Thermal Liquid Properties (TL)

Preset fluid properties for the simulation of a thermal liquid network

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Libraries:
Simscape / Fluids / Thermal Liquid / Utilities

Description

The Thermal Liquid Properties (TL) block sets the predefined fluid properties of a thermal liquid network. The available fluids include pure water, aqueous mixtures, diesel, aviation fuel jet A, and SAE 5W-30. You can use this block as an alternative to the Thermal Liquid Settings (TL) block. If your network does not have a liquid properties block, the liquid defaults apply.

You can set values for density, the bulk modulus and thermal expansion coefficient, the specific internal energy and specific heat, the kinematic viscosity, and the thermal conductivity. The values you can enter for each block parameter depend on the liquid that you model. If you enter a value outside the valid range for a liquid property, the model generates an error during simulation.

Data Visualization

To plot the data, open the block dialog box and, under Plots, click the Plot button next to Thermal liquid properties. When you select a fluid property from the drop-down list, the plot updates. If you change the block parameter values, you can regenerate the plot by clicking Reload Data.

Regions of Valid Fluid Properties

The thermodynamic correlations that calculate fluid properties within the Thermal Liquid Properties (TL) block define the region of valid fluid properties. When you enter a value outside the valid ranges, the model generates an error during simulation. You cannot change the valid fluid properties region for each fluid. To visualize these regions, open the block dialog box and, under Plots, click the Plot button next to Thermal liquid properties.

Water

The fluid properties of water are valid at temperatures between the triple point, 273.160 K, and the critical point, 647.096 K. They are valid at pressures between the triple point, 611.657 Pa, and the saturation pressure up to the critical point of 22.065 MPa. Water properties below the saturation point for a given temperature are not valid.

Seawater (MIT model)

The fluid properties of seawater are valid at temperatures between 273.15 K and 393.15 K. They are valid at pressures above the saturation pressure and below 12 MPa. Pressures below the saturation point for the given temperature and concentration level are not valid. Mixture concentrations can range from 0 to 0.12 on a mass-fraction basis.

Ethylene glycol and water mixture

The fluid properties of an aqueous ethylene glycol mixture are valid between temperatures that depend on the mixture concentration and the freezing point of the liquid. You set the Minimum valid pressure and Maximum valid pressure in the block dialog box. Mixture concentrations can range from 0 to 0.6 on a mass-fraction basis, or from 0 to 1 on a volume fraction basis.

Propylene glycol and water mixture

The fluid properties of an aqueous propylene glycol mixture are valid between temperatures that depend on the mixture concentration and the freezing point of the liquid. You set the values of Minimum valid pressure and Maximum valid pressure in the block dialog box. Mixture concentrations can range from 0 to 0.6 on a mass-fraction basis, or from 0 to 1 on a volume fraction basis.

Glycerol and water mixture

The fluid properties of an aqueous glycerol mixture are valid between temperatures that depend on the mixture concentration and freezing point of the liquid. You set the Minimum valid pressure and Maximum valid pressure in the block dialog box. Mixture concentrations can range from 0 to 0.6 on a mass-fraction basis. The block smooths and extrapolates data to 100 degC depending on the type of data:

Extrapolation Method for Glycerol and Water Mixture

Fluid Property	Extrapolation Method
Density	Quadratic
Thermal expansion coefficient	Linear
Specific heat	Linear
Specific internal energy	Linear
Kinematic viscosity	Exponential
Dynamic viscosity	Exponential
Prandtl number	Exponential

Aviation fuel Jet-A

The fluid properties of Jet-A fuel are valid at temperatures between 222.22 K and 645.1 K. They are valid at pressures between the saturation point and 2.51 MPa. Jet-A fuel properties below the saturation point for a given temperature are not valid.

Diesel fuel

The fluid properties of diesel fuel are valid at temperatures between 238.20 K and 690.97 K. They are valid at pressures between the saturation point and 2.29 MPa. Diesel fuel properties below the saturation point for a given temperature are not valid.

