The present work focuses on the analysis of the pulverized coal combustion aerodynamics of the dual swirl burner by the control of the swirl-modes such as the outer swirl intensity (OSI). The detailed structure of pulverized coal swirling flames with swirl-mode was studied experimentally by particle image velocimetry and local flame colors based on $OH^*$, $CH^*$, and ${C_2}^*$ radicals. For all co-swirling conditions, the internal recirculation zone (IRZ) was observed near the inner shear layer with respect to the processing vortex core structure. Furthermore, a co-rotating vortex in the outer shear layer and the exhaust tube vortex (ETV) along the central axis were observed. The intensity of $CH^*$ signal was higher with small coal particle size, conversely, the size of the distribution of the $CH^*$ signal becomes larger. Therefore, the control of the aerodynamics with changing swirl intensities may play an important role in improving both environmental and combustion performances.

A skeletal mechanism of coal combustion was derived from a detailed coal combustion kinetic mechanism through an importance analysis of chemical pathways. The reduction process consists of roughly two parts. The first process is performed based on a connectivity analysis between species. In this process, DRGEPSA is chosen for reduction process. Strongly connected species and related reactions from the important species set as start species by the operator are sorted into the reduced mechanism. About 70% of species and reactions can be removed with a limited accuracy loss. Subsequently the second reduction process, CSP, is performed. This method focuses on an importance of each reaction and can reduce a volume of mechanism appropriately. Through these analyses, a skeletal mechanism is generated that is including 65 species and 150 reactions. The generated skeletal mechanism is verified through a comparison with the detailed mechanism in the homogeneous reactor model of CHEMKIN-PRO under wide range of conditions. The generated mechanism can give an advantage in the analysis of coal combustion characteristics in detail in large scale simulations such as LES and DNS.

With the increasing trend in CFB(Circulating Fluidized Bed) boiler scale, the EHE(External Heat Exchanger) must be adopted to the large-scale boilers to recover insufficient heat transfer surface. In this study, the numerical analysis model for EHE in commercial 300MWe CFB boiler was developed with the inclusion of mechanistic model, which enables the heat transfer prediction. Finally, the calculated absorbed heat and derived heat transfer coefficient are evaluated through the verification with experimental data.

Boiler design should be desinged to maximize thermal efficiency of the system under imposed load requirement and a boiler should be validated for transient operation. If a proper prediction is possible on the transient behavior and transient characteristics of a boiler, one may asses the performance of boiler component, control logics and operation procedures. In this work, dynamic modeling method of boiler is presented and dynamic simulation of load runback scenario was carried out on suprecritical oil-firing boiler.

In the entrained-flow coal gasifier, coal ash turns into a molten slag most of which deposits onto the wall to form liquid and solid layers. Critical viscosity refers to the viscosity at the interface of the two layers. The slag layers play an important role in protecting the wall from physical/chemical attack from the hot syngas and in continuously discharging the ash to the slag tap at the bottom of the gasifier. For coal with high ash melting point and slag viscosity, CaO-based flux is added to coal to lower the viscosity. This study evaulates the effect of critical viscosity temperature and ash/flux ratio on the slag behavior using numerical modelling in a commercial gasifier. The changes in the slag layer thickness, heat transfer rate, surface temperature and velocity profiles were analyzed to understand the underlying mechanism of slag flow and heat transfer.

기후 변화에 대응하고 환경오염 물질 배출을 줄이기 위한 목적으로 화석 연료의 사용 감소와 이를 대체 할 수 있는 재생에너지 원 개발에 대한 연구가 다양하게 진행되고 있다. 화석 연료를 대체하는 재생 에너지원으로 선택되는 연료는 1차적 목적에 사용된 후 발생되는 공정 부산물 또는 사용 후 버려지는 폐자원들이다. 이러한 자원으로 폐 바이오매스 자원을 비롯하여 폐플라스틱, 하수 슬러지, 가축 분뇨, 저 등급 오일 등 종류가 다양하다. 이들 자원은 성상이 다양하고 발열량이 제각각 이며 생산량이 불특정한 단점을 가지고 있다. 이 중 저 등급 오일류는 고체상의 폐자원에 비하여 에너지 밀도가 높고 수송과 보관에 유리한 점이 있어 재생에너지원으로서 활용도가 높다.

The practical route for disposal of sewage sludge becomes energy recovery by combustion after its ocean dumping is banned in 2012 in Korea. Due to the high moisture content, however, sewage sludge is required to be dried before transport and combustion. In this study, pyrolysis and combustion characteristics of dried sewage sludge was investigated in a small-scale fixed bed reactor in order to provide fundamental data for energy recovery of the fuel. As the first step of combustion, the primary products of pyrolysis were analyzed in a fixed bed reactor for the condensable volatiles (tar), non-condensable gases, and char. For the combustion characteristics, another fixed bed reactor was constructed to monitor the weight and temperature of the fuel particles during ignition and combustion under different air flow rates. The test results were used to derive the ignition and burning rates.

Gasification of biomass produces syngas containing CO, $H_2$ and/or $CH_4$, which can then be converted into energy or value-added fuels. One of key issues for efficient gasification is to minimize tar concentration in the syngas for use in a final conversion device such as gas engine. This study investigated the decomposition of primary tar by catalytic cracking using char as catalyst, of which the feature can be integrated into a fixed bed gasifier design. The pyrolysis vapor containing tar from pyrolysis of wood at $500^{\circ}C$ was passed through a reactor filled with or without char at $800^{\circ}C$ for a residence time of 1, 3 or 5 sec. Then, the condensable vapor (water and tar) and gases were analyzed for the yields and elemental composition. Four types of char particles with different microscopic surface area and pore size distribution: wood, paddy straw, palm kernel shell and activated carbon. The results were analyzed for the mass and carbon yields of tar and the composition of product gases to conclude the effects of char types and residence time.

Capturing the carbon dioxide emitted from coal-fired power plants will be necessary if targeted reduction in carbon emissions is to be achieved. Modelling and simulation are the base for optimal operation and control in thermal power plant and also play an important role in energy savings. This study aims to analyze the performance of supercritical coal fired power plant through steady and dynamic simulation using a commercial software gCCS. A whole power plant has been modeled and validated with design data of 500 MWe power plant, base and part load operations of the plant were also evaluated, consequently it had been proven that the simulated result had a good agreement with actual operating data. In addition, the effect of co-firng on the plant efficiency and flue gases were investigated using gCCS simulator.

