(396a) Performance Characteristics of a Directly-Irradiated Windowless Solar Vortex Particle Receiver

We report a first-of-a-kind experimental study on the performance characteristics of a novel windowless directly-irradiated vortex-based solar particulate vessel, the Solar Expanding Vortex Receiver-Reactor (SEVR). A laboratory-scale SEVR was built and tested at a nominal capacity of 6-kWth using silicon carbide as particulate heat transfer media and a solar simulator to generate the concentrated solar radiation. A vacuum pump was used to generate a sufficiently large suction at the outlet section of the device in order to avoid particle egress through the aperture while operating the device under windowless conditions. Particle egress, flow visualisation at the aperture plane and bulk gas flow rate measurements were also carried out under iso-thermal conditions and different suction values to identify suitable conditions for carrying out hot tests. The key operating parameters, namely particle size, particle loading and gas volumetric flow rate were systematically varied to assess their influence on the thermal performance, wall cavity distribution and heat losses within the device as well as to determine the complex mechanisms controlling the behaviour of the two-phase flow in the SEVR. It was found that the improved aerodynamic of the device allows to mitigate the radiative heat losses in comparison with previous vortex-based receivers as the maximum temperature peak occurs at the opposite end to the aperture. It was also found that the the thermal performance are significantly influenced by all the parameters investigated. Particularly, the mean particle residence time, which is controlled by the particle size and gas flow rate, is a key controlling parameters influencing the maximum efficiency and temperature distribution within the device. The present investigation demonstrates for the first time that directly-irradiated vortex-based receiver technology can be efficiently operated without a window, which is the key limiting factor for scaling-up of such devices while also being a costly component subjected to damage and potential failure. The device can be employed in power generation, fuel production and high-temperature industrial processes (sensible heat, material processing) that can allow a small amount of air ingress into the receiver-reactor.