Rate, simulate, and design shell-and-tube heat exchangers

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Xist® is an incremental program that contains HTRI’s latest pointwise methods based on extensive shellside and tubeside condensation, boiling, and single-phase data. The heat transfer and pressure drop correlations are continually improved as a result of our ongoing research.

As a module in Xchanger Suite®, Xist lets you quickly transfer applicable case data to other components like Xvib® or Xace®.


  • 3D incrementation calculates localized profiles for heat transfer and pressure drop.
  • Integrated tube layout tool allows complete customization of layout and is based on a full ASME mechanical design.
  • Input via hierarchical data panels or TEMA specification sheet.
  • Vibration screening warns of probable vibration problems.
  • Extensive visualization tools show exactly how the exchanger is performing.
  • Integrated physical property system eliminates requirement for additional property generation software. Xchanger Suite includes VMGThermo™, an extensive and rigorous fluid physical property generator from Virtual Materials Group, Inc.
  • Includes built-in interface to most process simulators and mechanical design software.
  • Can be embedded as a unit operation in any process simulator supporting CAPE-OPEN.
  • Both input and output can be displayed in multiple unit sets, including user-defined sets. Dynamic display of values in all unit sets.
  • Loads input files from HTFS™, Honeywell UniSim® Shell-Tube Exchanger Modeler, and Aspen Shell & Tube Exchanger™.
  • Integration with Exchanger Optimizer™ provides embedded costing features, which include fabrication, installation, and operational estimates for design cases.
Xist Geometry
Input panel (live feedback drawing) for specifying nozzle locations.

Geometry Specifications

  • All TEMA front head, rear head, and shell styles
  • Plain, low-finned, continuous-finned, and longitudinal-finned tubes
  • Twisted tape inserts and internal microfin tubes
  • Up to 24 tubepasses
  • Single-segmental, No-Tube-In-Window (NTIW), double-segmental, rod-type baffles, helical baffles, EMbaffles®, SquareOne™ baffles, and non-baffled configurations
  • Single shell, shells in series, shells in parallel, and series/parallel combinations
  • Detailed reboiler piping specification

Calculation Features

  • Rigorous heat transfer and pressure drop calculations using a 3D incrementation scheme that divides the exchanger into a large number of zones
  • Flexible process input allowing specification of known process information (temperature, weight fraction vapor, and/or flow rate) with the program calculating missing information based on energy balance
  • Three modes: rating (known duty and geometry), simulation (unknown duty and known geometry), and design (known duty and unknown geometry)
  • Automatic screening for flow-induced acoustic and mechanical tube vibration
  • Specialized calculations and procedures for kettle reboilers, flooded evaporators, thermosiphons, reflux condensers, and falling film evaporators
  • Optional specification of heat transfer coefficients and safety factors

Design Tools

Xist Design
Input and output panels for shell-and-tube exchanger design.
  • Automatic optimization of shell diameter, baffle spacing, number of tubepasses, and tube length
  • Grid design option to vary geometry over user-specified ranges and step sizes
  • Design constraints to prevent selection of undesirable designs
  • Best buildable design determined using Smart Design approach, which employs heuristics to find optimal shell size, tubepass arrangement, baffle spacing, and tube length
  • Embedded Ultra engine to generate rapid deign results
  • Smart Design used in combination with a grid approach to access a wider range of parameters such as shell or baffle type


  • Extensive set of spreadsheet-style output reports can be printed or exported to Microsoft® Excel®
  • Summary reports with overall results in one or two pages
  • Detailed reports for local profiles of all important parameters (temperature, pressure, heat transfer coefficients, heat flux, etc.)
  • Standard TEMA specification sheet
  • 2D and 3D scaled drawings provide visual confirmation of exchanger geometry, allowing for quick identification of performance issues
  • User-defined graphs for easy accessibility