This study focused on the effect of the biomass blended ratio on air-staged pulverized coal furnace. The hybrid NOx reduction technology between fuel blending and air staging has been applied in an air-staged pulverized coal fired furnace. The results indicated that co-firing biomass with coal could reduce NOx emissions in an air-staged combustion. In addition, carbon burnout and flame temperature increased under the air-staged condition. A dominant synergistic effect on NOx reduction and carbon burnout was observed when biomass co-firing with coal was applied in air staged combustion.

발전소에서 설계 규격을 벗어나는 저등급 석탄을 사용하기 시작하면서, 보일러에서의 연소특성을 예측하기 어려운 다양한 성질의 석탄이 들어오게 되어 각종 연소 문제가 증가하고 있다. 이 중 약 점결 특성을 가지는 저등급 석탄의 사용은 대형 클링커로 인한 보일러 하부의 튜브 손상 사고, 재열증기온도 상승으로 인한 출력감발 등의 문제를 발생시켰다. 또한 현재 개발 중인 무회분석탄 역시 점결 특성을 가지고 있는 것으로 알려져 있어 보일러 내부의 다양한 문제를 일으킬 것으로 예상되고 있다. 발전소에서는 강점결탄 수입 규제를 위해 CSN(Crucible Swelling Number)를 이용하여 제철용으로 사용되는 강점결 석탄의 도입을 규제해왔으나, 발전소 운영에 악 영향을 미치는 약 점결탄에 대한 규제 및 대응으로는 그 효과가 미미한 실정이다. 따라서 본 연구에서는 석탄의 점결 특성 중 팽창 특성을 분석할 수 있는 Microdilatometer와 TGA를 이용한 연소반응성 분석을 통해 석탄의 점결 특성이 연소반응성에 미치는 영향을 분석하였다.

Predicting coal combustion by computational fluid dynamics (CFD) requires a combination of complicated flow and reaction models for turbulence, radiation, particle flows, heterogeneous combustion, and gaseous reactions. There are various levels of models available for each of the phenomena, but the use of advanced models are significantly restricted in a large-scale boiler due to the computational costs and the balance of accuracy between adopted models. In this study, the influence of coal devolatilization model and turbulent mixing rate was assessed in CFD for a commercial boiler at 500 MWe capacity. For coal devolatilization, two models were compared: i) a simple model assuming single volatile compound based on proximate analysis and ii) advanced model of FLASHCHAIN with multiple volatile species. It was found out that the influence of the model was observed near the flames but the overall gas temperature and heat transfer rate to the boiler were very similar. The devolatilization rate was found not significant since the difference in near-flame temperature became noticeable when it was multiplied by 10 or 0.1. In contrast, the influence of turbulent mixing rate (constant A in the Magnussen model) was found very large. Considering the heat transfer rate and flame temperature, a value of 1.0 was recommended for the rate constant.

We performed computational simulation for a heat recovery steam generator to predict emissions (especially carbon monoxide) and compare the results with experimental data. We used the steady laminar flamelet model(SLFM) which can consider detailed chemical mechanisms. To reduce the number of grid, we simplified the geometry of the whole heat recovery steam generator. In conclusion, the trend of simulation results is good agreement with experimental data.

The current paper introduce the flame transfer function calculation results using CFD in order to quantify the heat release fluctuations in a lean premixed gas turbine combustor. Comparisons of the modeled and measured flame shapes were made using the optimized heat transfer conditions.

The present study has numerically investigated the effects of the oxidizer-side nitrogen dilution on the precise structure and NOx formation characteristics of the turbulent syngas nonpremixed flames. Eulerian particle flamelet model was used to predicted the NOx formation characteristics in the turbulent syngas swirling nonpremixed flames. Current numerical simulation was conducted for the syngas gas turbine combustor. Numericla results indicate that as the H2O portion is increased in diluent, the formation of NOx decreased effectively in turbulent syngas swirl nonpremixed flames.

A Experimental study on flame extinction behavior was investigated using He curtain flow with counter triple co-flow burner. Buoyancy force was suppressed up to a microgravity level of $10^{-2}-10^{-3}g$ by using He curtain flow. The stability maps were provided with a functional dependency of diluent mole fraction and global strain rate to clarify the differences in flame extinction behavior. The flame extinction curves had C-shapes at various global strain rates. The oscillation and extinction modes were different each other in terms of the global strain rate, and the flames extinction modes could be classified into five modes such as (I) and (II): an extinction through the shrinkage of the outmost edge flame forward the flame center after self-excitation and without self-excitation, respectively, (III): an extinction through rapid advancement of a flame hole while the outmost edge flame is stationary, (IV): self-excitation occurs in the outermost edge flame and the center edge flame and then a donut shaped flame is formed and/or the flame is entirely extinguished, (V): shrinkage of the outermost edge flame without self-excitation followed by shrinkage or survival of the center flame. These oscillation and extinction modes could be identified well to the behavior of edge flame. The result also showed that the edge flame was influenced significantly by the conductive heat losses to the flame center or ambient He curtain flow.

The characteristics of the outward-propagating premixed flames of stoichiometric mixtures of R134a/methane/oxygen/nitrogen have been experimentally investigated in a constant volume combustion chamber. Three regimes of the expanding flames were categorized based on the flame behavior.

Spherically expanding flames are used to measure flame speeds, which are derived the corresponding laminar flame speeds at zero stretch. Flame speeds of n-butanol at high pressure are studied over an extensive range of equivalence ratios. The classical shadowgraph technique is used to detect the reaction zone. In analytical methodology the optimization process using least mean squares is performed to extract the laminar flame speeds. Laminar flame speeds are compared with results obtained from numerical work.

In this study, the laminar burning velocities of SNG fuel were studied using both experimental measurements and kinetic simulations. They were measured using the angle method of Bunsen flame configuration and the annular diverging channel combustor. And they were also numerically calculated by CHEMKIN Package with GRI 3.0 mechanisms. Spectrometer was used for characteristics of flame chemiluminescence of SNG fuels. From results of this work, first, we found that according to adding $H_2$ contents in the fuels the laminar burning velocities of SNG fuels were increased. And second, we also discovered existence of OH*, CH*, $C_2*$, HCO*, $CH_2*$ radicals and their correlation.

In this study, the nano-particle emitted from Gasoline Direct Injection(GDI) vehicles was measured using the Engine Exhaust Particle Sizer(EEPS) on a chassis dynamometer. In addition, driving mode were divided into cold start mode(CVS-75, NEDC) and hot start mode(NIER-6, NIER-9) to evaluated the characteristics in the various operating conditions. The Particle Number(PN) concentration was analyzed for various driving patterns, i.e., acceleration, deceleration, idling, cruising and the phases of mode. In a result, Total concentration of PN for size was concentrated from 50 to 100 nm and acceleration represents the highest concentration among the driving pattern. It is believed that the increases quantity of fuel, and mixture will be richer than other patterns.

