Numerical Modelling of Thermo-active Micropiles

Energy piles (EPs), consisting in piled foundations equipped with heat exchangers, have been extensively studied in recent years, both from the thermo-mechanical response and energy performance points of view. However, most research refers to typical rotary bored, CFA or precast driven, medium diameter piles. Not much attention has been devoted to so-called energy micropiles (EMPs), representing an opportunity to provide at the same time energy and structural retrofitting to existing buildings. Existing studies show that EMPs overall may thermally perform differently to EPs, but they are comparable in terms of specific heat flux. In this work, a 3D FE numerical model is employed to perform a comprehensive parametric study considering design factors that are peculiar to EMPs, to assess the most important parameters to maximize their energy performance. The parameter space is efficiently explored resorting to a statistically-based Taguchi approach. Results show that thermal design of EMPs should not be based on the same criteria as those used for medium-large diameter EPs, since different parameters are dominant in enhancing their energy performance. In particular, the pipes diameter should be maximized in EMPs for its strong influence in results, while being very easy to engineer.