latent heat


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latent heat,

heat change associated with a change of state or phase (see states of matterstates of matter,
forms of matter differing in several properties because of differences in the motions and forces of the molecules (or atoms, ions, or elementary particles) of which they are composed.
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). Latent heat, also called heat of transformation, is the heatheat,
nonmechanical energy in transit, associated with differences in temperature between a system and its surroundings or between parts of the same system. Measures of Heat
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 given up or absorbed by a unit mass of a substance as it changes from a solid to a liquid, from a liquid to a gas, or the reverse of either of these changes. It is called latent because it is not associated with a change in temperature. Each substance has a characteristic heat of fusion, associated with the solid-liquid transition, and a characteristic heat of vaporization, associated with the liquid-gas transition. The latent heat of fusion for ice is 80 calories per gram (see caloriecalorie,
abbr. cal, unit of heat energy in the metric system. The measurement of heat is called calorimetry. The calorie, or gram calorie, is the quantity of heat required to raise the temperature of 1 gram of pure water 1°C;.
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). This amount of heat is absorbed by each gram of ice in melting or is given up by each gram of water in freezing. The latent heat of vaporization of steam is 540 calories per gram, absorbed during vaporizationvaporization,
change of a liquid or solid substance to a gas or vapor. There is fundamentally no difference between the terms gas and vapor, but gas is used commonly to describe a substance that appears in the gaseous state under standard conditions of pressure and
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 or given up during condensationcondensation,
in physics, change of a substance from the gaseous (vapor) to the liquid state (see states of matter). Condensation is the reverse of vaporization, or change from liquid to gas.
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. For a substance going directly from the solid to the gas state, or the reverse, the heat absorbed or given up is known as the latent heat of sublimationsublimation
, change of a solid substance directly to a vapor without first passing through the liquid state. The term is also used to describe the reverse process of the gas changing directly to the solid again upon cooling.
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.

latent heat

[′lāt·əŋt ′hēt]
(thermodynamics)
The amount of heat absorbed or evolved by 1 mole, or a unit mass, of a substance during a change of state (such as fusion, sublimation or vaporization) at constant temperature and pressure.

latent heat

The amount of heat which is absorbed or evolved in changing the state of a substance without changing its temperature, e.g., in freezing or vaporizing water.
References in periodicals archive ?
The third method started with determining a new function for the latent heat of vaporization, by comparing the saturation vapor pressures derived from the Clausius-Clapeyron equation (which assumes temperature-dependent variable values of [l.
The latent heat of vaporization is indirectly proportional to the moisture content of crambe fruits, and the increase in temperature at the same moisture content reduced the latent heat of vaporization.
Thermal energy can be accumulated as a change in interior energy of a material as sensible heat, latent heat or thermochemical or mixture of these.
The SWHX recovers the sensible and latent heat of low temperature flue gas, the GWHX recovers the sensible heat of medium temperature flue gas while the condenser recovers the sensible heat of high temperature flue gas with water vapor as the heat transfer medium.
With the linearization of the vapor pressure, the latent heat as a function of temperature and the equilibrium moisture content were calculated.
The Bowen ratio ([beta]), which is the sensible heat flux divided by the latent heat flux, is a parameter used to verify the water conditions of the environment, and the lower its value, the greater the water availability, and the inverse is true and an indication that in drought conditions, a larger portion of the energy available in the environment is used to heat the atmosphere (sensible heat flux).
Thermal performance evaluation of a latent heat storage unit for late evening cooking in a solar cooker having three reflectors.
L] is the Vaporization latent heat flux coefficient which has been measured with regard to wind speed and temperature difference (sea-air) in all the year months.
Lower heating value: the heat value of a combustion process excluding latent heat from vaporization of water.
An open-circuit cooling tower relies solely on latent heat removal during the evaporation of water for its heat dissipation.
Latent heat is the energy needed to change a material from one phase to another--to boil water or melt a salt; a material changes phase without changing temperature at constant pressure.
When such a material freezes, it releases large amounts of energy in the form of latent heat of fusion, or energy of crystallisation.