Optimum ventilation based on the overall ventilation effectiveness for temperature distribution in ventilated cavities

A numerical study of conjugated heat transfer in a ventilated cavity was carried out in order to analyze temperature distribution effectiveness inside it, and to determine a good ventilation configuration. The space was represented by a ventilated cavity under turbulent flow regime. All the walls were considered adiabatic, except the vertical wall on right, which was defined as a conductive opaque wall with a gap in its lower side for the incoming air. The conductive wall is submitted to a constant heat flux of 736 W/m(2) and it is considered to interact with the outside ambient. Four cases for the air exhaust location were considered for the analysis; the incoming air velocity was varying depending on the Reynolds number between 2 x 10(3) <= Re <= 4 x 10(4). The conductive wall was analyzed for two different materials (construction brick and adobe block) and three different widths each (0.1, 0.2 and 0.3 m). The mass, momentum and energy equations, coupled with the turbulence model k-epsilon were discretized in finite volumes. From the results can be concluded that the 0.3 m width adobe block is the appropriate to minimize thermal load gains to the inside of the room and it helps to reduce the efforts made on ventilation to remove heat. Regarding the air exhaust location, it was concluded that the right side of the upper horizontal wall was the best position for the air exhaust for a Reynolds number between 5 x 10(3) and 1 x 10(4) based on the effectiveness of temperature distribution and velocity according to ASHRAE Standard 55, Thermal environment conditions for human occupancy, 2004 [1]. (C) 2008 Elsevier Masson SAS. All rights reserved.