Humidity
Percent relative humidity: The term percent
relative humidity is defined as the ratio of the partial pressure of water
vapor in the air to the vapor pressure of free water at the same temperature.
(The saturation humidity curve is thus the curve for 100% relative humidity.)
Curves of temperature versus absolute humidity at a constant relative humidity
are plotted on the same axes at specific intervals of relative humidity.
Theory of drying: A material may contain both bound and unbound
moisture and these two moistures are removed by drying process. So, drying
process is divided into two processes—
- Heat transfer &
- Mass transfer.
Heat transfer: Heat must be transferred to the material to be dried
in order to supply the latent heat required for vaporization of the moisture. When
heat is applied on the bottom of the particles, it is transferred from the
exterior portions to the inferior portions and gradually reaches to the core of
the particles. This is the usual theme of drying.
Heat may be transferred in
three ways:
- Conduction: In this process, heat is transferred without the movement of heated surface with solids.
- Convection: In this process, heat is transferred by the movement of heated substance that means for hot air.
Humidity
Reviewed by M H Islam
on
8:19 AM
Rating:
Reviewed by M H Islam
on
8:19 AM
Rating:
