Analysis of Volumetric Absorption of Solar Energy and Its Interaction With Convection

A theoretical analysis of the interaction of volumetric absorption of concentrated solar radiation and convection in a two-dimensional, axisymmetric absorption chamber is presented. Previous analytical works on the absorption of the radiant energy in such chambers have employed one-dimensional models to show that very high temperatures and therefore high thermodynamic efficiencies are achievable. In this work, the effects of using collimated as opposed to isotropic irradiation on the absorption efficiency are investigated for the one-dimensional case, and the effects of employing a more realistic two-dimensional model on the absorption efficiency are studied. The model is based on the assumptions that the velocity profile is uniform and that conduction within the fluid is negligible compared to convective and radiative transports of energy. Several parameter surveys are performed and compared with the results of previous one-dimensional models.