modelPartialModularCompressors

Base model for all modular compressor models

Information

This is a base model for modular compressors that are used, for example, in close-loop systems like heat pumps or chillers.

Definitions needed for completion

Three definitions need to be added by an extending class using this component:

Redecleration of the model modCom.
Redecleration of the model modCon.
Connection of modCom[i].port_b with port_b.

The latter provides the possibility to add further components (e.g. sensors or pipes) located at the compressors' outlets.

Modeling approaches

This base model mainly consists of two sub-models and, therefore, please checkout these models for further information of underlying modeling approaches:

Parameters

Type	Name	Default	Description
General › Modular approach
Integer	nCom	1	Number of compressors in parallel
Compressors › Geometry
Modelica.Units.SI.Volume[nCom]	VDis	fill(13e-6, nCom)	Displacement volume of the compressor
Modelica.Units.SI.Efficiency[nCom]	epsRef	fill(0.04, nCom)	Ratio of the real and the ideal displacement volume
Modelica.Units.SI.Diameter[nCom]	diameterInl	fill(12e-3, nCom)	Diameter of the pipe at compressor's inlet
Modelica.Units.SI.Diameter[nCom]	diameterOut	fill(8e-3, nCom)	Diameter of the pipe at compressor's outlet
Compressors › Compressor's characterisitcs
Modelica.Units.SI.Frequency[nCom]	rotSpeMax	fill(120, nCom)	Maximal rotational speed executable by the compressor
Real[nCom]	piPreMax	fill(15, nCom)	Maximal pressure ratio executable by the compressor
Compressors › Transient behaviour
Boolean[nCom]	useInpFil	fill(true, nCom)	= true, if transient behaviour of rotational speed is computed
Modelica.Units.SI.Time[nCom]	risTim	fill(0.5, nCom)	Time until rotational speed reaches 99.6 % of its set value
Controller › Base setup
Boolean	useExt	true	= true, if external signal is used instead of internal controllers
Modelica.Blocks.Types.SimpleController[nCom]	controllerType	fill(Modelica.Blocks.Types.SimpleController.PID, nCom)	Type of controller
Boolean[nCom]	reverseAction	fill(false, nCom)	= true, if medium flow rate is throttled through cooling coil controller
AixLib.Types.Reset[nCom]	reset	fill(AixLib.Types.Reset.Disabled, nCom)	Type of controller output reset
Controller › PID setup
Real[nCom]	k	fill(1, nCom)	Gain of controller
Modelica.Units.SI.Time[nCom]	Ti	fill(0.5, nCom)	Time constant of integrator block
Real[nCom]	Ni	fill(0.9, nCom)	Ni*Ti is time constant of anti-windup compensation
Modelica.Units.SI.Time[nCom]	Td	fill(0.1, nCom)	Time constant of derivative block
Real[nCom]	Nd	fill(10, nCom)	The higher Nd, the more ideal the derivative block
Controller › Weighting and limits
Real[nCom]	wp	fill(1, nCom)	Set-point weight for Proportional block (0..1)
Real[nCom]	wd	fill(0, nCom)	Set-point weight for Derivative block (0..1)
Real[nCom]	yMax	fill(1, nCom)	Upper limit of output
Real[nCom]	yMin	fill(0, nCom)	Lower limit of output
Pressure and heat losses › Pressure losses - General
Real[nCom]	zetInl	{((1/0.59 - 1)^2 + (1 - (diameterInl[i]/0.066)^2))*(1 - (diameterInl[i]/0.066)^2) for i in 1:nCom}	Pressure loss factor at compressor's inlet for flow of port_a -> port_b
Real[nCom]	zetOut	{((1/0.59 - 1)^2 + (1 - (diameterOut[i]/0.1122)^2))*(1 - (diameterOut[i]/0.1122)^2) for i in 1:nCom}	Pressure loss factor at compressor's outlet for flow of port_a -> port_b
Pressure and heat losses › Pressure losses - Advanced
Boolean[nCom]	from_dp	fill(false, nCom)	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean[nCom]	homotopyInitialization	fill(true, nCom)	= true, use homotopy method for initialisation
Boolean[nCom]	linearized	fill(false, nCom)	= true, use linear relation between m_flow and dp for any flow rate
Pressure and heat losses › Heat losses - General
