Influence of different pumping and recharging schemes on regional groundwater drawdown in groundwater heat pump project: A case in Anhui Fuyang People’s Hospital

Abstract

In the process of exploiting geothermal energy by groundwater heat pump (GWHP), the dynamic equilibrium of regional groundwater drawdown is the basis for sustained operation of GWHP. In this paper, taking the GWHP project of Fuyang People's Hospital in Anhui, China as an example, a mathematical model is established and numerical simulation is carried out based on the hydrogeological conceptual model by using Modflow software. In addition, considering the pattern of same direction recharge, the intersect recharge and the ratio of 90% and 100% reinjection respectively, the area change of the drawdown funnel caused by the GWHP project and the recovery of the water level after the system stopped operation are analyzed. The results show that the funnel area of the pumping well under the 90% recharge ratio is greater than that of the 100% recharge, while the operation result of recharge well is opposite in the most adverse situation of the system with a production volume of 1440m3/d and continuous operation for 4 months. Furthermore, with the same reinjection ratio, the funnel area of the same direction recharge mode is larger than that of the intersect recharge mode in both pumping wells and recharge wells, and increases with the decrease of drawdown. Moreover, with the increase of recharge amount, while the water level of recharge well rises, there is a certain supplement and balance to the water quantity of the pumping well.

Experimental study on the water–rock interaction mechanism in a groundwater heat pump reinjection process

“…In particular, geothermal energy has attracted more and more attention due to its abundant reserves, stable reliability and low carbon dioxide emissions (Ni et al 2015;Xu et al 2016;Wang et al 2017). Groundwater heat pump (GWHP), which is a shallow low-grade geothermal energy technology that uses heat pump units to exchange heat between groundwater and the ground space for the heating or cooling of buildings, as well as for valuable water/waste treatment applications, such as groundwater desalination, has been widely developed and applied in many countries (Luo et al 2016;Makasis et al 2018;Panagopoulos 2021;Yang et al 2021). However, during the long pumping and recharge operations of GWHP, physical, chemical and biological blockage occur in the recharge wells and surrounding aquifers (Hepbasli et al 2014;Athresh et al 2016;Fetzer et al 2017), resulting in a sharp decline in the efficiency of the heat pump system, which has become a key problem that affects the project operation.…”