Parametric Dependence and Performance Assessment of Ground Coupled Heat Exchangers

The energy usage of the heating, ventilation, and air conditioning systems is increasing with the increase in living standards in recent years, as these systems are consuming more than one-third of the total energy usage. Conventional air conditioning systems are energy expensive and also lead to global warming. Passive air conditioning systems using renewable energy methods are appreciated for achieving thermal comfort in building premises. Ground coupled heat exchanger system is a passive technology that can be used for lowering the cooling as well as the heating load of the buildings. This system exploits the thermal potential of the ground subsoil for attaining desired thermal comfort conditions. The aim of the present work is to review various analytical, simulation, and experimental studies that have been performed in the last few years to examine the different design and operating parameters for enhancement of the thermal performance of ground-coupled heat exchangers. The authors critically reviewed the effect of thermo-hydraulic parameters of the working fluid, pipe material and geometrical properties, and soil thermo-physical parameters on thermal performance. From a thorough review of considered articles, it is concluded that the integration of ground-coupled heat exchangers with promising design guidelines will be able to provide a promising answer for improving the building energy efficiency and achieving sustainable buildings with either net zero or nearly zero energy consumption. Finally, some recent studies are also briefly discussed that consider incorporating phase change materials to further improve the thermal performance and adaptation of ground-coupled heat exchanger system.