What type of exchanger consists of a tube inside of another tube?

The type of exchanger that consists of a tube inside of another tube is known as a double tube heat exchanger. In this design, there are two concentric tubes: the inner tube carries one fluid, while the outer tube carries another fluid. This arrangement allows for efficient heat transfer between the two fluids due to the large surface area provided by the inner tube while minimizing the risk of mixing the fluids.

This configuration is particularly beneficial in applications where it is critical to maintain the separation of the fluids being exchanged. The simplicity of the double tube design also facilitates easier maintenance and allows for easier temperature control.

While other options like shell-and-tube and plate heat exchangers have their own unique configurations and advantages, they do not specifically feature a single tube housed within another tube. Therefore, understanding the specific structure of each type of heat exchanger is crucial in identifying the correct one.