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

( )iiiii Yu

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xxY

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∂∂

−+∂∂

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αα

ααα

α ρρρ &,

~~

~

Turbulent Combustion Models

Combustion Model

( )Tux

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xxTu

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=α

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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∇⋅∇−Σ⋅∇+

∂Σ∂

Σ ρρ

ρβρρε

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YskDu

tLR

k1

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2

)(

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”