Mass Flow Rate Source (TL)

Generate constant mass flow rate

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Libraries:
Simscape / Foundation Library / Thermal Liquid / Sources

Description

The Mass Flow Rate Source (TL) block represents an ideal mechanical energy source in a thermal liquid network. The source can maintain a constant mass flow rate regardless of the pressure differential. There is no flow resistance and no heat exchange with the environment. A positive mass flow rate causes the fluid to flow from port A to port B.

The energy balance at the source is a function of the energy flow rates through ports A and B and the work done on the fluid:

$${\varphi }_A+{\varphi }_B+{\varphi }_{work}=0,$$

where:

• ϕ_A is the energy flow rate into the source through port A.

• ϕ_B is the energy flow rate into the source through port B.

• ϕ_work is the isentropic work done on the fluid.

The isentropic work term is

$${\varphi }_{work}=\frac{\dot{m}\left(p_B-p_A\right)}{{\rho }_{avg}},$$

where:

• ϕ_work is the isentropic work done on the thermal liquid.

• p_A is the pressure at port A.

• p_B is the pressure at port B.

• ρ_avg is the average liquid density,

  $${\rho }_{avg}=\frac{{\rho }_A+{\rho }_B}{2}\text{.}$$

Assumptions and Limitations

• There are no irreversible losses.

• There is no heat exchange with the environment.

Examples

Optimal Pipeline Geometry for Heated Oil Transportation

Model shows the opposing effects of viscous warming and conductive cooling on the temperature of a buried pipeline segment for heated oil transportation. A requirement for these systems is for the crude oil to stay well above the pour point to provide a continuous steady flow. The system is modeled using the Thermal Liquid Foundation Library. Crude oil thermodynamic properties are stored in workspace matrices and are used to populate the Thermal Liquid Settings block mask parameters.

Open Model

Hydraulic Fluid Warming Due to Losses

Model shows how Foundation Library thermal liquid components can be used to estimate the impact of viscous losses on an actuating system's temperature over a long time scale. A pump supplies energy to the system to actuate a double-acting cylinder periodically. The pressure losses within directional valve converts the energy into heat. Heat transfer through the cylinder casing to the environment provides a heat sink.

Open Model

Ports

Conserving

A — Source inlet

thermal liquid

Thermal liquid conserving port. A positive mass flow rate causes the fluid to flow from port A to port B.

B — Source outlet

thermal liquid

Thermal liquid conserving port. A positive mass flow rate causes the fluid to flow from port A to port B.

Parameters

Power added — Select whether the source performs work

Isentropic power (default) | None

Select whether the source performs work on the fluid flow:

• Isentropic power — The source performs isentropic work on the fluid to maintain the specified mass flow rate. Use this option to represent an idealized pump or compressor and properly account for the energy input and output, especially in closed-loop systems.

• None — The source performs no work on the flow, neither adding nor removing power, regardless of the mass flow rate produced by the source. Use this option to set up the desired flow condition upstream of the system, without affecting the temperature of the flow.

Mass flow rate — Constant mass flow rate through the source

0 kg/s (default)

Desired mass flow rate of the fluid through the source.

Cross-sectional area at ports A and B — Area normal to flow path at inlet and outlet

0.01 m^2 (default)

Area normal to the direction of flow at the source inlet and outlet. The two cross-sectional areas are assumed identical.

Extended Capabilities

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

Version History

Introduced in R2013b

R2023a: Configure flow conditions without affecting temperature

The block includes the Power added parameter, which lets you specify whether the source performs work on the fluid flow. The default option, Isentropic power, is equivalent to the block behavior in previous releases. Use the new None option to set up the desired flow condition upstream of the system, without affecting the temperature of the flow.