Xist | HTRI

Design, rate, and simulate shell-and-tube heat exchangers

A fully incremental program, Xist® contains HTRI’s latest pointwise methods based on extensive shellside and tubeside condensation, boiling, and single-phase data. As part of our ongoing research program, we continually improve and extend the heat transfer and pressure drop correlations in our software. And because it is part of Xchanger Suite®, Xist lets you quickly transfer applicable case data to other components like Xvib® or Xace®.

Xist is the industry standard for designing, rating, and simulating shell-and-tube exchangers.


  • 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.
  • Xist integrates with other engineering tools such as process simulators and mechanical design software, and CAPE-OPEN compliance ensures the broadest range of compatibility with other process simulation and physical property software.
  • Both input and output support multiple unit sets, and custom unit sets can be defined.
  • Xist loads input files from HTFS™, Honeywell’s UniSim® Shell-Tube Exchanger Modeler, and Aspen Shell & Tube Exchanger.

Geometry Specifications

Xist 2D Tube Layout
  • 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 unbaffled 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 performed using a 3D incrementation scheme to divide the exchanger into a large number of zones
  • Flexible process input that allows specification of known process information (temperature, weight fraction vapor, and/or flowrate) 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

  • Automatic optimization of shell diameter, baffle spacing, and number of tubepasses
  • Grid design option to vary geometry over user-specified ranges and step sizes
  • Design constraints to prevent selection of undesirable designs
  • Design grid to keep all alternative designs at your fingertips

Output Reports

Xist Kettle Report
  • Extensive set of spreadsheet-style output reports that 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
  • Selectable font sizes to make reports easy to view
  • Customizable unit sets that can be changed dynamically as you work

Graphic Visualization

Xist 3D Graph
  • 2D and 3D scaled drawings provide visual confirmation of exchanger geometry
  • 2D and 3D plots of local performance variables allow you to quickly spot any performance issues such as an internal temperature pinch
  • A tube layout drawing illustrating exact tube placements is also available in input for user-specified layouts
  • The setting plan drawing provides important exchanger dimensions