Recirculating metallic particles for the efficiency enhancement of concentrated solar receivers

The use of Concentrated Solar Power technology for energy generation relies on the heating of fluids to high temperatures. One of the limitations of this technology is the low working efficiency of current solar receivers which hinders its application and utilization as a renewable clean energy source. This paper presents a novel concept to improve concentrated solar receiver efficiency through the recirculation of solid particles laden flow within the receiver. The recirculating characteristic of the fluid and solid particle mixture is expected to generate higher output fluid temperature than conventional solar receivers. This is expected to lead to significant improvements in the working performance of the concentrated solar receiver. The numerical study investigates this concept, using a commercial CFD package, employing the discrete particle model (DPM), a RNG k-ε flow model and a discrete ordinate (DO) radiation model. It is found that the use of recirculating solid particles improves the energy absorption within the receiver and with it the thermal efficiency of the proposed solar receiver reaches to around 70%. Moreover, comparing this with a conventional solar receiver, this new concept exhibits a more uniform temperature distribution inside the cavity, which is mainly due to the recirculating flow characteristic and the well-controlled mixing of air and particles. The advantages of this novel concept of the solar receiver present its potential benefits in further applications in the process of energy conversion providing on enhanced heat transfer medium.