Experimental study of ground source heat pump system coupled with a new auxiliary heat source for space heating: A case study of Tunisia

This paper investigates the potential of geothermal energy in Tunisia, firstly by assessing geothermal resources and exploitations, and secondly by evaluating the energy performance and economic benefits of a ground source heat pump (GSHP) coupled with an underground buried tank (UBT) to address high building energy consumption. An experimental ground heat exchanger coupled with a geothermal heat pump and an underground buried tank was constructed and evaluated at the Research and Technology Center of Energy in Borj Cédria, northern Tunisia. The GSHP system's performance was analyzed experimentally during space heating operation. The results show that geothermal energy is a promising solution for reducing heating energy consumption in Tunisia. Specifically, the ground heat exchanger and the underground buried tank extract 5 and 2.5 kW of energy, respectively once the compressor is activated and the system is stabilized. The coefficients of performance, COP_hp and COP_sys, were approximately 4.53 and 3.02, respectively, proving the efficiency of the system. The economic study shows that the GSHP system saves approximately 46 % and 55 % of operating costs over a 20-year lifecycle compared to the air conditioner and the CHS, respectively.