Experimental Investigation on Heat Loss from Solar Scheffler Receiver
Convection heat loss occurs in receivers of high concentrating solar concentrators, Solar Scheffler, downward focusing systems and solar towers. In most applications, it can contribute a significant fraction of total energy loss, and hence it is an important determining factor in system performance. Solar concentrators are especially located in an open environment with wind flow on the receiver surface. This wind flow has the major effect on heat loss when the flow direction is parallel to the receiver plane or at an angle. All the concentrators are needed to be track during the operation and hence the position of the receiver is changing continually. In case of the Scheffler applications Scheffler’s are provided with tracking mechanism while receivers are fixed. The angle between the wind flow and the receiver axis will then play an important role in the heat loss. In this study lab experimental setup was developed to predict the heat loss from receiver with experimental simulation. To investigate convection lose from receiver, an electrically heated model receiver, was tested for different combinations of angle between the receiver and wind. Wind angle was varied from 0 deg (wind parallel to receiver surface) to 90 deg (wind perpendicular to receiver surface) with average receiver surface temperatures 100 and 110°C. It is observed that at 90 deg. Angle heat loss was maximum. Heat loss measurement was carried for three combinations of wind skirt that has an angle of 15, 30 and 45 deg. It is observed that the heat loss was minimum for 30 deg wind skirt angle. For wind angle of 67.5 and 90 deg sharp rise in heat loss was noted at higher velocities.
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