Inferno Thermochemistry App

Calculations

Calculations are defined for a specific process system to investigate different scenarios. Each calculation is configured and then calculated from an initial state to a final state, and the difference in relevant thermochemical properties are calculated. The app allows for one input parameter to be specified as a range input, with the calculation then performed for each step having its own initial and final states.

A calculation might be as simple as calculating the enthalpy of a component at a specific temperature, or the change in enthalpy when chemical reactions in the system occur to specified extents. Temperature can also be solved for a specified change in enthalpy, or at which a specific reaction becomes spontaneous (i.e. change in Gibbs energy is negative, changing from positive to negative). Furthermore, the extent of one chemical reaction can be solved to result in the lowest change in Gibbs energy to simulate chemical equilibrium.

The Calculation view, for a calculation as part of a process system, allows for defining the calculation in detail in terms of its name, notes, component amounts to use as initial condition, values of specified thermochemical properties, reaction extents, etc.

This page contains the basic steps to add a calculation, and then to define a calculation in detail.

Adding a new calculation to the process system

To add and start defining a new calculation, tap on the plus button next to the heading CALCULATIONS on the Process System view. A new and empty calculation is created and added to the process system. The Calculation view is displayed with with the lists of calculation details to be edited to define the calculation:

Process System view for configuring the process system.

Process System view for configuring the process system.

Calculation view created for configuring the new calculation added to the process system.

Calculation view created for configuring the new calculation added to the process system.

Layout definition of the Calculation view

The Calculation view is used to define a calculation in terms of the component amounts used as initial condition, values of specified thermochemical properties, reaction extents, etc. The Calculation view also allows for the calculation name to be edited, notes added, and a Settings button in the top right of the view to access the app settings.

The Calculation view displays the inputs to define the specific calculation as part of the current process system, with a Calculate button at the bottom to perform calculation of results.

Important to note, the units of measure for all the parameters are displayed as configured in the app settings. If the units are changed in the settings, the specified parameter values will automatically be converted.

Calculation view for configuring the calculation.

Calculation view for configuring the calculation.

The Calculation view is divided into the following sections.

CALCULATION SETUP

This section defines the basic setup of the calculation in terms of how the calculation should be performed, and values of the most important parameters.

It firstly contains a toggle switch to specify whether initial conditions are to be specified. This determines whether the initial state's temperature and gases pressure can be specified, or if would be the same as specified below for the final state in each calculation step.

The Calculation Target sections defines which parameter to be set as target in the calculation. If Temperature is selected, a value is to be entered and will be used for the final state of each calculation step, with enthalpy and other properties being calculated. If Enthalpy is selected, the temperature would be solved for the final state to achieve the specified enthalpy. The Transformation option allows for solving the temperature at which a chemical reaction with specified extent becomes spontaneous (i.e. change in Gibbs energy is zero, and changes from positive to negative). Caution should be exercised with the Transformation option, and it is recommended to first calculate the change in Gibbs energy as a function of temperature and establish an expected temperature where the change in Gibbs energy is zero.

To note, if initial conditions are specified, the Enthalpy option changes to Delta Enthalpy since a change in temperature from the initial to final state becomes possible. This option would be used to calculate the adiabatic reaction temperature of a reaction by specifying initial conditions and setting the delta enthalpy target value to zero.

The Gases Target Variable can be specified as either pressure or volume, with the one not selected and specified being calculated. To note, the app will only allow selection and entering of gas properties (pressure, volume) when the system contains gas components.

Calculation Setup section of the Calculation view.

Calculation Setup section of the Calculation view.

COMPONENT AMOUNTS

This section lists all the components selected for the process system and allows for amounts to be entered of each component for the initial state. Components are grouped according to matter state: GASES, LIQUIDS, and SOLIDS.

Next to the heading of each group of components (the matter state name), buttons provide for changing the units of the component amounts between masses or molar amounts, with the units of each being that selected in the app settings. A toggle switch, with the text Specify total?, allows for enabling specification of the total amount of the components in the matter state group. If the total amount option is selected, an additional row is added to the matter state group of components in which the total amount can be entered. Individual component amounts can still be entered, and will be used to distribute the components in the calculation to add up to the specified total.

