Natural convection heat transfer and entropy generation from a horizontal cylinder with baffles

The problem of laminar natural convection heat transfer from a horizontal c ylinder with multiple, equally spaced, low conductivity baffles on its oute r surface was investigated numerically. The effect of several combinations of number of baffles and baffle height on the average Nusselt number was st udied over a wide range of Rayleigh numbers. The computed velocity and temp erature fields were also used to calculate the local and global entropy gen eration for different cylinder diameters. The results showed that there was an optimal combination of a number of baffles and baffle height for minimu m Nusselt number for a given value of the Rayleigh number. Short baffles sl ightly increased the Nusselt number at small values of the Rayleigh number. The global entropy generation increased monotonically with increasing Rayl eigh number and decreased with increasing cylinder diameter, baffle height, and number of baffles.