Comparative Study on Spray Auto-Ignition of Di-n-Butyl Ether and Diesel Blends at Engine-Like Conditions

Abstract Di-n-butyl ether (DBE), a promising lignocellulosic biofuel, has been suggested as a potential alternative fuel for compression ignition engines. In this study, the spray auto-ignition characteristics of diesel/DBE blends were experimentally measured on a constant volume combustion chamber. Time-resolved pressure traces and heat release rates in fuel spray combustion were measured at changed fuel blending fractions, ambient temperatures, and oxygen concentrations. Further, ignition delay and combustion delay that evaluates fuel spray ignition tendency were derived and compared for different test blends. Experimental results indicated that fuel spray ignition tendency is promoted with DBE addition, evidenced by the advanced pressure rise and heat release processes, and the shortened ignition and combustion delays. Peak heat release rates are fuel-dependent at high ambient oxygen concentrations since the relative fractions of the premixed and diffusive burns alter with changed DBE addition. However, as the oxygen concentration drops to 11%, fuel effects on the peak heat release rates become less noticeable. Reduced ambient oxygen concentration effectively extends fuel ignition and combustion delays, and typical two-stage pressure rises and heat releases are observed for all test blends, as the oxygen concentration drops to 11%.

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Effects of Ambient Temperature and Oxygen Concentration on Soot Evolution in Diesel Spray Combustion

Volume 4 ◽

10.1115/ht-fed2004-56433 ◽

2004 ◽

Cited By ~ 2

Author(s):

Yi Xu ◽

Chia-Fon F. Lee

Keyword(s):

Ambient Temperature ◽

Heat Release ◽

Oxygen Concentration ◽

Heat Release Rate ◽

Release Rate ◽

Soot Formation ◽

Premixed Combustion ◽

Ambient Oxygen ◽

Lower Heat ◽

Soot Measurement

A newly developed Forward Illumination Light Extinction (FILE) soot measurement technique was applied in a constant volume spray chamber to study the effects of ambient temperature and oxygen concentration on soot evolution in diesel combustion. The FILE technique with the capability of two-dimensional time-resolved quantitative soot measurement provides the much-needed information to investigate the soot formation mechanism. The ambient temperatures of 1200K, 1000K and 800K were tested to study the temperature effects on soot formation. A decrease of ambient temperature results in a longer ignition delay, which promotes a larger premixed combustion zone combining with higher heat release rates. The change of ambient temperature from 1200K to 800K increases the fuel portion burnt in the premixed combustion period. At 800K, combustion is dominated by the premixed combustion and much less soot is formed. Diesel combustion with 21% and 15% ambient oxygen concentration was also studied. With lower ambient oxygen concentration, the combustion process is basically not changed, but expands into a longer time span with a lower heat release rate. The lower heat release rate results in a lower flame temperature, which benefits the NOx emission control. However, with about the same amount of soot within the flame, and much longer soot life, soot has more chance to escape to the exhaust.

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Influence of some factors on oxygen uptake of canine cardiac Purkinje fibers

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1963.204.1.5 ◽

1963 ◽

Vol 204 (1) ◽

pp. 5-8 ◽

Cited By ~ 15

Author(s):

Kalman Greenspan ◽

Paul F. Cranefield

Keyword(s):

Oxygen Uptake ◽

Oxygen Concentration ◽

Diffusion Limitation ◽

Purkinje Fibers ◽

Ambient Oxygen ◽

Cardiac Purkinje Fibers ◽

Lower Oxygen ◽

Wet Weight ◽

Oxygen Tensions ◽

Oxygen Concentrations

The rate of oxygen uptake of quiescent Purkinje fibers of the dog's heart was determined using a flow respirometer and oxygen polarography. At ambient oxygen concentrations of 60% or higher the rate of uptake was 0.739 mm3/mg wet weight per hr at 35 C. The temperature coefficient over the range 25–35° was 2.3. The uptake was independent of the ambient oxygen concentration at oxygen concentrations equal to or greater than 60% of an atmosphere. In lower oxygen concentrations the rate of uptake was found to be depressed. The depression of uptake in the lower oxygen tensions is probably the result of diffusion limitation; it may, however, reflect dependence of resting uptake on oxygen concentration.

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Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4026862 ◽

2014 ◽

Vol 136 (8) ◽

Cited By ~ 2

Author(s):

Mohammad Fatouraie ◽

Margaret Wooldridge

Keyword(s):

Heat Release ◽

High Speed ◽

Engine Performance ◽

Optical Investigation ◽

Release Rates ◽

High Speed Imaging ◽

Engine Operation ◽

Auto Ignition ◽

Spark Timing ◽

Combustion Properties

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from Φ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher net indicated mean effective pressure (IMEPn) and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 crank angle degrees (CAD) at lower engine speeds (700 rpm) and ∼11 CAD at higher engine speeds (1200 rpm). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to auto-ignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.

