Experimental Study on Convective Heat Loss from a Fully Open Semi-Cylindrical Cavity Receiver

Natural convection heat loss contributes a significant fraction of total energy loss in cavity-type receivers in solar concentrating systems. To investigate the convective loss, an electrically-heated fully open semi-cylindrical model receiver was tested at inclination angles from 0° (side-facing) to +90° (downward-facing) and different input powers. The experimental results show that the cavity surface temperature rises by increasing inclination angle which causes an increase in radiative and conductive heat loss. The convective heat loss from cavity receiver decreases from 41% of total heat loss at 0° to 20% at +90°. Furthermore, the Nusselt number decreases by increasing the inclination angle and has the lowest value at +90°.

Keywords:

Semi-cylindrical cavity receiver , Heat transfer , Convection heat loss , Nusselt number