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.
| 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 |
Read more about this topic: Nucleate Boiling
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