Numerical and Experimental Investigation of the Wind Influence on Scaled-Up Open Volumetric Cavity Receivers

Kurzfassung

Solar tower power plants have the potential to become a valuable asset in renewable electricity and heat generation. Among the available receiver technologies, the open volumetric air receiver (OVR) offers a high level of technical readiness, robustness and the potential for high temperature applications with effective storage capabilities. Tests at the Solar Tower in Jülich have demonstrated the availability and promising receiver efficiencies at the level of a 1.5 MWe demonstration plant. Ongoing research projects at DLR are investigating the potential of the OVR in a scaled-up tower concept. The proposed design uses a multi-receiver concept where the receivers are arranged in cavities to further increase the receiver efficiency. A scale-up to 50 MWe is realized with tower heights of around 200 m, which increases the relevance of ambient wind. Compared to closed-loop surface receivers, the OVR is particularly sensitive to fluctuations in ambient conditions due to the open process design. To investigate the wind influence on cavity OVRs, the surface pressure distribution was analyzed in wind tunnel experiments under a range of wind conditions with Reynolds numbers up to 13.17E06. In addition, numerical simulations based on RANS and DES approaches were performed to further investigate the interaction between the receiver flow and the ambient wind. The CFD model was successfully validated against the experimental results and surface pressure fluctuations could be quantified for the expected wind conditions. Furthermore, the wind influence on the air return ratio and receiver efficiency of the cavity design is numerically evaluated for different wind speeds. In addition to that, counter-measures regarding the return air distribution are numerically evaluated to increase the receiver efficiency.