The general assumption is that heat consumed in drying operation is very low. But it is not so, it is a wrong perception. The amount of heat consumed in drying operation is very high and it is in considerable amount. Since we are not seeing visible large fires, it is usually under estimated. A ceramic article weighing two and half lb and containing 30% of water requires 316 British thermal units to dry it at 20oC. For firing of 24 ounce of dry clay to 1200oC, 378 British Thermal units are needed theoretically. The heat required for firing of 1 lb of raw earthen ware body to 1200oC is estimated to be about 245 British thermal units. The above data shows that the heat required for drying amounts to 83% of heat required for firing.
To be contd…………..
