Search

Accurately measuring the combustion and destruction removal efficiency of flaring is important when accounting for methane emissions from oil and gas production. Despite this, the amount of experimental data from full-size flares is limited, especially for flares built without air or steam assistance. The use of a single destruction value of 98% is commonly applied. In this paper, we present new empirical measurements of flare efficiency using three common flare designs employed in upstream applications. Combustion products were analyzed using an extractive sampling method. The results demonstrate that whilst destruction efficiencies in excess of 98% are achievable, if the gas composition falls below a critical heating value of ~300 BTU/scf, the efficiency deteriorates leading to elevated methane emissions. This is further complicated by accurately measuring the flow of combustible gas and the impact of crosswinds. In an operational setting, continuous tracking of flare conditions is therefore a key resource in reducing methane emissions but further work is required to standardize how continuous performance tracking is evaluated if such measurements are to attain full traceability. [ABSTRACT FROM AUTHOR]

An experimental stagnation pressure measurement technique is presented for a rotating detonation combustor (RDC). Schlieren imaging enables rotating detonation wave passage to be correlated with oscillations observed in the under-expanded exhaust plume. By measuring the spatiotemporal variation in exhaust plume divergence angle, stagnation pressure measurements of the RDC were acquired at a rate of 1 MHz. Combustor mass flux was varied between 202 and 783 kg/m2s, producing equivalent available pressures (EAPs) in the range of 3.42–13.5 bar. Time-averaged stagnation pressure measurements gathered using this technique were in agreement with the measured EAP within ±1.5%. Time-resolved stagnation pressure measurements allow for the pressure ratio produced across detonation wave cycles to be determined. For the conditions tested, detonation pressure ratios and wave speeds decreased while increasing the mean operating pressure of the combustor. Numerical modeling of the conditions tested indicates that the decrease in pressure ratio and wave speed is a result of elevated levels of combustion prior to the detonation wave arrival (i.e., "preburning"). Simultaneous OH* chemiluminescence measurements within the combustion chamber show an increase in preburned heat release relative to detonative heat release for increasing operating pressures of the RDC, in agreement with the results of the numerical model. Modeled chemical kinetic timescales decrease by approximately the same magnitude by which the preburning mass fraction increased in the range of operating pressures tested, suggesting that the faster reaction rates associated with higher pressure combustion may be the reason for increased preburning within the combustor. [ABSTRACT FROM AUTHOR]

The effects of the burnt-to-unburnt temperature ratio (T b / T u) (reciprocal density ratio) on thermoacoustic combustion instability were investigated in a hydrogen-rich ram combustor by controlling the inlet air temperature under cruising conditions. Steady and unsteady combustion dynamics were investigated with the simultaneous measurement of combustion pressure and near-infrared (NIR) emissions. Time-resolved NIR images were analyzed using dynamic mode decomposition (DMD) to extract modes of the combustion instability, which show two oscillation modes: longitudinal (500 Hz) and flame-vortex interaction modes (2000 Hz) with a Strouhal number of approximately 0.5. The thermoacoustic combustion instability was not excited at T b / T u = 3.3, but was excited at T b / T u = 2.6 and 2.9. The DMD modes show that the structure of the vortex mode is similar to that of the fourth longitudinal mode at T b / T u = 2.6 and 2.9, indicating that the coupling of the vortex and the fourth longitudinal modes excited the thermoacoustic combustion instability. • The burnt-to-unburnt temperature ratio T b / T u influenced thermoacoustic instability (TI) in a hydrogen-rich combustor. • Dynamic mode decomposition analysis extracted a longitudinal mode (500 Hz) and a vortex mode (2000 Hz). • At low T b / T u , TI was excited owing to the similar structures of the vortex and fourth longitudinal modes. • Vortex mode was changed by the enhanced vortex formation near the injectors at high T b / T u. • At high T b / T u , TI was not excited owing to the low correlation between the vortex and fourth longitudinal modes. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) is emerging as a potential favoured fuel for longer range decarbonised heavy transport, particularly in the marine sector, predominantly due to highly favourable characteristics as an effective hydrogen carrier. This is despite generally unfavourable combustion and toxicity attributes, restricting end use to applications where robust health and safety protocols can always be upheld. In the currently reported work, a spark ignited thermodynamic single cylinder research engine equipped with gasoline direct injection was upgraded to include gaseous ammonia port injection fuelling, with the aim of understanding maximum viable ammonia substitution ratios across the speed-load operating map. The work was conducted at varied effective compression ratios under overall stoichiometric conditions, with the spark timing re-optimised for maximum brake torque at all stable logged sites. The experiments included industry standard measurements of combustion, performance, and engine-out emissions (including NH3 "slip"). With a geometric compression ratio of 11.2:1, it was found possible to run the engine on pure ammonia at low engine speeds (1000-1800 rpm) and loads of 12 bar net IMEP. When progressively dropping down below this load limit an increasing amount of gasoline co-firing was required to avoid engine misfire. When operating at 1800 rpm and 12 bar net IMEP, all emissions of carbon (CO2, CO, unburned hydrocarbons) and NOx decreased considerably when switching to higher NH3 substitution ratios, with NOx reduced by ~ 45% at 1800 rpm/12 bar when switching from pure gasoline to pure NH3 (associated with longer and cooler combustion). By further increasing the geometric compression ratio to 12.4 and reducing the intake camshaft duration for maximum effective compression ratio, it was possible to operate the engine on pure ammonia at much lower loads in a fully warmed up state (e.g., linear low load limit line from 1000 rpm/6 bar net IMEP to 1800 rpm/9 bar net IMEP). Under all conditions, the indicated thermal efficiency of the engine was either equivalent to or slightly higher than that obtained using gasoline-only due to the favourable anti-knock rating of NH3. Ongoing work is concerned with detailed breakdown of individual NOx species together with measuring the impact of hydrogen enrichment across the operating map. [ABSTRACT FROM AUTHOR]

