Simple model and control strategy of earth-to-air heat exchangers

The worldwide energy situation forces industrialized countries to reduce their energy consumption, especially in the building sector, which makes up a high proportion of the total consumption. Techniques such as earth-to-air heat exchangers must therefore be developed and managed to meet this challenge. Yet earth-to-air heat exchangers provide better performance when linked to efficient control strategies. An earth-to-air heat exchanger is modeled using TRNSYS 16 software. The aim of this modeling is to evaluate the efficiency of different control rules, in order to develop an efficient control strategy. The validation of the model yields good results, as the difference between outlet air temperatures predicted by the model and experimental measurements is lower than 2degC for 98.8% of the simulation time and lower than 1degC for 82.9% of this time, with a maximal difference of 2.7degC. The control architecture presented here is then evaluated on the earth-to-air heat exchanger model connected to a single zone building in five different climates. It is shown that this strategy reduces annual energy consumption by 7 to 22%, as a function of climate.