Physical and Chemical Properties Division Gas Phase Kinetics Data and Databases What Information is Needed and How to Use it. Jeffrey A. Manion National

Physical and Chemical Properties Division

Gas Phase Kinetics Data and Databases Gas Phase Kinetics Data and Databases

What Information is Needed and How to Use it.What Information is Needed and How to Use it.

Jeffrey A. Manion

National Institute of Standards and TechnologyPhysical and Chemical Properties Division

Gaithersburg MD 20899

Workshop on Constructing a Kinetics Database NIST, Gaithersburg, MD

April 19, 2004


Structure of TalkStructure of Talk

PART 1: Overview of gas phase kinetic data

PART 2: Application of gas phase databases:

Combustion Chemistry: What are the data needs

NIST Real Fuels Project: Vision of how to implement change


Who Uses Databases and How?Who Uses Databases and How?

How is the data to be used?

• Archival: Storage of results for rapid retrieval

a. Numerical results; sometimes evaluationb. Adequate specification of the conditionsc. Bibliographic information

II. Use Oriented: Focus is application and extension of the data

a. All of the above, plus:b. Information to establish intrinsic relationshipsc. Information to enable additional processing

Who uses the data?

I. Experts within communityII. People from other disciplines


What is Meant by Kinetic Data?What is Meant by Kinetic Data?

Chemical Kinetics: The study of the rates of chemical reactions.

BUT: Do mechanical engineers, biochemists, and combustion chemists mean the same thing by “kinetic data” and expect the same things in a kinetics database?

Chemical Reaction: A chemical reaction is a process that results in the interconversion of chemical species.

A → B A + B → C + D

-dA/dt = k1[A] -dA/dt = k2[A]a[B]b


What do People Actually Mean? What do People Actually Mean?

From a March 2004 e-mail:

Dear Dr. Manion:I am working to improve the production of methylene chloride. The

reaction is:

CH4 + 2 HCl + 02 → CH2Cl2 + 2 H20

I was unable to find the kinetic data for the above reaction in the NIST Gas Phase Kinetics Database. Can you help me in this regard?

Not everyone distinguishes between global and elementary reactions.


Gas Phase Kinetic Data - DefinitionsGas Phase Kinetic Data - Definitions

Elementary Reaction (IUPAC): An algebraic representation of a chemical transforma-tion for which no reaction intermediates have been detected or need to be postulated to describe the chemical reaction on a molecular scale. An elementary reaction is assumed to occur in a single step and to pass through a single transition state.

CH4 + OH → [CH3 - H - OH]‡ → CH3 + H2O transferrable

Lumped Reaction: A collection of (a small number) of elementary reactions expressed as an “equivalent” apparent single-step reaction.

Global Reaction: A collection of (a large number) of elementary reactions expressed as an apparent single-step reaction.

CH4 + 2 O2 → CO2 + 2 H2O

-a -b

a bX H + X+ H

XH

transferrable underspecified conditions

Not transferrable


Kinetic Data for Gas Phase – Issues and Non-IssuesKinetic Data for Gas Phase – Issues and Non-Issues

Generally Non-Issues in Gas Phase Kinetics:

Solvent, cage effects Catalytic processes (heterogeneous) Ions and ionic processes (thermal systems – but not true for plasmas!)

In many respects, reactions in the gas phase are easiest to describe.

Complications:

I. Pressure effects (non-Boltzmann energy distributions):

Description of “Fall-off” behavior for unimolecular processes Chemical activation processes Multi-channel reactions

II. Role of theory and calculated data?

III. Real-world process modeling applications may have additional complexity (gas-surface reactions, photolytic reactions, etc.)


Part 2:Part 2:

Application of Gas Phase Kinetics DatabasesApplication of Gas Phase Kinetics Databases


Major Problems Needing Gas Phase Kinetic Data Major Problems Needing Gas Phase Kinetic Data

Process Chemistry:

Semiconductors Base

Chemicals Waste Streams

Combustion Chemistry:

Energy Production(NIST Real Fuels

Program) Waste Incineration

Scales Range from Corporate Needs to National to World Encompassing

Atmospheric Chemistry:

Troposphere Stratosphere


Common Threads: Common Threads:

Ultimate goal is the application of chemical kinetics to realistically simulate a complex system for predictive

purposes.

Databases should be designed to support the application of the data


A Closer Look at CombustionA Closer Look at Combustion


Energy Production for Transportation - National Impacts Energy Production for Transportation - National Impacts

Monetary Importance:

Economic Competitiveness Energy Self-Sufficiency Green House Gas Trading

Credits Healthcare costs

Quality of Life (Pollution Effects):

Heart/Lung Disease Environmental

Degradation Global Warming Premature death

Year 2000Number of Employees Payroll

Value of shipments

Motor Vehicle Mfg. 230,525 14.6 B 239.4 B

Transportation Equipment Mfg. 1,839,281 86.9 B 638.7 B

* “Statistics for Industry Groups and Industries: 2000”, Publication M00(AS)-1, U.S. Census Bureau, Economics and Statistics Administration, U.S. Department of Commerce, 2002.

*

Year 2000

731 Billion Liters

$272 Billion

Gasoline

Diesel

Jet

Liquid Fuels


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62.0

40.8

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10

20

30

40

50

60

70

NIST Labs Budget(Base)

Health & Environment Fuel Costs Savings

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Better Combustion: What’s the Monetary Value to the Nation?Better Combustion: What’s the Monetary Value to the Nation?

