Pressure Drop in and Noise Radiation from Rectangular and Round Ducts - Literature Survey -

In this paper, a literature survey on rectangular and round ventilation ducts is presented. The comparison is based on two important aspects: pressure drop and noise radiation. The pressure losses in the ductwork should be kept as low as possible without jeopardizing proper control of the flow rates in the system. Pressure loss through a rectangular duct is significant higher than a volumetrically equal round one. The higher the aspect ratio, the higher-pressure loss in the rectangular system. Measurement data in the literature clearly show that the prediction error of friction factor always increases with increasing aspect ratio. Also, it is important to design a duct system that has low noise radiation since the sound propagating in a duct can break out with high enough amplitude in the residential areas to cause annoyance. It is concluded that when taking into consideration both the pressure drop in and the noise radiation from the ventilation system, round ducts generally perform better than rectangular ducts.