Aamir Farooq's research while affiliated with King Fahd University of Petroleum and Minerals and other places
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Publications (264)
This work reports the mid-IR spectroscopy and reaction kinetics of 2-methyl-1,3-dioxolane (2M13DO). We carried out spectroscopic measurements to deduce temperature-dependent absorption cross-sections of 2M13DO over a broad wavelength range of 8.4–10.5 μm (950–1190 cm−1). For these measurements, we employed a rapidly tuning MIRcat-QT™ laser that can...
Direct-fired supercritical CO2 power cycles, operating on natural gas or syngas, have been proposed as future energy technologies with 100 % carbon capture at a price competitive with existing fossil fuel technologies. Likewise, blue or green hydrogen may be used for power generation to counter the intermittency of renewable power technologies. In...
A mid-infrared laser-based sensor is reported for the quantification of fugitive methane emissions. The sensor is based on a distributed feedback inter-band cascade laser operating near 3.3 μm. Wavelength tuning with cepstral analysis is employed to isolate methane absorbance from (1) fluctuations in the baseline laser intensity, and (2) interferin...
We present chemical kinetics and environmental monitoring applications in the long-wavelength mid-infrared (LW-MIR) region using a new diagnostic that exploits a widely tunable light source emitting in the LW-MIR. The custom-designed laser source is based on a difference-frequency generation (DFG) process in a nonlinear orientation-patterned GaAs c...
We report an approach for high-resolution spectroscopy using a widely tunable laser emitting in the molecular fingerprint region. The laser is based on difference-frequency generation (DFG) in a nonlinear orientation-patterned GaAs crystal. The signal laser, a CO 2 gas laser, is operated in a kHz-pulsed mode while the pump laser, an external-cavity...
Machine learning provides a set of new tools for the analysis, reduction and acceleration of combustion chemistry. The implementation of such tools is not new. However, with the emerging techniques of deep learning, renewed interest in implementing machine learning is fast growing. In this chapter, we illustrate applications of machine learning in...
Ignition delay times (IDTs) of iso-octane/air mixture were measured in a high-pressure shock tube and a rapid compression machine at ultra-lean (Φ = 0.2) to lean (Φ = 0.4 – 0.6) equivalence ratios, pressures of 20 – 40 bar, and temperatures of 630 – 1250 K. Measured IDTs were longer at lower equivalence ratio, and the equivalence ratio effect was m...
Novel shock tube experimental ignition delay time (IDT) data are provided to delineate the impact of high concentrations (45% by mole) of H2O and CO2 on IDTs of stoichiometric 4% H2. Ignition delay experiments were conducted using a high- and a low-pressure shock tube facility. High-pressure experiments were performed at pressures of 37-43.8 bar an...
We report an approach for high-resolution spectroscopy using a widely tunable laser emitting in the molecular fingerprint region. The laser is based on difference-frequency generation (DFG) in a nonlinear orientation-patterned GaAs crystal. The signal laser, a CO2 gas laser, is operated in a kHz-pulsed mode while the pump laser, an external-cavity...
Hydrogen cyanide (HCN) is a major source of prompt-NOx formation especially in fuel-bound nitrogen systems. To date, there is still a significant disagreement between experimental data and theoretical predictions of the rate coefficients of combustion reactions involving HCN as a prompt-NOx precursor. Accurate modeling of NOx formation would greatl...
In the study of chemical reactions, it is desirable to have a diagnostic strategy that can detect multiple species simultaneously with high sensitivity, selectivity, and fast time response. Laser-based selective detection of benzene, toluene, ethylbenzene, and xylenes (BTEX) has been challenging due to the similarly broad absorbance spectra of thes...
Cyclic saturated ethers are proposed as alternative fuels for future sustainability. In particular, dioxolanes have been identified as promising biofuel candidates. However, pyrolysis and oxidation of dioxolanes are not well understood. In this work, we measured the temperature-dependent absorption cross-section of 1,3-dioxolane (13DO) in the mid-I...
Cyclohexene is a common intermediate in the oxidation of cyclohexane and alkyl-substituted cyclohexanes. It also plays an important role in the formation of polycyclic aromatic hydrocarbons (PAHs) by providing a route for the first aromatic ring. Two types of reactions are highly important in cyclohexene kinetics, i.e., H-abstraction by OH radicals...
A mid-infrared laser-based sensor is designed and demonstrated for trace detection of benzene, acetylene, and carbon dioxide at ambient conditions. The sensor is based on a distributed feedback quantum cascade lase and a multidimensional liner (DFB-QCL) emitting near 14.84 um. Tunable diode laser absorption spectroscopy (TDLAS) and a multidimension...
