Low-charge ammonia systems are refrigeration plants that use natural, environmentally-friendly ammonia refrigerant in low volumes, as an alternative to existing hydro-fluorocarbons (HFCs). Along with the important environmental benefits of using ammonia in lieu of HFCs, low-charge ammonia technology can also provide performance improvements as well as lower ammonia inventory for reduced risk in the event of a leak.
In 2016, a historic agreement was made between 197 countries to limit the use of greenhouse gases and phase out HFCs worldwide. Known as the Kigali Amendment, this important change to the Montreal Protocol paved the way for a new era of industrial refrigeration by phasing down the environmentally unfriendly HFCs).
Ammonia is a compound of nitrogen and hydrogen commonly used as a refrigerant. The 'low-charge' part of the term refers to how only a small amount of ammonia is contained in the refrigeration process, limiting the risks associated with a large volume release of ammonia in the event of a leak.
When designing an industrial refrigeration system, it’s important to consider the amount of ammonia that will be needed to ensure effective and reliable operation. A range of technologies can be used to reduce the amount of ammonia in circulation whilst maintaining the overall efficiency of the refrigeration system.
These systems are cleaner and greener than those HFC systems they are designed to replace.
The use of low-charge ammonia also enables a significant reduction to operating costs, with 15-30% lower annual energy consumption compared to traditional HFC technologies.
Many of these savings are thanks to reduced power consumption.
Installation and maintenance costs are reduced, with low-charge ammonia requiring 30-50 times lower inventory in warehouse air coolers, along with a 3-5 times overall inventory reduction on their standard
Low-charge ammonia has a wide range of uses within industrial refrigeration. There are five common types of low-charge packaged systems currently in use, each of which offers distinct benefits depending on the application.
Low-charge ammonia can be used in air conditioning applications, chemical processing plants, meat processing plants, food production facilities, cold storage facilities, and HFC replacement systems.
Recirculated systems utilise a central refrigeration machine together with pumps to recirculate cooled liquid.
Direct expansion systems take advantage of the pressure differential between compressors to move liquid from the machine room to the evaporators
Cascade systems which conjoin two central systems to provide efficient cooling to the evaporators.
Distributed systems use multiple localised systems which work together to improve efficiency.
Secondary systems cool and pump a secondary coolant, with the ammonia or carbon dioxide remaining in the machine room at all times.