Study On Environment Controlling For Mine Refuge Chamber Based On Mine Pressure Ventilation

The global energy demand is growing with the development of economy and the improvement of living standard.In China,coal consumption takes up the dominant position of the energy consumption structure,while about 90%of coal comes from underground mines.According to investigations,in coal mine gas explosion and fire accidents which are easy to cause mass casualties,more than 80%of the victims died of CO poisoning or asphyxiation.Mine refuge chamber(MRC)is regarded as the last barrier to ensure the safety of surviving personnel after mine accidents.However,it is rare to report the successful application of MRC in the thousands of accidents that have occurred in the recent ten years due to the high construction cost of MRC system and the weak safety consciousness of some coal mining enterprises.Thermal and wet environmental control and air quality assurance are the prerequisites for the safety protection function of MRC.But both thermal environment control and air quality assurance for MRC are the key technical problems,because the electrical power in the underground mine may be broken off due to the accident,and electrical equipments used in coal mine must to be explosion-proof.Facing the difficulty of environmental assurance in temperature and air quality for MRC,this paper intends to explore a comprehensive environmental control method without electrical power through MPPV.On the basis of optimizing the air quality assurance system of MRC based on MPPV,the paper has studied the dynamic heat transfer characteristics between rock and air as well as human heat sources in detail.Air temperature prediction models for MRC under different states,i.e.natural convection and ventilation,will be established to judge whether a MRC needs to take additional cooling measures when ventilated by MPPV.In addition,in order to achieve no-electric,efficient and energy-saving environmental control technologies for MRC with high initial rock temperature,a temperature control method cooling the MPPV by ice storage or solid chemical refrigerant is proposed.And on this basis,a compound temperature control method of‘surrounding rock storage cooling-pressure air cooling'is developed for MRC.The specific scientific research work carried out is as follows:(1)Study on the formation mechanism of extreme environment in MRCThrough an experiment of 50 people living in a MRC,the curve of O₂,CO₂ and CO concentration over time in the MRC is obtained,and the metabolic rate and heat metabolism rate of human respiratory process were determined.The analytical calculation method of the concentration of harmful gases in MRC in the absence of purification measures is obtained through theoretical analysis.A heating experiment in a fifty-person MRC by using heat lamps is performed last 20 hours to demonstrate the air temperature increasing process in MRC under natural convection.(2)Air quality assurance of MRC based on MPPVTo improve the barrier efficiency of air curtain systems for MRC,a series of experiments were carried out to investigate the effects of the structural parameters,installation location,and air flow angle on the barrier efficiency for a constant size of the door frame.To optimize the layout of the ventilation system in MRC,a combined experimental and numerical study is conducted to investigate the effects of the number and layout of air inlets and air outlets as well as the per capita air supply rate on the distribution of harmful gas concentration in MRC.To determine reasonable number and layout of purifying devices in an MRC,a experimental study with five different conditions is carried out to analyze the influence of the number and the layout of purifying device in a MRC.The analytical calculation method of air temperature in MRC under natural convection is obtained by theoretical analysis.(3)Dynamic coupled heat transfer characteristics between rock and air as well as human heat sources in MRCA numerical fifty-person MRC model is built and validated by the experimental data.Based on the numerical model,the characteristic of air temperature varies with time,the air temperature distribution in MRC,as well as the effects of thermal physical parameters of surrounding rock on the dynamic coupled heat transfer characteristics between the rock and the air in MRC,are studied in detail through CFD method.In addition,A new analytical method for predicting the air temperature in MRC under natural convection is established according to the numerical result.A comprehensive fifty-person MRC model with wall thickness of 2.5 combing human-body heat sources and ventilation is established and validated against the experimental data.The effects of the main controlling factors,i.e.the thermal conductivity,density and thermal capacity of the rock,the heat generation rate,the ventilation volume rate and the wall area,on the thermal performance of MRC are investigated in detail by CFD method.According to the numerical result,a calculation method for air temperature prediction in MRC under ventilation is proposed.(4)Study on the optimization of temperature control method in MRC based on MPPV.An experimental study was carried out to determine the feasibility of MPPV in MRC can be cooled by solid chemical refrigerants.A numerical analysis study is performed to investigate the thermal performance of MRC under cooled ventilation.According to the numerical result,a calculation method for air temperature prediction in MRC under cooled ventilation is proposed.Compound method of temperature control in high-temperature MRC through cooled surrounding rock and cooled ventilation.Combined with ice storage cooling technology,a compound temperature control method of‘cooled surrounding rock-cooled ventilation'for high-temperature MRC is developed.In this method,the MPPV will be cooled through storage ice that made by using underground power supply and the surrounding rock of MRC will be cooled by the cooled MPPV during normal production,after the accident happened,the temperature in the MRC will be controlled by cooled MPPV and cooled surrounding rock.Through CFD,the cool characteristics of surrounding rock in MRC is analyzed under continuous cooled MPPV,and the characteristics of temperature controlling in MRC during 96 hours under the compound method is investigated.The method of air temperature prediction in MRC is put forward for the compound method.(5)Strategy of air temperature control method for MRC under MPPVThe surrounding rock of MRC is divided into five levels according to temperature.A different temperature control scheme for MRC with different initial temperature of surrounding rock is proposed,and the selection strategy of the temperature control method for MRC is established.