Model Experiment and Theoretical Analysis on Direct Induction Skull Melting

直接感应凝壳熔化法，其中水冷感应线圈直接用作坩埚，具有不受坩埚污染以及高能量效率的优点。然而，该方法的应用仅限于固态电绝缘材料。本研究的目的是扩展该工艺的适用材料，并通过在线圈表面上涂覆绝缘膜来熔化和保持具有固态导电性能的材料，如金属和半导体。为了阐明这一过程的理论基础，考虑到固体和液体状态下电导率和热导率的差异，同时分析了电场和磁场以及温度场。实验证明了该工艺对不锈钢和硅的可行性，表明了固态导电性能，并阐明了该工艺的有效性。 ...更多信息 理论结果。研究发现，在较小的导热系数、较高的传热系数和较低的磁场频率条件下，可以提供较宽的磁场范围以形成稳定的药壳;针对药壳加热时间长、药壳局部过热的问题，提出了一种新的低导热、低导电材料的熔化保压方法。在这种熔化方法中，直接使用水冷感应线圈作为坩埚，并将由高频磁场加热的元件浸没在装料中。在各种操作条件下，即线圈电流、频率和加热元件的半径下，对玻璃进行了实验。建立了一个数学模型来计算过程变量，如线圈和加热元件中的热生成速率以及装料中的温度分布。计算的过程变量与观察到的比较。理论计算结果与实验结果吻合较好，表明了模型的有效性.加热元件中的热产生率由加热元件的半径与电磁穿透深度的比率确定，并且在比率为1.8时具有最大值。少

A direct induction skull melting method, in which a water-cooled induction coil is directly used as a crucible, enjoys an advantage of non-contamination from the crucible together with high energy efficiency. However, the applications of this method are limited to the materials with electrical insulating property in solid state. The aim of this study is to extend the applicable materials of the process and to melt and hold the materials with electrical conducting property in solid state such as metals and semiconductors by coating an insulating film on the coil surface. In order to clarify a theoretical base of the process, electric and magnetic field and a temperature one are simultaneously analyzed by taking account of the differences of electrical and thermal conductivities in solid and liquid states. Experiments demonstrate the feasibility of the process for a stainless steel and a silicon which indicate the electrical conducting property in solid state and clarify the validity of … More the theoretical results. It is found that the conditions of the smaller thermal conductivity, the higher heat transfer coefficient and the lower magnetic frequency, can provide the wider range of the magnetic field to form the stable skull.A new method of melting and holding of a material with low thermal and electrical conductivities is proposed to overcome the problems of long heating period and localized overheat in a charge. In this melting method, a water cooled induction coil is directly used as a crucible, and the elements heated by a high frequency magnetic field are submerged into the charge. Experiments have been conducted on glass under various operating conditions, i.e.the coil current, the frequency and the radius of the heating elements. A mathematical model is developed to calculate the process variables such as the heat generation rates in the coil and the heating elements, and the temperature distribution in the charge. The calculated process variables are compared with the observed ones. The considerably good agreement between the theoretical and experimental results indicates the validity of the model. The heat generation rate in the heating elements is determined by the ratio of the radius of the heating element to the electromagnetic penetration depth and has the maximum value at the ratio of 1.8. Less