CONVECTION-CONDUCTION MODEL FOR A TROMBE WALL CONFIGURATION

Taynara Geysa Silva do Lago¹; Kamal Abdel Radi Ismail¹

¹ UNICAMP

doi:10.20906/CPS/CILAMCE2017-1000

Resumo

Trombe wall is an indirect gain passive solar system which was designed and patented with the purpose of supply heating and ventilation in buildings using solar radiation. Since then, Trombe wall has been the subject of several studies aiming to improve its thermal performance. In the literature, there are theoretical studies that have predicted the behavior of the Trombe wall system considering thermal network approach while others have used CFD. The present study handles the conjugate heat transfer problem in a square cavity heated on one wall and cooled at the other parallel wall having an internal conducting solid body. The model is based on the equations of mass conservation, momentum and the energy equations. The discretization of the equations is realized by using the finite volume method in conjunction with the power-law scheme. For The coupling of pressure and velocity fields we used the SIMPLE algorithm while the TDMA method was used in the solution of the equations. The results are reported in the form temperature and streamlines fields for Prandtl number of 0.7, Rayleigh number of 103 to 106, internal solid different sizes, and for a ratio of the thermal conductivities of the solid and fluid varying from 20 to 200. It was found that the increase of the thermal conductivity of the solid reduces the temperature gradient within the cavity. Within the same limits of Rayleigh number and size of solid, the increase of the thermal conductivity of the solid reverts part of the heat transferred from the fluid to the solid wall back to the fluid flow before reaching the cold wall. This reduces the Nusselt number of the cavity to values lower than those for the case without solid wall. As the solid size increases and extends beyond the thermally inactive region, the Nusselt number also becomes dependent on the body size and its thermal conductivity.

Palavras-chave: Natural convection; Thermal wall; Cavity; Trombe wall; Passive comfort