Thermodynamics tells you heat flows from hot to cold. But the solution manual tells you how fast . That is the difference between theory and practice.
When temperature varies with both time and position, problems become transient. The solution manual demonstrates how to navigate these time-dependent equations.
Step-by-step applications of the Log Mean Temperature Difference (LMTD) and Effectiveness-NTU methods to size or evaluate parallel-flow, counter-flow, and cross-flow exchangers. 4. Mass Transfer