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Heat Exchanger Sizing Estimator
Heat Exchanger Sizing Estimator gives a preliminary area; the U value you assumed carries most of the uncertainty in it.
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Math & Science
Heat Exchanger Sizing Estimator
Frontend preview — no upload or external service.
Required area
A 150 kW duty with an LMTD of 42.3 K at U = 850 gives about 4.2 square metres — before any fouling allowance, which typically adds a meaningful margin.
How the Heat Exchanger Sizing Estimator works
- Enter the duty and the four stream temperatures.
- Choose the flow arrangement — counter-current gives a larger temperature difference and therefore less area for the same duty.
- Add a fouling allowance and treat the result as preliminary. Selection needs manufacturer data and a thermal design review.
The method
Required area follows from duty, the log mean temperature difference and the overall heat transfer coefficient.
A = Q / (U x LMTD)
Counter-current flow produces a higher LMTD than co-current for the same terminal temperatures, which is why it needs less area.
FAQ
Why is counter-current better?
Because it maintains a larger temperature difference along the exchanger, giving a higher LMTD and less area for the same duty. Co-current also cannot cool the hot stream below the cold outlet temperature.
Where does the U value come from?
Manufacturer data or published ranges for the fluid pair and exchanger type. It varies by an order of magnitude between a gas-to-gas and a liquid-to-liquid service, and it is the largest uncertainty here.
Is this enough to specify an exchanger?
No. This is preliminary sizing. Real selection needs pressure drop, fouling factors, mechanical design and manufacturer thermal software, and it is engineering work rather than a calculation.
How we compare
| Feature | Online Tool Store | A graphing calculator | A stats package |
|---|---|---|---|
| LMTD calculated | ✓ | ✗ | ✓ |
| Flow arrangement | ✓ | ✗ | ✓ |
| No sign-up | ✓ | ✓ | ✗ |
| Nothing uploaded | ✓ | ✗ | ✗ |
Heat Exchanger Sizing Estimator gives a preliminary area; the U value you assumed carries most of the uncertainty in it.