Calculation of coil type economizers

WAK Module package



Program features

The WAK program designs coil type economizers with multiple helical tube bundles. Water heaters or thermal oil heaters can be calculated. The standard medium is hot oil on the tube side and flue gas on the shell side. User-specific data for the flue gas can be entered or you may select standard compositions for typical gas , fuel, or solid fuel combustions.


Calculation of horizontal or vertical exchanger arrangement is possible. The flow pattern is either countercurrent or cocurrent. The program suggests parallel flow in coils and annulus.


  1. 2 - 14 concentric tube baskets with or without a flow directing unit 
  2. if the most inner or most outer basket touches the shell or displacement body or can be constructed with a gap
  3. gap widths at displacement body and at shell independent from each other
  4. the tube geometry and number of tubes in the coils may be freely specified.

An improved calculation of the flue gas-side heat transfer allows longitudinal pitch ratios from 1.0 on (the tubes are are narrowly coiled and welded). In the calculation, the effect of radiation from the flue gas is taken into account.

The maximum film temperature is calculated for the coil  with the lowest heat transfer coefficient and for the section with the highest temperature level.


Physical properties

Physical properties of Module Standard
Water and Steam H2O x  
(Dry) air LUFT x  
Flue gas RGAS x  
12 typical machine oils OEL x  
more than 120 thermal oils T-OIL x  
8 Heavy fuel oils and Diesel HFO x  
Free input of properties of coil-side media S-DAT X  
Refrigerants / Cooling agents FRIG   x
Interface to properties generator PROPER - for coil-side media only PROP   x
General properties module for user supplied property tables S-TAB   x

Price: 2,400 EUR plus VAT


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