Design, rate, and simulate air coolers and economizers

A fully incremental program, Xace®contains HTRI’s latest pointwise methods based on extensive airside and tubeside experimental data. The heat transfer and pressure drop correlations are continually improved as a result of our ongoing research program.

And as part of HTRI Xchanger Suite®, Xace lets you quickly transfer applicable case data to other components like Xist® or Xhpe®. Xace is the industry standard for designing, rating, and simulating air-cooled exchangers and economizers.


  • Xace models virtually any bundle arrangement.
  • 3D incrementation calculates localized profiles for heat transfer and pressure drop.
  • Detailed output reports provide overall and localized results.
  • 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.
  • Xace 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.

Geometry Specifications

Xace Bundle Layout
  • Forced/Induced draft, A-frame, and no fan configurations
  • Horizontal, vertical, and inclined tubes
  • Up to nine different tube geometries per bundle
  • High-finned, low-finned, continuous-finned, stud-finned, and plain tubes
  • Twisted tape and microfin tubeside enhancements
  • Staggered and inline arrangements with any combination of transverse and longitudinal pitch
  • Up to 99 tuberows per bundle
  • Automatic or user-specified bundle layouts
  • Single bundle, multiple bays, bundles in parallel, and multiple bundles/services options
  • Split-pass headers with up to 24 tubepasses in each tuberow

Calculation Features

Multiple Service Diagram
  • 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 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)
  • Forced and natural draft calculations
  • Effects of gray gas radiation can be switched on/off
  • Effects of airside flow and temperature maldistribution
  • Integrated vendor-supplied fan selection software
  • Choice of HTRI research-based methods or ESCOA methods for high-finned tubes

Design Tools

  • Automatic optimization of tuberows, bundle width, tubepasses, and airside face velocity
  • 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

  • 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 API 661/ISO 13706-style specification sheet
  • Selectable font sizes to make reports easy to view
  • Customizable unit sets that can be changed dynamically as you work

Graphic Visualiztion

Xace 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
  • Bundle layout drawing illustrating exact tube placement, including tubepass and tube type