Page 32 - BASIC CONCEPTUAL OF THERMOFLUID

CHAPTER 3

PROPERTIES OF PURE
SUBSTANCE

A substance that has a fixed chemical
composition throughout is called a pure
substance. Water , nitrogen, helium and
carbon dioxide, for example are all pure
substance.s

3.1 Phases of pure substances

There are many practical situations where two phases of pure substances coexist in equilibrium
E.g water exists as a mixture of liquid and vapor in the boiler and etc
§ Solid: strong intermolecular bond
§ Liquid: intermediate intermolecular bonds
§ Gas: weak intermolecular bond

3.2 Phase-change processes of pure substances

Compresses liquid (subcooled liquid): a substance that it is not about to vaporize
Saturated liquid: A liquid that is about to vaporize
Saturated liquid-vapor mixture: The state at which the liquid and vapor phases coexist in
equilibrium
Saturated vapor: A vapor that is about to condense
Superheated vapor: A vapor that is not about to condense (i.e.,not a saturated vapor)

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