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In this study, alternative lignocellulosic biorefineries annexed to a typical sugarcane mill were investigated, to produce ethanol, lactic acid or methanol, or co-production of ethanol and lactic acid, all with surplus electricity for sale by conversion of sugarcane bagasse and harvesting residues (brown leaves) as accessible feedstock. In order to meet the energy demand of the sugar mill and biorefinery, burning a portion of feedstock or fossil source (coal) along with residues in the centralized combined heat and power unit were assumed as energy supplement strategies. A thorough Aspen Plus simulation was developed for each biorefinery scenario considering all required process units and supplementary units (i.e. combined heat and power, waste water treatment and evaporation). Furthermore, mass and energy balances along with costing data were applied to carry out techno-economic analysis, Monte Carlo finical risk study and life cycle assessment, in a multi-criteria desirability matrix. The lactic acid production biorefinery was found to be the most energy intensive process with highest chemical consumption and the highest conversion of biomass carbon input to products. Consumption of coal as an alternative source of energy enhanced the available biomass for valorization. Biorefineries with coal combustion producing ethanol or ethanol-lactic acid showed better environmental performance than methanol producing biorefineries, based on 1 ton of product. Although, the co-production of ethanol and lactic acid showed the largest likelihood of economic success, Methanol producing scenarios had a zero likelihood of an economic viability without substantial financial incentives or enhanced market prices. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to monitor the dynamic cross-sectional behavior of swirling flames using the tunable diode laser absorption spectroscopy (TDLAS) tomographic system. The newly developed online and highly spatially resolved imaging system based on TDLAS tomography was employed to monitor and reveal directly the reaction process in the swirling flame by reconstructing the 2-D distributions of temperature and H2O concentration over a cross section of the flame. The system was demonstrated to be capable of capturing the temperature distribution accurately and inferring the thermal expansion over the cross section of interest in the swirling flame generated by a model swirl injector operating in partially premixed combustion mode. As the equivalence ratio was decreased, thermal oscillations extracted from the real-time 2-D reconstructions were used to infer the instability of the swirling flame. Furthermore, the developed system was applied to capture dynamically the process of blowout of the swirling flame, illustrating that the system can provide firsthand and reliable visual data to help prevent the flame from lean blowout (LBO). This paper reports the first experimental observation of the dynamic cross-sectional behavior of the swirling flame, enabled by the high spatial and temporal resolutions provided by the TDLAS tomographic imaging system. The developed system can help better understand the LBO mechanism so as to improve the performance of low-emission gas turbine combustors. [ABSTRACT FROM AUTHOR]

The aerosols from CO2-depleted flue gas at the National Carbon Capture Center (NCCC) Pilot Solvent Test Unit (PSTU) and Slipstream Solvent Test Unit (SSTU) were measured in real-time using a DEKATI Electric Low Pressure Impactor (ELPI+TM). The coal-fired flue gas is provided by Alabama Power's Gaston Power Plant Unit 5. The utilization of ELPI+TM for aerosol research in postcombustion CO2 capture is very important due to its quick response time with size classification as low as 6 nm under transient conditions observed at the NCCC. Different process changes have been quantified at the PSTU and SSTU by multiple tests using the ELPI+TM. The performance of smooth and sintered collection plates during dynamic process changes has been investigated. Between separate tests, upstream at unit 5, a new baghouse was installed. The aerosols measured at SSTU, before and after the baghouse installation, are compared. PSTU measurements demonstrated sample sensitivity to transient intercooler start-up conditions and dilution gas temperatures. During the tests, the typical concentration ranged from 106 to 107 cm-3. The aerosol's counter median diameter (CMD) for the sintered plates are lower (47-60 nm) compared to the normal plates (89-130 nm). The optical images indicate that sintered plates soak up all of the collected aerosols. The aerosol number concentration showed a significant drop after the baghouse installation. These results are promising and will enable the development of process control strategies to mitigate solvent losses and reduce operation and maintenance expenses. [ABSTRACT FROM AUTHOR]

Photodynamic therapy has emerged as an alternative treatment for cutaneous leishmaniasis, and compounds with photocatalytic behavior are promising candidates to develop new therapeutic strategies for the treatment of this parasitic disease. Titanium dioxide TiO 2 is a semiconductor ceramic material that shows excellent photocatalytic and antimicrobial activity under Ultraviolet irradiation. Due to the harmful effects of UV radiation, many efforts have been made in order to enhance both photocatalytic and antimicrobial properties of TiO 2 in the visible region of the spectrum by doping or through modifications in the route of synthesis. Herein, Fe-, Zn-, or Pt- doped TiO 2 nanostructures were synthesized by solution-combustion route. The obtained compounds presented aggregates of 100 nm, formed by particles smaller than 20 nm. Doping compounds shift the absorption spectrum towards the visible region, allowing production of reactive oxygen species in the presence of oxygen and molecular water when the system is irradiated in the visible spectrum. The Pt (EC 50  = 18.2 ± 0.8 μg/mL) and Zn (EC 50  = 16.4 ± 0.3 μg/mL) –doped TiO 2 presented the higher antileishmanial activities under visible irradiation and their application as photosensitizers in photodynamic therapy (PDT) strategies for the treatment of cutaneous leishmaniasis should be considered. [ABSTRACT FROM AUTHOR]

Zhundong coal (ZDc) with a very large reserve is faced with severe problems of slagging and fouling during combustion in boilers because of the high-Na content. Sludge, the by-product of urban sewage treatment, is also faced with the problem in utilization. In this study, the co-combustion of ZDc and sludge was investigated in a laboratory-scale experimental apparatus before further studies in larger-scale setups. The experimental results confirm an interaction between ZDc and sludge during co-combustion, which was mainly caused by the Na catalytic action and improved the combustion performance of the co-fuels. The catalytic effect was particularly significant at low sludge mixing ratios. The reactions between Na-based compounds in ZDc and Si/Al/P-rich minerals in sludge, forming high-melting-point phosphates and aluminosilicates, not only increased Na retention in residual ash reducing the risk of fouling on tail-heating surfaces in boilers, but also raised the ash fusibility of the co-fuels avoiding low-temperature sintering. Even so, to prevent slagging, the high combustion temperature above 900 °C should be avoided during co-combustion because of the high Na retention in residual ash. Moreover, the high heavy metal retention in residual ash decreased the pollution caused by heavy metal volatilization during sludge combustion. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effects of HE20 hydrous ethanol gasoline (20% hydrous ethanol v/v) on the cycle-to-cycle variation in a spark ignition engine. Comparative experiments were carried out on a port fuel injection engine fueled with HE20, anhydrous ethanol gasoline (E20) and pure gasoline (E0). The engine was run at speeds of 1200 rpm, 1600 rpm, and 2000 rpm and the engine loads were varied from 10 Nm to 50 Nm for each speed, because higher cyclic variation occurs at relatively low engine load. Our experimental results show that the influence of HE20 on cyclic variation depends on the engine working conditions. At low speeds and low loads, the combustion variation of both E20 andHE20 is reduced in contrast to the results with gasoline. However, utilization of HE20 still has higher cycle-to-cycle variation than E20. At 1600 rpm, HE20 performs poorer and its cyclic variation is higher than the other fuels. At 2000 rpm, the addition of hydrous ethanol promotes the combustion process and the cycle-to-cycle variation of HE20 is lower than that of E20 and E0. From the correlation coefficient of combustion phase related parameters conclusions are gained that the variation of first half stage of combustion is affected by the flame development period whereas the after burning also plays an important role in increasing the cyclic variation. [ABSTRACT FROM AUTHOR]

