Performance of a rectangular secondary concentrator with an asymmetric heliostat field

Secondary concentrators with non-regular cross section have been proposed t o permit additional degrees of freedom in heliostat field design, free of t he limitations imposed by conventional rotationally symmetric concentrators . A new class of concentrators with a rectangular cross section was found b y numerical optimization for heliostat fields having an elliptic contour wi th high eccentricity. An example of such a rectangular concentrator was con structed and tested at the Weizmann Institute, where the heliostat field ha s a strong asymmetry and is poorly suited for symmetric (having regular cro ss section) concentrators. The performance of the new concentrator has been rested using calorimetric and radiometric measurements. The tests were car ried out for several heliostats, located in representative positions relati ve to the predicted acceptance contours of the concentrator. The results of the tests show an agreement with the prediction, and validate the new desi gn for use with highly eccentric fields. A more general conclusion is the v alidation of the approach of optimizing faceted secondary concentrators wit h flexible geometry to match heliostat fields having a wide range of possib le contours. (C) 2000 Elsevier Science Ltd. All rights reserved.