α‐Si3N4 powder was prepared by combustion synthesis method. The propagation characteristics of combustion wave were investigated by thermocouple temperature measurement and "resistance—combustion wave displacement response device." The results show that the combustion reaction takes place in a narrow area, and there is a maximum temperature gradient of 180°C/mm in the combustion front. The "resistance—combustion wave displacement response device" was innovatively used to realize the in situ measurement of combustion wave propagation process. The test results showed the pulse combustion mode in which the combustion front took 10 s as a cycle, and the quantitative data of Si–N2 discrete combustion characteristics were obtained for the first time. [ABSTRACT FROM AUTHOR]

As a high energy density hydrogen-rich carrier, ammonia (NH3) is a highly promising carbon-free fuel. The large-scale industrial application of NH3 is limited by its low reactivity and high NOx emission. In this work, the flame and emission characteristics of ammonia/methane (NH3/CH4) non-premixed combustion were investigated under ultrasonic excitation. An experimental system was designed and built, including non-premixed combustion system, loading ultrasonic system, deflectionmography temperature measurement system and flue gas measurement system. Combustion and measurement experiments at different ultrasonic frequencies and NH3/CH4 blending ratios were carried out. Flame images and flue gas species concentrations under ultrasonic excitation were acquired. The 3-D temperature field was reconstructed. The influence of ultrasonic excitation at different frequencies on flame characteristics, flame temperature field and emission characteristics of the combustion process was analysed. The mechanism of NH3/CH4 combustion enhancement and emission reduction was revealed when the flame was ex-cited by ultrasonic waves. Results showed that part of the hydrocarbon fuels was replaced by NH3 to reduce CO2 emission. The height and color of the NH3/CH4 flame were changed and the high temperature area of the flame gradually expanded as ultrasonic acted on the flame. As ultrasonic frequency increased, the emission concentrations of unburned CH4, unburned NH3, and NO decreased significantly. The flame was ex-cited by ultrasonic waves, which reduced its local equivalent ratio, improved combustion efficiency and suppressed NOx generation. [ABSTRACT FROM AUTHOR]

Aluminum is characterised by its high calorific value, stable performance, and abundant reserves. It is a commonly used additive in solid propellants that are widely used in aerospace and underwater propulsion applications. As aluminum is a key component of these solid propellants, combustion temperature measurement of aluminum particles is crucial in investigating their combustion characteristics. This paper presents a method to determine the combustion temperature of aluminum particles in solid propellants. A combination of radiation imaging and Monte Carlo probability simulation is applied in the proposed method. Further, a numerical model is established to determine the surface temperature of aluminum particles. The method is validated through numerical simulation considering a target with a pre-set temperature distribution, as well as a practical implementation in solid-propellant combustion experiments. Results of the experimental analysis establish the reliability of the proposed method and also demonstrate the method's ease of operation, good practicability, and potential for future application. • A method to determine the combustion temperature of aluminum particles is proposed. • The proposed method is based on Planck's radiation law and Monte Carlo simulation. • The method validated through numerical simulation with pre-set temperature and experiments. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate and high-speed transient surface-temperature measurements of combustion devices including internal combustion (IC) engines, gas turbines, etc., provide validation targets and boundary conditions for computational fluid dynamics models, and are broadly relevant to technology advancements such as performance improvement and emissions reduction. Development and demonstration of a multi-infrared-channel pyrometry-based optical instrument for high-speed surface-temperature measurement is described. The measurement principle is based on multi-spectral radiation thermometry (MRT) and uses surface thermal radiation at four discrete spectral regions and a corresponding emissivity model to obtain surface temperature via non-linear least squares (NLLS) optimization. Rules of thumb for specifying the spectral regions and considerations to avoid interference with common combustion products are developed; the impact of these along with linear and non-linear MRT analysis are assessed as a function of temperature and signal-to-noise ratio. A multi-start method to determine the MRT-solution global optimum is described and demonstrated. The resulting multi-channel transient pyrometry instrument is described along with practical considerations including optical-alignment drift, matching intra-channel transient response, and solution-confidence indicators. The instrument demonstrated excellent >97% accuracy and >99% 2-sigma precision over the 400–800 °C range, with ~20 µs (50 kHz, equivalent to 0.2 cad at 2000 RPM IC-engine operation) transient response in the bench validation. [ABSTRACT FROM AUTHOR]

