Heat Exchanger LMTD and Effectiveness-NTU
Log-mean temperature difference, heat duty, required UA, effectiveness, NTU, and capacity-rate ratio for counter-flow or parallel-flow from four temperatures and the two flows. Per the TEMA standards and standard heat-transfer texts.
Formula and source
LMTD = (dT1 − dT2) / ln(dT1/dT2). Q = C × delta-T with C = GPM × fluid factor. UA = Q / LMTD. Effectiveness = Q / (C_min × (Th_in − Tc_in)). NTU = UA / C_min. Capacity-rate ratio Cr = C_min / C_max.
TEMA (Tubular Exchanger Manufacturers Association) standards by name; standard heat-transfer texts (Incropera, Cengel) by name.
Audience
This tile is built for hvac and the adjacent professions in the HVAC group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.