Thermal performance of a conic basket heat exchanger coupled to a geothermal heat pump for greenhouse cooling under Tunisian climate

• We study a conic geothermal basket heat exchanger (CGBHE) under Tunisia climate.
• The CGBHE is coupled to a geothermal heat pump and evaluated for greenhouse cooling.
• A comparison between analytical and experimental results is performed.

This paper presents an experimental analysis to examine the performance of a new conic basket geothermal heat exchanger (CBGHE) for greenhouse cooling. This system has never been used or exploited in Tunisia for any research or industrial purposes. Therefore, an experimental system was designed, installed and tested in the Research and Technology Center of Energy (CRTEn) of Borj Cedria.The configuration typically consists of a series of parallel coil implanted in 3 meter depth. The experiments are conducted between 7th and 8th June 2014. The results obtained show that the CBGHE system can be used in the Mediterranean regions such as Tunisia for greenhouses cooling. During the experimental period the maximum quantity of heat transferred to the ground by the CBGHE is about 8 kW. The maximum average temperature difference between the inlet and outlet CBGHE system is approximately 30 °C, with measured mass flow rate of 0.08 kg/s. The air temperature inside the greenhouse decreased of about 12 °C.After the stabilization of the CBGHE system, the performances coefficients of the geothermal heat pump (COPhp) and the overall system (COPsys) are 3.9 and 2.82, respectively.