![]() The change from the liquid to the vapor state due to boiling is sustained by heat transfer from the solid surface conversely, condensation of a vapor to the liquid state results in heat transfer to the solid surface. Above the critical point, the liquid and vapor phases are indistinguishable, and the substance is called a supercritical fluid. It vanishes completely at a certain point called the critical point. The heat of vaporization diminishes with increasing pressure, while the boiling point increases. ![]() Latent heat of vaporization – water at 16 MPa (pressure inside a pressurizer) Latent heat of vaporization – water at 3 MPa (pressure inside a steam generator) Latent heat of vaporization – water at 0.1 MPa (atmospheric pressure) The enthalpy of vaporization is a function of the pressure at which that transformation takes place. ![]() When latent heat is added, no temperature change occurs. This energy breaks down the intermolecular attractive forces, and also must provide the energy necessary to expand the gas (the pΔV work). Latent heat, known also as the enthalpy of vaporization, is the amount of heat added to or removed from a substance to produce a change in phase. In particular, we consider processes that can occur at a solid–liquid or solid–vapor interface, namely, boiling (liquid-to-vapor phase change) and condensation (vapor-to-liquid phase change).įor these cases latent heat effects associated with the phase change are significant. In this chapter we focus on convective heat transfer associated with the change in phase of a fluid. We have assumed a single-phase convective heat transfer without any phase change. In preceding chapters, we have discussed convective heat transfer with very important assumption. Boiling and Condensation Phase diagram of water.
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