Annual Net Value of Improved Fuel Efficiency and Reduced Pollution

* “The Benefits and Costs of the Clean Air Act 1990 to 2010: EPA Report to Congress”, Table ES-1 (EPA central value converted to year 2000 dollars), EPA-410-R-99-001, U.S.EPA, 1999.

** Based on annual liquid transportation fuel cost of $272 B in the year 2000 (Energy Information Administration) and minimum estimate of 15% improved fuel efficiency increase for advanced combustion technologies such as HCCI.

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Vision: The Application of Kinetics Databases to CombustionVision: The Application of Kinetics Databases to Combustion

Physical Properties

Kinetic Data(Databases)

Refined Chemical Kinetic Model

Reduced Chemical Kinetic Model

Boundary Conditions

Experimental Observations

Chemical KineticModel

Device Simulation& Design$ $

$ +

Thermodynamic

Data (K = kf/kr)

Too Large for CFD

Computational Fluid Dynamics (CFD) Code


Current Situation with Combustion ModelingCurrent Situation with Combustion Modeling

Dilemma: How do you choose?How do you begin to compare, to improve?How much TIME will it take?

Model 1

1800 Reactions260 Species

Model 2

2200 Reactions220 Species

Reaction sets are different Rate constants are different Thermodynamic sets are different Species are identified by different strings (understandable only to creator) Data often not traceable – no reference or reference is not original source No common validation experiments

Situation: An applications engineer (non-expert kineticist) goes to the literature and is lucky to find two models of a reacting system.

Great, except:


NIST Real Fuels Project: A Vision for the Future?NIST Real Fuels Project: A Vision for the Future?


NIST Real Fuels Program - Concept NIST Real Fuels Program - Concept

NIST “Real Fuels” Program: A collaborative effort designed to enable the combustion of liquid transportation fuels (diesel, gasoline, aviation) to be realistically simulated for device design purposes.

Build Community Experimental and Kinetic

Model Development Efforts

Realistic DeviceSimulation

Real Fuels

Complex Mixtures

(100’s compounds

but few classes)

Surrogate Fuels

Small # compounds

representing chemical

classes

Match Physical &Chemical Properties

Workshop on Combustion Simulation Databases for Real Transportation Fuels, National Institute of Standards and Technology, Gaithersburg, MD, September 4-5, 2003.


Components of NIST Real Fuels ProjectComponents of NIST Real Fuels Project

Experimental:

Surrogate fuels concept Experiments to fill knowledge gaps

Infrastructural:

Design intelligent data structures for combustion information Create web-accessible data warehouse for combustion

modeling Promote collaborative paradigm for development of chemical kinetic models of combustion systems

Won’t solve all problems, but can:

take key steps lay the foundation for systematic progress


Partnering: NIST – PrIMe – CMCS CollaborationPartnering: NIST – PrIMe – CMCS Collaboration

Collaboratory for Multi-scale Chemical Science (CMCS): DOE funded computer science project whose goal is to to enhance chemical science research by developing an adaptive informatics infrastructure. Larry Rahn, Sandia - CMCS.org

Process Informatics Model effort (PrIMe): A community effort to develop predictive reaction models for combustion. The goal is to convert model building into a science, automate the methodology, and provide the results to the User in a prompt and convenient format. (Outgrowth of GRI-Mech) Michael Frenklach - UCB


NIST – PrIMe – CMCS CollaborationNIST – PrIMe – CMCS Collaboration

NIST PrIMe Data Warehouse:

All kinetic data on elementary

reactions relevant to combustion(NIST Gas Kinetics, GRI Mech)

Relevant thermodynamic data Inclusion of global kinetic data for

model validation?

PrIMe Process (Vision):

Community-based evaluation of Warehouse

Data “Best” values Selected set of “Best” validation experiments

for combustion models Set of Community Tools for “on-the fly”

generation of “Best Current Kinetic Model”

CMCS: Implementation of Computer Science Infrastructure.

Kinetic Data(Databases)

Refined Chemical Kinetic Model

Experimental Observations

Chemical KineticModel

Thermodynamic

Data (K = kf/kr) Reduced Chemical Kinetic Model

Tools

Tools

Tools

Tools


Take Home Message Take Home Message

Databases should be designed to support the use of the data.

Rapid access to gas phase kinetic information is nice –

but terribly insufficient.

Value of gas phase kinetic information is in the aggregate content.

Value is greatly diminished in the absence of infrastructure to efficiently process and share large amounts of data.

Need is ability to (rapidly) validate and apply traceable information to problems and then analyze and refine the results.


Designing Data Structures to Enable AutomationDesigning Data Structures to Enable Automation

AutomatedMolecule

Classification

Mol File

atom/connectivity

information

Choice 1: A CAS number or some other “meaningless” string

Unique identifier, but establishes no relationships between data

Example: How does one identify a molecule in the database?

Better:

Choice 2: Include a structural representation relatable to chemical information

e.g. mol file or similar

Enables SARs for Molecules & Rxns “Expert Systems” Development for:

See Posters by Don Burgess & Dave Matheu

•Data estimation•Data evaluation•Automated uncertainty estimates•Automated mech. generation


Final Comments and a Question Final Comments and a Question

Gas Phase Chemical Kinetic Data is incredibly important to solving a variety of National Problems

Intelligently designed databases and appropriate cyberinfrastructure and knowledge management tools are incredibly important.

Scientists need to develop new paradigms for working together.

Funding agencies need to recognize and support these efforts.

Is Gas Phase Database Model Applicable to Other Types of Kinetic Data?

Documents

Physical and Chemical Properties Division Gas Phase Kinetics Data and Databases What Information is Needed and How to Use it. Jeffrey A. Manion National