LMTD for counter-flow / parallel-flow heat exchangers. The design temperature difference that goes into Q = U·A·LMTD.
Formula
$$ LMTD = \frac{\Delta T_1 - \Delta T_2}{\ln(\Delta T_1 / \Delta T_2)} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\Delta T_1$, $\Delta T_2$ | Temperature differences at exchanger ends | K | derived |
| $LMTD$ | Log-mean temperature difference | K | result |
Sources
- Incropera - Fundamentals of Heat and Mass Transfer.