Kaoru Maruta

Kaoru Maruta
Tohoku University | Tohokudai · Institute of Fluid Science

Doctor of Engineering

About

196
Publications
13,840
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6,438
Citations
Citations since 2017
50 Research Items
2970 Citations
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500

Publications

Publications (196)
Preprint
Full-text available
The general relation between ignition and deflagration analyses was studied theoretically and computationally. Simple analysis showed that the temporal evolutions of normalized fuel mass fraction and the normalized temperature in a 0D homogeneous ignition are equivalent to the spatial evolutions of those in a 1D laminar premixed flame at Lewis numb...
Article
Full-text available
Ethylene carbonate (EC) and dimethyl carbonate (DMC) are important chemical substances of the lithium-ion battery (LIB) electrolytes. Although the carbonate esters are regarded as a cause of the LIB fires, there are few studies on the pyrolysis/combustion characteristics of EC. This study aims to investigate the pyrolysis characteristics of EC by p...
Article
Full-text available
To investigate (fuel-)lean/rich limits and essential stoichiometries, i.e., the borders of lean/rich combustion, one-dimensional steady computations with detailed chemistry for flame balls, counterflow flames, and stretch-free planar flames were conducted using a CH4/O2/Xe mixture that has been used in microgravity experiments. As continuous conver...
Article
The interactions between cool flames and flames with repetitive extinction and ignition (FREI) of stoichiometric n-heptane/air mixture were studied using a micro flow reactor with a controlled temperature profile from 373 to 1300 K. Two different flame dynamics with and without cool flames were observed in reactors with inner diameters dinner of 1...
Preprint
The Harrow, Hassidim, Lloyd (HHL) algorithm is a quantum algorithm expected to accelerate solving large-scale linear ordinary differential equations (ODEs). To apply the HHL to non-linear problems such as chemical reactions, the system must be linearized. In this study, Carleman linearization was utilized to transform nonlinear first-order ODEs of...
Preprint
The Harrow, Hassidim, Lloyd (HHL) algorithm is a quantum algorithm expected to accelerate solving large-scale linear ordinary differential equations (ODEs). To apply the HHL to non-linear problems such as chemical reactions, the system must be linearized. In this study, Carleman linearization was utilized to transform nonlinear first-order ODEs of...
Article
Full-text available
Effects of mixture composition and equivalence ratios on oxidation and reactivity of dimethyl ether (DME)/ammonia (NH3) mixtures are investigated based on weak flame responses observed in a micro flow reactor with a controlled temperature profile (MFR). For observations, the NH3 fractions in fuel blends are varied as 0–50%. Three equivalence ratios...
Article
Full-text available
Carbonate esters such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are widely used as electrolyte solvents in a lithium-ion battery (LIB) and are considered as one of potential fire causes. This study investigates a difference in gas-phase reactivities of DMC, EMC and DEC. Species measurements for oxidation...
Article
Full-text available
The direct use of n-butane in solid oxide fuel cell (SOFC) systems has been challenging due to high performance degradation and/or failure due to carbon deposition on the anode. Previous works have explored SOFCs with expensive integrated catalysts to promote the longevity of the SOFC, but few have achieved significant operating hours. In this work...
Article
Full-text available
Little is known on reactivity of ethyl methyl carbonate (EMC), which is widely used as an electrolyte solvent in lithium-ion batteries (LIB). A better understanding on the reactivity of EMC and its chemical kinetics are required to assess the fire risks of LIB. The reactivity of a stoichiometric EMC/air mixture was investigated with a weak flame in...
Article
Full-text available
Zero-dimensional computations of nanosecond-order ignition using a nanosecond discharge are performed with two constraints. The effects of these constraints are assessed to study the experimental rapid pressure change properly at the initial stages. The computations are carried out with the following constraints: constant internal energy and volume...
Article
Full-text available
High-temperature air combustion technology (HiCOT), which uses air preheated by heat recirculation, has had a great impact on reduction of CO2 and NOx emissions from combustion furnaces. In this study, a lab-scale test furnace was developed to examine the novel combustion method termed as high-temperature oxygen combustion, HiTOx. HiTOx uses combus...
