A Passive Decarbonisation Approach for Hot-Arid Residential Structures: CFD Study of a Courtyard Earth-Air Heat Exchanger in Baghdad Assisted by Thermal Thrust

Abstract

One of the biggest contributors to the world's energy consumption and carbon emissions is the building industry, especially in hot and dry countries where the yearly building energy use is dominated by the need for cooling. Passive cooling techniques that can lessen reliance on traditional air conditioning systems are desperately needed in Iraq due to the country's severe summer heat and ongoing electricity problems. The effectiveness of a thermal thrust-assisted courtyard earth-air heat exchanger (EAHE) as a passive cooling option for residential structures in Baghdad is examined in this study. Using ANSYS Fluent, a three-dimensional computational fluid dynamics (CFD) model was created to simulate heat transfer and airflow in an underground pipe system under typical local soil and climate conditions. The impacts of pipe diameter (0.2–0.4 m), pipe length (30–80 m), pipe burial depth (1–5 m), and inlet air velocity (1–5 m/s) were methodically assessed. According to simulation results, an ideal balance between thermal performance and pressure losses is achieved with a burial depth of roughly 3 m, pipe length of 60 m, and pipe diameter of 0.25 m. At an intake velocity of 1 m/s, the suggested system was able to reduce the air temperature by up to 20.75 °C during the hottest summer months. Passive airflow and cooling performance are greatly improved when thermal buoyancy (stack effect) is integrated with a courtyard-based EAHE. The findings show that the suggested solution can help hot, dry residential buildings lower their cooling energy consumption and related carbon emissions. These results show how low-carbon building design in Iraq and other climates can be supported by combining contemporary passive cooling technologies with traditional courtyard architecture.