Research And Apply Of Surrounding Rock Unsteady Heat Transfer Coefficient In Mine Roadway

Along with the increase of mining depth of coal resources, the ground temperature rising,the heat-harm which caused by the ground temperature has become a problem that affects themine safety and efficient production is urgently to be solved. Heat dissipation of surroundingrock occupies large proportion in the mine heat sources, therefore, aimed at the importantparameter which decides the heat dissipation change of surrounding rock--research onunstable heat transfer coefficient is the basis of the heat dissipation of surrounding rock andwind temperature prediction in roadway, which has important theoretical and practical value.This paper studied on unstable heat transfer coefficient by the research methods that combineswith theoretical analysis, numerical calculation and visualization software design, emphasison theoretical analysis, solving, verification, correction, variation, regression analysis of theunstable heat transfer coefficient and visualization application in rock heat dissipationcalculation.On the theoretical analysis and solving process of the unstable heat transfer coefficient,this paper demonstrates the definition type of the unstable heat transfer coefficient, in terms ofthe hypothesis condition that intake air temperature and relative humidity in a constant state,based on the theory of special form of Sturm--Liouville equation, analyzed the feasibility oftemperature gradient became to zero in control-heat circle, used the variables separationmethod, deduced the temperature-distribute function in the surrounding rock and thetheoretical solution of unstable heat transfer coefficient under tunnel unsteady heat transfercondition.Through the MATLAB calculation and analysis, found the theoretical solution in thispaper has high inosculation compared with CenYanJiang’s fitting approximation formulaunder the same parameters, especially, after long-term ventilation the difference betweenthem is less than0.01W/(m2·℃), nearly the same. According to the theory of heat-masstransfer between humid wind and roadway rock, introduced the coefficient of heat-humidityratio to correct the theoretical solution of unstable heat transfer coefficient, ensured the resultswith higher accuracy. Through numerical calculation, analyzed the vary distribution of krelated with Fo and Bi, came to following conclusion:(1)When Fo to be a fixed value, k increases with the increasing of Bi.(2) The condition of critical Fourier number less than1, F and Bi inflection points can beused as evaluation standard that whether cooling or not and cooling effect in roadway.(3) After a long-term stability ventilation, k will be within0.3~0.4in any roadway. (4) The trend of k change consistently under seveal sets of Bi, it changes drastically whenFo is relatively small, almost presents in a straight line to reduce, when Fo>10the tendchanges slowly, nearly in a horizontal line.According to the theory of dimensionless unstable heat transfer coefficient, used theMATLAB software for the multivariate nonlinear regression analysis, calculated theregression model of the dimensionless unstable heat transfer coefficient. The critical Fouriernumber equal to1as the critical value, put forward segmentation algorithm theory of heattransmission in surrounding rock, improved the heat dissipation calculation method ofsurrounding rock. Through the Delphi software, developed the calculation software of rockheat dissipation that running in the Windows system.