Creating a New Pure Fluid in Flownex

Is it possible to create custom pure fluids in Flownex?

This article provides the necessary steps for users to create a new pure fluid in Flownex®, where a pure fluid can be considered as either a gas or a liquid where the composition of the fluid remains the same.

HOW TO CREATE A NEW PURE FLUID IN FLOWNEX

It is possible for a user to create their own custom pure fluids in Flownex®. This can be done by following the steps below.

STEP 1: OPEN THE "CHARTS AND LOOKUP TABLES" LIBRARY

Open the Charts and Lookup Tables library by clicking on the “Charts and Lookup Tables” tab.

Figure 1: Charts and Lookup Tables Library.

STEP 2: OPEN "MATERIALS AND FLUIDS" IN THE FLOW SOLVER TREE

Expand the “Flow Solver” tree and then the “Materials and Fluids” tree in the Project Database, as shown in Figure 2.

Figure 2: Materials and Fluids Library in Project Database.

STEP 3: ADD A NEW CATEGORY

The user can right-click on “Pure Fluids” and select “Add Category”. The newly created category can be renamed by the user.

Figure 3: Creating a New Category.

STEP 4: ADD A NEW PURE FLUID

The user can create the new fluid by right-clicking on the newly added category and selecting “Add new Pure Fluid”. The newly created fluid can be renamed by the user.

Figure 4: Adding a New Pure Fluid.

STEP 5: SPECIFY THE FLUID PROPERTIES

The properties of the fluid can then be specified by right-clicking on the fluid and selecting “Edit”.

Figure 6: Editing a New Pure Fluid.

The Pure Fluid editor window, as seen in Figure 7, will appear where different properties for the fluid can be specified under the tabs at the top of the window. Under the General tab, the user can specify whether the fluid is an incompressible or compressible fluid, along with the fluid’s molar mass and critical pressure.

Figure 7: Pure Fluid Properties.

The user can specify the values for Density, Viscosity, Conductivity, Cp/Enthalpy, etc. under the specific tabs. The user can specify these properties as either Constant properties, in a Table format, an Equation, or using a Script. The different options will be described in more detail below.

Constant

The user can specify a constant value that will be used for the property, as seen in Figure 8. The property will then be fixed and will not be dependent on any pressure or temperature changes in the network.

Figure 8: Specifying Constant Fluid Properties.

Table

The user can specify property values by using a Table where the property will then be dependent on pressure and temperature. Flownex® will linearly interpolate between the specified pressures and temperatures to determine the value of the property at different conditions.

Figure 9: Specifying Fluid Properties Using a Table.

Equations

Properties can also be determined using polynomial equations. Different equations are available depending on whether a compressible or incompressible fluid is created. The property will then be determined using the equation shown and constants (a0 to an) specified by the user.

Figure 10: Specifying Fluid Properties Using an Equation.

Script

Another option that can be selected by the user is using a Script. The user can then define any relationship to calculate the property using Pressure and Temperature as input variables.

Figure 10: Specifying Fluid Properties Using a Script.

Once the properties of the fluid have been specified, the user can click on the “OK” button to save the fluid properties that have been specified.

STEP 6: ASSIGNING THE FLUID TO THE NETWORK

After the fluid has been saved, the user can assign the fluid to the network, as seen in Figure 11.

Figure 11: Assigning a Custom Pure Fluid to a Network.
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