Why is it called a dry cooler?

A dry cooler is so called because it uses dry ambient air as the cooling medium to remove heat from the thermal fluid. Unlike water-cooled systems that use water as the heat transfer medium, dry coolers do not use any liquid or water in the cooling process, hence the term 'dry'.

In a dry cooler, the hot fluid flows through finned tubes and the surrounding air is drawn into these tubes by one or more fans. As the air flows through the tubes, it removes heat from the thermal fluid and the air is then discharged to the atmosphere. The term 'dry' is used to distinguish it from liquid cooling systems because no liquid is involved in the cooling process.

Dry cooling methods are often used in applications where water resources are scarce or expensive, or where the discharge of cooling water may be environmentally sensitive. In addition, under certain conditions dry cooling is more energy efficient than water cooling and is also more reliable because there is no risk of leaks or other water-related problems.