Experimental investigation of pressure losses at flexible air ducts with different structures

In this study, the experiments were conducted for the determination of pressure drop characteristics of the non-insulated aluminum-polyester laminated, non-insulated polyester laminated, pvc laminated and insulated aluminum-polyester laminated flexible air ducts under different bending conditions. The experimental setup is constructed according to the instructions in ANSI/ASHRAE standard 120?2008 and pressure loss data were measured based on the methodology in the same standard. The experimental data were processed using Power Law Model to form equations representing the pressure drop behavior of the flexible duct. The local loss coefficients were calculated using regression analysis for each bending condition. The results show that under stretched all the pressure loss values through the flexible duct with a diameter of 10 inch (254 mm) could be predicted via the empirical pressure loss equations derived using Power Law Model within an error less than ± 5 % in the range of volumetric flow rate of 700 and 2250 m3/h. In the same flow rate range, the measured values of pressure drop fall into the range of 1 and 85 Pa/m, and 1 and 130 Pa/m for bended cases. The local loss coefficient varies between 0.1 and 1.5 depending on the bending angle. Science Code : 914.1.002 Key Words : Flexible air duct, experimental study, pressure losses N