Test of Thermo-Physical Property Parameters of Solid Material Based on Laser Point Heat Source Unsteady-State Heat Transfer Model

Abstract

Based on the laser point heat source unsteady state transfer model, a novel method to gain thermo-physical parameters of isotropic solid materials is proposed. The enantiomorphous heat-source theory is introduced to calibrate the influence of adiabatic boundary on temperature rise of the measuring points, and a mathematical model is established. The thermal conductivity and thermal diffusivity of the material are calculated by numerical solution combined with computer programming, and a thermo-physical testing system is developed. The low vacuum environment in the sample container is obtained by using a vacuum pump. The laser generator emits a laser beam to heat a corner of the sample, and the variation of temperature on the upper surface of the sample measured by the temperature sensor is monitored by the wireless signal transmitting unit. The thermophysical properties of borosilicate glass (Pyrex7740), marble, diatomite firebrick, silica brick, and zirconium brick are comprehensively tested. The results show that the relative deviation between the test values of the first four samples with a relatively low thermal conductivity and the reference value is not more than 2.76%, and the test accuracy is higher. The relative deviation between the test values of the zirconium brick with a relatively large thermal conductivity and the reference value reaches 6.38%, and the test accuracy is lower. Uncertainty analysis of the test system shows that as the thermal conductivity of the tested sample increases, the credibility between the test value and the true value decreases, indicating that the device is more suitable for solid materials with a thermal conductivity less than 3.0W/(m·K).

Keywords

• laser point source
• non-steady state heat transfer model
• enantiomorphism heat-source theory
• solid material
• thermo-physical property