Performance evaluation of some tube inserts as heat transfer enhancement techniques

Different heat transfer enhancement techniques can be used successfully in the retrofit design of shell-and-tube heat exchangers that can lead to significant cost savings. Tube inserts are frequently used in such applications. Twisted tapes, wire coils, helically coiled ribbons (as tube inserts in smooth pipes), and rifled pipes have been evaluated as heat transfer enhancement techniques. To assess the benefit of using these kinds of techniques, extended performance evaluation criteria (PEC) have been implemented under different constraints. The decrease in entropy generation can be combined with the relative increase in the heat transfer rate or decrease of the heat transfer area to determine the geometrical parameters of the tubes for optimal thermodynamics performance.