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When the phase change occurs, there is a "thermal arrest"; that is, the temperature stays constant. This is because the matter has more internal energy as a liquid or gas than in the state that it is cooling to. The amount of energy required for a phase change is known as latent heat. The "cooling rate" is the slope of the cooling curve at any ...
In problems of heat transfer with phase change, for instance, conservation of energy dictates that the discontinuity of heat flux at the boundary must be accounted for by the rate of latent heat release (which is proportional to the local velocity of the interface).
In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter : solid , liquid , and gas , and in rare cases, plasma .
Latent heat is associated with the change of phase of atmospheric or ocean water, vaporization, condensation, freezing or melting, whereas sensible heat is energy transferred that is evident in change of the temperature of the atmosphere or ocean, or ice, without those phase changes, though it is associated with changes of pressure and volume.
A phase-change material (PCM) is a substance which releases/absorbs sufficient energy at phase transition to provide useful heat or cooling. Generally the transition will be from one of the first two fundamental states of matter - solid and liquid - to the other.
Heat therapy, also called thermotherapy, is the use of heat in therapy, such as for pain relief and health. It can take the form of a hot cloth, hot water bottle , ultrasound , heating pad , hydrocollator packs, whirlpool baths , cordless FIR heat therapy wraps, and others.
The latent internal energy of a system is the internal energy a system requires to undergo a phase transition. Its value is specific to the substance or mix of substances in question. The value can also vary with temperature and pressure. Generally speaking the value is different for the type of phase change being accomplished.
Mathematically, = =, where / is the slope of the tangent to the coexistence curve at any point, is the molar change in enthalpy (latent heat, the amount of energy absorbed in the transformation), is the temperature, is the molar volume change of the phase transition, and is the molar entropy change of the phase transition. Alternatively, the ...