Assessing the Thermal Efficiency of Horizontal Air-Ground Heat Exchangers for Heating and Cooling Buildings in the Northwestern Algeria Region

Abstract

The earth-air heat exchanger is a geothermal system that exploits the thermal inertia of the ground. It is a promising environmentally friendly technique that can effectively reduce or cancel out heating and cooling loads in the building sector. This study presents a numerical simulation of horizontal ground-air heat exchange system to investigate the effectiveness of the ground in heating and cooling buildings. Given the climate of the region located in northwestern Algeria, the investigated system heats the air in winter and cools it in summer. A three-dimensional transient numerical model based on the finite element method is established using COMSOL Multiphysics software. The model takes into account the interaction between the ground and the atmosphere as a boundary condition at the ground surface, and all climatic and geological conditions of the region are considered. Next, the model evaluates the coupling of heat and moisture transfer for unsaturated soil. Finally, the interaction between the soil and the ground-air heat exchanger is examined to assess the energy performance of the shallow geothermal system in the study area. The results show that the air temperature drops by 4°C in cooling mode and rises by 2.5°C in heating mode. The heat exchange rate of the horizontal geothermal air heat exchanger system with the environment in cooling mode surpasses that in heating mode by 28%, yielding a performance coefficient of 5.9. These results offer valuable insights into optimizing the performance of geothermal systems for building climate control in Algeria's northwestern region.