This article discusses current testing methods for motor vehicle engines. Traction engines have so far been tested, for example, according to WLTP (Worldwide Harmonized Light Vehicle Test Procedure) driving tests, but due to the "VW—gate" incident, these are now to be supplemented by RDE (Real Driving Emissions) tests, conducted under real road conditions. The analyses of the state of knowledge and the directions of research to date unequivocally indicate the need for the construction of a stand that allows: testing of a complete vehicle admitted to traffic; testing of a motor vehicle with the possibility of simulating real operating conditions; load setting with the possibility of its regulation; feeding the engine with various fuels; modification of the software of controllers having a direct impact on the control strategies of the engine; transmission and traction control system; reading, recording and analysis of the parameters of the operation of control systems in real time; detailed recording and analysis of the combustion process occurring directly in the combustion chamber; and the measurement of emitted toxic substances. On a bench with the above features, tests were carried out on a diesel motor vehicle, which were based on recording changes in the parameters of the combustion and injection process. The tests were conducted under static and dynamic conditions. Tests under static conditions were conducted on a chassis dynamometer. They consisted of indicating the engine for different fuel dose control maps. The vehicle equipped with the test engine was driven at a constant speed on the chassis dynamometer and loaded with a drag force of 130 Nm. Tests under dynamic conditions were conducted under real traffic conditions. They were limited to the presentation of results under static conditions. The main results of the tests are given in the conclusion and include a general summary. In particular, the presented results of the diesel tests demonstrate an attempt to adapt the engine to co-power with hydrogen. [ABSTRACT FROM AUTHOR]

• A current literature overview on biomass oxy-combustion identifies research gaps. • Pulverized walnut shell combustion investigated by optical and sampling methods. • Optical measurements provide the size statistics for the whole particle ensemble. • Burnout was analyzed using a solid sample probe for chemistry and porosity. • Temperature, size and sampling data combined in one comprehensive data set. Despite the extensive literature on single-particle biomass combustion measurement, there is a significant gap between the abundance of conducted experimental investigations and the inadequacy of the resulting database for calibrating predictive burnout models. This research aims to address this gap by providing an experimental database for single-particle combustion of walnut shells, chosen as a representative lignocellulosic biomass, in a laminar flow reactor for oxy-fuel combustion. Eight different oxy-fuel atmospheres were examined. A stereoscopic imaging system, utilizing four intensified CCD cameras, enables in-situ measurements of temperature, size, shape, velocity and residence time of solid fuel particles. The system's optical resolution is approximately 10 µm and its temporal resolution is 1 μs. In addition to the optical measurements, partially converted solid samples were extracted from the reactor with a sampling probe. The elemental composition, the proximate analysis, pore evolution during the burnout and the morphology of particles were analyzed using samples collected at different residence times. Notably, walnut shells always ignite heterogeneously in oxy-fuel atmospheres and the volatile flame is of low luminosity. With increasing burnout, spheroidization of particles occurs. The novel dataset is presented, compared, and discussed alongside results from current literature. [ABSTRACT FROM AUTHOR]

In the present work, an optical sensor was developed and calibrated for the purpose of non-intrusive equivalence ratio measurements in combustion systems. The sensor incorporates a unique four-line, single-sensor chemiluminescence imaging-based approach, which relies on the ratio of C2* and CH* radical-species intensities to obtain measurements of equivalence ratios. The advantage of the four-line sensor is the use of additional filtering to mitigate broadband luminescence signals, and its improvements over conventional two-line chemiluminescence diagnostics are discussed. The sensor was calibrated using a premixed bluff-body jet burner with a propane–air flame operating over a wide range of equivalence ratios. The results showed that the four-line processing technique improved the signal-to-noise ratio of the chemiluminescence images for all test cases. Calibrations of C2*/CH* intensity ratio to equivalence ratio were developed for both the four-line and two-line techniques. The calibrations were then used to create maps of local equivalence ratios in the flame-holding region. The maps revealed a non-uniform field of equivalence ratios due to the nature of the radical-species intensity profiles within the flame. Therefore, special consideration is required for calibration in order to accurately quantify equivalence ratios and apply these to diffusion flames. [ABSTRACT FROM AUTHOR]

In the work, the combustion regimes of iron particles (d10 = 4.7 µm) in a laminar pre-mixed flame (LPF) and in an axisymmetric laminar diffusion flame (LDF) are studied. For (LPF), we studied the effect of variations in gas suspension of the concentrations of fuel Cf = 0.4 ÷ 0.6 kg/m3 and oxygen CO2 = 21 ÷ 40%, and for (LDF), pure oxygen blowing and variation in the iron concentration Cf = 0.4 ÷ 1.5 kg/m3. The results of particle temperature measurements in the combustion zone of LPF and LDF, the dispersed and phase composition of the combustion products (depending on the concentration of fuel and oxidizer) are presented. It is shown that, under certain conditions, iron particles in LPF switch to a "high-temperature" diffusion mode of combustion. This mode is accompanied by intensification of gas-phase reactions and leads to a two-mode particle size distribution of combustion products. In this mode of combustion of a gas suspension (at temperatures much lower than the boiling point of iron), the mass yield of a nanoscale fraction of combustion products reaches tens of percent and increases with increasing oxygen concentration in LPF. This mode of iron particles combustion was not observed in LDF. The features of the thermal structure of the diffusion dust flame are analyzed. It is shown that in LDF the burning time of metal particles in the diffusion mode is proportional to the particle radius r p ( \~ r p in the kinetic mode), and should depend on the concentration of fuel and the size of the burner. [ABSTRACT FROM AUTHOR]