SAE 5W-30

The fluid properties of SAE 5W-30 are valid at temperatures between 235.15 K and 473.15 K. They are valid at pressures between 0.01 MPa and 100 MPa. The block smooths and extrapolates data to cover all temperatures outside 303.00 K and 348.00 K and pressures outside 7 MPa and 82 MPa depending on the type of data:

Extrapolation Method for SAE 5W-30

Fluid Property	Extrapolation Method
Density	Quadratic
Bulk Modulus	Linear
Thermal expansion coefficient	Linear
Specific heat	Linear
Thermal conductivity	Linear
Kinematic viscosity	Analytical
Dynamic viscosity	Exponential in Temperature Linear in Pressure
Prandtl number	Analytical

Calculations of Fluid Properties

The block calculates the density and expansion coefficients using block parameters when you set Thermal liquid fluid list to one of these values:

• Ethylene glycol and water mixture

• Propylene glycol and water mixture

• Glycerol and water mixture

The block calculates the temperature and pressure dependent fluid density as

$$\rho (T,p)=\rho (T)\text{exp}\left(\frac{p-p_{\text{R}}}{\beta }\right),$$

where:

• T is the network temperature.

• p is the network pressure.

• ρ is the fluid density.

• p_R is the reference pressure associated with the fluid property tables.

• ß is the isothermal bulk modulus.

The block calculates the change in fluid density with respect to temperature as

$${\left(\frac{\partial \rho (T,p)}{\partial T}\right)}_p={\left(\frac{\partial \rho (T)}{\partial T}\right)}_T\text{exp}\left(\frac{p-p_{\text{R}}}{\beta }\right).$$

The thermal expansion coefficient is calculated as:

$$\alpha (T,p)=-\frac{1}{\rho (T,p)}{\left(\frac{\partial \rho (T)}{\partial T}\right)}_T\text{exp}\left(\frac{p-p_{\text{R}}}{\beta }\right).$$

Model Entrained Air

If the value of the Volumetric fraction of entrained air in mixture at atmospheric conditions is nonzero, the thermal liquid network connected to the Thermal Liquid Properties (TL) block contains a small amount of nondissolved air. To model air dissolution, select the Model air dissolution check box. For more information, see Parameterizing Entrained Air in a Thermal Liquid.

Examples

Engine Cooling System

Model an engine cooling system with an oil cooling circuit.

• Open Model

EV Battery Thermal Management System

An Electric Vehicle (EV) battery heating-cooling system. Maintaining the battery temperature within an optimal range is important for efficient charging and discharging. The model simulates either the FTP-75 drive cycle or a fast charge cycle at different environment temperatures. A thermal liquid coolant circuit conveys heat between the battery and the heating-cooling unit. For more information on designing EV battery cooling systems, see EV Battery Cooling System Design.

• Open Live Script

Ports

Conserving

R — Thermal liquid properties

thermal liquid

Thermal liquid conserving port associated with the thermal liquid properties. Connect this port to the thermal liquid network for which you want to define the working fluid. You can connect each network to only one Thermal Liquid Properties (TL) or Thermal Liquid Settings (TL) block.

Parameters

Parameters

Thermal liquid fluid list — Working fluid to apply to thermal liquid network

Water (default) | Seawater (MIT model) | Ethylene glycol and water mixture | Propylene glycol and water mixture | Glycerol and water mixture | Diesel Fuel | Aviation fuel Jet-A | SAE 5W-30

Working fluid to apply to the connected thermal liquid network. The available fluids include pure water, aqueous mixtures, motor oils, and fuels.

Dissolved salt mass fraction (salinity) — Mass of salt divided by total mass of saline mixture

3.5e-3 (default) | positive unitless scalar valued between 0 and 1

Ratio of the mass of salt present in the saline mixture to the total mass of that mixture.

Dependencies

To enable this parameter, set Thermal liquid fluid list to Seawater (MIT model).

Concentration type — Quantity to use to define the mixture concentration

Volume fraction (default) | Mass fraction

Quantity to use to define the concentration of ethylene glycol in its aqueous mixture.

Dependencies

To enable this parameter, set Thermal liquid fluid list to Ethylene glycol and water mixture or Propylene glycol and water mixture.

Ethylene glycol volume fraction — Volume of ethylene glycol divided by volume of aqueous mixture

0.1 (default) | positive unitless scalar valued between 0 and 1

Volume of the ethylene glycol present in the aqueous mixture, divided by the total volume of that mixture.

Dependencies

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

Ethylene glycol mass fraction — Mass of ethylene glycol divided by mass of aqueous mixture

0.1 (default) | positive unitless scalar valued between 0 and 1

Mass of the ethylene glycol present in the aqueous mixture, divided by the total mass of that mixture.

Dependencies

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

Propylene glycol volume fraction — Mass of propylene glycol divided by mass of aqueous mixture

0.1 (default) | positive unitless scalar valued between 0 and 1

Volume of the propylene glycol present in the aqueous mixture, divided by the total volume of that mixture.

