Fluid Library
AFT Arrow provides an AFT Standard fluid library for numerous common fluids. If the working fluid you wish to model is not in this library, you may elect to enter the fluid properties in a custom library for later reuse using the Edit Fluids panel in the Library Manager.
You can open the Edit Fluids panel from the Library menu or from the Edit Fluid list button in the Fluid panel in Analysis Setup. The Edit Fluids panel allows you to review currently defined AFT Standard and custom fluids, to change the data for custom fluids, and to enter new fluids. All AFT Standard fluid properties are assumed to be a function of temperature. Custom fluids can be a function of temperature or solids concentration.
Once you have entered a custom fluid, it will appear in the Fluids Available in Library list of the Fluid panel when User Library Fluid is selected.
Adding a Custom Fluid
You can add new fluids by clicking the Add New Fluid button on the Edit Fluids panel of the Library Manager. A number of fluid properties are required for a compressible flow analysis. There are also several optional properties.
Required Data:
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Dynamic Viscosity
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Specific Heat (at constant pressure)
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Reference Temperature/Enthalpy point
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Molecular Weight
Optional Data:
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Thermal Conductivity (required for heat transfer capabilities besides adiabatic/isothermal in pipes)
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Vapor Pressure (required if checks and warnings for saturation are desired)
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Compressibility Factor
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Critical property data points are used for some Equation of State and enthalpy models
Except for the constants and enthalpy, all properties are assumed to be functions of temperature only. The assumption can break down in systems with very large temperature changes, and should be checked by the user. These properties can be modeled with polynomials or interpolation, and features for creating curve fits from raw data are provided.
The enthalpy is a strong function of temperature but a weaker function of pressure. Frequently the pressure dependence of enthalpy can be ignored. The three enthalpy models offered by AFT Arrow allow you to choose different ways of handling the pressure dependence.
The Add New Fluid/Change Fluid Data windows offer cross-plotting of your custom curves against the curve fit data points. You can also import data from text files into these windows.
