Define factors affect the rate and total drying time?

Four main factors affect the rate and total drying time, which include:

a) The properties of the products (the moisture content, surface area to volume ratio, surface temperature and rate of moisture), loss especially particle size and geometry; 

b) The geometrical arrangement of the products in relation to heat tansfer medium (drying air); 

c) The physical properties of drying medium/ environment; 

d) The characteristics of the drying equipment/drier (the dry bulb temperature, relative humidity).