Question

One way to make a fireplace more energy efficient is to have an external air supply for the combustion of its fuel. Another is to have room air circulate around the outside of the fire box and back into the room. Detail the methods of heat transfer involved in each.

Short answer

During both the processes, convection takes place and thus efficiency is increased by energy transfer in the form of heat.

Step-by-step solution

Explain how the efficiency of the fireplace increases with the air supply.

For complete combustion of fuel, an external air supply is used. Since air is a fluid, heat transfer takes place through convection, and more oxygen will be added for the combustion of fuel. The heat energy is easily transferred as more air is used, so efficiency increases.

Explain how circulating the air in the room increases the efficiency of the fireplace.

The air circulating in the room will spread heat to all parts of the room. When the air becomes heated, it moves towards colder air and transfers the heat by the process of convection. Thus, colder air is replaced by hotter air. Ultimately, the entire room becomes hot.

So, the supply of external air and the circulation of air in the room increase the efficiency of the fireplace through convection.