Changes in the enthalpy of the ventilation stream during operation of diesel equipment in underground facilities in the permafrost zone

The purpose of this work was to determine the effect of diesel equipment on the thermal regime of mine workings of underground operations in the permafrost zone. The paper analyzes literature sources which state that in mechanized mines and mines, diesel equipment is a determining factor in formation of the thermal regime, and there is a direct relationship between the number of operating machines, their power and the increment of temperature in the mine working. Since certain literary data contradict each other, studies were carried out and calculated dependencies were obtained to determine the increment of enthalpy and temperature in underground facilities during operation of diesel machines and mechanisms. On the basis of qualitative and quantitative analyses, it was established that an increment in the enthalpy (temperature) of the air in the mine workings of underground facilities does not depend on the power and the number of operating diesel units and is fully determined by the initial temperature of the ventilation stream and the thermodynamic efficiency of the engines. It has been established that the increment in the temperature is mainly determined by the efficiency of the operating diesel units, and it increases with an increase in the initial temperature of the ventilation stream: moreover, the higher the efficiency of the units, the smaller is the effect of the initial air temperature on the thermal regime in the mine working. It is shown that even with the minimum thermodynamic efficiency of the diesel equipment equal to 0.4, the temperature increment cannot exceed 6.0°C at the initial positive air temperature, and 5.0°C at the initial negative air temperature in the mine working.