The combustion and emission characteristics of propane and n-butane which are the main components of LPG were compared with gasoline. The experiment was performed in a stratified DISI engine under lean combustion conditions. Mixtures of propane and n-butane wre more homogeneous because propane and n-butane have better evaporation characteristics. As a result, combustion speeds of n-butane and propane were slower, and emission levels of NOx and PM were lower. However, in spite of better evaporation, PM from propane was higher.

Rising oil price and environmental problems are causing automotive industry to increase fuel efficiency. Improved fuel efficiency in gasoline engine was made possible by development of DISI gasoline engine. Since fuel is injected inside cylinder directly, in-cylinder temperature can be reduced than multi-port injection engine and this leads to increased compression ratio. However, engine performance is largely dependent on mixture formation process due to in-cylinder fuel injection. Especially for spray guided and air guided DISI gasoline engine, injection direction is important factor to mixture preparation. It is because interaction between intake flow and spray affect fuel-air mixture. Hence, in this study, mixture formation characteristics were analyzed by varying injection direction using KIVA 3V release2 code. Residual gas was considered for assuming combustion. Therefore, initial condition for in-cylinder temperature was set equal to the end state of exhaust stroke of combustion cycle. Since angle between intake air flow direction and spray direction affects fluid flow and evaporation field, mixture distribution was affected by fuel injection direction dominantly.

The effects of hydrogen ($H_2$) ratio on combustion and emission characteristics in a $H_2/diesel$ dual-fuel engine were investigated. Dual-fuel strategy was applied to improve the control of combustion phasing. The combustion phasing was retarded with increasing $H_2$ fraction. This can be explained by both reduced diesel concentration and chemical effect of $H_2$, which reduce the heat release rate during the low temperature reaction stage. Hydrocarbon and carbon monoxide emissions of the engine were decreased drastically when $H_2$ ratio was increased.

Through the economic development, people enjoying the camping and demand of camping goods are increasing since they have free time. So they use portable butane gas range outdoor. In addition to that, many restaurants that offer hotpot or meat in Korea use portable butane gas ranges for their convenience. But 19% of gas accidents are using portable butane gas range, 13.7% of them are using oversized cookware. Despite the high accident rate, there is no safety standards about portable butane gas range using oversized cookware. Therefore we conducted to measure temperature and pressure of portable butane gas ranges for reforming safety standards. As a result. we confirmed relation between bottom temperature of the portable butane gas barrel and pressure of the butane gas. Also we confirmed that portable butane gas ranges operate safely when bottom temperature of the portable butane gas barrel is bellow $50^{\circ}C$.

Exhaust gas boiler system with respect to national and international safety standards, comparative study best suited to the realities of local exhaust and exhaust system manufacturing, certification standards and gas boiler installation, management, and mip draft inspection standards will proceed through this study.

This study has been conducted for evaluation of qualitative/quantitative risk of HCNG filling station. In case of fire explosion occurred because of hydrogen, CNG, and HCNG leaking on same conditions, maximum overpressure was measured as 30kPa for hydrogen, 3.5kPa for HCNG, and 0.4kPa for CNG. The overpressure of HCNG was measured 7.75 times higher than that of CNG, but it was only 11.7% compared with hydrogen. When the explosion was occurred, in case of hydrogen, the measured influential distance of overpressure was 59m and radiant heat was 75m. In case of CNG, influential distance of overpressure was 89m and radiant heat was 144m would be estimated. In case of 30% HCNG that was blended with hydrogen and CNG, influential distance of overpressure was 81m and radiant heat was 130m were measured. As the explosion occurred with the same sized container that had 350bar for hydrogen and 250bar of CNG and HCNG, the damage distance that explosive overpressure and radiant heat influenced CNG was seen as the highest. HCNG that was placed between CNG and hydrogen tended to be seen as more similar with CNG.

Since 1st July 2012, the our Goverment and KOGAS have been adopting a calorific value range system from the standard calorific value system. Domestic power plant companies and KOGAS have asked GT manufacture about the effects of the reduction of the calorific value. We received GT manufacture's answer to the question on April 12.2011. Gas components of some GT models were limited to no more than 9% of the C2+ content. Now some of GTs remain under debating whether effects on variation of gas heating or not.

In general, high temperature combustion technique has been adopted as an efficient one. However, hydrocarbon-based fuel can be decomposed under high temperature, and it can affect the stabilization mechanism of edge flame. In this research, basic experimental study was conducted to identify the effect of fuel pyrolysis on the lift-off flame stabilization by changing the temperature of the plug flow reactor. Schmidt number of the gas fuel can be changed with temperature variation due to the fuel pyrolysis. Eventually, this study will help to establish and clarify the stabilization mechanism of lift-off edge flame.

Laminar lifted methane jet flame diluted with nitrogen and helium in co-flow air has been investigated experimentally. This paper examines the role of chemistry, intermediate species responsible for stabilization of lifted flame. To elucidate the stabilization mechanism in lifted methane jet flames with Sc<1, the chemiluminescence intensities of $CH^*$ and $OH^*$ were measured using ICCD camera at various nozzle exit velocities and fuel mole fractions. It has been observed that the $OH^*$ species can play an important role in stabilization of lifted methane jet flame as they are good indicators of heat release rate which can affect on flame speed and increase stability through reduction in ignition delay time.

A study on laminar coflow jet flames diluted with helium and nitrogen has been conducted to investigate self-excitations. The stability map was provided with a function of nozzle exit velocity and fuel mole fractions of propane or methane. The results show that there exist three types of self-excitations; (1) buoyancy-driven self-excitation (BDSE), (2) Lewis number induced self-excitation coupled with buoyancy (LCB) and (3) Lewis number induced self-excitation (LISE).

The full transport equation approach for laminar non-premixed flame with detailed chemistry, soot and radiation has an advantage in accuracy and describing for emission pathway, but this approach requires the excessive computational cost especially for a higher-order hydrocarbon fuel flames. On the other hand, the standard flamelet model has an efficiency and accuracy for non-premixed flame, though this model is not suitable for simulating slow processor like soot and radiation in laminar non-premixed flame situation. To overcome this limitation, modified transient flamelet model is developed which coupled with two-equation soot model involved in soot formation and evolution mechanism such as nucleation, surface growth, oxidation and agglomeration.

Excess enthalpy flame propagating an porous inert medium, which recirculate exhaust heat to the upstream cold mixture, is theoretically analyzed. Using the activation-energy asymptotics, the flame structure is divided into the thin reaction and the gas-phase preheat zone, as is traditionally done. Ahead and behind of the two, there exist an outer preheat zone, where heat is convectively transferred from solid to gas, and a downstream re-equilibrium zone, where thermal equilibrium between phases is established. Asymptotic solutions of species and energy equations in each zone are obtained and then matched to each other, and finally the mass burning rate is obtained as a function of the flame propagation velocity with respect to the solid phase and physical properties of gas and solid.

