The water extracted from the Pack is used to:

The water extracted from the Pack is used to:

• A. Cool the cabin by spraying into the air
• B. Spray across the pack heat exchanger in the ram air duct
• C. Purge potable water
• D. Hydrate the flight crew

Answer: (B)

Evaporative cooling of the packs is what this is about. In the environmental control system, bleed air is cooled by passing it through the pack heat exchanger, and the ram air in the duct is used to reject that heat. Water extracted from the Pack is sprayed across the pack heat exchanger in the ram air duct so that as the ram air blows over a wetted surface, the water evaporates. This evaporation absorbs heat, making the heat exchanger more effective at lowering the temperature of the conditioned air before it goes to the cabin. It’s a targeted cooling enhancement inside the ram air duct, not a method to spray into the cabin, purge potable water, or hydrate the crew.

Evaporative cooling of the packs is what this is about. In the environmental control system, bleed air is cooled by passing it through the pack heat exchanger, and the ram air in the duct is used to reject that heat. Water extracted from the Pack is sprayed across the pack heat exchanger in the ram air duct so that as the ram air blows over a wetted surface, the water evaporates. This evaporation absorbs heat, making the heat exchanger more effective at lowering the temperature of the conditioned air before it goes to the cabin. It’s a targeted cooling enhancement inside the ram air duct, not a method to spray into the cabin, purge potable water, or hydrate the crew.