Biporous media consisting of microscale pin fins separated by microchannels are examined as candidate structures for the evaporator wick of a vapor chamber heat pipe. The structures are fabricated out of silicon using standard lithography and etching techniques. Pores which separate microscale pin fins are used to generate high capillary suction, while larger microchannels are used to reduce overall flow resistance. The heat transfer coefficient is found to depend on the area coverage of a liquid film with thickness on the order of a few microns near the meniscus of the triple phase contact line. We manipulate the area coverage and film thickness by varying the surface area-to-volume ratio through the use of microstructuring. Experiments are conducted for a heater area of 1 cm2 with the wick in a vertical orientation. Results are presented for structures with approximately same porosities, fixed microchannel widths w ≈ 30 μm and w ≈ 60 μm, and pin fin diameters ranging from d = 3–29 μm. The competing effects of increase in surface area due to microstructuring and the suppression of evaporation due to reduction in pore scale are explored. In some samples, a transition from evaporative heat transfer to nucleate boiling is observed. While it is difficult to identify when the transition occurs, one can identify regimes where evaporation dominates over nucleate boiling and vice versa. Heat transfer coefficients of 20.7 (±2.4) W/cm2-K are attained at heat fluxes of 119.6 (±4.2) W/cm2 until the wick dries out in the evaporation dominated regime. In the nucleate boiling dominated regime, heat fluxes of 277.0 (±9.7) W/cm2 can be dissipated by wicks with heaters of area 1 cm2, while heat fluxes up to 733.1 (±103.4) W/cm2 can be dissipated by wicks with smaller heaters intended to simulate local hot-spots.
Skip Nav Destination
e-mail: Arun.Majumdar@hq.doe.gov
Article navigation
Evaporation, Boiling, and Condensation
Enhanced Heat Transfer in Biporous Wicks in the Thin Liquid Film Evaporation and Boiling Regimes
Dušan Ćoso,
Dušan Ćoso
Department of Mechanical Engineering,
University of California
, Berkeley, CA 94720-1740
Search for other works by this author on:
Vinod Srinivasan,
Vinod Srinivasan
Department of Mechanical Engineering,
University of California
, Berkeley, CA 94720-1740
Search for other works by this author on:
Ming-Chang Lu,
Ming-Chang Lu
Department of Mechanical Engineering,
National Chiao Tung University
, Hsinchu, Taiwan 30010
Search for other works by this author on:
Je-Young Chang,
Je-Young Chang
Intel Corporation, 5000 W. Chandler Boulevard, CH5-157,
Chandler
, AZ 85226
Search for other works by this author on:
Arun Majumdar
Arun Majumdar
Advanced Research Projects Agency-Energy (ARPA-E),
e-mail: Arun.Majumdar@hq.doe.gov
US Department of Energy
, Washington, D.C. 20585
Search for other works by this author on:
Dušan Ćoso
Department of Mechanical Engineering,
University of California
, Berkeley, CA 94720-1740
Vinod Srinivasan
Department of Mechanical Engineering,
University of California
, Berkeley, CA 94720-1740
Ming-Chang Lu
Department of Mechanical Engineering,
National Chiao Tung University
, Hsinchu, Taiwan 30010
Je-Young Chang
Intel Corporation, 5000 W. Chandler Boulevard, CH5-157,
Chandler
, AZ 85226
Arun Majumdar
Advanced Research Projects Agency-Energy (ARPA-E),
US Department of Energy
, Washington, D.C. 20585
e-mail: Arun.Majumdar@hq.doe.gov
J. Heat Transfer. Oct 2012, 134(10): 101501 (11 pages)
Published Online: August 7, 2012
Article history
Received:
March 13, 2011
Revised:
December 29, 2011
Published:
August 6, 2012
Online:
August 7, 2012
Citation
Ćoso, D., Srinivasan, V., Lu, M., Chang, J., and Majumdar, A. (August 7, 2012). "Enhanced Heat Transfer in Biporous Wicks in the Thin Liquid Film Evaporation and Boiling Regimes." ASME. J. Heat Transfer. October 2012; 134(10): 101501. https://doi.org/10.1115/1.4006106
Download citation file:
Get Email Alerts
Cited By
On Prof. Roop Mahajan's 80th Birthday
J. Heat Mass Transfer
Thermal Hydraulic Performance and Characteristics of a Microchannel Heat Exchanger: Experimental and Numerical Investigations
J. Heat Mass Transfer (February 2025)
Related Articles
Effect of Liquid Properties on Phase-Change Heat Transfer in Porous Wick Structures
J. Heat Transfer (March,2016)
Experimental Study of Surfactant Effects on Pool Boiling Heat Transfer
J. Heat Transfer (February,1990)
Investigation of Decisive Mixture Effects in Nucleate Boiling of
Binary Mixtures Using a Theoretical Model
J. Heat Transfer (December,2003)
Numerical Simulation of Evaporating Two-Phase Flow in a High-Aspect-Ratio Microchannel with Bends
J. Heat Transfer (August,2017)
Related Chapters
Experiment Investigation of Flow Boiling Process Including Cavitation in Micro-Channel
Inaugural US-EU-China Thermophysics Conference-Renewable Energy 2009 (UECTC 2009 Proceedings)
Insulating Properties of W-Doped Ga2O3 Films Grown on Si Substrate for Low-K Applications
International Conference on Advanced Computer Theory and Engineering, 4th (ICACTE 2011)
Energy Balance for a Swimming Pool
Electromagnetic Waves and Heat Transfer: Sensitivites to Governing Variables in Everyday Life