Post on 01-Aug-2020
Modeling Combustion of MethaneModeling Combustion of Methane--
Hydrogen Blends in Internal Hydrogen Blends in Internal Combustion EnginesCombustion Engines
(BONG(BONG--HY)HY)
Prof.
Stefano Cordiner
Ing.
Vincenzo Mulone
Ing.
Riccardo Scarcelli
Università
degli Studi di Roma “Tor Vergata”
Index
Target of the Work
Computational Tools
Turbulent Combustion Models
Approach and Results
Conclusions and Future Perspectives
Index
Target of the Work
Computational Tools
Turbulent Combustion Models
Approach and Results
Conclusions and Future Perspectives
Numerical Study of the Influence of Substitution of Methane with Hydrogen (15% vol.) on Combustion
Target
Numerical Analysis of the Influence of Main Engines Parameters (Spark Advance and Air Index) on Performance and Emissions
NUMERICAL-EXPERIMENTAL PROCEDURE FOR ENGINE OPTIMISATION
Index
Target
Computational Tools
Turbulent Combustion Models
Approach and Results
Conclusions and Future Perspectives
1D Codes: Framework Code (FW2000)
Analysis of the Behaviour
of the whole Engine
Integrated Code 0D-1D• Zero-dimensional elements
(capacities, cylinder-piston)
• One-dimensional elements (ducts, heat exchangers)
• Joint elements
Volumetric Efficiency Calculation
2 3 41
3D Codes: KIVA-3V Code
Analysis of Cylinder -
Piston System
• Open Source CFD code
• Models of injection, ignition, turbulent combustion
• A. L. E. Algorithm
• Moving Structured Grids (Piston –
Valves Simulation)
Local Description of Combustion Process
Index
Target
Computational Tools
Turbulent Combustion Models
Approach and Results
Conclusions and Future Perspectives
9
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~~
~
Turbulent Combustion Models
Combustion Model
( )Tux
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Turbulence
Model (k-ε)
Thermo-Fluid-Dynamics Equations System.Unknown Terms Closure
10
Combustion Model: CFM (Flamelet)
( ) ( ) ( ) ( ) Σ⋅∇−Σ
−ΣΓ=⎟⎟⎠
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∂Σ∂
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YskDu
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)(
Transport equation
Σ
flame surface for volume unit
Unburned DomainUnburned Domain
Corrugated Corrugated Flame FrontFlame Front
Burned DomainBurned Domain
CFM constants
Main Hypothesis• two zones (burned-unburned)• laminar local properties (sL
)
sL
flame laminar speed
Reaction rate( )Σ=Σ= 00 fLufuel YIsRm ρ&
Index
Target of the Works
Computational Tools
Turbulent Combustion Models
Approach and Results
Conclusions and Future Perspectives
Approach
EXPERIMENTALSETUP
RELIABLECOMPUTATIONAL
TOOL
MODEL CALIBRATION AND VALIDATION
PARAMETERS OPTIMIZATION
TARGET
YES
NO
EXPERIMENTALTESTS
Approach
First Interaction with ExperimentsInterpretation of Experimental Pressure Data
Modifications and Model Validation
Second Interaction with ExperimentsParametric Study to Optimize the Engine
CPU Re-Mapping and Experimental Tests
14
Pressure Transducer in Combustion Chamber (sp)Charge Amplifier (amp)Optical Shaft Encoder (se)
Experimental Pressure AnalysisAVL instrumentation
15
Experimental Pressure Analysis
Pressure Cycle IMEP Torque
AVL instrumentation
Interpretation of Experimental Data
Analysis of Experimental Pressure Data from ENEA
1D Simulation to Calculate Cylinder Volumetric Efficiency (λv)
3D Simulation to Calibrate CFM Model Constants on the Engine (Methane Case)
Model Calibration (Methane Case)
( )2
,,, HL xTpfs φ=
Combustion of Methane and Hydrogen Blends
Flame Speed Calculation (Cantera)
( )Σ=Σ= 00 fLufuel YIsRm ρ&
GRI-MECH 3.0 Mechanism
53 Chemical Species
325 Reactions
Model Validation (CH4
-H2
Blends Case)
Approach Results
Pressure Cycle Performance
Chamber Temperature [NOX ]
First Interaction with ExperimentsInterpretation of Experimental Pressure Data
Implementation and Model Validation
Second Interaction with ExperimentsParametric Study to Optimize the Engine
CPU Re-Mapping and Experimental Tests
Spark Advance Optimization for Stoichiometric Blends
Higher Flame Speed for Methane-Hydrogen Blends
Higher Performance
Spark Advance Optimization for Stoichiometric Blends
OPERATING CONDITIONS IGNITION TIME DELAY
1500 RPM 25% LOAD +2
1500 RPM 50% LOAD +4
2500 RPM 25% LOAD +2
2500 RPM 50% LOAD +4
3500 RPM 25% LOAD +3
3500 RPM 50% LOAD +4
Higher Flame Speed for Methane-Hydrogen Blends
Slight ignition time delay to minimize NOX , while
maintaining performance
Lean Burn Combustion. Performance
6
6.5
7
7.5
8
8.5
9
9.5
10
pmi [310:480]
CH4MIX lambda 1.0MIX lambda 1.1MIX lambda 1.2MIX lambda 1.3MIX lambda 1.4
Lean Burn Combustion. Chamber Temperature
λ = 1.0
λ = 1.4
CA 380°
Index
Target of the Work
Computational Tools
Turbulent Combustion Models
Approach and Results
Conclusions and Future Perspectives
Conclusions
The Introduction of Hydrogen into a Methane/Air Mixture provides Increased Flame Propagation Speed, thus leading to Higher Performance and Reduced Emissions (CO2, HC). The increase in [NOX] can be contained by following two approaches:
A decrease in spark time advance (+4° for all operating conditions) for stoichiometric mixtures. Results are a decrease in CO2 emissions (-15%) and a slight reduction in performance (-10%)
The utilization of lean mixtures (λ>1.4) with unchanged spark advance, with a further reduction of CO2 emissions (-20%), even though performance drastically drop (-50%)
Future Perspectives
Spark Advance Optimization for Lean Mixtures.Study of Flammability Limits of Methane-Hydrogen Blends
Development of NOx formation models
Design of combustion chambers and ducts to improve volumetric efficiency (λv)
Spark Advance Optimization for Lean Mixtures
Increase Spark Time Advance
Increase Pressure and Temperature
Increase [NOX ]
Modeling Combustion of MethaneModeling Combustion of Methane--
Hydrogen Blends in Internal Hydrogen Blends in Internal Combustion EnginesCombustion Engines
(BONG(BONG--HY)HY)
Prof.
Stefano Cordiner
Ing.
Vincenzo Mulone
Ing.
Riccardo Scarcelli
Università
degli Studi di Roma “Tor Vergata”