This gave valuable background information for comparing the experiments to the model. Snap-off of the plate due to low mechanical strength around the melting temperature may affect the measurement of the penetration depth of the plate. Attempts were also made to measure the temperature in the plate by attaching thermocouples to its surface. The obtained temperature profiles in the plate were compared to the model predictions, but the method needs improvement. A criterion for formation of a shell is formulated and tested against experimental observations.
Qualitative agreement is achieved.
This indicates that the melting rate will be independent of whether a shell is formed or not. Two additional models with only one heat-transfer coefficient are also developed in order to challenge the main model. From this analysis it is found that the use of two heat-transfer coefficients is necessary to describe the system. The model should be of direct interest when feeding rolled scrap into molten aluminium. Improvement of the model can be attained by reconsidering the assumptions made, but then numerical methods must undoubtedly be applied.