Study on Spectral Radiative Heat Transfer Characteristics of a Windowed Receiver with Particle Curtain

In this paper, a windowed receiver with a particle curtain is numerically simulated under full-spectrum conditions. The discrete phase model (DPM) is used to model the particle flow and interactions between the particle phase and the air phase. The scattering, absorption of the particle curtain and quartz glass window are considered in detail. The spectral characteristics of glass have an important influence on the heat transfer characteristics and the receiver efficiency. The results show that the quartz window can reduce the convective heat loss and the cavity re-radiation heat loss. Under the same conditions, the receiver efficiency of a windowed receiver with a particle curtain is increased by 11.9% compared with an aerowindow receiver with a particle curtain. Under the same mass flow, the particle curtain thickness and particle size have a non-negligible influence on the flow pattern and temperature distribution of the particle curtain. When the particle curtain thickness is low, the flow stability of the particle curtain is high; as the particle curtain thickness increases, the volume fraction of the particle curtain decreases, and the flow stability of the particle curtain decreases, which affects the shape of the curtain. The scattering and absorption characteristics of the particles are different, resulting in different net fluxes of incident radiation under the reflection of the particle curtain and the back wall. As the particle curtain thickness increases, the particle average exit temperature and the receiver efficiency show a trend of first increasing and then decreasing. When d = 30 mm, the incident radiation (G) at the position of the particle curtain is larger, the particle average exit temperature reaches 1156.72 K, and the receiver efficiency reaches 74.4%. Therefore, different particle sizes also have a significant impact on the flow pattern of the particle curtain and the radiation distribution inside it. In the range of 250–750 μm particle size, the particles average exit temperature reaches above 1150 K, and the receiver efficiency is above 72.6%. As the particle size increases, the particle average exit temperature, and the receiver efficiency show a trend of first decreasing and then increasing. When the particle size is 500 mm, the particle average exit temperature reaches 1175.8 K, and the receiver efficiency reaches 79.4%.