Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Mechanical Power Engineering

In the current study, a computational fluid dynamics model was developed using volume averaged Navier-Stokes equations and porous thermal equilibrium model to investigate the performance of the solar volumetric receiver against the change of a set of parameters such as: main air inlet velocity, return air temperature, return air velocity and return air inlet orientation. The model was validated against previous experimental results with maximum outlet temperature deviation of 7.3%. A new geometry influenced by the HiTRec receiver design was proposed in order to take into account the effect of return air on receiver{u2019}s performance, also to modify the outlet zone of the receiver in order to minimize flow separation and reversed flow. The current study concluded that plants installed at locations of high wind speeds will result in poor performance of the volumetric receiver, and also showed that the thermal efficiency decreased by 14% when the inlet velocity increased from 0.2 to 1.2 m/s, moreover, using high porosity absorbers is not necessarily an advantage due to the high thermal gradients that lead to high thermal stresses, the possibility of occurrence of flow instability and distortion or failure of the absorber

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