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 set predefined fluid properties to 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 a preset alternative to the Thermal Liquid Settings (TL) block. If your network does not have a connected liquid properties block, or the liquid defaults will apply. See Specify Fluid Properties for more details

The preset fluid properties are defined in tabular form as functions of temperature and pressure. During simulation, the network properties are set by linear interpolation between data points. Tabular data for aqueous mixtures is provided for concentration by mass or volume.

All the fluid properties commonly specified in the Thermal Liquid Settings (TL) block are defined in the block. These properties include density, the bulk modulus and thermal expansion coefficient, the specific internal energy and specific heat, as well as the kinematic viscosity and thermal conductivity. The properties are valid over a limited region of temperatures and pressures specific to the fluid selected and dependent, in the cases of mixtures, on the concentration specified. Simulation is allowed within this validity region only.

Data Visualization

You can visualize the fluid properties defined in the block and the pressure and temperature regions of validity. To open the visualization utility, right-click the block and select Fluids > Plot Fluid Properties. The plot updates automatically upon selection of a fluid property from the drop-down list. Use the Reload Data button to regenerate the plot whenever the fluid selection or fluid parameters change.

Visualization of density data for a 10% glycerol aqueous mixture

Validity Regions

The validity regions are defined in the block as matrices of zeros and ones. Each row corresponds to a tabulated temperature and each column to a tabulated pressure. A zero denotes an invalid breakpoint and a one a valid breakpoint. These validity matrices are internal to the block and cannot be modified; they can only be checked (using the data visualization utility of the block).

In most cases, the validity matrices are extracted directly from the tabulated data. The glycol and glycerol mixtures pressure boundaries are not available from the data, and are obtained explicitly from block parameters. The figure below shows an example of the validity region for water. The shaded squares indicate temperature and pressure regions outside of the validity region.

Water

The properties of water are valid at temperatures above the triple-point value (273.160 K) up to the critical-point value (647.096 K). They are valid at pressures above the greater of the triple-point value (611.657 Pa) on one hand and the temperature-dependent saturation value on the other, up to the critical-point value (22.064 MPa). Pressures below the saturation point for a given temperature row are assigned a value of 0 in the validity matrix.

Seawater (MIT model)

The properties of seawater are valid at temperatures above 0°C up to 120°C (273.15 K to 393.15 K); they are valid at pressures above the saturation point up to a maximum value of 12 MPa. Pressures below the saturation point for a given temperature row (and at the specified concentration level) are assigned a value of 0 in the validity matrix. Mixture concentrations can range in value from 0 to 0.12 on a mass fraction basis.

Ethylene glycol and water mixture

The properties of an aqueous ethylene glycol mixture are valid over a temperature domain determined from the mixture concentration; they are valid at pressures within the minimum and maximum bounds specified in the block dialog box (extended horizontally to span the width of the temperature rows).

The lower temperature bound is always the lesser of the minimum temperature extracted from the available data and the freezing point of the mixture (the mixture must be in the liquid state). The upper temperature bound is always the maximum temperature extracted from the data. Mixture concentrations can range in value from 0 to 0.6 if a mass-fraction basis is used, or from 0 to 1 if a volume fraction basis is used.

Propylene glycol and water mixture

The properties of an aqueous propylene glycol mixture are valid over the temperature and pressure ranges described for the case of Ethylene glycol and water mixture. Mixture concentrations can range in value from 0 to 0.6 if a mass-fraction basis is used, or from 0.1 to 0.6 if a volume fraction basis is used.

Glycerol and water mixture

The properties of an aqueous glycerol mixture are valid over the temperature and pressure ranges as described for the case of Ethylene glycol and water mixture. Mixture concentrations can range in value from 0 to 0.6 on a mass-fraction basis. The properties are all extended to 100 degC as:

• Density — quadratic fit

• Alpha (density thermal derivative) — linear fit

• Specific heat — linear fit

• Specific internal energy — linear fit

• Kinematic viscosity — exponential fit based on the upper half of the original temperature range

• Dynamic viscosity — exponential fit based on the upper half of the original temperature range

• Prandtl number — exponential fit based on the upper half of the original temperature range

Aviation fuel Jet-A

The properties of Jet A fuel are valid at temperatures above -50.93°C up to 372.46°C (222.22 K to 645.61 K); they are valid at pressures above the saturation point up to a maximum value of 2.41 MPa. Pressures below the saturation point for a given temperature row are assigned a value of 0 in the validity matrix.

Diesel fuel

The properties of diesel fuel are valid at temperatures above -34.95°C up to 417.82°C (238.20 K to 690.97 K); they are valid at pressures above the saturation point up to a maximum value of 2.29 MPa. Pressures below the saturation point for a given temperature row are assigned a value of 0 in the validity matrix.

