Performance evaluation of different types of ground source heat exchangers in a hot and dry climate

Most of the energy consumption in a hot and dry area is used for the air-conditioning systems. This study aims to investigate the possibility of reducing the electricity consumption in air conditioners using ground cold energy to cool the hot fluid in the pipes. Several experiments were carried out to investigate the performance of the proposed system to be used in the weather conditions of Baghdad city (i.e., hot and dry). Two configurations of ground source heat exchangers (GSHEs) were developed and constructed. The first configuration comprised coil type with two different materials (copper and polyvinyl chloride [PVC]). The second configuration was the 3U type, which was made from copper, PVC, and galvanized. Three water flow rates were considered (5, 10, and 15 L/min) with water inlet temperatures (80 degrees C, 70 degrees C, and 60 degrees C). The experiments' results showed that the type of material of the pipe has a significant influence on both the heat transfer effectiveness and the system performance. Copper tubes were the best type of heat exchanger (type coil) to be used in this regard. The highest recorded values of the heat exchange rate were 5.81, 4.81, 2.72, 1.60, and 1.32 kW with an inlet temperature of 80 degrees C and a flow rate of 5 L/min for the case of copper coil, copper 3U, galvanized 3U, PVC profile, and PVC 3U, respectively. These findings can be used as a guideline for future studies of GSHEs, particularly for the applications fixed in unsaturated soils.