Two-phase pressure drop and flow visualization of FC-72 in a silicon microchannel heat sink

Ayman Megahed, Ibrahim Hassan

Research output: Contribution to journalArticle

36 Citations (Scopus)


The rapid development of two-phase microfluidic devices has triggered the demand for a detailed understanding of the flow characteristics inside microchannel heat sinks to advance the cooling process of micro-electronics. The present study focuses on the experimental investigation of pressure drop characteristics and flow visualization of a two-phase flow in a silicon microchannel heat sink. The microchannel heat sink consists of a rectangular silicon chip in which 45 rectangular microchannels were chemically etched with a depth of 276 μm, width of 225 μm, and a length of 16 mm. Experiments are carried out for mass fluxes ranging from 341 to 531 kg/m2 s and heat fluxes from 60.4 to 130.6 kW/m2 using FC-72 as the working fluid. Bubble growth and flow regimes are observed using high speed visualization. Three major flow regimes are identified: bubbly, slug, and annular. The frictional two-phase pressure drop increases with exit quality for a constant mass flux. An assessment of various pressure drop correlations reported in the literature is conducted for validation. A new general correlation is developed to predict the two-phase pressure drop in microchannel heat sinks for five different refrigerants. The experimental pressure drops for laminar-liquid laminar-vapor and laminar-liquid turbulent-vapor flow conditions are predicted by the new correlation with mean absolute errors of 10.4% and 14.5%, respectively.

Original languageEnglish
Pages (from-to)1171-1182
Number of pages12
JournalInternational Journal of Heat and Fluid Flow
Issue number6
Publication statusPublished - 1 Dec 2009



  • Flow visualization
  • Heat sink
  • Pressure drop
  • Two-phase flow

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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