How to use the heat exchanger lmtd calculator
Find the log mean temperature difference and heat duty of a heat exchanger. Enter temperature difference at end 1, temperature difference at end 2, overall heat transfer coefficient, heat transfer area in the fields above; the log mean temperature difference, heat duty are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “heat exchanger duty”, “log mean temperature difference”, “LMTD”, “calculate heat exchanger lmtd”, “find log mean temperature difference”.
Formula
Variables
- d1 — Temperature difference at end 1 (K)
- d2 — Temperature difference at end 2 (K)
- U — Overall heat transfer coefficient (W/(m²·K))
- A — Heat transfer area (m²)
Worked example
With temperature difference at end 1 = 80 K, temperature difference at end 2 = 30 K, overall heat transfer coefficient = 500 W/(m²·K), heat transfer area = 4 m², the calculator gives log mean temperature difference ≈ 50.97727 K; heat duty ≈ 101.9545 kW.
Frequently asked questions
What is the heat exchanger lmtd calculator used for?
Find the log mean temperature difference and heat duty of a heat exchanger. It helps with questions such as “heat exchanger duty”, “log mean temperature difference”, “LMTD”.
What is the formula for the heat exchanger lmtd calculation?
Log mean temperature difference (K) = (d1-d2) / ln(d1 / d2). Heat duty (kW) = U × A × [Log mean temperature difference] / 1000. Here d1 is temperature difference at end 1 (K), d2 is temperature difference at end 2 (K), U is overall heat transfer coefficient (W/(m²·K)), A is heat transfer area (m²).
What inputs do I need for the heat exchanger lmtd calculator?
You need temperature difference at end 1 in K, temperature difference at end 2 in K, overall heat transfer coefficient in W/(m²·K), heat transfer area in m². Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the heat exchanger lmtd calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the heat exchanger lmtd result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.