Utilities.Types.HeatTransferModels[nCom]	heaTraMod	fill(Utilities.Types.HeatTransferModels.Simplified, nCom)	Choose heat transfer model for heat losses at compressor's inlet and outlet
Pressure and heat losses › Heat losses - Geometry
Modelica.Units.SI.Mass[nCom]	mWal	fill(2.5, nCom)	Mass of the fictitious wall
Modelica.Units.SI.SpecificHeatCapacity[nCom]	cpWal	fill(450, nCom)	Specific heat capacity of the fictitious wall
Pressure and heat losses › Heat losses - Thermal conductances
Modelica.Units.SI.ThermalConductance[nCom]	kAMeaInl	fill(25, nCom)	Effective mean thermal conductance between medium and fictitious wall at inlet
Modelica.Units.SI.ThermalConductance[nCom]	kAMeaOut	fill(35, nCom)	Effective mean thermal conductance between medium and fictitious wall at outlet
Modelica.Units.SI.ThermalConductance[nCom]	kAMeaAmb	fill(10, nCom)	Effective mean thermal conductance coefficient between fictitious wall and ambient
Pressure and heat losses › Heat losses - Initialisation
Boolean[nCom]	iniTWal0	fill(true, nCom)	= true, if wall is initialised at fixed temperature; Otherwise, steady state initialisation
Modelica.Units.SI.Temperature[nCom]	TWal0	fill(293.15, nCom)	Temperature of wall at initialisation
Advanced › General
Modelica.Units.SI.PressureDifference	dp_start	-20e5	Guess value of compressor's dp = port_a.p - port_b.p
Medium.MassFlowRate	m_flow_start	0.5*m_flow_nominal	Guess value of compressor's m_flow = port_a.m_flowr
Medium.MassFlowRate	m_flow_small	1e-6*m_flow_nominal	Small mass flow rate for regularization of compressor's zero flow
Modelica.Units.SI.MassFlowRate	m_flow_nominal	0.1	Nominal mass flow rate
Advanced › Diagnostics
Boolean	show_T	false	= true, if compressor's temperatures at port_a and port_b are computed
Boolean	show_V_flow	false	= true, if compressor's volume flow rate at inflowing port is computed
Boolean	show_staEff	false	= true, if thermodynamic states and efficiencies are computed
Boolean	show_qua	false	= true, if vapour qualities are computed
Boolean	show_parCom	true	= true, if compressors' input parameters are shown in results
Boolean	show_parCon	true	= true, if controller's input parameters are shown in results
Advanced › Initialisation
Modelica.Units.SI.Frequency[nCom]	rotSpe0	fill(60, nCom)	Compressor's rotational spped at initialisation
Modelica.Units.SI.AbsolutePressure[nCom]	pInl0	fill(3e5, nCom)	Pressure at compressor's inlet at initialisation
Modelica.Units.SI.Temperature[nCom]	TInl0	fill(283.15, nCom)	Temperature at compressor's inlet at initialisation
Advanced › Initialisation Controller
Modelica.Blocks.Types.Init[nCom]	initType	fill(Modelica.Blocks.Types.Init.InitialState, nCom)	Init: (1: no init, 2: steady state, 3: initial state, 4: initial output)
Real[nCom]	xi_start	fill(0, nCom)	Initial or guess value value for integrator output (= integrator state)
Real[nCom]	xd_start	fill(0, nCom)	Initial or guess value for state of derivative block
Real[nCom]	y_start	fill(0, nCom)	Initial value of output
Assumptions
Boolean	allowFlowReversal	true	= false to simplify equations, assuming, but not enforcing, no flow reversal

Connectors

Type	Name	Description
Modelica.Fluid.Interfaces.FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
Modelica.Fluid.Interfaces.FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b[nCom]	heatPort	Heat port for compressors' heat losses
Controls.Interfaces.ModularHeatPumpControlBus	dataBus	Connector that contains all relevant control signals

Components

Type	Name	Default	Description
SimpleCompressor[nCom]	modCom		Array of compressor models in parallel
ModularController	modCon		Model of internal controller

Name	Description
Medium
SimpleCompressor
EngineEfficiency
VolumetricEfficiency
IsentropicEfficiency
ModularController

Revisions

October 20, 2017, by Mirko Engelpracht:
First implementation (see issue 467).