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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

Investigation of Physical and Chemical Delay Periods of Different Fuels in the Ignition Quality Tester

[+] Author and Article Information
Ziliang Zheng

Graduate Research Assistant
e-mail: zhengziliang@gmail.com

Tamer Badawy

Research Assistant
e-mail: Eng.tam@gmail.com

Naeim Henein

Professor
e-mail: henein@eng.wayne.edu
Wayne State University,
Detroit, MI 48202

Eric Sattler

US Army RDECOM-TARDEC,
Warren, MI 48092
e-mail: eric.r.sattler.civ@mail.mil

Contributed by the Combustion and Fuels Committee of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received August 20, 2012; final manuscript received January 31, 2013; published online May 20, 2013. Assoc. Editor: Joseph Zelina.

J. Eng. Gas Turbines Power 135(6), 061501 (May 20, 2013) (11 pages) Paper No: GTP-12-1335; doi: 10.1115/1.4023607 History: Received August 20, 2012; Revised January 31, 2013

This paper investigates the physical and chemical ignition delay (ID) periods in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT was used to determine the derived cetane number (DCN) according to ASTM D6890-10a standards. The fuels tested were ultra low sulfur diesel (ULSD), jet propellant-8 (JP-8), and two synthetic fuels of Sasol IPK and F-T SPK (S-8). A comparison was made between the DCN and cetane number (CN) determined according to ASTM-D613 standards. Tests were conducted under steady state conditions at a constant pressure of 21 bars and various air temperatures ranging from 778 K to 848 K. The rate of heat release (RHR) was calculated from the measured pressure trace, and a detailed analysis of the RHR trace was made particularly for the auto-ignition process. Tests were conducted to determine the physical and chemical delay periods by comparing results obtained from two tests. In the first test, the fuel was injected into air according to ASTM standards. In the second test, the fuel was injected into nitrogen. The point at which the two resultant pressure traces separated was considered to be the end of the physical delay period. The effects of the charge temperature on the total ID as defined in ASTM D6890-10a standards, as well as on the physical and chemical delays, were determined. It was noticed that the physical delay represented a significant part of the total ID over all the air temperatures covered in this investigation. Arrhenius plots were developed to determine the apparent activation energy for each fuel using different IDs. The first was based on the total ID measured according to ASTM standards. The second was the chemical delay determined in this investigation. The activation energy calculated from the total ID showed higher values for lower CN fuels except Sasol IPK. The activation energy calculated from the chemical delay period showed consistency in the increase of the activation energy with the drop in CN including Sasol IPK. The difference between the two findings could be explained by examining the sensitivity of the physical delay period of different fuels to the change in air temperature.

Copyright © 2013 by ASME
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References

Figures

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Fig. 1

A sample of traces for the needlelift and chamber pressure depicting the definition of IQT ignition delay time

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Fig. 2

Schematic of the Ignition Quality Tester setup at Wayne State University

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Fig. 3

ASTM D613 CN and D6890 DCN versus ID period for different fuels

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Fig. 4

Raw data of N.L, pressure, and RHR traces for n-heptane

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Fig. 5

(a) Filtered pressure and needlelift signals for four fuels. (b) Spectral analysis for the filtered signals of pressure and needlelift for different fuels.

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Fig. 6

Traces for needlelift, pressure, RHR, and temperature for injection of heptane in air and in nitrogen

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Fig. 7

Pressure, needlelift, RHR, and temperature traces for four fuels tested at temperature 828 K

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Fig. 8

Details of RHR traces during auto-ignition for four fuels at temperature 828 K

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Fig. 9

Normalized integral RHR of four fuels at temperature 828 K

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Fig. 10

(a) Physical ID versus integrated mean temperature during the physical process. (b) Chemical ID versus integrated mean temperature during the chemical process.

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Fig. 11

Chamber pressure and temperatures before SOI and mean pressure versus integrated mean temperature during the ID period

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Fig. 12

3D plot of the ID period, integrated mean temperature, and DCN

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Fig. 13

(a) Arrhenius plots for total ignition delay versus the charge temperature before SOI for different fuels. (b) Arrhenius plots for total ignition delay versus the integrated mean temperature during ID period for different fuels.

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Fig. 14

Arrhenius plots for chemical ignition delay versus the integrated mean temperature for different fuels

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Fig. 15

Arrhenius plots for physical ignition delay versus the integrated mean temperature for different fuels

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Fig. 17

(a) Zoomed raw, smoothed, noise filtered, and N.L oscillation filtered pressure traces for n-heptane. (b) FFTs analysis for the raw, smoothed, noise filtered, and N.L oscillation filtered pressure signals.

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Fig. 16

Distillation curves for four fuels

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