Modelling and evaluation of cooling capacity of earth-air-pipe systems

Earth-air-pipe systems can be used to reduce the cooling load of buildings in summer. A transient and implicit model based on numerical heat transfer and computational fluid dynamics was developed to predict the thermal performance and cooling capacity of earth-air-pipe systems. Superposition technology is used in the model, incorporating the natural ground temperature field and the turbulent air flow inside the buried pipe. The model developed is validated against experimental investigations on an experimental set-up in Southern China. Good agreement between simulated results and experimental data is obtained. The model is then implemented on the CFD (Computational Fluid Dynamics platform), PHOENICS, to evaluate the effects of the operating parameters (i.e. the pipe length, radius, depth and air flow rate) on the thermal performance and cooling capacity of earth-air-pipe systems. A daily cooling capacity up to 74.6 kW h can be obtained from an earth-air-pipe system installed in that region.