We report micrometric imaging measurements of the ignition of micron-sized aluminum (Al) wires and the consequent combustion processes of single micron-sized Al droplets in hot steam and steam with oxygen. The specially designed flames were anchored on a modified burner where a small central H 2 /O 2 diffusion flame in the center jet provided a hot flow (>2330 K) for Al ignition, and the diffusion flame together with a laminar co-flow of premixed H 2 /N 2 /O 2 flame provided the vitiated flow of desired combustion environment. As soon as the horizontally arranged Al wire was moved to the center hot jet, a high-speed color camera was triggered to record the transient event of the ignition and combustion process. The high imaging quality and spatial resolution allow direct observation of the structure of the burning particles, i.e., the liquid core, the bright flame front encapsulating the center droplet, and the coalescent alumina agglomerates downstream above the burning Al droplets. A distinct thin condense sheet was observed defining the flame front in all symmetric and asymmetric combustion modes, indicating that homogeneous oxidation dominates the heat-release reactions as a diffusion flame. A color ratio RGB pyrometry was calibrated to provide temperature distribution over the burning particles. In the steam condition, the center droplet temperature in the symmetric phase was analyzed to be ∼2650 K and the temperature of the flame front ∼3400 K, while in the oxygenated environments, the droplet temperature was evaluated to be ∼2790 K, and the temperature of the flame front ∼4150 K. The transient temperature evolution of different parts of the burning elements was recorded and analyzed. To the authors' awareness, the current study represents the first structure-resolved temperature measurement of the combustion of single aluminum particles in high-temperature steam. These measurements can provide unprecedented spatiotemporally resolved information on Al combustion for improved insight into the governing mechanism. [ABSTRACT FROM AUTHOR]

Compared to the ordinary RDX, nano‐sized RDX has many more excellent properties. Therefore two kinds of CMDB propellant were prepared for comparison. One is the normal CMDB propellant called M‐CMDB propellant, the other is N‐CMDB propellant which adds nano‐sized RDX to CMDB propellant. The morphology characterization, tensile properties, sensitivity, and combustion performance of the propellants were investigated, the results for N‐CMDB propellant were compared with that for the normal one. It has been found that the interface of N‐CMDB propellant showed no stratification and fewer overall defects than the normal one. The value of σm and ϵm for N‐CMDB propellant are increased by 32.6 % and 25.2 % at 323.15 K, respectively. At 293.15 K, the σm and ϵm values of N‐CMDB propellant also increased by 25.4 % and 46.9 % and increased by 17.5 % and 23.7 %, respectively, at 233.15 K. The friction and impact sensitivities of N‐CMDB propellant are decreased by 51.3 % and 50.4 %, respectively. The TG/DSC study indicated that, compared with M‐CMDB propellant, the thermal decomposition peak temperature of N‐CMDB propellant is advanced, and the apparent activation energy is reduced by about 6.0 % to 144.3 kJ ⋅ mol−1. Combustion performance measurements were carried out. It was observed that nano‐sized RDX is a good burning rate enhancer, because of the burning rate coefficient value of N‐CMDB propellant is relatedly increased by 36.9 %. Besides, the pressure exponent of N‐CMDB propellant is relatively decreased by 21.6 %. All the results indicate that the application of nano‐sized RDX will help to improve the comprehensive performance of CMDB propellant. [ABSTRACT FROM AUTHOR]

Attempts were made to reproduce the laboratory measurements of flameless combustion systems using numerical simulation tools, for different chambers designs. In many cases, a significant discrepancy is reported between the experimental measurements and the numerical results. In this work, we have successfully reproduced the reported experimental results (velocity field, temperature field, and the outlet dry NOx emissions) of the "FOUR" MILD combustion facility (proposed by C. Rottier). An acceptable accuracy was achieved in two reference test cases. A concise discussion is presented on the available literature on the subject of numerical modeling for the flameless combustion mode. The use of two turbulence models was explored (standard k-ε, and modified k-ε), along with two kinetic mechanisms (a global 2-step CH4 combustion mechanism, and the more detailed KEE-58 mechanism). The commercial ANSYS FLUENT® software was used in these simulations. The results of seven different modeling setups are presented, comparing the predictions of temperature fields, and NOX emissions. Features such as the onset of premature ignition and the reactants entrainment ratio are also discussed. Our results show that the most accurate model setup employs the following: SKE – KEE-58 – EDC with a reduced volume fraction constant. In regards to reproducing the measurements from the "FOUR" facility, we are not aware of a similar research that runs a concise discussion on the predictions of such broad and different modeling setups. [ABSTRACT FROM AUTHOR]

• Single-cylinder engine (SCE) experiment using renewable diesel and methanol as fuels. • Dual-fuel combustion and emissions performance comparison with conventional diesel combustion. • Effect of different methanol substitution rates at different engine load conditions. Methanol (MeOH) and renewable diesel (RD) are being considered promising alternative fuels for the de-fossilization of internal combustion engines (ICE). This study provides an experimental investigation on the use of both fuels under dual-fuel combustion mode: port fuel injection (PFI) of MeOH and direct injection (DI) of RD. The combustion mode is labeled as RMDF (renewable diesel methanol dual fuel). The experiment was performed in a heavy-duty single-cylinder engine (SCE) equipped with combustion and emissions measurements and analysis for engine efficiency and emissions of soot and NO X (oxides of nitrogen). MeOH substitution rate, which is the mass ratio of injected MeOH fuel to total injected fuels of both MeOH and RD, was varied to study its effect on engine efficiency and emissions. Different MeOH substitutions were tested from low (6.9 bar gIMEP) to full (23.5 bar gIMEP) engine load conditions at a fixed engine speed of 1200 RPM. Test results showed that higher MeOH substitution rates can reduce NO X emissions effectively while improving engine thermal efficiency. However, a higher MeOH substitute rate can result in longer ignition delay at low load, and increased emissions of carbon monoxide (CO) and unburned hydrocarbon (UHC). Increased maximum pressure rise rate (MPRR) at high load condition was observed as the MeOH substitution rate increased. MPRR is not sensitive to the change in MeOH at low load condition. While ignition delay became longer at low load, it was shorter at high load as MeOH substitution rate increased. Overall, the results from this study suggest that RMDF can be considered as an option to achieve a cleaner and more efficient engine. However, further optimization of combustion designs and engine operating strategy need to be considered to improve combustion loss from RMDF emissions, possibly due to the lower reactivity of MeOH. [ABSTRACT FROM AUTHOR]

