Glancing Back: Principally Principles

There is nothing mysterious about electric refrigeration. You know every “law” that governs its operations because you have seen these laws applied day after day. Let’s strip this of its technical terms and get down to ordinary language in talking it over.

First law: Heat always travels from the hotter to the colder objects. It operates like water running down a hill.

Consider a chunk of ice and a bowl of soup.

Put them in a refrigerator box and what happens? Why? The bowl of soup gets colder and the ice begins to melt. There you are! The heat in the soup is flowing through the air to the ice. This leads to the second law that you know all about.

Let’s see now; here’s your old chunk of ice, there’s your hot soup. Heat from soup heats the surrounding air. This travels to the ice and causes its melting. The heat then runs off in the water.

The soup, deprived of its heat, gets colder. Right here is the weakness in refrigeration by ice. Ice refrigerates only through its surface absorbing and the surface ice melting.…The smaller it gets, the less your refrigeration and the warmer grow the box and our plate of soup.

Second law: When a solid is turned into a liquid by the application of heat, this heat is absorbed.

When a liquid is turned into vapor (or, in other words, when it boils) by the application of heat, then again heat is absorbed.

The vapor will be turned back into the original liquid if the heat contained therein is taken away from it by cooling.

Now get a steel plate red-hot. Pour cold water on it. What happens? Why, the water is turned into steam and off it goes into the atmosphere.

But, in the turning of the water to steam, the heat is absorbed from the red-hot plate and, after a while, the plate gets cold because the heat has been used up and taken way when water turns to steam.

Third law: Different liquids have different temperature points at which they boil.

You heat alcohol and, at 173¿F, it boils. Ether boils at 94¿, but sulphur dioxide boils at 14¿. That is to say, when sulphur dioxide reaches 14¿, it begins to boil just as water boils at 212¿, and when it boils, it absorbs heat.

When methyl chloride reaches 10¿ below zero, it begins to boil and when it does, it gets busy absorbing heat units from anything warmer. So you can easily see why ether, sulphur dioxide, or methyl chloride refrigerates anything in a hurry. Imagine what happens to our plate of soup.

To celebrate The News’ 75th anniversary, “Glancing Back” ran throughout 2001. As the year draws to a close, so too does the series.

Publication date: 12/24/2001