Shock tubes are widely used in the study of chemical kinetics. Its benefits rely on the almost ideal shock-heating process that provides high temperatures and pressures to a chemical system for a limited test time. Just like any reactor, shock tubes are not immune to non-ideal effects. The study of conditions that might deviate experiments from ide...
Alkylated aromatics are ubiquitous in transportation fuels. 1,3,5-Trimethyl benzene (135TMB) is a popular surrogate for the aromatic content of distillate fuels due to its symmetry (point group, C3h), which facilitates the construction of an accurate chemical kinetic model. The reaction of OH radicals with 135TMB plays a crucial role in the oxidati...
Conjugated diolefins are not only crucial intermediates in larger hydrocarbon pyrolysis and oxidation, but also key species in the formation and growth of polycyclic aromatic hydrocarbons (PAHs). In this work, we employed a sensitive UV laser diagnostic to measure absorption cross-sections and decomposition rates of three conjugated diolefins, name...
A mid-infrared laser-based sensor is reported for the quantification of fugitive methane emissions. The sensor is based on a distributed feedback inter-band cascade laser (DFB – ICL) operating near 3.3 µm. Wavelength tuning with cepstral analysis is employed to isolate methane absorbance from (1) fluctuations in the baseline laser intensity, and (2...
Shock tubes have been routinely used to generate reliable chemical kinetic data for gas-phase chemistry. The conventional diaphragm-rupture mode for shock tube operation presents many challenges that may ultimately affect the quality of chemical kinetics data. Numerous diaphragmless concepts have been developed to overcome the drawbacks of using di...
Benefitting from the rapid development of instrumental analysis methods, intermediate products that were difficult to probe in the past can now be measured and quantified in complex reaction systems. To understand low temperature reactions of interest for combustion applications, and reduce the deviations between model predictions and experimental...
Accurate prediction of temperature-dependent reaction rate constants of organic compounds is of great importance to both atmospheric chemistry and combustion science. Extensive work has been done on developing automated mechanism generation systems but the lack of quality reaction rate data remains a huge bottleneck in the application of highly det...
![Fig. 7. Historical overview of photoacoustic spectroscopy [202-212]...](profile/Mohsin-Raza-3/publication/359808653/figure/fig2/AS:1157630349328386@1653011991361/Historical-overview-of-photoacoustic-spectroscopy-202-212-PA-photoacoustic-PAS_Q320.jpg)
Sensors are perhaps the most important and integral components of our modern society. With global warming and environmental pollution garnering ever-increasing attention, as well as solutions for sustainabile and smart cities, the optimized performance of current and future energy systems and process industries is paramount. The accurate sensing an...
The stability of anatase titania nanoparticles was investigated under exposure to repeated loading of shockwaves produced in a diaphragm-driven high-pressure shock tube. The titania samples were exposed to 20 shocks with pressure, temperature, and steady exposure time in the range of 20.5 – 26 bar, 1399 – 2101 K, and 1.74 – 1.83 milliseconds, respe...
Olefinic hydrocarbons are one of the main intermediates of the oxidation of large hydrocarbons, and they are also found in distillate transportation fuels. Combustion characteristics of olefinic species, particularly non-conjugated ones, are not well understood. This work reports chemical insights into the reaction of OH radicals with 1,4-pentadien...
This work reports laminar flame speeds and ignition delay times of 1,3-dioxolane/O2 /inert gases over a wide range of conditions. Laminar flame speeds were determined experimentally at pressures of 1 and 3 bar, the temperature of 300 K, and equivalence ratios ranging from 0.7 to 1.4 using a constant-volume spherical chamber, whereas ignition delay...
A mid-infrared absorption-based laser sensor is developed for selective and simultaneous benzene, toluene, ethylbenzene, and xylenes (BTEX) measurements under ambient conditions. The sensor is based on a distributed feedback inter-band cascade laser emitting near 3.3 µm. Wavelength tuning and deep neural networks were employed to differentiate the...
The presence of two functional groups (OH and double bond) in C5 methyl-substituted enols (i.e., isopentenols), such as 3-methyl-2-buten-1-ol (prenol) and 3-methyl-3-buten-1-ol (isoprenol), makes them excellent biofuel candidates as fuel...
Alkenes formed, during the refining of crude oil, by cracking the heavier fractions are present in transportation fuels in significant amounts, up to as much as 15–20% in gasoline. Moreover, alkenes are also the major intermediate products of the oxidation of alkanes, which play a significant role in autoignition chemistry. This review has assessed...
n-Propylcyclohexane (nPCH) is an important surrogate component for jet fuel, gasoline, and diesel. To comprehensively understand its combustion properties and chemical kinetics, ignition delay time (IDT) measurements of nPCH/air mixtures were performed in a high-pressure shock tube (HPST) at fuel-rich conditions (φ = 2.0), pressures of 10‒40 bar an...
