回灌溶液盐度变化对浅层储能咸水介质热量运移特性影响

Influence of Recharge Solution Salinity upon the Thermal Transfer Characteristics in Energy Storage Superficial Brackish Aquifers

根据地下储能咸水层水文地质特性,以多孔介质传热、传质理论为基础,建立咸水层多场耦合储能模型.以天津市某咸水储能系统为研究对象,探索采用不同盐度溶液回灌模式下含水层热量运移特性及温度场变化规律.经模拟计算得到,采用1∶1混合溶液与去离子水回灌时,粗粉砂层在夏季储热期与次年春季间歇期的热作用半径变化率分别为0.313、-0.016,0.348、-0.04m/d.研究表明,在储能阶段,伴随回灌溶液盐度降低,地下水渗流速度上升,导致对流换热与热弥散效应增强,回灌溶液温度场影响范围、幅度增加;间歇阶段,则由于地下咸水与回灌溶液间盐度梯度变大,在分子扩散作用下含水层渗流溶液热作用半径收缩.

Due to the hydrogeologic particularity of brackish aquifers,a three-dimensional couple numerical model of groundwater flow and heat transferring and solute movement in brackish aquifers was established based upon the thermal and mass transferring in porous media. The calibrated numerical model was used to probe into the thermal transfer characteristics and the variation regularity of the geo-temperature field in different modes of recharge solution salinity with the brackish aquifer energy storage system in Tianjin as an example. The simulated calculation indicates that the change rate of the thermal effects radius is 0. 313,-0. 016.0. 348,-0. 04 m / d in the coarse silt aquifer when the 1∶ 1 mixed solution and the deionization solution recharge during the heat storage period of summer and the intermittent recovery period of next spring separately. The results show that the seepage velocity of groundwater increases while the recharge solution salinity decreases during the energy storage stage,which intensifies heat convection and thermodispersion and then increases the influence scope and range of the recharge solution temperature field. During the intermittent stage,the salinity gradient between the original brackish solution and solution recharge becomes larger when the injection salinity decreases and the mechanical dispersion capability becomes stronger,which shrinks the thermal effects radius of the infiltration solution in brackish aquifers.