Stabilization characteristics of highly $N_2$-diluted $CH_4-O_2$ flame in an axially two-section porous inert medium were experimentally investigated for its application to the waste gas scrubber in semiconductor manufacturing processes. The flame behaviors were observed with respect to the fuel and $N_2$ flow rates and the equivalence ratios. As a result, four kinds of flame behaviors such as stable, flashback crossing the interface, blowout and sudden extinction were observed.

This numerical study was carried out to optimize dual fuel combustion on natural gas-diesel in static chamber. Spray experiments conducted under conditions of premixed methan 0%, 5% and 10%. In the results, penetration decreases when premixed methane is increasing. Constants of numerical models were acquired from results of spray experiments to enhance accuracy of numerical study. And dual fuel engine simulation was implemented by using AVL-FIRE with acquired constants.

The demand of diesel engine on the construction equipment has been rapidly increased because of thermal efficiency and power. But some of the construction equipment is imported from other country, since the their demands are not so large as compared with the other construction equipment. The imported construction equipments will be tested for emission with standard measurement mode. This study was conducted to measure emission characteristics of the construction equipment with changed standard measurement experimentally.

This article describes an investigation of flame stability characteristics with various compositions of synthetic natural gas (SNG) in dual swirl combustor. The objective of this study is to investigate the flame stabilization, flame structure, fuel compatibility using chemiluminescence measurement in SNG with varying fuel compositions. As experimental conditions, hydrogen content was adjusted from 0 to 11%. Experimental results show that the addition of hydrogen has a major effect on flame behavior due to the higher burning rates associated with hydrogen consequently, The higher reaction activity of hydrogen has extended lean blow-off limit. Especially, DI flame limit has improved more 12.1%.

The blowoff phenomenon was experimentally investigated in a ducted combustor according to the acoustic excitation. The blowoff equivalence ratio rapidly increases at specific acoustic excitation frequencies. A resonance phenomenon occurs when the excitation frequency approaches the harmonic frequency of the combustor. The resonance increases the velocity fluctuation in the combustor and the infiltration velocity of the unburned gas in the shear layer. Consequently, the mixture velocity exceeds the burning velocity and the blowoff occurs at the higher equivalence ratio.

This study was aimed to assess combustion stability for coaxial swirl injector and FOOF impinging injector which would be candidates in liquid rocket engine combustors. Simulating combustion tests under atmospheric condition have been conducted by gaseous oxygen and the mixture of methane and propane, using two actual injectors. By analyzing the measured dynamic pressure signals, we have evaluated the combustion stability margin of both injectors by drawing a stability map.

This article describes an investigation of basic combustion characteristics of radiant burner with various firing rate and equivalence ratios in porous metal. As a main experimental condition, firing rates and equivalence ratios each were adjusted from 204 to $408kW/m^2$ and 0.6 to 1.3. The purpose of this study is to investigate radiation efficiency using two experiment methods. The first way is to calculate the radiation efficiency by measuring the temperature of the burner surface, and the second is to compute the radiation efficiency by measuring the radiation intensity of the burner surface with a radio meter. The value of the radiation efficiency did not exactly match in the two cases. But we figured out that in accordance with increasing heat power, radiation efficiency was decreased. And additional complementary experiment on the relationship between these values is needed.

The feasibility of a molten metal as a bed material of a pyrolysis system was investigated. The molten metal has various advantages such as high thermal conductivity, wide operating range and low viscosity. Tin was selected since its physical characteristics are suitable for the purpose. As a results, it was found that pyrolytic oil yield and reaction rate were significantly enhanced with the molten Tin. In addition, oxygen component of the product oil was decreased due to Tin oxidation.

The application of particle reaction model in the packed bed process modeling is discussed for iron ore pellet induration process. Combustion of coke breeze in the pellet is estimated by using shrinking unreacted-core model and grain model in which the progress of chemical reaction is described in different concepts. Under the identical inlet gas and solid conditions, the calculation using shrinking core model showed deviated results in terms of temperature profile and conversion fraction, which may imply the significance of selecting proper particle reaction model in consideration of particle characteristics and process operation conditions.

Detonation propagation studies is recently getting more attention in these days for its feasibility in aerospace application. Another motivation for this study is the safety concern in industries, since the detonation can cause failure to the mechanical components particularly when the flame accelerates within a pipe or tubes. In this study we numerically simulated a Moderately unstable detonation case with various grid systems and fluid dynamic length scales and have compared in the contents. Moderately Unstable detonation case was selected for this study and detailed Hydrogen-Air Reaction Mechanisms proposed by Jachimowski was used in this study with N2 as inert species.

The flame cell dynamics in 2-D opposed nonpremixed tubular configuration was investigated using high-fidelity numerical simulations. The diffusive-thermal instability occurs as the $Damk{\ddot{o}}hler$ number, Da, approaches the 1-D extinction limit of the tubular flames and several flame cells are generated depending on Da, and flame radius. In general, the number of flame cells are found close to the largest wave number from the linear stability analysis. It was also found from the displacement speed analysis that during the local flame extinction and cell formation, negative edge flame speed is observed due to small gain from reaction compared to large loss from diffusion.

A comparative DNS study of the ignition characteristics of dual-fueled reactivity controlled compression ignition (RCCI) and stratification charge compression ignition (SCCI) is investigated using a 116-species reduced primary reference fuel (PRF) mechanism. In the RCCI combustion, two PRF fuels (n-heptane and iso-octane) with opposite autoignition characteristics are separatedly supplied and in-cylinder blended such that spatial variations in fuel reactivity, fuel concentration and temperature are achieved. In the SCCI combustion, however, just a single fuel (PRF50) is used such that only fuel concentration and temperature inhomoginieties are obtained. Because three factors, rather than only two as in SCCI combustion, govern the overall RCCI combustion, combustion timing and combustion duration or heat release rate of RCCI combustion are flexibly and effectively controlled. It is found that the overall RCCI combustion occurs much earlier and its combustion duration is longer compared to SCC combustionI. Moreover, the negative temperature coefficient (NTC) has a positive effect on enhancing RCCI combustion by inducing a shorter combustion timing and a longer combustion duration as a result of the occurrence of a predominant low-speed deflagration-combustion mode.

