EXPERIMENTAL RESULTS FOR NATURAL CONVECTION HEAT TRANSFER IN A CAVITY WITH FLUSH MOUNTED HEAT SOURCES Ricardo Alan Verdú Ramos UNESP – Campus de Ilha Solteira – Departamento de Engenharia Mecânica Av. Brasil Centro, 56 – Ilha Solteira, SP – 15385-000 ramos@dem.feis.unesp.br Alessandro Tomio Takaki UNESP – Campus de Ilha Solteira – Departamento de Engenharia Mecânica Av. Brasil Centro, 56 – Ilha Solteira, SP – 15385-000 takaki@dem.feis.unesp.br Giancarlo de Souza Damno UNESP – Campus de Ilha Solteira – Departamento de Engenharia Mecânica Av. Brasil Centro, 56 – Ilha Solteira, SP – 15385-000 damno@dem.feis.unesp.br Abstract. In this work, a experimental study of the natural convection heat transfer in a cavity with discrete heat sources flush mounted in one of the walls, simulating electronic components, is carried out. The inferior and superior walls are insulated and the temperature of the opposite wall to the one with heat sources is maintained constant, lower than the environment temperature. The influence of power dissipated by the sources, the cooling temperature, the aspect ratio and the inclination angle of the cavity with respect to the horizontal plane, on the flow and the heat transfer, have all been evaluated. Cubic cavities were built and experimental tests for measure of the temperature was realized by using thermocouples and a data acquisition system controlled by computer, being obtained the temperature fields inside the cavity, as well as the temperature distribution in the wall where the heat sources are mounted. The results were compared with respect to the maximum temperature in the cavity, that is the parameter of larger interest in the problem. Additionally, flow visualization was realized by using the smoke tracing technique generated by burning incense. Keywords. Natural convection, thermal cavity, heat sources, temperature measurements. 1. Introduction Among all the environmental factors, temperature is by far the main responsible for electronic component failures. In fact, the flaw rate increases almost exponentially with the operating temperature (Peterson & Ortega, 1990). Due to the ever-escalating miniaturization of the components, heat flux by unit of volume has been on the increase followed by the temperature levels and consequently increasing the possibility of failure. Therefore a thermal study becomes highly desirable, moreover in the most critical case in which natural convection seems to be the main mechanism of heat transfer, as in electronic components mounted in a closed cavity. Among the works on this subject, considering a number of different geometries and contour conditions, some can be mentioned: Keyhani et al. (1988), Chadwick et al. (1991), Du and Bilgen (1992), Ho and Chang (1994), Hsu et al. (1997), Ramos et al. (1998), Sezai and Mohamad (2000), to name but a few. φ L = 200 mm H/L = 1/8, 1/4 and 1/2 TC = 15, 20 and 25 °C Q = 1, 3 and 5 W φ = 0, 45 and 90° Depth = 150 mm Figure 1. Thermal cavity with flush-mounted heat sources in one of the walls, simulating electronic components. Q Q Q Q