Gas and Particulate Matter Products Formed in a Laminar Flow Reactor: Pyrolysis of Single-Component C2 Fuels

Abstract

Investigations that rank the tendencies of single-component fuels to form soot have given useful insights into how molecules and local molecular structure influences the conversion of carbon in fuel to soot. These studies can provide fundamental understanding of how functional group chemistry influences the products formed during pyrolysis or combustion. A series of experiments have been conducted which investigate the conversion of oxygenated and hydrocarbon C 2 molecules (ethanol, ethane, and ethylene) to particulate matter (PM) and other species (CO, CO 2 ). Single-component fuels have been tested in a laminar flow reactor at concentrations of 8000 ppmv, under pyrolysis conditions. Size and mass distributions of particulates are reported, measured by means of a differential mobility spectrometer (Cambustion DMS500).

Comparative Study on Nascent Soot Formation Characteristics in Laminar Premixed Acetylene, Ethylene, and Ethane Flames

“…Thus, it is of great research and practical value to have a clear understanding of the soot formation mechanism. The formation process is known as a transition from the gas phase to the condensed phase, involving polycyclic aromatic hydrocarbons (PAHs) formation, nucleation, coagulation, surface growth, and aggregation, , which are influenced by many factors such as temperature, − equivalence ratio (or carbon to oxygen (C/O) ratio), , fuel structure, − etc.…”

“…Their results indicated that the fuel structure had little implications on the critical sooting equivalence ratio with a given number of C–C bonds. However, extensive studies reported that detailed soot characteristics such as soot yield, , size distribution, , and morphology , are affected by fuel structure. Recently, more attention has been shifted to large molecule fuels that are close to practical fuels, yet the results can hardly be analyzed dating back to a specific fuel structure due to the complex molecular configurations and reaction pathways. ,, Meanwhile, it has been revealed that practical fuels would first decompose into small hydrocarbons such as methane, ethane, and ethylene in the combustors or engines. − As small hydrocarbons, C2 fuels (ethane, ethylene, and acetylene) have the merits for easy handling in experiments and relatively well-understood gas phase chemistry.…”

“…Over the last few decades, C2 fuels have been widely chosen as target fuels to investigate the soot formation process both experimentally ,,,, and computationally. − Takahashi et al and Harris et al explored the sooting tendency of C2 fuels using Bunsen-type flames and premixed flames, respectively. They concluded that for a fixed flame temperature, acetylene showed the earliest soot inception, while soot incepted the latest in the ethane flame as a function of the equivalence ratio.…”

“…Their results indicated that the fuel structure had little implications on the critical sooting equivalence ratio with a given number of C−C bonds. However, extensive studies reported that detailed soot characteristics such as soot yield, 12,17 size distribution, 11,18 and morphology 19,20 are affected by fuel structure. Recently, more attention has been shifted to large molecule fuels that are close to practical fuels, yet the results can hardly be analyzed dating back to a specific fuel structure due to the complex molecular configurations and reaction pathways.…”

“…In addition, these three fuels have the same number of carbon atoms but different types of carbon− carbon bonds (or carbon to hydrogen ratios), a typical feature of fuel structures. 9,16 Over the last few decades, C2 fuels have been widely chosen as target fuels to investigate the soot formation process both experimentally 10,12,17,26,27 and computationally. 28−31 Takahashi et al 27 and Harris et al 26 explored the sooting tendency of C2 fuels using Bunsen-type flames and premixed flames, respectively.…”