Heat Exchanger — LMTD & Surface Area

The duty of a steam-heated stream, its log mean temperature difference, the area needed and the steam consumed.

Unit system

Inputs

Process fluid flow

Inlet temperature

Outlet temperature

Specific heat of the fluid

Steam pressure (absolute)

Overall heat transfer coefficientFouling allowance (fraction of clean U)

A clean-surface calculation stops being enough once it fouls. 0.80–0.90 is typical.

Surface area required

11.56m²

Steam consumption

2,296kg/h

Heat duty	1,360 kW
Log mean temperature difference	92.33 K
Arithmetic mean (for comparison)	96.11 K
Steam (saturation) temperature	143.6 °C
U used (W/m²·K)	1,275
Temperature approach	The temperature approach is reasonable

The steam side condenses at CONSTANT temperature (saturated steam). With superheated steam the inlet zone is dry and transfers poorly; the real area needed is somewhat larger.
The log mean is used. The arithmetic mean is shown for comparison — as the two ends diverge the gap widens and the arithmetic figure undersizes the exchanger.

A PDF carrying the inputs, results, assumptions and the source. A one-time code is sent to your address.

Results are for engineering pre-assessment and are not a product selection commitment. Final responsibility rests with the user.