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Numerical analysis of free convection in a solar collector with non-uniform boundary condition

In the paper the free convection inside closed air container with isothermal non-uniform boundary condition has been analysed numerically. The mathematical model based on Oberbeck mathematical model of boundary layer has been defined. This model has been used to solve the two-dimensional transient heat transfer problem. Fields of relevant thermodynamic dimensions’ characteristics, such as velocity vectors, stream function and temperature gradient have been calculated using finite volume numerical method. A computer solver for transient two-dimensional heat transfer has been developed. The influence of Rayleigh number on different flow and heat convection regimes has been analysed for different inclination angles. An impact of different flow regimes on heat convection has been also analysed using local and average Nusselt numbers. Results have been applied to prediction of free convection heat losses in an approximated model of solar collector for different inclination angles.

free convection; solar collector; finite volume method; heat losses; Rayleigh number; local and average Nusselt number

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