COMPARING AN ANALYTICAL AND A NUMERICAL MODEL FOR EARTH-AIR HEAT EXCHANGERS IN THE BRAZILIAN SOUTH REGION

Resumo

The Earth-Air Heat Exchangers (EAHE) represent a promising option to reduce the
heating/cooling load of buildings. Unlike traditional air conditioning systems, the EAHE employ a
renewable source of energy and they can operate using little electric power. Basically, EAHE use
buried ducts, where the air is blown by fans to exchange heat with the soil. Since the first layers of the
ground are warmer than the outside air in the winter, and colder in the summer, the Earth can be used
as heat source or sink. Therefore, the air leaves the ducts at milder temperatures. Recent research has
shown that these devices can work properly in the south region of Brazil, where prevails a subtropical
climate. This work aims to compare an analytical model with a numerical one, analyzing their results
with experimental data from an EAHE installation in the city of Viamão, located in the Brazilian state
of Rio Grande do Sul. As it is shown ahead, the analytical model is not only more simple, but also
more accurate than the numerical model.