Numerical Analysis and Evaluation of Large-Scale Hot Water Tanks and Pits in District Heating Systems

A key lever to overcome the challenges in buildings sector related to today's extensive utilization of fossils (e.g. global warming) is to integrate renewables (e.g. solar energy) into district heating systems. However, solar energy fluctuates based on seasonal and hourly patterns. This pinpoints the significance of seasonal thermal energy storage (STES) systems. This work investigates the numerical modeling of two STES (tank and pit). Since the groundwater existence can reduce the STES performance and, on the other hand, the STES has an influence on the groundwater, the paper examines the performance of an underground tank with existence of groundwater.