C&R Technologies, Inc. ("CRTech") was created in 1991 by Brent Cullimore and Steve Ring. Having supported the development of SINDA/FLUINT since the early 80's, Steve and Brent took on the task of transitioning SINDA/FLUINT from a NASA-developed code to a commercial product. They began by updating and greatly enhancing SINDA/FLUINT and by providing the first-ever graphical interface, SinapsPlus® (predecessor to Sinaps®). From there the growing team continued with the development of RadCAD®, a replacement for the long-time standard thermal radiation modeling package TRASYS. Over the years, improvements and software suite expansions continued with the introduction of Thermal Desktop®, FloCAD® and TD Direct®, always with the goal of enabling fellow thermal and fluids engineers.

As a team of thermal, fluid, and chemical engineers, we understand the needs of our customers and have the knowledge to create software to meet these needs. The result is that CRTech is a world-wide powerhouse in thermal and fluids analysis software. We are not an all-in-one analysis solution for everything from stress to dynamics because we are unwilling to make the necessary compromises. We do one thing, and we do it very well.

Our customer base of over 5000 users in over 40 countries spans a broad spectrum of industries. We are the authors of the codes we sell and support commercially with personnel devoted to customer support, marketing, sales, training, and consulting.

We know what you need, so we produce tools unique to our world.

Our Core Products are:

There may be times that you are not able to purchase our software, learn how to use it, and solve your problem within your budget and time constraints. CRTech can solve this dilemma for you. We offer a full analysis consulting service for just this problem.

We also provide training in the use of all our products. See the Training page for a description of future and past courses.

Our numerous clients span such diverse industries as aerospace, aircraft manufacturers, petrochemical, electronics, automotive, energy, medical, and others:

Air Force Institute of Technology


ATA Engineering

Ball Aerospace

Blue Origin


Brigham Young University



German Aerospace Center

Embry Riddle

General Motors


Harris Corporation

Hokkaido University

Instituto Nacional de Pesquisas Espaciais



Johns Hopkins University

L-3 Communications

Lockheed Martin


MIT Lincoln Laboratory


Montana State


Naval Research Laboratory

NEC Corporation

New Mexico State University

Northrop Grumman

Nuclear Waste Partnership



Pennsylvania State University


Southwest Research Institute

Space Systems Loral


Thales Alenia Spazio

The Aerospace Corporation

UC Berkeley


United Launch Alliance

University of Arizona

University of Colorado

University of Nagoya

US Airforce

US Army

Utah State University

Virgin Galactic


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.