Most people take their refrigerators for granted, except when they break down. While the main idea of how refrigerators work is fairly simple, how they are built is more complex. Chill out with this cool quiz to test your knowledge of how refrigerators work.
What is the core principle that makes refrigerators work?
Evaporating liquids absorb heat.
Raising pressure lowers temperature.
Turning liquids to solids decreases temperature.
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This principle also explains why water or alcohol feels cool on your skin, As they evaporate they absorb heat from your body.
What is special about the liquid inside your refrigerator's coils?
It evaporates at a low temperature.
It is inert and light.
It is almost impossible to freeze it into a solid.
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Because the refrigerant evaporates so easily, it is simple to change its form between liquid and gas. This is necessary so the liquid can cool the inside of the refrigerator.
It compresses the refrigerant to begin the cooling cycle.
It cools the refrigerant so it will absorb heat from inside the refrigerator.
It turns the refrigerant into a liquid.
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The compressor drives the system by compressing the refrigerant gas, which raises its pressure and temperature, so the heat-exchanging coils outside the fridge can cool it and turn it into a liquid, which evaporates in the coils inside the refrigerator and cools the contents.
The pressure in the outer coils is higher than in the inner coils of your refrigerator. The refrigerant has to pass through the expansion valve to get inside.
The boiling temperature of water at sea level is 212 degrees Fahrenheit, which equals 100 degrees Celsius. The Celsius scale is based on the freezing (zero Celsius) and boiling points of water.
Why does liquid nitrogen feel cold to humans even while it is boiling?
It has a very low boiling temperature.
It causes a chemical reaction in the skin.
It makes sweat evaporate from the skin.
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With a boiling point of -320 degrees Fahrenheit, liquid nitrogen is much colder while boiling than the 70 degrees Fahrenheit at which most humans feel comfortable.
the process through which the refrigerant is repeatedly heated and cooled
the process in which the temperature inside the refrigerator is reduced
the process of the compressor turning on every 15 minutes or so
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By keeping its refrigerant in a closed system, a refrigerator is able to raise and lower its temperature repeatedly. This way it can keep removing heat from the inside.
After the refrigerant leaves your refrigerator's compressor, where does it go next?
to the outer coils
to the expansion valve
to the inner coils
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Compressing the refrigerant raises its temperature. By moving through the outer coils, the refrigerant can give off its extra heat to the air outside, and not heat up the stuff inside your refrigerator.
What creates the low-pressure area in a refrigerator's inner coils?
the compressor sucking gas out of them
a lower temperature inside than outside the refrigerator
the expansion valve
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By sucking the refrigerant gas out of the inner coils, the compressor reduces the pressure inside them. This is why the refrigerant later flows back in from the higher pressure outside, through the expansion valve.
Why don't refrigerators use pure ammonia as a refrigerant?
high toxicity
too costly
high boiling point
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Inhaling pure ammonia gas is dangerous for humans. Were a refrigerator with pure ammonia refrigerant to develop a leak, it would be bad for anyone breathing in the fumes.
Why did people stop using CFCs as refrigerants in new refrigerators?
They are bad for the ozone layer.
They were discovered to actually be toxic, after all.
There was a shortage of one of the chemicals that is used to make them.
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Though the discovery that CFCs harm the ozone layer was made in the 1970s, it wasn't until the 1990s that manufacturers stopped putting them into new refrigerators.
