This model represents an instantaneously mixed volume. Potential and kinetic energy at the port are neglected, and there is no pressure drop at the ports. The volume can exchange heat through its heatPort.

The volume can be parameterized as a steady-state model or as dynamic model.

To increase the numerical robustness of the model, the constant prescribedHeatFlowRate can be set by the user. This constant only has an effect if the model has exactly two fluid ports connected, and if it is used as a steady-state model. Use the following settings:


The parameter mSenFac can be used to increase the thermal mass of this model without increasing its volume. This way, species concentrations are still calculated correctly even though the thermal mass increases. The additional thermal mass is calculated based on the density and the value of the function HeatCapacityCp of the medium state state_default.
This parameter can for instance be useful in a pipe model when the developer wants to lump the pipe thermal mass to the fluid volume. By default mSenFac = 1, hence the mass is unchanged. For higher values of mSenFac, the mass will be scaled proportionally.

Set the parameter use_C_flow = true to enable an input connector for the trace substance flow rate. This allows to directly add or subtract trace substances such as CO2 to the volume. See Buildings.Fluid.Sensors.Examples.PPM for an example.


If the model is operated in steady-state and has two fluid ports connected, then the same energy and mass balance implementation is used as in steady-state component models, i.e., the use of actualStream is not used for the properties at the port.

The implementation of these balance equations is done in the instances dynBal for the dynamic balance and steBal for the steady-state balance. Both models use the same input variables:

For the rationale of selecting different energy and mass balances, and for the use of prescribedHeatFlowRate, see the documentation of Buildings.Fluid.MixingVolumes.BaseClasses.PartialMixingVolume.

For simple models that uses this model, see Buildings.Fluid.HeatExchangers.HeaterCooler_u and Buildings.Fluid.Humidifiers.Humidifier_u.


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