Question

A furnace uses preheated air at 300°C instead of ambient air at 30°C. If fuel consumption reduces by 20%, the impact is:

• A. Higher stack temperature
• B. Lower available heat
• C. Increased efficiency
• D. More fuel required

Hint:

Preheating the air in furnaces reduces the amount of fuel required, thereby increasing the system's efficiency by lowering energy consumption for the same output.

Answer 1

The Correct Option is C

Using preheated air at a higher temperature (300°C instead of 30°C) means that the furnace requires less energy to reach the required temperature, as the air is already partially heated. This results in a reduction in fuel consumption by 20%.
This improvement leads to an increase in the overall efficiency of the furnace, as less fuel is required for the same amount of heat output. By reducing the fuel consumption, the furnace is operating more efficiently, which is a key indicator of improved performance.
Thus, the correct impact is an increased efficiency of the furnace.