Melt Measurement And Numerical Simulation Research Based On Hot Wire Method

The thermal conductivity of a melt is one of the important parameters of its heat transfer characteristics.Research on the thermal conductivity of melts has important applications in many fields such as metallurgy,materials science,and semiconductor industry.It plays an important role in improving production efficiency,optimizing processes,and promoting scientific understanding of high-temperature melt physical processes.The transient hot wire method has simple theoretical model,short measurement time and high accuracy.It is a good method for measuring the thermal conductivity of general fluids and melts.Under microgravity,the convection phenomenon will be weakened,which provides favorable conditions for the measurement of the thermal conductivity of the melt.This paper is a preliminary ground study of measuring the thermal conductivity of melt by hot-wire method under microgravity.Due to the limitation of experimental conditions under microgravity,the sample is in an uneven temperature field,which needs to be studied in the preliminary experiment.In the measurement of transient single-wire method,it is necessary to determine the connection position of the voltage lead.The increase of the resistance of the hot wire itself will change the heating power,and the thermal conductivity of some melts will also change with the temperature.In order to improve the accuracy of measurement,the heat transfer process of the hot wire probe is numerically simulated.It is determined that the voltage lead can be connected at the position 5～7 mm from the end of the hot wire.When the temperature rise of the hot wire is within 4 K,the influence of the hot wire resistance value is within 2 %.For the three samples studied,the heating power should be controlled within 8 W.Then,based on the transient hot wire method,an experimental device for measuring the thermal conductivity of the sample in a tubular furnace was built,and the resistance temperature coefficient of the used hot wire and the temperature field of the tubular furnace were measured.Aiming at the problem of measuring the sample in the uneven temperature field,the simulation is used to correct the measurement results.The average deviation between the experimental thermal conductivity and the reference value is 1.44 % when liquid water is measured in a tubular furnace.After simulation correction,the deviation is reduced to 0.64 %,which verifies the feasibility of simulation correction.Finally,the molten metal indium was measured in a tubular furnace.After simulation correction,the deviation between the thermal conductivity of the sample and the reference value in the literature was reduced from 6.47 % to 0.35 %,and the thermal conductivity of the sample was determined to be 37 W/(m·K).It shows that the proposed simulation correction method improves the accuracy of measurement results.