Refrigeration refers to the process of removing heat from a place or substance and maintaining the cooler temperature over time. One example where this process takes place is in the refrigerator that is commonly present in every household. Those foods that have to be consumed later are stored in a refrigerator so that they do not go stale or rot, and remain as good as new whenever required. A refrigerator does not cool the objects present in it by lowering the temperatures. However, the heat gets drawn away due to the presence of an evaporating gas known as a refrigerant. This results in leaving the surroundings at a much lower temperature. You must have noticed that a refrigerator has two components.
On the top is the freezer where frozen items such as sausages, burgers, ice-creams and meat are kept. The food that is stored here is supposed to be at a freezing temperature. The compartment below does not provide freezing but simply refrigeration. Here those items are kept which are just required to be at cold temperatures, such as fruits, vegetables, juices and water. You must have heard the sound of a compressor working at one time or the other in your refrigerator. This is placed below and is a heavy metal device. Moreover, the pipes which exchange heat are behind the refrigerator. These can be seen if you slightly turn it around.
Ammonia, a powerful chemical makes the whole process of refrigeration work. This gas is compressed until it gets very hot and sent to the pipes where it is circulated. Ammonia is then cooled till it transforms into liquid, and forced inside through as expansion valve. While travelling through the freezer, the ammonia liquid that later turned into mist evaporates and takes in heat from the surroundings. This cycle keeps being repeated to keep the refrigeration working correctly.
At this writing, Astronautics Corporation of America in Milwaukee, Wisconsin is at the forefront of this field. Expect more technological breakthroughs as global warming headlines become more ominous. A group called Refrigerants, Naturally! formed early in this century by McDonald’s, and Unilever to develop and test HFC-free refrigeration technologies, making commitments to eliminate HFCs in their point-of-sale cooling applications. In 2007 Carlsberg, IKEA, and PepsiCo joined the group. How does the foodservice operator cope with the changes and the prospect of expensive new replacements for old workhorse refrigerators? Well, if your equipment is in good repair, you probably should do nothing as long as it lasts except keep it properly maintained.
This especially means cleaning the unit’s condensing coil once a month to prevent grease and dirt collection that block air circulation. If your refrigerator needs repair, you have two choices: Voluntarily retrofit it to use an alternative refrigerant, or purchase a new unit that is already equipped to use the newer refrigerants. Retrofitting almost always requires more than one service call and includes these steps: Recovering the outdated refrigerant, changing the coil in the compressor, replacing the filter or dryer, if necessary, recharging with the new refrigerant, checking performance for the first few weeks.
The EPA now has a sophisticated set of rules for refrigerator repair. The EPA certifies repair technicians and their equipment, and requires that they recycle or safely dispose of refrigerant by sending it to a licensed reclaimer. The rules also state that “substantial leaks…in equipment with a charge greater than 50 pounds” be repaired. This means if the unit leaks 35 percent or more of its pressure per year, it needs fixing. As the owner of commercial refrigeration equipment, you are also required to keep records of the quantity of refrigerant added during any servicing or maintenance procedure.
The EPA Web site contains summaries of the rules as well as lists of acceptable alternative refrigerants that don’t contain the ozone-depleting chlorofluorocarbons and hydrochlorofluorocarbons. They’re identified with abbreviations and numbers, such as MP-39, HP-80, R-406a, and GHG-X4, which probably don’t mean much to you as a foodservice employee. However, the important points to remember are: use an EPA-certified technician, with certified equipment, to do your refrigeration repair work. Underwriters Laboratories (UL) is now authorized to test and approve alternative refrigerants, so look for the UL label on products. Keep your maintenance records updated. Violations of the Clean Air Act can result in fines of up to $25,000 per day.
If you have more than one piece of older equipment, plan a gradual phase-out or retrofit program. Don’t break your budget by trying to do it all at once. This information should also serve as a caution when you are looking at purchasing used equipment. Is the owner getting rid of it because it no longer meets the environmental rules? With that, we’ve discussed the first major process going on inside the refrigerator: temperature reduction.