In this paper, an experimental study was carried out to assess the effects of diesel/ethanol blends, including pure diesel, diesel (90%)/ethanol (10%) (E10, by mass) and diesel (80%)/ethanol (20%) (E20), on combustion and exhaust particulate matter emissions characteristics in a four-cylinder Diesel engine under a low engine load condition with different injection timings and exhaust gas recirculation ratios. Results indicated that ethanol addition delayed the ignition timing and shortened the combustion duration, meanwhile, produced higher brake thermal efficiency and lower brake specific fuel consumption. Moreover, the total particulate and nucleation mode particle (particle size Dp < 50 nm) number concentrations were increased and the total particulate mass and the accumulation mode (50 nm < Dp < 1000 nm) number concentration were decreased when engine fueled with diesel/ethanol blends compared to pure diesel. [ABSTRACT FROM AUTHOR]

Compared with pure Diesel fuel, Diesel engine fueled with 2,5-dimethylfuran/diesel prolonged the ignition delay, shortened the combustion duration, increased the engine efficiency and decreased the number of accumulation mode particles (50 nm < Dp < 1000 nm), but increased the nucleation mode (Dp < 50 nm) number. The mean diameter of particles was declined with 2,5-dimethylfuran addition due to the increase of small particles number. Ethanol/diesel was more effective in extending the ignition delay, shortening the combustion duration, enhancing the engine efficiency and reducing the number of large size particles, but produced more small size particles compared with 2,5-dimethylfuran/diesel. [ABSTRACT FROM AUTHOR]

The paper presents results of experimental investigation of co-combustion of fuels of various reactivity at dual fuel Diesel engine. The tested fuels were ethanol fuel (EF) and diesel. It was used one-cylinder direct injection Diesel engine. Researches were conducted at constant rotational speed and constant injection timing. With the increase in EF fraction the deterioration of combustion process was indicated. On the basis of heat release variation were determined combustion phases: ignition delay, combustion duration. With the increase in EF participation in combustion processes the IMEP increased as well. There was no noticeable effect of ethanol on unrepeatability of indicated mean effective pressure. The increase in EF fraction causes the specific NOx emission decreases but specific total hydrocarbon emission increased. [ABSTRACT FROM AUTHOR]

In this study, a pre-chamber was designed to form near stoichiometric mixture and provide multiple turbulent flame jets to ignite the lean mixture and accelerate the combustion in the main combustion chamber for a natural gas engine. A CFD simulation was employed to investigate the impact of the pre-chamber nozzle configurations on flow and combustion processes inside the engine, as well as on the performance of the engine. Various configurations were investigated, including orifice number of 4 to 8 and orifice diameter ranging from 1.6 m to 2.9 mm. A non-dimensional parameter, β, was used to characterize the relative flow area of these configurations. The numerical results indicate that, for a given nozzle flow area, among the design of different orifice numbers, the 6-orifice design can obtain the optimal combustion and engine performance. Otherwise, a design of more orifices leads to slower flame penetrating speed in the main-chamber, and the design of less orifices leads to slower circumferential flames propagations in the main-chamber. Moreover, for a 6-orifice pre-chamber, the optimal orifice diameter was found to be 2.0 mm, corresponding to a β value of 0. 3. A design of larger diameters leads to slower penetrating for the flame jets and insufficient radial flame propagations in the main-chamber, while a design of relatively smaller orifice diameters leads to insufficient circumferential flames propagations in the main-chamber. Additionally, for the engine performance, all the pre-chamber designs improve the indicated efficiency and reduce the NOx emission. Especially, the design of 6-orifice with diameter of 2.0 mm achieves a 35.0% increase of indicated thermal efficiency and a 78.0% reduction of NOx emission compared to the prototype engine. [ABSTRACT FROM AUTHOR]

Sonochemically-generated Ti−Al−B reactive mixed-metal nanopowders were tested by seeding them into a premixed, fuel-lean (Φ = 0.63), methane/air flame to investigate their combustion characteristics. Tests were conducted on powders with and without cryogenic milling. The attenuation of a diode laser beam was measured to calculate the time-resolved concentration of the powder in the flame. Radiant heat flux was measured with three gauges at different heights (1 cm, 6 cm, and 12 cm) along the axis of the flame. Flame spectra were collected to monitor chemiluminescence of intermediate species, and a multi-wavelength pyrometry method was applied to the spectra to calculate the temperature of the hot particulates in the flame. Commercially available metal powders were tested as a benchmark. These included micron-scale aluminum, nano-scale aluminum, micron-scale boron, and inert nano-scale alumina powders. The spectra from flames seeded with the sonochemically-generated Ti−Al−B powder show strong chemiluminescence from the BO 2 , an indicator of boron oxidation. Peak temperatures measured with flame pyrometry were approximately 2100 K, which is below the vaporization point of B 2 O 3 . The radiant heat flux from the seeded flame increased with concentration faster for the Ti−Al−B material than for any of the commercial powders, suggesting a greater gravimetric power density. Based on these results, the Ti−Al−B powders show promising combustion and heat-release characteristics, and therefore warrant further examination as a high-performance solid fuel. [ABSTRACT FROM AUTHOR]

This paper introduces a novel post-processing technique for analyzing high dimensional combustion data. In this technique, t-Distributed Stochastic Neighbor Embedding (t-SNE) is used to reduce the dimensionality of the combustion data with no prior knowledge while preserving the similarity of the original data. Multidimensional combustion datasets are from premixed and non-premixed laminar flame simulations and measurements of a series of well documented piloted flames with inhomogeneous inlets. The resulting reduced manifold is visualized by scatter plots to reveal the global and local structure of the data (manual labeling). Unsupervised clustering algorithms are then utilized for post-processing the t-SNE manifold in order to develop an automatic labeling process. [ABSTRACT FROM AUTHOR]

