Closed loop indirect systems used for cooling and heating are a way to save energy and reduce carbon dioxide emissions. Evaporative (heat is rejected using the process of evaporation, water is consumed) and liquid-to-liquid are two types of closed-loop cooling systems where a transfer fluid has been used.
A closed-loop cooling system circulates coolant and rejects heat using heat exchangers in such a manner that the heat transfer fluid does not come into direct contact with the environment at any time. However, in the case of a poorly installed, damaged or aged system, fluid could leak unintentionally directly into the envirnoment. When selecting a heat transfer fluid for the use in a closed loop cooling systems, one should consider performance, sustainability ànd the potential environmental impact.