The multi-environment probability density function model has been applied to simulate the turbulent stratified premixed flames. The direct quadrature method of moments (DQMOM) has been adopted to solve the transport PDF equation due to its computational efficiency and robustness. Computations are made for the non-swirling turbulent stratified premixed flames including SWB1, SWB5 and SWB9. The numerical results obtained in this study are precisely compared with experimental data in terms of axial velocity, unconditional means and conditional means for scalar field including temperature and species mass fraction.

The multi-environment probability density function model has been applied to simulate the turbulent stratified premixed flames. The direct quadrature method of moments (DQMOM) has been adopted to solve the transport PDF equation due to its computational efficiency and robustness. The IEM mixing model is employed to represent the mixing process and the chemical mechanism is based on Gri 3.0 mechanism. Numerical results obtained in this study are precisely compared with experimental data in terms of unconditional and conditional means for scalar fields and velocity fields.

An experimental study on downwardly and upwardly spreading flames over slanted electrical wire, which is insulated by Polyethylene(PE), was conducted with applied AC electric field. The result showed that downwardly and upwardly spreading flames with angle of inclination leaned toward burnt side and unburned side, respectively. With applied AC electric fields, size of downwardly spreading flame decreased slightly and that of upwardly spreading flame increased significantly. Flame spread rate showed various trends in terms of inclination, applied voltage and frequency.

The characteristics of laminar free jet flow with having applied AC electric fields have been investigated experimentally. A single electrode configuration was adopted such that electric fields were applied directly to nozzle and thus the surrounding could be an infinite ground. The experimental results showed that the jet flow with AC was modified significantly. At a certain axial distance, the laminar fuel stem was broken down and subsequently it was separated into three parts when AC electric fields were applied over a certain voltage in a range of frequencies less than 120 Hz. The breakdown point was measured by varying applied AC voltage and frequency. The effect of applying electric fields to jet flow was discussed in detail.

$Fuel/N_2$ and fuel/air mixtures were treated with non-thermal DBD plasma and the changes in characteristics of laminar diffusion flame have been observed. Flame of $Fuel/N_2$ mixture generated more soot under plasma condition while less amount of soot was formed from fuel/air mixture flame. Luminescence spectrum and gas chromatography results confirmed that plasma energy converts a fraction of fuel molecules into radicals, which then form $C_2$, $C_3$, $C_4$ and higher hydrocarbon under no oxygen condition or turn into CO, $CO_2$ and $H_2O$ when oxygen is present.

This paper is suggesting about glass melting technology, using both plasma and combustion heat source. The mixed flame was formed to flow pattern of turning by plasma and combustion in melting zone. The burning time was extremely extended for vitrification of raw materials in melting zone, as a result, meting time was significantly reduced. This system was designed to smaller size than existing glass melting facilities. We had achieved to 30% energy saving, due to reduce residence time of melted materials inside furnace.

The potential of combustion treatment of low concentration VOC on a turbulent partially premixed flame has been studied experimentally. The significant decrease in hydrocarbon concentration from the low concentration VOC was observed with a turbulent partially premixed flame. The VOC/inert gas mixture whose fuel concentration is beyond the flammability limit could be treated in this method.

Simultaneous measurements of planar laser-induced fluorescence (PLIF) of OH radicals and particle image velocimetry (PIV) were used to investigate the strain rates and OH structure characteristics of turbulent syngas non-premixed jet flames close to blowoff. Mean values of the maximum principal strain rate on OH layer decreases with the axial distance, and its standard deviation is significantly large upstream. Strain rate on stabilization region of the stable flame is only about a half of that of the flame near blowoff.

High combustion efficiency of hydrogen could make it an ideal source of green energy in the future. At this time, high pressure vessel is the most reasonable method of storing hydrogen. However, such a high pressurized vessel could pose a critical threat if ruptured. For this reason, it is important to understand the mechanism of hydrogen's self-ignition when a high-pressure hydrogen released into air. This paper presents several visualization images as experimental results using high-speed camera. From the visualization images, the ignition is initiated near rupture disk immediately after failure of disk. And the initial ignition and flame is stronger as a rupture pressure increases. However, this ignition region do not affect the general self-ignition mechanism when a high-pressure hydrogen is released into air through tue after failure of disk.

The flame chemiluminescence is a good tracer of flame statement. In this study, the characteristics of flame chemiluminescence($OH^*$, $CH^*$, ${C_2}^*$) according different measuring locations using photomultiplier(PMT), spectrometer and CCD camera. Measurements are made for $OH^*$, $CH^*$, ${C_2}^*$ radicals in gas & light oil diffusion flames. At turbulent nonpremixed combustion mode, the equivalence ratio is varied. The experimental results showed that measuring location affects the result of flame chemiluminescence.

An experimental study has been conducted to investigate the heat transfer characteristics of syngas/air mixture impinging jet flame with 10% hydrogen content. Effects of impinging distance, Reynolds number as major parameters on surface temperature of stagnation point were examined experimentally by the data acquisitions from k-type thermocouple. There were 2 times of maximum peak point of stagnation point with respect to the impinging distance for the investigation. As reynolds number increases, the nusselt number and convective heat transfer coefficient increased accordingly.

Lean-rich combustion system was composed both fuel-lean and fuel-rich flame at once. Each of fuel-lean and fuel-rich combustion types to reduce Thermal $NO_x$ and obtain flame stability. This study was confirmed a stability of flame through variation of flame shape that EGR was applied and compared the emission characteristics of EGR lean-rich combustion system to normal premixed combustion system at real condition to review a utility of the system. As a result, emission index of $NO_x$ and CO generated from EGR lean-rich combustion system at global equivalence ratio is 0.85 just half level($NO_x$ 0.31 g/kg, CO 0.08g/kg) compared to the amount generated from normal premixed combustion system at equivalence ratio is 0.78.

An experimental study has been carried out to investigate a thermal decomposition of urea solution at relative low temperature with a lab-scaled exhaust pipe. The conversion efficiency of reductant considered with both ammonia and HNCO related with the urea injection quantity, inflow gas velocity and temperature. The conversion efficiency of ammonia was larger than that of HNCO under all experimental conditions unlike the theoretical thermolysis reaction.

A correlation between an air inflow velocity and $NO_x$ emission is investigated numerically. The area of a swirl premixed burner is controlled geometrically to increase or decrease an air inflow velocity. When an air velocity increases, mixedness at the burner exit is improved and NO emission at the liner exit is reduced. Although the area of an air slit is the same, NO emission shows discrepancy due to difference of air slit shapes.

The opposed flow flame in a mesoscale channel was constructed to observe the flame stabilization behaviors at low strain rate conditions (<$10s^{-1}$). The purpose of this study is to get the overall flame behaviors of partially premixed flames with oxygen enhanced conditions at low strain rates. The oxygen ratio in oxidizer was changed from 18 to 30 %. Conclusively, the flame extinction limit approached to about $1s^{-1}$, and divided into three representative regimes corresponding to self propagating flame, transitional flame, quenching flame regimes.

