EXPERIMENTAL AND CFD INVESTIGATION OF SOLAR CENTRAL RECEIVER TUBES

Abstract

Lower electricity cost corresponds to high efficiency, which in turn corresponds to high operating temperatures in Concentrated Solar Power technology. Central receiver of such system constitutes 15% of the cost and plays an important role in achieving high operating temperatures. Central receiver systems are composed of tubes with heat transfer fluid flowing inside them that transports heat from radiation on the outer wall of tubes. Circular cross-sectional tubes are conventionally used for this application, but many different variable geometry tubes have been proposed for better heat transfer. Numerous experiments have shown the enhanced heat transfer behavior of different corrugated tubes. This work proposes a tube of new cross-sectional geometry and performs experiment using water as heat transfer fluid. The experiment is conducted on four different samples of corrugated tubes adopted from literature and compared to a circular tube and a new proposed tube. The experimental and CFD results are compared and reported. It is found that the new tube design can be used for such heat transfer applications but is not an ideal option. Meanwhile, corrugated tubes have higher heat transfer than circular tube, but not without the addition of extra material and pressure drop. If the material is to be kept similar for all tubes, circular tube is found to be the best option for central receiver systems.