Interface Overview

The workspace has four areas:

• the menu bar along the top: File (New, Open…, Save…, Exit), Edit (Undo, Redo), Examples, View (light or dark theme) and Help (the interactive tutorial and these docs);
• the Navigator on the left, a tree of the model's parts (drag its right edge to resize it);
• the central panel, which shows whichever Navigator item is selected;
• a docked editor on the right, which opens when you click a sub-item: a component, an adsorbent, a bed layer or a cycle step. The Results plot docks in the same place when you work in the Solver.

Each modelling item in the Navigator carries a status mark: a green tick when its inputs are complete, a red cross when something is missing or inconsistent. Hover the mark to see the problem. While a run is in progress the editors are locked, so the model cannot change under the solver.

The Navigator lists the items roughly in the order you build a model:

1. System Information: name and describe the simulation.
2. Fluid Package: choose the gas components.
3. Adsorbents: define the adsorbent materials (isotherms, kinetics, heats of adsorption).
4. Column Properties: the column geometry, energy balance, void spaces, wall and the packed layers.
5. Cycle Design: the sequence of steps and their boundary conditions, cyclic steady state, initial conditions, step connections and KPI configuration.
6. Global Variables: named variables and expressions for use in any field.
7. Solver: run the simulation, its settings, plots, KPIs and experimental data.

followed by the study tools, which run variants of the deck: Parametric Study, Optimisation and Parameterisation.

System Information

Title, Description and Author, saved with the file. The equations the model solves are documented on the engine's site: governing equations.

Fluid Package

Choose the gas components from the list of available components; the names are CoolProp fluid names. The mixing rules for the gas-phase properties are described in Equation of State.

Below the component list, two drop-downs set where the gas properties come from:

• Gas heat capacity: Ideal gas Cp(T) (the default; each component's ideal-gas heat capacity from its NASA 7-coefficient polynomial, evaluated at the local gas temperature) or User defined, a molar heat capacity per component in J/(mol·K).
• Gas viscosity: CoolProp (the default; each component's viscosity from a fit to CoolProp's values, mixed by mole fraction) or User defined, one mixture viscosity in Pa·s used in every cell.

User-defined values reproduce models that use fixed gas properties, such as 30.7 J/(mol·K) and 1.72 × 10⁻⁵ Pa·s; see constant gas heat capacity and viscosity.

Click a component under Fluid Package in the Navigator to open it. The docked editor shows its Lennard-Jones parameters (characteristic energy and length, which feed the binary-diffusion calculation used by the transport correlations).

Below them, Gas heat capacity shows which mode the deck uses, the ideal-gas $C_p(T)$ equation, the component's polynomial coefficients for each temperature range with the range limits and the source (NASA Technical Memorandum 4513, McBride, Gordon and Reno, 1993), and a plot of $C_p(T)$ over the range the polynomial covers. Outside that range the engine uses the value at the nearer limit. A component without a polynomial (hexane) keeps the CoolProp value at the initial-condition pressure and temperature, and the window says so. In User defined mode the window also shows the deck's constant for the component and draws it on the plot beside the $C_p(T)$ curve for comparison; the constant itself is edited under Fluid Package. See the equation of state for how the engine uses the heat capacities.

The adsorbed-phase heat capacity is set separately, on Column Properties → Energy Balance; see the energy balance.

Adsorbents

The deck's own library of adsorbent materials. + Add adsorbent creates a new one, and Adsorbent library… opens the curated, cited library so you can add a published material. Click a material (in the panel or under Adsorbents in the Navigator) to edit it in the docked editor:

• Material properties: solid/particle density $\rho_s$, specific heat capacity, thermal conductivity and particle void fraction $\epsilon_p$.
• Mixture model, on the Isotherms tab, says how the material's components share its surface. Independent evaluates each component's isotherm on its own at its partial pressure. Extended (competitive) uses the competitive isotherm models, which couple the components through a shared denominator. IAST predicts the mixture loadings from each component's pure isotherm by Ideal Adsorbed Solution Theory, so the components can use different models and no mixture data are needed. Each mode lists only the isotherm models that fit it. Switching modes moves each component to the matching model where one exists (Dual Site Langmuir and Extended Dual Site Langmuir, for example), keeping its parameters; a model with no match stays, with a note under it. An existing deck shows the mode its models imply.
• Per component: the Isotherm model and its parameters, with an isotherm plot; the Isosteric heat of adsorption; and the Rate model with its mass-transfer Coefficient model. Each model picker has a collapsible box showing the selected model's equation (isotherms, kinetic models).

Materials are defined once and then referenced, by mass fraction, from the packed layers, so the same material can be reused across layers.

Column Properties

The vessel and how it is packed, on four tabs:

• Geometry: the Column shape (cylinder, square or rectangle) and its dimensions, the Ambient temperature, and the bed diagram with + Add layer, ↑ Up, ↓ Down and Delete buttons for the layers.
• Energy Balance: non-isothermal or isothermal, the Thermal equilibrium model (LTE or LTNE), the adsorbed-phase heat capacity and the heat-of-adsorption convention (isosteric, internal energy, or −ΔU + RT at the local temperature).
• Void Spaces: optional lumped bottom and top void regions (dead volume at each end of the column), each with a Volume and a Resistance coefficient.
• Wall: the wall Material (a preset, or Custom with your own density, heat capacity and conductivity), Thickness and the Wall temperature boundary condition; see the wall energy balance.

A layer

Click a layer (on the bed diagram or under Column Properties in the Navigator) to open its Layer Properties, in three tabs:

• Layer: the Layer name, the Adsorbent, Length, Bed voidage $\epsilon_b$, Particle diameter and Number of cells (the finite-volume resolution).
• Momentum model: the pressure-drop model (Ergun or Darcy), with its equation under the picker.
• Transport model: the four transport correlations, Axial dispersion, Heat dispersion, Internal HTC and External HTC, each with the selected correlation's equation under its picker (transport correlations).

Number of cells sets the spatial resolution. More cells sharpen concentration and thermal fronts but slow the solver. Start modest (20–50) while building a model, then refine and confirm the results no longer change; see Numerics.

Cycle Design

A canvas of the cycle's steps plus five tabs: Cycle Data (number of cycles, step timing, the list of steps), Cyclic Steady State, Initial Conditions, Interacting Steps (connections between steps) and KPI Configuration. Click a step to open its Step Properties, with Top, Bottom and Energy Sources tabs. See Building a Cycle, Boundary Conditions, Connecting Beds, Cyclic Steady State and Performance Metrics.

Global Variables

A table of named variables (name, type, expression, value, description) that any numeric field can refer to. Most fields also accept units in square brackets, such as 10 [bar] or 25 [degC]. See Global Variables, Expressions and Units.

Solver

A toolbar with Run (or Cancel while running), a progress bar and the status, and six tabs: Solver Log, Solver Settings, Warnings (which run warnings are reported), Plotter Options, Performance Indicators and Experimental Data. After a run, the status says how many warnings it gave; they are in the Solver Log. The Results plot docks on the right. See Running the Solver, Plotting Results, Performance Metrics and Experimental Data.

Study tools

• Parametric Study: sweep up to four parameters and record every KPI of the tracked components, with the variants run in parallel.
• Optimisation: find the parameters that maximise or minimise a KPI (or a weighted sum of KPIs), with optional constraints.
• Parameterisation: fit deck parameters to experimental data.

The study tools can be opened directly with /workspace?tool=parametric-study, optimisation or parameterisation.