High-Speed Observation and Modeling of Dimethyl Ether Spray Combustion at Engine-Like Conditions

Advanced combustion systems that utilize different combustion modes and alternative fuels have significantly improved combustion performance and emissions compared to conventional diesel or spark-ignited combustions. As an alternative fuel, dimethyl ether (DME) has been receiving much attention as it runs effectively under low-temperature combustion (LTC) modes such as homogeneous charge compression ignition (HCCI) and reactivity control combustion ignition (RCCI). Under compression-ignition (CI), DME can be injected as liquid fuel into a hot chamber, resulting in a diesel-like spray/combustion characteristic. With its high fuel reactivity and unique chemical formula, DME ignites easily but produces almost smokeless combustion. In the current study, DME spray combustion under several different conditions of ambient temperature (Tamb = 750–1100 K), ambient density (ρamb = 14.8–30 kg/m3), oxygen concentration (O2 = 15–21%), and injection pressure (Pinj = 75–150 MPa) were studied. The results from both experiments (constant-volume combustion vessel) and numerical simulations were used to develop empirical correlations for ignition and lift-off length. Compared to diesel, the established correlation of DME shows a similar Arrhenius-type expression. Sensitivity studies show that Tamb and Pinj have a stronger effect on DME's ignition and combustion than other parameters. Finally, this study provides a simplified conceptual mechanism of DME reacting spray under high reactivity ambient (high Tamb, high O2) and LTC conditions. Finally, this paper discusses engine operating strategies using a non-conventional fuel such as DME with different reactivity and chemical properties.

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Effects of dimethyl-ether (DME) spray behavior in the cylinder on the combustion and exhaust emissions characteristics of a high speed diesel engine

Fuel Processing Technology ◽

10.1016/j.fuproc.2009.12.013 ◽

2010 ◽

Vol 91 (5) ◽

pp. 504-513 ◽

Cited By ~ 41

Author(s):

Su Han Park ◽

Hyung Jun Kim ◽

Chang Sik Lee

Keyword(s):

Diesel Engine ◽

Dimethyl Ether ◽

High Speed ◽

Exhaust Emissions ◽

High Speed Diesel

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Comparison of Flame Dynamics at Stable and Near-LBO Conditions for Swirl-Stabilized Kerosene Spray Combustion

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2015-42596 ◽

2015 ◽

Cited By ~ 1

Author(s):

Chi Zhang ◽

Pengfei Zou ◽

Bosen Wang ◽

Xin Xue ◽

Yuzhen Lin ◽

...

Keyword(s):

Reaction Zone ◽

High Speed ◽

Stable Condition ◽

Axial Direction ◽

Spray Combustion ◽

Flame Dynamics ◽

Major Mode ◽

The Difference ◽

Pod Analysis ◽

Rotation Motion

An experimental investigation was conducted to characterize the flame structures and dynamics at stable and near-lean blowout (LBO) conditions. The current experiments were carried out using a laboratory-scale aero-combustor with an internally-staged dome. The internally-staged injector consisted of pilot and main swirlers, and the pilot swirler was fueled with Chinese kerosene RP-3 while the main injector was chocked. The resulting spray flame was confined within a quartz tube under atmosphere pressure. In the present study, the influence of swirl intensity of the pilot swirler was also investiagted. The OH* chemiluminescence of the flame was recorded by a high-speed camera at a frequency of 2000 Hz. From the high-speed OH* images, the reaction zone was marked and the fluctuation of the reaction zone along axial direction was observed, showing that it became stronger at near-LBO condition than at stable condition. Proper Orthogonal Decomposition (POD) analysis was further used to provide insights into the characteristics of flame dynamics. Based on the POD results, the difference of the flame dynamics between the stable and near-LBO combustion was distinct. While the major Mode l of the flame under stable condition was rotation representing the rotation motion in the swirl flame, at near-LBO condition the flame dynamics included three modes — vibration, rotation, and flame shedding. In addition, for swirl-stabilized kerosene spray combustion investigated herein, the fluctuation of the reaction zone in axial direction became stronger with decreasing equivalence ratio when approaching LBO, and the POD analysis indicated that the Mode l of flame dynamics transitions from the rotation mode to the vibration mode. Although the change of pilot swirl number was found to have little influence on the Mode l of flame dynamics, it was noted to vary the fluctuation energy of the flame.

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Mixing effects of biogas and dimethyl ether (DME) on combustion and emission characteristics of DME fueled high-speed diesel engine

Energy ◽

10.1016/j.energy.2014.02.007 ◽

2014 ◽

Vol 66 ◽

pp. 413-422 ◽

Cited By ~ 39

Author(s):

Su Han Park ◽

Seung Hyun Yoon ◽

Junepyo Cha ◽

Chang Sik Lee

Keyword(s):

Diesel Engine ◽

Dimethyl Ether ◽

High Speed ◽

Emission Characteristics ◽

Mixing Effects ◽

High Speed Diesel

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Liftoff behaviors and flame structure of dimethyl ether jet flame in CH4/air vitiated coflow

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650919846007 ◽

2019 ◽

Vol 233 (8) ◽

pp. 1039-1046 ◽

Cited By ~ 1

Author(s):

Wei Fu ◽

Fengyu Li ◽

Haitao Zhang ◽

Bolun Yi ◽

Yanju Liu ◽

...

Keyword(s):

Dimethyl Ether ◽

High Speed ◽

Equivalence Ratio ◽

Flame Structure ◽

High Speed Photography ◽

Flame Stability ◽

Jet Flames ◽

Jet Flame ◽

Field Temperature ◽

Vitiated Coflow

The objective of this paper is to investigate the flame structure and liftoff behaviors of a dimethyl ether central jet in CH4/air vitiated coflow in a coflow burner. The liftoff behaviors of dimethyl ether jet flames in the air flow were studied firstly. The flame stability of the burner was analyzed by measuring the flow field temperature with thermocouples. By changing the coflow rate and CH4 equivalence ratio, the liftoff behaviors of dimethyl ether jet flames under different vitiated coflow environments were discussed. The jet flame structure was also analyzed qualitatively by high-speed photography.

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