Study on heat transfer and stress characteristics of the pressurized volumetric receiver in solar power tower system

In this paper, the analysis of heat transfer and stress characteristics in pressurized volumetric receiver (PVR) is presented by coupling Monte Carlo Ray Tracing (MCRT), Finite Volume Method (FVM) and Finite Element Method (FEM). Firstly, an integration model coupling MCRT, FVM and FEM applied in PVR is developed. Based on this model, the coupled characteristics of optical-thermal-stress are numerically studied. Meanwhile, the solar flux is homogenized using multi-point aiming strategy for multi-heliostat field zones. Finally, the effects of air mass flow and inlet temperature on the heat transfer and stress characteristics are discussed. The results indicate that the solar flux distributions on aperture and SiC porous absorber are more uniform using multi-point aiming strategy, and the peak flux in porous could be reduced by an order of magnitude compared with single-point. The peak stress of quartz window occurs at the contact position between the steel shell and quartz window, and the damage would not happen because of the peak stress is lower than the ultimate strength. The inlet parameters of air have significantly influences on the heat transfer and stress characteristics of receiver. For example, when the air with higher temperature is adopted, the SiC porous temperature increases by 20%, and the temperature and stress of quartz window increase by 31% and 60%, respectively. The overheating in SiC porous could occur using lower mass flow rates, however, the quartz glass stress exhibits a decreasing tendency when the mass flow decreases. Besides, the temperatures of outlet air and porous absorber increase when the flow rate decreases and inlet temperature increases which would lead to local overheating in absorber and lower stress on quartz window.