Noncondensation

Noncondensation refers to a property of certain systems or processes where condensation, the change of a substance from a gaseous to a liquid state, does not occur under specified conditions. This can be relevant in various scientific and engineering contexts, from thermodynamics to materials science.

In thermodynamics, noncondensing gases are those that will not liquefy at a given temperature and pressure, even if cooled or compressed sufficiently. This behavior is often observed at temperatures significantly above the substance's critical temperature. For example, at room temperature and atmospheric pressure, nitrogen and oxygen are considered noncondensing gases because their boiling points are far below this.

In the context of engines and power systems, "noncondensing" often describes a steam turbine that exhausts steam directly to the atmosphere or to a process rather than to a condenser. This type of turbine is typically used in applications where the waste heat from the exhaust steam can be utilized for heating or industrial processes, a configuration known as cogeneration or combined heat and power. Noncondensing turbines are generally less efficient in terms of electrical power generation compared to condensing turbines because they do not recover energy from the phase change of steam.

The concept of noncondensation is also important in atmospheric science, particularly when discussing cloud formation. For water vapor to condense into liquid water droplets or ice crystals, the air must be supersaturated, and condensation nuclei must be present. If these conditions are not met, the water vapor remains as a gas, and condensation does not occur, even at temperatures that would otherwise favor it.