As in any fluidized bed application, the nozzle grid of a CFBC riser has the task of supplying fluidization/primary combustion air to the combustion chamber with a uniform distribution and at the same time retaining the coarse ash to form a dense bed at the riser bottom. A typical issue in large scale CFBs is a maldistribution of primary air caused by either excessive nozzle wear in certain grid regions or clogging and blocking on the other hand. The contribution presents a joint method of grid nozzle measurement and CFB combustion simulation for plant performance assessment. Results of erosion patterns and their effect on primary air maldistribution and subsequent combustion issues for a 105MWth CFBC are shown. The method of nozzle grid field measurements combined with detailed flow and combustion computations provides the CFBC operator with information on required number of nozzles to be changed in order to ensure uniform air distribution and at the nozzle grid. As a prerequisite for burn-out quality, boiler efficiency and emission control, the nozzle grid assessment is an effective measure to reduce boiler maintenance costs. [ABSTRACT FROM AUTHOR]

The paper presents the results of observing, in a real time, the process of combustion in air of aluminum nanopowder ignited by laser radiation. The obtained results convincingly evidence the possibility and perspective of visualization of ignition process by means of laser monitor. The video images allow observing the main stages of the combustion process including starting of combustion in the place of laser radiation focusing, spreading of the heat wave and appearance of the second combustion wave. For quantitative analysis of the combustion process, we suggest to analyze the average intensity of images registered by laser monitor. [ABSTRACT FROM AUTHOR]

This paper examines the effect of igniter type (glow plug vs. spark igniter) and number of igniters on the dynamics of vented combustion under both initially quiescent and fan-induced turbulent conditions. These experiments are a subset of many series of tests performed in a 120 m 3 large scale vented combustion test facility at the Canadian Nuclear Laboratories using near lean flammability hydrogen-air mixtures (8–12% H 2 ). One of the objectives of these studies was to have a better understanding of the effectiveness of deliberate ignition for mitigation of hydrogen during a postulated accident and to provide data for code validation. The test results of the current study show that the two types of ignition sources have no significant influence on the maximum combustion overpressure except that the initial burning rate is slightly faster using the spark igniter. Under either the quiescent or turbulent conditions, the maximum combustion overpressure always increases with an increase in the number of igniters, but under the current experimental conditions, the turbulent combustion overpressure with one igniter is always higher than quiescent combustion with multiple igniters. [ABSTRACT FROM AUTHOR]

Summary: The diethylenetriamine chelate complex of copper(II) carbonate—DETA‐CuCO3 (a fire retardant hardener of epoxy resins)—and the CuCO3‐containing epoxy‐amine polymers—DGEBA/DETA‐CuCO3(6), DGEBA/DETA‐CuCO3(12), DGEBA/DETA‐CuCO3(40), and DGEBA/DETA‐CuCO3(80) with suppressed combustibility—have been obtained in the DETA‐DGEBA‐CuCO3 system (DETA and DGEBA are diethylenetriamine and bisphenol A diglycidyl ether, respectively). The DETA‐CuCO3 chelate complex was characterized by X‐ray powder diffraction, infrared spectra, and thermal analysis. The thermal gravimetric analysis results have revealed that thermal destruction of DETA‐CuCO3 was finished at 400°С, and the maximal temperature of the combustion gases amounted to 520°С. The thermal behavior and combustibility of the CuCO3‐containing epoxy‐amine polymers were studied using thermal analysis and “Ceramic tube” (CT) method. Thermal gravimetric analysis confirms that incorporation of the DETA‐CuCO3 into DGEBA appreciably heightens the thermal stability and antiflammability of the CuCO3‐containing epoxy‐amine polymers. Results of CT measurement reveal that maximal temperature of the combustion gases under burning of the DGEBA/DETA‐CuCO3(12) sample in comparison with unmodified epoxy‐amine polymer (DGEBA/DETA) is lowered on 219°С and the loss of weight is decreased on 20.5 wt%. According to ASTM 635‐14, ASTM D2863‐13, and ASTM D1929‐16, the flame propagation rate, limiting oxygen index, and temperatures of ignition and self‐ignition have been measured for the elaborated polymer samples. [ABSTRACT FROM AUTHOR]

One of the main challenges for wide-spread utilization of the solid oxide fuel cell (SOFC) power systems is how to achieve high electrical efficiency without increasing the degradation rate of the fuel cells. To run the SOFC power system at high efficiency over a long period of time, properly designed controllers are indispensable. Although a number of various approaches to control SOFC have been proposed so far, it seems that the design of control system, along with simple tuning procedure, has not been treated in a consistent manner. This issue is addressed in the present paper resulting in a feedforward-feedback control structure. The feedforward part is based on the stoichiometry of electro-oxidation, reforming and combustion reactions, which allow immediate response to variable current demand. The feedback part performs additional fine adjustment of fuel and air supply in order to minimize the undesired system temperatures variations. The selection of pairings of manipulated and controlled variables for control is based on physical knowledge of the system. Input/output pairing for single-loop feedback control is assessed by the relative gain analysis. An efficient procedure for tuning the parameters of the feedback controllers is suggested, relying on simple open-loop step responses of the system. The proposed low-level control is assessed on a detailed physical model of a 2.5 kW SOFC power system by simulating two nonstationary load regimes. Simulations show that the control provides a robust operation under large load variations while meeting the operating constraints. Due to its simplicity, the control is feasible for implementation on a real SOFC system. [ABSTRACT FROM AUTHOR]

With a specific end goal to take care of the worldwide demand for energy, a broad research is done to create alternative and cost effective fuel. The fundamental goal of this examination is to investigate the combustion, performance and emission characteristics of diesel engine using biodiesel blends enriched with HHO gas. The biodiesel blends are gotten by blending KOME obtained from transesterification of karanja oil in various proportions with neat diesel. The HHO gas is produced by the electrolysis of water in the presence of sodium bicarbonate electrolyte. The constant flow of HHO gas accompanied with biodiesel guarantees lessened brake specific fuel consumption by 2.41% at no load and 17.53% at full load with increased the brake thermal efficiency by 2.61% at no load and 21.67% at full load contrasted with neat diesel operation. Noteworthy decline in unburned hydrocarbon, carbon monoxide, carbon-dioxide emissions and particulate matter with the exception of NO x discharge is encountered. The addition of EGR controls this hike in NO x with a slight decline in the performance characteristics. It is clear that the addition of HHO gas with biodiesel blends along with EGR in the test engine improved the overall characterization of engine. [ABSTRACT FROM AUTHOR]

