Ray Tracer for Analysis of Solar Concentrating Systems
Abstract
Solar concentrating systems are designed to provide solar energy at high temperatures. The sizes of solar systems range from large scale power plants to small scale household systems, where thermal heat is collected for heating and cooking purposes. A ray tracer can be useful when designing the reflection and absorption components of solar concentrators, in particular for complex systems with several components in a non symmetric 3D arrangement. Emitted sun rays are traced from the source through all reflections until they intercept with the receiver or are lost past all of the components. A 3D ray tracer method to simulate and analyze solar concentrating systems is presented. The algorithm of the ray tracer and a vectorized implementation of it (in MATLAB) is presented. The ray tracer has been programmed as part of an effort to develop small scale concentrating solar energy systems with integrated heat storage units. The ray tracer is demonstrated for selected cases where a comparison between continuous reflecting surfaces and flat mirror tiled surfaces is made. Off focus sensitivity analysis can provide guidelines for the required solar tracking accuracy. Sensitivity analysis on the size of mirror tiles can be made, in relation to the absorber geometry. Ray tracing computations have in particular been useful when analyzing double reflection systems, where a primary reflector with focus on a secondary reflector which focus further onto the absorber. Such systems become sensitive to the accuracy and to the geometry of the reflecting elements.