![]() Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 8-1. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983). Latent heat of vaporization – water at 0.1 MPa. The heat that is necessary to melt (or freeze) a unit mass at the substance at constant pressure is the heat of fusion and is equal to h sl = h l − h s, where h s is the enthalpy of saturated solid and h l is the enthalpy of saturated liquid. The heat of vaporization is the heat required to completely vaporize a unit of saturated liquid (or condense a unit mass of saturated vapor) and it equal to h lg = h g − h l. 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 is the amount of heat added to or removed from a substance to produce a change in phase. In case of liquid to gas phase change, this amount of energy is known as the enthalpy of vaporization, (symbol ∆H vap unit: J) also known as the (latent) heat of vaporization or heat of evaporation. In general, when a material changes phase from solid to liquid, or from liquid to gas a certain amount of energy is involved in this change of phase. Latent Heat of Vaporization The heat of vaporization diminishes with increasing pressure, while the boiling point increases.
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