Component Amounts section of the Calculation view.

Component Amounts section of the Calculation view.

REACTIONS

This section lists all the chemical reactions defined for the  process system, together with the extent (fraction/percentage) that each reaction are to be completed in the calculation. For each reaction, the amounts of reactant components will be converted to the products according to the stoichiometric coefficients defined by the reaction. The extent is evaluated based on the reactant with the most limiting amount, determined stoichiometrically.

The conversion of components is calculated in the order with which the chemical reactions is listed. The component amounts specified for the reactants in the first reaction will be used to generate the product amounts with the first reaction. These amounts, together with any amounts specified for the reactants of the next reaction will be used to calculate the product amounts of the next reaction, etc.

Each chemical reaction contains a toggle switch Calculate extent for equilibrium. This option can be selected for one of the reactions only in the calculation, in which case the extent is solved that would minimize the change in Gibbs energy for the current system specification in terms of having the temperature or enthalpy of the final state specified. This would then simulate chemical equilibrium, finding the final state composition with the minimum change in Gibbs energy relative to the initial state for transformation by the selected chemical reaction. If this option is selected, the Transformation option cannot also be selected in the Calculation Setup section. For the Boudouard reaction example, this equilibrium option could be used to find the equilibrium reaction extent and system composition at a specified temperature.

Reactions section of the Calculation view.

Reactions section of the Calculation view.

Changing the specified component amounts to stoichiometric reactant amounts of a chemical reaction

For a new calculation, the component amounts are all zero by default. The app contains the functionality to assist specifying stoichiometric amounts of one of the chemical reactions.

To the far right of each reaction listed on the Calculation view, a button is located. When tapped, a menu pops up from the bottom that lists options for the basis of stoichiometric amounts to be specified. When an option is selected, stoichiometric reactant amounts are set for the selected basis, and all other component amounts are set to zero.

For example, this option can be tapped next to the Boudouard reaction to show the options. The options available is a basis of 1 kg of C(s) (because the solid components are here set to mass units), or a basis of 1 mol of CO2(g) (because the gas components are here set to molar amount units). For this example a basis of 1 kg of C(s) was selected, with the app then setting the input amount of C(s) to 1 kg, and the amount of CO2(g) was stoichiometrically calculated according to the Boudouard reaction as 83.2667 mol. The amounts of all the other components (only CO(g)) are set to zero.

Calculation view with options to set reactant component amounts stoichiometrically according to a selected chemical reaction.

Calculation view with options to set reactant component amounts stoichiometrically according to a selected chemical reaction.

Calculation view with reactant component amounts set to the basis of 1 kg C(s).

Calculation view with reactant component amounts set to the basis of 1 kg C(s).

Change between single value input and entering a range of values

All input parameters (temperature, pressure, enthalpy, component amounts, reaction extents, etc.) are specified by default as single values. If the Calculate button is tapped, a single calculation is performed. 

The app allows for changing only one parameter to a range input for which the FROM and TO, and STEP  values are then specified. The app determines the number of values in the range, and the parameter value of each step. The calculation as configured is the performed for each step value.

The option to change between single value or a range of values is available by tapping on the button to the far right of each input parameter. When tapped, a popup appears to confirm the change in input type.

For the example, the Range toggle button is tapped to the right of the Temperature input parameter (currently a single input value). A popup is displayed to confirm that the input would change to a range input. When confirmed, the Temperature input cell changes to allow for FROM, TO and STEP values to be entered. Here the range is specified as 25 to 1000°C, in steps of 100°C. The same calculation will be performed a total of 11 times, calculating for temperatures of 25, 125, 225, 325, ..., etc., up to 1000°C.

Calculation view with Temperature as a single input value.

Calculation view with Temperature as a single input value.

Calculation view with a popup to confirm changing Temperature to a range input.

Calculation view with a popup to confirm changing Temperature to a range input.

Calculation view with Temperature as a range input.

Calculation view with Temperature as a range input.