Ground source heat pump systems in Central Asia: A case study from Dushanbe, Tajikistan

• A GSHP system was modeled in Dushanbe city for the first time. • The model was validated using a double validation method. • The accuracy was confirmed using the GHE's outlet temperature. • The ground temperature profile was validated using an optic fiber sensor. • Only a 1.3 °C increase in the GHE's outlet temperature was observed after 10 years of operation. • The average heating and cooling COPs were calculated as 7.20 and 9.95, respectively. This study evaluated the applicability of a ground source heat pump GSHP system for heating and cooling applications in Dushanbe City, Tajikistan, by modeling an existing project in the city for the first time. Given the region's limited energy resources and heavy reliance on hydropower, the GSHP system presents a promising solution for sustainable heating and cooling demands in a country with a heating-dominated climate. The research employs numerical simulations validated with actual recorded data in the field, and providing a comprehensive analysis of both short-term and long-term performance calculating the heating and cooling Coefficient of Performance (COP) in the winter and summer, respectively. The model developed in FEFLOW software was validated perfectly using the TRT data including outlet temperature of the GHE and as well as ground temperature profiles recorded by an optical fiber sensor inserted into the GHE's return pipe from the beginning of the test until 48 h after test completion. The long-term simulation showed that the minimum ground temperature was only decrease about 1.3 °C during the 10-years of operation with the COP decrement of about 0.28, which was fairly acceptable performance. Results highlight the potential of GSHP systems to enhance energy efficiency and reliability in this country and as well as Central Asia. This pioneering study demonstrates the viability of GSHP technology in Tajikistan, offering valuable insights for future energy planning and sustainable development in the region. TRT machine and optical fiber sensor installation method in the return pipe of the GHE