Synthesis gas such as hydrogen and carbon monoxide was produced from $CH_4//oxygen$ mixture using two-section porous media combustor. Heat recirculation through the inner foam structure could extend the flow velocity of stable region over the laminar burning velocity. $H_2/CO$ ratio and module M from concentration of flue gas measured by Gas Chromatography was similar to those calculated by equilibrium. But it was made sure that the heat loss effect becomes more influential than heat recirculation effect as the mixture gets richer. To generate synthesis gas appropriate for methanol production, insulated pressurized porous media combustor will be designed and built in the future.

지구온난화 문제는 한국가의 문제가 아니라 인류의 문제로 대두되어 많은 이에대한 많은 연구가 이루어 지고 있다. 지구온난화의 주 대상물질인 화석연료로부터 연소시 발생하는 이산화탄소를 감축하기위한 많은 규제와 노력이 요구된다. CCS(Carbon Capture & Storage)란 화석연료로 부터 연소시 대기 중으로 배출되는 온실가스($CO_2$)를 포집하여 재생 또는 지중, 해양에 저장하는 기술로서 국가녹색성장 핵심기술중의 하나로 분류되며, $CO_2$ 회수방안, 저장, 처리관련 연구를 비롯하여 국내외 적으로 활발한 연구가 이루어 지고 있다. 또한 순산소 연소기술을 통한 $CO_2$ 회수, 처리기술은 연료의 산화제를 공기대신 순도 95% 이상의 고농도 산소를 이용하여 순산소연소를 하며, 이때 발생하는 배가스의 대부분은 $CO_2$와 수증기로 구성되어 있다. 발생된 배가스의 약 70~80%를 다시 연소실로 재순환시켜 연소기의 열적 특성에 적절한 연소가 가능하도록 최적화함과 동시에 배가스의 $CO_2$ 농도를 80% 이상으로 농축시켜 회수를 용이하게 하며, 동시에 공해물질은 NOx 발생량을 10ppM 이하로 줄일 수 있는 기술이다. 천연가스를 생산하는 LNG기지에서 연소에 의한 이산화탄소를 발생시키는 기기로는 수중연소식기화기(SMV ; Submerged Combustion Vaporizer)를 들 수 있다. SMV는 버너를 이용하여 $-162^{\circ}C$ LNG를 $10^{\circ}C$의 LN로 기화시키는 설비로서 특히 동절기에 작동시키며 $CO_2$를 배출시키는 연소기다. 본 연구에서는 수중연소식 SMV에 순산소 연소방식을 적용하여 천연가스와 산소를 연소시키므로서 발생되는 $CO_2$를 LNG냉열을 이용 액체화 시켜 회수하는 연구를 수행하고 있다. 내용중에 수중연 소식 SMV에 대한 순산소 연소기를 개발하는 연구를 수행하였으며, 실제 SMV의 1/10크기, 열량기준 1/900로 모형을 제작하여 실험하였다. 연소기 노즐 은 직경 0.6mm, 배가스가 수조내에서 48개의 노즐을 제작하였다. 실험결과 일정량 이상의 $CO_2$ EGR율이 일정 값 이상이 되면 화염의 길이가 공기/NG 화염 길이와 큰 차이가 없었으며 $CO_2$ EGR율이 100%이상에서는 $CO_2$ EGR율 증가에 따른 화염길이 변화는 크게 나타나지 않았다. CO 배출 농도는 공기/NG 연소의 경우보다 높게 나타났으며, ${\lambda}$가 1.4보다 높은 조건에서는 측정되지 않았다. NOx의 배출 농도는 약 1~8ppm으로 나타났다.

The installation of light oil facilities or delayed cokers seems to be inevitable in the oil refinery industry due to the heavy crude oil reserves and the increased use of light fuels as petroleum products. Petroleum coke is a byproduct of oil refineries and it has higher fixed carbon content, higher calorific value, and lower ash content than coal. However, its sulfur content and heavy metal content are higher than coal. In spite of disadvantages, petroleum coke might be one of promising resources due to gasification processes. The gasification of petroleum coke can improve economic value of oil refinery industries by handling cheap, toxic wastes in an environment-friendly way. In this study, $CO_2$ gasification reaction kinetics of petroleum coke, various coals and mixing coal with petroleum coke have investigated and been compared by using TGA. The kinetics of $CO_2$ gasification has been performed with petroleum coke, 3 kinds of bituminous coal [BENGALLA, White Haven, TALDINSKY], and 3 kinds of sub-bituminous coal [KPU, LG, MSJ] at various temperature[$1100-1400^{\circ}C$].

Low temperature pyrolysis of woody biomass has been conducted to produce highcalorie torrefied fuel. In this experiment, to maximize the energy efficiency in heat transfer, flue gas is directly used for heat source in the torrefier. To accomplish the oxygen free environment in the torrefaction reactor, a burner has been developed and it can be runned with fuel rich state. An inner central axis rotating type of reactor was applied in experiment. To use the calorific gases produced from torrefier, another burner is developed to combust them.

Due to global economic growth, there is an increasing need for energy. Fossil fuels will continue to dominate the world energy supplies in the 21st century and coal will play a significant role. Since coal is one of the most important fossil fuels in the world, coal gasification technology appears to be an inevitable choice for power and chemicals production and has a leading place in Clean Coal Technology (CCT). The most eminent environmental advantage of coal gasification lies in its inherent reaction features that produce negligible sulfur and nitrogen oxides, as well as other pollutants in a reducing atmosphere. The gasifier was operated for a throughput of 1.0 ton & 10.0ton coal per day at pressures of 1~20Bar. Gasification was conducted in a temperature range of $1,100{\sim}1,450^{\circ}C$.

Since contaminants of syngas obtained from the biomass gasification are removed, the syngas is clean fuel. In this study a high-efficiency energy production system is developed. The system produces electricity using a waste pressure and feeds a low-pressure steam to Dyeing industrial complex. Also, iron oxide derived from dyeing sludge is utilized as a self-catalyst to reform a tar and reduce a tar emission from gasifier. This system increases the amount of syngas and finally achieves a highly efficient gasification.

An ammonia fuel system is developed and applied to both a spark ignition engine and a compression ignition engine to use ammonia as primary fuel in this study. Ammonia is injected separately into the intake manifold in liquid phase while gasoline or diesel is also injected as secondary fuel. As ammonia burns 1/6 time slower than gasoline or diesel, the spark or diesel injection timing is needed to be advanced to have better combustion phasing. The test engine showed quite high variation in the power output with large amount of ammonia. The final goal of the study is to implement a methodology to ignite ammonia-air mixture and have complete combustion without any use of the conventional fuels.

