Wildemeersch S, Jamin P, Orban P, Hermans T, Klepikova M, Nguyen F, Brouyère S, Dassargues A
University of Liege, ArGEnCo, GEO(3), Hydrogeology and Environmental Geology, Aquapôle, B52/3 Sart-Tilman, 4000 Liege, Belgium.
University of Liege, ArGEnCo, GEO(3), Hydrogeology and Environmental Geology, Aquapôle, B52/3 Sart-Tilman, 4000 Liege, Belgium.
J Contam Hydrol. 2014 Nov 15;169:90-99. doi: 10.1016/j.jconhyd.2014.08.001. Epub 2014 Aug 12.
Geothermal energy systems, closed or open, are increasingly considered for heating and/or cooling buildings. The efficiency of such systems depends on the thermal properties of the subsurface. Therefore, feasibility and impact studies performed prior to their installation should include a field characterization of thermal properties and a heat transfer model using parameter values measured in situ. However, there is a lack of in situ experiments and methodology for performing such a field characterization, especially for open systems. This study presents an in situ experiment designed for estimating heat transfer parameters in shallow alluvial aquifers with focus on the specific heat capacity. This experiment consists in simultaneously injecting hot water and a chemical tracer into the aquifer and monitoring the evolution of groundwater temperature and concentration in the recovery well (and possibly in other piezometers located down gradient). Temperature and concentrations are then used for estimating the specific heat capacity. The first method for estimating this parameter is based on a modeling in series of the chemical tracer and temperature breakthrough curves at the recovery well. The second method is based on an energy balance. The values of specific heat capacity estimated for both methods (2.30 and 2.54MJ/m(3)/K) for the experimental site in the alluvial aquifer of the Meuse River (Belgium) are almost identical and consistent with values found in the literature. Temperature breakthrough curves in other piezometers are not required for estimating the specific heat capacity. However, they highlight that heat transfer in the alluvial aquifer of the Meuse River is complex and contrasted with different dominant process depending on the depth leading to significant vertical heat exchange between upper and lower part of the aquifer. Furthermore, these temperature breakthrough curves could be included in the calibration of a complex heat transfer model for estimating the entire set of heat transfer parameters and their spatial distribution by inverse modeling.
无论是封闭式还是开放式的地热能系统，越来越多地被考虑用于建筑物的供热和/或制冷。此类系统的效率取决于地下的热特性。因此，在安装之前进行的可行性和影响研究应包括热特性的现场表征以及使用现场测量参数值的传热模型。然而，缺乏进行这种现场表征的原位实验和方法，特别是对于开放式系统。本研究提出了一种原位实验，旨在估算浅层冲积含水层中的传热参数，重点是比热容。该实验包括同时向含水层注入热水和化学示踪剂，并监测回灌井（以及可能在下游的其他测压管）中地下水温及浓度的变化。然后利用温度和浓度来估算比热容。估算该参数的第一种方法基于对回灌井处化学示踪剂和温度突破曲线的串联建模。第二种方法基于能量平衡。在比利时默兹河冲积含水层的实验场地，两种方法估算出的比热容值（2.30和2.54MJ/m³/K）几乎相同，且与文献中的值一致。估算比热容不需要其他测压管中的温度突破曲线。然而，它们表明默兹河冲积含水层中的传热很复杂，不同深度的主导过程不同，导致含水层上下部分之间存在显著的垂直热交换。此外，这些温度突破曲线可纳入复杂传热模型的校准中，通过反演建模估算整套传热参数及其空间分布。
