Ammonia as a refrigerant

September 2013

Prior to 1850, a brilliant Australian Engineer, James Harrison invented the vapour compression refrigeration system by “closing the loop”. He was aware that when ether evaporated it made printing type set cold when used for cleaning. His invention collected the evaporated gas, compressed it, condensed it and fed it back as a liquid to be re-evaporated, thereby forming a closed loop. Refrigeration was born. By 1855, Harrison was manufacturing  ice machines operating on ether in the closed refrigeration circuit, while the rest of the world were still cutting ice blocks from frozen rivers and lakes. In 1856, Harrison was awarded patent No. 747 for his invention.

In the 1860’s, ammonia started to be used in refrigeration as it was seen as a much safer alternative than ether.  Ammonia quickly gained popularity and by 1900 it dominated the world of refrigeration as the refrigerant of choice. The ammonia domination remained through until the 1930’s when the first synthetic refrigerants known as CFC’s were introduced.  CFC’s and subsequently HCFC’s and HFC’s then took over and dominated the commercial, domestic and transport refrigeration and air conditioning sectors, confining ammonia to the Industrial refrigeration world. Recent decades have seen the phasing out of the synthetic refrigerants in recognition of their extreme environmental damage.  There has been a resurgence of the use of ammonia as one of three naturally occurring refrigerants attracting huge support worldwide, the other two being carbon dioxide and hydrocarbons.

From a thermal engineering point of view, ammonia is an excellent refrigerant achieving vapour compression, cycle efficiencies better than virtually all other refrigerants.

In a refrigeration system, the refrigerant is a working fluid which circulates around a closed loop, carrying heat from one location to another. The refrigerant is not consumed, and only needs topping up if some leaks out. Therefore the consumption of anhydrous ammonia for refrigeration purposes is only a tiny fraction of the amount of ammonia manufactured each year. The amount would be in the order of a fraction of one per cent. The total amount of ammonia manufactured worldwide each year is in excess of one hundred million  tonnes, whilst that used in refrigeration would be in the order of tens of thousands of tonnes.

The world has been using ammonia as a refrigerant for 150 years; it has proven itself as a star performer from an efficiency, environmental and safety point of view. For these reasons, it can do nothing but grow in popularity into the future.

In the next instalment we will discuss the profound impact ammonia has on the world as a fertilizer

Until then, Kind Regards


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