Question

The principle of waste heat recovery that involves transferring heat from exhaust gases to the incoming air is:

• A. Combustion
• B. Recuperation
• C. Regeneration
• D. Condensation

Hint:

Recuperation uses a continuous heat exchanger to recover waste heat from exhaust gases and improve system efficiency—no moving thermal mass involved.

Answer 1

The Correct Option is B

Step 1: Recuperation is a method of waste heat recovery in which heat from hot exhaust gases is transferred to incoming air or fluid using a heat exchanger. This process improves thermal efficiency by preheating the working fluid before it enters the main heating process.
Step 2: Recuperators are typically used in industrial furnaces, boilers, and combustion systems to reduce fuel consumption and emissions. The heat exchange is continuous and occurs through a solid barrier separating the hot and cold fluids.
Why the other options are incorrect:

• (A) Combustion is a chemical reaction, not a heat recovery method.
• (C) Regeneration also involves heat recovery but typically stores heat temporarily in a thermal mass (like a ceramic bed), then releases it to incoming air in cycles.
• (D) Condensation relates to phase change and is not used in this context.