One of the European Directive priorities is represented by the improvement of “building performance requirements” and the development of new strategies for “very low energy buildings” thanks to it is possible to reduce the energy consumptions due to the heat flux transmitted through the envelope of buildings. This paper illustrates a numerical investigation on a system that made possible this goal, in the specific a prototypal ventilated roof for residential use, inclined of 15° respect to the horizontal plane and the results are compared with a configuration with an inclination of 30°. Due to geometric and thermal symmetry the system has been studied considering a single side of the pitched roof. The analysis is carried out on a two-dimensional model in air flow and the governing equations are given in terms of k-ε turbulence model. The investigation is performed to evaluate thermo fluid dynamic behaviors of the ventilated roof as a function of the different conditions applied on the top wall and the bottom wall of the roof in summer and winter regimes. The problem is solved by means of the commercial code Ansys-Fluent on a channel of 6 m of length. The comparison shows that the inclination of 30° is more convenient both in summer and in winter due to the higher mass flow rate inside the channel.
Thermal Evaluation of Natural Convection in a Ventilated Roof under Variable Climatic Condition
Buonomo, Bernardo;Capasso, Lucia;Manca, Oronzio;Nardini, Sergio;
2020
Abstract
One of the European Directive priorities is represented by the improvement of “building performance requirements” and the development of new strategies for “very low energy buildings” thanks to it is possible to reduce the energy consumptions due to the heat flux transmitted through the envelope of buildings. This paper illustrates a numerical investigation on a system that made possible this goal, in the specific a prototypal ventilated roof for residential use, inclined of 15° respect to the horizontal plane and the results are compared with a configuration with an inclination of 30°. Due to geometric and thermal symmetry the system has been studied considering a single side of the pitched roof. The analysis is carried out on a two-dimensional model in air flow and the governing equations are given in terms of k-ε turbulence model. The investigation is performed to evaluate thermo fluid dynamic behaviors of the ventilated roof as a function of the different conditions applied on the top wall and the bottom wall of the roof in summer and winter regimes. The problem is solved by means of the commercial code Ansys-Fluent on a channel of 6 m of length. The comparison shows that the inclination of 30° is more convenient both in summer and in winter due to the higher mass flow rate inside the channel.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
