Design And Development Of Thermophysical Properties Testing Device For Solid Materials Based On Laser Point Heat Source

The thermophysical properties of materials are the basic parameters to characterize their heat carrying capacity.The heat carrying capacity of different kinds of materials vary greatly,and their precise thermophysical properties are usually obtained by experimental methods.At present,the research on the testing methods of thermophysical properties of materials and the design of their devices have become a basic subject,which has drawn more attention.Based on the unsteady heat transfer model in the theory of solid heat conduction,a new method for measuring the thermophysical properties of solid materials based on the unsteady heat transfer model of laser point heat source was proposed in this paper.The enantiomorphous heat-source theory was introduced to calibrate the influence of adiabatic boundary on temperature rise of the measuring points,then the mathematical model was established.Using numerical solutions and combining computer programming to calculate the thermal conductivity,thermal diffusivity and specific heat capacity of materials,a thermophysical testing system was developed.The device sample container was sealed,and the adiabatic boundary achieved by pumping out air to achieve low vacuum environment.During the experiment,the foot of the plate sample was ground flat and coated with graphite powder to form the action area of the laser point heat source.The patch type temperature sensor was disposed on the upper surface of the sample to detect the temperature change by the wireless signal transmitting unit.Borosilicate glass(Pyrex7740)was selected as tested samples.The thermophysical properties were consistent with the reference literature values,which verified the validity of the measurement results of the testing system.The results of comprehensive monitoring of thermophysical properties of marble,silica brick and diatomite refractory bricks showed that the deviation between the calculated thermal conductivity of each material and the reference value was less than 5%.At the same time,the stability of the testing results of diatomite refractory bricks with the lowest thermal conductivity was significantly better than other materials.Evaluating the uncertainty of the thermal conductivity of marble and borosilicate glass showed that the uncertainty of marble was higher,while the uncertainty of thermal conductivity of borosilicate glass was lower.Therefore,the device is more suitable for testing solid materials with low thermal conductivity(generally thermal conductivity is less than 3.0W/(m?K)).Also,the smaller the thermal conductivity of the sample to be tested,the lower the uncertainty.Figure[35] Table[14] Reference[63]...