Two fluids swap heat across a wall. See how the temperature gap drives the duty — and why counter-flow beats parallel-flow every time.
Heat Exchanger (LMTD)Live
counter-flow vs parallel-flow
Controls
Presets
Heat exchanger duty Q = U·A·ΔT_lm, where the log-mean temperature difference (LMTD) accounts for how the temperature gap changes along the length. Counter-flow keeps the gap larger, transferring more heat. Educational tool.
Reading this result: Counter-flow holds the temperature gap open along the whole length, giving an LMTD near 34 K — that is why it out-duties parallel-flow for the same inlet temperatures.
Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.
★ Sign in to save this setupSave your tuned setup, or drop this simulation into your own site, docs, or course page.
How it works
Heat-exchanger duty is Q = U·A·ΔT_lm. The log-mean temperature difference (LMTD) correctly averages a temperature gap that varies along the length. Counter-flow keeps the gap more uniform, so it transfers more heat than parallel-flow for the same hardware. Educational tool.
✦
Ask the AI about this model
The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this LMTD heat exchanger calculator tool really free?▾
Yes. Heat Exchanger (LMTD) runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?▾
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?▾
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?▾
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.