Question: A tubular heat exchanger with plug flow in the tube has steam at a constant temperature on the shell side. The system is initially at steady state with no temperature driving force, and the steam is introduced in a step to the shell.
(a) Determine the tube outlet temperature as a function of time. This will require analyzing a distributed-parameter model.
(b) Formulate a lumped-parameter model that would give an approximate result for the tube outlet temperature.