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2009-11-28 03:36:33 - Klaas Visser

As an ammonia application engineer with more than 40 years I have been advocating using NH3 for building cooling long before it happened. However, now something better has come along viz. Carbon Dioxide, something I worked with 50 years ago on board a ship. It is easy to pump carbon dioxide around a building at evaporating temperatures 10 to 14 deg C, rather than large chilled water pipes. In the london climate air cooling would be possible virtually all year round, with perhaps a little adiabatic assistance in hot weather.
Coupled with economising cycles, chilled beams or floor level air distribation, energy recovery from exhaust air-streams and proper duct sizing, energy savings in excess of 70% compared to conventional HCFC/HFC systems when applied in the relatively hot climate of Sydney Australia. A part of this energy inprovement is that when running part of the CO2 plant in transcritical mode, all heat required in the building for sanitary hot water, building heating, AC reheating etc. may be rcovered from the transcritical CO2 compressor discharge with a gliding temperature. This obviates a gas fired boiler and associated infrastructure in the building!!

When applying ammonia refrgeration to AC water chilling sets we are essentially addressing only one issue and that is using a natural refrigerant instead of a chemical refrigerant, thereby getting rid of high global warming impact. But the rest of the system is basically the same with high parasitic loads from suply, return air and exhast fans, chilled and cooling water pumps, cooling tower fans and the like, the overall energy efficiency of Ammonia refigerated chilled water supplying an otherwise little changed AC cooling system configuration is not going to be the paradigm shift required to achieve much inproved energy efficiencies in the built environment. London already has a high profile Ammonia chilled water- cooling tower water cooled condensing system at Terminal 5, which I am very pleased about. But when attending the first IIR Gustav Lorentzen Natural Refrigerants Conference in Hanover in May 1994, we saw in that city two ammonia plants applied to building cooling. One was a conventinal AC system with PHX condensers supplied with cooling tower cooled cooling water serving the Hanover Messe (Exhibition Centre) and the other was an ammonia refrigerated chilled water plant in the basement of a bank building in he Hanover CBD with roof mounted air cooled condensing. So ammonia cooling of beildings is hardly anything new.

So, in conclusion I submit that another ammonia refrigerated chilled
water system at the very high profile London Olympic Games in 2012 would be much better than an HFC refrigerated chilled water system, there are many other issues to be addressed to reduce he energy consumption of heating and cooling in the built environment.

Carbon Dioxide is the only natural refrigerant to do this, because it has all the desirable charcteristics and properties to deliver the paradigm shift in reducing the energy consumption in the built environment by at least 70% and very likely more. Please remember that it was quite common to use CO2 for the cooling only of buildings up to the mid 1930's after which the use of CO2 declined with he invention of CFC's in the early 1930's. But in 1987, 50 years later, the Montreal Protocol called for the rapid phase out - and subsequent banning - of CFC's because of the OZONE depleting properties of particularly CFC's. HCFC's were also to be phased out and banned over a longer time frame by the Montreal Protocol in 1987. But 60 % of all R22 ever produced was produced from 1989 onwards, two years after the Montreal Protocol called for it to be phased out. And 80% of the R22 ever produced is in the atmosphere adding about 15 billion tonnes of permanent green house gas and still increasing every day!!! It is an old saying, that people only learn from their own mistakes. My variation on that is one only knows one has done it wrong AFTER one has done it. But I am starting to wonder the veracity of that old wisdom considering what happened with R22 and before that with DDT, PCB's, Agent Orange etc..

Are we going to repeat the same mistake with HFC's replacing HCFC's, thereby getting rid of a small ammount of ODP in R22 for an increase in Global Warming? Just like a great part of the boom in high GWP/low ODP R22 (HCFC) consumption was caused by replacing CFC's, which have both high ODP/high GWP! Absolute lunacy it you ask me!

Please consider carbon dioxide to supply both heating and cooling at the London Olympics! Contrary to what some "experts" might say, all the technology and application know-how required is available today. All I am suggesting is to replace the ammomia compressors with CO2 compressors, ideally - but nt necesarilly - the chilled water system with much lower cost pumped direct evaporating CO2 system and replacing the boiler with a CO2 heat pump system, of which 5 million or so are being used in Japan (Ecocute) for domestic water heating and increasingly so in hotels, hospitals etc.. The use of CO2 heat pumps for water and space heating is growing rapidly in Europe and China! If anyone reading, believes and agrees with this and knows and/or has acces to the mayor of London, please give him a copy of this! The worst that can happen is that he informs the Australian authorities that here is a dangerous lunatic on the loose in Kangaroo Flat, Victoria, Australia! I wonder whether it would be MI5 or MI6 delivering such bad news to Her Majesty's Australian Govenment.

With best wishes and kind regards

Yours sincerely

Klaas Visser.