It is to minimize frictional losses and ensure that the duct is easy to install. A duct with a higher aspect ratio will have more surface area, which will increase the frictional losses.

Round ducts are stronger than rectangular ducts of the same cross-sectional area, which makes them less likely to collapse under pressure. They are also more flexible, which makes them easier to install in tight spaces. Round ducts are also more efficient than rectangular ducts, as they have less surface area, which reduces frictional losses.

Friction loss is the energy that is lost in friction as air flows through the duct. Dynamic loss is the energy that is lost as air flows through the duct due to turbulence or changes in size, shape, direction, or volume flow rate in a duct system.

By removing the latent heat, the air is cooled, causing water vapor in the air to condense into liquid water. This condensed moisture is typically collected and drained away, resulting in a decrease in both the humidity and temperature of the air.

Fans in series are seldom used for ventilation purposes. This is because series fans create more airflow resistance, which can reduce the amount of air that is circulated. This can lead to poor ventilation and uncomfortable temperatures.

If the discharge pressure of an air conditioning system is too high it can be because of higher outdoor temperatures or because of refrigerant not flowing properly through the system. This results in more work on the compressor to pump the refrigerant through the system thereby increasing the compression ratio (ratio of the highest pressure in the system to the lowest pressure in the system).

controlling combination of temperature, relative humidity and air movement

When the distance between the diffuser and the occupied zone is relatively short, jet nozzles can effectively direct the airflow without significant loss of momentum or diffusion.

The aluminum fins in an air conditioning system are coated to reduce the surface tension of the condensate water droplets thereby helping the air conditioning system to remove more heat from the air

By adjusting the position of the face dampers and bypass dampers, the amount of moisture removed/added to the air can be controlled.

This is because the fan (runs at the same speed) is set to deliver a constant volume of air regardless of the load.

HEPA stands for High-Efficiency Particulate Arrestance. HEPA filters are designed to remove 99.97% of airborne particles that are 0.3 microns or larger. This makes them ideal for use in clean rooms

In abrupt expansion in the duct, air expands suddenly which results in loss of kinetic energy and this energy is converted into pressure drop. On the other hand, when the air contracts suddenly, it gains kinetic energy and this energy is used to overcome the pressure drop.

Aluminum is a popular material for ductwork because it is lightweight, strong, corrosion-resistant and relatively inexpensive