The effect of different diffusers designed for empty cells in central air handling units on flow and pressure drop

Abstract

In this study, three different diffusers (V profile perforated, flat anemostat type, and pyramid anemostat type) have been designed in order to spread the air in shorter distance in empty cells used in central air handling units. The pressure drop caused by these diffusers has been investigated experimentally. The diffusers are mounted at the center of the fan outlet section, up or down the center (the center deflection ratio) and at different distances horizontally (the center distance ratio). It has been determined that the positioning of the diffusers at different distances from the fan outlet section horizontally has a significant effect on the pressure drop. As a result of the experimental study; among the three diffusers, the lowest pressure drop has been obtained from the pyramid anemostat type diffuser. The effect of the position of this diffuser in the empty cell on the flow distribution has also been investigated numerically. The numerical studies have been performed in the ANSYS-Fluent 18.1 program. In the empty cell, the velocity distribution closest to the homogeneous has been obtained by mounting the pyramid anemostat type diffuser at the position where the center distance ratio was 0.017 (5 mm distance from the center) and the center deflection rate was 1.14 (20 mm upward from the center). The minimum pressure drop value has been obtained in the position where the center distance ratio was 0.35 (105 mm away from the center) and the center deflection ratio was 0.86 (20 mm downward from the center).