Getting Started


What hardware and software do I need?

Computer: All CRTech software runs in the Windows operating system on a computer meeting the minimum system requirements.

CRTech Software: Thermal Desktop® is a geometric thermal modeler that operates in a powerful CAD environment. The underlying solution engine for Thermal Desktop is SINDA/FLUINT. RadCAD® is an optional Thermal Desktop module for radiation heat transfer within the thermal model or between the model and the environment. FloCAD® is another optional Thermal Desktop module for fluid modeling. TD Direct® is a powerful finite element mesher that works operates within SpaceClaim and creates an interface with Thermal Desktop. RadCAD, FloCAD, and TD Direct are all installed with Thermal Desktop and activated with license files.

Please see the Product Selection Guide for more information, or contact our sales department.

Third Party Software: A full product version of SINDA/FLUINT (as opposed to a trial version) requires Intel Visual Fortran. Thermal Desktop operates within AutoCAD. TD Direct operates within SpaceClaim. CRTech is a reseller of all of this software, so everything can be purchased together.

License: You will need a license for each part of the software you want to enable. FloCAD, RadCAD, and TD Direct are installed with every instance of Thermal Desktop, but they are only enabled with different license files. Contact CRTech to purchase a license.


How do I install the software?

See our Installation Instructions.


What learning resources are available to me, and how do I get support?

User Manuals: CRTech products install user manuals with SINDA/FLUINT, Thermal Desktop, and TD Direct. They can be accessed through the start menu: Start > All Programs > (SindaFluint or Thermal Desktop). The TD Direct manual is included in the Thermal Desktop folder from the Start Menu.

Tutorials: The Thermal Desktop, RadCAD, FloCAD, and TD Direct User Manuals include tutorial sections. The tutorials start with the basic operations of our software and gradually increase in complexity. The necessary working files for these tutorials are installed with Thermal Desktop in the folder C:\Program Files\Cullimore and Ring\Thermal Desktop\Tutorials. To use these tutorials they will need to be copied to a location not in Program Files.

Sample Models: CRTech offers a Samples and Applications Forum providing sample problems available to registered customers and evaluators. These sample problems are examples of how to use CRTech software for specific applications.

Training Classes: We offer training classes on all of our products. It is recommended that all new users attend one of our training classes. Although based on training notes available for download, these training classes provide a significant amount of information and instruction that can't be captured in training notes. We offer standard training classes where anyone can attend, or we can also provide specific training for a single organization. For more information, see our Training page.

Topic Classes: CRTech offers a variety of free short, online, topic-based classes. These classes are slightly more advanced because they cover a single topic in more detail. These classes are announced on our website and through newsletters. Recordings and notes for prior classes are available upon request.

Recorded Videos: We have recorded several videos to help explain how to use our software.

Technical Support: If you need help, please start with the product user manuals. The Thermal Desktop manual provides information on the graphical user interface, compared to the SINDA/FLIUNT manual which provides in-depth information on the modeling details and methods. If you cannot find the information you need in the manuals, visit our user support forum. After all, your question may have already been asked and answered by another user. If your question is still unanswered, please contact the support group. Support tickets may be conveniently created and transmitted from within Thermal Desktop through the Help menu.

dispersed vs. coalesced front

Tuesday, June 26, 2018, 1-2pm PT, 4-5pm ET

This webinar describes flat-front modeling, including where it is useful and how it works. A flat-front assumption is a specialized two-phase flow method that is particularly useful in the priming (filling or re-filling with liquid) of gas-filled or evacuated lines. It also finds use in simulating the gas purging of liquid-filled lines, and in modeling vertical large-diameter piping.

Prerequisites: It is helpful to have a background in two-phase flow, and to have some previous experience with FloCAD Pipes.

Register here for this webinar

FloCAD model of a loop heat pipe

Since a significant portion of LHPs consists of simple tubing, they are more flexible and easier to integrate into thermal structures than their traditional linear cousins: constant conductance and variable conductance heat pipes (CCHPs, VCHPs). LHPs are also less constrained by orientation and able to transport more power. LHPs have been used successfully in many applications, and have become a proven tool for spacecraft thermal control systems.

However, LHPs are not simple, neither in the details of their evaporator and compensation chamber (CC) structures nor in their surprising range of behaviors. Furthermore, there are uncertainties in their performance that must be treated with safety factors and bracketing methods for design verification.

Fortunately, some of the authors of CRTech fluid analysis tools also happened to have been involved in the early days of LHP technology development, so it is no accident that Thermal Desktop ("TD") and FloCAD have the unique capabilities necessary to model LHPs. Some features are useful at a system level analysis (including preliminary design), and others are necessary to achieve a detailed level of simulation (transients, off-design, condenser gradients).

CRTech is offering a four-part webinar series on LHPs and approaches to modeling them. Each webinar is designed to be attended in the order they were presented. While the first webinar presumes little knowledge of LHPs or their analysis, for the last three webinars you are presumed to have a basic knowledge TD/FloCAD two-phase modeling.

Part 1 provides an overview of LHP operation and unique characteristics
Part 2 introduces system-level modeling of LHPs using TD/FloCAD.
Part 3 covers an important aspect of getting the right answers: back-conduction and core state variability.
Part 4 covers detailed modeling of LHPs in TD/FloCAD such that transient operations such as start-up, gravity assist, and thermostatic control can be simulated.