simulation of the tail-pipe emissions for a heavy duty diesel
TRANSCRIPT
Simulation of the Tail-Pipe Emissions fora Heavy Duty Diesel Engine in GT -Power
GT-Suite Users MeetingOct. 20, 2012, Frankfurt/Main
Dr. Joachim WeißDipl.-Ing. Markus Raup
Dr. Thorolf Schatzberger
Dipl.-Ing. Friedrich ForsthuberDipl.-Ing. Thorsten Krenek
Assistant Prof. Dr. Thomas Lauer
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 2
Content
� Introduction
� Simulation model
� Validation Results
� Variation of exhaust system
� Optimization – mean value model
� Summary & outlook
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 3
IntroductionMotivation
� State-of-the-art engines are complex systems with numerous degrees of freedom
� Fuel efficiency is strong demand from the customer
� Emission regulations getting continuously more severe
� Comprehensive model required to study system behavior
� Simulation model as basis for numerical optimization
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 4
IntroductionEngine & Simulation Software
Heavy duty engine for truck and bus application:
� In-line 6-cylinder Diesel engine
� High-pressure common rail injection system with multiple injection pulses
� Two-stage turbo charging with intercooler
� Cooled external EGR
� Selective catalytic reduction (SCR)
� Diesel particulate filter (DPF)
� Diesel oxidation catalyst (DOC)
Simulation Software
� GT-Suite™ for simulation of engine and aftertreatment
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012| Frankfurt/Main | F. Forsthuber | Slide 5
Simulation ModelCombustion Modeling – Spray Model
Source: Hiroyasu et al., SAE-Paper 930612
Spray model• Input: injection rate vs. time
• Spray divided in parcels
• Evaporation and heat release for individual parcel is computed
• Global heat release is summed up
• NOx model based on extended Zeldovich mechanism
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 6
Simulation ModelCombustion Modeling – Resulting Cylinder Pressure
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 7
Simulation ModelAftertreatment Modeling
Flow components (catalyst bricks)
Coupled with reaction kinetics objects
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 8
Simulation ModelAftertreatment Modeling – Reaction Kinetics
Reaction kinetics objects account for:
� Bulk diffusion
� Surface storage
� Gas and surface reactions
Adsorption of ammonia
Desorption of ammonia
Oxidation of ammonia
Standard SCR reaction
Slow SCR reaction
Fast SCR reaction
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 9
Simulation ModelOverall System Modeling
Predictive engine model for fuel consumption and NOx formation
Aftertreatment model with detailed reaction kinetics
Combination of the two parts
required
� One single model with two separated flow circuits
� Boundary conditions of circuits passed through by a control object
� Appropriate timestep for each circuit to provide fast runtimes
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 10
Validation ResultsSteady-State Engine Operating Points – 50% Load
� Comparison between measurements and simulation results of different operating points
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 11
Validation ResultsSteady-State Engine Operating Points – Parameter Variation
Variation of air ratio (Lambda) in one specific operating point
Engine control strategy: Increasing Lambda � decreasing EGR
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 12
Validation ResultsAftertreatment
� Steady-state operating point� Constant exhaust mass flow, composition and temperature� Injection of urea solution (hyperstoichiometric)� NOx conversion and NH3 storage starts� Cut-off of urea injection
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 13
Validation ResultsAftertreatment
� WHTC based transient cycle
� Last section of cycle – urea dosing and NOx conversion start
� Measured raw emissions as input for afterteratment model
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 14
Validation ResultsTransient Cycle
� Combined model with detailed engine and aftertreatment model
� Transient cycle based on the Worldwide Harmonized Transient Cycle (WHTC)
� Fully transient controls for engine and atftertreatment operation analogous to the hardware engine control
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 15
Validation ResultsTransient Cycle – Parameter Variation
� Variation of air ratio (lambda factor) over the entire transient cycle
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012| Frankfurt/Main | F. Forsthuber | Slide 16
Validation ResultsTransient Cycle – Parameter Variation
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012| Frankfurt/Main | F. Forsthuber | Slide 17
Variations of Exhaust System
Base Reduced lengthAir-gap
insulation 1Air-gap
insulation 2
be 100% +0,2% -0,1% +0,1%
NOx 100% -0,3% -0,3% -0,7%
NOx,EOP 100% -14% -13% -19%
tAdBlue 100% -5,1% -4,9% -6,2%
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 18
Optimization – Mean Value Model• One neural network for
each output parameter:• IMEP• FMEP• Volumetric Efficiency• Exhaust temperature• NO emissions• NO2 emissions
• 15,000 steady-statesimulations for neuralnetwork training
Runtime reduction:15 hrs → 45 min for a 1800 s transient cycle
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012| Frankfurt/Main | F. Forsthuber | Slide 19
Optimization – Mean Value Model
� Design of Experiments
� Full factorial
� 720 simulated transient cycles
� Neural network as objective function
� Minimization of BSFC
� Boundary condition:
NOx,EOP ≤ base variant
� Optimized Parameters:− Lambda Multiplier
− Charge pressure multiplier
− Site density
− SCR catalyst length
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012 | Frankfurt/Main | F. Forsthuber | Slide 20
Optimization – Mean Value Model
Final OptimizationResults
BSFC -2.1%
NOx -4,9%
NOx,EOP -4.0%
Optimized parameter set combined with insulated exhaust pipes
Optimization result verified with detailed model
GT-Suite Users MeetingSimulation of the Tail-Pipe Emissions for a Heavy Duty Diesel Engine in GT-Power
Oct. 22, 2012| Frankfurt/Main | F. Forsthuber | Slide 21
Summary & Outlook
� Summary− Predictive simulation model containing engine and aftertreatment
− Phenomenological Diesel combustion model for fuel consumption and NOx formation
− Aftertreatment with reaction kinetics (NH3 storage and NOx conversion)
− Sensitive to the relevant parameters of engine and aftertreatment operation
− Steady state operating points and transient cycles
− Neural network model for faster runtimes
− Numerical optimization methods
� Outlook− Extended reaction kinetics
− Advanced numerical optimization methods (heuristic algorithms…)
Thank you for your attention !
Dipl.-Ing. Friedrich [email protected]