• Measuring the enthalpy of combustion of methane gas with a reference gas calorimeter. • Description of reference gas calorimeter system elements. • Comprehensive uncertainty calculation for enthalpy of combustion measurement. • Determination of enthalpy of combustion of methane with low uncertainty. • Importance of temperature measurements in enthalpy of combustion calculations. Natural gas is a plentiful and adaptable energy source among other gases that is used all over the world with an increasing demand nowadays. It is therefore of utmost importance to measure the energy content of the natural gas with high precision for both users and sellers. In this study, methane gas, the main component of natural gas, was combusted using the reference gas calorimeter developed at TUBITAK UME (The Scientific and Technological Research Council of Turkey) - (National Metrology Institute) to determine the enthalpy of combustion. The objective was to measure the enthalpy of combustion of the methane, perform a detailed uncertainty calculation and to compare the enthalpy of combustion of the methane specified in ISO 6976:2016 with the obtained experimental results. The reference gas calorimeter was designed using the temperature, mass, power, flow control, waste water absorption, and waste gas measurement systems with the highest precision and circulating water bath with temperature control insulated so as not to exchange heat from the external environment. All measurements were performed with the instruments having calibration certificates. Experiments were carried out at the temperature of 298.15 K and a constant pressure (101.325 kPa) using the methane with a purity of 99.995 % as a reference gas. The mass of the burnt methane in combustion process was approximately 10-3 kg. As a consequence of the measurements, mean experimental enthalpy of combustion was obtained as −55518.2 kJ kg−1 with the error of 0.2 % (k = 2). The evaluations indicated that the largest source of error in the enthalpy of combustion measurements originated from the temperature and mass measurements. [ABSTRACT FROM AUTHOR]

This work implements astigmatic dual-beam interferometric particle imaging (ADIPI) in propellant combustion diagnostics to enable the measurement of the three-dimensional (3D) spatial position and particle morphology of opaque particles. The ADIPI allows the discrimination of different substances, such as metal droplets, flames, and pyrolysis residues. A general theoretical model based on the generalized Huygens-Fresnel integral and the ray transfer matrix model is developed to describe the identification of ADIPI signals for regular and irregular particles. An experimental system combining a 13 kHz time-resolved ADIPI with digital in-line holography (DIH) is built to enable simultaneous measurements of the propellant combustion field. The typical ADIPI signals presented by different substances in the combustion field are analyzed by comparing the experimental results of DIH. The time-resolved 3D trajectory reconstruction of burning particles and the measurement of irregular particle size and morphology are realized. Due to the effect of the flame, the average deviation of the depth locating of the particles is 1.4 mm with a standard deviation of 1.0 mm. The average deviation value of the depth position relative to the measured distance is 1%. In propellant combustion measurements, the motion of burning particles can be accurately determined, proving its feasibility and practicality. [Display omitted] • ADIPI is applied to propellant combustion diagnostics. • Theoretical model and experimental study are both carried out. • 3D trajectory, particle size and morphology of burning particles are measured. [ABSTRACT FROM AUTHOR]

Energy generation from renewable sources in the power sector keeps constantly increasing. This raises the demand for fast and flexible large-scale storage technologies. Steam generation via stoichiometric combustion of hydrogen and oxygen within a steam cycle is a promising way to recombine both gases, which can be generated by electrolysis utilizing excess renewable energy. At the same time, this technology could provide balancing and spinning network reserves. A crucial parameter of this approach is the combustion efficiency, since residual hydrogen or oxygen can damage downstream components of the power plant steam cycle. The current paper investigates the combustion of hydrogen and oxygen under steam diluted conditions. Flow field, mixing, flame types and combustion efficiency are assessed. The combustion efficiency measurement is very challenging in this case, as the combustor products consist mostly of pure steam and cannot be dried for conventional gas analysis. This is solved by an in-situ measurement method to quantify the combustion efficiency. Initial results of this approach are also presented in the current work. • A characterization of a hydrogen oxyfuel combustor under steam-diluted conditions. • First in-situ analysis of combustion efficiency and gas residuals H2 oxyfuel flame. • Combining equivalence ratio control and in-situ oxygen concentration measurements. • The burner reveals high combustion efficiency over a wide range of steam-dilution. • The combustor reveals two flame types: The swirl-stabilized and the jet flame. [ABSTRACT FROM AUTHOR]

