Which of the following describes the role of the turbine in an air cycle system regarding air temperature?

• A. It causes the air to drop in temperature, producing cold air for air conditioning
• B. It heats the air to increase pressure
• C. It filters the air to remove particulates
• D. It adds humidity

Answer: (A)

The turbine’s function in an air cycle system is to lower the air’s temperature during expansion. After the air is compressed and cooled, it expands through the turbine, which uses the air’s energy to do work on the turbine blades. This energy transfer causes the air to cool as it expands, producing the cold air used for cabin environmental control. The turbine isn’t there to heat air, filter particulates, or add humidity—the cooling during expansion is the key effect that makes the air conditioning possible.