The boundary condition at the hot absorber plate in a solar collector will influence the natural convection in the enclosure. For the isoflux boundary condition and an isothermal cold wall an experimental and numerical study has been made for Ra numbers from 105 to 107 and inclinations from 20 to 90 deg with the horizontal. For vertical enclosures the heat transfer by natural convection was about 19 percent above that for an isothermal hot plate. This decreases with angle of inclination, to 9 percent at 20 deg. For solar collectors it means that for cases where the absorber plate is not isothermal the convective losses can be about 10 percent above the usually expected values.

This content is only available via PDF.
You do not currently have access to this content.