First-of-a-kind demonstration of a direct hybrid between a solar receiver and the radiant burner technology

The use of hybrid solar thermal devices, which harness the energy from both concentrated solar radiation and combustion, is receiving growing attention due to their potential to provide a firm and dispatchable thermal energy supply while lowering the costs of energy systems and assisting the penetration of renewable energy. Direct hybrids, which integrate the functions of both a solar receiver and a combustor into a single device, feature the greatest potential in terms of high efficiency, cost-reduction and flexibility in operation, among all the hybrid design proposed to date. In this study, we propose a novel concept of direct hybrid, which integrate the functions of the radiant burner, RB, technology into a billboard-type solar receiver. RB technology was selected here given its potential to provide high radiative heat transfer and heat fluxes similar to those of concentrated solar radiation. First-of-a-kind, systematic measurements of the performance of a 20-kW laboratory-scale Hybrid Solar Radiant Burner Receiver, HSRBR, unit are reported here under simulated solar conditions and using natural gas as energy source for combustion and mixed operations. It was found that the device can achieve thermal efficiency of up to 80% and provide firm supply of hot air of up to 700 °C. Also, it was found that the RB can efficiently manage transients with a fast response time, so that the device can provide both a steady thermal output and a constant outlet temperature of the heat transfer fluid. The location of the RB within the solar receiver (either in the front or back of the billboard-like heat exchanger) was found to have only a small influence on the performance of the device, indicating a great design flexibility.