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Proceedings of Symposium on Energy Engineering in the 21<sup>st</sup> Century (SEE2000) Volume I-IV

ISSN:
1-56700-132-7 (Print)

MICROSCALE HEAT TRANSFER AT FAST TIME STUDIED BY NOVEL LASER-BASED MEASUREMENT TECHIQUES

K. X. He
Department of Physics, Alabama A & M University, Normal AL 35762

J. C. Wang
Department of Physics, Alabama A & M University, Normal AL 35762

Alan Chow
National Aeronautics and Space Administration, George C. Marshall Space Flight Center, Marshall Space Flight Center, AL 35812

Jiada Mo
Department of Mechanical Engineering, Memphis State University, 322 Engineering Science, Memphis, TN 38152

Carl Holden
National Aeronautics and Space Administration, Langley Research center, Hampton, VA 23681

Abstract

In present paper we report on the first study of transient microscale heat transfer in liquid which contained the nature organic material of Chinese tea solution. Heat transport by phonons has been studied by single picosecond pulse degenerate four wave mixing (DFWM) technique. The sound velocity in Chinese tea solution was measured as 1133.6 m/s which is compared with the sound velocity in methanol. The molecules of Chinese tea can absorb a photon and then relax non-radiatively or radiatively back to the electronics ground state. Ultrafast laser induced fluorescence (ULIF) at 674. lnm was recorded and radiative transition for the Chinese tea molecules was very strong. Convection in Chinese tea solution has also been studied by self action with both horizontal- and vertical laser propagation through the Chinese tea cell. The dependence of the location of the red ULIF on the intensity of the laser beams clearly show that the real behavior of Chinese tea molecules in transient heat transport.