Reacting Flows

Steam Methane Reformer for Syngas

Adding heat and steam to methane (CH4) results in syngas: a mixture of carbon monoxide (CO) and hydrogen (H2). This process can be used to create hydrogen for use in fuel cells. Alternatively, the syngas can be used as feedstock for the production of liquid fuels using the Fischer-Tropsch or Mobil processes. These pathways are important for development of biofuels (ethanol and bio-diesel from biomass) and other fuels and fuel oils as part of coal-to-liquid (CTL) and natural gas to liquid (GTL) refining.

SINDA/FLUINT (via Thermal Desktop® with FloCAD®) offers important functionality for the design and simulation of such systems, including:

  • Equilibrium reactions, finite-rate kinetics (“reacting flows”), or both within one system
  • Detailed analysis of heat transfer and heat exchange equipment for concurrent design of realistic reformer geometries
  • Inclusion of the entire process (e.g., steam generation)
  • Ability to resolve fast time scales for stability investigations and evaluations of control strategies
  • Orders of magnitude faster solutions than CFD, enabling sizing and sensitivity studies

A set of thermohydraulic models is available that focus on a plug-flow reactor (PFR) arrangement for a simplified methane steam reformer. The models are available in FloCAD format, and include:

  • Validation against other tools and methods
  • Demonstration of finite-rate kinetics (reacting flows) using Arrhenius-type coefficients
  • Demonstration of equilibrium chemistry co-solved with thermal/fluid equations
  • Demonstration of steady-state and fast transient solutions (e.g., control time scales)
  • Use of chemical equilibrium software for generation of fluid properties, including “equilibrium fluids”
  • Discussion of methods for including coke (carbon) formation

Click here to fetch the Methane Reforming Example from our User Forum

See also: Flow Battery Electrochemical Example

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.