Farewell Freon…or maybe not. While conventional Freon refrigerants are being phased out due to environmental concerns, replacement technologies collectively known as the “new Freons” can play a valuable role in modern freezer and refrigeration applications.
There are horses for courses” advises an old saying, which basically means that “one size doesn’t necessarily fit all.” This principle applies to a range of situations, including the refrigerants used in industrial cooling applications. The food and beverage business has been dominated by ammonia as a refrigerant. However, Freon refrigeration has been an integral part of the industry since the early 20th century. While the last “true” Freon, R-22, will be phased out of the new equipment market next year, the replacement refrigerants approved by the U.S. Environmental Protection Agency (EPA) are recognized universally as Freons and still have a valuable role to play in the modern refrigeration industry.
Ammonia systems also carry other considerations. They require more regulation than Freon systems, and they require specially trained operators. Plants that have more than 10,000 lb of ammonia on site must have a process safety management (PSM) program. Additionally, some states severely restrict the application of ammonia systems. Government regulations with regard to PSM programs and Homeland Security issues also might affect a plant’s decision. Furthermore, if the plant is located in a crowded nonindustrial neighborhood, the owner might not be comfortable with the potential liability of an ammonia leak.
Freon can provide an alternative in both air-cooled and evaporative condenser systems. Small- to medium-sized Freon systems typically have a first-cost advantage. Additionally, split Freon systems - in which a single air-cooled condensing unit serves one or two evaporators with electric defrost on lower-temperature applications - might provide a refrigeration bridge to later expansion and possible conversion to ammonia.
In some food-handling applications such as the storage of nuts, Freon may ultimately be the best choice.
“There is a trend to lower the storage temperature of nuts to as low as 35°F (1.7°C) to extend the storage life. Even a small ammonia leak can turn the nuts black, rendering them unusable, “At higher temperatures, we were able to run a glycol chiller off of the ammonia system and use brine coils in the nut storage area. The lower temperature levels complicate the brine system as we struggle to adequately defrost these areas. The stand-alone Freon systems can easily accomplish this task with electrically defrosted coils.”
Narrowing the Gap
The low cost of ammonia refrigerant and the efficiency of ammonia refrigeration will keep these systems favorable from an energy standpoint for the foreseeable future. However, new and emerging Freon technologies might narrow the gap. For example, the introduction of semihermetic screw compressors and evaporative condensers in the water chiller business portends a day when a complete Freon skid with multiple semihermetic screw compressors and evaporative condensers in a “refrigeration house” might be set on a roof to serve a complete facility. Such a design might lower the refrigeration system’s energy footprint, provide hot gas coil defrost and use electronic expansion valves to take full advantage the lower head pressures available with the evaporative condensing. Packaging the systems together would lower field labor and provide more of a single-sourced solution while reducing mechanical room requirements.
While ammonia will always have a preeminent place in the industrial refrigeration market, “one size” never fits all. There are times and places where Freon systems make sense and might just be the right horse for the course.