EXPERIMENTAL STUDY OF TRANSIENT NATURAL CONVECTION IN AN INCLINED POROUS ENCLOSURE WITH TIME-PERIODICALLY-VARYING WALL TEMPERATURE

摘要

The transient natural convection in an inclined enclosure filled with porous media is studied experimentally and numerically for the time-periodically-varying wall temperature on one side wall and constant average temperature on the opposing side wall. This system has no temperature difference between the opposing two side walls in time-averaged sense. The porous media with three kinds of porosity consist of water and three kinds of glass ball with different diameter. The temperature and heat flux across the two above-mentioned walls are measured by a heat flux meter. The effects of inclined angles and porosity of the enclosure on heat transfer characteristics have also been studied. The experimental results show that, with the upper wall temperature oscillating, the heat flux across the enclosure is also periodically varied with time. However, the net heat flux is always from the lower wall to the upper wall and reaches maximum at a certain inclined angle. Numerical computations are also conducted and numerical results are qualitatively assured by the experimental measurements.