What is the primary function of a heat exchanger?

• A. To cool a liquid by transferring heat from one medium to another
• B. To filter contaminants from a fluid
• C. To store thermal energy
• D. To generate electricity

Answer: (A)

Heat exchangers move heat between two fluids without letting them mix. Their main function is to transfer energy from a hot medium to a cooler one, changing the temperatures of both streams as needed. That’s why cooling a liquid by transferring its heat to another medium is the best description—the fluids stay separate, and heat flows across the boundary to achieve the desired temperature change. This differs from filtering (removing contaminants), storing thermal energy (holding heat for later use with a dedicated storage device), or generating electricity (requiring a turbine or generator to convert heat into electrical energy).