Several alternative synthetic fuels are in discussion as a replacement for conventional fuels like Jet A-1 to cope with limited supplies of crude oil as well as their emissions connected with its use such as the greenhouse gas CO 2 . One of the alternative fuels which have received high attention recently is farnesane (2,6,10-trimethyldodecane), a biofuel produced from sugar using a biotechnological process. In this paper, combustion characteristics of farnesane were investigated by measuring its ignition delay time using a shock tube at elevated pressure (16 bar) and two different stoichiometries ( φ  = 1.0 and φ  = 2.0) and the laminar burning velocity at atmospheric and elevated pressures (1, 3, and 6 bar). These results were compared to a conventional Jet A-1 fuel showing that farnesane has a similar combustion behavior. Furthermore, a reaction model was developed capable to predict the measured combustion properties. The calculation of the ignition delay times yields excellent results when compared to the measurements; the computations of the laminar flame speeds are in good agreement with the measurements. In addition, the reaction model was analyzed to get further insight into the main reaction steps of farnesane oxidation. [ABSTRACT FROM AUTHOR]

Nanocrystalline Ni x Zn 1-x Dy y Fe 2-y O 4 (x ≤ 0 ≤ 1.0; y = 0.0, 0.1) ferrites were prepared by solution combustion method. Structural investigation was studied using XRD, FTIR, SEM and EDAX techniques. All samples were irradiated with 60 Co gamma source with total exposure dose of 310 kGy. XRD patterns revealed the formation of cubic spinel structure. FTIR spectra confirm the presence of two prominent vibrational bands. DC conductivity was found to obey the Arrhenius relation with a change in slope at Curie temperature and impedes with Dy 3+ ion content. ZnFe 2 O 4 nanoparticles exhibit a weak ferrimagnetic behavior at 300 K. The saturation magnetization, remanence magnetization, coercivity, remanence ratio, magneton number and Yaffet–Kittle angle were found to decrease in Dy 3+ ion substituted samples attributed to redistribution of cations amongst the sites and weakening the A-B exchange interactions. The enhancement of DC conductivity and magnetic parameters on γ-irradiation attributed to surface states pinning of domains released. [ABSTRACT FROM AUTHOR]

This work proposes a novel method of temperature prediction during heavy oil in-situ combustion according to the fuel availability (FA) of true boiling point fractions, which is also called pseudo-components. Six kinds of n -alkanes with different carbon number and three crude oil samples from Karamay oil field were used and each oil sample was chosen to get seven true boiling point (TBP) fractions respectively. Kinetic cell experiment with ramped temperature oxidation (RTO) was conducted on each n -alkane and pseudo-component to get the total mole amount of CO and CO 2 . Combustion tube (CT) experiment was performed to obtain the deviation between the calculated value and measured result, which can be used to validate the accuracy of the new method. The results revealed that the FA of n -alkanes presented linear relationship to the carbon number and the average carbon number for different pseudo-components as well as heavy crude oil could be figured out based on this standard curve. Then the reaction heat for pseudo-components and the whole oil could be calculated and used to predict the temperature of fire front in CT experiment. There is a deviation below 50 °C between the calculation and the thermocouples measurement during the CT experiment, which can be acceptable in reservoir temperature prediction. [ABSTRACT FROM AUTHOR]

In the present work, the formation mechanism of high-intensity combustion with high pressure oscillation and its destructive effects was studied by a newly designed constant volume combustion bomb equipped with a perforated plate. The stoichiometric H 2 -air mixture was selected as the test fuel because of its high flame propagation velocity with obvious shock wave, which easily leads to a strong pressure oscillation. Two kinds of high-intensity combustion phenomena, including the continuous acceleration of the flame front and end-gas auto ignition, were obtained. The results show that the ultrafast and intense combustion would lead to a high pressure oscillation, consequently caused damage to the experimental device, such as the optical glass and perforated plate. The perforated plate vibrated back and forth in situ forced by the combustion waves. The peak pressure was up to 10.3 MPa and maximum amplitude of pressure oscillation was 4.2 MPa when the optical glass was damaged. And according to FFT analysis, the frequency of in-cylinder pressure changed because of the combustion mode transition. The present work provides an alternative method to not only grasp the destructive mechanism of knocking combustion, but also understand the destructive effect of the combustion of the hydrogen-air mixture. [ABSTRACT FROM AUTHOR]

Self-propagating high-temperature synthesis as a low energy consumption and simple approach was employed to synthesise silicon nanocrystal from the monolithic silica cryogel prepared by freeze drying. The recrystallisation process of silicon was investigated under combustion at 800, 900 and 1000°C and the uniform coral-like structure was achieved at 1000°C. The results of Raman and X-ray diffraction analysis showed the decrease in ignition time to 40 s for 1000°C temperature, leading to the decrement of crystalline size to 10.85 A° and the raise of average lattice strain to 0.152% due to accelerating recrystallisation. In addition, NaCl diluent consumed the excess heat generated during exothermic reaction and decreased the crystalline size to 10.79 A° thanks to its 0.8 W/m K thermal conductivity. [ABSTRACT FROM AUTHOR]

This paper reports on the results of air-blown combustion and oxy-combustion kinetic characterization (comparing two different isoconversional methods: Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose) of different kinds of coal (from Italy, South Africa and Hungary) and biomass (pine and eucalyptus chips) by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) together with the assessment of different characteristic combustion parameters. It can be observed that the burning rate of fuels can be improved by the oxy-combustion process, shortening the burning time (a mean reduction of the burnout time of 14% and 22% can be observed for coal and biomass samples, respectively). Moreover, biomass shows better ignition performance than coal and enhances combustibility indexes ( S and H f ), especially in oxy-combustion conditions. For example, the S index, which reflects combustion properties, increases by an order of magnitude for biomass combustion and oxy-combustion with respect to coal values, thus indicating a higher combustion activity for biomass; an opposite trend can be observed for the H f index, which describes the rate and intensity of the process and is lower for biomass than for coal, thus indicating better performance for wood chips combustion. Kinetic analysis shows that the activation energy E a varies with conversion values, reflecting the kinetic complexity in both the processes. Moreover, with the same range of heating rates (10 ≤  β  ≤ 50 °C/min) and for the overall range of conversion (0.1 ≤  α  ≤ 0.9), both of the models used fit the experimental data in combustion regime, whereas the increase of the oxygen concentration makes the results reliable for coal samples and more sensitive to weight loss for biomass samples. [ABSTRACT FROM AUTHOR]

Experiments are carried out to investigate the effects of dome structure on the combustion performance of a trapped vortex combustor. The effects are directly explored in terms of combustion efficiency, ignition and lean blowout limits with three different dome structures. The experimental results indicate that the fairing-tube configuration exhibits excellent advantages in lean blowout limits and the outer-cavity ignition performance, whereas the fairing-plate configuration performs rather poorly. Interestingly, the fairing-plate configuration shows prominent superiority in the ignition performance of the inner-cavity. Additionally, the basic configuration performs moderately both in ignition and lean blowout limits. For the combustion efficiency, the fairing-plate configuration achieves the highest combustion efficiency when only cavity is fueled. Both expected and unexpected results are found when cavity and mainstream are fueled simultaneously. As anticipated, higher combustion efficiency are achieved by the basic configuration and fairing-plate configuration at low fuel/air ratio conditions. However, the highest combustion efficiency is obtained by the fairing-tube configuration at high fuel/air ratio conditions. Numerical simulations of non-reacting flows are then conducted to explain the experimental results. The great discrepancies in combustion characteristics may mainly attribute to the significant differences of the flow patterns both in cavity and mainstream. [ABSTRACT FROM AUTHOR]

