Vapor and Gas Mixtures

| Home | | Pharmaceutical Technology |

Chapter: Pharmaceutical Engineering: Air Conditioning and Humidification

The humidity of a vapor-gas mixture is defined as the mass of vapor associated with unit mass of the gas.


VAPOR AND GAS MIXTURES

The humidity of a vapor-gas mixture is defined as the mass of vapor associated with unit mass of the gas. This principle is generally applicable to any vapor present in any noncondensable gas. In this section, however, only water vapor in air is considered. The percent humidity is the ratio of ambient humidity to the humidity of the saturated gas at the same temperature, expressed as a per-centage. These terms should be carefully distinguished from the relative humidity with which they are distantly related. The relative humidity is the ratio of the partial pressure of the vapor in the gas to the partial pressure when the gas is saturated. This is also usually expressed as a percentage. The relative humidity of a given vapor-gas mixture changes with temperature, but the humidity does not.

The study of the properties of the air–water vapor mixture is called psy-chrometry, and data is presented in the form of psychrometric charts. These take various forms and present various data (Perry and Chilton, 1999). In Figure 6.1, humidity is plotted as the ordinate and temperature as the abscissa. Percent relative humidity is then plotted as a series of curves running across the chart. The use of this simplified chart is demonstrated later in this chapter and in the succeeding chapter.


FIGURE 6.1 A psychrometric chart that can be used to determine the humidity.

Contact Us, Privacy Policy, Terms and Compliant, DMCA Policy and Compliant

TH 2019 - 2023 pharmacy180.com; Developed by Therithal info.