Thermal Mass
This feature models a node (one-port component) of the thermal system, at which a heat rate P is prescribed to account for heat storage:
(6-21)
where C (SI unit: J/K) is the thermal capacitance, defined as
with V the volume (SI unit: m3), ρ the density (SI unit: kg/m3), Cp the heat capacity at constant volume (SI unit: J/(kg·K)), and m the mass (SI unit: kg).
This component is similar to the Thermal Capacitor two-port component, at the difference that the thermal mass has a virtual fixed temperature node.
For a steady-state problem the temperature does not change with time and P=0.
See Theory for the Thermal Capacitor and Thermal Mass Components for details about the underlying theory.
Node Connections
Set the Node name for the thermal mass node.
Node Parameters
The thermal capacitance used in Equation 6-21 should be set in this section.
Depending on the option selected in the Specify list, different settings are required:
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With Thermal capacitance (default), set directly a value or expression for C.
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With Density and heat capacity, set values or expressions for the Volume, V, the Density, ρ, and the Heat capacity at constant volume, Cp. Select any material from the Material list to define the properties From material. For User defined enter values or expressions.
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With Mass and heat capacity, set values or expressions for the Mass, M, and the Heat capacity at constant volume, Cp. Select any material from the Material list to define Cp From material. For User defined enter a value or expression.
Initial Values
Set a value or expression for the Initial temperature, T.
Results
Select appropriate options in the Add the following to default results in order to include the following global variables (space-independent) in the default plots:
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 Heat rate 
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Temperature
Location in User Interface
Context Menus
Lumped Thermal System>Nodes>Thermal Mass
Ribbon
Physics Tab with Lumped Thermal System selected:
Global>Nodes>Thermal Mass