An enhanced flexible dynamic model for a valve train with clearance and multi-directional deformations is proposed based on finite element method (FEM), and verified by experiment. According to the measured cam profile, the available internal excitations in numerical solution to the model are achieved by using piecewise cubic Hermite interpolating polynomial. The comparative analysis demonstrates that the bending deformation of the rocker arm is much larger than the radial deformation, signifying the necessities of multi-directional deformations in dynamic analysis for the valve train. The effects of valve clearance and cam rotation speed on contact force, acceleration and dynamic transmission error (DTE) are investigated. Both theoretical predictions and experimental measurements show that the amplitudes and fluctuations of contact force, acceleration and DTE become larger, when the valve clearance or cam speed increases. It is found that including the elasticity and the damping will weaken the impact between the rocker arm and the valve on the components (not adjacent to the valve) at either unseating or seating scenario. Additionally, as valve clearance or cam rotation speed becomes larger, the valve lift and the working phase decrease, which eventually leads to inlet air reduction. Furthermore, our study shows that the combustion rate improvement, input torque, and components durability can be improved by tuning valve clearance or adjustment the cam profile. [ABSTRACT FROM AUTHOR]

This work presents numerical results for two-dimensional combustion of an air/methane mixture in inert porous media using a macroscopic turbulence model. Conservation equations for mass, momentum, energy and chemical species are obtained based on volume-and-time double averaging concept. Distinct energy balances are considered for the porous burner and the gas mixture. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure–velocity coupling. Effects of inlet mass flow rate, excess air, porosity and thermal conductivity ratio, on both the preheating section and combustion region, were investigated. Increasing the mass flow increases peak gas temperatures and pushes the flame front from the preheating zone towards the burner exit. Stoichiometric mixture provokes undesirable combustion in the preheating zone while lean mixtures lower temperatures and pushes flame front forward. Low porosity in the preheating zone promotes more conduction of heat in that region whereas low ϕ values in the combustion zone raises gas and solid temperatures everywhere in that zone. [ABSTRACT FROM AUTHOR]

A parametric study on some combustion characteristics was carried out in a natural gas fueled dual plugs SI engine. Mass fraction burned, cylinder pressure histories and combustion durations of the engine were investigated by three equivalence ratio and spark advance for three spark plug configurations. It was found that equivalence ratio and spark plug configurations were more effective parameters on the total combustion duration than spark timing and was concluded that centrally located single plug configuration for equivalence ratio of 1.0 gives best combustion characteristics in compared to the other conditions. In addition, presented study showed that dual plugs serve an alternative for fast combustion in case of geometric constraints to use central location of the plug. [ABSTRACT FROM AUTHOR]

With the development of modified asphalt waterproofing membrane in China, an exhaust gas purification system was introduced in this paper which had been applied in a waterproofing material company in Hangzhou city of China. In allusion to the shortcomings of current purification methods, a new optimization scheme: high-temperature combustion＋heat recovery＋spray was designed. After optimization, it not only reduced the number of equipment, simplified the management, but also achieved remarkable purification effect. Experimental results showed that the total running costs of the optimized system could be reduced by 837,300 yuan per year, of which the heat recovery system of high-temperature exhaust gas could save natural gas about 95,000 m 3 and costs about 265,050 yuan. [ABSTRACT FROM AUTHOR]

The char temperature during combustion in a fluidized bed (FB) is often measured by thermocouples due to simplicity, and because it is assumed that the thermocouple effect on the movement of the char is negligible. It is also accepted that the combustion temperature of a char particle fluidized with an embedded thermocouple is similar to a freely fluidized particle. However, few publications have given evidence of this fact. In the present article this question is dealt with by comparing the evolution of conversion and temperature of fluidized char particles with and without an embedded thermocouple. Char from beech wood, sub-bituminous and bituminous coal of an initial diameter of 10 mm is burnt in two laboratory FBs; one 2-dimensional made of quartz with rectangular cross-section allowing visual observation and temperature tracking of the particles, and the other being 3-dimensional with 50 mm internal diameter. The surface temperature of the char particles is followed by a recently developed visual technique, based on pyrometry coupled with a digital camera. The consumption of char is evaluated by sampling particles from the bed at different stages of conversion, analyzing the density and size of the particle. It is found that, due to the greater resistance of the particle-thermocouple to the drag of the bed, the time that the char particle is in the bubble phase is 40% longer when the thermocouple is used, leading to higher combustion rate and temperature, and consequently, shorter burnout time. Moreover, the rotation of the char particle is restricted, provoking a non-homogeneous consumption of char, which enhances the size reduction of the particle along the direction perpendicular to the insertion of the thermocouple. Overall, these findings suggest that conclusions about char conversion by temperature measurements using thermocouples should be made with caution, since significant error might be committed under some operating conditions. [ABSTRACT FROM AUTHOR]

A phenomenological explanation about the autoignition propagation under HCCI conditions is developed in this paper. To do so, diffusive effects from the burned zones to the fresh mixture, pressure waves based effects and expansion effects caused by combustion are taken into account. Additionally, different Damköhler numbers have been defined and evaluated in order to characterize the phenomenon and quantify the relevance of each effect. The theoretical explanation has been evaluated by means of chemiluminescence measurements performed in a Rapid Compression Expansion Machine (RCEM), which allow to estimate the velocity of propagation of the autoignition front. The results showed that under HCCI conditions the autoignition propagation is controlled, in general, by the pressure waves established in the combustion chamber, since the characteristic time of the autoignition propagation is too short to assume the absence of pressure gradients in the chamber. Thus, the thermodynamic conditions reached behind the pressure wave promote the autoignition and explain the high propagation velocities associated to the reaction front. Besides, the results also showed that the contribution of diffusive phenomena on the propagation is negligible, since the characteristic time of diffusion is too long compared to the characteristic time of the autoignition propagation. Finally, the experimental measurements showed that the autoignition propagation is affected by a really relevant cycle-to-cycle variation. The turbulence generated by the combustion has, by definition, an aleatory behavior, leading to random heterogeneity distribution and, therefore, to somewhat random autoignition propagation. [ABSTRACT FROM AUTHOR]

