College of Engineering Mechanical Engineering Birck Nanotechnology Center Energy Center
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About the PI:

Professor Ruan received his B.S. and M.S. in Engineering Thermophysics from Tsinghua University in 2000 and 2002, respectively. He received an M.S. in Electrical Engineering and Ph.D. in Mechanical Engineering from the University of Michigan at Ann Arbor, in 2006 and 2007 respectively. He then joined Purdue as an assistant professor. He was promoted to associate professor with tenure in 2013 and to full professor in 2017. Dr. Ruan received several awards, including the NSF CAREER Award in 2012, the ASME Heat Transfer Division Best Paper Award in 2015, the College of Engineering Early Career Research Excellence Award in 2016, the School of Mechanical Engineering Outstanding Graduate Student Mentor Award in 2016, the B.F.S. Schaefer Award in 2017, and was named a University Faculty Scholar in 2017. He was an Air Force Summer Faculty Fellow at the Wright Patterson Air Force Base at Dayton, Ohio in 2010, 2011, and 2013. He currently serves as an associate editor for ASME Journal of Heat Transfer, and an Editorial Board Member for Scientific Reports, a journal published by the Nature Publishing Group. [CV]


Office: ME 2153 and BNC 1270     Phone: 765-494-5721 (ME), 765-494-6603 (BNC), Fax: 765-494-0539    

e-mail: ruan@purdue.edu

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Positions open: We may have positions for postdoc fellows, graduate students, and undergraduate students. Please check here.


11/2018: Invited talk. Dr. Ruan gave an invited talk at ASME IMECE.


10/2018: Student award. Xiangyu received the third-place Best Poster Award at the 2018 CTRC Fall Meeting. Congratulations to Xiangyu!


09/2018: M.S. thesis defense. Dedeepya successfully defended her M.S. thesis.  Congratulations!


08/2018: Student award. Jacob Faulkner joined our group as an MS student and receives the Lozar Fellowship from the School of Mechanical Engineering. Congratulations, Jacob!


08/2018: Student award. Luis Delgado joined our group as a Ph.D. student and receives the Carver Fellowship from Purdue. Congratulations, Luis!


08/2018: Welcome New Students. Luis Delgado, Jacob Faulkner, and Peiyan Yao have joined our group. Welcome!


[more news ...]

Mission Statement:


Sustainable energy and thermal management are among the greatest challenges facing the society, and heat transfer researchers can contribute. Solutions to these challenges rely on extraordinarily fundamental and innovative approaches. In our lab, we are developing renewable energy technologies and thermal management solutions for electronics using the emerging nanotechnology.


The behavior of all energy systems can be related to atomic-scale description. With an atomic-level knowledge of the thermal energy carriers (photon, electron, phonon, and fluid particle), one is able to design nano- and micro-structures with the desired size effects, or to synthesize new materials with the desired functionalities. Our lab is building and expanding the understanding of the fundamentals of atomic-level carrier transport and interactions, and is applying this knowledge to important applications for energy efficiency and electronics thermal management technologies.


Current projects fall in two main themes: nanoscale heat conduction, and nano-photonics (including nanoscale thermal radiation). Projects in the nanoscale heat conduction (or nano-phononics) category include: (1) high-performance nanostructured thermoelectric materials for power generation and thermoelectric refrigeration; (2) thermal transport and thermal rectification in carbon nanotube and graphene for electronic thermal management applications; (3) thermal interface resistance across CNT (or graphene)-metal interfaces for electronic thermal management applications. Projects in the nano-photonics category include: (4) Suppression of electron-phonon coupling in quantum dot solar cell materials for enhanced efficiency; (5) Enhanced optical absorption in silicon nanowire arrays for potentially enhanced solar cell efficiency; (6) Multiscale control of thermal radiation in ordered array of carbon nanotubes; (7) enhanced laser cooling of semiconductors and ion-doped solids.


These projects involve theoretical, computational, and experimental components. Currently our lab devotes 2/3 efforts to theoretical and simulation studies, and 1/3 effort to experimental work. Theoretical tools include heat transfer, materials science, quantum mechanics, solid state physics, optics, and electromagnetic theory. Computational tools involve multiscale simulation techniques of nanoscale energy transport, including molecular dynamics simulations, first principles calculations, Monte-Carlo simulations, and Boltzmann transport theory. Experiments include fabrication of nanomaterials and devices, and characterizations of these materials and devices using advanced imaging and spectroscopy techniques. Detailed information of our research can be found here.


We have labs in both the ME building and the Birck Nanotechnology Center. We are also associated with the Energy Center at Purdue.

Most Recent Publications:


[105] Z.X. Lu and X.L. Ruan, "Non-equilibrium thermal transport: a review of applications and simulation approaches," ES Energy & Environment, accepted (2019).


[104] P.R. Chowdhury, T.L. Feng, and X.L. Ruan, "Development of interatomic potentials for the complex binary compound Sb2Te3 and the prediction of thermal conductivity," Phys. Rev. B, accepted (2019).


[103] Z.X. Lu, J.J. Shi, and X.L. Ruan, "Role of phonon coupling and non-equilibrium near the interface to interfacial thermal resistance: The multi-temperature model and thermal circuit," J. Appl. Phys. 125, 085107 (2019). [PDF]


[102] X.L. Li, W.J. Park, Y. Wang, Y.P. Chen, and X.L. Ruan, "Reducing interfacial thermal resistance between metal and dielectric materials by a metal interlayer," J. Appl. Phys. 125, 045302 (2019). [PDF]


[101] T.L. Feng, Y. Zhong, J.J. Shi, and X.L. Ruan, "Unexpected high inelastic phonon transport across solid-solid interface: Modal nonequilibrium
molecular dynamics simulations and Landauer analysis," Phys. Rev. B 99, 045301 (2019). [PDF]


[100] J. Peoples, X.Y. Li, Y Lv, J Qiu, Z.F. Huang, and X.L. Ruan, "A strategy of hierarchical particle sizes in nanoparticle composite for enhancing solar reflection," Int. J. Heat Mass Trans. 131, 487-494 (2019). [PDF]


[complete list of publications]

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