Is shell and tube a double pipe heat exchanger?

A shell and tube heat exchanger is not the same as a double pipe heat exchanger.

A shell and tube heat exchanger has a shell that encloses multiple tubes. The fluids flow through the shell and the tubes, respectively, to effect heat transfer. It offers a larger surface area and more complex design for efficient heat exchange.

On the other hand, a double pipe heat exchanger consists of two pipes, one within the other, with the fluids flowing in opposite directions or in a countercurrent manner. It is a relatively simpler design compared to a shell and tube exchanger.

So, while both are types of heat exchangers, they have distinct characteristics and applications.