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Efficient operation of thermal solar power plants is strongly dependent on the central receiver design. In particular, as the receiver tube determines the temperature behavior inside the receiver, its geometry proves to be the main factor affecting the solar tower receiver performances. This paper investigates the effect of several 3D geometric concepts on both temperature evolution and velocity of the working fluid at the receiver, in order to obtain an enhanced design, with augmented efficiency. A novel receiver tube with helical fins is proposed, aiming an increased heat exchange surface and improved thermal conduction. Extensive numerical simulation is carried out in ANSYS CFX (CFD) to assess the performances of the proposed solar tower receiver design. An unstructured mesh, generated by a computation machine, and (k-ε) turbulence model are employed to this regard. The results show that the tubes with helical fins for solar tower receivers give a very important increase in the outlet temperature, which can reach up to 1050 K.

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Blade geometry is an important design parameter that influences global wind turbine energy harvesting performances. The geometric characteristics of the blade profile are obtained by determining the distribution of the chord and twist angle for each blade section. In order to maximize the wind energy production, implying a maximum lift-to-drag ratio for each wind speed, this distribution should be optimized. This paper presents a methodology to numerically determine the change in the twist angle by introducing a range of pitch angles for the maximum power coefficient case. The obtained pitch values were distributed from the root to the tip of blade. The results prove that the power coefficient increases for wind speeds greater than the rated point, which improves the yearly production of energy by 5% compared to the reference case.

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