Heat exchanger thermal design

Rated design, not catalogue selection

An exchanger picked from a supplier's software is sized to the supplier's assumptions about fouling, allowable pressure drop and margin. When the unit underperforms, the assumptions are what you argue about. We produce an independent rated design first, then use it as the technical basis for the enquiry.

Scope

• Shell-and-tube exchangers to TEMA, with type selection justified
• Thermosiphon and kettle reboilers, including circulation checks
• Overhead and vent condensers, with non-condensable handling
• Falling film and forced circulation evaporators
• Plate and spiral units where fouling or approach temperature demands them
• Air-cooled exchangers and site ambient design conditions
• Vibration, pressure drop and fouling margin checks

Where designs usually go wrong

Three recurring causes: a fouling factor copied from a textbook rather than derived from the service, a two-phase pressure drop that was never checked against the available driving head, and a temperature approach that looked economical on paper and left no margin for a summer ambient. All three are cheap to catch at design stage and expensive to discover at commissioning.

Deliverable

A rated datasheet, the thermal design output file, and a specification suitable for issuing to fabricators for competitive quotation.