Contribution of the Provençal Well for the Improvement of the Thermal Comfort in the Building in Turbulent Regime

Abstract

In the current energy context, geothermal systems are highly developed in the building field. Among these interesting systems on the energy plan, one finds in particular the earth-to-air heat  exchanger commonly called ‘Canadian or Provençal well’. It consists of tubes buried in which the ambient air is pushed in order to be refreshed in contact with the ground whose temperature is quasi-constant throughout the year. In this work, a study of the performance of an earth-to-air heat exchanger was undertaken by means of numerical modeling of heat exchange by forced convection in a buried tube. The transfer equations in the tube are discretized using the finite volume method in turbulent regime and solved using the Thomas algorithm. For the determination of the ground temperature, the model of the semi-infinite mass subjected to a periodic excitation was adopted. The soil temperature was used as a boundary condition for the buried tube. The results show that the interest of the earth-to-air heat exchanger is major, since it improves throughout the year, the thermal conditions sought. It intervenes in an effective way on the damping of the thermal amplitudes in the building. The variation of the diameter and the length of earth-to-air heat exchanger does not influence notably the distribution of the streamlines and isotherms but affect significantly the values of stream function and temperature inside de tube of the earth-to-air heat exchanger. When diameter of the pipe increases, the outlet temperature increases. The increase of the length of the earth-to-air heat exchanger leads to the isotherms increase as a result of the intensification of heat exchange between the walls and the convective jet. The temperature in the air outlet compartment is lower as the length of the earth-to-air exchanger increases.