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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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1 infiltration
n.渗透；下渗；渗滤；入渗
参考例句：
The police tried to prevent infiltration by drug traffickers. 警方尽力阻止毒品走私分子的潜入。来自《简明英汉词典》 A loss in volume will occur if infiltration takes place. 如果发生了渗润作用，水量就会减少。来自辞典例句

2 grills
n.烤架( grill的名词复数 )；（一盘）烤肉；格板；烧烤餐馆v.烧烤( grill的第三人称单数 )；拷问，盘问
参考例句：
Backyard barbecue grills could be proscribed. 里弄烤肉店会被勒令停业的。来自辞典例句 Both side inlets have horizontal grills and incorporate impressive fog lamps. 两侧进气口的水平烤架并纳入令人印象深刻的雾灯。来自互联网

3 density
n.密集，密度，浓度
参考例句：
The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。 The region has a very high population density.该地区的人口密度很高。

4 turbulence
n.喧嚣，狂暴，骚乱，湍流
参考例句：
The turbulence caused the plane to turn over.空气的激流导致飞机翻转。 The world advances amidst turbulence.世界在动荡中前进。

5 applied
adj.应用的；v.应用，适用
参考例句：
She plans to take a course in applied linguistics.她打算学习应用语言学课程。 This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

6 thermal
adj.热的，由热造成的；保暖的
参考例句：
They will build another thermal power station.他们要另外建一座热能发电站。 Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

7 optimize
v.使优化 [=optimise]
参考例句：
We should optimize the composition of the Standing Committees.优化人大常委会组成人员的结构。 We should optimize our import mix and focus on bringing in advanced technology and key equipment.优化进口结构，着重引进先进技术和关键设备。