Specific Dissipation Heat Exchanger (TL)

Heat exchanger parameterized by specific dissipation data for systems with thermal liquid and controlled flows

Since R2024a

• 

Libraries:
Simscape / Fluids / Heat Exchangers / Thermal Liquid

Description

The Specific Dissipation Heat Exchanger (TL) block models the cooling and heating of fluids through conduction over a thin wall. The properties of a single-phase thermal liquid are defined on the Thermal Liquid tab. The second fluid is a controlled fluid, which is specified only by the user-defined parameters on the Controlled Fluid tab. It does not receive any properties from the domain fluid network. The heat exchange between the fluids is based on the thermal liquid sensible heat.

Heat Transfer Model

Heat transfer by the simple model is based on specific dissipation:

$$Q=\xi (T_{\text{In,Th}}-T_{\text{In,C}}),$$

where:

• ξ is specific dissipation, which is a function of the mass flow rates of the thermal and controlled liquids.

• T_In,Th is the thermal liquid inlet temperature.

• T_In,C is the controlled liquid inlet temperature.

The simple model is based on linear interpolation of user-provided tabulated data and does not capture individual features of the heat exchanger.

The fluid properties that the block uses in heat transfer calculations are the average between the value at the inlet and the value in the fluid volume.

Composite Structure

The Heat Exchanger (TL) block is a composite of the Specific Dissipation Heat Exchanger Interface (TL) and Specific Dissipation Heat Transfer blocks:

Examples

Engine Cooling System

Model an engine cooling system with an oil cooling circuit.

• Open Model

House Heating System

Model a simple house heating system. The model contains a heater, a controller, and a house structure with four radiators and four rooms. Each room exchanges heat with the environment through its exterior walls, roof, and windows. Each path is simulated as a combination of a thermal convection, thermal conduction, and the thermal mass. It is assumed that heat is not transferred internally between rooms. The heater consists of a furnace, a boiler, an accumulator, and a pump to circulate hot water in the system. The controller starts admitting fuel into the furnace if the overall average temperature of rooms falls below 21 degree C and it stops if the temperature exceeds 25 degree C. The simulation calculates the heating cost and indoor temperatures.

• Open Model

Hydraulic Oil System with Thermal Control

A hydraulic oil system with a thermal control using Simscape™ Fluids™ Thermal Liquid blocks. The hydraulic oil system consists of an oil storage tank represented by the Tank (TL) block with two inlets, a pump represented by a Mass Flow Rate Source (TL) block, and pipelines represented by Pipe (TL) block.

• Open Model

Ports

Conserving

A1 — Thermal liquid port

thermal liquid

Opening for thermal liquid to enter and exit its side of the heat exchanger.

B1 — Thermal liquid port

thermal liquid

Opening for thermal liquid to enter and exit its side of the heat exchanger.

H2 — Entrance temperature of controlled fluid 2

thermal

Entrance temperature of controlled fluid 2.

Input

CP2 — Isobaric specific heat of controlled fluid

physical signal

Instantaneous value of the isobaric specific heat for the controlled fluid.

M2 — Mass flow rate of controlled fluid

physical signal

Instantaneous value of the mass flow rate of the controlled fluid.

Parameters

Heat Transfer

Thermal liquid mass flow rate vector, mdot1 — Mass flow rate of thermal liquid at each breakpoint in lookup table for specific heat dissipation table

numerical array with units of mass over time

Mass flow rate of thermal liquid at each breakpoint in the lookup table for the specific heat dissipation table. The block inter- and extrapolates the breakpoints to obtain the specific heat dissipation of the heat exchanger at any mass flow rate. Interpolation is linear and extrapolation is nearest.

The mass flow rates can be positive, zero, or negative, but they must increase monotonically from left to right. Their number must equal the number of columns in the Specific heat dissipation table parameter. If the table has m rows and n columns, the mass flow rate vector must be n elements long.

Controlled fluid mass flow rate vector, mdot2 — Mass flow rate of controlled fluid at each breakpoint in lookup table for specific heat dissipation table

numerical array with units of mass over time

Mass flow rate of controlled fluid at each breakpoint in the lookup table for the specific heat dissipation table. The block inter- and extrapolates the breakpoints to obtain the specific heat dissipation of the heat exchanger at any mass flow rate. Interpolation is linear and extrapolation is nearest.

The mass flow rates can be positive, zero, or negative, but they must increase monotonically from left to right. Their number must equal the number of columns in the Specific heat dissipation table parameter. If the table has m rows and n columns, the mass flow rate vector must be n elements long.

Specific heat dissipation table, SD(mdot1,mdot2) — Specific heat dissipation at each breakpoint in lookup table over mass flow rates of thermal liquid and controlled fluid

numerical array with units of power over temperature

Specific heat dissipation at each breakpoint in its lookup table over the mass flow rates of thermal liquid and controlled fluid. The block inter- and extrapolates the breakpoints to obtain the effectiveness at any pair of thermal liquid and controlled fluid mass flow rates. Interpolation is linear and extrapolation is nearest.

The specific heat dissipation values must be not be negative. They must align from top to bottom in order of increasing mass flow rate in the thermal liquid channel, and from left to right in order of increasing mass flow rate in the controlled fluid channel. The number of rows must equal the size of the Thermal liquid mass flow rate vector parameter, and the number of columns must equal the size of the Controlled fluid mass flow rate vector parameter.

If your heat exchanger data sheet supplies the heat transfer coefficients, multiply the provided heat transfer coefficients by the surface area to calculate the specific dissipation.

