modelValveDiscrete
Extends from TRANSFORM.Fluid.Valves.BaseClasses.PartialTwoPortTransport (Partial element transporting fluid between two ports without storage of mass or energy).
Information
This very simple model provides a (small) pressure drop which is proportional to the flowrate if the Boolean open signal is true. Otherwise, the mass flow rate is zero. If opening_min > 0, a small leakage mass flow rate occurs when open = false.
This model can be used for simplified modelling of on-off valves, when it is not important to accurately describe the pressure loss when the valve is open. Although the medium model is not used to determine the pressure loss, it must be nevertheless be specified, so that the fluid ports can be connected to other components using the same medium model.
The model is adiabatic (no heat losses to the ambient) and neglects changes in kinetic energy from the inlet to the outlet.
In a diagram animation, the valve is shown in "green", when it is open.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.MassFlowRate | m_flow_nominal | Nominal mass flowrate at full opening=1 | |
| Modelica.Fluid.Types.HydraulicConductance | k | m_flow_nominal/dp_nominal | Hydraulic conductance at full opening=1 |
| Real | opening_min | 0 | Remaining opening if closed, causing small leakage flow |
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialTwoPort) | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b) |
| Visualization | |||
| Boolean | showDesignFlowDirection (from PartialTwoPort) | true | = false to hide the flow direction arrow |
| Boolean | showName (from PartialTwoPort) | true | = false to hide component name |
| Advanced | |||
| Medium.AbsolutePressure | dp_start (from PartialTwoPortTransport) | 1e-5 | Guess value of dp = port_a.p - port_b.p |
| Medium.MassFlowRate | m_flow_start (from PartialTwoPortTransport) | 0 | Guess value of m_flow = port_a.m_flow |
| Medium.MassFlowRate | m_flow_small (from PartialTwoPortTransport) | 1e-2 | Small mass flow rate for regularization of zero flow |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialTwoPortTransport) | true | = true, if temperatures at port_a and port_b are computed |
| Boolean | show_V_flow (from PartialTwoPortTransport) | true | = true, if volume flow rate at inflowing port is computed |
| Nominal operating point | |||
| SI.AbsolutePressure | dp_nominal | Nominal pressure drop at full opening=1 | |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TRANSFORM.Fluid.Interfaces.FluidPort_Flow | port_a (from PartialTwoPort) | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| TRANSFORM.Fluid.Interfaces.FluidPort_Flow | port_b (from PartialTwoPort) | Fluid connector b (positive design flow direction is from port_a to port_b) | |
| Modelica.Blocks.Interfaces.BooleanInput | open |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.MassFlowRate | m_flow (from PartialTwoPortTransport) | Mass flow rate in design flow direction | |
| Modelica.SIunits.Pressure | dp (from PartialTwoPortTransport) | Pressure difference between port_a and port_b (= port_a.p - port_b.p) | |
| Modelica.SIunits.VolumeFlowRate | V_flow (from PartialTwoPortTransport) | m_flow/Modelica.Fluid.Utilities.regStep(m_flow, Medium.density(state_a), Medium.density(state_b), m_flow_small) | Volume flow rate at inflowing port (positive when flow from port_a to port_b) |
| Medium.Temperature | port_a_T (from PartialTwoPortTransport) | Modelica.Fluid.Utilities.regStep(port_a.m_flow, Medium.temperature(state_a), Medium.temperature(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow)), m_flow_small) | Temperature close to port_a, if show_T = true |
| Medium.Temperature | port_b_T (from PartialTwoPortTransport) | Modelica.Fluid.Utilities.regStep(port_b.m_flow, Medium.temperature(state_b), Medium.temperature(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow)), m_flow_small) | Temperature close to port_b, if show_T = true |
Revisions
- Nov 2005 by Katja Poschlad (based on ValveLinear).