What is utilized to cool the supply air during flight?

The cooling of supply air during flight is achieved by utilizing ram air from outside the aircraft. Ram air is the ambient air that flows into the aircraft as it moves through the atmosphere at speed. This airflow can be directed into specific cooling systems to lower the temperature of the supply air before it enters the cabin or other critical systems.

Using ram air is an efficient method because it leverages the natural airflow without the need for additional mechanical systems or energy sources. This method is particularly effective in flight since higher speeds lead to greater airflow, enhancing the cooling effect. It ensures that the supply air is at a comfortable and safe temperature for the crew and passengers, as well as maintaining optimal operating conditions for onboard equipment.

While options like compressed air from the engine or hydraulic coolant fluid might have their own uses in other contexts, they are not typically employed for cooling the supply air during flight. Recycled cabin air is often used for ventilation and maintaining air quality but does not serve as a primary source for cooling supply air.