Study On Precooling Undergroud Inletairflow Utilizing The Low Temperature Effect Of Rock Stratum

This paper first analyzes the domestic and international status quo of high temperature in mines and its harm, indicates that the high underground temperature badly threatens the safety of mine production and the physical and mental health of miners, the harm of high undergroud temperature has become one of the major disasters which constrain the sustainable development of underground mines.The high temperature and humidity in the mine operating environment will not only harm the health of miners by inducing various diseases, but also endanger the safety of mine production, lower labor productivity of workers in turn affect the economic benefits of mining enterprises. Thus, cooling air to improve air conditions underground mine has become an important work to guarantee safe production of mine.This paper intruduces some cooling measures in detail, including ventilation cooling, artificial refrigeration cooling, artificial cold storage cooling, pre-cooling using low temperature effect of rock stratum and individual protection, sums up the study status and development level of domestic and foreign scholars on heat exchange between airflow and wall rock in underground mine, according to the heat exchange principle between airflow and wall rock, derives a simplified model of heat exchange between airflow and wall rock. Taking the applicability of the theoretical modle into account, this model describes heat exchange process between airflow and wall rock in horizontal laneway as well as in oblique and vertical laneways.The key of using the low-temperature effect of rock stratum to pre-cooling the inlet airflow is calculating the quantity of heat exchange between airflow and wall rock of which the accuracy and complexity directly relates to the rationality and economy of mine cooling design. Because rock stratum is anisotropic, rock temperature and the temperature of inlet airflow are changing with seasons and time, it is a very complicated problem to calculate the quantity of heat exchange between airflow and wall rock. Because most of the traditional calculatition methods need for large cumbersome numerical calculation, and the results are not necessarily reliable. In this paper, because air humidity in abandoned laneways which are usually used as precooling laneways is not high in general, to simplify the modle, when calculating heat and wet exchange between wall rock and airflow, ignore wet exchange between airflow and wall rock and the influence of other heat sources. On the basis of heat exchange theories, using the principles of heat transfer and cooled zone theory of laneway, analyzes the heat exchange process between airflow and wall rock, and establishes a more reasonable heat exchange model for underground temperature forecast and design and calculation of ventilation cooling in deep mine.Using low-temperature rock stratum to cool the inlet airflow naturally achieves energy saving of mine cooling.On the basis of theoretical model of heat exchange between airflow and wall rock, this paper makes a detailed analysis on geothermal precooling data measured in Jinqingding mine area of Jinzhou Mining Group, and obtains specific varying law of original rock temperature and airflow temperature and relative position of zones of variable temperature, constant temperature and warming temperature, makes an economic analysis of geothermal cooling effect, which provides basic data and conditions for analyzation and validation of the model.Finally, the model is validated utilizing geothermal precooling data measured in Jinqingding mine area of Jinzhou Mining Group and the analysis results of these data, so a comparatively simple and accurate method for calculation of heat and cold exchange between wall rock and airflow is provided. At the same time, as a comparison, the winter condition (geothermal preheating condition) of the precooling system above is calculated and simply analyzed using the research fruit of this paper. The result shows that, the research fruit of this paper are also appropriate for design and calculation of geothermal preheating system.