Pharmaceutical Engineering
Heat Transfer Area Calculator
Sizes the heat-transfer surface a duty needs from A = Q ÷ (U × ΔT), and shows how that area changes with the overall coefficient.
Heat transfer area required
Enter the heat load, the temperature difference and the overall coefficient (all above 0).
Heat exchanger parameters
The duty to be transferred, the mean temperature difference driving it, and the overall coefficient.
The duty the exchanger must transfer.
Display only — see the note below.
Use the LMTD for a counter-current exchanger.
Include fouling. Typical values are in the table below.
Enter SI units
Reference tables
Typical overall coefficients and the areas real exchangers cover.
Typical U-values (W/m²K)
| Fluids | U range |
|---|---|
| Water to water | 850–1700 |
| Steam to water | 1500–4000 |
| Oil to water | 100–350 |
| Gas to gas | 10–50 |
| Condensing steam | 2000–6000 |
Exchanger types by area
| Type | Typical area |
|---|---|
| Double pipe | 0.1–2 m² |
| Shell & tube | 5–1000 m² |
| Plate & frame | 0.1–2000 m² |
| Air cooled | 10–500 m² |
| Spiral | 0.5–200 m² |
The required surface follows directly from the rate equation Q = U · A · ΔT:
A = Q / (U × ΔT)
Q is the heat load (W), U the overall heat-transfer coefficient (W/m²K) and ΔT the mean temperature difference (K or °C — the interval is the same size in both). The area is reported in m², rounded to two decimals.
U already bundles the film coefficients on both sides, the wall conduction and the fouling resistances, which is why it — not the metal — usually decides the size of the exchanger.
Common questions
The mean temperature difference across the exchanger. For counter-current or co-current flow that is the log mean temperature difference (LMTD), not the difference at the inlet. Using the inlet difference will undersize the exchanger.
Area is inversely proportional to U, so halving the coefficient doubles the surface needed. The chart shows this for your duty — it is the reason fouling is treated so seriously in plant operation.
Not directly. The calculation is done in SI throughout and the selector only relabels the ΔT field, so convert first: 1 BTU/h = 0.2931 W.
No. Shell-and-tube exchangers with multiple passes need an F correction factor applied to the LMTD. This tool gives the clean counter-current sizing, which is the usual starting point.
Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy