Isothermal Liquid Predefined Properties (IL)

Set working fluid properties for an isothermal liquid network

Since R2020a

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Libraries:
Simscape / Fluids / Isothermal Liquid / Utilities

Description

The Isothermal Liquid Predefined Properties (IL) block sets the working fluid liquid properties of your isothermal liquid network to the properties of a predefined fluid.

You can also model dissolved air in the system as a function of pressure. To specify your own working fluid properties, use the Foundation Library Isothermal Liquid Properties (IL) block. If you do not specify a fluid, the system defaults apply. See Specify Fluid Properties for more details.

Fluid Properties Range

You can set the block to model the properties of several predefined different liquids by using the Isothermal liquid parameter.

Water

The block provides the water properties between the triple point, when the fluid temperature and pressure reach 273.160 K and 611.657 Pa, and the critical point, when the fluid temperature reaches 647.096 K. P_min is set by the triple point or the saturation pressure, whichever is greater.

Ethylene-, Propylene-, and Glycerol-Water Mixtures

The block provides the properties for ethylene-glycol, propylene-glycol, and glycerol are provided for temperatures above the solution freezing point. When you visualize properties, the displayed minimum temperature may be lower than the fluid freezing point. The block does not display updated temperatures for different mixture concentrations.

When you specify the mixture, you can define the concentration of ethylene glycol, propylene glycol, or glycerol to water by mass fraction or volume fraction by using the Concentration type parameter.

The block provides the properties for:

• Concentration by mass between 0 and 0.6 and by volume between 0 and 1 for ethylene glycol.

• Concentration by mass between 0 and 0.6 and by volume between 0.1 and 0.6 for propylene glycol.

• Concentration by mass between 0 and 0.6 for glycerol. You cannot model glycerol concentration by volume.

The block stores the properties as a function of temperature and concentration. The block maintains all properties, except for density and the thermal expansion coefficient α, as constants for a range of pressures.

Seawater

The block provides seawater properties for temperatures between 273.15 K and 393.15 K and for pressures above the system saturation pressure. The salinity concentration can range from 0 to 0.12 by mass.

The block stores the properties as tabulated data with respect to pressure and temperature. The block derives the data from the Thermophysical properties of seawater software on the MIT website.

Aviation Fuel Jet-A

The block provides properties for a general, representative fuel mixture based on Jet-A-4658 and Jet-A-3638 surrogates at temperatures between 222.22 K and 645.61 K and pressures above the saturation point.

The block stores the properties as tabulated data with respect to pressure and temperature.

Diesel Fuel

The block provides diesel properties for temperatures between 238.20 K and 690.97 K and for pressures above the saturation point.

SAE 5W-30

The block provides SAE 5W-30 properties for temperatures between 235.15 K and 473.15 K and for pressures above 0.01 MPa. The block bases the properties at the system temperature and atmospheric pressure measurements for temperatures between 29.85 °C and 74.85 °C (303 K to 348 K) and pressures between 7 MPa and 87 MPa. The block uses curve fits to define properties in extrapolated regions.

Lubricating Oils and Hydraulic Fluids

The block uses numerical approximations to calculate fluid properties for these liquids:

• SAE 30 Oil

• SAE 50 Oil

• 10W Oil

• 30W Oil

• 50W Oil

• Skydrol LD-4

• Skydrol 500B-4

• Skydrol 5

• HyJet-IVA

• Fluid MIL-F-83282

• Fluid MIL-F-5606

• Fluid MIL-F-87257

• ATF (Dexron III)

• ISO VG 22 (ESSO UNIVIS N 22)

• ISO VG 32 (ESSO UNIVIS N 32)

• ISO VG 46 (ESSO UNIVIS N 46)

• ISO VG 68

• Brake fluid DOT 3

• Brake fluid DOT 4

• Brake fluid DOT 5

The block uses the Walther equation to approximate changes in velocity, v, with respect to temperature, T

$${\log }_{10}\left({\log }_{10}\left(v+a\right)\right)=b-d{\log }_{10}\left(T\right),$$

where a, b, and d are constants that are specific to each fluid.

The block assumes that the density, ρ, changes linearly with respect to temperature,

$$\rho ={\rho }_{ref}+\alpha \left(T_{ref}-T\right),$$

where:

• α are constants that are specific to each fluid.

• ρ_ref is the fluid density at the reference temperature, T_ref.

The bulk modulus, β, is

$$\beta =\rho c^2,$$

where c is the speed of sound. The block uses c = 1460 m/s as the speed of sound in hydraulic oils.

Gasoline

The block uses the same approximations as the lubricating oils and hydraulic fluids to calculate the gasoline density and bulk modulus. In gasoline, the speed of sound is 1250 m/s.

