Ammonia Chilled Water System | Commercial HVAC
This chilled water unit is a new ammonia chiller. This unit is also unique in that it has no compressor. Instead it uses the chemical properties of ammonia and heat from natural gas to condense the refrigerant which is ammonia. A chiller provides chilled water to a chilled water loop. Cold water is circulated through a loop where it is direct into a coil in an air handler. Air is blown across a coil where a heat exchange process takes place. The air handler discharges cool conditioned air throughout a duct system. Chilled water systems are typically used in commercial air conditioning applicationsbut there are some chilled water systems in residential applications.
Ammonia Chilled Water System | Commercial HVAC | Conventional Systems
Most chilled water air conditioning system use compressors to compress the refrigerant so that it can be condensed in condenser coils. This systems uses natural gas and a heat exchanger to compress the refrigerant so that the condenser can condense the refrigerant in the system. The refrigeration process is the same it only uses a different means to compress the refrigerant. After the refrigerant is compressed it enters the condenser coils where heat is removed from the refrigerant. The refrigerant then goes to a metering device where it drops in pressure and temperature. It enters a chiller barrel where water flows. A heat exchange from the water to the refrigerant takes place and the water leaves the chiller barrel and is pumped towards the chilled water coil in the air handler.
Ammonia Chilled Water System | Commercial HVAC | Keeping the Food Cold
Ammonia refrigeration systems are used extensively in large cold storage warehouses for medium temperature to low temperature applications where deep freezing is necessary to freeze food products and other products that need to be frozen to keep is from spoiling or going bad. In the Western states of Idaho, Oregon, and Washington large cold storage warehouses are located near potato processing plants. The potatoes are processed at the plant and then sent to the ammonia cooled cold storage warehouse for flash freezing then stored until placed on a truck for transport to market. Many fast food companies get their french fries from these plants and Ammonia cooled cold storage warehouses located in the mentioned Western states. In the Midwest in states like Iowa, Nebraska, Colorado, and Texas (to name a few) large meat producers use ammonia cooled cold storage to cool the warehouses that store the meat such as beef and pork. The meat doesn’t stay in the warehouse long before it is loaded on a refrigerated truck and trucked to a grocery warehouse that may or may not be ammonia cooled cold storage. Large chicken processors such as Cargill and Tyson use ammonia cooled cold storage warehouses to store the chicken after it is processed and before it is placed on a truck and shipped to the market. Lots of food products are stored in ammonia cooled cold storage warehouses including produce, meat, and other food products that would otherwise spoil without cold storage.
Ammonia Chilled Water System | Commercial HVAC | Precautions
Ammonia refrigeration systems are great economical refrigeration systems for large scale cooling however, there are some side effects from using ammonia in refrigeration systems such as the ones described above in food cold storage applications. Ammonia refrigeration can be potentially dangerous and lethal if an ammonia leak occurs in the refrigeration system. Ammonia, if leaked out of the refrigeration system, will kill humans and can cause an explosion or fire of ignited. In many of the food cold storage warehouses mentioned above there are warning signs posted everywhere inside the warehouse along with an escape route if you hear the alarm and see the strobe sirens flash. Those technicians and engineers working around Ammonia refrigeration systems need to be aware that they need to wear personal protection equipment to protect them from the hazards of ammonia refrigeration. There is a specific category in OSHA regulations concerning Ammonia refrigeration systems and worker safety around Ammonia refrigeration systems. Additionally, if the Ammonia leaks in or near food products the food is contaminated and need to be disposed of to prevent poisoning. That includes contaminated food or the food packaging as Ammonia is highly toxic. Additional safety references to ammonia refrigeration can be found in NFPA 68 and the International Mechanical Code and other code books that relate to refrigeration and electricity in hazardous locations.
Ammonia Chilled Water System | Commercial HVAC | Hazards
Ammonia systems can be hazardous but the ammonia refrigeration systems have been used for many years to keep food products cold and safe from spoilage so these food products can be delivered safely to you the end consumer. The ammonia chiller above is installed for a building that will use it to cool a commercial kitchen. None of the ammonia refrigeration part of the chiller is inside the building so it is unlikely this chiller will be a hazard to the people in the building. The water runs into the chiller and is cooled and then runs into the building to a chilled water coil in an air handling unit. Hopefully, this chiller will provide cooling for the occupants of the building especially in the hot kitchen for many years to come.
Ammonia Chilled Water System | Commercial HVAC | Conclusion
The above chiller in the photo is odd in that it has no compressor and uses ammonia as a refrigerant. The vast majority of chillers utilize vapor compression refrigeration and the standard refrigeration cycle with a chemical refrigerant other than ammonia. The typical chiller has a compressor for the vapor compression refrigeration cycle. The above chiller uses the process of absorbtion to move the heat and it uses ammonia for the primary refrigerant.