Constant Volume Chamber (TL)
A chamber with a fixed volume of coolant and a variable number of ports.
blockType: AcausalFoundation.ThermalLiquid.Elements.ConstantVolumeChamber
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Description
Block Constant Volume Chamber (TL) simulates the accumulation of mass and energy of a coolant in a chamber of a fixed volume. The chamber can have from one to four ports, designated A, B, C, D, through which liquid can flow. The volume of liquid can exchange heat with a thermal network, for example, with a network representing the surrounding space of the chamber, through the thermal port H.
The mass of the liquid in the chamber varies depending on the density, which in a thermally conductive liquid usually depends on pressure and temperature. The liquid enters the chamber when the pressure in front of the port rises above the pressure in the chamber, and flows out when the pressure gradient reverses. The effect in the model is often to smooth out sudden pressure changes, similar to how an electric capacitor smooths out the voltage.
The flow resistance between the port and the inside of the chamber is considered negligible. Therefore, the pressure inside the chamber is equal to the pressure at the inlet.
Similarly, the thermal resistance between the thermal port and the interior of the chamber is considered negligible. The temperature inside the chamber is equal to the temperature at the heat port.
Conservation of mass
Liquid can flow in and out of the chamber through ports A, B, C and D. The volume of the chamber is fixed, but due to the compressibility of the liquid, its mass may vary depending on pressure and temperature.
The mass accumulation rate in the chamber must be exactly equal to the mass flow rate through ports A, B, C and D:
where
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— pressure inside the container;
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— temperature;
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— isothermal modulus of volumetric elasticity;
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— coefficient of isobaric thermal expansion;
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— mass flow rate of the liquid.
Energy conservation
Energy can enter and leave the chamber in two ways: by liquid flow through ports A, B, C and D and by heat flow through port H. No work is done on the liquid inside the chamber. Therefore, the rate of energy accumulation in the internal volume of the liquid should be equal to the sum of the energy flows through ports A, B, C, D and H:
where
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— enthalpy;
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— density;
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— specific heat;
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— camera volume;
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— energy flow;
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— heat flow.
Conservation of momentum
The pressure drop due to viscous friction between the individual openings and the interior of the chamber is considered negligible. Gravity and other volumetric forces can be ignored. Therefore, the pressure in the internal volume of the liquid must be equal to the pressure at ports A, B, C and D:
Assumptions and limitations
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There is a fixed volume of liquid in the chamber.
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The flow resistance between the inlet and the inside of the chamber is negligible.
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The thermal resistance between the thermal port and the interior of the chamber is negligible.
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The kinetic energy of the liquid in the chamber is negligible.
Ports
Non-directional
A — heat-conducting liquid port
heat-conducting liquid
The port of the heat-conducting liquid corresponds to the entrance to the chamber.
B — heat-conducting liquid port
heat-conducting liquid
The port of the heat-conducting liquid corresponds to the second entrance to the chamber.
Dependencies
This port is visible if the Number of port parameter is set to 2, 3 or 4.
C is the port of the heat—conducting liquid
heat-conducting liquid
The port of the heat-conducting liquid corresponds to the third entrance to the chamber.
Dependencies
This port is visible if the Number of port parameter is set to 3 or 4.
D is the port of the heat—conducting liquid
heat-conducting liquid
The port of the heat-conducting liquid corresponds to the fourth entrance to the chamber. If the camera has four inlet openings, it can be used as a junction in a cross joint.
Dependencies
This port is visible if the Number of port parameter is set to 4.
H — thermal port
warm
Through this port, the liquid in the chamber exchanges heat with the heating network.
Parameters
Chamber volume — the volume of liquid inside the chamber size:q[<br>]0.001 m^3 (default)
The volume of liquid in the chamber. This volume is constant during the simulation.
Number of ports — number of input ports in the camera:q[<br>]1 (default) | 2 | 3 | 4
The number of input ports in the camera.
The camera can have from one to four ports, designated A, B, C, D.
When the parameter value is changed, the corresponding ports are opened or hidden in the block icon.
Cross-sectional area at port A — the area of the input port A, normal to the flow directionss:q[<br>]0.01 m^2 (default)
The area of the input port A, normal to the flow direction.
Cross-sectional area at port B — the area of the input port B, normal to the flow directionss:q[<br>]0.01 m^2 (default)
The area of the input port B, normal to the flow direction.
Dependencies
It is enabled if port B is visible, that is, if the Number of ports parameter is set to 2, 3 or 4.
Cross-sectional area at port C — the area of the input port C, normal to the flow directionss:q[<br>]0.01 m^2 (default)
The area of the input port C, normal to the flow direction.
Dependencies
It is enabled if port C is visible, that is, if the Number of ports parameter is set to 3 or 4.
Cross-sectional area at port D — the area of the input port D, normal to the flow directionss:q[<br>]0.01 m^2 (default)
The area of the input port D, normal to the flow direction.
Dependencies
It is enabled if port D is visible, that is, if the Number of ports parameter is set to 4.