Modelica.Fluid.Machines

Information

Package Content

Name	Description
SweptVolume	varying cylindric volume depending on the position of the piston
Pump	Centrifugal pump with mechanical connector for the shaft
ControlledPump	Centrifugal pump with ideally controlled mass flow rate
PrescribedPump	Centrifugal pump with ideally controlled speed
BaseClasses	Base classes used in the Machines package (only of interest to build new component models)

Modelica.Fluid.Machines.SweptVolume

Information

Mixing volume with varying size. The size of the volume is given by:

• cross sectional piston area
• piston stroke given by the flange position s
• clearance (volume at flange position = 0)

Losses are neglected. The shaft power is completely converted into mechanical work on the fluid.

The flange position has to be equal or greater than zero. Otherwise the simulation stops. The force of the flange results from the pressure difference between medium and ambient pressure and the cross sectional piston area. For using the component, a top level instance of the ambient model with the inner attribute is needed.

The pressure at both fluid ports equals the medium pressure in the volume. No suction nor discharge valve is included in the model.

The thermal port is directly connected to the medium. The temperature of the thermal port equals the medium temperature. The heat capacity of the cylinder and the piston are not includes in the model.

Parameters

Name	Description
pistonCrossArea	cross sectional area of piston [m2]
clearance	remaining volume at zero piston stroke [m3]
replaceable package Medium	Medium in the component
fluidVolume	Volume [m3]
Ports
use_portsData	= false to neglect pressure loss and kinetic energy
portsData[if use_portsData then nPorts else 0]	Data of inlet/outlet ports
Assumptions
Dynamics
energyDynamics	Formulation of energy balance
massDynamics	Formulation of mass balance
Heat transfer
use_HeatTransfer	= true to use the HeatTransfer model
replaceable model HeatTransfer	Wall heat transfer
Initialization
p_start	Start value of pressure [Pa]
use_T_start	= true, use T_start, otherwise h_start
T_start	Start value of temperature [K]
h_start	Start value of specific enthalpy [J/kg]
X_start[Medium.nX]	Start value of mass fractions m_i/m [kg/kg]
C_start[Medium.nC]	Start value of trace substances
Advanced
Port properties
m_flow_nominal	Nominal value for mass flow rates in ports [kg/s]
m_flow_small	Regularization range at zero mass flow rate [kg/s]
use_Re	= true, if turbulent region is defined by Re, otherwise by m_flow_small

Connectors

Name	Description
ports[nPorts]	Fluid inlets and outlets
heatPort
flange	translation flange for piston

Modelica.Fluid.Machines.Pump

Information

This model describes a centrifugal pump (or a group of nParallel pumps) with a mechanical rotational connector for the shaft, to be used when the pump drive has to be modelled explicitly. In the case of nParallel pumps, the mechanical connector is relative to a single pump.

The model extends PartialPump

Parameters

Name	Description
replaceable package Medium	Medium in the component
Characteristics
nParallel	Number of pumps in parallel
replaceable function flowCharacteristic	Head vs. V_flow characteristic at nominal speed and density
N_nominal	Nominal rotational speed for flow characteristic [1/min]
rho_nominal	Nominal fluid density for characteristic [kg/m3]
use_powerCharacteristic	Use powerCharacteristic (vs. efficiencyCharacteristic)
replaceable function powerCharacteristic	Power consumption vs. V_flow at nominal speed and density
replaceable function efficiencyCharacteristic	Efficiency vs. V_flow at nominal speed and density
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
checkValve	= true to prevent reverse flow
V	Volume inside the pump [m3]
Dynamics
energyDynamics	Formulation of energy balance
massDynamics	Formulation of mass balance
Heat transfer
use_HeatTransfer	= true to use a HeatTransfer model, e.g., for a housing
replaceable model HeatTransfer	Wall heat transfer
Initialization
p_a_start	Guess value for inlet pressure [Pa]
p_b_start	Guess value for outlet pressure [Pa]
m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
use_T_start	= true, use T_start, otherwise h_start
T_start	Start value of temperature [K]
h_start	Start value of specific enthalpy [J/kg]
X_start[Medium.nX]	Start value of mass fractions m_i/m [kg/kg]
C_start[Medium.nC]	Start value of trace substances
Advanced
Diagnostics
replaceable model Monitoring	Optional pump monitoring

Connectors

Name	Description
port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
heatPort
shaft

Modelica.Fluid.Machines.ControlledPump

Information

This model describes a centrifugal pump (or a group of nParallel pumps) with ideally controlled mass flow rate or pressure.