Check if violating maximum specific dissipation — Warning condition for specific heat dissipation in excess of minimum heat capacity rate

Warning (default) | None | Error

Warning condition for specific heat dissipation in excess of minimum heat capacity rate. Heat capacity rate is the product of mass flow rate and specific heat, and its minimum value is the lowest between the flows. This minimum gives the specific dissipation for a heat exchanger with maximum effectiveness and cannot be exceeded. See the Specific Dissipation Heat Transfer block for more detail.

Pressure Loss

Mass flow rate vector — Mass flow rate at each breakpoint in lookup table for pressure drop

numerical array with units of mass per unit time

Mass flow rate at each breakpoint in the lookup table for the pressure drop. The block inter- and extrapolates the breakpoints to obtain the pressure drop at any mass flow rate. Interpolation is linear and extrapolation is nearest.

The mass flow rates can be positive, zero, or negative and they can span across laminar, transient, and turbulent zones. They must, however, increase monotonically from left to right. Their number must equal the size of the Pressure drop vector parameter, with which they are to combine to complete the tabulated breakpoints.

Pressure drop vector — Pressure drop at each breakpoint in lookup table over mass flow rate

numerical array with units of pressure

Pressure drop at each breakpoint in its lookup table over the mass flow rate. The block inter- and extrapolates the breakpoints to obtain the pressure drop at any mass flow rate. Interpolation is linear and extrapolation is nearest.

The pressure drops can be positive, zero, or negative, and they can span across laminar, transient, and turbulent zones. They must, however, increase monotonically from left to right. Their number must equal the size of the Mass flow rate vector parameter, with which they are to combine to complete the tabulated breakpoints.

Reference inflow temperature — Absolute inlet temperature assumed in tabulated data

293.15 K (default) | scalar with units of temperature

Absolute temperature established at the inlet in the gathering of the tabulated pressure drops. The reference inflow temperature and pressure determine the fluid density assumed in the tabulated data. During simulation, the ratio of reference to actual fluid densities multiplies the tabulated pressure drop to obtain the actual pressure drop.

Reference inflow pressure — Absolute inlet pressure assumed in tabulated data

0.101325 MPa (default) | scalar with units of pressure

Absolute pressure established at the inlet in the gathering of the tabulated pressure drops. The reference inflow temperature and pressure determine the fluid density assumed in the tabulated data. During simulation, the ratio of reference to actual fluid densities multiplies the tabulated pressure drop to obtain the actual pressure drop.

Mass flow rate threshold for flow reversal — Upper bound of numerically smooth region for mass flow rate

1e-3 kg/s (default) | scalar with units of mass/time

Mass flow rate below which its value is numerically smoothed to avoid discontinuities known to produce simulation errors at zero flow. See the Specific Dissipation Heat Exchanger Interface (TL) block (on which the Simple Model variant is based) for detail on the calculations for the thermal liquid side of the exchanger.

Thermal liquid volume — Volume of fluid in the thermal liquid flow channel

0.01 m^3 (default) | scalar with units of length cubed

Volume of fluid in the thermal liquid flow channel.

Cross-sectional area at ports A1 and B1 — Flow area at the inlet and outlet of the flow channel

0.01 m^2 (default) | scalar with units of length squared

Flow area at the inlet and outlet of the thermal liquid flow channel. The ports are of the same size.

Effects and Initial Conditions

Enable Thermal Liquid dynamic compressibility — Setting for liquid compressibility in heat exchanger

On (default) | Off | scalar

Option to model the pressure dynamics inside the heat exchanger. Setting this parameter to Off removes the pressure derivative terms from the component energy and mass conservation equations. The pressure inside the heat exchanger is then reduced to the weighted average of the two port pressures.

Thermal Liquid nominal temperature — Temperature at nominal operating conditions

293.15 K (default) | scalar

Thermal liquid temperature at nominal operating conditions. The block uses this value to calculate the nominal density to use in the mass and energy conservation equation when dynamic compressibility is disabled.

Dependencies

To enable this parameter, clear the Enable Thermal Liquid dynamic compressibility checkbox.

Thermal Liquid nominal pressure — Pressure at nominal operating conditions

0.101325 MPa (default) | scalar

Thermal liquid pressure at nominal operating conditions. The block uses this value to calculate the nominal density to use in the mass and energy conservation equation when dynamic compressibility is disabled.

Dependencies

To enable this parameter, clear the Enable Thermal Liquid dynamic compressibility checkbox.

Thermal Liquid initial temperature — Temperature in the thermal liquid channel at the start of simulation

293.15 K (default) | scalar with units of temperature

Temperature in the thermal liquid channel at the start of simulation

Thermal Liquid initial pressure — Pressure in the thermal liquid channel at the start of simulation

0.101325 MPa (default) | scalar with units of pressure

Pressure in the thermal liquid channel at the start of simulation.

Dependencies

To enable this parameter, select Enable Thermal Liquid dynamic compressibility .

Extended Capabilities

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

Version History

Introduced in R2024a

R2024a: Models simple heat exchanger modeling option from Heat Exchanger (TL) block

Previously, the Heat Exchanger (TL) block used the Modeling option parameter to model two block variants. This parameter has been removed and the two block variants are now two separate blocks. The Specific Dissipation Heat Exchanger (TL) block uses the heat transfer model that was previously used when Modeling option was Simple model. To use the block model used when Modeling option was E-NTU Model, see the Heat Exchanger (TL) block.