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In the summertime, perhaps you have gotten out of a swimming pool and then felt cold standing in sunlight? That's as the water in your skin is evaporating. The water vapor is carried off by the air, and with it a few of the heat is being recinded from your own skin.

This is similar to what are the results inside older appliances. As opposed to water, though, the fridge uses chemicals to complete the cooling.

There are two things that require to be known for refrigeration.

1. A fuel cools on expansion.

2. When you have two things that are different temperatures that touch or are near each other, the hotter surface cools and the cooler surface warms up. This is a law of physics called the Next Law of Thermodynamics.

Old Appliances

If you look at the back or base of an older ice box, you'll see a long thin tube that curls back and forth. This pipe is attached to a pump, which will be driven by a power motor.

Within the tube is Freon, a kind of gas. Freon may be the brand name of the fuel. This gas, chemically is called Chloro-Flouro-Carbon or CFC. This gas was found to hurt the surroundings when it leaks from appliances. So today, other substances are utilized in a somewhat different process (see next section below).

CFC starts as a liquid. The pump forces the CFC by way of a lot of rings in the freezer area. There the chemical turns to a vapor. When it does, it eats up a few of the temperature that could be in the freezer compartment. Because it does this, the coils get colder and the freezer begins to have colder.

In the part of your fridge, you will find fewer coils and a bigger room. Therefore, less heat is absorbed by the rings and the CFC vapor.

The pump then sucks the CFC as a steam and makes it through pipes which are on the outside the refrigerator. By compressing it, the CFC turns back in a liquid and heat is given off and is consumed by the air around it. That's why it might be only a little warmer behind or under your refrigerator.

When the CFC passes through the surface coils, the fluid is able to go back through the freezer and ice box over and over.

Today's Appliances

Modern appliances do not use CFC. Instead they use ammonia gas. Ammonia gas can become a fluid if it is cooled to -27 degrees Fahrenheit (-6.5 degrees Celsius).

A motor and compressor pushes the ammonia gas. When it's compressed, a gas gets hot as it's condensed. Once you move the compressed gas through the coils on the back or bottom of today's ice box, the hot ammonia gas may lose its heat to the air in the room.

Remember what the law states of thermodynamics.

Since it's under a top pressure as it cools, the ammonia gas can change into ammonia fluid.

The ammonia liquid flows through what is called an expansion valve, a little small hole that the liquid needs to fit through. Involving the valve and the compressor, there's a area since the compressor is taking the ammonia gas out of this part.

If the liquid ammonia gets a low pressure area it boils and changes right into a gas. This is called vaporizing.

Where the cooler ammonia in the coil pulls the heat out of the chambers the circles then undergo the freezer and regular part of the freezer. This makes the within of the fridge and whole refrigerator cold.

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

So How Exactly Does the Heat Remain the Same Inside?

A computer device called a thermocouple (it's basically a can sense if the heat in the refrigerator is as cool as you want it to be. When it reaches that temperature, the electricity is shut off by the device to the compressor.

But the icebox is not completely closed. You will find places, like round the doors and where in actuality the pipes undergo, a little bit can be leaked by that.

So when the cold from inside the refrigerator begins to leak out and the heat leaks in, the compressor is turned by the thermocouple back to cool the refrigerator off again.

That's why you'll hear your refrigerator compressor engine coming on, working for a time and then turning itself off.

Today's refrigerators, however, have become energy efficient. Ones sold today use about one-tenth the quantity of energy of ones which were built two decades ago. Therefore, if you have an old, old icebox, it is better to obtain a new one since you'll save money (and power) over an extended time frame.

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 - Fridge (www.howstuffworks.com/refrigerator.htm)

Technology Treasure Trove - refrigerator page (www.education.eth.net/acads/treasure_trove/refrigerator.htm)