Jeremy Spitzenberger1, James Hoelle1, Ahmed Abdulheiba1, Ramy H. Mohammed1, Laith Ismael1,2, Damena Agonafer3, Pengtao Wang4, Stephen Kowalski4, Kashif Nawaz4, and Hongbin Ma1
1Department of Mechanical & Aerospace Engineering, University of Missouri, Columbia, MO 65211
2Department of Mechanical Engineering, University of Technology, Baghdad, Iraq
3Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
4Building Technologies Research and Integration Center (BTRIC), Oak Ridge National Laboratory, Oak Ridge, TN 37831
For more information about this article and related research, please contact Prof. Damena Agonafer.
Abstract:
Wicking structures have been widely used within passive heat transfer devices with high heat fluxes, such as heat pipes, to enhance their thermal performance. While wicking structures promote capillary pumping of the working fluid and thin film evaporation, they can result in capillary evaporation and further enhance the evaporation heat transfer. In this study, a 0.5 mm thick layer of 105 µm sintered copper particles was added to the inner wall of a copper tube, aiming to form an “annular flow” and enhance the heat transfer characteristics by taking advantage of thin film and capillary evaporation. Acetone was chosen as the working fluid, and the performance of an evaporation tube was tested for power inputs of 10, 30, 50, and 70 W. For each power input, trials were run at inclination angles varying from −90 deg to 90 deg to investigate the capillary effects. The temperature measurements showed that the temperature distribution along the evaporation tube is always downward sloping, meaning the temperature at the fluid inlet is larger than the outlet. Results show that an “annular flow” formed by a thin layer of sintered particles can promote thin film and capillary evaporation and, therefore, boost the evaporation heat transfer coefficient.
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