Global energy demand has continued to rise due to population increase and economic development. National governments and international bodies try to seek the ways to reduce the demand growth. Energy Technology Perspectives (ETP) have provided the current status of energy system, technology developments and external events that have changed ETP scenario since 2006. The status and prospects for key energy technologies of transport sector are presented. Technology portfolio for the transport sector should be needed to meet very low CO2 targets. The portfolio includes improved fuel economy of current internal combustion engine vehicles, advanced technologies such as electric and fuel-cell vehicles, advanced biofuels and demand-side management.

Recently, studies on Mild combustion have grown in many combustion application fields in the international combustion society. Compared with international activities in this field, domestic study in Korea has not been activated yet. This brief review aims to explain some essences of fundamental physics of Mild combustion and to introduce some recent application techniques of them. Fundamental physics of Mild combustion has been usually broken down into three aspects [1]; physical, thermodynamic, and chemical aspects. A major portion of Mild combustion physics is related to HiTAC (High Temperature Air Combustion) or HiCOT (High Temperature Combustion Technology). Although definition of Mild combustion is easily accepted among combustion engineers, combustion control in Mild combustion may be difficult without understanding essential physics of it. To encourage the research in this field, some representative cases will be introduced, and related essential techniques will be explained.

Experiments have been performed for the burners used in the non-oxidizing direct fired furnaces for the cold rolled plate to investigate the effect of fuel/air mixing patterns of the burner nozzle on flame shape, temperature and combustion gas concentration. CFD simulation has also been performed to investigate the mixing state of air-fuel for a nozzle mixing burner and a partially pre-mixing burner. A partially pre-mixing burner showed that flame temperature increased up to $26^{\circ}C$ on average compared than that of the nozzle mixing. It also showed that the mixing distance is important at the partially pre-mixing burner. Test results for a partially pre-mixing burner showed that the residual oxygen concentration and the volume ratio of $CO/CO_2$ of the flame were applicable to be used in field furnaces.

In Korea, only butane gas could be used as fuel gas of the outdoor gas stove. However, butane is not vaporized well at low temperatures. For this reason, in the field, nozzle of the portable butane gas stove is converted illegally to use propane gas. Because vapor pressure of propane gas is higher than that of butane gas at same temperature, gas accidents such as gas leakage could be occurred. To prevent gas accidents and use portable propane gas stoves safely, international standards need to be analyzed and verification tests need to be performed with prototype stove. This study could suggest to revise standard for safety improvement with portable propane gas stoves.

Petroleum coke has high heating value and low price. Due to the steadily increasing demand for heavy oil processing, the production volume of petroleum coke tends to be expanded. The high availability and low price of petroleum coke have been strongly considered as candidate fuel for power generation facilities. However the high carbon content, high sulfur content and nitrogen content of petroleum fuel are known to produce relatively large quantity of CO2, high NOx and SO2 emission. In this work, a series of numerical simulations have been carried out in order to investigate the effects of swirl flow intensity on combustion furnace, which is most important operating condition. Results show that the temperature distribution was spatially uniform at about 1600K but high temperature region are located quite differently depending on swirl number. In addition, numerical temperature data was compared with experimental temperature data and its temperature difference shows less than 10%. On the other hand, discrepancy between numerical and experimental emission data were slightly large with necessities of improved emission model.

Flameless combustion, well known as MILD (Moderate Intensity Low oxygen Dilution) combustion or CDC(Colorless Distributed Combustion), is considered as one of the promising technology for achieving low NOx and CO emissions with improving thermal efficiency of combustion system. In this paper, the effects of exhaust gas dilution rate on formation of flameless combustion of liquid fuel were analyzed using three-dimensional numerical simulations for application of gas turbine combustor with high power density. Results show that the local high temperature region was decreased and flame temperature was spatially uniformly distributed due to higher dilution rate of burnt gas as similar pattern of gas phase flameless combustion. But the evaporation and mixing process of liquid fuel are found to be another important factors for formation of flameless combustion.

Pyroprocessing (or pyrometallurgy) is the way of extracting from materials subjected to high temperatures. Generally, this process has a high energy consumption because of mass production and heating-up. To attain effective and efficient energy management, energetic analysis using 0-dimensional model is usually conducted. However, this model can lead to a misunderstanding about energy evaluation due to many assumptions and limitations. In this study, heat & mass balance using 0-dimensional model was reviewed to systematize problems and considerations in general process energy evaluation.

Commercial gas burning appliances are classified by KGS AB338. Even though there are many types of gas appliances with different purposes and uses, common standards are applied to the appliances. Manifold of commercial gas range could often be corroded by salt water. Gas leaks and accidents could be occurred by the corrosion. According to suggestion of detailed material standards for manifold of commercial gas range, it could help to use safely and prevent gas accidents.

High pressure combustion with multiphase--liquid, gas, and supercritical phase--mixtures are widely used technology in the high efficiency liquid propellent rocket engine. This is the typical characteristics differentiate from the combustor of conventional air-breathing engines. Therefore, successful research of high pressure combustion at supercritical condition is essential to develope a high efficiency liquid rocket engine. Numerical studies have been carried out to explore capabilities of numerical method for LOx-CH4 non-premixed flames at high pressure. In this paper, corresponding numerical results are presented and compared with experimental result of MASCOTTE facility.

Combustion gases emit various radiation signals by chemical reaction and excited molecules in combustion system. Since temperature measurement of combustion system is very difficult, non-contact temperature measuring methods are being researched. In this paper, we propose optical system of simple structure and implement technique for measuring temperature partially in furnace using radiation wavelength signals of high temperature $CO_2$ gas generated during combustion.

The structure performance of a sealed power facilities and the explosion simulation contains significant amounts of scatter, and variability has been characterized in material properties of the structure, a sealed space density, combustible gas volume, gas concentrativeness, ignition site, and gas volume. In order to deal with such uncertainties, structural reliability analysis calculates the failure probability and the reliability index relevant to selected limit states providing quantitative measures of these uncertainties. In this study, structure safety assessment method on the explosion of a sealed power facilities was proposed by using the response surface method (RSM).

The homogeneity and the long term stability for HCNG(CNG composed of about 20 % hydrogen) have been studied. The homogeneity by using ANOVA shows that the HCNG mixing gas is homogeneous ; the relative uncertainty of homogeneity is 0.0375 %. The long term stability for HCNG mixing gas by using F-test and t-test shows that HCNG mixing gas is stable ; the relative uncertainty of the long term stability is 0.0682 % for seven months.

