The Wind Test on Heat Loss from Three Coil Cavity Receiver for a Parabolic Dish Collector

The heat loss from cavity receiver in parabolic dish system determines the efficiency and cost effectiveness of the system. A modified three coil solar cavity receiver of inner wall area approximately three times of single coil receiver, is experimentally investigated to study the effect of fluid inlet temperature (Tfi=50 degrees C to 75 degrees C) and cavity inclination angle (theta = 0 degrees to 90 degrees) on the heat loss from receiver under wind condition for head on wind and side on wind velocity at 3 m/s. Overall it was found that the natural and forced convection total heat loss increases with increase in mean fluid temperature. The combined heat loss decreases sharply with the increase in cavity inclination and observed to be maximum for horizontal position of receiver and minimum with the receiver facing vertically downward for all investigations. The maximum heat loss in wind test (V=3m/s) is 1045 W at theta=0 degrees cavity inclination at mean fluid temperature 68 degrees C and minimum at 173 W theta=90 degrees at 53 degrees C. Total heat loss from the receiver under wind condition (V=3m/s) is up to 25% higher (1.25 times at 0 degrees inclination) than without wind at mean fluid temperature similar to 70 degrees C and minimum 19.64 % (1.2 times at 90 degrees inclination) in mean temperature similar to 50 degrees C. In horizontal position of the receiver (theta=0 degrees), the total heat loss by head on wind is about 1.23 times (18% higher ) as compared to side on wind (at fluid mean temperature similar to 70 degrees C). For receiver facing downward (theta=90 degrees), for head-on wind, total heat loss is approximately the same as that for side-on wind.