| At present,the average mining depth of coal mines in China is more than 700m,and the coal reserves under the burial depth of more than 1000m account for more than half of the total resources in China.Deep mining has become the top priority,but deep engineering is faced with different degrees of thermal environment problems.Thermal damage caused by deep high temperature environment leads to mining difficulties,and the health and working ability of the workers are greatly affected.Therefore,it is necessary to implement cooling of the mine.Traditional mine cooling has problems such as high energy consumption in operation and large system design capacity.The use of mine roadway insulation layer has been the focus of domestic researchers.Although wall insulation can reduce the heat dissipation of surrounding rock,it is still difficult to improve the working environment of the mine and make it meet the requirements of thermal comfort.This article from the geopolymer phase change materials and thermal insulation layer coupling temperature control perspective,the preparation of the polymer phase change materials,the thermal physical parameters and the different environmental conditions influence on wind temperature,phase change layer through thermal comfort index and subjective evaluation questionnaire research miner thermal comfort,and use the artificial environment chamber insulating polymer phase change materials by human body thermal comfort difference before and after cooling.The main conclusions of the study are as follows:First of all,on the basis of the research team,geopolymer phase change materials were prepared by adding phase change microcapsules into geopolymer foams.The influence of foam content and polypropylene fiber content on the mechanical properties and thermal conductivity of the material was studied by the control variable method.With the increase of foam content,the compressive strength first increased and then decreased,and the thermal conductivity coefficient showed the same trend as the compressive strength.The relationship between the content of polypropylene fiber and the compressive strength is approximately linear,and the thermal conductivity increases slightly with the increase of fiber content.The influences of foam content,phase change microcapsule content and fiber content on the compressive strength and thermal conductivity of materials were analyzed by orthogonal test method.The results show that the foam content is the most important factor affecting the test indexes,while the fiber content and phase change microcapsule content have little influence.A group of optimal indexes were selected by efficiency coefficient method.The compressive strength was 22.82MPa and the thermal conductivity was 0.431 W/(m·K),which could be used as shotcrete support materials.Then,combined with the geopolymer phase change materials of the preparation of the second chapter,numerical simulation method was used to study the variation of air flow temperature in deep underground tunnel with phase change materials,the effects of thermal parameters and environmental conditions on air flow temperature of phase change layer were analyzed,including the phase change temperature and phase change latent heat,thermal conductivity,phase transition temperature range,phase change layer thickness and air speed.The results show that the temperature of the inner wall is effectively controlled by the phase transition temperature during the temperature control time.The higher the latent heat is,the stronger the temperature control ability is,but the utilization efficiency is low.The temperature range and thermal conductivity have little effect on the inner wall temperature of the phase change layer.The greater the thickness of the phase change layer is,the more obvious the insulation effect is,and the lower the temperature of the inner wall of the phase change layer is.The greater the air supply velocity is,the more obvious the periodicity of heat flow and temperature on the inner wall of phase change layer is.When the phase transition temperature is 18?,the latent heat of phase change is 6k J/kg and the thickness of phase change layer is0.1m,the heat dissipation of surrounding rock to airflow is reduced to 18%,6%and4%,respectively,compared with the tunnel structure.The thermal conductivity and phase transition temperature range have little influence on the heat dissipation of surrounding rock.The greater the inlet wind speed is,the heat dissipation of surrounding rock will be taken away and the heat insulation effect will be affected.The lower the inner wall temperature,the higher the latent heat of phase change and the higher the thickness of phase change layer,the better the heat insulation effect,which is the most effective way to reduce the heat dissipation of surrounding rock.Finally,the thermal environmental parameters of a coal mine with typical heat damage were measured.The dry ball temperature and relative humidity gradually increased and the wind speed gradually decreased along the 8433 working face of fully mechanized mining.The metabolic rate analysis of 110 miners showed a normal distribution,and 81%of the miners were above the high metabolic rate.PMV_e-PPD and WBGT index were compared and analyzed for the working face environment.WBGT index was better in evaluating the thermal stress of human mine environment under thermal load,while PMV_e-PPD was too high in evaluating the thermal comfort of underground personnel.Do the questionnaire of miners in the summer,noisy,light is weak,feeling partial hot,humid feeling strong,blowing feeling weak,are factors that influence the miner thermal comfort is poor thermal comfort and air temperature,there was no significant correlation between freshness and crowded degree,negatively related with humidity,noise,and wind speed and light were positively correlated relationship,Thermal comfort increases as humidity decreases,wind speed increases,noise decreases and light increases.By using PHS model to analyze the influence of different working conditions on the thermal physiological state of personnel,it is found that the thermal radiation temperature,relative humidity,air temperature,wind speed and metabolic rate have a significant influence on the thermal physiological state of personnel.The higher the thermal radiation temperature,the higher the relative humidity,the higher the air temperature,the lower the wind speed,and the higher the metabolic rate,the greater the acceptable maximum exposure time.An artificial environment chamber was used to simulate the real environment of the mine.Subsubjective questionnaire survey and physiological parameter changes were used to analyze the changes of human thermal comfort before and after cooling in the phase change layer.Before cooling,TSV,TCV and TEAV gradually increased with the increase of temperature.After cooling down,the human body tends to be satisfied with the thermal environment,the core temperature rises at a lower rate,and the thermal comfort increases.There are 81 pictures,32 tables and 109 references in this paper. |
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