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THE CALCULATORS

Logarithmic Mean Temperature Difference (LMTD)

Calculates the representative temperature driving force for heat exchange between two process streams, used in the design and rating of heat exchangers.

📖 Need the theory? Read the methodology, assumptions, and equations in the full reference guide.
Read Logarithmic Mean Temperature Difference (LMTD) Guide →

1. Define Input Parameters

2. Engineering Output

Heat duty (Q)
- W
Cold outlet temperature (T_c_out)
- °C
Delta T1 (Delta_T1)
- K
Delta T2 (Delta_T2)
- K
Logarithmic Mean Temperature Difference (Delta_T_lm)
- K
Required heat-transfer area (A)
- m²

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Context & Assumptions

LMTD is essential for sizing heat exchangers by providing a single, rigorously averaged temperature difference. It ensures the overall heat-transfer coefficient can be treated as constant, simplifying the design equation Q = U A ΔT_lm.

Understand the Engineering Principles

Review the step-by-step derivations, typical industrial limits, and scale-up rules.

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