Comparative study of spiral and conical cavity receivers for a solar dish collector

The objective of this work is to compare two cavity receivers for a solar dish concentrator. The spiral and the conical cavities are investigated using a developed thermal model. The analysis is optical, thermal and exergetic for different operating temperatuies and flow rates. The developed thermal model is combined with an optical tool in order to simulate properly the solar dish collector and it is validated for the case of the spiral absorber with experimental results. Every receiver is separated in the different coil and every coil is simulated separately in order to increase the model accuracy. Totally, 13 coils are used for the spiral design and 11 for the conical design. The location of the receiver in every case is optimized in order to achieve maximum optical efficiency. The results show that the conical design leads to a 1.38% increase in the optical efficiency due to the increased intercept factor. The thermal efficiency enhancement with the use of conical design is found to be 5.63% at 100 degrees C and 40.45% at 200 degrees C, while the exergy efficiency enhancement 6.67% at 100 degrees C and 42.06% at 200 degrees C.