A researcher鈥檚 guide to keeping batteries cool

by Joe Selmont, UAA College of Egineering  |   

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Getu Hailu, Ph.D., assistant professor of mechanical engineering at the UAA College of Engineering, and Martin Henke, a student in the mechanical engineering master鈥檚 degree program, are working together to determine a simple and efficient way of keeping the batteries cool. (Photo by James Evans, 熊猫在线视频)

As 熊猫在线视频ns we know how vital mobile devices are during a natural disaster. Anchorage鈥檚  November 2018 earthquake reinforced the importance of cell phones to place lifesaving calls to emergency responders, reach out to loved ones to ensure their safety and to access up-to-date information.

But what happens if the quake knocks out electricity? During an emergency situation like that, is there a failsafe in place that will help keep us all connected?

鈥淵es,鈥 answered Getu Hailu, Ph.D., assistant professor of mechanical engineering at the UAA College of Engineering. 鈥淓mergency backup batteries.鈥 

He added, 鈥淎fter Hurricane Katrina, which was an enormous disaster from many perspectives, including telecommunications, the Federal Communications Commission (FCC) put out a recommendation that telecom companies invest in battery facilities.鈥 

熊猫在线视频 companies have, by and large, followed that recommendation. At almost any cell tower across the state, you will find a small room with an array of large batteries that are constantly charging, sitting in wait for the moment in which they will be required to keep us safe. This is especially important in 熊猫在线视频, which is ranked 26th in the nation in terms of electrical grid reliability.

But these emergency backup batteries have one major drawback: they鈥檙e hot. And not just warm to the touch like your smartphone after it鈥檚 been plugged in for a few hours 鈥 but extremely hot. So hot, in fact, that 熊猫在线视频 telecom companies are spending hundreds of thousands of dollars per year to cool the batteries down.

Getu Hailu, Ph.D., assistant professor of mechanical engineering at the UAA College of Engineering, and Martin Henke, a student in the mechanical engineering master鈥檚 degree program, are working together to determine a simple and efficient way of keeping the batteries cool. (Photo by James Evans, 熊猫在线视频)
Hailu and Henke use fan affinity laws and computational fluid dynamics to model airflow that may extend battery life at cell phone towers across the state,which could offer life saving relief during a natural disaster, such as an earthquake, if eletrical grids were knocked out. (Photo by James Evans, 熊猫在线视频)

That鈥檚 where Hailu鈥檚 research comes in. With support from the ConocoPhillips Arctic Science and Engineering Endowment, Hailu and Martin Henke, a student in the mechanical engineering master鈥檚 degree program, are working together to determine a simple and efficient way of keeping the batteries cool. 

And their solution is, in fact, deceptively simple. They鈥檙e using air.

鈥淲ith fan affinity laws and computational fluid dynamics, we鈥檝e been able to model air flow and gain huge efficiencies with little adjustments,鈥 said Henke. 鈥淎nd the preliminary results are super encouraging. We could improve fan efficiency by up to 50%. This could really extend the functional life of those batteries.鈥

So, what is Henke talking about?

Basically, Hailu and Henke have spent a great deal of time on computer modeling to test a wide variety of air flow scenarios. To evaluate cooling efficiencies, the scenarios have been combined with the tried and true fan affinity laws that Henke mentioned. Like the law of gravity or the laws of thermodynamics, the fan affinity laws can be expressed through math and are based on repeated experiments.

鈥淲hat we鈥檙e focused on now is validating the computer model through experimental testing,鈥 said Hailu.

At the end of 2019, a team of mechanical engineering seniors designed and built an experimental unit that Hailu and Henke are now using to test their computer models. The experimental unit is a miniature version of the actual emergency backup battery facilities used by telecom companies. It is made of plexiglass, 9-volt batteries, a variety of electronic components, sensors and data acquisition devices.

For the time being, Hailu and Henke are running tests and waiting for more results. For Henke, who has made this research project the core of his master鈥檚 degree thesis, it has been a surprisingly fun experience. 

鈥淏efore really digging into this, I had to teach myself all about computational fluid dynamics,鈥 Henke said. 鈥淎nd with that knowledge I now get to help teach the heating, ventilation and air conditioning (HVAC) courses. I鈥檝e learned a lot.鈥 

Hailu and Henke鈥檚 research has applications outside of the telecom industry.

鈥淎lternative energy, big computing and the oil industries could all make use of this work,鈥 said Hailu. 鈥淚n fact, the oil companies are very interested. Their facilities 鈥 especially offshore facilities in hot places like the Caribbean 鈥 are constantly fighting overheated batteries. One of the seniors who helped design our experimental unit was just hired for exactly that reason.鈥

After graduation, Henke wants to take this project and continue leveraging it for meaningful purposes. He spent two years in the Peace Corps before coming back to UAA for his master鈥檚 degree and he wants to find a career that combines the ethos of the Peace Corps with the research experience he鈥檚 gained.

鈥淚 can see myself working in the alternative energy sector,鈥 said Henke. 鈥淭hat鈥檚 somewhere I can see making a difference.鈥

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