Frictional losses in duct sections are the result of air viscosity and the exchange of momentum between particles moving at different speeds. These losses can contribute to negligible losses or gains in air systems, unless the ducts have extremely long stretches or significant sections that use flexible ducting. The air resistance in the ventilation system is primarily determined by the air velocity in this system, which increases directly in proportion to air flow. This phenomenon is known as pressure loss.
The static pressure produced by a fan causes air to move in the ventilation system with a certain resistance, and the greater the ventilation resistance, the lower the fan airflow. The total pressure loss is equivalent to all pressure loss values in a ventilation system. There are two types of pressure loss in duct systems, namely, friction loss and dynamic loss. These losses are derived from different mechanisms and are therefore calculated using different methods.
Pressure loss between any two points in a duct system is measured at IWC. Pressure loss in the duct system can be reduced thanks to a larger duct section, which provides a relatively uniform air velocity throughout the system. In the air supply ducts of air conditioning systems, pressure losses in duct accessories, such as shock absorbers, sensors, curves, transition parts, duct corners, branches and even divider attenuators, are important to counteract the pressure difference created by fans. Therefore, accurately predicting pressure losses in duct fittings at the design stage is of vital importance for sizing ducts and selecting fans appropriately, which could ultimately generate great economic benefits in terms of initial investment cost and operating cost of duct systems. For this purpose, the diameters of the required air ducts and the pressure loss will be determined based on the admissible air velocity in the duct. When it comes to understanding pressure losses in ducts, it is important to consider both friction and dynamic losses.
Friction losses occur when air particles move at different speeds and exchange momentum between each other. This type of loss is usually negligible unless there are long stretches or sections that use flexible ducting. Dynamic losses occur when there is a difference between static pressure produced by a fan and air resistance in a ventilation system. This type of loss can be reduced by increasing the size of the duct section. In order to accurately predict pressure losses in duct fittings at the design stage, it is important to consider all factors that could affect them.
This includes factors such as shock absorbers, sensors, curves, transition parts, duct corners, branches and divider attenuators. By taking these factors into account when designing a ventilation system, it is possible to reduce initial investment costs and operating costs while ensuring optimal performance. Overall, understanding pressure losses in ducts is essential for designing efficient ventilation systems. By taking into account both friction and dynamic losses as well as all factors that could affect them, it is possible to reduce initial investment costs and operating costs while ensuring optimal performance.
