针对水源热泵回灌中的地面沉降问题,有必要对微生物堵塞现象进行分析研究。采用砂层淤堵装置、玻璃珠和不同孔隙率的砂砾颗粒,分别研究大肠杆菌在多孔介质的浓度沉积特性、突破曲线和渗透系数。试验结果表明：分层位置处大肠杆菌累积显著,在回灌过程中,增加流速可使得堆积的大肠杆菌进入剥离状态,其运移路径数量增加,从而提升回灌效果;在不同流速条件下,大肠杆菌在两种不同介质中呈现出不同的“浓度-时间”关系变化曲线,玻璃珠孔隙的均匀性和表面的光滑性不利于大肠杆菌的沉积,相反,砂砾的内部咬合力有利于大肠杆菌的沉积。通过COMSOL对特征单元体进行数值模拟,对比分析试验现象和过程,发现两者的吻合度较好。在实际应用中,可通过增加流速达到回扬的目的;大肠杆菌在多孔介质中的流动主要分为3个过程：堵塞、迁移、沉积稳定。当渗透系数减小时,末端流出液的大肠杆菌浓度较小,反之较大。研究成果对水源热泵长期稳定运行具有一定现实意义。
Abstract
The study of microbial blockage during the recharge process of ground source heat pumps is of great engineering significance in addressing for solving ground subsidence. The concentration deposition characteristics, breakthrough curve, and permeability coefficient of Escherichia coli in porous media were investigated using a sand layer blockage device. The experimental results show that： （1） the layered position tends to accumulate with Escherichia coli. During reinjection, the accumulated Escherichia coli can be mobilized by increasing the flow rate, thereby increasing the migration path of Escherichia coli, thus improving reinjection efficiency. （2） Under different flow rates, Escherichia coli exhibits different relationships between water pressure and time in two different materials. The uniformity of glass bead pores and smooth surfaces hinder the deposition of Escherichia coli. On the contrary, the internal non-uniformity of gravel facilitates the deposition of Escherichia coli. In practical engineering, increasing the flow rate can help achieve rebound. （3） Escherichia coli generally undergoes three modes of movement in porous media： blockage, migration, and stable accumulation. When the permeability coefficient K decreases, the concentration of Escherichia coli in the end effluent is lower. On the contrary, when the permeability coefficient K increases, the concentration of Escherichia coli in the end effluent is higher. The results have certain practical significance for the long-term stable operation of water source heat pumps.
关键词
水源热泵 /
大肠杆菌 /
沉积特性 /
渗透系数 /
地面沉降
Key words
water source heat pump /
escherichia coli /
sedimentary characteristics /
permeability coefficient /
surface subsidence
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基金
煤炭安全精准开采国家地方联合工程研究中心开放基金资助（EC2024026）
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