Università degli Studi di Roma Tor Vergata Modeling Combustion of Methane- Hydrogen Blends in Internal Combustion Engines (BONG-HY)

Università degli Studi di Roma Tor Vergata Modeling Combustion of Methane- Hydrogen Blends in Internal Combustion Engines (BONG-HY) Prof. Stefano Cordiner Ing. Vincenzo Mulone Ing. Riccardo Scarcelli

Index Target of the Work Computational Tools Turbulent Combustion Models Approach and Results Conclusions and Future Perspectives

Target Numerical Study of the Influence of Substitution of Methane with Hydrogen (15% vol.) on Combustion 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 1 2 3 4 Volumetric Efficiency Calculation

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 ( ) i i i i i Y u x m J x x Y u t Y + = + α α α α α α ρ ρ ρ &, ~ ~ ~ Turbulent Combustion Models Combustion Model ( ) T u x c q h m t p J x x T u t T c p r n i i i T p + = + = α α α α α α ρ ρ ρ 0, ~ ~ ~ & Turbulence Model (k-ε) Thermo-Fluid-Dynamics Equations System. Unknown Terms Closure

Combustion Model: CFM (Flamelet) Main Hypothesis two zones (burned-unburned) laminar local properties (s L ) Corrugated Flame Front Burned Domain Unburned Domain CFM constants m& ( ρσ) t fuel = u L 0 f 0 + RΣ = ( ρ s I Y )Σ ( ρuσ) ρd Σ ρσ ρ s L flame laminar speed Σ flame surface for volume unit = αγ k Reaction rate ( ρσ) k βρrsl ( ρσ) 2 ε ρ Y1 Transport equation 2 ( u) ρσ 10

Index Target of the Works Computational Tools Turbulent Combustion Models Approach and Results Conclusions and Future Perspectives

Approach EXPERIMENTAL SETUP MODEL CALIBRATION AND VALIDATION RELIABLE COMPUTATIONAL TOOL PARAMETERS OPTIMIZATION EXPERIMENTAL TESTS NO TARGET YES

Approach First Interaction with Experiments Interpretation of Experimental Pressure Data Modifications and Model Validation Second Interaction with Experiments Parametric Study to Optimize the Engine CPU Re-Mapping and Experimental Tests

Experimental Pressure Analysis AVL instrumentation Pressure Transducer in Combustion Chamber (sp) Charge Amplifier (amp) Optical Shaft Encoder (se) 14

Experimental Pressure Analysis AVL instrumentation Pressure Cycle IMEP Torque 15

Interpretation of Experimental Data Analysis of Experimental Pressure Data from ENEA 1D Simulation to Calculate Cylinder Volumetric Efficiency (λ v ) 3D Simulation to Calibrate CFM Model Constants on the Engine (Methane Case)

Model Calibration (Methane Case)

Combustion of Methane and Hydrogen Blends Flame Speed Calculation (Cantera) m& fuel = u L 0 f 0 RΣ = ( ρ s I Y )Σ s L = f ( ) p T, φ, x, H 2 GRI-MECH 3.0 Mechanism 53 Chemical Species 325 Reactions

Model Validation (CH 4 -H 2 Blends Case)

Approach Results First Interaction with Experiments Interpretation of Experimental Pressure Data Implementation and Model Validation Second Interaction with Experiments Parametric Study to Optimize the Engine CPU Re-Mapping and Experimental Tests Pressure Cycle Performance Chamber Temperature [NO X ]

Spark Advance Optimization for Stoichiometric Blends Higher Flame Speed for Methane-Hydrogen Blends Higher Performance

Spark Advance Optimization for Stoichiometric Blends Higher Flame Speed for Methane-Hydrogen Blends Slight ignition time delay to minimize NO X, while maintaining performance 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

Lean Burn Combustion. Performance 10 9.5 9 8.5 8 7.5 7 CH4 MIX lambda 1.0 MIX lambda 1.1 MIX lambda 1.2 MIX lambda 1.3 MIX lambda 1.4 6.5 6 pmi [310:480]

Lean Burn Combustion. Chamber Temperature CA 380 λ = 1.0 λ = 1.4

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 (CO 2, HC). The increase in [NO X ] 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 (λ v )

Spark Advance Optimization for Lean Mixtures Increase Spark Time Advance Increase Pressure and Temperature Increase [NO X ]