Evaluation of development potential of pumped hydroelectric storage and geothermal utilization system in abandoned coal mine

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.

浸水次数对煤样裂隙发育损伤的实验研究

由于地下水对隔水煤柱和地下水库边界的反复浸水损伤,研究反复浸水对煤样的裂隙损伤作用有助于解决中国西部干旱区半干旱区矿区井下储水以及含水层煤柱留设问题。通过自制浸水装置制取干燥,浸水1次,2次,3次,4次的煤样共5组,分别进行单轴压缩声发射实验。研究表明,煤样的峰值应力、弹性模量随着煤样浸水次数的增加而呈现不同程度的减小,但峰值应变随着浸水次数的增加而变大。刚度应力曲线结合声发射累计计数曲线能阐明裂隙发育的各个阶段,随着反复浸水次数增加,煤样裂隙的闭合应力阈值,裂隙初始发育阈值和裂隙损伤阈值均线性减小,但3个阈值占峰值强度的比值不随着浸水次数改变而变化,其比值分别为15.52%,31.04%和67.81%。实验结果对矿区地下水库建立和隔水煤岩体留设以及探究煤样裂隙发育规律具有指导意义。