# Logarithmic Mean Temperature Differential

Written by Jerry Ratzlaff. Posted in Thermodynamics

## formula

$$LMTD = \frac {T_1\;-\;T_2} {ln \frac{T_1}{T_2}} \; = \; \frac {T_1\;-\;T_2} {lnT_1\;-\;lnT_2}$$

Where:

$$LMTD$$ = logarithmic mean temperature differential

$$T_1$$ = the inlet temperature differences between the hot and cold fluids

$$T_2$$ = the outlet temperature differences between the hot and cold fluids

$$ln$$ = natural logarithm (e = 2.71828)