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Experimental study on the flame extension and risk analysis of a diffusion impinging flame in confined compartment

Journal of Fire Sciences ◽

10.1177/07349041211015766 ◽

2021 ◽

pp. 073490412110157

Author(s):

Aijuan Wang ◽

Brady Manescau ◽

Khaled Chetehouna ◽

Steve Rudz ◽

Ludovic Lamoot

Keyword(s):

Risk Analysis ◽

Heat Release ◽

Equivalence Ratio ◽

Fire Spread ◽

Critical Value ◽

Release Rates ◽

Flammability Limits ◽

Auto Ignition ◽

Extension Length ◽

Impinging Flame

In this work, an experimental investigation on a diffusion impinging flame in a confined compartment was performed. The objective was to study the influence of confinement on the behavior of a flame impinging the ceiling and to deduce the auto-ignition risk of the smoke produced in the confined compartment. For this, configurations with five confinement levels were constructed by the condition of windows and/or door in the compartment and the variation of the heat release rates was made between 0.5 and 18.6 kW. To evaluate the flame morphology and flame extension length, an image processing method based on the direct linear transformation algorithm and the fire segmentation algorithm was adopted. From the experimental data, it was shown that the heat release rate of 4.6 kW presents a critical value for the flame extension in confined configurations, which corresponds to the equivalence ratio of the enclosure greater than 1, highlighting an under-ventilated environment. In addition, an auto-ignition risk analysis of smoke with unburnt gas in the compartment was carried out. The concentration and temperature of these gases were compared to the lower flammability limits and the auto-ignition temperature. It was observed that there was auto-ignition risk of the smoke under the ceiling, especially in the confined compartment of equivalence ratio greater than 1. Under these conditions, it is possible to have a fire spread to another compartment.

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Modeling of Auto-Ignition and Combustion Processes for Dual-Component Fuel Spray

SAE International Journal of Engines ◽

10.4271/2011-24-0001 ◽

2011 ◽

Vol 4 (2) ◽

pp. 2193-2206 ◽

Cited By ~ 7

Author(s):

Yoshimitsu Kobashi ◽

Kenta Fujimori ◽

Hiroki Maekawa ◽

Satoshi Kato ◽

Daisuke Kawano ◽

...

Keyword(s):

Fuel Spray ◽

Auto Ignition ◽

Ignition And Combustion ◽

Combustion Processes

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The relationships between ambient oxygen concentration, temperature, body weight, and oxygen consumption for Mysis relicta (Malacostraca: Mysidacea)

Canadian Journal of Zoology ◽

10.1139/z80-145 ◽

1980 ◽

Vol 58 (6) ◽

pp. 1032-1036 ◽

Cited By ~ 10

Author(s):

I. M. Sandeman ◽

D. C. Lasenby

Keyword(s):

Body Weight ◽

Oxygen Consumption ◽

Oxygen Concentration ◽

Oxygen Consumption Rate ◽

Consumption Rate ◽

Mysis Relicta ◽

Ambient Oxygen ◽

Kootenay Lake ◽

Oxygen Concentrations

The relationships between ambient oxygen concentration, temperature, body weight, and oxygen consumption for Mysis relicta in Kootenay Lake, B.C. are examined. Mysis oxygen consumption rate declined with both decreasing temperatures and ambient oxygen concentrations.

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Tissue hypoxia inhibits prostaglandin and nitric oxide production and prevents ductus arteriosus reopening

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.279.1.r278 ◽

2000 ◽

Vol 279 (1) ◽

pp. R278-R286 ◽

Cited By ~ 18

Author(s):

Hiroki Kajino ◽

Yao-Qi Chen ◽

Sylvain Chemtob ◽

Nahid Waleh ◽

Cameron J. Koch ◽

...

Keyword(s):

Nitric Oxide ◽

Oxygen Concentration ◽

Ductus Arteriosus ◽

Tissue Hypoxia ◽

No Production ◽

Active Tension ◽

Tissue Oxygen ◽

Ambient Oxygen ◽

Inner Vessel ◽

Oxygen Concentrations

Regulation of ductus arteriosus (DA) tension depends on a balance between oxygen-induced constriction and PG and nitric oxide (NO)-mediated relaxation. After birth, increasing PaO2 produces DA constriction. However, as the full-term ductus constricts, it develops severe tissue hypoxia in its inner vessel wall (oxygen concentration <0.2%). We used isolated rings of fetal lamb DA to determine why the constricted ductus does not relax and reopen as it becomes hypoxic. We used a modification of the 2-(2-nitro-1 H-imidazol-1-yl)- N-(2,2,3,3,3-pentafluoropropyl) acetamide (EF5) technique (Clyman RI, Chan CY, Mauray F, Chen YQ, Cox W, Seidner SR, Lord EM, Weiss H, Wale N, Evan SM, and Koch CJ. Pediatr Res 45: 19–29, 1999) to determine mean tissue oxygen concentration. A decrease in the ductus' mean tissue oxygen concentration from 1.4 to 0.1% lowers the isometric tone of the ductus by 15 ± 10% of its maximal active tension (the maximal tension that can be produced by the ductus). Although decreases in oxygen concentration diminish ductus tension, most of the vasoconstrictor tone in the ductus is independent of ambient oxygen concentration. This oxygen-independent tone is equivalent to 64 ± 10% of the maximal active tension. At mean tissue oxygen concentrations >0.2%, endogenous PGs and NO inhibit more than 40% of the active tension developed by the ductus. However, when tissue oxygen concentrations drop below 0.2%, the constitutive relaxation of the ductus by endogenous PGs and NO is lost. In the absence of PG and NO production, tension increases to a level normally observed only after treatment of the ductus with indomethacin and nitro-l-arginine methyl ester (inhibitors of PG and NO production). Therefore, under conditions of severe hypoxia (tissue oxygen concentration <0.2% oxygen), the loss of PG- and NO-mediated relaxation more than compensates for the loss of oxygen-induced tension. We hypothesize that this increased ductus tone enables the vessel to remain closed as it undergoes tissue remodeling.

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