Free convective heat transfer induced inside a vented duct having two aligned hot and cold cylinders: An experimental study

Free convective heat transfer created from two aligned cylinders immersed inside a vented air duct is experimentally investigated. The experiments include the measurements of cylinders temperature and the air temperature inside the enclosure under steady, turbulent, and incompressible flow properties by using steady-state heat equations. The studied parameters include Rayleigh number (${10}^5\le \mathrm{Ra}\le {3.4\times 10}^6$), opening sizes at lower and upper enclosure surfaces ($0.146\le O\le 1$), and space size between cylinders ($0.35\le S\le 0.532$) with the constant ratio of enclosure width to cylinder diameter equal to 6. The findings displayed that the average air temperature inside the enclosure for the low values of S and O is low, and it rises as S is raised. The behaviors of Nu differ with changing Ra values. An interaction between hot cylinder and cold cylinder inside the enclosure is observed that depends on O and S values, and hence, they have a large impact on fluid temperature. The data indicated that $\mathrm{Nu}$ rises with the $\mathrm{Ra}$ for all $S$ and $O$ values. The value of $\mathrm{Nu}$ for each cylinder depends on the values of $S$ and $O$. The maximum $\mathrm{Nu}$ value has been obtained when $O=0.439$ and $S=0.35$ with maximum enhancement between 30% and 50% depending on Ra values as compared with $O=0.146$ and $S=0.523$, whereas the minimum average $\mathrm{Nu}$ has been indicated when $O=0.146$ and $S=0.35$. The profiles of $\mathrm{Nu}$ reveal that $O$, $\mathrm{Ra}$, and $S$ have a considerable influence on heat transfer.