Logarithmic Mean Temperature Difference (LMTD) Calculator

Calculate LMTD



Formula

The formula to calculate the Logarithmic Mean Temperature Difference (LMTD) is:

\[ LMTD = \frac{T2 - T1}{\ln{\left(\frac{T2}{T1}\right)}} \]

Where:

What is LMTD?

LMTD, short for Logarithmic Mean Temperature Difference, is a metric used in thermodynamics to determine the “driving” force for heat transfer in heat flow systems such as heat exchangers. For heat flow systems with a constant area and heat transfer coefficients, a larger LMTD means more heat is transferred, and a smaller LMTD means less heat is transferred.

Example Calculation

Let's assume the following values:

Using the formula to calculate the Logarithmic Mean Temperature Difference:

\[ LMTD = \frac{150 - 100}{\ln{\left(\frac{150}{100}\right)}} = \frac{50}{\ln{(1.5)}} \approx 42.84 \text{ °C} \]

The Logarithmic Mean Temperature Difference (LMTD) is approximately 42.84 °C.