ANÁLISE DA EFICIÊNCIA DE PAINÉIS CUSTOMIZADOS PARA RESFRIAMENTO RADIATIVO NOTURNO POR SIMULAÇÕES EM CFD

Abstract

In Brazil, energy consumption in buildings is mainly due to cooling indoor spaces, especially with the use of air conditioning systems. Thus, this study aims to evaluate the thermal performance of a radiative panel in a nocturnal radiative cooling system by means of computer simulations. The water flow inside the inner cavities of the radiator enabled the verification of the thermal gradient between the intake and outlet of the fluid. The proposed system included one 220 l water tank, a water pump, one 20 l intermediary water tank, and a custom panel made from eight sections of a standard extruded aluminum profile. Atmospheric conditions were collected in three nights in February 2021 in Curitiba, Paraná. Outside air temperature and relative humidity were monitored, as well as the temperature of the water inside the panel. The measured data was compared to the results of predictive equations under the same atmospheric conditions. Then, CFD (computational fluid dynamics) simulations were carried out to predict the panel’s best thermal performance during night time. Those simulations also enabled the definition of its best sections´ arrangement for the same period. The comparison between the results from measured data, the equations and the simulations suggests that the CFD simulation is a viable tool to predict the custom panel’s performance. Moreover, this study concludes that the system efficiency depends on a short water path inside the panel.