CRTech Blog


May 21, 2018

This is the third post of a three-part blog on two-phase heat transport devices. It was supposed to be the final part, but if I get an inkling (and don’t retire first) perhaps I will continue with oscillating pipes or vapor chambers. If I do retire, it has been nice getting to know all of you...

March 11, 2018

Brent Cullimore

To say that Pythagoras, who lived over 2500 years ago, would be astounded by what I just did in his honor says nothing. I mean, let’s face it: he’d be astounded by kale chips, boomerangs, and tubas.

So I didn’t do it for him. I didn’t do it for...

November 03, 2017

Brent Cullimore

More than once, I got into an argument with a boss in the 80s. And I almost never had a boss who was a thermal engineer during that decade. They never knew what to do with us thermal people. Systems? Power? Materials? Propulsion? Avionics? Been...

October 03, 2017

Brent Cullimore

I don’t mean “blood and guts” metaphorically. But I don’t mean it literally either. Best to call it analytic “blood and guts.” Plus, we’ll skip the guts for now, so you can relax.

And as you’ll see, I could have called this post “City...

June 30, 2017
Heat Pipes: aka Magic Pipes

Jane Baumann

In my previous blog on thermosiphons, I introduced a multipart blog on two-phase heat transport devices. With this blog, I would like to introduce you to heat pipes (sometimes written...

February 01, 2017

Tim Panczak

I pulled into the parking lot of a small print shop in an industrial-looking area in Dublin, Ireland. I looked back at the one lane bridge I had just crossed. It was an ordinary looking bridge spanning a small canal and a rail line. I walked to the bridge,...

December 22, 2016

Brent Cullimore

It might be apparent by now that I get bothered by silly or strange things. But what’s the point of even having a pet peeve if you can’t enjoy it?

Thermally stratified tanks bother me.  Fill a tank partially full of cryogenic liquid, leave it...

September 15, 2016

Jane Baumann

My husband and I have been lucky to have two wonderful human children, one who is a mechanical engineer living and working in California and the other is in her last year of college (opting not to be an engineer). My husband is Jim Harris, a mechanism...

August 26, 2016

Doug Bell

If, like me, you are a fan of the sitcom The Big Bang Theory, you may have heard the Spherical Chicken joke in the episode “The Cooper-Hofstadter Polarization:”

There's this farmer, and he has these chickens, but...

July 29, 2016

Brent Cullimore

The field of positive psychology is devoted to making so-called “normal people” happier. A key observation is that people tend to be happiest when they are in a state called...


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.