Evaluation of ground source heat pump system’s enhancement by extracting groundwater and making artificial groundwater velocity
Evaluation of ground source heat pump system’s enhancement by extracting groundwater and making artificial groundwater velocity
复制标题
DOI：
10.1016/j.enconman.2020.113298
复制
发表时间：
2020-11
影响因子：
10.4
通讯作者：
Saeid Mohammadzadeh Bina;Hikari Fujii;H. Kosukegawa;Hadi Farabi-Asl
中科院分区：
文献类型：
--
作者：
Saeid Mohammadzadeh Bina;Hikari Fujii;H. Kosukegawa;Hadi Farabi-Asl
本研究使用移动线源技术作为一种实用的方法，同时确定有效导热系数、地下水流速和井筒阻力。它主要集中在这种方法在观察地下水开采效果方面的适用性，特别是对于无灌浆的地下热交换器。在日本北部秋田大学校园的两个地点对不同的地下换热器进行了热响应测试。测试条件根据不同的钻孔充填条件(灌浆/非灌浆)、热负荷和是否有额外的地下水抽取泵而有所不同。地面水热参数的确定采用了MatLab程序，特别是在一种特殊的测试条件下，考虑了人工地下水流速的影响，在测试过程中用水泵从井筒中抽取地下水。该方法通过再现井筒内的温度分布和最小化计算值与实测值之间的均方根误差，来估算地下水流速度和土壤有效导热系数。结果表明，由于有外泵的存在，地下水流速和导热系数分别提高到205.3 cm/d和7.48W/mK，而未加泵的地下水流速估计在15~16 cm/d之间。此外，据报道，灌浆井的最小地下水流速和导热系数分别为10.79亿厘米/天和1.16亿瓦/米·K。
This study used moving line source technique as a practical approach to simultaneously determine effective thermal conductivity, groundwater velocity and borehole resistance. It mainly focused on the applicability of this approach for observing the effect of groundwater extraction, in particular for ungrouted ground heat exchangers. The thermal response tests were carried out for different ground heat exchangers at two sites on the Akita University campus, northern Japan. The test conditions varied, based on different borehole filling condition (grouted/ungrouted), heat loads and presence of an extra pump for groundwater extraction. The hydro-thermal parameters of the ground were determined by a MATLAB code, especially for consideration of the effect of artificial groundwater velocity under a special test, where a water pump extracts the groundwater from the casing of the borehole during the test. This method can estimate the groundwater velocity and the effective thermal conductivity of the soil by reproducing the temperature distribution in the well and minimizing the root mean squared error between the calculated results and the measured data. As a result, the groundwater velocity and thermal conductivity calculated by this method improved to 205.3 cm/day and 7.48 W/m K, respectively, due to presence of the external pump, whereas the undisturbed groundwater velocity in the other cases without pumping was estimated in the range of 15 to 16 cm/day. Furthermore, the minimum groundwater velocity and thermal conductivity were reported for the grouted well as being equal to 10.79 cm/day and 1.16 W/m K, respectively.