Hypersonic fuels chemistry n heptane cracking and combustion
This presentation is the property of its rightful owner.
Sponsored Links
1 / 25

Hypersonic Fuels Chemistry: n-Heptane Cracking and Combustion PowerPoint PPT Presentation


  • 75 Views
  • Uploaded on
  • Presentation posted in: General

Hypersonic Fuels Chemistry: n-Heptane Cracking and Combustion. Andrew Mandelbaum - Dept. of Mechanical Engineering, Princeton University Alex Fridlyand - Dept. of Mechanical Engineering, University of Illinois at Chicago

Download Presentation

Hypersonic Fuels Chemistry: n-Heptane Cracking and Combustion

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Hypersonic fuels chemistry n heptane cracking and combustion

Hypersonic Fuels Chemistry:n-Heptane Cracking and Combustion

Andrew Mandelbaum - Dept. of Mechanical Engineering, Princeton University

Alex Fridlyand - Dept. of Mechanical Engineering, University of Illinois at Chicago

Prof. Kenneth Brezinsky - Dept. of Mechanical Engineering, University of Illinois at Chicago


Outline

Outline

  • Project Background

  • Hypothesis

  • Experimental Apparatus and Methods

  • Results and Modeling

    • Heptane Pyrolysis

    • Heptane Oxidation

    • Heptane/Ethylene Oxidation

  • Conclusions


Project background

Project Background

  • Heat management

  • Very short reaction time requirements

Fig. 1: Cross-sectional diagram of a scramjet engine1

1. How Scramjets Work [online]. NASA. 2 Sept. 2006. 4 June 2011. http://www.nasa.gov/centers/langley/news/factsheets/X43A_2006_5.html.


Project background1

Project Background

  • Use fuel to cool engine structure

  • Shorter cracking products may ignite more readily

Fig. 2: Ignition delay vs. temperature for various pure gases and mixtures2

2. M. Colket, III and L. Spadaccini: Journal of Propulsion and Power, 2001, 17.2, 319.


Consequence questions raised applications

Consequence, Questions Raised, Applications

  • Injected fuel – different from fuel in tank

  • Effect on combustion products?

  • What causes the change in energy output – physical or chemical differences?

  • Improved chemical simulations

    • Improved accuracy

    • Use in engine modeling software

    • Possibility for fuel composition customization


Hypothesis

Hypothesis

  • Heptane cracking products (primarily ethylene) will chemically influence combustion of remaining fuel

  • Resultant species - differ in from non-cracked fuel alone and from existing heptane models


Low pressure shock tube

Low Pressure Shock Tube

  • Designed to operate from 0.1-10 bar, 800-3000 K, 1-3 ms reaction time

  • Explore oxidation chemistry at pressures relevant to hypersonic engine combustor

Fig. 3: Schematic drawing of low pressure shock tube and related assemblies


Methods

Methods

  • Perform pyrolysis and oxidation shocks at 4 bar driver pressure

  • Examine stable intermediates and fuel decay process using gas chromatography (GC-FID/TCD)

  • Model used: n-Heptane Mechanism v3, Westbrook et al3, 4, 5

  • Note: all graphs have x-error of ±5-10 K (from pressure transducers) and y-error of ±5-10% (from standards used in calibrations and GC error). Error bars are omitted for clarity

  • 3. Mehl, M., H.J. Curran, W.J. Pitz and C.K. Westbrook: "Chemical kinetic modeling of component mixtures relevant to gasoline," European Combustion Meeting, 2009. 

  • 4. Mehl, M., W.J. Pitz, M. Sjöberg and J.E. Dec: “Detailed kinetic modeling of low-temperature heat release for PRF fuels in an HCCI engine,” S AE 2009 International Powertrains, Fuels and Lubricants Meeting, SAE Paper No. 2009-01-1806, Florence, Italy, 2009. 

  • 5. Curran, H. J., P. Gaffuri, W. J. Pitz, and C. K. Westbrook: Combustion and Flame,1998, 114, 149-177


Heptane pyrolysis

Heptane Pyrolysis

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

  • Pyrolyze to characterize decomposition and species formed

Fig. 4: Concentration of heptane vs. T5 during pyrolysis


Heptane pyrolysis continued

Heptane Pyrolysis (Continued)

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

  • Ethylene is the primary product by concentration

Fig. 5: Concentration of ethylene vs. T5 during pyrolysis


Heptane pyrolysis continued1

Heptane Pyrolysis (Continued)

  • Possible directions for future research

Fig. 6: Concentration of acetylene, methane, and propylene vs. T5 during pyrolysis


Heptane pyrolysis modeling

Heptane Pyrolysis - Modeling

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

  • Model results to validate shock tube operation

Fig. 7: Comparison of pyrolysis data to model results for heptane decomposition


Heptane oxidation modeling and data

Heptane Oxidation – Modeling and Data

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

Φ=1.38

Fig. 8: Comparison of oxidation data to model results for oxygen concentration


Heptane oxidation modeling and data cont d

Heptane Oxidation – Modeling and Data (Cont’d)

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

Φ=1.38

Fig. 9: Comparison of oxidation data to model results for ethylene concentration


Heptane oxidation modeling and data cont d1

Heptane Oxidation – Modeling and Data (Cont’d)

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

Φ=1.38

Fig. 10: Comparison of oxidation data to model results for carbon monoxide production


Heptane with ethylene oxidation

Heptane with Ethylene Oxidation

Fig. 11: Normalized heptane concentration and ethylene concentration vs. T5 for neat mixture and cracked fuel mixture


Heptane with ethylene oxidation1

Heptane with Ethylene Oxidation

Pdriver=4 bar

Rxn time: 1.5-1.8 ms

Φ=1.38

Figure 12: Carbon monoxide concentration vs. T5 for pure heptane oxidation and heptane with ethylene


Conclusions and future work

Conclusions and Future Work

  • Heptane cracking products affect combustion of non-cracked fuel through chemical processes

  • CO, CO2, and H2O production - energy output differences

  • Future experiments - other cracking products and/or different reaction pressures


Acknowledgements

Acknowledgements

  • National Science Foundation, EEC-NSF Grant # 1062943

  • University of Illinois at ChicagoREU

  • Prof. Christos Takoudis and Dr. Gregory Jursich

  • Arman Butt and Runshen Xu


Questions

Questions

6

6. http://www.af.mil/shared/media/photodb/photos/100520-F-9999B-111.jpg


Calibrations

Calibrations

  • Temperature calibrations using TFE and CPCN

  • Known decomposition rates allow these species to be used as chemical thermometers

Fig. 13: TFE and CPCN shock calibration results


Heptane with ethylene oxidation cont d

Heptane with Ethylene Oxidation (Cont’d)

Fig. 14: Butene concentration vs. T5 for neat mixture and cracked fuel mixture


Heptane with ethylene oxidation cont d1

Heptane with Ethylene Oxidation (Cont’d)

Fig. 15: Oxygen concentration vs. T5 for neat mixture and cracked fuel mixture


Heptane w ethylene modeling

Heptane w/ Ethylene - Modeling

  • Model cracked fuel mix with and without complete hydrogen balance to validate mixture

Fig. 16: Carbon monoxide concentration vs. T5 for neat mixture and mixtures with and without hydrogen balance


Heptane w ethylene modeling cont d

Heptane w/ Ethylene – Modeling (Cont’d)

  • Decreased H2O output without H balance

Fig. 17: Water concentration vs. T5 for neat mixture and mixtures with and without hydrogen balance


  • Login