Underground power plant is required the strict safety management and safety assessment. Because it is the high risk of explosion by characteristic of enclosed space. In case gas leak of enclosed space, the ventilation facilities is very important in order to prevent explosion by the maintain less than the LEL(lower explosive limit). Thus, Through a safety assessment of ventilation volume is to reduce the risk for ventilation facilities in Underground power plant.

As the user demand for power plants becomes various, design objective becomes complicated. To review the system feasibility, system objective and evaluation criteria need to be newly defined. In this study, engineering design procedure of the multi-purpose power plant, such as barge-mounted combined cycle power plant with $CO_2$ capture, was shown as a previous work for the feasibility review of the system alternatives. For the system design, heat and mass balance for each system configuration was firstly performed. Using the thermal analysis results, conceptual design of system alternatives was carried out. And then, preliminary design of the major equipment was done. The engineering calculation results of this study would be used as the evaluation data for system feasibility review.

In this study, a method of using a capacitance sensor was investigated as a means to measure the mass fraction of a type of harmful substance. Using MEMS process, we developed a capacitance sensor and studied the real time mass fraction with harmful substance mixture liquid.

Rotary kiln produces lime from limestone through thermal decomposition. Ring formation in kiln internal wall is known issue that decreases productivity. The cause of ring formation is temperature imbalance as flame leans toward upper wall. Therefore, burner nozzle geometry was changed to improve air-fuel mixing state which leads to prevention of ring formation. CFD simulation and experimental test were performed in this study to investigate the effect of air-fuel mixing on flame structure, temperature and $NO_X$ concentration. It is shown that combustion efficiency has been enhanced and $NO_X$ concentration has been decreased by using swirl flow for secondary combustion air. It's also shown that flame has been straightened by using straight flow for secondary combustion air.

Ethanol as fuel of Spark Ignition Direct Injection (SIDI) engine has become a feasible alternative due to its better anti-knock characteristics and lower nano-particle emission level. There are a number of studies on the emission characteristics from SIDI engine fuelled with various ethanol contents. In general, increase of ethanol contents leaded to decrease of nano-particle discharge, but the other researches showed reversed result at a singular range of ethanol contents. This study focused on the engine combustion performance and nano-particle emission characteristics of SIDI engine fuelled with intermediate ethanol contents.

After-treatment system for gasoline direct injection engines should be considered due to the regulation standard for particle number emitted from spark ignition engine vehicles. A metal foam particulate filter, which is thought to be more proper for gasoline engines for its unique filtration and heat resistance characteristics, has been evaluated via engine dynamometer tests.

Catalytic steam reforming of tar produced from biomass gasification was conducted using several Ni-based catalysts. K and Mn were used as a promoter over $Ni/Ru/Al_2O_3$ catalyst. The pellet and monolith type catalysts were prepared and applied to lab and bench-scale biomass gasification system. The $Ni/Ru-K/Al_2O_3$ catalyst shown higher performance than $Ni/Ru-Mn/Al_2O_3$ catalyst at low temperature range.

Coherent anti-Stokes Raman spectroscopy is one of the best tools to measure temperature distributions in the flame. Since it does not disturb the flow field, it could be used to study anchoring mechanism especially in the lifted flame. However, the length of probe volume is, normally, much greater than flame thickness. This weak point was overcome with lens combination in this study. It was found out that no peculiar temperature changes was happened near tribrachial point and heat transfer to the upstream was minimal near the flame anchoring position.

An experimental study on effect of AC electric field on upwardly spreading flame over electrical wire, which is insulated by Polyethylene(PE), was conducted. The result showed that upwardly spreading flame leaned toward unburned side with angle of inclination. With applied electric field, size of upwardly spreading flame increased significantly. Flame spread rate showed various trends with inclination, applied voltage and frequency.

A study on laminar coflow jet flames diluted with helium and nitrogen has been conducted to investigate self-excitations. The stability map was provided with a function of nozzle exit velocity and fuel mole fractions of propane or methane. The results show that there exist three types of self-excitations; (1) buoyancy-driven self-excitation (BDSE), (2) Lewis number induced self-excitation coupled with buoyancy (LCB) and (3) Lewis number induced self-excitation (LISE).

In this study, we carried out torrefaction experiment using PKS(Palm Kernel Shell), and Bagasse as a raw material of oversee of herbaceous biomass and using waste wood and logging residue as a raw material of domestic of woody biomass. And then, by analyzing the physical & chemical properties, we investigated the characteristics as a fuel. By using the result of thermo gravimetric analysis, the biomass residue was torrefied for 30 minutes at a temperature range of $250-350^{\circ}C$ in anaerobic condition. As a result, torrefied materials of moisture content are lower than raw, but of fixed carbon, calorific value and ash are higher than raw.

Influence of fuel concentration gradient was investigated near flame extinction limit in buoyancy-suppressed non-premixed counterflow flame with triple co-flow burner. The use of He curtain flow produced a microgravity level of $10^{-2}-10^{-3}g$ in He-diluted non-premixed counter triple co-flow flame experiments. Flame stability map was presented based on flame extinction and oscillation near extinction limit. The stability map via critical diluent mole fraction with global strain rate was represented by varying outer and inner He-diluted mole fractions. The flame extinction modes could be classified into five: an extinction through the shrinkage of the outmost edge flame forward the flame center with and without self-excitation, respectively ((I) and (II)), an extinction via the rapid expansion of a flame hole while the outmost edge flame is stationary (III), both the outermost and the center edge flames oscillate, and then a donut shaped flame is formed or the flame is entirely extinguished (IV), a shrinkage of the outermost edge flame without self-excitation followed by shrinking or sustain the inner flame (V).

The characteristics of gas free jet flows in laminar with having applied electric fields have been investigated experimentally. A single electrode configuration was adopted such that electric fields were applied directly to nozzle and thus the surrounding could be an infinite ground. The experimental results showed that breakdown point at laminar flow has been measured by varying the applied voltage and frequency of AC. The effect of applying electric fields to free jet flow in laminar was discussed in detail.

Laminar lifted methane jet flame diluted with nitrogen and helium in co-flow air has been investigated experimentally. This paper examines the role of chemistry, intermediate species responsible for stabilization of lifted flame. To elucidate the stabilization mechanism in lifted methane jet flames with Sc<1, the chemiluminescence intensities of $CH^*$ and $OH^*$ were measured using ICCD camera at various nozzle exit velocities and fuel mole fractions. It has been observed that the $OH^*$ species can play an important role in stabilization of lifted methane jet flame as they are good indicators of heat release rate which can affect on flame speed and increase stability through reduction in ignition delay time.