Buildings.Fluid.CHPs.OrganicRankine.Validation

Collection of validation models

Information

This package contains validation models for the classes in Buildings.Fluid.CHPs.OrganicRankine.

Note that most validation models contain simple input data which may not be realistic, but for which the correct output can be obtained through an analytic solution. The examples plot various outputs, which have been verified against these solutions. These model outputs are stored as reference data and used for continuous validation whenever models in the library change.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name	Description
VariableSource	ORC with waste heat stream with variable flow rate and temperature

Buildings.Fluid.CHPs.OrganicRankine.Validation.VariableSource

ORC with waste heat stream with variable flow rate and temperature

Buildings.Fluid.CHPs.OrganicRankine.Validation.VariableSource

Information

This model demonstrates how the ORC model reacts to variable flow rate and temperature of the incoming hot fluid carrying waste heat. Normally, the working fluid flow rate of the cycle ṁ_w is found from the set point for the evaporator pinch point temperature differential ΔT_pin,eva. This constraint is relaxed under any of the following two conditions:

If the hot fluid flow rate or temperature is too high, i.e. it carries more heat than the cycle can process, ṁ_w would exceed its upper limit. The flow rate ṁ_w is then fixed at its upper limit and ΔT_pin,eva is allowed higher than its set point.
If the hot fluid flow rate or temperature is too low, i.e. it carries to little heat, ṁ_w would be lower than a threshold. The flow rate ṁ_w is then set to zero. This effectively shuts down the cycle and the set point of ΔT_pin,eva is ignored.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
R245fa	pro		Property record of the working fluid
MassFlowRate	mHot_flow_nominal	1	Nominal mass flow rate of evaporator hot fluid [kg/s]
MassFlowRate	mCol_flow_nominal	1	Nominal mass flow rate of condenser cold fluid [kg/s]

Modelica definition

model VariableSource "ORC with waste heat stream with variable flow rate and temperature" extends Modelica.Icons.Example; package MediumHot = Buildings.Media.Air "Evaporator hot fluid"; package MediumCol = Buildings.Media.Water "Condenser cold fluid"; parameter Buildings.Fluid.CHPs.OrganicRankine.Data.WorkingFluids.R245fa pro "Property record of the working fluid"; parameter Modelica.Units.SI.MassFlowRate mHot_flow_nominal = 1 "Nominal mass flow rate of evaporator hot fluid"; parameter Modelica.Units.SI.MassFlowRate mCol_flow_nominal = 1 "Nominal mass flow rate of condenser cold fluid"; Buildings.Fluid.CHPs.OrganicRankine.ConstantEvaporation orc( redeclare package Medium1 = MediumHot, redeclare package Medium2 = MediumCol, pro=pro, tau1=0, tau2=0, energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState, T1_start(displayUnit="K") = 350, T2_start(displayUnit="K") = 290, dpHot_nominal = 0, dpCol_nominal = 0, mHot_flow_nominal=mHot_flow_nominal, mCol_flow_nominal=mCol_flow_nominal, mWor_flow_max = 3E4 / ( Buildings.Utilities.Math.Functions.smoothInterpolation( x = orc.TWorEva, xSup = pro.T, ySup = pro.hSatVap) - Buildings.Utilities.Math.Functions.smoothInterpolation( x = 300, xSup = pro.T, ySup = pro.hSatLiq)), mWor_flow_min = orc.mWor_flow_max * 0.2, TWorEva=350, etaExp=0.7, etaPum=0.7) "Organic Rankine cycle"; Buildings.Fluid.Sources.MassFlowSource_T souHot( redeclare final package Medium = MediumHot, m_flow=mHot_flow_nominal, T=orc.TWorEva + 20, nPorts=1, use_m_flow_in=true, use_T_in=true) "Evaporator hot fluid source"; Buildings.Fluid.Sources.Boundary_pT sinHot( redeclare final package Medium = MediumHot, nPorts=1) "Evaporator hot fluid sink"; Buildings.Fluid.Sources.MassFlowSource_T souCol( redeclare final package Medium = MediumCol, m_flow=mCol_flow_nominal, nPorts=1) "Condenser cold fluid source"; Buildings.Fluid.Sources.Boundary_pT sinCol( redeclare final package Medium = MediumCol, nPorts=1) "Condenser cold fluid sink"; Buildings.Fluid.Sensors.TemperatureTwoPort THotOut( redeclare final package Medium = MediumHot, final m_flow_nominal=mHot_flow_nominal, tau=0) "Outgoing temperature of evaporator hot fluid"; Buildings.Fluid.Sensors.TemperatureTwoPort TColOut( redeclare final package Medium = MediumCol, final m_flow_nominal=mCol_flow_nominal, tau=0) "Outgoing temperature of condenser cold fluid"; Modelica.Blocks.Sources.BooleanConstant tru(k=true) "Constant true"; Modelica.Blocks.Sources.TimeTable mHot_flow_set(table=[ 0,0; 20,0; 50,mHot_flow_nominal*1.5; 250,mHot_flow_nominal*1.5; 280,0; 300,0]) "Sets the hot fluid flow rate in the evaporator"; Modelica.Blocks.Sources.TimeTable THotIn_set(table=[ 0,orc.TWorEva + 20; 100,orc.TWorEva + 20; 150,orc.TWorEva - 5; 200,orc.TWorEva + 20; 300,orc.TWorEva + 20]) "Sets the hot fluid incoming temperature in the evaporator"; equation connect(souHot.ports[1],orc. port_a1); connect(souCol.ports[1],orc. port_a2); connect(sinHot.ports[1],THotOut. port_b); connect(THotOut.port_a,orc. port_b1); connect(TColOut.port_a,orc. port_b2); connect(sinCol.ports[1], TColOut.port_b); connect(tru.y, orc.ena); connect(mHot_flow_set.y, souHot.m_flow_in); connect(THotIn_set.y, souHot.T_in); end VariableSource;