Experimental and numerical analyses of natural convection flow in a partially heated vertical annulus

Experimental and numerical analyses have been carried out for single-phase natural convection thermally induced flow in an internally heated vertical annulus. The experiments are performed on an in-house setup having an internally heated annulus of aspect ratio 352 with the heat flux ranging from 2.5 kW/m² to 15 kW/m². Water is used as the working fluid. The numerical simulations are carried out by a computational fluid dynamics (CFD) model developed using the commercial software package Ansys Fluent. The results of the present analysis are then compared with the experimental data. There is an excellent agreement between the numerical and the experimental results. The contour plots are presented for temperature, velocity, and thermal boundary layer. The thermal boundary layer thickness decreases while the thermal entry length increases with heat flux. An increase in the heat flux leads to the increase in the heat transfer coefficient and the Nusselt number.