Formula

ΔT_lm = (ΔT₁ - ΔT₂) / ln(ΔT₁ / ΔT₂)

LMTD gives the effective temperature driving force across a heat exchanger. Use the counter/parallel selection to compute the correct ΔT values.

How to use

Enter inlet/outlet temperatures for both fluids and choose flow configuration. The calculator updates instantly and shows ΔT₁, ΔT₂ and the LMTD.

Example

Counter-flow: tHotIn=150°C, tHotOut=80°C, tColdIn=30°C, tColdOut=90°C → compute ΔT₁/ΔT₂ and then LMTD.

FAQs

Q: What if ΔT₁ = ΔT₂? A: LMTD reduces to the common ΔT value. Q: Units? A: All temperatures in °C produce LMTD in °C.