SSS 2011-11-16
时间:2011-12-02 06:02:39
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(单词翻译)
Ever wander through a supermarket and past the open refrigerated cases that house cream cheese, butter and OJ? The refrigerated shelves are protected by jets of air that blow across the front. These jets form an air shield to keep the warm air out.
Trouble is, it doesn't always work. The cases use extra energy to cool the air that leaks in. So researchers tested the ubiquitous cases. They shot air across the front to try out a variety of speeds, angles and other factors. They used a tracer gas to measure warm air
infiltration1.
And they found that the key players are the angle of the air
grills2 and what's called a Reynolds number—which involves the air jet's speed and
density3 and the jet's
turbulence4.
By adjusting these variables, they were able to get a ten percent reduction in warm air infiltration. Which the researchers say could save $100 million worth of electricity each year. The research was published in the journal
Applied5 Thermal6 Engineering.
The researchers have designed a system so that fridge case manufacturers can
optimize7 their companies' designs. And save us all some cold cash.
Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.
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