Used in a range of industries, wet surface air coolers (WSACs) can be a cost-effective technology for both heat transfer and water conservation. Applications for these closed-loop evaporative coolers and condensers include fluid loop cooling, direct vapor condensing, hydrocarbon desuperheating and subcooling.

Niagara Blower, a Buffalo, N.Y.-based manufacturer of WSACs, says the technology offers several water-conservation benefits, including the ability to use poor-quality water as a makeup source; achievement of higher cycles of concentration; no exposure of process fluid to the environment; and the elimination of spray water contamination in the process stream.

Additionally, the use of WSACs may reduce the amount of water required in a plant due to the ability to use water previously discharged as spray makeup. Commonly used for adding capacity to thermally challenged plants, WSACs offer additional direct cooling without adding tower capacity or makeup water.

The basic principle of the technology is that heat is rejected by means of latent (evaporative) heat transfer. Warm process fluids or vapors are cooled in a closed-loop tube bundle. Open-loop water is sprayed and air is induced over the tube bundle resulting in the cooling effect. The process fluid being cooled never comes in contact with the environment.