Natural convection heat transfer from a vertical column of finite number of heated circular cylinders immersed in molten solar salt

摘要

A two-dimensional steady-state natural convection heat transfer from a vertical column consisting of 210 tightly packed isothermally heated horizontal circular cylinders submerged into molten solar salt was investigated numerically by using the finite volume method. Although laminar natural convection from a vertical column of multiple horizontal cylinders has been investigated in previous studies (Chouikh et al., 1999; Sparrow and Niethammer, 1981; Bejan et al., 1995; Sadeghipour and Asheghi, 1994; Corcione, 2005; Ashjaee and Yousefi, 2007; Tokura et al., 1983; Hannani et al., 2002; Kitamura et al., 2016), there are very few studies that considered natural convection heat transfer from circular cylinders immersed in molten solar salt (Lu et al., 2016, 2013; Brosseau et al., 2004). The results of the study show that Rayleigh number and longitudinal cylinder spacing S-L have a significant effect on flow and heat transfer in the cylinder column.Using the correlations proposed for natural convection heat transfer from a vertical column of N circular cylinders in air or water would result in large errors in predicting heat transfer for a vertical column of cylinders in molten solar salt. Thus, correlations for the steady-state average Nusselt number (Nu) over bar (D,N) for the column of N circular cylinders, where N was varied from 2 to 10, and for individual cylinders in the column (Nu) over bar (D),(i) are proposed as functions of the Rayleigh number (range 10(4)-10(7)) and dimensionless longitudinal cylinder spacing (S-L/D). New correlations developed specifically for molten salt are needed to improve heat exchanger design for solar heating and heat storage technology, nuclear reactor safety, and waste heat recovery applications. (C) 2019 Elsevier Ltd. All rights reserved.