The refrigeration process works due to the physical process of evaporation in which a liquid (a refrigerant) absorbs heat from its environment as it evaporates. The amount of heat removed, and how efficiently it is done, depends on factors such as the compressor, evaporator, insulation, and in large part, the type of refrigerant used.
A Brief History of Refrigerants
The earliest chemical refrigerants commonly used were generally toxic and often dangerous.
Used primarily to create sulfuric acid, as a preservative, and as a laboratory reagent, in the environment, sulfur dioxide is a major air pollutant. Familiar from the smell of burnt matches, in larger amounts, long-term exposure, especially by those allergic to it, can have serious health consequences.
Methyl Chloride (R40)
Also known as chloromethane, methyl chloride is produced as part of some natural processes, but more commonly for industrial and commercial uses. Contributing substantial chlorine to air pollution, it is banned as a refrigerant but is still used in some chemical processes, including with some plastics and herbicides.
Ammonia is, of course, a common household and manufacturing chemical which is still used for industrial and commercial refrigeration, naval and marine applications, and even on the International Space Station. Unfortunately, its flammability and toxic nature limit its widespread use.
R12 and R22 -- Early Commercial Refrigerants
R12 (Freon-12, or dichlorodifluoromethane) and R22 (chlorodifluoromethane) were two of the first widely used hydrochlorofluorocarbon (HCFC) refrigerants, introduced in the 1930s and popular for being nonflammable and very stable. These HCFC refrigerants became so popular because they are generally only broken down by exposure to ultraviolet light. A great benefit to refrigeration technology, they were go-to compounds for refrigeration and air conditioning for decades.
Refrigerants and Environmental Concerns
The chemical nature of hydrochlorofluorocarbons and hydrofluorocarbons that makes them excellent candidates for refrigeration purposes is also their greatest drawback. Unfortunately in the 1970s and 1980s, it became clear that the chlorine in CFCs and HCFCs was critically damaging Earth's ozone layer and contributing to global warming by retaining additional heat in the Earth's atmosphere. In response, the Montreal Protocol of 1987 and subsequent agreements set a schedule to phase out these chlorine-based refrigerants. The Global Warming Potential (GWP) tool was developed to measure and compare the impact of refrigerants and other chemicals on the atmosphere and subsequent global warming. Rating refrigerants for their GWP values allows offending gases with high GWP values to be phased out and those with lower GWP values to be encouraged as substitutes. The system is based on carbon dioxide (CO2) which has a GWP value of 1, indicating the amount of heat 1 unit of CO2 would add to the atmosphere over a set amount of time (typically 100 years). Other chemicals and compounds are compared to CO2 over the same time period, so, for example, a compound with a GWP of 12 would heat the atmosphere 12 times as much as CO2 would over that 100-year period.
Refrigeration's Next Generation -- R134A and R404A
Arriving as plans were put in place to ban HCFCs for refrigeration needs, and specifically designed as a replacement for R12, R134A, also known as 1,1,1,2-Tetrafluoroethane or norflurane, is a hydrofluorocarbon compound that lacks chlorine, one of the most damaging compounds in HCFC refrigerants. With a GWP of 1,430, it's a definite improvement over R12 (GWP 10,200) and R22 (GWP 1,760). It rapidly became a popular substitute in refrigerators and vehicle air conditioners, as well as finding applications in manufacturing, pharmaceuticals, and a variety of consumer compressed air products. Developed around the same time as R134A, R404A (GWP 3,922) is a blended HFC mixture, widely adopted for use in commercial and industrial refrigeration, despite its relatively high GWP.
R290 and R600A -- Environmentally Friendly Refrigerants
Poor energy efficiency, high GWP values, and an increased concern for environmental impacts, including awareness that fluorines are nearly as damaging to the atmosphere as chlorines, has encouraged the development of new refrigerants. Striving for GWP values of zero, two hydrocarbon refrigerants have come to the forefront as effective, safe, relatively inexpensive compounds that can be used in many existing refrigeration systems with minimal modifications.
Stable and performing similarly to its predecessors, R600A is a massive improvement on environmental impacts with a very low GWP value of only 3. It has become one of the most popular refrigerants used today for domestic, commercial, and industrial refrigeration. Because it is flammable, it isn't necessarily suitable for retrofitting older refrigeration systems, but it's an excellent choice for systems designed specifically to use R600A, and is comparable to R12.
A combination of Isobutane and familiar, inexpensive, and readily available propane, isopropane (GWP 3) is becoming a standard refrigerant for use in commercial and industrial refrigeration as well as specialty applications for camping, recreational vehicles, and laboratory and medical refrigeration. In general, R290 is a good replacement for R22.
Benefits of Using Environmentally Friendly Refrigerants
Not only do these newer, hydrocarbon refrigerants have lower environmental impacts, they offer a variety of other benefits and savings.
Faster Temperature Recovery
Increased thermodynamic efficiency means that hydrocarbon refrigerants enable refrigerators and freezers to recover temperatures more quickly, making it easier to maintain crucial steady temperatures.
Lower Energy Consumption
Hydrocarbons provide cooling with nearly twice the efficiency of CFC refrigerants, and can perform well with a much lower charge than earlier, chemical refrigerants. These efficiencies allow for smaller compressors running with less power. All combined, these features can result in dramatically lower energy consumption.
Already extracted along with oil and readily available, hydrocarbons offer a relatively easily obtained replacement for less-desirable chemical refrigerants.
CFC-Free Refrigeration at American Biotech Supply
At American Biotech Supply, we believe in doing our part to care for the planet by using these CFC-free, low-GWP refrigerants which our EPA-SNAP-compliant refrigerator and freezer units are custom-designed to use. Savings in power consumption and the satisfaction of having equipment using environmentally friendly refrigerants, instead of some of the greatest contributors to global warming, should easily sway you to purchasing our CFC-free units. If not, our expertise, commitment to superior quality and customer satisfaction guarantee you refrigeration and freezer units to meet all of your cold storage needs. Contact us today to discuss your needs with one of our refrigeration specialists.