A heat exchanger with the heating medium in the tubes is called?

• A. Immersion coil
• B. Shell and tube
• C. Plate heat exchanger
• D. Air heater

Answer: (A)

The heating medium flowing inside tubes points to a coil that is immersed in the liquid to be heated. This setup is known as an immersion coil. The hot fluid (steam or hot water) circulates through the coil’s tubes, transferring heat through the tube walls into the surrounding liquid in the vessel. This direct immersion method is common for heating liquids in tanks because it provides efficient heat transfer without circulating the process fluid through a separate exchanger.

The other options describe different heat exchanger concepts: a shell and tube or plate heat exchanger involves the two fluids circulating through separate passages, not a coil sitting inside the tank; an air heater is designed to heat air rather than a liquid by immersion.