Earth-air heat exchangers can be used to reduce energy consumption in building ventilationsystems. The idea is to pre-heat air in winter and pre-cool air in summer using the thermalcapacity of the soil. To do this concrete and plastic tubes are put underground, through whichthe ventilation air is drawn.In this paper a 3D unstructured finite volume model is derived, which allows evaluating theearth-air heat exchanger. The model solves conduction through the soil and the convectionfrom air to the tube wall. The air ground-surface heat transfer is described by the heat fluxthrough convection and solar radiation.The model is used to study the performance of the earth-air heat exchanger in the Belgianclimate.It is shown that in summer the air can be cooled with about 9 °C at sufficient depth (3m) andtubes of about 50 m. In winter heating of 7 °C can be realised. It is also shown that a goodcontrol strategy is important.
展开▼