In-situ combustion (ISC) is an oil recovery technique where many phenomena can take place simultaneously such as: chemical reactions, phase change, heat transfer, mass transport, thermodynamic equilibrium, and so on. Each one of these phenomena may have important contributions over the ISC behavior at any scale of interest as lab-scale, inter-wells or reservoir-scale. In this work, a mass transport study is presented. Firstly, the appropriate phase and interface governing equations at pore-scale are set up. Later, the volume averaged equations valid at macroscale are rigorously derived using the volume averaging method (VAM). The theoretical analysis is general and applies for typical oil-water-gas-rock systems found in petroleum reservoirs, and for any number of chemical species distributed in the phases. The model also allows the existence of several heterogeneous and homogeneous chemical reactions. From this general point of view, the volume averaged equations governing species and phase mass transport at macroscale, along its closure scheme to predict the effective transport parameters, are presented. We have clearly identified the length scale constraints and assumptions that support our derivations. In future works, we shall expand the range of applicability of the model by relaxing some of these assumptions. To demonstrate the applicability of the average models, we numerically predicted the longitudinal mass dispersion of oxygen for passive and reactive mass transport problems at lab-scale. The general trends of theoretical results are in concordance with previous works. [ABSTRACT FROM AUTHOR]

The paper presents an option how to acquire simplified input data for modelling of burning wood in CFD programmes. The option lies in combination of data from small- and molecular-scale experiments in order to describe the material as a one-reaction material property. Such virtual material would spread fire, develop the fire according to surrounding environment and it could be extinguished without using complex reaction molecular description. Series of experiments including elemental analysis, thermogravimetric analysis and difference thermal analysis, and combustion analysis were performed. Then the FDS model of burning pine wood in a cone calorimeter was built. In the model where those values were used. The model was validated to HRR (Heat Release Rate) from the real cone calorimeter experiment. The results show that for the purpose of CFD modelling the effective heat of combustion, which is one of the basic material property for fire modelling affecting the total intensity of burning, should be used. Using the net heat of combustion in the model leads to higher values of HRR in comparison to the real experiment data. Considering all the results shown in this paper, it was shown that it is possible to simulate burning of wood using the extrapolated data obtained in small-size experiments. [ABSTRACT FROM AUTHOR]

• The simulation of ultraviolet band absorption spectrum of the typical gaseous products of coal combustion were carried out. • The cross interference effects of combustion gaseous products were analyzed in detail. • The inversion algorithm of H 2 S gas concentration under the background interference of combustion gaseous products SO 2 was put forward. • The sampling, pre-treatment and H 2 S gas concentration measurement system was developed and applied to measure H 2 S concentration of flue gas near the wall in boiler. Measurement of hydrogen sulfide (H 2 S) in gaseous product can provide direct reference for high-temperature corrosion of industrial combustion equipment. Aiming at the interference effect of overlapping measurement of absorption spectrum for H 2 S and other combustion gas components in UV absorption spectroscopy, the simulation calculation of ultraviolet band absorption spectrum of the typical gaseous products of coal combustion were carried out. The cross interference effects of combustion gaseous products were analyzed in detail. Due to the SO 2 and H 2 S gas under typical combustion condition have equivalent absorption strength in the 228 nm-233 nm band, the influence of SO 2 on H 2 S concentration inversion must be emphatically considered, and the inversion algorithm of H 2 S gas concentration under the background interference of combustion gaseous products SO 2 was put forward. In order to validate the measurement accuracy by the inversion algorithm, the measurement experiments of gas mixture of H 2 S and SO 2 were carried out. The results show that the algorithm can effectively solve the problem of cross interference between the detection of H 2 S and SO 2 in the combustion gaseous products by UV absorption spectroscopy. On this basis, the sampling, pre-treatment and H 2 S gas concentration measurement system for boiler flue gas near the wall was developed and applied to measure H 2 S concentration of flue gas near the wall in a 1000 MW ultra-supercritical coal-fired power generation boiler. The results can provide important references for combustion adjustment and high-temperature corrosion prevention of boiler. [ABSTRACT FROM AUTHOR]

• Eliminating the influence of carrier phase on measurement in the time domain. • An improved simulated annealing algorithm is proposed to obtain the optimal temperature and concentration. • It is the first time to obtain temperature and concentration simultaneously through a single spectral line in laser dispersion spectroscopy. • The anti-noise ability is verified by simulation, and the measurement accuracy and repeatability are verified by experiment. • It provides a new idea (time domain analysis) for the solution of laser dispersion spectroscopy. Quantitative measurement of temperature and concentration is of wide interest in combustion diagnostics. In this paper, simultaneous temperature and water concentration measurements in a combustion flame were realized by using a novel laser dispersion spectrum extraction method immune to carrier phase variation. The laser dispersion phase signal obtained in the frequency domain was converted into the molecular free induction decay (FID) signal in the time domain by inverse Fourier transform. Then the FID signals of the dispersion phase and the carrier phase were separated in the time domain. The optimal temperature and concentration values were efficiently searched by an improved simulated annealing algorithm through the FID signal in the window function. Numerical simulations verified the noise immunity of the proposed method at different noise levels. Experiments were implemented on a methane-air laminar premixed flame, and the results showed that the proposed method performed better in measurement stability and accuracy than laser absorption spectrometry, especially in the presence of incident laser power fluctuations. This method is proven promising in the field of combustion diagnosis. [ABSTRACT FROM AUTHOR]

• A new PVA/MMT/MgB 2 flame retardant fiber system. • A synergistic effect between MgB 2 NSs and MMT NSs. • Excellent flame retardant and mechanical properties. • Only 5 wt% MgB 2 NSS can significantly improve the comprehensive performance of composite fiber. Using delaminated montmorillonite (MMT) nanosheets (NSs) and MgB 2 NSs as crosslinking units and methanol as a coagulation bath, polyvinyl alcohol (PVA)/MMT/MgB 2 composite fibers with excellent mechanical and flame-retardant properties were fabricated via wet spinning, and their flame retardancy was studied via limiting oxygen index (LOI) and microcaloric combustion calorimetry measurements. The delaminated MMT NSs (45 wt%) and MgB 2 NSs (5 wt%) can be uniformly dispersed into PVA. The synergistic effect between the MgB 2 NSs and the MMT NSs as well as the formation of a dense char layer with a continuous crosslinked network significantly enhance the mechanical properties and flame retardancy of the PVA/MMT/MgB 2 -5 composite fibers. The fibers possess not only a high mechanical strength of 304 MPa and an elongation at break of 9.8% but also an LOI value of 49.8% and a self-extinguishing time of only 1.2 s for a single fiber. Furthermore, the peak heat release rate and the total heat release are 89% and 85% lower than those of the pure PVA fibers, respectively. PVA/MMT/MgB 2 -5 composite fibers are promising candidates for application in the textile, architecture, and fire protection fields due to their outstanding flame retardancy, high mechanical strength, and good flexibility. [ABSTRACT FROM AUTHOR]

