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Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications. II. Heat transfer characteristics.

Author(s) : LEE J., MUDAWAR I.

Type of article: Article

Summary

This article is the second of a two-part study concerning two-phase flow and heat transfer characteristics of R134a in a micro-channel heat sink incorporated as an evaporator in a refrigeration cycle. Boiling heat transfer coefficients were measured over a broad range of mass velocities. While prior studies point to either nucleate boiling or annular film evaporation (convective flow boiling) as dominant heat transfer mechanisms in small channels, the present study shows heat transfer is associated with different mechanisms for low, medium and high qualities. Nucleate boiling occurs only at low qualities corresponding to very low heat fluxes, and high fluxes produce medium quality or high quality flows dominated by annular film evaporation. Because of the large differences in heat transfer mechanism between the three quality regions, better predictions are possible by dividing the quality range into smaller ranges corresponding to these flow transitions. A new heat transfer coefficient correlation is recommended which shows excellent predictions for both R134a and water (see also this Bulletin, reference 2005-1730).

Details

  • Original title: Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications. II. Heat transfer characteristics.
  • Record ID : 2005-1731
  • Languages: English
  • Source: International Journal of Heat and Mass Transfer - vol. 48 - n. 5
  • Publication date: 2005/02

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