A two-parameter aiming strategy to reduce and flatten the flux map in solar power tower plants

Abstract

In surrounding solar power tower plants, the collector field is designed with all the heliostats pointing to the cylindrical receiver equator to obtain maximum intercept. However, in commercial plants, the addition of thousands of energy spots at the same receiver level causes an excessively high peak heat flux of about 2 MW/m2. Therefore, this peak flux should be almost halved to avoid receiver problems due to creep and fatigue effects. The single-parameter aiming strategy (Vant-Hull, 2002) has already shown its ability to divide this high peak flux into two lower peaks; it consists in moving the hot spots up and down from the equator, in alternative heliostat rows, to create symmetric flux maps although they are clearly not very homogeneously distributed along the receiver height. In this work, a slight variation of the single-parameter aim strategy, simply proposing two aim parameters, has been successfully tested for a commercial solar power tower plant with a regular layout. The new two-parameter aiming strategy achieves not only reasonable peak flux values, but also an acceptably flattened flux profile and a slight reduction in spillage compared with the single-parameter strategy.