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Heat transfer innovation garners Best Paper Award

Chung-Lung Chen standing behind Zhou Zhou at a desk with a computer.

Mechanical engineering Professor Chung-Lung Chen and recent graduate Zhou Zhou took first place for a paper on heat transfer at the American Society of Mechanical Engineer’s international conference in December 2013.

A paper submitted to an American Society of Mechanical Engineer’s international conference in December 2013 by MU Mechanical Engineering Professor Chung-Lung Chen and master’s student Zhou Zhou, received the conference’s Best Paper Award.

Selected from a field of 162 entries, “Flooded Two-Phase Flow Dynamics and Heat Transfer with Engineered Wettability on Microstructured Surfaces” took top honors at the 4th Micro/Nanoscale Heat & Mass Transfer International Conference in Hong Kong.

The award was especially meaningful to Chen, who came to MU from the private sector in 2011, because Zhou is his first graduate student.

“High power density electronics can create a lot of heat and if there is too much, they will not survive,” said Chen, explaining that one of the ways such devices are cooled is with liquids.

“You bring the cooling liquid as a thin film. With better liquid spreading and increased interfacial area, the two-phase thermal performance will be further improved,” Chen said.

The research reported in the paper examined replacing a flat cooling surface with one containing micro-pillar structures and engineered wettability to improve the heat dissipation rate.

“Generally, if you have higher bubble departure rate, you have better liquid-vapor heat transfer,” said Zhou.

Adding the pillar structures with two-tier wettability made the heat transport more rapidly and uniformly. Larger bubbles atop the micro-pillars with hydrophobic  — water resistant — surfaces absorbed smaller bubbles generated from the bottom surface, increasing the rate of heat dispersal.

The research included the use of varying structure geometries — arrangements and dimensions — with varying results. Tests demonstrated an approach to explore the optimal pillar height.

“No one did this before,” said Zhou, adding that although they found the combination of the pillar structures and wettability gradient increases cooling efficiency, there is room for improvement.

“We could try a more innovative structure besides square pillars,” Zhou added. “And we could try a different wettability pattern.”

Zhou, who received his master’s degree in December, wasn’t able to attend the conference but received the good news in a phone call.

“Dr. Chen called me from Hong Kong. He said, ‘All of the hard work was worthwhile.’ I have the same feeling,” Zhou said. “I’m grateful to him.”

Robert Tzou, the College of Engineering’s interim associate dean, is the founding chair of the ASME International Conference on Micro/Nanoscale Heat Transfer.