M. S ßahin). www.elsevier.com/locate/enconman Energy Conversion and Management 47 (2006) 19–34