A validation of the ISO 787-23 method for measuring true density on reference black carbon samples and combustion emitted particles is proposed and compared to alternative methods. New measurements of true density on samples representative of fire emissions at different scales are presented and discussed, according to their respective experimental uncertainties. These results are compared to the values of soot true densities reported in the literature. An interesting correlation between the true density of combustion emitted particles and the Organic Carbon (OC) content is observed and commented: the true density significantly decreases as OC content increases. Three different ranges of true densities are then proposed as a function of the OC/Total Carbon (TC) ratio of combustion emitted particles. For low OC contents (i.e. below 5%) and high OC contents (i.e. above 20%), respective mean values of 1834 ± 187 kg/m3 and 1285 ± 217 kg/m3 are proposed. For intermediate OC content values, a fit is applied based on a mixing law. Finally, there is a discussion on the relevance of using these values for true densities of combustion emitted particles for temperatures representative of those reported in industrial fires, ranging from 25 °C to 240 °C. Image 1 • Validation of two measurements methods of combustion emitted true density. • Application to 15 different combustion emitted particles (burner, fire's soot, aircraft). • Combustion emitted particles true density decreases with increasing OC/TC ratio up to 20%. • Mixing law allows to determine organic fraction density. • Poor influence, on true density, of temperature up to 240 °C. [ABSTRACT FROM AUTHOR]

Computer‐aided‐learning has been found to improve notably the learning efficiency as compared with classical teaching. In this study, an interactive Matlab application has been developed to be used when teaching combustion thermochemistry in engineering degrees. The use of this tool in practical sessions allows the students to concentrate on understanding the links between the boundary conditions of a combustion process and the corresponding outputs in terms of species composition and temperature. Moreover, the students can check the differences between the results obtained from a complex calculation (with the interactive tool) and those obtained by means of the simplified calculations performed during the theoretical lessons and written exams. The analysis of the outcomes after several years using this tool revealed that the students are generally satisfied with the practical session, and the analysis of the marks confirms the robustness of the methodology proposed. [ABSTRACT FROM AUTHOR]

The use of fire constitutes an essential cultural adaptation to cold, and archaeological evidence for fire can be expected in high-latitude and high-elevation regions successfully inhabited by modern humans. At Cuncaicha rockshelter (4480 m above sea level, or masl) in the southern Peruvian Andes, evidence for fire is present from the earliest occupation, dating to the Terminal Pleistocene (∼12,500–11,200 cal BP). Yet, the site contains relatively few identifiable carbonized macrobotanical remains useful for identifying plants employed as combustible fuel. Based on a comprehensive review of nearly 40 early Andean archaeological sites above 2500 masl, little is known about fuels used for combustion. To understand fuel selection strategies at Cuncaicha, we conducted a combustion field experiment, evaluating the three highland plant taxa most likely to have been used as combustible fuels: Polylepis rugulosa (queñua) tree branches, Parastrephia spp. (tola) woody shrubs, and Azorella compacta (yareta) cushion plants. Temperature measurements informed on the combustion characteristics and efficiency of each fuel. We then compared the experimentally-produced fire residues to the geoarchaeological evidence from Cuncaicha. The resinous cushion plant yareta, endemic to the high Andes, may have been the primary fuel used at Cuncaicha based on the experiment outcome and the geoarchaeological evidence. Due to its high-temperature and complete combustion, yareta leaves little to no macrobotanical evidence, thus its identification at other Andean sites may require a multi-methodological approach. Because the geographic range of this plant corresponds with most early archaeological sites in the high Andes, yareta may have been a key resource enabling early settlement throughout the region. • Review indicates widespread fire use in Late Pleistocene occupations of high Andes • Experimental combustion suggests multiple effective fuels in Puna ecoregion • Microscopic ash analysis suggests early use of Azorella compacta cushion plants • Multiple, highly combustible Andean fuels supported initial settlement process [ABSTRACT FROM AUTHOR]

• The RPF of marine waste plastics was not suitable for dedicated fixed-bed combustion. • RPF cofired with wood pellets at 20 wt% or larger achieved stable flame propagation. • For RPF-WP blend (6:4), typical three combustion regimes of fixed bed were identified. • The fuel-rich gas released from the bed needed additional air for complete oxidation. • Key combustion parameters were derived for design variables of a grate furnace. Energy recovery from marine plastic waste after the collection and pretreatment of refuse plastic fuel (RPF) offers a practical measure to prevent the formation of microplastics, which pose a threat to marine biota and human health. This study investigated the fixed-bed combustion of RPF by visual observation and detailed measurement of the key combustion parameters. Unlike the fluff form, densely compacted RPF particles were not suitable for dedicated combustion in a fixed bed reactor because they melted and subsequently blocked the air passages. However, cofiring with 20 wt% or a larger amount of wood pellets (WP) successfully stabilized the flame propagation because the WP particles secured the air passages. The RPF-WP blend (6:4) exhibited the characteristic behaviors of fixed bed combustion in which the downward flame propagation and burning rate accelerated with increase in air flow rate and reached a peak. The combustion gas was highly fuel-rich mainly due to the hydrocarbons released from RPF, indicating that a large amount of additional air is required to complete oxidation above the bed. The experimental approach of this study to derive combustion parameters for particular RPF-biomass mixtures can be useful for guiding the primary design variables of industrial-scale grate furnaces. [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]

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]

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]

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]

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]

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]

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]

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]

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]