The Vogel-Fulcher-Tammann equation calculates the fluid viscosity for gasoline,

$${\text{v=v}}_0{e}^{\frac{B}{T-T_0}},$$

where v₀, B, and T₀ are constants.

Dissolved Air

You can optionally model air dissolved into the liquid system. If you select Model air dissolution, the block models dissolution between the values of the Atmospheric pressure parameter and the Pressure at which all entrained air is dissolved parameter by using Henry's law. For more information, see Fluid Models with Entrained Air.

Visualizing Fluid Properties

To visualize the fluid density and bulk modulus in your network, right-click the Isothermal Liquid Predefined Properties (IL) block and select Fluids > Plot Fluid Properties.

Use the Reload Data button to regenerate the plot when the fluid selection or fluid parameters change.

Examples

Pressure Control Solenoid

Model, parameterize, and test a pressure control solenoid valve. This example also generates a plot of the relationship between applied solenoid force and the resulting actuator port pressure.

• Open Model

Ports

Conserving

A — Connection port

isothermal liquid

Isothermal liquid conserving port that connects the block to the network. Connect this port to any point on an isothermal liquid connection line in a block diagram. When you connect the Isothermal Liquid Predefined Properties (IL) block to a network line, the liquid properties propagate to all blocks in the circuit.

Parameters

Liquid

Isothermal liquid — Fluid choice

Water (default) | Seawater (MIT model) | Ethylene glycol and water mixture | Propylene glycol and water mixture | Glycerol and water mixture | Aviation fuel Jet-A | Diesel fuel | SAE 5W-30 | SAE 30 Oil | SAE 50 Oil | 10W Oil | 30W Oil | 50W Oil | Skydrol LD-4 | Skydrol 500B-4 | Skydrol 5 | HyJet-IVA | Fluid MIL-F-83282 | Fluid MIL-F-5606 | Fluid MIL-F-87257 | ATF (Dexron III) | ISO VG 22 (ESSO UNIVIS N 22) | ISO VG 32 (ESSO UNIVIS N 32) | ISO VG 46 (ESSO UNIVIS N 46) | ISO VG 68 | Brake fluid DOT 3 | Brake fluid DOT 4 | Brake fluid DOT 5 | Gasoline

Choice of working fluid in the system.

Note

For these fluids, the block calculates the fluid properties by interpolating experimental data:

• Water

• Seawater (MIT model)

• Ethylene glycol and water mixture

• Propylene glycol and water mixture

• Glycerol and water mixture

• Aviation fuel Jet-A

• Diesel fuel

• SAE 5W-30

For the remaining fluids, the block uses approximations to calculate the fluid properties. For these approximated fluids, the block may output unexpected results at extreme temperatures or if the fluid deviates significantly from atmospheric pressure.

Dissolved salt mass fraction (salinity) — Salt concentration

3.5e-3 (default) | positive scalar between (0, 0.12]

Concentration of salt in water by mass.

Dependencies

To enable this parameter, set Isothermal liquid to Seawater (MIT).

Concentration type — Concentration by mass or volume

Volume fraction (default) | Mass fraction

Whether the solute is measured in water by mass or volume.

Dependencies

To enable this parameter, set Isothermal liquid to:

• Ethylene glycol and water mixture.

• Propylene glycol and water mixture.

Ethylene glycol volume fraction — Ethylene glycol concentration by volume

0.1 (default) | positive scalar between (0, 1.0]

Fraction of ethylene glycol in water, by volume.

Dependencies

To enable this parameter, set Isothermal liquid to Ethylene glycol and water mixture and Concentration type to Volume fraction.

Ethylene glycol mass fraction — Ethylene glycol concentration by mass

0.1 (default) | positive scalar between (0, 0.6]

Fraction of ethylene glycol in water, by mass.

Dependencies

To enable this parameter, set Isothermal liquid to Ethylene glycol and water mixture and Concentration type to Mass fraction.

Isothermal bulk modulus at atmospheric pressure (no entrained air) — Bulk modulus

2.1791 GPa (default) | positive scalar

Solution bulk modulus at atmospheric pressure.

Dependencies

To enable this parameter, set Isothermal liquid to:

• Ethylene glycol and water mixture.

• Propylene glycol and water mixture.

• Glycerol and water mixture.

Minimum valid pressure — Lower pressure limit

0.01 (default) | positive scalar

Lower pressure limit during simulations. The Atmospheric pressure must greater than or equal to the Minimum valid pressure.

Dependencies

To enable this parameter, set Isothermal liquid to:

• Ethylene glycol and water mixture.

• Propylene glycol and water mixture.

• Glycerol and water mixture.

Propylene glycol volume fraction — Propylene glycol concentration by volume

0.1 (default) | positive scalar between [0.1, 0.6]

Fraction of propylene glycol in water, by volume.

