Properties of Pure Substance

Pure substance

is a working substance that has homogenous and invariable chemical composition even though there is a change of phase.

Triple Point

where all three phases of a substance—solid, liquid, and gas—coexist in equilibrium.

The triple point

is determined by the intersection of the solid-liquid, liquid-gas, and solid-gas boundaries on the diagram.

Critical Point

point represents the highest pressure and highest

temperature at which liquid and vapor can coexist in equilibrium.

Critical Point

The state of water at critical conditions whether it is saturated

liquid or saturated vapor is known.

zero or undefined.

the latent heat of vaporization of water at Critical Point is either

Saturation Temperature

at which liquids start to boil (vaporize) or the temperature at which vapor begin to condense

Saturation Pressure

pressure at which a liquid starts to boil (vaporize) or a vapor begins to condense at a given temperature

Saturation Pressure

is the equilibrium pressure between the liquid and vapor phases of a pure substance at that temperature.

Saturated Liquid

liquid at the saturations (saturation temperature or saturation pressure), which has

temperature equal to the boiling point corresponding to the existing pressure. It is a pure liquid, i.e., it has no vapor content.

saturated vapor

is a vapor at the saturation conditions (saturation temperature and saturation pressure). it is 100% vapor has no liquid content or moisture

Compressed Liquid

is one, which has a pressure higher than the saturation pressure corresponding to the existing temperature.

Subcooled Liquid

is one, which has a temperature lower than the saturation

temperature corresponding to the existing pressure.

superheated vapor

having a temperatire higher than the saturation temperature corresponding to the existing pressure

degree of superheat

the difference between the actual temperature of superheated vapor and the saturation temperature for the existing pressure.

degrees of sub cooled

is the difference between the saturation temperature for the given pressure and the actual sub cooled liquid temp

wet vapor/ wet steam

is a combination of saturated vapor and saturated liquid.

y=100%

x=0%

percentage of x and y for saturated liquid

y=0%

x=100%

percentage of x and y for saturated vapor

0<x<100

0<y<100

percentage of x and y for wet vapor

sensible heat

heat that causes change in temp without a change in phase

latent heat

heat that causes changes in phase without change in temp

Latent Heat of Vaporization, hfg

of a pure substance is the amount of heat energy required change a substance from liquid → vapor (boiling/evaporation) or vapor → liquid (condensation) at constant temperature.

Latent Heat of Fusion

The amount of heat required to change a substance from solid →

liquid (melting) or liquid → solid (freezing) at constant

temperature.

degree of superheat formula

degree of subcooled formula

Quality, x formula

percent moisture y formula

latent heat of fusion formula

mf=m(1-x) or mf=m-m_vap

formula of mass liquid, mf

mg=mx

formula of mass of vapor, mg

Vg=(mg)(vg)

formula of volume of vapor, Vg

Vf=(mf)(vf)

formula of volume of liquid, Vf