A performance of a heat pump system connected a new conic helicoidal geothermal heat exchanger for a greenhouse heating in the north of Tunisia

•Renewable energy sources exploitation by GSHP in a greenhouse is investigated.•A conic geothermal helicoidal heat exchanger under Tunisia climate is investigated.•Experimental study of new heat exchanger (CHGHE) is presented.•The ground source heat pump is evaluated for greenhouse heating.•Effect of various such as, flow rate, position and temperature are tested. The aim of this experimental study is made to examine the performance of a new conic helicoidal geothermal heat exchanger (CHGHE) for greenhouse heating. The main advantage of this geometry of heat exchangers type is to reduce the used area and the operating cost compared to horizontal and vertical, respectively. An experimental study is composed of CHGHE implanted in 3 m depth connected to a geothermal heat pump which is connected to a ceiling panel installed into a greenhouse. This ceiling unit is constituted of an exchangers suspended in internal air and others placed on the ground. This conditioning system allowed a recover the energy in excess into the greenhouse during the day by the exchangers placed on the ground, or, this energy stored is brought back to heat the air in the greenhouse by the suspended exchangers during the night. The experimental results showed that the recovered heat rate from the ground by the CHGHE is about 4.7 kW. However, they are between 12 kW and 10 kW in into greenhouse. The coefficient of the performance of the heat pump (COPhp) and the overall system (COPsys) were found to be 3.93 and 2.64 respectively. The geothermal system insure a quantity of heat equal to 692.208 kW witch correspond to a temperature increasing of 3 °C under greenhouse for an optimal water flow rate of 0.6 kg/s.