A method and application of measuring the soot volume fraction, H2O concentration, and its temperature simultaneously in an ethylene/air premixed flame environment based on tunable diode laser absorption spectroscopy technique is presented in this article. Only one distributed feedback diode laser with a center wavelength at 1397.83 nm combined with a scanned-wavelength direct absorption spectroscopy technique was used during measurements. The attenuation of laser intensity caused by soot extinction and H2O gas absorption after transmitting through the flame region was detected and distinguished, respectively. Soot volume faction was inferred from the light extinction with Rayleigh limit assumption. The absorption signals of two H2O spectral lines were acquired during one scanning, thus both the H2O concentration and its temperature can be retrieved. Measurements have been taken in ethylene/air premixed flat flames on a standard bronze McKenna burner at different cold-gas velocities (5.9 cm/s and 4.4 cm/s) and equivalence ratios (φ= 2.3, 2.1, and 1.9). The gradient tendencies of soot volume fraction, H2O concentration, and temperature along the vertical direction and the variations in different flames were well demonstrated. The results were in good agreement with the values measured using other techniques and studies. The proposed method is proved to be suitable and accurate for measuring oot volume fraction together with gas concentration and temperature. This multipurpose measuring method with high accuracy exhibits great potential in combustion diagnostics and soot study. [ABSTRACT FROM AUTHOR]

Recent results have experimentally demonstrated the feasibility of obtaining 3D (three-dimensional) combustion measurements using tomographic VLIF (volumetric laser-induced fluorescence), specifically of the CH radical, representing the flame surface. To elucidate the fundamental capabilities and limitations of the VLIF technique, this work reports an analysis of its performance in terms of signal level, size of the field of view (FOV) in 3D, and accuracy. Compared to the established PLIF (planar LIF) technique that uses a thin laser sheet to excite the target species in a plane, the VLIF technique uses a thick laser slab to excite the target species in a volume. As a result, the VLIF technique involves more performance metrics compared to PLIF, and the relationship between these metrics is also different from that in the PLIF technique. Therefore, both experimental and computational studies were conducted to analyze the performance metrics of VLIF. First, experiments were conducted on well-controlled flames to examine the relationship among excitation energy, signal level, and FOV in 3D. Second, based on these experimental data, numerical simulations were performed to benchmark the VLIF technique under a range of conditions. These results illustrate the relationship among signal level, 3D FOV, and accuracy and are expected to be valuable for the optimal design of the VLIF technique. [ABSTRACT FROM AUTHOR]

We present joint analyses of satellite-observed combustion products to examine bulk characteristics of combustion in megacities and fire regions. We use retrievals of CO, NO2 and CO2 from NASA/Terra Measurement of Pollution In The Troposphere, NASA/Aura Ozone Monitoring Instrument, and JAXA Greenhouse Gases Observing Satellite to estimate atmospheric enhancements of these co-emitted species based on their spatiotemporal variability (spread, σ) within 14 regions dominated by combustion emissions. We find that patterns in σXCO/σXCO2 and σXCO/σXNO2 are able to distinguish between combustion types across the globe. These patterns show distinct groupings for biomass burning and the developing/developed status of a region that are not well represented in global emissions inventories. We show here that such multi-species analyses can provide constraints on emission inventories, and be useful in monitoring trends and understanding regional-scale combustion [ABSTRACT FROM AUTHOR]

We present joint analyses of satellite-observed combustion products to examine bulk characteristics of combustion in megacities and fire regions. We use retrievals of CO, NO2 and CO2 from NASA/Terra Measurement of Pollution In The Troposphere, NASA/Aura Ozone Monitoring Instrument, and JAXA Greenhouse Gases Observing Satellite to estimate atmospheric enhancements of these co-emitted species based on their spatiotemporal variability (spread, σ) within 14 regions dominated by combustion emissions. We find that patterns in σXCO/σXCO2 and σXCO/σXNO2 are able to distinguish between combustion types across the globe. These patterns show distinct groupings for biomass burning and the developing/developed status of a region that are not well represented in global emissions inventories. We show here that such multi-species analyses can provide constraints on emission inventories, and be useful in monitoring trends and understanding regional-scale combustion [ABSTRACT FROM AUTHOR]

This paper reports the results of thermal, energy, exergy and economic analysis involving a hard coal fired power plant with a two-column cryogenic oxygen unit and operating in an oxy combustion process. As a novelty it was assumed that the auxiliary steam turbine drives the oxygen unit compressor and the bleeding steam for this purpose is extracted between intermediate- and low-pressure stage (ILS) of the main turbine. Calculations were performed to consider a number of alternative designs, in which the principal issue was to consider capacity and efficiency loss of the power plant resulting from the drive of the compressor from a cryogenic oxygen unit. The results showed that steam from ILS of the main turbine could be used for driving air separation unit (ASU) compressor. However, smaller loss of power and efficiency may be achieved with electrical supply of ASU. An application of oxy-fuel process to power plant will cause a decrease of gross efficiency in power unit by 12% points by using steam from ILS and 11% points by using electric motor for driving ASU. Profitability of oxy combustion technology will be achieved when the CO 2 emissions price reaches a minimum of 52 Euro/EUAs. [ABSTRACT FROM AUTHOR]

Combustion synthesis is capable of producing many types of refractory and ceramic materials, as well as metals, with a relatively lower cost and shorter time frame than other solid state synthetic techniques. TiO2 with Mg as reductant were dry mixed and hand compacted into a 60 mm diameter mold and then combusted under an Ar atmosphere. Depending on the reaction parameters (Mg concentration 2 ≤ α ≤ 4), the thermocouples registered temperatures between 1160°C and 1710°C. 3 mol of Mg gave the optimum results with combustion temperature (Tc) and combustion velocity (Uc) values of 1372°C and 0.26 cm/s respectively. Furthermore, this ratio also had the lowest oxygen concentration in this study (0.8 wt%). After combustion, DC plasma treatment was carried out to spheroidize the Ti powder for use in 3D printing. The characterization of the final product was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and N/O analysis. [ABSTRACT FROM AUTHOR]

In opposed-piston, opposed-cylinder (OPOC) two-stroke diesel engines, the relative movement rules of opposed-pistons, combustion chamber components and injector position are different from those of conventional diesel engines. In this study, the combustion and emission characteristics of the OPOC which is equipped with a common-rail injection system are investigated by experimental and numerical simulation. Different split injection strategies involving different pilot injection/fuel mass ratios and injection intervals were compared with a single injection strategy. The numerical simulation was applied to calculate and analyze the effect of split injection strategies on the combustion and emission after validation with the same experimental result (single injection strategy). Results showed that using split injection had a significant beneficial effect on the combustion process, because of the acceleration effect that enhances the air-fuel mixture. Additionally, the temperature of the split injection strategies was higher than that of single strategy, leading to the nitrogen oxides (NOx) increasing and soot decreasing. In addition, it has been found that the split injection condition with a smaller pilot injection/fuel mass ratio and a medium injection interval performed better than the single injection condition in terms of the thermo-atmosphere utilization and space utilization. [ABSTRACT FROM AUTHOR]