Dependencies

To enable this parameter, set Isothermal liquid to Propylene glycol and water mixture and Concentration type to Volume fraction.

Propylene glycol mass fraction — Propylene glycol concentration by mass

0.1 (default) | positive scalar between (0, 0.6]

Fraction of propylene glycol in water, by mass.

Dependencies

To enable this parameter, set Isothermal liquid to Propylene glycol and water mixture and Concentration type to Mass fraction.

Glycerol mass fraction — Glycerol concentration by mass

0.1 (default) | positive scalar between (0, 0.6]

Fraction of glycerol in water, by mass.

Dependencies

To enable this parameter, set Isothermal liquid to Glycerol and water mixture.

System temperature — Network temperature

300 K (default) | positive scalar

Isothermal liquid network temperature.

Viscosity derating factor — Viscosity correction factor

1 (default) | positive scalar

Correction factor for fluids diverging from the clean fluid standard viscosity.

Atmospheric pressure — User-defined environmental pressure

0.101325 MPa (default) | positive scalar

Environmental pressure of the system.

Pressure below minimum valid value — Whether to notify when pressure is below the minimum valid value

Error (default) | Warning | None

Select what happens if the fluid pressure goes below the minimum valid value during simulation:

• None ― The block does not return an error if the properties go below the minimum valid value.

• Warning ― The block issues a warning, but continues the simulation.

• Error ― The block returns an error and stops the simulation.

Entrained Air

Volumetric fraction of air that is entrained at atmospheric pressure — System air entrainment at atmospheric pressure

0.005 (default) | positive scalar

Air entrainment in fluid network at atmospheric pressure.

Air polytropic index — Polytropic process exponent

1.0 (default) | positive scalar between [0, 1]

Exponent of the equation that governs the polytropic process relating fluid pressure and volume.

Air density at atmospheric condition — Air density

1.225 kg/m^3 (default) | positive scalar

Air density at the pressure defined in the Atmospheric pressure parameter.

Model air dissolution — Whether to model air entrainment

off (default) | on

Whether to account for air dissolution into the fluid network. Air dissolution into the liquid is modeled between the values of the Atmospheric pressure parameter and the Pressure at which all entrained air is dissolved parameter by Henry's Law.

Pressure at which all entrained air is dissolved — Upper pressure limit for air entrainment

3 MPa (default) | positive scalar

Upper pressure limit for air entrainment into the fluid.

Dependencies

To enable this parameter, select Model air dissolution.

References

[1] Massachusetts Institute of Technology (MIT). Thermophysical properties of seawater database. http://web.mit.edu/seawater.

[2] K.G. Nayar, M.H. Sharqawy, L.D. Banchik, J.H. Lienhard V. "Thermophysical properties of seawater: A review and new correlations that include pressure dependence." Desalination 390 (July 2016): 1-24.

[3] M.H. Sharqawy, J.H. Lienhard V, S.M. Zubair. "Thermophysical properties of seawater: A review of existing correlations and data." Desalination and Water Treatment 16, no. 1-3 (april 2010): 354-380.

[4] I.H. Bell, J. Wronski, S. Quoilin, V. Lemort. "Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp." Industrial & Engineering Chemistry Research 53, no. 6 (February 12, 2014): 2498–2508.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2020a

R2024a: New predefined fluids

The block now includes these predefined isothermal fluids:

• SAE 30 Oil

• SAE 50 Oil

• 10W Oil

• 30W Oil

• 50W Oil

• Skydrol LD-4

• Skydrol 500B-4

• Skydrol 5

• HyJet-IVA

• Fluid MIL-F-83282

• Fluid MIL-F-5606

• Fluid MIL-F-87257

• ATF (Dexron III)

• ISO VG 22 (ESSO UNIVIS N 22)

• ISO VG 32 (ESSO UNIVIS N 32)

• ISO VG 46 (ESSO UNIVIS N 46)

• ISO VG 68

• Brake fluid DOT 3

• Brake fluid DOT 4

• Brake fluid DOT 5

• Gasoline

R2024a: Pressure outside valid range parameter renamed

The Pressure outside valid range parameter is renamed to Pressure below minimum valid value for clarity. The behavior of the parameter is not changed.

R2023a: Numerical adjustments for SAE 5W-30

When the Isothermal liquid parameter is SAE 5W-30, the block includes numerical adjustments to the density, bulk modulus, thermal expansion coefficient, and specific internal energy to make the data more closely match experimental data.

R2023a: Control block behavior when fluid properties go out of range during simulation

Previously, if fluid properties went beyond the valid range during simulation, the block would return an error. You can now use the new Pressure outside valid range parameter to control the block behavior if fluid properties go out of range during simulation