A numerical radiation model for the centrifugal particle solar receiver.

The centrifugal particle solar receiver (CentRec) is a promising technology to reduce the cost of heat and electricity generated by solar towers. In this study, a computationally inexpensive radiation model accounting for all radiative heat transfer mechanisms in the CentRec is addressed. A short-range radiation model to calculate the radiative heat transfer between close particle pairs and a radiation enclosure model to calculate diffuse radiation heat exchange between large surfaces of the receiver are developed. Moreover, a radiation penetration model to distribute the solar energy to particles, which was developed by authors previously, is integrated into the main model. The models are applied to a small-scale receiver and thermal steady state results are obtained. The model is compared with an in-house Monte Carlo ray tracing code for the case of a uniform heat flux of 3 MW/m^2 at the aperture. The results show that although the developed model matches particle outlet temperature by a narrow margin (10 K), the temperature distribution in the receiver is overestimated slightly by the current model. Moreover, while the current model calculates around 3.5% of reflection and emission loss, MCRT-based model gives around 5.5% of total radiative loss for the given solar flux distribution. Thus, there is still room for improvement. [ABSTRACT FROM AUTHOR]