Effect of Different Arrangements of V-Shape Ribs on the Performance of an Optically-Enhanced Parabolic Trough Solar Collector

In this paper, a V-shape ribbed tube is utilized to improve the thermal performance of a parabolic trough collector (PTC). Six different rib arrangements are employed, and a detailed analysis is presented. In addition, the effect of adopting a secondary reflector (SR) on the temperature distribution around both a smooth and a ribbed parabolic trough receiver (PTR) tube is conducted. A computational fluid dynamics model is employed to study the heat transfer and fluid flow characteristics inside the tube. Results show that V-shape ribs are an effective tool to stir up the flow and increase the velocity gradient of the fluid near the inner surface of the tube. This helps increase the convective heat transfer rate and reduce the tube's maximum circumferential temperature. Moreover, results from the study show that the secondary reflector contributes to a further decrease in the tube surface temperature and hence improves the overall thermal efficiency of the collector. The combination of a V-shape ribbed PTR tube and a secondary reflector is thus shown to be beneficial for the PTC system, especially at high Reynolds numbers.