Article
Full-text available
A two-dimensional laboratory-scale DNS of a knocking experiment using a stoichiometric n-C 7 H 16 /O 2 /Ar mixture at engine-like condition with the latest reduced SIP isooctane kinetics was conducted. A compressible reactive flow solver PeleC combined with an in-house efficient chemical kinetics solver MACKS was used. The results of DNS were compa...
Article
Full-text available
The present study aims to identify cross-reactions of methane and dimethyl ether (DME) at low temperatures. A weak flame in a micro flow reactor with a controlled temperature profile (MFR) for a stoichiometric methane/DME/air mixture with 90% CH4 and 10% DME (hereinafter expressed as 90%/10% CH4/DME) was used and analyzed. The weak flame structure...
Article
Full-text available
The effects of CO/H2/CH4 mixture compositions on the reactivity are investigated based on weak flame responses in a micro flow reactor with a controlled temperature profile (MFR). The ratios of H2 and CH4 are varied widely at a constant fraction of CO and the effects of variations in the compositions on the reactivity of the stoichiometric CO/H2/CH...
Article
Full-text available
To achieve highly efficient internal combustion engines, it is essential that the fuel and air mixtures in cylinder burn rapidly without making undesired 'knocking' phenomena. Fuel reactions should be fast enough for attaining sufficiently fast exothermic combustion for power output but simultaneously, it should be durable to the undesired knocking...
Article
Full-text available
The increase in production and decrease in cost of natural gas have made it a viable alternative fuel to petroleum and coal power-based systems. The thermal partial oxidation of natural gas has been investigated previously, but few have investigated the effects of lower concentration hydrocarbons on reforming characteristics; especially at low temp...
Article
The effects of NO on the oxidation and the reactivity of stoichiometric CH4/O2/Ar mixtures were investigated by weak flame responses in a micro flow reactor with a controlled temperature profile (MFR). The oxidation of CH4 was promoted and the reactivity of the CH4/O2/Ar mixture was enhanced as the NO concentration increased up to 948 ppm in both e...
Article
Full-text available
The R410A refrigerant (a blend of CH2F2 and C2HF5 with a mass ratio of 50:50) has been extensively used because of its small impact on the environment. We investigated the effects of the CH2F2-to-C2HF5 blending ratio in a stoichiometric CH2F2/C2HF5/air mixture on the ignition and combustion properties using a microflow-reactor with a controlled tem...
Article
Full-text available
For the understanding of ball-like flame behavior in counterflow field, transient three-dimensional computations with thermal-diffusion model were conducted for a low-Lewis number mixture near lean limit. Three types of flame behaviors were confirmed: stable spherical ball-like flame (spherical BLF) in A ≤ 0.010, stable non-spherical ball-like flam...
Article
Full-text available
Two-dimensional axisymmetric numerical simulation reproduced flames with repetitive extinction and ignition (FREI) in a micro flow reactor with a controlled temperature profile with a stoichiometric n-heptane/air mixture, which have been observed in the experiment. The ignition of hot flame occurred from consumption reactions of CO that was remaine...
Article
Full-text available
Productions of mono-/di-cyclic aromatic hydrocarbons as well as smaller stable species from extremely fuel-rich CH4/air mixtures (equivalence ratio of 1.7–6.0 and fuel-to-mixture ratio of 15–38 mol.%) near sooting limit in terms of temperature, were investigated using a micro flow reactor with a controlled temperature profile at maximum wall temper...
Article
Full-text available
Oxidation of C2HF5 (pentafluoroethane, R125) that has been extensively used as a refrigerant and fire suppressant agent was examined by weak flames in a micro flow reactor with a controlled temperature profile (MFR) for safety reasons. To investigate the oxidation process of a stoichiometric C2HF5/air mixture, species measurements for a stoichiomet...
Article
Thermal partial oxidation, or fuel-rich combustion, is a non-catalytic option for reforming hydrocarbons to synthesis gas for direct conversion in micro-Tubular Solid Oxide Fuel Cells (SOFCs). A number of studies have demonstrated the potential of using heat recirculation to sustain combustion at high equivalence ratios, where the concentration of...
Article
Full-text available
The effects of the addition of n-butanol on the formation of hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) of n-heptane combustions were investigated using a micro flow reactor (MFR) with a controlled temperature profile. The concentrations of small and large hydrocarbons, as well as PAHs were measured at a maximum wall temperature of 1,...
