Closed Circuit Cooling Tower An indirect, or closed circuit cooling tower involves no direct contact of the air and the fluid, usually water or a glycol mixture, being cooled. Unlike the open cooling tower, the indirect cooling tower has two separate fluid circuits. One is the external circuit,which cools the closed Circuit tube bundles by spraying cold water over them.And the closed circuit tube bundles carry the hot process liquid to be cooled. In operation the heat flows from the internal fluid circuit, through the tube walls of the coils, to the external circuit and then by heating of the air and evaporation of some of the water, to the atmosphere. Operation of the indirect cooling towers is therefore very similar to the open cooling tower with one exception. The process fluid being cooled is contained in a "closed" circuit and is not directly exposed to the atmosphere or the recirculated external water. Square Cooling Tower Structure & Components Harrison cooling towers manufactures and exports highly efficient, durable cooling solutions tailored for a wide range of industrial applications. These cooling towers are designed with an advanced structure that requires minimal floor space, making them an ideal choice for facilities with limited room for equipment. One of the notable features of these FRP cooling towers is the three-pass exit system, which is engineered to significantly reduce drift losses and optimize the overall efficiency of the cooling process.