Fig.Ā 9From: Application-based design of the Fresnel lens solar concentratorFocal heat flux distribution in W/m2 for the Stirling engine application. a Symmetrical real-data points and 2D second-order Gaussian regression from Qandil and Zhao (2018), b 3D second-order Gaussian plotted against receiver dimensions (mm) with COMSOLĀ®Back to article page