Dependencies

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

Propylene glycol mass fraction — Mass of propylene glycol divided by mass of aqueous mixture

0.1 (default) | positive unitless scalar valued between 0 and 1

Mass of the propylene glycol present in the aqueous mixture, divided by the total mass of that mixture.

Dependencies

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

Glycerol mass fraction — Mass of glycerol divided by mass of aqueous mixture

0.1 (default) | positive unitless scalar valued between 0 and 1

Mass of glycerol present in the aqueous mixture, divided by the total mass of that mixture.

Dependencies

To enable this parameter, set Thermal liquid fluid list to Glycerol and water mixture.

Isothermal bulk modulus — Bulk modulus of mixture at constant temperature

2.1791 GPa (default) | positive scalar with units of pressure

Bulk modulus of the aqueous mixture at constant temperature. The bulk modulus represents the change in pressure required to produce a fractional change in the fluid volume.

Dependencies

To enable this parameter, set Thermal liquid fluid list to one of these values

• Ethylene glycol and water mixture

• Propylene glycol and water mixture

• Glycerol and water mixture

Minimum valid pressure — Minimum allowed pressure for thermal liquid network

0.01 MPa (default) | positive scalar with units of pressure

Minimum pressure allowed in the thermal liquid network.

Dependencies

To enable this parameter, set Thermal liquid fluid list to one of these values:

• Ethylene glycol and water mixture

• Propylene glycol and water mixture

• Glycerol and water mixture

Maximum valid pressure — Maximum allowed pressure range for thermal liquid network

50 MPa (default) | positive scalar with units of pressure

Maximum pressure allowed in the thermal liquid network.

Dependencies

To enable this parameter, set Thermal liquid fluid list to one of these values:

• Ethylene glycol and water mixture

• Propylene glycol and water mixture

• Glycerol and water mixture

Atmospheric pressure — Absolute pressure in environment

0.101325 MPa (default) | positive scalar with units of pressure

Absolute pressure of the external environment in which the thermal liquid network runs. The default value is the standard atmospheric pressure at sea level on Earth.

Atmospheric temperature — Absolute temperature of the environment

293.15 K (default)

Absolute temperature of the environment.

Pressure and temperature outside valid range — Whether to notify when pressure or temperature are outside valid range

Error (default) | Warning | None

Whether to generate a notification if the fluid pressure or temperature exceeds the valid range during simulation:

• None ― The block does not return an error.

• 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 entrained air in mixture at atmospheric conditions — Fraction of entrained air in mixture

0.005 (default) | scalar between 0 and 1

Volumetric fraction of entrained air in the fluid and air mixture at atmospheric conditions. To model a system with no entrained air, set this parameter to 0.

Specific gas constant — Specific gas constant of entrained air

0.287 kJ/(K*kg) (default) | positive scalar

Specific gas constant of the air entrained in the fluid.

Model air dissolution — Whether to model air dissolution

off (default) | on

Whether to account for air dissolution into the fluid network:

• If you clear this parameter, the amount of entrained air is constant. The network does not model air dissolution.

• If you select this parameter, the entrained air in the network can dissolve into the liquid. The amount of dissolved air is a function of pressure.

Full dissolution pressure — Pressure at which all entrained air is dissolved

3 MPa (default) | positive scalar

Critical pressure at which all entrained air is dissolved for a specific temperature.

Dependencies

To enable this parameter, select Model air dissolution.

Plots

Thermal liquid properties — Generate thermal liquid properties plot

button

Use the Plot button to generate the thermal liquid properties plot.

References

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

[2] Nayar, Kishor T., et al. "Thermophysical Properties of Seawater: A Review and New Correlations That Include Pressure Dependence." Desalination, vol. 390, July 2016, pp. 1-24. DOI.org (Crossref), https://doi.org/10.1016.j.desal.2016.02.024

[3] Sharqawy, Mostafa H., et al. "Thermophysical Properties of Seawater: A Review of Existing Correlations and Data." Desalination and WaterTreatment, vol. 16, no. 1-3, Apr. 2010, pp. 354-80. DOI.org (Crossref), https://doi.org/10.5004/dwt.2010.1079

Extended Capabilities

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

Version History

Introduced in R2018a

R2026a: Model entrained air

The thermal liquid domain now models entrained air in the fluid flow, which is a small amount of nondissolved gas trapped in the fluid. Entrained air makes the fluid more compressible, which can reduce numerical stiffness. You can also optionally model air dissolution to allow entrained air to dissolve into the liquid.

R2023a: Numerical adjustments for SAE 5W-30

When the Thermal liquid fluid 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 and temperature outside valid range parameter to control the block behavior if fluid properties go out of range during simulation