Poor sanitation is one of the major hindrances to the global sustainable development goals. The Reinvent the Toilet Challenge of the Bill and Melinda Gates Foundation is set to develop affordable, next-generation sanitary systems that can ensure safe treatment and wide accessibility without compromise on sustainable use of natural resources and the environment. Energy recovery from human excreta is likely to be a cornerstone of future sustainable sanitary systems. Faeces combustion was investigated using a bench-scale downdraft combustor test rig, alongside with wood biomass and simulant faeces. Parameters such as air flow rate, fuel pellet size, bed height, and fuel ignition mode were varied to establish the combustion operating range of the test rig and the optimum conditions for converting the faecal biomass to energy. The experimental results show that the dry human faeces had a higher energy content (∼25 MJ/kg) than wood biomass. At equivalence ratio between 0.86 and 1.12, the combustion temperature and fuel burn rate ranged from 431 to 558 °C and 1.53 to 2.30 g/min respectively. Preliminary results for the simulant faeces show that a minimum combustion bed temperature of 600 ± 10 °C can handle faeces up to 60 wt.% moisture at optimum air-to-fuel ratio. Further investigation is required to establish the appropriate trade-off limits for drying and energy recovery, considering different stool types, moisture content and drying characteristics. This is important for the design and further development of a self-sustained energy conversion and recovery systems for the NMT and similar sanitary solutions. [ABSTRACT FROM AUTHOR]

Driven by issues such as global warming, there is currently great interest and significance in developing zero carbon-emission internal combustion engines. Limited by structural and sealing requirements, there are no experimental studies related to combustion velocity measurement of the hydrogen-fueled Wankel rotary engine (HWRE) with excellent power performance, which is important to investigate its knock characteristic. In this work, a combustion velocity measuring method of dual spark plug HWRE is proposed, besides the obtained combustion, flow and flame velocities are correlated with the knock to explore their influence on the HWRE knock characteristics. The study found that adopting dual spark plugs in HWRE is necessary to reduce the negative impact of the flame not being able to propagate against the flow field. Besides, excess air ratio affects the combustion velocity of HWRE by changing the flame velocity, while the engine speed affects the combustion velocity of HWRE by changing the flow velocity, which basically does not affect the flame velocity. The knock level of HWRE is influenced by its flame velocity and flow velocity, both of which are positively correlated to the knock intensity and the latter has a more significant effect. • A method of measuring Wankel rotary engine combustion velocity is proposed. • Quantifying the combustion, flow and flame velocity of hydrogen Wankel rotary engine. • Investigating the influence of excess air ratio and engine speed. • Quantifying the relationship between knock intensity and above three velocities. [ABSTRACT FROM AUTHOR]

• Real-time measurement of flame temperature and heat release rate. • Emission spectroscopy thermometry. • Designed for combustion oscillation active control systems. Accurate and real-time measurement of combustion chamber flame temperature and heat release rate (HRR) is critical for active control of combustion instability. This paper developed a flame temperature and HRR sensor based on radical emission spectroscopy. The sensor contains two optical acquisition channels with different responses to detect the spectral intensities of two different bands of hydroxyl (OH*). Optical acquisition channels contain optical filters, photodiodes, and photocurrent amplifier circuits. The single band spectral intensity can reflect the fluctuation of the HRR. The flame temperature can be calculated by the ratio of the spectral intensities of the two bands. The optimal detection bands are determined as 310.2–320.1 nm and 303.7–309.0 nm based on the genetic algorithm. In the temperature range of 1700–1900 K, the sensor achieved a precision of ±10 K, and the sensor successfully detects the HRR oscillation with a main frequency of 326 Hz. [ABSTRACT FROM AUTHOR]

Limited research has been conducted on the burning characteristics of live fuels, which are commonly assumed to behave like moist dead fuels. We use small-scale laboratory calorimetric experiments to investigate the differences in fire dynamics between live and dead Pinus halepensis needles. The study includes laboratory-aged samples and different moisture conditions (fresh or oven dry). A series of ten fire behaviour parameters are extracted from the measurements to identify and quantify differences. The main parameters are the following: time to ignition; flaming time; mass loss pre-ignition, during flaming, and during smouldering; peak power; effective heat of combustion; mean and peak CO/CO2; and radiative fraction. Using these parameters, we show that the most flammable samples are fresh dead and aged needles, followed by dry dead and dry live needles. The least flammable is fresh live needles. Live needles ignite about four times slower, and burn with ~60% lower power and ~50% lower heat of combustion than dead needles. Aged needles resemble most closely the behaviour of dead needles, but many fire behaviour parameters were significantly different. The results confirm the importance of moisture content in the burning behaviour of pine needles, but the differences between live and dead samples cannot be explained solely in terms of moisture but require consideration of plant chemistry and sample drying. © 2015 The Authors. Fire and Materials published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

We present a facile, spontaneous, and surfactant-free method to controllably self-assemble aluminum and bismuth trioxide nanoparticles through the introduction of graphene oxide as a self-assembly directing agent. The self-assembled nanocomposites demonstrate significant combustion performance improvements in comparison to randomly mixed aluminum and bismuth trioxide nanoparticles with enhanced pressure generation from 60 to 200 MPa, pressurization rate from 3 to 16 MPa μs−1, burning rate from 1.15 to 1.55 km s−1, and specific impulse from 41 to 71 s. The sensitivity of the self-assembled aluminum and bismuth trioxide to electrostatic discharge was reduced by four orders of magnitude, without decreasing the combustion performance. Graphene oxide directed self-assembly can be used to synthesize nanocomposites with diverse combustion properties and controlled ignition sensitivity, which lays the foundation for preparing multi-functional, highly-reactive, combustion systems in the future. [ABSTRACT FROM AUTHOR]

