An experimental study has been performed on natural convective heat transfer in inclined enclosures heated from below, and with partitions running in the up-slope direction (see Fig. 1). The influence of a clearance between the partitions and the lower heated isothermal surface is considered. This problem is of particular importance in solar collector design. Heat transfer rates have been measured for Ra < 107, enclosure inclination of 0, 30, 60, and 90 deg from the horizontal, and partition end clearances ranging from zero up to half the enclosure height. A flow visualization study which covers the same range of inclinations and end clearances is also reported. It is shown that introducing a small partition end clearance has no significant effect on the flow or heat transfer rates. However, a large end clearance allows up-slope rolls to be established in the unpartitioned region of the enclosure, resulting in an increase in the heat transfer rates. The natural convective heat transfer rates are found to be independent of both partition end clearance and enclosure inclination over certain ranges of these parameters. The convective heat transfer characteristics are also shown to be related to the flow.
Experimental Investigation of Heat Transfer Rates and Pressure Drops through Compact Heat Exchangers
