Critical Temperature (Tc)
The maximum temperature at which a gas can be converted into a liquid by an increase in
pressure.
Critical Pressure (Pc)
The minimum pressure would suffice to liquefy a substance at its critical temperature. Above the critical pressure, increasing the temperature will not cause fluid to vaporize to give a two-phase system.
Critical Point
The characteristic temperature (Tc) and pressure (pc) above which a gas cannot be liquefied.
Supercritical Fluid
The defined state of a compound, mixture, or element above its critical pressure (Pc) and critical temperature (Tc).
Reduced Temperature (Tr)
The ratio of the temperature (T) in the system to the critical temperature (Tc) Tr = T/Tc
Reduced Pressure (Pr)
The ratio of the pressure in the system (P) to the critical pressure (Pc). Pr = P/Pc
Saturated Steam Pressure Pv
Saturated vapor pressure refers to the gas pressure (partial pressure) of a substance in a confined space at a given temperature when the liquid and vapor phases of the substance coexist. At this time, the evaporation and condensation process reaches dynamic equilibrium. Generally, the higher the temperature of the water, the higher the vapor pressure. When the pressure (partial pressure) of the gas is equal to the saturated vapor pressure, the corresponding temperature is called the dew point, and the relative humidity of the air at this time is 100%. At this time, if the temperature is lowered or the content of water vapor in the air is increased, water condensation will occur. The saturated vapor pressure of water can be determined according to the equation.
Commonly used Medium Critical Pressure (Pc)
Medium | PC(100KPa Absolute Pressure) |
Acetic acid | 59 |
Acetone | 48.4 |
Acetylene | 63.7 |
Air | 38.2 |
Ammonia | 114.5 |
Nitrogen | 34.5 |
Fluorine | 25.7 |
Helium | 2.33 |
Hydrogen | 13.1 |
Argon | 49.4 |
Benzene | 49 |
Carbon dioxide | 75 |
Carbon monoxide | 36 |
Medium | PC (100KPa Absolute Pressure) |
Methane | 47.2 |
Methanol | 81 |
Oxygen | 51.2 |
Chlorine oxide | 73.8 |
Octane | 25.4 |
Chlorine | 73 |
Ethane | 50.2 |
Ethanol | 65 |
Hydrogen chloride | 84 |
Propane | 43.2 |
Sulfur dioxide | 80 |
Water | 224 |
Pentane | 34 |