地下水源热泵系统热平衡模拟三维数值模型

Three-dimensional numerical model for heat balance simulation of ground-water heat pump

为了准确模拟预测地下水源热泵系统运行期间的热平衡变化规律特征,避免未来地下水源热泵系统运行期间出现的热贯通现象。以河北省水勘院正定基地地下水源热泵系统示范工程为例,建立了地下水渗流与热量运移三维耦合数值模型,并结合地下水源热泵系统的设计运行方案,预测分析了不同条件下未来地下水源热泵系统的热平衡发展趋势。结果表明,该示范工程按设计方案运行,抽、灌井之间存在热贯通现象。地下水源热泵系统通过增大温差的方法进行调节,可有效地缓解热贯通现象。

In order to simulate and predict the change law of heat balance accurately and avoid heat penetration phenomenon during the groundwater heat pump operation, a three dimensional coupling numerical model of groundwater seepage and thermal transport was established and applied to the demonstration project of groundwater heat pump system in Zhengding, Hebei province. The model was based on the groundwater seepage theory, saturated water-bearing medium thermal transport theory and Terzaghi effective stress principle, combined with the design scheme and operation situation of groundwater heat pump, the future heat balance development tendency of groundwater heat pump system under three different conditions was forecasted and analyzed. The water temperature difference between the pumping well and recharge well reduced by 20% （eight degree centigrade） or increased by 20% （twelve degree centigrade） was the first condition which means the cooling and heating load was kept constant. Second condition was the water temperature difference between pumping well and recharge well confirmed and the circulating water volume increased by 20%, or the volume of circulating water kept constant and water temperature difference between pumping well and recharge well increased 20%, which means the cooling and heating load was increased. Meanwhile, in the third condition, the cooling and heating load was reduced. The water temperature difference between the pumping well and recharge well was confirmed and the volume of circulating water reduced 20%, or the water temperature difference between pumping well and recharge well reduced 20% while the circulating water volume kept constant. It was shown that there is a heat penetration phenomenon between the pumping well and recharge well in the demonstration project under the condition of design scheme, which has one pumping well and one recharge well. When the cooling and heating load of the groundwater heat pump system is confirmed, increasing 20% of the water temperature difference between the pumping well and recharge well is more conducive to remiting the heat penetration between the pumping well and recharge well than reducing 20% of the water temperature difference between pumping well and recharge well. In addition, when the cooling and heating load of the groundwater heat pump system is increased, increasing 20% of the water temperature difference between the pumping well and recharge well is a more efficient method for remiting the heat penetration between pumping well and recharge well than reducing 20% of the circulating water volume. Meanwhile, when the cooling and heating load of the groundwater heat pump system is reduced, reducing 20% of the circulating water volume is more conducive to remiting the heat penetration between pumping well and recharge well than reducing 20% of water temperature difference between the pumping well and recharge well. This research indicates in the groundwater heat pumping system, reducing circulating water volume and increasing water temperature difference between pumping well and recharge well can remit heat penetration phenomenon effectively.