Condensation occurs when the temperature of a vapor is reduced below its saturation
temperature. In industrial equipment, the process commonly results from
contact between the vapor and a cool surface (Figures 10.9a, b). The latent energy
of the vapor is released, heat is transferred to the surface, and the condensate is
formed. Other common modes are homogeneous condensation (Figure 10.9c),
where vapor condenses out as droplets suspended in a gas phase to form a fog,
and direct contact condensation (Figure 10.9d), which occurs when vapor is
brought into contact with a cold liquid. In this chapter we will consider only surface
condensation.