微波加热金属液体的实验研究

Experimental research into the heating of liquid metal with microwave

研究微波加热液态金属的升温特征,在MobileLab-W-R型微波工作站中进行了微波直接加热铜液和铁液的实验研究,实现了微波直接加热铜液和铁液实验,对比研究了微波直接加热和间接加热铜液与铁液的加热效果,并研究了微波功率、金属液质量、温度等对微波直接加热效果的影响,探讨了微波直接加热金属液体的机理.结果表明,微波可以以较快的升温速度直接加热铜液和铁液,且升温速率与微波加热功率呈近似线性递增关系;在相同微波直接加热条件下,同等质量的铜液和铁液的升温速度相近,但不同质量铁液加热时,由于其表面积、微波场强分布等因素的影响,铁液质量对微波加热效果的影响没有明显的线性关系.理论分析认为,铜和铁在熔化后电阻率增大,磁导率明显下降,导致微波在铜液和铁液内部的趋肤深度显著大于固态铜和铁;电导损耗是实现微波直接加热液态金属的主要机制,液态金属可通过电子与原子核碰撞、表面快速更新、内部缺陷阻碍电子运动、原子运动及碰撞等形式吸收微波,将微波能量转化为自身热量.

Characteristics of molten metal heated with microwaves were the focus of this study.A series of experiments on the direct microwave heating of molten copper and molten iron were conducted in a MobileLab-W-R microwave workstation;both metals were effectively heated by direct microwaves.Effects of indirect versus direct heating were comparatively analyzed using different types of heating chambers.The direct heating method was then further investigated,taking microwave power,mass of molten metal,and temperature into consideration.The mechanism of direct microwave heating of molten metal was discussed.The results show that microwave can directly heat molten iron and molten copper at high rates that increase linearly with increasing microwave power.Heating rates of molten iron are similar to those of molten copper at constant mass and microwave power.However,the mass of molten iron has no clear linear relationship with heating rates due to the involvement of other factors,such as surface area of the molten iron and distribution of the microwaves.According to the theoretical analysis,when the states of copper and iron are transferred from solid to liquid,their resistivities increase,but their permeabilities drop significantly.As a result,the skin effect depths of microwave in molten copper and iron are clearly larger than those in the solid metals.Conductivity loss is the main mechanism of achieving direct microwave heating of molten metal.Microwave energy can be absorbed in four ways:collisions between electrons and nucleus,rapid liquid surface renewal,hindering of internal defects of electron movement,and atom movement and collision.Absorbed microwave energy can be transferred into the internal energy of the molten metal.