HI:
The thermodynamic properties of NH3(ammonia) are outstanding.When it breaks down it does so into its basic elements:N and H which are relativity safe.
Water(H2O) is the worlds best refrigerant as it can absorb the most BTU's before changing state, the trouble is its boiling point is higher than we would like.
The trade has given me a great base to my life's pyramid both financially and intellectually.You have to understand both chemical and electrical properties which includes their inherent dangers.