Conference Paper
Micro-combustion as a fuel reformer for solid oxide fuel cells has been studied with various smaller hydrocarbon fuels, such as methane and propane. n-Butane, due to wide accessibility in the world, is another potential fuel that could be reformed into syngas for power generation applications. The composition of micro-combustion exhausts of fuel-ri...
Poster
o Syngas generated from n-butane is significant (>40%) at high equivalence ratios (>2.5) if chemical equilibrium conditions can be obtained. 2. Experimental Design o The experimental setup of the micro-flow reactor with controlled temperature profile with an inner diameter of 3.6mm is shown below. o A micro-Tubular SOFC with an active area of 4 cm...
Article
The chemical and dilution effects of the major exhaust gas recirculation constituents N2, CO2 and H2O on the reactivity of iso-octane/air and n-heptane/air mixtures were investigated by separated weak flames in a micro flow reactor with a controlled temperature profile. Experimental results showed that high dilution ratios of 20% and 50% of N2 and...
Article
Aromatic formation in methane combustion is still not well understood. The first step to build kinetic models for aromatic formation is to understand fuel-rich oxidation and formation of aromatic precursors like acetylene and ethylene in varied temperature and equivalence ratio conditions. This understanding is also useful to optimize partial oxida...
Article
To examine methane oxidation at intermediate temperatures (ca., 900–1200 K), chemiluminescence observation and laser-induced fluorescence (LIF) measurements for CH2O and OH were conducted for methane weak flames in a micro flow reactor with a controlled temperature profile (MFR) at atmospheric and elevated pressures. Locations of CH2O–LIF, chemilum...
Article
The reactivities of n-heptane, n-pentane, PRF50, PRF80, iso-pentane and iso-octane were investigated by separated weak flames in a micro flow reactor with a controlled temperature profile at a pressure of 500 kPa. At this elevated pressure condition, low-temperature reactions in the cool flame and blue flame were enhanced. High temperature reaction...
Conference Paper
A micro flow reactor with controlled temperature profile was recently integrated with tubular Solid Oxide Fuel Cells (SOFCs) for reforming of hydrocarbons to syngas and cogeneration of heat and power. In this work, methane and natural gas are explored as potential fuels for this setup. Methane/air is found to have low reactivity in the micro flow r...
Article
Oxidation of CH2F2 (R32), a widely used refrigerant, was investigated experimentally and computationally using a micro flow reactor with a controlled temperature profile (MFR). Specifically, we examined weak flames of a stoichiometric CH2F2/air mixture in MFR observed at low flow velocities. In the case of the maximum wall temperature of 1300 K, we...
Article
Flame-assisted fuel cell (FFC) studies have been limited to lower fuel-rich equivalence ratios (∼1–1.7, due to the upper flammability limit and sooting limit) where only small concentrations of H2 and CO can be generated in the exhaust. In this work, a non-catalytic microcombustion based FFC is proposed for direct use of hydrocarbons for power gene...
Article
For establishing a new fuel reactivity index, characteristics of separated weak flames (cool, blue and hot flames) of PRF and C5 alkane isomers in a micro flow reactor with a controlled temperature profile at a pressure of 500 kPa were examined. Since cool and blue flames are enhanced compared to hot flame in low-to-intermediate temperatures at ele...
Article
Effects of n-butanol addition on the sooting tendency and formations of C1 and C2 primary intermediates of n-heptane/air mixtures were studied in a micro flow reactor with a controlled temperature profile. Sooting tendency was investigated over equivalence ratios of 1.5–4.0 at a maximum wall temperature of 1300 K. Experimental observations indicate...
Article
The reactivity of ultra-lean primary reference fuel (PRF)/air mixtures was investigated by weak flames in a vertical-type micro flow reactor (MFR) with a controlled temperature profile. In experiments, steady-separated weak flames were obtained at equivalence ratios between 0.5 and 1.0 for PRF80, 90, and 100. At leaner conditions, all the fuels sho...
Article
Wall chemical effect on DME/air weak flames (Uin = 1.5 cm/s, ϕ = 0.85) was investigated using a micro flow reactor with a streamwise temperature gradient experimentally. The quartz channel used in this study has a rectangular cross-section of 1.5 × 5 mm, which offers a good optical access for the planar laser-induced fluorescence (PLIF) measurement...
