Lesson 4 Flashcards
It is the study of the properties of air, and use of the psychrometric
chart are essential for an understanding of the processes involved in
drying and storage of grains and other agricultural crops, and for analyzing individual requirements for a particular climatic condition.
Psychometrics
It is the field of engineering concerned with the physical and thermodynamic properties of gas-vapor mixtures.
Psychometrics
A state of matter that is liquid at its core, but it is in a gaseous state. It has a lower temperature than gas.
Vapor
A gaseous state
throughout.
Gas
What is the main difference between vapor and gas?
Temperature
Process 0-1
Sensible Heating
Process 0– 2
Sensible cooling
Process 0– 3
Humidifying
Process 0– 4
Dehumidifying
Process 0– 5
Heating and Humidifying
Process 0– 6
Cooling and Dehumidifying
Process 0– 7
Cooling and Humidifying
Process 0–8
Heating and Dehumidifying
A mechanical mixture of gases and
water vapor.
Air
Types of air
Dry air
Moist air
Saturated air
What is the relative molecular mass of all components
for dry air?
28.9645 g/mol
Mixture of various gases in the absence of water vapour.
Dry Air
The mixture of dry air and water vapour. The amount of water present in air depends on the pressure and temperature of the mixture.
Moist Air
The mixture of dry air and water vapour when air has diffused maximum amount of water vapour into it.
Saturated Air
When condensation and evaporation are
equal, this is called?
Saturation
Also called Specific Humidity. The ratio of the weight of water vapor to the weight of completely dried air. It is the weight of the water vapor contained in the moist air per unit weight of dry air. Other term used for this is absolute humidity. Expressed as pound per pound or kg/kg or no unit.
Humidity Ratio
A measure of its fractional saturation with moisture. It is defined as the ratio of the partial pressure of water vapor to the saturated vapor pressure.
Relative Humidity, %
Temperature indicated by a thermometer which is unaffected by moisture or radiation. It is the temperature of the air as measured using an ordinary thermometer, such as a household thermometer. The bulb is the sensitive portion of the instrument. As the temperature of the bulb increases, the liquid in the bulb expands and rises in the stem (thermal expansion).
Dry Bulb Temperature
Temperature of the air measured by a mercury thermometer whose glass bulb is covered by a wick or wet cloth or gauze. The clean cotton wick absorbs water. Also, and the airflow passing over the wick at least 5 m/s. Evaporation of this water reduces the temperature of the wick, and the resultant temperature is indicated by the mercury in the thermometer stem.
Wet Bulb Temperature
