STRESSES ON ALUMINUM BRAZED PLATE FIN HEAT EXCHANGERS IN A FLOATING ENVIRONMENT

The present paper describes a study for the application of Aluminum Brazed Plate Fin Heat Exchangers (PFHE) in a floating environment. Due to the continuous movements of the ship hull a main focus is given to fatigue considerations because it is well known that aluminum does not have a distinct endurance limit. Therefore it is mandatory to base a fatigue evaluation on a design code as for example the German AD2000 Merkblatt S2 [16] which allows fatigue evaluation of aluminum. There an endurance limit of 5 million cycles is defined. On that basis two plate fin heat exchangers were analyzed focusing on accelerations due to ship motion and thermal fatigue as a secondary consequence of ship movements (liquid sloshing, unsteady flows). For the acceleration due to ship motions a value out of a concept study was taken. This value of 2.5 m/s(2) was used for acceleration in three directions for both exchangers. All calculated stresses were below the endurance limit and therefore no measures have to be taken. Thermal fatigue as secondary effect of the ship movements was analyzed as a worst case investigation for a block in shell exchanger. The resulting fatigue loads seem not to be a concern in this specific case but it is strongly recommended to carefully check any design for similar or different applications. Furthermore it is recommended generally to carefully ensure stable process conditions. Summing up all these points the application of PFHE in a floating environment has to be investigated very carefully but seems to be possible.