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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's since the water in your skin is evaporating. The air carries off the water vapor, and with it a number of the temperature has been recinded from your skin.

This really is similar to what are the results inside older refrigerators. Rather than water, though, the ice box uses chemicals to do the cooling.

You can find a few things that require to be known for refrigeration.

1. A gas cools on expansion.

2. If you have a few 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 Second Law of Thermodynamics.

Old Refrigerators

If you go through the back or bottom of an older fridge, you'll visit a long thin tube that curls back and forth. This tube is linked to a pump, that is powered by an electric motor.

Inside the tube is Freon, a type of gas. Freon may be the brand of the fuel. That fuel, chemically is called Chloro-Flouro-Carbon or CFC. This fuel was found to hurt the surroundings if it escapes from refrigerators. So now, other substances are utilized in a somewhat different approach (see next section below).

CFC begins as a fluid. The pump forces the CFC by way of a lot of coils in the freezer area. There the chemical turns to a vapor. When it does, it soaks up a number of the heat which may be in the freezer compartment. Since it does this, the coils get colder and the freezer begins to obtain colder.

In the part of your fridge, you will find fewer coils and a larger space. Therefore, less heat is absorbed by the circles and the CFC steam.

The pump then sucks the CFC as a vapor and pushes it through pipes which are on the outside of the fridge. By compressing it, the CFC turns back to a liquid and heat is given off and is absorbed by the air around it. That is why it might be a little warmer behind or under your refrigerator.

When the CFC passes through the surface circles, the fluid is preparing to return through the freezer and refrigerator over and over.

Today's Appliances

Modern appliances don't use CFC. As an alternative they use ammonia gas. Ammonia gas can become a liquid when it is cooled to -27 degrees Fahrenheit (-6.5 degrees Celsius).

A compressor and motor squeezes the ammonia gas. When it is compressed, a gas heats up as it is condensed. When you move the compressed gas through the coils on the back or bottom of a contemporary refrigerator, its heat can be lost by the hot ammonia gas to the air in the area.

Remember what the law states of thermodynamics.

Because it's under a higher pressure as it cools, the ammonia gas can transform into ammonia fluid.

The ammonia liquid flows through what is called an expansion valve, a little small opening that the liquid has to fit through. Between your valve and the compressor, there's a region because the compressor is taking the ammonia gas out of this area.

When the liquid ammonia gets a low pressure area it boils and changes in to a gas. This really is called vaporizing.

Where the colder ammonia in the coil pulls the warmth out of the spaces the coils then undergo the freezer and normal part of the freezer. This makes the interior of the freezer and whole fridge cold.

The cold ammonia gas is sucked up by the compressor, and the gas dates back through the exact same procedure over and over.

How Does the Temperature Stay the Same Inside?

A tool called a thermocouple (it's generally a can sense when the temperature in the icebox is as cold as you want it to be. When it reaches that temperature, the electricity is shut off by the device to the compressor.

But the refrigerator isn't completely sealed. There are places, like across the doors and where the pipes proceed through, a little bit can be leaked by that.

So when the cold from inside the refrigerator begins to flow out and the heat leaks in, the thermocouple turns the compressor back on to cool the refrigerator off again.

That's why you'll hear your fridge compressor engine coming on, running for a little while and then turning itself off.

Today's appliances, but, are very energy efficient. Ones offered today use about one-tenth the amount of electricity of ones that have been built two decades ago. Therefore, when you yourself have an old, old icebox, it's safer to obtain a new one because you'll spend less (and energy) over a long period of time.

To learn more 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 - Refrigerator (www.howstuffworks.com/refrigerator.htm)

Research Treasure Trove - ice box site (www.education.eth.net/acads/treasure_trove/refrigerator.htm)