Article
To examine the effect of Lewis number on the extinction boundary, flame regimes, and the formation of sporadic flames, microgravity experiments on counterflow flames for CH 4 /O 2 /Kr (Le ≈ 0.7–0.8) and CH 4 /O 2 /Xe (Le ≈ 0.5) mixtures, and three types of computations, which are one-dimensional computations with a PREMIX-based code using detailed che...
Article
Full-text available
Download eprint: https://www.tandfonline.com/eprint/Q8hsZeyfCKUXVMqQEzfT/full Experimental and numerical results on premixed flame penetration and subsequent propagation in a multichannel burner are presented. The burner consists of the set of planar straight quartz channels which transverse sizes can be varied. It is found that, depending on mixtu...
Article
In the preface, we present a short overview of the papers included in the issue of Mathematical Modelling of Natural Phenomena 'Modelling in Ecology, Epidemiology and Evolution'.
Article
The experimental study of flammability limits of counterflow premixed methane-air flames in a planar micro channel is described in the paper. Combustion occurs in the gap between quartz plates which are connected with two countercurrent slot burners. The proposed counterflow burner allows investigation of the flame structure at low flow rates which...
Article
Laser-induced fluorescence (LIF) measurements were applied for the first time to a micro flow reactor with a controlled temperature profile to investigate general combustion and ignition characteristics of hydrogen (H2/O2/N2 mixture at O2:N2 = 1:9), methane, n-butane and dimethyl ether (DME) (fuel/air mixtures). For the hydrogen case, overall flame...
Article
A vertical-type micro flow reactor with a controlled temperature profile was used to investigate the effect of the equivalence ratio on low and high temperature reactions of ultra-lean gasoline surrogate/air weak flames. Surrogates of research octane number 90 and 100 were used at equivalence ratios between 0.50 and 1.00. In the experiments, leaner...
Article
Full-text available
Sooting behavior of premixed C1–C4 n-alkanes/air mixtures at maximum temperatures lower than 1400 K is studied experimentally using a micro flow reactor with a controlled temperature profile. Flame and soot responses to equivalence ratio (1.5–4.0) are observed for all mixtures. Critical sooting equivalence ratio observed for methane, propane and n-...
Article
To obtain an accurate and comprehensive understanding on the fuel-lean combustion limit, near-limit extinction boundary and flame regimes, experimental and numerical investigations using premixed counterflow flames were conducted for low-Lewis-number mixtures. Counterflow flame experiments were conducted under microgravity (2.2 ≦ a ≦ 12.9 s−1) and...
Article
Weak flame positions at various CO-to-H2 ratios in syngas combustion were investigated for stoichiometoric fuel (CO/H2) and oxidizer (O2/N2) mixtures at 1:7 O2:N2 using a micro flow reactor with a controlled temperature profile. In the case of low H2 mole fractions in fuel (0–10%), the experimental weak flame position significantly shifted to the l...
Article
Experiments and computations for CH4/O2/Xe and CH4/O2/N2 mixtures at ultra-lean conditions using a novel vertical micro flow reactor with a controlled temperature profile were conducted. The performance of several chemical mechanisms were evaluated at equivalence ratios 0.3, 0.5, and 0.7, and at different dilution ratios by observing the weak flame...
Article
Characteristics and spatial structure of premixed low-Lewis-number flames in stretched flow of two slot burners are studied numerically and theoretically in the frame of thermo-diffusive model with one-step chemical reaction. Three different combustion regimes are distinguished: twin planar flames, twin wrinkled flames and multiple flame tubes. In...
Article
Present paper is an attempt to illustrate a specific character of gas combustion and thermo-electrical processes in small-sized power energy-supply devices with thermoelectric methods of heat conversion. The efficiency of the heat conversion into electricity by using of thermo-elements embedded in the solid walls is estimated for a system with heat...
Article
A new system for converting combustion heat into electric power was proposed on the basis of countercurrent burner with thermoelectric element embedded in a wall separating incoming fresh mixture and combustion products. The wall serves as heat exchanger between combustion products and the fresh mixture. Numerical simulations showed that almost who...
