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.

a) External air supply: conduction and convection; Room air circulation: radiation and conduction.

b) External air supply: radiation and convection; Room air circulation: conduction and convection.

c) External air supply: conduction and radiation; Room air circulation: conduction and radiation.

d) External air supply: radiation and convection; Room air circulation: radiation and conduction.

Answer 1

To make a fireplace more energy-efficient, external air supply utilizes convection and radiation, while room air circulation around the firebox uses conduction and convection for heat transfer.

Step-by-step explanation:

When it comes to improving the energy efficiency of a fireplace, understanding the methods of heat transfer involved in different modifications is key. With an external air supply for the combustion of fuel, the heat transfer primarily involves convection, where the outside air is drawn into the fireplace, heated by the fire, and then rises due to its decreased density. Radiation also plays a role, as the fire emits electromagnetic waves that transfer heat directly to objects within line of sight. For the circulation of room air around the outside of the firebox, the heated surfaces of the firebox conduct heat to the air, which is then transferred back into the room by convection as the warm air rises and circulates. Conduction occurs when heat direct transfer between contacting surfaces of the firebox and the moving air.