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Log Mean Temperature Difference Calculator
Calculate LMTD from two positive terminal temperature differences. Choose input units and calculate one value within the stated conditions.
Inputs
Calculations run in this browser. Scientific notation such as 1.2e-3 is supported. Do not group thousands.
Result
Log mean temperature difference ΔT_lm
Enter values and select Calculate.
ΔT_lm = (ΔT₁−ΔT₂)/ln(ΔT₁/ΔT₂)
Assumptions
Required: ΔT₁,ΔT₂>0 without a temperature cross. Equal differences return their common limiting value. Heat duty, correction factors and exchanger geometry are excluded.
Displayed values are floating-point approximations. Design safety factors and unprovided error contributions are not calculated.
Formula references and credits
NaNa Lab created the code, descriptions, icons and preview images. Text, figures and code from the linked references have not been reproduced.
Physical constants: NIST / CODATA 2022. The values of μ₀ and ε₀ are measured recommendations, not exact defining constants. Values and precision notes are in the source record.
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