The major air conditioning task for aircraft is solving the various cooling problems that arise from high speed flight; that is, the dissipation of heat that is generated within and external to the aircraft.
External Heat Sources
From aerodynamic heating and heat received through solar radiation, even though a major portion of this heat is prevented from being transferred into the aircraft interior by the use of thermal insulation.
Internal Heat Sources
From heat generated within the aircraft by electronic, electrical, and mechanical equipment, and people.
It is vital that the temperature in the cabin is safe and comfortable for the crew and this temperature is obtained by VCCS and ACCS systems.
There are two main types of cooling systems in use today that can be used individually or combined.
- The air cycle system, which is based on the reduction of heat by the transformation of heat energy into work.
- The vapor cycle system in which the heat of vaporization is lost by evaporating a liquid refrigerant.