SAE 5W-30

The properties of SAE 5W-30 fuel derive from data that cover temperature and pressure ranges for each property. The block uses measured properties between 29.85°C and 74.85°C (303 K to 348 K) and 7 MPa and 82 MPa. The block extrapolates data outside of this region to -38°C and 200°C (235.15 K and 473.15 K) and to 0.01 MPa and 100 MPa. The way the block smooths and extrapolates the data depends on the type of data:

• Density — The block uses a quadratic fit. The block fits extrapolated regions to the bulk modulus and alpha fundamental relationships.

• Bulk modulus — The block uses fundamental relationship with density based on the density quadratic fit. The block uses linear extrapolation in the extrapolation region.

• Alpha (density thermal derivative) — The block uses the fundamental relationship with density based on density quadratic fit. The block uses linear extrapolation in the extrapolation region.

• Specific heat — The block uses linear extrapolation in the extrapolation region. There is no dependency on pressure.

• Thermal conductivity — The block uses linear extrapolation in the extrapolation region. There is no dependency on pressure.

• Kinematic viscosity — The block uses the fundamental relationship with the fits of dynamic viscosity and density.

• Dynamic viscosity — The block uses an exponential fit with temperature and a linear fit with pressure.

• Prandtl number — The block uses the fundamental relationship with the fits of specific heat, dynamic viscosity, and thermal conductivity.

Calculated Properties

The density and thermal expansion coefficients of the aqueous mixtures of glycol and glycerol compounds are obtained from the block parameters. The fluid density, with respect to pressure and temperature, is calculated 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.

where the change in fluid density is evaluated 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:

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

Examples

Engine Cooling System

Model an engine cooling system with an oil cooling circuit.

• Open Model

EV Battery Cooling System

This demo shows an Electric Vehicle (EV) battery cooling system. The battery packs are located on top of a cold plate which consists of cooling channels to direct the cooling liquid flow below the battery packs. The heat absorbed by the cooling liquid is transported to the Heating-Cooling Unit. The Heating-Cooling Unit consists of three branches to switch operating modes to cool and heat the battery. The Heater represents an electrical heater for fast heating of the batteries under low temperature conditions. The Radiator uses air-cooling and/or heating when the batteries are operated stably. The Refrigerant system is used for cooling the overheated batteries. The refrigeration cycle is represented by the amount of heat flow extracted from the cooling liquid. The system is simulated under either FTP-75 drive cycle or fast charge scenarios with different environment temperatures.

• Open Model

Ports

Conserving

R — Thermal liquid network for which to define the working fluid

thermal liquid

Node identifying the thermal liquid network for which to define the necessary fluid properties. The fluid selected in this block applies to the entire network. No other Thermal Liquid Properties (TL) or Thermal Liquid Settings (TL) block may be connected to the same network.

Parameters

Thermal liquid fluid list — Available working fluids

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

Sets the fluid properties of your liquid network. The available fluids include pure water, aqueous mixtures, motor oils, and fuels.

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

This parameter is active only when Seawater (MIT model) is selected as the working fluid.

Concentration type — Quantity in terms of which the mixture concentration is defined

Volume fraction (default) | Mass fraction

Quantity in terms of which to specify the concentration of ethylene glycol in its aqueous mixture. This parameter is active only when either Ethylene glycol and water mixture or Propylene glycol and water mixture is selected as the working fluid.

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

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

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

Dependencies

This parameter is active when Ethylene glycol and water mixture is selected as the working fluid and Volume fraction is selected as the concentration type.

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

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

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

Dependencies

This parameter is active when Ethylene glycol and water mixture is selected as the working fluid and Mass fraction is selected as the concentration type.

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

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

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

Dependencies

This parameter is active when Propylene glycol and water mixture is selected as the working fluid and Volume fraction is selected as the concentration type.

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

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

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

Dependencies

This parameter is active when Propylene glycol and water mixture is selected as the working fluid and Mass fraction is selected as the concentration type.

Isothermal bulk modulus — Measure of fluid compressibility specified 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 measures the change in pressure required to produce a fractional change in fluid volume.

Dependencies

This parameter is active when either Ethylene glycol and water mixture, Propylene glycol and water mixture, or Glycerol and water mixture is selected as the working fluid.

Minimum valid pressure — Lower bound of the allowed pressure range for the thermal liquid network

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

Lower bound of the pressure range allowed in the thermal liquid network connected to this block.

Dependencies

This parameter is active when either Ethylene glycol and water mixture, Propylene glycol and water mixture, or Glycerol and water mixture is selected as the working fluid.

Maximum valid pressure — Upper bound of the allowed pressure range for the thermal liquid network

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

Upper bound of the pressure range allowed in the thermal liquid network connected to this block.

Dependencies

This parameter is active when either Ethylene glycol and water mixture, Propylene glycol and water mixture, or Glycerol and water mixture is selected as the working fluid.

Atmospheric pressure — Absolute pressure in the environment of the thermal liquid network

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

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

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

Error (default) | Warning | None

Select what happens if the fluid pressure or temperature go beyond the valid range during simulation:

• None ― The block does not return an error if the properties go out of range.

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

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

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, Vol. 390, pp. 1-24, 2016.

[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, Vol. 16, pp. 354-380.

Extended Capabilities

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

Version History

Introduced in R2018a

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