The Components Of A Fridge Freezer And How They Work
The basic science behind the fridge freezer has changed little over the past hundred years
. If you have ever wondered how your fridge freezer manages to keep your food cold and fresh then you will be surprised to learn that the technology which makes this happen is actually quite simple. Refrigeration is a process whereby heat is removed from a substance or enclosed space so that the temperature of that substance or space is lowered. This is achieved quite simply by evaporating a liquid and turning it into gas. When a liquid evaporates at a low temperature it draws heat energy from its surroundings and hence causes an overall temperature drop.
In order for a fridge to allow this process of evaporation to take place it needs to have some sort of closed loop cycle whereby the liquid can turn into gas and then back into liquid again, all the while taking in or emitting heat. You may have noticed that although the inside of your fridge is always cold the outside is always warm. This is because when the gas condenses back into a liquid again it produces excess heat.
There are five main components of a modern fridge. These are a compressor, an expansion valve, refrigerant, and heat exchanger pipes that are located both inside and out. The compressor is the component that heats up the gas and condenses it into a liquid. The coils at the back of your fridge let the gas release excess heat as this process takes place. The liquid then flows through the expansion valve and immediately evaporates. This lowers the overall temperature of the surrounding area. The cold gas is then sucked up through the compressor and the cycle begins again.
The refrigerants that have been tried and tested have changed numerous times over the years. Early fridge designs used toxic gases such as ammonia, sulphur dioxide and methyl chloride but sadly these led to a few fatal accidents as a result of leaks. Next was the introduction of CFCs, which were later found to be harming the Earths protective ozone layer. HFCs seemed to be an ideal replacement for CFCs but again these were found to be harmful to the Earths atmosphere because HFCs are a greenhouse gas and therefore contribute to the effects of climate change. Although some modern fridge freezers still use HFC refrigerant many have now turned to natural alternatives like propane and hydrocarbons. These now account for roughly 40 per cent of the global market.