PSYCHOMETRIC PROPERTIES

Psychometric is the field of engineering concerned with the physical and thermodynamic properties of gas-vapor mixtures

1. Dry air

Dry air is air that has no water vapor in it. In other words, it has 0% humidity.

2. Moist air

Moist air refers to the air with water vapor, and dry air is the air without water vapor.

3. Water vapour

Water vapor, water vapour or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice.It is less dense than most of the other constituents of air

4. Saturated air

Saturated air is air that holds water vapor at its highest level. Air is composed of moisture or water vapor, regardless of the amount of pressure and temperature levels. Adding more moisture to the air at a specific temperature and in an enclosed area causes the air to absorb the moisture.

5. Dry bulb temperature

The dry-bulb temperature is the temperature indicated by a thermometer exposed to the air in a place sheltered from direct solar radiation. The thermodynamic wet-bulb temperature is a thermodynamic property of a mixture of air and water vapor. The value indicated by a wet-bulb thermometer often provides an adequate approximation of the thermodynamic wet-bulb temperature.

A psychrometer is a device that includes both a dry-bulb and a wet-bulb thermometer. A sling psychrometer requires manual operation to create the airflow over the bulbs, but a powered psychrometer includes a fan for this function. Knowing both the dry-bulb temperature (DBT) and wet-bulb temperature (WBT), one can determine the relative humidity (RH) from the psychrometric chart appropriate to the air pressure.

6. Wet bulb depression

The wet bulb depression is the difference between the dry-bulb temperature (Air temperature) and the wet-bulb temperature.

7. Dew point temperature

The saturation temperature of the moisture present in the sample of air, it can also be defined as the temperature at which the vapour changes into liquid (condensation).

8. Dew point depression

The dew point depression (T-Td) is the difference between the temperature and dew point temperature at a certain height in the atmosphere.

9. Humidity

Humidity is the concentration of water vapour present in the air.

10. Specific and relative humidity

Specific humidity - Specific humidity is defined as the mass of water vapor as a proportion of the mass of the moist air sample (including both dry air and the water vapor); it is closely related to humidity ratio and always lower in value.

Relative humidity - The ratio of the vapor pressure of moisture in the sample to the saturation vapor pressure at the dry bulb temperature of the sample.

11. Sensible heating and cooling

Sensile heating - Sensible heat refers to heat you can feel, or sense. This is any heat which can be measured on a thermometer, whether it's heat from the sun shining on a sunny day, or the flame from a candle. When an object is heated, the object's increase in temperature is sensible heat.

Sensible cooling – The cooling in which temperature of air is reduced without changing in its moisture content.

12. Humidification

Humidification - is the process in which the moisture or water vapor or humidity is added to the air. Common equipment used in this process is a humidifier.

13. Dehumidification

The dehumidification process is the inverse of adding water to the room with an evaporative cooler, and instead releases heat. Therefore, an in-room dehumidifier will always warm the room and reduce the relative humidity indirectly, as well as reducing the humidity more directly, by condensing and removing water.

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