This work presents the OH-initiated oxidation kinetics of 1,4-cyclochexadiene (1,4-CHD). The temperature dependence of the reaction was investigated by utilizing a laser flash photolysis flow reactor and laser-induced fluorescence (LPFR/LIF) technique over the temperature range of 295-438 K and a pressure of ∼50 torr. The kinetics of the reaction w...
Gasoline compression ignition (GCI) technology aims to improve internal combustion engine (ICE) efficiency. However, much is still unknown about the detailed combustion behavior of fuels under this novel ICE technology, such as relevant ignition temperature regimes and surrogate requirements under various engine load and speed conditions as well as...
A series of CeO 2 /Co 3 O 4 mixed nanocomposites with various Ce loading were fabricated by the pyrolysis of MOFs (metal organic frameworks), and their catalytic performance were evaluated by CO and C 2 H 4 oxidation reaction. The prepared catalysts inherited polyhedral morphology of ZIF-67 (Zeolitic Imidazolate Framework-67) nano-particles. By mea...
The reaction between phenyl radical and phenylacetylene is a prototype for the reactions of aryl radicals and alkynyl peri‑condensed aromatic hydrocarbons (PCAHs), which may help explain the dimerization of PCAHs by covalent bond with acetylene assistance. In this work, we have experimentally and theoretically investigated reaction kinetics of phen...
This work reports the temperature dependence of the rate coefficients for the reactions of atomic bromine with the xylenes that are determined experimentally and theoretically. The experiments were carried out...
In this work, we investigated the combustion characteristics of ammonia (NH3) by blending it with various proportions of diethyl ether (DEE). We measured laminar flame speed of various NH3/DEE blends (DEE, 10 - 40% by mole) using a constant volume spherical vessel at Ti = 298 K and Pi = 3 and 5 bar and Φ = 0.8 - 1.3. We developed a detailed kinetic...
A difference-frequency generation (DFG) laser is used to develop a diagnostic for HCN sensing near 14 μm. Pressure- and temperature-dependent absorption cross-sections are reported. The sensor is showcased in shock tube chemical kinetic experiments.
Correction for ‘Ethanolic gasoline, a lignocellulosic advanced biofuel’ by Mícheál Séamus Howard et al. , Sustainable Energy Fuels , 2019, 3 , 409–421, https://doi.org/10.1039/C8SE00378E.
A laser sensor is developed for simultaneous multi-species detection in high-temperature shock-tube experiments. It is based on a tunable DFB-ICL near 3.3 μm, off-axis CEAS and DNN for sensitive and selective measurements of target species.
We present a new sensor based on a widely tunable difference-frequency-generation light source emitting in the mid-infrared. We applied this sensor to probe benzene (C 6 H 6 ) and hydrogen cyanide (HCN) in reactive environments at combustion-relevent conditions.
A laser sensor is developed for methane measurements in environmental conditions. It is based on tuning an ICL near 3.3 µm and cepstral analysis to isolate methane absorbance from baseline intensity fluctuations and interfering absorbance.
Simultaneous multi-species sensing in shock tube experiments are performed using a single laser source. A tunable DFB-ICL emitting near 3.3 µm, off-axis CEAS, and DNN enabled sensitive and selective measurements of target species.
Alkylated cycloalkanes are vital components in gasoline, aviation, and diesel fuels; however, their combustion chemistry has been less investigated compared to other hydrocarbon classes. In this work, the combustion kinetics of n-propylcyclohexane (n-Pch) was studied across a range of experiments including pressurized flow reactor (PFR), jet stirre...
Ammonia (NH3) has recently received much attention as a promising future fuel for mobility and power generation. The use of ammonia as a fueling vector can help curb global warming by cutting CO2 emissions because it is a carbon-free fuel and a hydrogen carrier with a high percentage of hydrogen atoms per unit volume. Liquid ammonia contains a high...
Low-temperature oxidation of cyclohexane is investigated in two jet-stirred reactors (JSRs) at 1.04 bar and the equivalence ratio of 0.25. Reactive hydroperoxides and highly oxygenated molecules are detected using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The isomers of C6H10O (5-hexenal, cyclic ethers and cycloh...
Experimental and computational investigations are carried out to identify the generalized criterion to predict the preignition tendency of methanol and ethanol mixtures in shock tubes. Preignition or weak ignition in shock tubes has been reported to be a significant factor impacting the accuracy of the ignition delay times data. A systematic means...
