Error Analysis Feasibility Study On Thermocouple-based Monitoring Of The Hot Spot In The Goaf Model

Thermodynamic disasters are one of the main threats to coal mine safety production.In order to improve the level of prevention and control of thermal power disasters of coal mines in China,domestic scholars have built many simulation experimental devices.However,due to the self-characteristics such as the axial heat conduction of the thermocouple,the temperature measurement usually has a large error,and it it difficult to accurately reflect the evolution of the thermal dynamic disaster in the goaf.Relying on the national key research and development project "Coal mine thermal prower disater early warning technology and equipment",this paper aims at accurately measuring the temperature of coal and rock accumulation conditions in goaf by thermocouple,and adopts the research method of combining theoretical analysis with numerical simulation,specially carries out the appllication research of real-time temperature and high-precision measurement methods.The main achievements are:(1)Based on the investigation of relevant experimental testing technology,combined with the theoretical analysis of the temperature error of the high temperature point thermocouple in the simulated goaf,it is concluded that the diameter of thermocouple,different insertion angles and length of exposed end are the main factors affecting the accuracy of temperature measurement.(2)The numerical simulation of the seepage heat transfer and thermocouple temperature measurement accuracy of particle accumulation is carried out.The results show that the larger the diameter of thermocouple,the more obvious the interference to the internal heat flow field of the model,and the greater the heat along the thermocouple itself,the thermocouple temperature measurement error is large.Based on the seepage simulation results of granular accumulation,the coefficients of the Blake-Kozeny empirical formula are revised from 150 to 165.(3)Based on the porous medium model,using the modified Blake-Kozeny formula and numerical simulation method,five groups of goaf thermocouple temperature measurement examples are calculated.The feasibility of the high temperature measurement technology in the simulated goaf was confirmed and the way to improve the accuracy of temperature measurement.