Nucleate Boiling - Boiling Heat Transfer Correlations

Boiling Heat Transfer Correlations

The nucleate boiling regime is important to engineers because of the high heat fluxes possible with moderate temperature differences. The date can be correlated by equation of the form,

The Nusselt number is defined as,

where q/A is the total heat flux, is the maximum bubble diameter as it leaves the surface, is the excess temperature, is the thermal conductivity of the liquid and is the Prandtl number of the liquid. The bubble Reynolds number, is defined as,

Where is the average mass velocity of the vapor leaving the surface and is the liquid viscosity.

Rohsenow has developed the first and most widely used correlation for nucleate boiling,

Where is the heat capacity of the liquid. is the surface fluid combination and vary for various combinations of fluid and surface. For example, water and nickel have a of 0.006.

Values of for various surface fluid combinations
Surface fluid combinations
Water/copper 0.013
Water/nickel 0.006
Water/platinum 0.013
Water/brass 0.006
Water/Stainless steel, mechanically polished 0.0132
Water/Stainless steel, Chemically etched 0.0133
Water/Stainless steel, Ground and polished 0.0080
/copper 0.013
Benzene/Chromium 0.0101
n-Pentane/Chromium 0.015
Ethyl alcohol/Chromium 0.0027
Isopropyl alcohol/copper 0.0025
n-Butyl alcohol/copper 0.003

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