Chemical Reaction Engineering Module Updates

For users of the Chemical Reaction Engineering Module, COMSOL Multiphysics® version 5.6 brings new functionality for modeling reacting systems: automatic reaction balancing, predefined thermodynamic systems, and reacting pellets for transport of concentrated species. This new functionality is exemplified in new tutorials in the module's Application Library, which you can use as a starting point for your models. Learn more about these chemical reaction engineering features below.

Automatic Reaction Balancing

Typos and errors in chemical equations involving many reactants and products may be difficult to discover when defining a model. With COMSOL Multiphysics® version 5.6, the Chemical Reaction Engineering Module introduces parsing of chemical elements in order to perform stoichiometric balancing of reactions. The atomic balance ensures that the chemical elements are conserved in a chemical equation. Clicking the Balance button automatically computes the stoichiometric coefficients in order to conserve all elements. In addition, parsing of atomic elements also allows for the automatic computation of the molar masses of the chemical species (compounds).

The settings for a reaction in COMSOL Multiphysics version 5.6 with annotations for where to type the reaction and perform balancing; the reaction has not yet been balanced.
Chemical equation before clicking the Balance button.

The settings for a reaction in COMSOL Multiphysics version 5.6 with annotations for where to type the reaction and perform balancing; the reaction has been balanced.
Chemical equation after clicking the Balance button.

Predefined Thermodynamic Systems

Dry air, moist air, and water-steam are available as predefined thermodynamic systems for modeling climate control and for chemical reactions that take place in water or air. For modeling CFD, heat transfer, and acoustics applications, these thermodynamic systems can generate the corresponding materials in the Materials node. The different variants of air (dry, moist, steam) automatically define the species: nitrogen, oxygen, water, argon, carbon dioxide, neon, and helium.

The COMSOL Multiphysics Model Builder with predefined thermodynamic systems shown for dry air, moist air, and water-steam.
The three predefined systems for dry air, moist air, and water-steam.

Reacting Pellets for Concentrated Solutions

The new Reactive Pellet Bed feature provides a template for modeling transport and reactions in fixed bed reactors with bimodal pore structure. You can model, for example, fixed beds that consist of spherical pellets where the pellets themselves are porous. This yields a system with macropores found between pellets, and micropores inside of the catalyst's pellets. The transport and reactions of concentrated species in the macropores and the micropores are modeled in different coordinate systems and at different scales, but they are all connected._

A chemical reaction model showing a catalyst bed in macroscale with an inset of a pore in the microscale, where inflow and outflow are noted with arrows
The radial coordinate in the microscale, r, is defined in every point in the 3D macrosystem defined by x, y, and z. The transport and reaction equations at the microscale are solved and coupled to the transport equations in the macroscale.

The settings for the Reactive Pellet Bed feature in COMSOL Multiphysics version 5.6 with the Coordinate System Selection and Pellet Properties sections expanded.
The Reactive Pellet Bed feature provides several predefined settings for specifying reacting pellets within a fixed bed reactor. In the Settings window, shown here, you can specify the pellet shape, pellet size distribution, radius, porosity, and temperature.

New Porous Medium Feature

A new feature for handling a porous medium is available for defining the different phases: solids, fluids, and immobile fluids. In the Heat Transfer in Porous Media interface, the Porous Medium feature is used to manage the material structure with a dedicated subfeature for each phase: Fluid, Porous Matrix, and optionally, Immobile Fluids. This new workflow provides added clarity and improves the user experience. It also facilitates multiphysics couplings in porous media in a more natural way. Combined with the Moisture Transport and Porous Media Flow interfaces, the heat transfer in porous media improvements enable the modeling of nonisothermal flow and latent heat storage in porous media.

You can see this new setup in the following models:

The Porous Medium feature settings in COMSOL Multiphysics version 5.6 with the Effective conductivity options shown and Reciprocal average highlighted.
A porous material with a fluid, a solid, and an immobile fluid combined with the Porous Medium feature in the Heat Transfer in Porous Media interface. The Settings window shows the selection of the model defining the effective thermal conductivity from the different phases in the porous medium.

Revamped Porous Media Features for Transport of Diluted Species

The Transport of Diluted Species in Porous Media interface is revamped to use the new Porous Medium node. Two new domain features, the Porous Medium and the Unsaturated Porous Medium nodes, are available in the Transport of Diluted Species in Porous Media interface. You can use the new Porous Medium node for assigning material properties to the multiple phases in a porous medium. The new nodes have dedicated containers to define the properties for the liquid, gas, and porous matrix. You can see this functionality demonstrated in the Ceramic Water Filter with Activated Carbon Core tutorial model.

A closeup view of the COMSOL Multiphysics version 5.6 UI with the settings shown for Transport of Diluted Species in Porous Media and a ceramic water filter candle model in the Graphics window.
Contaminant concentration in a ceramic water filter candle.

Automatic Detection of Ideal Gas Material in Heat Transfer in Fluids

The Fluid feature, available within the various heat transfer interfaces, has been updated to take advantage of the ideal gas assumption to improve computational efficiency. The new From material option of the Fluid type list automatically detects whether the material applied on each domain selection is an ideal gas or not, and uses the relevant properties for either case. This may speed up computation when computing pressure work in compressible nonisothermal flows, for example. Since the gases available in COMSOL Multiphysics® and in the Material Library are modeled as ideal gases, many models with compressible nonisothermal flow are expected to benefit from this improvement.

A model of an LED bulb visualizing the velocity around the bulb in a color gradient from dark blue to white and the temperature in the bulb using the heat camera color table.
Temperature distribution (surface plot) and velocity (arrows and streamlines) in an LED bulb. By using the ideal gas formulation automatically, the computational time is 10% shorter in COMSOL Multiphysics® version 5.6.

New Tutorial Models

COMSOL Multiphysics® version 5.6 brings three new tutorial models to the Chemical Reaction Engineering Module.

Beer Fermentation Reactor

A model of a beer fermentation reactor cut out to reveal the fluid flow and temperature inside.
Model of a beer fermentation reactor. The model accounts for ten different chemical species, heat transfer, and fluid flow.

Application Library Title:
Download from the Application Gallery

Heat Pipe

A heat pipe model with a cutout to show the inside of the pipe.
Model of a heat pipe. The model accounts for phase transformation, heat transfer, and fluid flow.

Application Library Title:
Download from the Application Gallery

Phase Envelope

A 1D plot of the chloroform-methanol phase envelope with the dew point shown as a blue line and bubble point as a green dotted line.
Phase envelope for a nonideal chloroform/methanol mixture. First a temperature–composition diagram is constructed, highlighting an azeotrope of the mixture. Additionally, an enthalpy–composition diagram is generated.

Application Library Title:
Download from the Application Gallery