Page 208 - Mechanical Engineers' Handbook (Volume 4)

4 Boiling and Condensation Heat Transfer 197

Figure 27 Pressure correction for CO 2 total emissivity for values of P other than 1 atm. (Adapted from
Ref. 21. Used with the permission of McGraw-Hill Book Company.)

4 BOILING AND CONDENSATION HEAT TRANSFER
Boiling and condensation are both forms of convection in which the fluid medium is un-
dergoing a change of phase. When a liquid comes into contact with a solid surface maintained
at a temperature above the saturation temperature of the liquid, the liquid may vaporize,
resulting in boiling. This process is always accompanied by a change of phase, from the
liquid to the vapor state, and results in large rates of heat transfer from the solid surface,
due to the latent heat of vaporization of the liquid. The process of condensation is usually
accomplished by allowing the vapor to come into contact with a surface at a temperature
below the saturation temperature of the vapor, in which case the liquid undergoes a change
in state from the vapor state to the liquid state, giving up the latent heat of vaporization.

and P other than 0
Figure 28 Pressure correction for water vapor total emissivity for values of P HO
2
and 1 atm. (Adapted from Ref. 21. Used with the permission of McGraw-Hill Book Company.)