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Heat Pipe Science and Technology, An International Journal

Published 4 issues per year

ISSN Print: 2151-7975

ISSN Online: 2151-7991

EFFECT OF COMPOUND ENHANCEMENT TECHNIQUE ON POOL BOILING HEAT TRANSFER COEFFICIENT

Volume 7, Issue 3-4, 2016, pp. 251-264
DOI: 10.1615/HeatPipeScieTech.2017019384
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ABSTRACT

Efficient and innovative cooling techniques are required for cooling modern compact chips. Immersion cooling by pool boiling heat transfer is one of such methods, which is a highly efficient technique when compared with conventional cooling techniques. Enhancement of the boiling heat transfer coefficient can be achieved using active and passive techniques. A compound augmentation method in which active and passive techniques are coupled to improve the boiling heat transfer coefficient is investigated in the present work. Circular copper boiling surface with rectangular grooves is the passive enhancement technique and boiling surface vibration is the active enhancement technique. Forced vertical vibrations were induced on this copper grooved surface with a mechanical vibrator. The frequency was varied in the range 0–100 Hz and the amplitude of vibration was varied in the range 0–2.5 mm for lower frequencies (2, 5, and 10 Hz). Increase in boiling heat transfer rate was 78% with compound technique. The maximum increase of 40% in the boiling heat transfer coefficient values was obtained when the grooved surface was vibrated at 25 Hz frequency and 1 mm amplitude. An increase of 36% in the heat transfer rate was observed for 2.5-mm amplitude and 2-Hz frequency of vibration of the copper grooved surface. Visualization of boiling phenomena was carried and the bubble parameters such as bubble departure diameter, bubble frequency, and bubble growth were determined. An average of 30 bubble life cycles which are not coalesced were considered to obtain the average bubble diameter and bubble frequency from the same nucleation site. The bubble departure diameter decreased by almost 36% and the bubble frequency increased by 221% in enhanced boiling.

CITED BY
  1. Mata Arenales Mario R., C.S. Sujith Kumar, Kuo Long-Sheng, Chen Ping-Hei, Surface roughness variation effects on copper tubes in pool boiling of water, International Journal of Heat and Mass Transfer, 151, 2020. Crossref

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