modelDifferenceEnthalpyFlowRate
Sensor outputting the difference between two enthalpy flow rates
Extends from Fluid.Interfaces.PartialFourPortInterface.
Information
This model outputs the difference in enthalpy flow rate between two different streams: ΔḢ = ṁ1 h1 - ṁ2 h2. Optionally the time integral of this quantity can be output. The sensor is ideal, i.e., it does not influence the fluid.
By default
-
the parameter
tauis zero, so the specific enthalpy that is used to compute each enthalpy flow rate is computed in steady-state, - the medium is the same in both streams but the model allows for specifying two different media to represent for instance the gaseous and liquid state of the same substance.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_integrator | false | Set to true to output the time integral |
| Modelica.Units.SI.Time | tau | 0 | Time constant at nominal flow rate |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m_flow_nominal | Nominal mass flow rate | |
| Initialization | |||
| Modelica.Blocks.Types.Init | initType | Modelica.Blocks.Types.Init.InitialState | Type of initialization (InitialState and InitialOutput are identical) |
| Modelica.Units.SI.SpecificEnthalpy | h1_out_start | Medium1.specificEnthalpy_pTX(p = Medium1.p_default, T = Medium1.T_default, X = Medium1.X_default) | Initial or guess value of measured specific enthalpy |
| Modelica.Units.SI.SpecificEnthalpy | h2_out_start | Medium2.specificEnthalpy_pTX(p = Medium2.p_default, T = Medium2.T_default, X = Medium2.X_default) | Initial or guess value of measured specific enthalpy |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Advanced | |||
| Medium1.MassFlowRate | m_flow_small | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | dH_flow | Difference in enthalpy flow rate between stream 1 and 2 | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | E | Time integral of enthalpy flow rate difference between stream 1 and 2 | |
| Fluid.Sensors.EnthalpyFlowRate | senEntFlo1 | Enthalpy flow rate of fluid stream 1 | |
| Fluid.Sensors.EnthalpyFlowRate | senEntFlo2 | Enthalpy flow rate of fluid stream 2 | |
| Buildings.Controls.OBC.CDL.Reals.Subtract | dif | Compute the difference | |
| Modelica.Blocks.Continuous.Integrator | int | Time integral computation |
Revisions
-
October 8, 2020, by Antoine Gautier:
First implementation.