Math 2.0

Classical thermodynamics, heat transfer Definition

Boiling heat transfer

Builds on Convective heat transferLatent heatHeat transfer coefficientHeat fluxTemperature

Definition

Consider a solid surface at temperature TwT_w in contact with a liquid. Let TsatT_{\mathrm{sat}} be the saturation temperature of the liquid at the local pressure. Boiling heat transfer is convective heat transfer from the surface to the liquid with Tw>TsatT_w > T_{\mathrm{sat}}. In it, vapour is generated at the surface, as bubbles or as a vapour film. The difference ΔTe=Tw−Tsat\Delta T_e = T_w - T_{\mathrm{sat}} is the excess temperature (or wall superheat), and the heat flux is written q′′=h ΔTeq'' = h \, \Delta T_e with a heat transfer coefficient hh.

Remarks

Example: water at atmospheric pressure, Tsat=100T_{\mathrm{sat}} = 100 °C, on a plate at 110110 °C. Here ΔTe=10\Delta T_e = 10 K, vapour bubbles form at the plate, and the regime is nucleate boiling.

Non-example: evaporation of a pond in the sun. Vapour leaves the free surface, but no surface in contact with the water is above TsatT_{\mathrm{sat}} and no vapour forms at a wall, so this is not boiling.

As ΔTe\Delta T_e grows, the regimes are: natural convection without bubbles, nucleate boiling, transition boiling, and film boiling. The heat flux has a maximum, the critical heat flux, at the end of nucleate boiling. For water at atmospheric pressure it is of order 10610^6 W/m2^2. It is reached at ΔTe\Delta T_e around 3030 K. The vapour carries the latent heat of vaporisation, which is why hh is large. If the bulk liquid is below TsatT_{\mathrm{sat}} the boiling is called subcooled, and if it is at TsatT_{\mathrm{sat}} it is called saturated.

Reading path

To understand this page from the ground up, read these 6 pages in order. The foundations come first.

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Convective heat transfer, concept, no evidence levelConvective heat trans…conceptHeat flux, concept, no evidence levelHeat fluxconceptHeat transfer coefficient, concept, no evidence levelHeat transfer coeffic…conceptLatent heat, concept, no evidence levelLatent heatconceptTemperature, concept, no evidence levelTemperatureconceptBoiling heat transfer, definition, no evidence levelBoiling heat transferdefinition
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  1. Convective heat transfer concept
  2. Heat flux concept
  3. Heat transfer coefficient concept
  4. Latent heat concept
  5. Temperature concept
  6. Boiling heat transfer definition

Further reading

  1. Web https://en.wikipedia.org/wiki/Nucleate_boiling
About this page
TagH17SE6HQFV
URIm2://H17SE6HQFV
Kinddefinition
WritingW0 stub
MSC80A19, 80A22, 76T10
DefinesBoiling heat transfer
UsesConvective heat transfer, Latent heat, Heat transfer coefficient, Heat flux, Temperature
Changed3 November 2026

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