Industrial Refrigeration Service and Maintenance
The Past
Ammonia has been an established, pre-eminent industrial refrigerant for over 125 years. Ammonia is used in industrial refrigeration applications such as food production. CFCs, such as Freon, became popular in the 1930s due to their low toxicity. The chlorine in the refrigerant was found to have caused a hole in the ozone layer. Therefore, they have now been phased out. Non-chlorine, low toxicity, HFCs were developed to replace the CFCs
Now
Ammonia This is the best choice of refrigerant for industrial and many non-industrial applications
HFC These refrigerants have a high global warming potential, so they are being phased down to 21% by 2030
HFO Refrigerants, such as, R1234ze when they leak, go through the weather system and end up in the sea. They have been reported to be harmful to marine life. These refrigerants are used for chilled water and process applications
The Future
Ammonia will continue to be the best choice for large industrial applications. Between now and 2030 ammonia will also become increasingly popular in non-industrial applications, such as, the cooling of data centres and the air conditioning of buildings. Systems with a low refrigerant charge have been developed and rigorously field tested, so the application of cooling a small office with ammonia is becoming more and more common place. New ammonia chillers are simpler in design, therefore competitive in price to HFC chillers. The higher initial cost is paid back in electricity savings within 2 years- then they become cheaper. They use less electricity because ammonia has a latent heat bubble 5 times bigger than other refrigerants- more refrigeration effect and less gas
Industrial Refrigeration Compressors
A popular compressor type is the Screw compressor, right and below, which has two rotors running together. The Reciprocating compressor, in the above video, is another popular Ammonia compressor. NH3 compressors are open drive
Bearings and Rotors
Pipework used for Industrial Refrigeration
Ammonia corrodes various metals and alloys. Steel, however, works well with ammonia. The use of steel makes the maintenance different as opposed to HFC chillers. HFC chillers are prone to leaks on the copper pipework. On the condenser, the copper expands and contracts- eventually rubbing through against the steel frame. Vibration related leaks are also common. On an ammonia system, steel that is freezing then thawing on defrost or off cycles creates rapid rust formation and can lead to catastrophic failure of the pipework. Steel that is permanently frozen creates slower rust formation as the ice slows the oxidisation process. Our engineers carry out metallurgic testing to gauge the integrity of the steel
Toxicity
Ammonia systems are safe for non-industrial applications. The refrigerant is contained within the system. Similar to electricity being contained within plastic in your home. The low charge refrigeration plant shuts down in the event of a leak. You can stand next to a leaking ammonia system and tolerate the gas. The machine brings a fan on which disperses the small amount of ammonia into air. The ammonia then absorbs into the moisture in the air. One of our trained engineers will repair the leak start the machine back up
Residential Applications
Particularly in North Europe and to an increasing extent in the UK, ammonia is used in residential locations. An ice skating ring, for example, in Denmark is ammonia cooled using glycol as the secondary refrigerant. The system is water cooled with reciprocating compressors
Office Cooling
Cooling an office in a built up area is cheaper in energy savings compared with HFC. This covers the higher initial cost of investing in ammonia
Oil Harvesting
Oil used to lubricate the compressor and ammonia are non-miscible. That is to say: the refrigerant does not carry the oil round the system and back to the compressor. Oil return is achieved by various methods including eductors and an oil pot
Manual oil recovery
When there are oil return issues, the engineer has to work out where oil is not returning from and use his experience to resolve the issue. Otherwise, the machine will experience low oil return problems
Countdown for R404a Service Ban Above 10kg of Refrigerant
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