Whether it’s a home refrigerator, air conditioner, or an industrial ammonia cooling system, refrigeration makes it all possible. It offers shelter from hot weather and cools our foods and beverages. However, did you know that refrigeration does not create cold air? In fact, it’s not possible to produce “cold.” What happens? Let’s look at some basics of refrigeration and see.
Early Cooling
For many years, man cooled things by placing them in ice or snow. In the early part of the 19th Century ice harvesting was big business, and before long, many people enjoyed the benefits of ice boxes. However, ice harvesting had limitations, and in 1758, a chemistry professor named John Hadley and Benjamin Franklin experimented with evaporation to cool things. Using alcohol and ether, they realized that evaporating gas removes heat.
The first ammonia cooling system appeared in 1820. Within a few decades, people had an ice machine that used a vapor compression system. By 1876, gas absorption refrigeration appeared.
Heat Removal
Refrigeration is possible because evaporating gas cools by removing heat. Stand in front of an electric fan with wet hair, and you’ll feel cool.
A typical refrigeration system uses a liquid like ammonia which has a low boiling point. A pump compresses the liquid, and it boils as it passes through evaporator coils. A fan blows through the coils and removes the heat. That’s why warm air comes out of your refrigerator and AC unit.
When gas goes through condenser coils, it condenses back into liquid. It then returns to the pump and the process repeats. In essence, a refrigeration system removes heat from a specified area. It cannot make cold air.
Modern Refrigeration
For years the ammonia cooling system was the standard for refrigeration. However, other refrigerants replaced ammonia for residential use. Yet, ammonia is still widely used in commercial applications because it is an effective refrigerant.