Soot particles alter global climate and dominate the origin and evolution of carbonaceous interstellar material. Convincing experimental evidence has linked polycyclic aromatic hydrocarbons (PAH) to soot inception under low-temperature astrochemistry and high-temperature combustion conditions. However, significant gaps still remain in the knowledge...
α-Methyl-naphthalene is a very important intermediate in fuel oxidation and a raw material in industrial and scientific fields. Unraveling its detailed chemistry is important for its practical applications. Pyrolysis of α-methyl-naphthalene (C11H10) is studied in a flow reactor at low and atmospheric pressures (30 and 760 Torr) using synchrotron va...
α-Methyl-naphthalene plays an important role as a functional material in petrochemical industries and as a precursor of soot particles. The formation chemistry of polycyclic aromatic hydrocarbons (PAHs) from α-methyl-naphthalene, therefore, warrants detailed investigations. In this work, we studied PAH formation from its pyrolysis using experiments...
A model for the prediction of the derived cetane number (DCN) and carbon/hydrogen ratio (C/H) of hydrocarbon mixtures, diesel fuels, and diesel–gasoline blends has been developed on the basis of infrared (IR) spectroscopy data of pure components. IR spectra of 65 neat hydrocarbon species were used to generate spectra of 127 hydrocarbon blends by av...
The ν3 fundamental absorption band of methane (¹²CH4) dominates the 3.3–3.4 μm infrared spectral window and has been extensively used for atmospheric, planetary and astrophysical investigations. Spectroscopic data, such as line positions, line-strengths and foreign-collisional coefficients, are needed to analyze the infrared spectra of planetary at...
We present a detailed kinetic model for the oxidation of dimethyl ether (OME0) and dimethoxymethane (OME1) in presence of NOx. We further explored the effect of NOx chemistry on the oxidation kinetics of the two OMEs. Our kinetic model is validated against the recent flow reactor data. The results indicated that NO doping severely alters the oxidat...
Recent literature kinetic studies revealed the importance of new mechanisms for polycyclic aromatic hydrocarbon (PAH) and soot inception beyond hydrogen–abstraction–acetylene–addition (HACA) and hydrogen–abstraction–vinylacetylene–addition (HAVA) mechanisms in the combustion of ethylene and other hydrocarbons. Co-flow diffusion flame is a canonical...
Catalytic oxidation is the most efficient method of minimizing the emissions of harmful pollutants and greenhouse gases. In this study, ZrO 2-supported Pd catalysts are investigated for the catalytic oxidation of methane and ethylene. Pd/Y 2 O 3-stabilized ZrO 2 (Pd/YSZ) catalysts show attractive catalytic activity for methane and ethylene oxidatio...
![Fig. 1. Experimental facility [42] . Schematic diagram of flow reactor...](profile/Dapeng-Liu-8/publication/347454782/figure/fig1/AS:1037854805327880@1624455276979/Experimental-facility-42-Schematic-diagram-of-flow-reactor-combined-with-synchrotron_Q320.jpg)
Recent investigations illustrated that clustering of hydrocarbons by radical-chain reaction (CHRCR) mechanism provides key mechanistic steps for the rapid synthesis of polycyclic aromatic hydrocarbons (PAHs) and soot. Resonance-stabilized radicals (RSRs) play critical roles in this mechanism, and non-benzene first-ring species have attracted consid...
Bending modes metrology through a comb-referenced widely tunable nonlinear laser source is demonstrated. We report center frequencies of CO 2 lines determined with 30 kHz uncertainty and an extensive study of the n 11 band of benzene.
A laser sensor is developed for selective and simultaneous BTEX measurements. It is based on a DFB-ICL near 3.3 µm and deep neural networks (DNNs) to differentiate broad absorbance spectra of BTEX species.
Selective and simultaneous BTEX measurements are performed utilizing a 3.3 µm DFB- ICL. The sensor is based on wavelength tuning and deep neural networks (DNNs) to distinguish the broadband absorbance spectra of BTEX species.
We present a comb-calibrated, widely tunable laser spectrometer in the bending mode region applied for metrology-grade measurements on the ν 2 and ν 11 bands of CO 2 and benzene, respectively.
Laminar flame speed and autoignition properties of gasoline play key role in the overall performance of spark-ignition and modern engines. Since gasoline is a complex fuel containing hundreds of species, it is not feasible to model all components present in gasoline. Researchers tend to employ surrogates, comprising of few components, that mimic ta...
