Measurement of the face temperature during thermal drilling of rocks
The mean face temperature, measured by thermistors during thermal drilling of rocks by dc arc burners with air stabilization of the arc, is between 345 and 563 deg K, depending on the type of rock, the conditions of burner operation, the distance from the face, and the duration of the heat flux's action on the rock; calculation of the initial temperature by Eq. (2) somewhat increases this range.
The temperature increases from the initial value to a certain value which is characteristic for each rock and the burner operation scheme; it then remains constant for the whole drilling period. With an increase in the burner's power, this constant value is reached more rapidly.
The mean face temperature decreases with increasing power of the arc burner, i.e., with increased power of the heat flux.
This method of calculation enables us to determine to a first approximation the coefficient of relative heat transfer from the specimen to the medium under normal conditions.
KeywordsHeat Flux Drilling Rock Fracture Face Temperature Thermal Conductivity Equation
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