Evaporative Cooling Systems: Principles

The principle behind evaporative cooling is that when water evaporates, it absorbs heat from its surrounding environment. As dry, hot air flows through a water-saturated cooling pad, the water undergoes a phase transition from a liquid to a gas (water vapor). This phase-change process directly extracts thermal energy from the air, resulting in a significant drop in air temperature—typically ranging from 10°F to 30°F (approximately 5°C to 15°C).

A complete evaporative cooling pad system primarily consists of four fundamental elements:

Cooling Pad (Media): Installed within the system’s side walls, these pads are typically constructed from specially treated cellulose paper or plastic materials. These materials are corrugated to form a robust, self-supporting structure with an exceptionally large surface area.
Water Distribution System: A water pump draws water from a reservoir tank and delivers it to a header pipe and distribution trough located at the top of the cooling pad. Driven by gravity, the water flows downward along the pad, ensuring that the entire surface of the cooling pad remains continuously saturated.
Axial Fans or Blowers:Positioned opposite the cooling pad, these units draw hot outdoor air inward, forcing it to flow through the moistened pad, and then blow the cooled air into the target space.
Water Reservoir and Float Valve:Used to collect the circulating water, the reservoir is equipped with a float valve that automatically maintains a specific water level.