Heat transfer characteristics of melting ice spheres under forced and mixed convection

An experimental investigation is conducted to characterize melting and heat transfer during convective melting of an ice sphere in horizontally flowing water The shape changes of melting ice spheres with time at different velocities and supply temperatures of water and at different initial ice temperatures are recorded using a digital video camcorder. From the recorded images, the time variations of local melting rate, local heat transfer coefficient and local Nusselt number at various angular positions are obtained. The effects of water temperature and velocity on these local parameters are analyzed and the total melting rate and average heat transfer coefficient are determined. Guided by a shape factor characterizing the particle shape variation, an empirical correlation for average Nusselt number in convective melting of a solid particle is obtained. The experimental results provide important particle-level information needed to improve the accuracy of numerical models for convective melting of a single particle or packed particles.