Every year in China,a significant number of mines are closed or abandoned.The pumped hydroelectric storage(PHS)and geothermal utilization are vital means to efficiently repurpose resources in abandoned mine.In this wo...Every year in China,a significant number of mines are closed or abandoned.The pumped hydroelectric storage(PHS)and geothermal utilization are vital means to efficiently repurpose resources in abandoned mine.In this work,the development potentials of the PHS and geothermal utilization systems were evaluated.Considering the geological conditions and meteorological data available of Jiahe abandoned mine,a simple evaluation model for PHS and geothermal utilization was established.The average efficiency of the PHS system exceeds 70%and the regulatable energy of a unit volume is over 1.53 kW·h/m^(3).The PHS system achieves optimal performance when the wind/solar power ratio reaches 0.6 and 0.3 in daily and year scale,respectively.In the geothermal utilization system,the outlet temperature and heat production are significantly affected by the injection flow rate.The heat production performance is more stable at lower rate flow,and the proportion of heat production is higher in the initial stage at greater flow rate.As the operating time increases,the proportion of heat production gradually decreases.The cyclic heat storage status has obvious advantages in heat generation and cooling.Furthermore,the energy-saving and emission reduction benefits of PHS and geothermal utilization systems were calculated.展开更多
This paper studies the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 to 10.0 μm in an office room with three air distribution methods,includ...This paper studies the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 to 10.0 μm in an office room with three air distribution methods,including mixing ventilation（MV）,displacement ventilation（DV）,and under-floor air distribution（UFAD）.The simulation results indicate that exhaled droplets with diameters up to 10.0 μm from normal respiration process are uniformly distributed in MV.However,they become trapped at the breathing height by thermal stratifications in DV and UFAD,resulting in a high droplet concentration and an increased exposure risk to other occupants.Sneezed/coughed droplets are more slowly diluted in DV/UFAD than in MV.Low air speed in the breathing zone in DV/UFAD can lead to prolonged human exposure to droplets in the breathing zone.展开更多
The necessity and feasibility of the use of the personalized ventilation（PV）technology in a toll booth is described.First,the indoor environment of the toll booth equipped with a PV system is analyzed.Based on the a...The necessity and feasibility of the use of the personalized ventilation（PV）technology in a toll booth is described.First,the indoor environment of the toll booth equipped with a PV system is analyzed.Based on the analysis results,a set of equipment for controlling the indoor air quality（IAQ）of the toll booth is devised.Then,a full-scale model of the toll booth is set up in the laboratory.The airflow organization,the optimum operation parameters,and the restraint effects of the PV system on pollution are also experimentally studied.The experimental results on the air supply characteristics show that the PV system can effectively reduce the air age,improve the ventilation efficiency,and enhance the comfort and acceptability of human beings.In addition,this system plays a significant role in preventing pollution.展开更多
基金Project(8212033)supported by the Natural Science Foundation of Beijing,ChinaProject(BBJ2023051)supported by the Fundamental Research Funds of China University of Mining and Technology-BeijingProject(SKLGDUEK202221)supported by the Innovation Fund Research Project,China。
文摘Every year in China,a significant number of mines are closed or abandoned.The pumped hydroelectric storage(PHS)and geothermal utilization are vital means to efficiently repurpose resources in abandoned mine.In this work,the development potentials of the PHS and geothermal utilization systems were evaluated.Considering the geological conditions and meteorological data available of Jiahe abandoned mine,a simple evaluation model for PHS and geothermal utilization was established.The average efficiency of the PHS system exceeds 70%and the regulatable energy of a unit volume is over 1.53 kW·h/m^(3).The PHS system achieves optimal performance when the wind/solar power ratio reaches 0.6 and 0.3 in daily and year scale,respectively.In the geothermal utilization system,the outlet temperature and heat production are significantly affected by the injection flow rate.The heat production performance is more stable at lower rate flow,and the proportion of heat production is higher in the initial stage at greater flow rate.As the operating time increases,the proportion of heat production gradually decreases.The cyclic heat storage status has obvious advantages in heat generation and cooling.Furthermore,the energy-saving and emission reduction benefits of PHS and geothermal utilization systems were calculated.
基金The National Natural Science Foundation of China(No.50808133)the Dean's Reserve of Faculty of Construction and Land Use at the Hong Kong Polytechnic University
文摘This paper studies the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 to 10.0 μm in an office room with three air distribution methods,including mixing ventilation（MV）,displacement ventilation（DV）,and under-floor air distribution（UFAD）.The simulation results indicate that exhaled droplets with diameters up to 10.0 μm from normal respiration process are uniformly distributed in MV.However,they become trapped at the breathing height by thermal stratifications in DV and UFAD,resulting in a high droplet concentration and an increased exposure risk to other occupants.Sneezed/coughed droplets are more slowly diluted in DV/UFAD than in MV.Low air speed in the breathing zone in DV/UFAD can lead to prolonged human exposure to droplets in the breathing zone.
文摘The necessity and feasibility of the use of the personalized ventilation（PV）technology in a toll booth is described.First,the indoor environment of the toll booth equipped with a PV system is analyzed.Based on the analysis results,a set of equipment for controlling the indoor air quality（IAQ）of the toll booth is devised.Then,a full-scale model of the toll booth is set up in the laboratory.The airflow organization,the optimum operation parameters,and the restraint effects of the PV system on pollution are also experimentally studied.The experimental results on the air supply characteristics show that the PV system can effectively reduce the air age,improve the ventilation efficiency,and enhance the comfort and acceptability of human beings.In addition,this system plays a significant role in preventing pollution.
