What type of equipment cools by evaporation of water into an Airstream?

The correct answer is the evaporative cooler. This type of equipment utilizes the principle of evaporative cooling, where water is vaporized into the air. As the water evaporates, it absorbs heat from the surrounding air, effectively reducing the air temperature. This process is especially effective in low-humidity environments where the increased moisture content helps to cool the air that is circulated.

In contrast, a refrigeration unit or air conditioning system functions based on different principles that involve refrigerants circulating through coils and changing states (from liquid to gas and vice versa) to transfer heat. These systems rely on compressing and expanding refrigerants, rather than evaporation of water, to achieve cooling. A heat pump, while capable of providing both heating and cooling, also operates through the use of refrigerants and not through direct water evaporation. Thus, the unique mechanism of cooling through evaporation makes the evaporative cooler the correct answer.