A novel multi-jet burner was built to provide one-dimensional laminar flat flames with a wide range of variable parameters for multipurpose quantitative optical measurements. The burner is characterized by two independent plenum chambers, one supporting a matrix of 181 laminar jet flames and the other supporting a co-flow from a perforated plate with small holes evenly distributed among the jets. A uniform rectangular burned gas region of 70 mm × 40 mm can be generated, with a wide range of temperatures and equivalence ratios by controlling independently the gas supplies to the two plenum chambers. The temperature of the hot gas can be adjusted from 1000 K to 2000 K with different flame conditions. The burner is designed to seed additives in gas or liquid phase to study homogeneous reactions. The large uniform region can be used to burn solid fuels and study heterogeneous reactions. The temperature was measured using two-line atomic fluorescence thermometry and the temperature profile at a given height above the burner was found to be flat. Different types of optical diagnostic techniques, such as line of sight absorption or laser-induced fluorescence, can be easily applied in the burner, and as examples, two typical measurements concerning biomass combustion are demonstrated. [ABSTRACT FROM AUTHOR]

Combustion is a fast oxidation process and exhibits diverse behaviors according to experimental conditions. When there is no natural convection of air, such as in experiments aboard a space shuttle or in a vertically confined system, an unexpected finger-like smoldering combustion develops. In this paper, a reaction-diffusion-advection system that describes smoldering combustion is studied from the viewpoint of computer-aided analysis. In particular, we focus on the traveling wave solutions of the system, which represent the characteristic propagation of combustion. It is revealed that the existence or nonexistence of stable traveling wave solutions determines whether or not a combustion front propagates in a self-sustained way in one space dimension. In two space dimensions, we numerically suggest the existence of a traveling spot solution in which the flow rate is too low to support planar traveling wave solutions. Moreover, we discuss reflection phenomena of a combustion wave when it reaches the boundary of the system. [ABSTRACT FROM AUTHOR]

Properly understanding heat flux characteristics is a crucial prerequisite to efficiently applying a regenerative burner in an aluminum reheating furnace. A series of experiments was conducted in this study in order to establish a database of the best available burners according to furnace temperature, excess air ratio, and flame combustion mode as they affect heat flux characteristics at the burner plane (Z = 0 mm). A heat flux model was developed to estimate heat transfer in the furnace, and the heat flux proportions of the other two horizontal levels (Z = 400 mm and Z = 750 mm) were investigated. The contour profile of heat flux indicates that total heat flux (THF) and radiation heat flux (RHF) increases with furnace temperature increment (900-1100 °C). Low excess air ratio (1.2-1.3, at furnace temperature 1100 °C) not only reduced the heat flux gradient, but also contributed to enlarge high THF areas and the maximum RHF. The flameless combustion mode displayed larger average THF and RHF uniformity than that of conventional combustion mode. Therefore, the burning effect of operating condition 1 (gas velocity, 90 m/s; excess air ratio, 1.2; flameless combustion) is better than the other conditions. A change of furnace temperature and excess air ratio had mildly effect on convection coefficient, but combustion mode was in contrast. The estimated heat flux distribution from the measured heat flux at the whole burner plane was in agreement with the fitted line of the axis of burner B. Although the intercept of the simulated equation was slightly underestimated, the error can be eliminated by improving the experimental conditions. The results presented here similarly apply to all regenerative burners. A comparison of heat flux among the three horizontal levels indicated that the RHF proportion comprised about 80% of the THF at each level, and a slightly increase (21.1 kW/m²) of THF in the high level from the low levels. [ABSTRACT FROM AUTHOR]

The study represents a comprehensive analysis of engine exhaust emission variation from a compression ignition (CI) diesel engine fueled with diesel-biodiesel blends. Biodiesel used in this investigation was produced through transesterification procedure from Moringa oleifera oil. A single cylinder, four-stroke, water-cooled, naturally aspirated diesel engine was used for this purpose. The pollutants from the exhaust of the engine that are monitored in this study are nitrogen oxide (NO), carbon monoxide (CO), hydrocarbon (HC), and smoke opacity. Engine combustion and performance parameters are also measured together with exhaust emission data. Some researchers have reported that the reason for higher NO emission of biodiesel is higher prompt NO formation. The use of antioxidant-treated biodiesel in a diesel engine is a promising approach because antioxidants reduce the formation of free radicals, which are responsible for the formation of prompt NO during combustion. Two different antioxidant additives namely 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,2′-methylenebis(4-methyl-6-tert-butylphenol) (MBEBP) were individually dissolved at a concentration of 1% by volume in MB30 (30% moringa biodiesel with 70% diesel) fuel blend to investigate and compare NO as well as other emissions. The result shows that both antioxidants reduced NO emission significantly; however, HC, CO, and smoke were found slightly higher compared to pure biodiesel blends, but not more than the baseline fuel diesel. The result also shows that both antioxidants were quite effective in reducing peak heat release rate (HRR) and brake-specific fuel consumption (BSFC) as well as improving brake thermal efficiency (BTE) and oxidation stability. Based on this study, antioxidant-treated M. oleifera biodiesel blend (MB30) can be used as a very promising alternative source of fuel in diesel engine without any modifications. [ABSTRACT FROM AUTHOR]

Control and online monitoring of combustion have become critical to meet the increasingly strict pollutant emission standards. For such a purpose, optical sensing methods, like flame emission spectrometry, seem to be the most feasible technique. Spectrometry is capable to provide information about the local equivalence ratio inside the flame through the chemiluminescence intensity ratio measurement of various radicals. In the present study, a 15 kW atmospheric burner was analyzed utilizing standard diesel fuel. Its plain jet type atomizer was operated with both air and steam atomizing mediums. Up to now, injection of steam into the reaction zone has attracted less scientific attention contrary to its practical importance. Spatial plots of OH*, CH*, and C2* excited radicals were analyzed at 0.35, 0.7, and 1 bar atomization gauge pressures, utilizing both atomizing mediums. The C2* was found to decrease strongly with increasing steam addition. The OH*/CH* and OH*/C2* chemiluminescence intensity ratios along the axis showed a divergent behavior in all the analyzed cases. Nevertheless, CH*/C2* chemiluminescence intensity ratio decreased only slightly, showing low sensitivity to the position of the spectrometer. The findings may be directly applied in steady operating combustion systems, i. e., gas turbines, boilers, and furnaces. [ABSTRACT FROM AUTHOR]