Q1: Draught produced by a tall chimney due to density difference between hot flue gas inside the Chimney and atmospheric air outside the chimney is more appropriately known as the __________ draught.

ANS:A - natural

The draught produced by a tall chimney due to the density difference between hot flue gas inside the chimney and atmospheric air outside the chimney is more appropriately known as natural draught. Explanation:

1. Natural Draught: Natural draught, also known as chimney draught or stack effect, is the draught or airflow created in a chimney or flue due to the difference in density between the hot gases inside the chimney and the cooler ambient air outside. This difference in density causes the hot gases to rise and create a natural upward flow through the chimney.
2. Mechanism: Natural draught occurs because hot gases are less dense than cold gases. As the hot flue gases rise in the chimney, they create a negative pressure or suction at the base of the chimney, drawing in fresh air to replace the rising gases. This natural airflow helps to remove combustion products and maintain efficient combustion in furnaces, boilers, and other combustion devices.
3. Characteristics: Natural draught operates without the need for mechanical devices such as fans or blowers. It relies solely on the buoyancy effect created by the temperature difference between the hot gases and the surrounding air. The intensity of natural draught depends on factors such as the height and diameter of the chimney, temperature difference, and atmospheric conditions.
4. Comparison with Other Types of Draught:
   • Induced Draught: Induced draught is created by mechanical devices such as fans or blowers, which actively draw gases out of the combustion chamber and expel them through the chimney. This type of draught is not reliant on the buoyancy effect and can be controlled more easily.
   • Forced Draught: Forced draught is similar to induced draught but refers specifically to the use of mechanical devices to force air into the combustion chamber, increasing the combustion air supply and enhancing combustion efficiency.