Blends of diesel and gasoline can be used to achieve certain desired ignition characteristics in advanced compression ignition engine concepts. In this work, ignition delay times were measured for two blends of diesel and gasoline in two shock tubes and in a rapid compression machine. These blends comprised of 50/50 and 25/75 volumetric% of diesel...
The reaction of Br atoms with toluene was investigated by employing various quantum chemical methods and statistical rate theory calculations. Various composite methods such as CBS‐QB3, G3, and G4 were used to obtain the energy profiles of the Br + toluene reaction. Further single‐point calculations of the stationary points were performed at the CC...
Binary blends of fast-reacting diethyl ether (DEE) and slow-reacting ethanol (EtOH) are quite promising as renewable replacements for conventional fuels in modern compression ignition engines. In this work, pure diethyl ether and a 50/50 M binary blend of diethyl ether and ethanol (DEE/EtOH) were investigated in a shock tube and a rapid compression...
Dibutyl ether (DBE) is a promising biofuel due to its high cetane number (~ 100) and high volumetric energy density (31.6 MJ/L). It could either be used directly in compression ignition engines or blended with other conventional or renewable fuels. Oxidation and pyrolysis kinetics of DBE are not well known, particularly at high pressures. In this w...
Optical metrology and high-resolution spectroscopy, despite impressive progress across diverse regions of the electromagnetic spectrum from ultraviolet to terahertz frequencies, are still severely limited in the region of vibrational bending modes from 13 to 20 µm. This long-wavelength part of the mid-infrared range remains largely unexplored due t...
Distillate fuels contain significant proportions of naphtheno-aromatic components and tetralin is a suitable surrogate component to represent this molecular moiety. The presence of aromatic and naphthyl rings makes kinetic modeling of tetralin very challenging. Primary radicals formed during the oxidation of tetralin can be aryl, benzylic or paraff...
Ammonia (NH3) is considered a promising carbon-neutral fuel, with high hydrogen content, that can diversify the global energy system. Blending ammonia with a highly reactive fuel is one possible strategy to enhance it’s combustion characteristics. Here, an investigation of blends of NH3 and dimethoxymethane (DMM), a biofuel with high fuel-born oxyg...
A mid-infrared laser-based sensor is designed and demonstrated for trace detection of benzene at ambient conditions. The sensor is based on a distributed feedback inter-band cascade laser operating near 3.3 μm and off-axis cavity-enhanced absorption spectroscopy. A multidimensional linear regression algorithm was applied to enable benzene measureme...
NOx mitigation is a central focus of combustion technologies with increasingly stringent emission regulations. NOx can also enhance the autoignition of hydrocarbon fuels and can promote soot oxidation. The reaction between allyl radical (C3H5) and NOx plays an important role in the oxidation kinetics of propene. In this work, we measured the absolu...
Cyclohexadienes (CHDs) are important intermediates in the pyrolysis and oxidation of many C6 cyclic hydrocarbons. Under combustion relevant conditions, these dienes may either eliminate H2 directly or lose H atoms sequentially to produce the first aromatic ring, i.e., benzene. This is one of the major reaction pathways for the formation of benzene...
Ammonia (NH3) is recognized as a carbon-free hydrogen-carrier fuel with a high content of hydrogen atoms per unit volume. Recently, ammonia has received increasing attention as a promising alternative fuel for internal combustion engine and gas turbine applications. However, the viability of ammonia fueling future combustion devices has several bar...
The reaction of acetaldehyde (CH3CHO) with hydroxyl radicals (OH) plays an important role in atmospheric and combustion chemistry. The low-temperature chemistry of this reaction has been studied widely in the literature. However, the branching of this reaction at high temperatures is not well known. Aiming to deduce the branching ratio of CH3CHO +...
![Fig. 12 The best designs from CFD [39] and ML-GGA for all operating...](profile/Pinaki-Pal-3/publication/342872967/figure/fig2/AS:929639065219072@1598654633336/The-best-designs-from-CFD-39-and-ML-GGA-for-all-operating-points-Journal-of-Energy_Q320.jpg)
![Fig. 13 Robustness of the best designs from CFD [39] and ML-GGA for all...](profile/Pinaki-Pal-3/publication/342872967/figure/fig3/AS:929639065190400@1598654633374/Robustness-of-the-best-designs-from-CFD-39-and-ML-GGA-for-all-operating-points_Q320.jpg)
![Optimum design properties from CFD, Ref. [25], and this work](profile/Pinaki-Pal-3/publication/342872967/figure/tbl1/AS:929639065202689@1598654633403/Optimum-design-properties-from-CFD-Ref-25-and-this-work_Q320.jpg)