Conjugate solidification inside a thick mold

This paper reports an experimental investigation of the conjugate solidific ation process inside a thick cylindrical mold using n-octadecane as the pha se change material under constant base temperatures of 5, 10 and 15 degrees C, for different initial liquid superheats of 5, 10 and 15 degrees C, resp ectively, and for subcooled versus non-subcooled wall conditions. The effec t of a thick mold on the solidification process was investigated for two di fferent materials, namely brass and stainless steel. The mold wall and base were subcooled to below the fusion temperature of the phase change materia l (PCM) and an isothermal base temperature was maintained throughout the ex periment. The experimental results showed that the brass mold had a greater solidification rate compared to the stainless steel mold. The solidified m ass fraction is directly proportional to the cube root of time in a cylindr ical mold for the subcooled wall condition. However, for the non-subcooled wall condition, the solidified mass fraction is linearly proportional to th e square root of time. A mold with high thermal diffusivity results in fast er cooling. A mold wall with low thermal diffusivity results in a significa nt temperature gradient along the wall, which results in a sloping phase fr ont. The thermal conditions of the mold wall play a part in the slope of th e phase front. Subcooling of the mold wall appears to give a less pronounce d sloping phase front compared to the preheating of the mold wall. (C) 1999 Elsevier Science S.A. All rights reserved.