Log Mean Temperature Difference (LMTD)

The mean driving temperature difference in a heat exchanger, calculated as LMTD = (ΔT₁ − ΔT₂) / ln(ΔT₁ / ΔT₂), where ΔT₁ and ΔT₂ are the temperature differences at each end of the unit. It is the basis of the sizing equation Q = k · A · LMTD.