recordCHPEngDataBaseRecord

Base record for CHP engine data

Extends from Modelica.Icons.Record (Icon for records).

Information

Overview

Data base record for CHP power units. The nominal / rated operation point most likely corresponds to the given full load performance.

Requirements

These quantities must be known for reliable simulation (by value, variable relation etc.):

- Heat and Power: Q_MaxHea, etaCHP(Hi)

- Engine Geometry: hStr, dCyl, z, i

- Generator specification: p or n0, n_nominal, U_1, P_elNominal, f_1

- Lambda or xO2Exh: Required for calculation of the engine combustion, heat flow and the exhaust gas composition (Lambda = 0.21 / (0.21 - xO2Exh))

- nEngNominal

- dInn (typical values around 0.005m, important for heat transfer from engine to cooling)

Default values and variable relations

These are the default values or relations in case that there is no information available:

- nEngMax: Engine speed at full load (=nEngNominal)

- etaGen: Generator efficiency (default=0.92)

- I_elNominal (=P_elNominal/(sqrt(3)*U_1*cosPhi))

- P_mecNominal (=P_elNominal/etaGen)

- P_FueNominal (=(P_elNominal+Q_MaxHea)/etaCHP)

- VEng (default=0.25*hStr*Modelica.Constants.pi*dCyl^2*z)

- mEng (default=70389*VEng+17.913, for first appraisal of the heat capacities of engine housing, should be calibrated)

- eps (typical values around 12 (SI) and 21 (DI))

- T_ExhPowOut (default=373.15K)

- gearRatio (default=1)

- cosPhi (default=0.8)

- useGenHeat (default=false)

- Exhaust and Coolant: dExh(default=0.06m), dCoo(default=0.04m), dp_Coo(default=0.15bar), m_flowCooNominal(default=0.00003*Q_MaxHea-0.2043)

- Engine material: lambda, rhoEngWall, c (default is cast iron(most common))

Parameters

TypeNameDefaultDescription
BooleanSIEnginetrueDefault:True=SI-Engine(Otto) / False=DI-Engine(Diesel)
StringEngMat"CastIron"Name of the engine material(Choices: CastIron, SpheroidalGraphiteIron, CastAluminium)
RotationSpeednEngMaxnEngNominalEngine speed at full load (default=nEngNominal)
RotationSpeednEngNominalNominal engine speed at nominal operating point
RealQuoDCyldCyl/ref_dCylComparison of cylinder diameter to the reference
RealxO2Exh0.05Residual oxygen content in the exhaust gas(default value is 5%)
RealLambda0.21/(0.21 - xO2Exh)Engine air ratio (default value is 1.31; min=1.01)
RealzNumber of cylinders
Realepsif SIEngine then 12 else 21Compression ratio (default values are 12(SI) and 21(DI))
RealiNumber of combustion for one operating cycle (1->two-stroke, 0.5->four-stroke)
Modelica.Units.SI.MassmEng70389*VEng + 17.913Total dry weight of the engine block
Modelica.Units.SI.VolumeVEng0.25*hStr*Modelica.Constants.pi*dCyl^2*zEngine displacement
Modelica.Units.SI.LengthhStrStroke
Modelica.Units.SI.LengthdCylCylinder diameter
Modelica.Units.SI.Lengthref_dCyl0.091Reference cylinder diameter for friction calculation
Modelica.Units.SI.Pressureref_p_mfNominalif SIEngine then 75000 else 110000Friction mean pressure of reference engine for calculation(dCyl=91mm & nEng=3000rpm & TEng=90°C)
Modelica.Units.SI.Pressurep_meNominalP_mecNominal/(i*nEngNominal*VEng)Nominal mean effective cylinder pressure
Modelica.Units.SI.EfficiencyetaCHPNominal efficiency of the power unit referring to the fuel input
Modelica.Units.SI.EfficiencyetaGen0.92Generator efficiency
Modelica.Units.SI.PowerP_mecNominalP_elNominal/etaGenMechanical power output of the engine at nominal operating point
Modelica.Units.SI.PowerP_FueNominal(P_elNominal + Q_MaxHea)/etaCHPNominal fuel expenses
Modelica.Units.SI.PowerQ_MaxHeaMaximum of usable heat
Modelica.Units.SI.TemperatureT_ExhPowUniOut373.15Exhaust gas temperature after exhaust heat exchanger (default=100°C)
Modelica.Units.SI.DiameterdExh0.0612 + (Lambda*P_FueNominal)*10^(-7)Exhaust pipe diameter for heat transfer calculation
Modelica.Units.SI.DiameterdCoo0.0224 + Q_MaxHea*2*10^(-7)Coolant circle pipe diameter for heat transfer calculation
Modelica.Units.SI.ThicknessdInnThickness of the cylinder wall between combustion chamber and cooling circle (default value is 5mm)
Modelica.Units.SI.MassFlowRatem_floCooNominal0.00003*Q_MaxHea - 0.2043Nominal mass flow rate of coolant inside the engine cooling circle (default density of coolant is 1kg/l)
Modelica.Units.SI.Pressuredp_Coo15000Pressure loss between coolant supply and return flow (default value is 0.15bar)
RealcosPhi0.8Power factor of electric machine (default=0.8)
Realpf_1/n0Number of pole pairs
RealgearRatio1Gear ratio: engine speed to generator speed (default=1)
BooleanuseHeatfalseIs the thermal loss energy of the elctric machine used?
Modelica.Units.SI.Frequencyn0f_1/pIdling speed of the electric machine
Modelica.Units.SI.Frequencyn_nominalRated rotor speed [1/s]
Modelica.Units.SI.Frequencyf_1Source frequency
Modelica.Units.SI.VoltageU_1Rated voltage
Modelica.Units.SI.CurrentI_elNominalP_elNominal/(sqrt(3)*U_1*cosPhi)Rated current
Modelica.Units.SI.PowerP_elNominalNominal electrical power of electric machine

Contents

NameDescription
RotationSpeed
AirRatio