Experimental and numerical study of conjugate heat transfer in an open square-cavity solar receiver

Combined heat transfer mechanisms in open cavities is a relevant research topic because of its direct application in the design and thermal characterization of solar receivers'prototypes. These devices have several applications, for example, solar furnaces and solar tower systems where a central receiver is used to increase the temperature of a working fluid, which is then employed to produce electricity. So that can reach temperatures above 500 C because they are designed to trap concentrated solar radiation, and due to high temperatures, the predominant heat transfer phenomena are natural convection and radiative heat transfer. This paper presents a numerical and experimental heat transfer analysis of an open square-cavity solar receiver. The numerical study was carried out considering laminar flow in an open square-cavity with Rayleigh numbers (Ra) of 104, 105 and 106. For the radiative heat transfer, the study considered both transparent and radiatively participating media. The results show difference in both cases and exhibit the importance of taking into account a radiatively participating media. An acceptable comparison was obtained with the experimental results.