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.
  • Uses the Ultra engine, which is a rewritten shell-and-tube calculation engine with the same performance methods as the original Xist engine. The Ultra engine provides fast and reliable exchanger designs.
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