In the gas cycle system, we never have a vapor in one side and a liquid in the other. Cooling is achieved by expanding and compressing the refrigerant vapor. This method is used in a device some of us may have in our homes called a “heat pump.” It is an efficient way to do cooling when you don’t need to reach freezing temperatures. When is this useful? When you’re air conditioning a house!

There are now small, portable coolers that use thermoelectric cooling, or the Peltier Effect. In the Peltier Effect, when certain solid state materials are placed together and an electric current is run through them, a reaction starts which results in a transfer of energy. The end result is an electronic device that produces cooling.

A new method, being studied in the laboratory but not ready for commercial application, is called Magnetic Refrigeration. There is even a way to use sound waves in a pressurized gas to produce heat transfer. This is called Thermoacoustic Refrigeration.

The Cold, Hard Facts

     •  Celsius (formerly known as Centigrade) – A temperature measurement scale where 0º C is the freezing point of water and 100º C is the boiling point. The scale was invented by the Swedish astronomer Anders Celsius around 1742.

     •  Fahrenheit – A temperature measurement scale where 32º F is the freezing point of water and 212º F is the boiling point. The scale was invented by the German Physicist, Daniel Gabriel Fahrenheit. No one knows exactly why he came up with this scale. There are many theories, though!

     •  Kelvin – A temperature scale where 0 K, also called absolute zero, is where all thermal energy ceases. The scale was invented by the Irish physicist, William Thompson, the First Baron of Kelvin. It is also referred to as a thermodynamic scale. Each degree Kelvin is one degree Celsius.

     •  Rankine – A temperature scale where 0º R is absolute zero (just like the Kelvin scale), but each degree Rankine is one degree Fahrenheit. It was invented by the Scottish physicist William John Macquorn Rankine. 

Ray and Gale Lawson have been homeschooling their three children since 1995. Ray holds a B.S. in Electrical Engineering from the Virginia Military Institute and works for Washington Safety Management Solutions, LLC. Gale holds a B.S. in Mechanical Engineering from the University of South Carolina and is a full-time mom and teacher. They are members of Breezy Hill Baptist Church in Graniteville, SC. Questions, comments and suggestions are always welcomed and can be emailed to them at (Gale).

This article was originally published in the May/June 2008 issue of Home School Enrichment Magazine. Visit to request a FREE sample issue today!