Numerical and experimental study on a concrete slab behavior in steady periodic state in presence of metal cylinders perpendicular to the slab surface

The well established interest in underfloor heating systems has grown in recent years mainly due to the possibility that these systems offer to be supplied with water at low temperatures, therefore with renewable sources or similar to them (solar energy, heat pump, cogeneration). This advantage and these systems performance can be improved by increasing the thermal conductivity of everything inserted between the pipes in which hot water flows and the indoor environment/ambient. In a previous work a mortar slab with embedded metal cylinders has been studied, to evaluate the conductivity increase due to the metal elements presence. Moreover, the slowness in response to the regulation system actions, necessary to maintain the desired environmental conditions as the heating loads vary, is considered a radiant floor heating system fault; in this paper this aspect has been investigated. A numerical study and an experimental investigation have been conducted, to evaluate the mortar thermal inertia variation due to the presence of metal cylinder elements embedded in the slab. Results show that the time-costant C value is reduced up to 75% compared to pure mortar, and a lower amplitude reduction (damping) on the opposite face of the slab is observed, making this mortar with metal elements a good solution for radiant floor equipments.