Article
In this paper the dynamics of rich hydrogen–air flames in a microflow reactor with controlled temperature of the walls is investigated numerically using the thermal-diffusion model with two-step kinetics in one spatial dimension. It is found that as the parameters of the system are varied the sequence of bifurcation occurs leading to the formation...
Article
Fundamental combustion characteristics of lifted flames at high-temperature oxygen combustion conditions were investigated experimentally and numerically. Two types of the flame structures for lifted flames were identified by experimental flame images captured by a still camera with a CH band-pass filter as well as computations. One could be classi...
Article
Weak flames of four alkenes (ethylene, propylene, 1-butene and 1-pentene) were observed using a micro flow reactor with a controlled temperature profile to investigate their combustion and ignition characteristics. Weak-flame based investigation which enables to elucidate general ignition property of each fuel was conducted. One-dimensional computa...
Article
Dynamic behavior and 3D spatial structure of low-Lewis-number counterflow premixed flames are numerically studied in the frame of thermo-diffusive model with one-step chemical reaction. The diverse combustion regimes are described and regions of existence of these regimes in equivalence ratio/stretch rate plane are identified. Qualitative compariso...
Article
Full-text available
This paper presents combustion and ignition characteristic of H2/O2/N2 flames in a micro flow reactor with a controlled temperature profile. OH-LIF measurement was conducted to capture flame images. Flame responses were investigated for variable inlet flow velocity, U, and equivalence ratio, . Three kinds of flame responses were experimentally obse...
Article
OH-PLIF measurements and numerical simulations were conducted for co-axial laminar jet flame of CH_4/N_2 in high-temperature air (relevant to High-Temperature Air Combustion Technology: HiCOT) flow and that of CH_4/CO_2 in high-temperature O_2/CO_2 (High-Temperature Oxygen Combustion: HiTOx) flow. In both HiCOT and HiTOx conditions, two types of li...
Article
The effect of radical quenching on CH4/air flames was investigated using a micro flow reactor with a controlled temperature profile experimentally and numerically. To evaluate the radical quenching, two methods were employed in this study; changing the inner diameter of the reactor at atmospheric pressure, d; and changing pressure in the reactor, P...
Article
The very first successful experiments at elevated pressures up to 1.2 MPa by an “in-pressure-chamber”-type micro flow reactor with a controlled temperature profile are demonstrated. n-Butane was applied to the micro flow reactor and the ignition characteristics at pressures of 0.1–1.2 MPa were investigated by observing weak flames. Among three kind...
Article
Extinction limits of counterflow non-premixed flames with normal and high temperature oxidizers were studied experimentally and numerically for development of new-type oxygen-enriched mild combustion furnace. Extinction stretch rates of CH4/CO2 (at 300 K) versus O2/CO2 flames at oxygen mole fractions of 0.35 and 0.40 and oxidizer temperatures of 30...
Article
Sooting limits of n-hexadecane (n-cetane)/air and 2,2,4,4,6,8,8-heptamethylnonane (iso-cetane)/air mixtures were investigated using a micro flow reactor with a controlled temperature profile at equivalence ratios, ϕ, of 1.5–4.5, inlet mean flow velocities, U0, of 10–100 cm/s and atmospheric pressure. Result for n-cetane showed wider ϕ and U0 region...
Article
Low-speed counterflow flame experiments will be conducted at Japanese Experiment Module (JEM), Kibo, in the International Space Station (ISS) for constructing unified flammability theory. The subject was selected as an experimental theme in the latter half of the second utilization planning phase of Kibo. This paper presents theoretical background...
Article
Studies on flammability limits are briefly reviewed. Firstly, theory for describing combustion limit of planar propagating flame is introduced. Experimental methods to obtain flammability limits are then reviewed, namely the constant-volume bomb method and the counterflow flame method. Based on various studies, flammable regions of different types...
Article
A micro flow reactor with a controlled temperature profile was examined with regard to its capabilities to investigate soot formation characteristics of rich methane/air mixtures and the formation process of polycyclic aromatic hydrocarbons (PAHs) of rich acetylene/air mixtures. In the experiment for a methane/air mixture, four kinds of flame and s...
Article
Combustion and ignition characteristics of natural gas components such as methane, ethane, propane and n-butane were investigated experimentally and computationally using a micro flow reactor with a controlled temperature profile. Special attention was paid to weak flames which were observed in a low flow velocity region. The observed weak flame re...