UMD engineers to test boiling at zero-gravity

Feb 25, 2011 By Missy Corley
UMD engineers to test boiling at zero-gravity
Team members on the European Space Agency A300 aircraft in April 2010. From left to right: Jungho Kim, Paolo DiMarco (professor, University of Pisa), Rishi Raj (graduate student), and Serguei Dessiatoun (research professor, U-Md.).

Here on Earth, the process of boiling is used for tasks ranging from cooking and heating to power generation. In space exploration, boiling may also be used for power generation and other applications, but because boiling works differently in a zero-gravity environment, it is difficult to design hardware that will not overheat or cause other problems.

University of Maryland Professor Jungho Kim of the A. James Clark School's Department of Mechanical Engineering is working with John McQuillen, project scientist at NASA's Glenn Research Center in Ohio, to study how is altered in zero-gravity.

Their experiment, the Microheater Array Boiling Experiment (MABE), will launch on the Shuttle Discovery on February 24 and be placed aboard the for operation in the following few months. The experiment, which has already been tested on NASA's "Vomit Comet" and the European Space Agency's Parabolic Flight Campaign in France, will be installed in the Microgravity Science Glovebox once aboard the ISS.

The results of the experiment could help engineers design space hardware that uses boiling for multiple applications.

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"In space, boiling may be required to generate vapor to power turbines in some advanced concepts for power generation, for temperature control aboard spacecraft, and for ," says Kim.

When a liquid is boiled on Earth, vapor, which is less dense than liquid, is removed from heated surfaces through the action of buoyancy. In zero-gravity, the buoyancy force becomes negligible and vapor can blanket the heated surfaces rather than moving away, potentially leading the surfaces to a state known as critical heat flux.

Critical heat flux occurs when a heater or plate becomes too hot, restricting the flow of liquid to the surface and causing the plate to overheat and potentially burn out. Since liquids boil differently in space, an understanding of how these fluids behave can improve the reliability and expand the applications of space exploration hardware.

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Video demonstrating the boiling experiment

The experiment that will take place on the ISS will use two arrays of platinum microheaters bonded to a quartz plate. The arrays measure 7 mm and 2.7 mm across. The heaters are warmed when electricity is applied, and spaces between the heaters lines will allow the boiling process to be visualized through the transparent quartz. Boiling of a refrigerant-like fluid (FC-72) will be filmed at high speed and the video sent back to Earth along with the heater data in real-time for analysis.

"We have calibrated these heaters as a function of a temperature, and we measure the power level required to keep each of the heaters in the array at a constant temperature" Kim states. "Using a camera that looks through these microheaters, we can examine the relationship between the power level and the state of the fluid above that microheater."

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User comments : 7

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hush1
not rated yet Feb 26, 2011
Water matters.
:)
Doug_Huffman
not rated yet Feb 26, 2011
Really? I don't think so.

Tong's Boiling Crisis and Critical Heat Flux (AEC, WEC) was written in 1972 and has scaled and endured quite well since. It doesn't even have an index entry for water.

An amusing observations is that the adjacent "Relevant PhysicsForums posts" aren't. They're not even close, being entirely cribbed from "General Astronomy."
hush1
not rated yet Feb 27, 2011
Really? I don't think so.

It doesn't even have an index entry for water.


Taking the words of Prof. J. Kim, (taken from the you-tube clip), at face value:

"...all the water that is on the spacecraft, need [sic]to be recycled, and that will also require phase change heat or boiling processes."

Obviously, I am being misled.
Now all I can express is that the in situ testing meets all, or reveals even more than, the expectations of all the researchers involved.

It is difficult to say why I am so uncritical of Physorgdotcom shortcomings. I see many daily critical remarks about the Website. To speculate why Physorgdotcom is so inattentive towards criticism is just that: speculative.

The word 'spin' obviously underwent a change in meaning unimaginable just a decade ago.

kaasinees
1 / 5 (1) Feb 27, 2011
Water could be purified with ozon or UV radiation... or even using strong magnetic fields. Boiling on a spacecraft is really dumb and inefficient...
hush1
not rated yet Feb 27, 2011
Yes. I agree. Exposing contaminated water to UV radiation creates the O 3 radicals needed to reduce any organic contaminates to a fine white ash. Channel the UV radiation from space itself. Exactly where, ironically, the greatest effort is taken to minimize exposure to UV radiation to astro-/and cosmonauts, maximize the exposure.
GSwift7
1 / 5 (1) Mar 01, 2011
Forget the water purification nonsense. They have solutions to that problem that don't involve boiling. Think about the really important things that rely on gas bubbles in fluids and boiling, like making beer and distilling alcohol. If 'man' is to survive in space we need to at least have the basic needs figured out. Has anyone even tried to figure out how a carbonated beverage behaves in microgravity? OMG!

Seriously, all kidding aside: The process of distillation is an important industrial and scientific process. We need to have a good understanding of the limitations and advantages of doing these processes in microgravity so that we can design efficient space-born processes for basic industrial and scientific needs. Sometimes even the most basic lab procedure won't work without gravity. You have to re-think everything.
GSwift7
1 / 5 (1) Mar 01, 2011
On further thought, I suppose that if you really wanted to set up a still in micro g you could probably rig one of the centrifuges to allow normal boiling action. Whew, I was starting to worry that mankind might not make it to space after all. That's a relief. Do you think dominos delivers in that zip code? Hmmm, another problem.

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