The Russian fleet of water and steam mine heaters is gradually being replaced by the electric and gas air heaters. New automated systems can maintain the set temperature of the mine air without noticeable deviations. This creates the basis for optimizing the operating point of mine air heating systems.
When the mine is dry and there is no lifting machine, there is no fear for ice formation. Humidity of the mine air is not standardized. The optimal position of the operating point is determined by only one parameter — temperature. Its limit value tC = 2 °C is set by the Russian rules for occupational safety in the mines.
In a wet mine, the main control factor is the prevention of ice formation. To interpret the experimental data on this phenomenon, in  a diagram of the states of mine air was constructed in the coordinates «temperature — specific enthalpy».
As a result, it was established that the optimal position of the operating point for a wet mine is determined by only one parameter of the state of the mine air — specific enthalpy. The area of possible ice formation on the diagram is limited by the horizontal line hC = constant. The value of the constant depends on the barometric pressure at the critical point where the groundwater seeps through the shaft support. In the area of high-enthalpy regimes (hC constant), the ice formation in a wet mine is not observed.
Such an interpretation of the experimental data allowed to determine in an explicit form the dependence of the optimal mine air temperature on weather conditions and the method of heating (direct or indirect). Theoretical norms of annual heat consumption for the dry and wet mines are compared. The energy efficiency of heating a wet mine with the help of gas recuperative and mixing air heaters is estimated. From the standpoint of safety of the operation of hoisting machines, the experience is considered concerning weather regulation of the operating point of the mine air heating systems.
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