Experimental study on transient natural convection in à cube enclosure with an isolated vertical cyclically heated plate

The low frequency cyclical transient natural convection in a cube enclosure with an internal isolated vertical heated plate was investigated experimentally. A computer-aided experimental system was designed to generate the cyclical heating power input and also used for data reduction. The effects of the cyclic heating power input amplitude (from 0 to 8 W) and frequency (from 1/5400 s^-1 to 1/600 s^-1) as well as the per-cycle time-average power input (from 8 to 24 W) on the transient and time-average Nusselt number were parametrically studied. It was found that for such cyclical transient natural convection with low frequency, the plate heating power input amplitude and frequency have little effects on the time-average Nusselt number as long as the cyclical time-average heating power input remains the same, although the transient Nusselt number may be significantly affected. Therefore, the modified Grashof number based on the plate average heat flux can be used to characterize the time-average heat transfer process. The plate time-average Nusselt number is about 15% less than the infinite-space Nusselt number. The location of the isolated plate in enclosure does not appreciably influence the time - average heat transfer characteristics of the plate.