Nominal values are used to predefine an exemplary pump characteristics and to define the operation of the pump. The input connectors m_flow_set or p_set can optionally be enabled to provide time varying set points.

Use this model if the pump characteristics is of secondary interest. The actual characteristics can be configured later on for the appropriate rotational speed N. Then the model can be replaced with a Pump with rotational shaft or with a PrescribedPump.

Parameters

Name	Description
replaceable package Medium	Medium in the component
p_a_nominal	Nominal inlet pressure for predefined pump characteristics [Pa]
p_b_nominal	Nominal outlet pressure, fixed if not control_m_flow and not use_p_set [Pa]
m_flow_nominal	Nominal mass flow rate, fixed if control_m_flow and not use_m_flow_set [kg/s]
control_m_flow	= false to control outlet pressure port_b.p instead of m_flow
use_m_flow_set	= true to use input signal m_flow_set instead of m_flow_nominal
use_p_set	= true to use input signal p_set instead of p_b_nominal
Characteristics
nParallel	Number of pumps in parallel
replaceable function flowCharacteristic	Head vs. V_flow characteristic at nominal speed and density
N_nominal	Nominal rotational speed for flow characteristic [1/min]
rho_nominal	Nominal fluid density for characteristic [kg/m3]
use_powerCharacteristic	Use powerCharacteristic (vs. efficiencyCharacteristic)
replaceable function powerCharacteristic	Power consumption vs. V_flow at nominal speed and density
replaceable function efficiencyCharacteristic	Efficiency vs. V_flow at nominal speed and density
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
checkValve	= true to prevent reverse flow
V	Volume inside the pump [m3]
Dynamics
energyDynamics	Formulation of energy balance
massDynamics	Formulation of mass balance
Heat transfer
use_HeatTransfer	= true to use a HeatTransfer model, e.g., for a housing
replaceable model HeatTransfer	Wall heat transfer
Initialization
p_a_start	Guess value for inlet pressure [Pa]
p_b_start	Guess value for outlet pressure [Pa]
m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
use_T_start	= true, use T_start, otherwise h_start
T_start	Start value of temperature [K]
h_start	Start value of specific enthalpy [J/kg]
X_start[Medium.nX]	Start value of mass fractions m_i/m [kg/kg]
C_start[Medium.nC]	Start value of trace substances
Advanced
Diagnostics
replaceable model Monitoring	Optional pump monitoring

Connectors

Name	Description
port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
heatPort
m_flow_set	Prescribed mass flow rate
p_set	Prescribed outlet pressure
Characteristics
replaceable function flowCharacteristic	Head vs. V_flow characteristic at nominal speed and density

Modelica.Fluid.Machines.PrescribedPump

Information

This model describes a centrifugal pump (or a group of nParallel pumps) with prescribed speed, either fixed or provided by an external signal.

The model extends PartialPump

If the N_in input connector is wired, it provides rotational speed of the pumps (rpm); otherwise, a constant rotational speed equal to n_const (which can be different from N_nominal) is assumed.

Parameters

Name	Description
replaceable package Medium	Medium in the component
use_N_in	Get the rotational speed from the input connector
N_const	Constant rotational speed [1/min]
Characteristics
nParallel	Number of pumps in parallel
replaceable function flowCharacteristic	Head vs. V_flow characteristic at nominal speed and density
N_nominal	Nominal rotational speed for flow characteristic [1/min]
rho_nominal	Nominal fluid density for characteristic [kg/m3]
use_powerCharacteristic	Use powerCharacteristic (vs. efficiencyCharacteristic)
replaceable function powerCharacteristic	Power consumption vs. V_flow at nominal speed and density
replaceable function efficiencyCharacteristic	Efficiency vs. V_flow at nominal speed and density
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
checkValve	= true to prevent reverse flow
V	Volume inside the pump [m3]
Dynamics
energyDynamics	Formulation of energy balance
massDynamics	Formulation of mass balance
Heat transfer
use_HeatTransfer	= true to use a HeatTransfer model, e.g., for a housing
replaceable model HeatTransfer	Wall heat transfer
Initialization
p_a_start	Guess value for inlet pressure [Pa]
p_b_start	Guess value for outlet pressure [Pa]
m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
use_T_start	= true, use T_start, otherwise h_start
T_start	Start value of temperature [K]
h_start	Start value of specific enthalpy [J/kg]
X_start[Medium.nX]	Start value of mass fractions m_i/m [kg/kg]
C_start[Medium.nC]	Start value of trace substances
Advanced
Diagnostics
replaceable model Monitoring	Optional pump monitoring

Connectors

Name	Description
port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
heatPort
N_in	Prescribed rotational speed [1/min]