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In the summer, have you ever gotten out of a children's pool and then felt cold standing in the sun? That is as the water on your skin is evaporating. The air carries off the water vapor, and with it a few of the heat is being removed from your own skin.
This is much like what goes on inside older refrigerators. In place of water, though, the icebox uses chemicals to complete the cooling.
You will find two things that require to be known for refrigeration.
1. A fuel cools on expansion.
2. If you have two things that are different conditions that touch or are near one another, the hotter surface cools and the surface warms up. This is a law of physics called the Next Law of Thermodynamics.
Old Appliances
If you consider the back or bottom of an older fridge, you'll view a long thin tube that curls back and forth. This pipe is linked to a pump, that will be driven by a power motor.
In the tube is Freon, a kind of gas. Freon is the brand of the gas. That gas, chemically is called Chloro-Flouro-Carbon or CFC. This gas was found to hurt the environmental surroundings if it escapes from refrigerators. So now, other substances are used in a somewhat different process (see next section below).
CFC starts out as a liquid. The pump pushes the CFC by way of a lot of coils in the freezer area. There the chemical turns to a vapor. When it does, it eats up some of the heat that could be in the freezer compartment. Since it does this, the coils get colder and the freezer starts to get colder.
In the part of your fridge, you can find fewer rings and a more substantial space. So, less heat is soaked up by the rings and the CFC vapor.
The pump then sucks the CFC as a vapor and makes it through pipes which are on the beyond the fridge. By compressing it, the CFC turns back in a fluid and temperature is given off and is consumed by the air around it. That's why it may be just a little warmer behind or under your refrigerator.
After the CFC passes through the exterior rings, the liquid is ready to return back through the freezer and refrigerator over and over.
Today's Refrigerators
Contemporary appliances do not use CFC. Instead they use ammonia gas. Ammonia gas turns into a fluid when it's cooled to -27 degrees Fahrenheit (-6.5 degrees Celsius).
A compressor and motor squeezes the ammonia gas. When it is compressed, a gas gets hotter as it's pressurized. Once you go the compressed gas through the rings on the back or base of a modern fridge, its heat can be lost by the hot ammonia gas to the air in the room.
Remember the law of thermodynamics.
As it cools, the ammonia gas can change into ammonia liquid since it is under a higher pressure.
The ammonia liquid flows through what is called an expansion valve, a tiny small opening that the liquid has to fit through. Between your valve and the compressor, there's a region because the compressor is pulling the ammonia gas out of that area.
It boils and changes in to a gas when the liquid ammonia hits a low pressure region. This is called vaporizing.
Where the ammonia in the coil pulls the warmth out of the compartments the coils then proceed through the freezer and regular part of the refrigerator. This makes the within of the whole fridge cold and freezer.
The compressor sucks up the cold ammonia gas, and the gas goes back through the same process over and over.
How Can the Temperature Remain the Same Inside?
A device called a thermocouple (it's generally a can sense once the heat in the ice box is as cold as you need it to be. When it reaches that temperature, the system turns off the electricity to the compressor.
However the ice box isn't completely closed. You will find places, like across the doors and where in fact the pipes undergo, a little bit can be leaked by that.
When the cold from inside the refrigerator begins to leak out and the warmth leaks in, the compressor is turned by the thermocouple back to cool the refrigerator off again.
That is why you'll hear your ice box compressor engine coming on, running for a little while and then turning itself off.
Today's appliances, nevertheless, are extremely energy efficient. Ones offered today use about one-tenth the quantity of energy of ones that have been built twenty years ago. Therefore, when you yourself have an old, old refrigerator, it is easier to buy a new one since you'll spend less (and power) over a long time period.
For more information go to:
Argone National Laboratory - Ask A Scientist ( Hand's 8th Grade Science Site (www.mansfieldct.org/schools/mms/staff/hand/heatrefrig.htm)
How Stuff Works - Icebox (www.howstuffworks.com/refrigerator.htm)
Technology Treasure Trove - icebox site (www.education.eth.net/acads/treasure_trove/refrigerator.htm) inside appliance repair fairfax
