Two-Phase Flow

The Most Comprehensive Two-Phase Thermohydraulic Analyzer Available

CRTech's fluid modeling module was designed right from the start to handle the peculiarities of two-phase flows along with the complexities of transitioning between single-phase and two-phase. In fact, its development was initiated specifically to avoid the shortcomings of single-phase analyzers that had been retrofitted to adapt to two-phase problems.

Combined with the heat transfer capabilities that CRTech's software provides and the CAD-based interface of FloCAD® (a module of Thermal Desktop®), and the unique capabilities such as parametric analyses, optimization, calibration, and statistical design, CRTech's two-phase flow software is truly in a class by itself.

Download the Two-Phase Brochure

Recorded Videos

Two-Phase Flow CapabilitiesDepliction of Flow Regime Mapping and Slip Flow

  • Complete thermodynamics: phases appear and disappear as conditions warrant
  • Two-phase heat transfer correlations built-in or user-defined
  • Built-in options to support pool boiling
  • Two-phase pressure drop correlations built-in or user-defined
  • Automatic flow regime mapping
  • From quasi-steady homogeneous equilibrium to fully transient two-fluid modeling
  • Optional slip flow modeling (separate phasic momentum equations)
  • Optional nonequilibrium transients
    • Complete separation of phases
    • Separate phasic energy and mass equations
  • Metastable throat states in orifices and cavitating venturis
  • Flat-front modeling methods (minimal mixing of phases) for purging, priming
  • Capillary modeling tools for static or vaporizing wicks
  • Tracking of liquid surfaces in complex tanks and vessels

Two-Phase Mixture Capabilities

  • Mixtures of up to 26 liquids and/or gases
  • Optional condensible/volatile component in mixture, including effects such as diffusion-limited condensation
  • Optional dissolution of any number of gaseous solutes into any number of liquid solvents, including homogeneous nucleation modelsCondensing in the Presence of Noncondensible Gas

Sample Industries

  • Automotive (climate control, transmissions, fuel/air)
  • Electronics (liquid cooling including immersion cooling, condensation on surfaces)
  • Aerospace (thermal management, cryogenics, ECLSS)
  • Aircraft (air conditioning, fuel/air including flow within multiple fuel tank bays)
  • Energy Systems (BWR, Rankine cycle power plants)
  • Petrochemical and Pharmaceutical (gas transport, steam injection, two-phase processes)
  • Fire Safety (liquid retardant delivery)

Sample Applications

  • Condenser, evaporator, and boiler sizing and simulation
  • Vapor compression and Rankine cycle analyses, including dynamic responses
  • Throttling processes, including Joule-Thomson cooling with two-phase outlets
  • Loop heat pipe (LHP) and capillary pumped loop (CPL) design and simulation
  • Two-phase thermosyphon simulation, whether loops or counterflow
  • Integrated analysis of cryogenic systems and dewars, thermodynamic vents and vapor-cooled shields, anti-geyser lines, pressurant systems, thermally stratified tanks, and turbomachinery cool-down
  • Gas storage and distribution systems including the effects of condensation
  • Fuel/air systems, including partially filled complex vessels
  • Waterhammer and other fast transient effects including flashing, column separation, chugging and other oscillations in two-phase lines
  • Pressurized fire retardant delivery systems
  • Condensing air heat exchangers and wet air psychrometrics, including condensation on electronics
  • Fuel cells and support equipment
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.