Optimized solar thermal concentrator system based on free-form trough reflector

•A free-form (FF) surface creation (FFSC) method is proposed.•A concentrator with free-form trough (FFT) has been proposed.•The FFT concentrator guides all of the incoming rays onto the receiver surface.•The FFT concentrator improves the irradiance distribution uniformity.•The irradiance distribution of FFT concentrator almost matches the ideal value.

A solar thermal concentrator system is proposed comprising a free-form-trough (FFT) reflector and a cylindrical heat-pipe receiver. The profile of the reflector is designed using a free-form surface creation (FFSC) method such that each incident ray is directed to a certain user-specified point on the heat-pipe surface. The light ray paths within the concentrator system are analyzed using a skew-ray tracing approach. A method is then proposed for optimizing the geometry of the concentrator system in such a way as to achieve a uniform irradiance distribution on the heat-pipe surface. The validity of the proposed optimization approach is demonstrated by means of ZEMAX/SolidWorks-Flow simulations. The results show that the proposed FFT concentrator yields a significant improvement in both the irradiance uniformity and the heating efficiency compared to conventional cylindrical-trough and parabolic-trough concentrators.