• The dependencies of mean reaction rate on the EDC constants are presented. • A CH 4 MILD combustion furnace is successfully predicted with the EDC constant ratio of 4. • The EDC constant ratio of 2 is recommended for the CH 4 conventional combustion. • Large differences of excess temperature are found for MILD and conventional combustions. • A criterion is suggested for the MILD combustion attainment. The indisputable wide use of the Eddy Dissipation Concept (EDC) indicates that the mean reaction rate is reasonably modeled for MILD (Moderate or Intense Low-oxygen Dilution) and conventional combustions. However, RANS (Reynolds-Averaged Navier-Stokes) modelling with the standard EDC constants tends to over-predict maximum temperatures when applied to the MILD combustion regime. Therefore, there is a modification need of the EDC constants to predict properly the mean reaction rate, and then the maximum temperatures. The relation of the mean reaction rate and the EDC constants, including the primary and the secondary, is presented. A lab-scale methane MILD combustion furnace (MCF) with non-preheated air from literature is chosen for the validation of the EDC constants. The modification is done with one of the secondary EDC constants ranging from 1 to 28 where the primary constant is kept at C D 1 = 0.1357. Predictions with the secondary EDC constant of 4 agree quite well with the measurements of the MILD combustion in this furnace. The modified EDC constant of 2 are suggested for the predictions of the conventional combustion in this furnace. Finally, based on the excess temperature or the normalized root mean square excess temperature (NRET), a criterion for the attainment of MILD combustion in this furnace is suggested. [ABSTRACT FROM AUTHOR]

• A novel low-load stable combustion technology is applied on a 600MWe FW down-fired boiler. • 33% rated load stable combustion without oil support is achieved. • Full-scale industrial measurements are carried out at 200, 240 and 540MWe. • Combustion and NOx formation characteristics at high and low load are contrastively studied. The randomness and intermittence of solar and wind power generation require coal-fired thermal power boilers that have a low-load stable combustion capacity. This study proposed a novel low-load stable combustion technology in which the oil secondary air flow is arranged parallel to the fuel-rich coal/air flow and participates in pulverised coal combustion during boiler operation. The method was applied to a 600 MWe down-fired boiler manufactured with the technology of Foster Wheeler Corp. Full-scale industrial measurements of furnace flue gas temperature, fuel-rich coal/air flow ignition distance, and distribution characteristics of NOx, O 2 , and CO in the furnace at loads of 200, 240, and 540 MWe were performed. The results showed that the boiler can stably operate without oil support at 240 MWe (40% rated load) and 200 MWe (33% rated load) respectively burning a blended coal of anthracite and lean coal, and blending bituminous coal. At loads of 200, 240, and 540 MWe, the fuel-rich coal/air flow ignition distances were, respectively, approximately 1.4, 1.7, and 1.3 m. NOx emissions at the furnace exit were 406, 407, and 730 mg/Nm3 (O 2 = 6%), and the boiler thermal efficiencies were 92.42%, 92.45%, and 90.58%, respectively. This novel technology presents the characteristics of high efficiency and low NOx emission while realizing low-load stable combustion of down-fired boilers. [ABSTRACT FROM AUTHOR]

A diesel generator was simulated operating with palm oil as fuel and hydrogen doping the inlet air. The objective was to investigate how the addition of hydrogen can accelerate the end of vegetable oil combustion, and consequently improve the electrical efficiency of the generator set up, for the same mass flow rate of fuel. The simulations were performed using AVL BOOST software and validated with experimental data. The generator was simulated operating with 75%, 80% and 100% of the nominal load using palm oil in nature, and hydrogen being injected at the intake manifold in parcels of 5% to a maximum of 20% in energy content by replacing the main fuel. The simulations showed increase in electrical power, reduction in specific fuel consumption, improving the overall efficiency of the generator set with 100% load. Good results were obtained with operation at 75% of the nominal load. [ABSTRACT FROM AUTHOR]

Measuring and monitoring the cylinder pressure in relation to the instantaneous cylinder volume allows the engineer to gain a great deal of information about the quality and efficiency of the energy conversion process taking place inside the cylinder. Many useful metrics can be derived or extracted from the pressure curve and these parameters are well established. This article forms the basis to propose a set of basic combustion data metrics that can be used to establish the quality of measured data. The proposed indicators can be used to establish fitness for purpose of the proposed system set-up for various measurement applications, prior to undertaking the critical measurement task. In addition, these metrics can be used or monitored during system run time, to ensure consistent data quality throughout short- or long-term test procedures, in addition to allowing identification of measurement drift or step change factors that could affect data quality over time. This article shows the application of DoE-based testing and a model-based approach in order to establish the response of newly developed metrics when stimulated with target error variations. The output could be used to understand the variation and interactions of the newly developed metrics, and also to understand if they would be usable for the application suggested. It was found that not all of the results that were tested could be utilized, but the test and measurement environment, plus the unique application of model-based testing, facilitated an efficient working environment to support future development work. [ABSTRACT FROM AUTHOR]