In this problem, we design a shell and tube heat exchanger with multiple tubes that make multiple passes through the shell. Specifically, we find how long each tube pass must be for a given required heat load.

Heat exchanger problems typically have one of two potential main goals: (a) find the heat transferred between two fluids, OR (b) find the area needed to achieve a required target heat transfer between two fluids. In this example, we go through a systematic process to find the area required for shell and tube heat exchangers with multiple tube basses using the effectiveness-NTU method. We then use this required area to find the length of each tube pass. I believe that understanding this process will allow you to solve any heat exchanger problem.