Abstract:

ESDU 97007 introduces a computer program, ENTRANS (see ESDU 00041 for guidance on the use of this program), which generates approximate designs and cost estimates for shell-and-tube exchangers with plain tubes and a range of tube insert types, operating within ranges of tubeside pressure drop. New correlations were developed from published data for the estimation of tubeside heat transfer and pressure drop of single-phase Newtonian fluids. The following types of tube insert are considered: twisted tapes (high and low twist ratios), helically-coiled wires, wire matrix inserts (high and low matrix density), static mixers and core tubes. ESDU 97007 provides a practical guide to the benefits of tube inserts in and illustrates how those benefits can be evaluated rapidly using ENTRANS. ESDU 97007 concentrates mainly on the use of tube inserts in new equipment, but guidance is given on the benefits of their use to improve the performance of existing exchangers. ENTRANS can be used to investigate the effects of tube inserts on a number of factors including area reduction, tube pass reduction, reduction in the number of shells and the effective use of pressure drop. Since ENTRANS provides predictions of the film temperature at the tube wall, it can also be used to assess fouling mitigation in thermally-controlled fouling situations. The full design methodology, including the new correlations, is provided in ESDU 97007 and is illustrated by six worked examples, in which design geometries are selected on the basis of least budget cost. ENTRANS runs under Windows '95 or higher and makes full use of Windows graphical facilities to present design data in both graphical and tabular forms.