Log Mean Temperature Difference (LMTD)

LMTD for counter-flow / parallel-flow heat exchangers. The design temperature difference that goes into Q = U·A·LMTD.

Heat transfer

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

LMTD = \frac{\Delta T_1 - \Delta T_2}{\ln(\Delta T_1 / \Delta T_2)}

Symbol	Meaning	Unit
$\Delta T_1$ , $\Delta T_2$	Temperature differences at exchanger ends	K
$LMTD$	Log-mean temperature difference	K

Source: Incropera - Fundamentals of Heat and Mass Transfer

LMTD for counter-flow / parallel-flow heat exchangers.