A numerical simulation on recirculation phenomena of the plume generated by obstacles around a row of cooling towers

The present paper addresses the recirculation phenomena of the plume generated by obstacles around a row of cross-flow type forced draft cooling towers. In order to consider the interaction between external and internal flow of the cooling tower, both outside and inside of the cooling tower are involved in a computational domain. A three-dimensional in-house program based on a non-orthogonal, non-staggered and unstructured grid system is employed. The standard k-ε turbulence model is used for the turbulent effect. In order to analyze flow and heat/mass transfers in the cooling tower, the continuity, momentum, moisture fraction and enthalpy equations have been considered for both air and water. The density and moisture fraction for air and water are obtained by using the function of thermal properties. The geometrical parameters investigated in this research are the height of obstacle, the distance between the inlet region of cooling tower and the obstacle wall, existence of the air-guide and effects of front and rear obstacles. The results show that the mean moisture fractions in the cases with air-guide are, in general, lower than the cases without air-guide under the same conditions. Also, in the cases without air-guide, the mean moisture fraction increases as the obstacle height increases. In addition, it is observed that for the cases without the air-guide with the increase in the distance between the tower and obstacle, the mean moisture fraction is decreased. However, the cases with air-guide do not follow a specific pattern in the same situations.