during pyrolysis by various techniques (Brown and Thomas, 1993; Crelling et al., 1993; Gonzáles de Andrés and Thomas, 1994; Hayhurst and Lawrence, 1995). The work of Pohl and Sarofim referred to by Hayhurst and Lawrence (1995) illustrated that the fraction offuel-N emitted during devolatilisation in a heated crucible increased with temperature: below 800 °C, less than 15% of the fuel-N left the coal; but, at around 900 °C, 40–50% of the nitrogen bound in the coal was released during devolatilization. Hayhurst and Lawrence (1995) found that the only parameter to influence the amount offuel-N released during FBC devolatilization or pyrolysis was temperature of the bed. By increasing the bed temperature from 750 to 900 °C they claimed that the fraction offuel-N released increased by 80–90%, on average.
flight mission levels. Two engine models were used; a two-spool turbofan for short-haul appli- cations and a three spool turbofan for long-haul applications. Engine design parameters were chosen to be similar to the IAE-V2500 and the Trent 700 series. The evaluation was performed by using the German Aerospace centre, DLR, performance synthesis program GTlab and an air- craft performance tool, VarMission, by the same entity. Drop-in fuels from biomass feedstock were the focus of this investigation, so the alternative fuels considered was switchgrass, forest residue obtained by Fischer-Tropsch (FT) synthesis, jatropha, camelina and algae obtained by Hydroprocessed Esters and Fatty Acids (HEFA). GTlab was then used for an evaluation of these alternative fuels, with the thermodynamic data for gas properties being derived using NASA's 7-term polynomials. The fuel model was based on , which proposed a reduced five-step fuel kinetic mechanism for jet fuel simulation. Based on this simplified fuel composition, generic fuel models were created representing Jet A-1 (JetRef) as the baseline reference, neat Syn- thetic Paraffinic Kerosene (SPK), (SPK100) and a 50/50 blend of Jet-A1 and SPK (SPK50), as two alternative fuel configurations. The fuel models were calibrated to meet the respective average hydrogen (H) mass content offuel, whereas any sulphur content within the fuel was neglected. The authors concluded that the use of alternative fuels improved fuel consumption in both operating points. For the short haul mission, defined by the authors as 860 km, using JetRef, a fuel consumption of 3654 kg was calculated. With the introduction of SPK50 and SPK100, a fuel consumption of 3620 kg and 3588 kg, respectively, was obtained, proving that the more neat the SPK blend, the more fuel efficient the engine will be. This results from the improvement of engine performance in combination with the indirect effect from a reduced take-off weight. Regarding the Emission Indices (EI) ofCO 2 , the use of SPK50 and SPK100 presented a reduction
biomass as an energy source has been utilized by techniques, such as, direct combustion, pyrolysis or fermentation for alcohol production. Until recently, there have been number of studies concerning the co-firing ofcoal/biomass blends for energy generation . Some typical biomass fuels inco-firing studies are cattle manure, sawdust, sewage sludge, wood chips, straw and refuse- derived fuels. Biomass fuels are considered
Currie, L. A., Benner, Jr. J. A. , Kessler, J. D., Klinedinst, D. B., Klouda, G. A., Marolf, J. V., Slater, J. F., Wise, S. A., Cachier, H., Cary, R., Chow, J. C., Watson, J., Druffel, E. R. M., Masiello, C. A., Eglinton, T. I., Pearson, A., Reddy, C. M., Gustafsson, O., Hartmann, P. C., Quinn, J. G., Hedges, J. I., Prentice, K. M., Kirchstetter, T. W., Novakov, T., Puxbaum, H., and Schmid, H.: A critical evaluation of interlaboratory data on total, elemental, and isotopic
was fed at the inlet to the furnace and passed through the alumina tube withcoal particles. 1 LPM carrier gas was used in the coal feeder and carried coal particles into the furnace. Another 2 LPM carrier gas was introduced into the furnace directly. In this study, the wall temperature of the alumina tube was set at 1373 K. Coal particles can be combusted com- pletely when they travel through the alumina tube. At the exit of the combustor, 5 LPM particle-free air was added as primary dilution. The diluted exhaust gas passed through a six-stage cascade impactor (Mark III, Pollution Control Sys- tem Corp., Seattle, WA) to remove particles with a diame- ter larger than 500 nm. A slip stream with low flow rate was mixed with a high flow rate (details shown in Table 1) of particle-free air to achieve a secondary dilution after the im- pactor. A SMPS was used to obtain the particle size distri- bution in the range 9−425 nm (at least 4 SMPS scans were conducted for each experimental condition). Particulate or- ganic matter was characterized by a thermal vaporization aerosol mass spectrometer (AMS, Aerodyne Research Inc.). Fine particles were also collected by quartz filters for further analysis. All experimental conditions are summarized in Ta- ble 1. Coal feed rates and gas compositions were changed in order to investigate formation mechanisms of OA during coalcombustion.
Amorphous indium-gallium-zinc oxide (a-IGZO) is the most used semiconductor in metal oxide-based thin-film transistors (TFTs) for flat-panel displays (FPDs) applications due to its superior electrical characteristics. However, its properties are not yet optimised and are far away from the intended when produced by solution, and their development is crucial to implement in plastic flexible substrates and decrease the associated costs. This work aimed to evaluate a-IGZO thin films produced by solution by varying the metallic cations molar ratio and the number of deposited layers, to apply as active channel layer in TFTs and study their performance. To make TFTs compatible with flexible substrates, the chemical method solution combustion synthesis (SCS) with urea as fuel was used to reduce the high- temperature annealing during the process. Optimised films were obtained for three-layer a-IGZO with metallic cations molar ratio ofIn 2 O 3 :Ga 2 O 3 :ZnO = 3:1:1. After this, a-IGZO
corresponding composite index, to evaluate the fire developing status, India scholar Ghosh and Banerjee (Ghosh,1967) presented the method to use C/H index to judge combustion intensity. America scholar Ann G. Kim (Ann G.Kim,2004) proposed to apply hydrocarbon index to judge the developing trend ofcoal spontaneous combustion state. Yuan S J (Yuan S J,2006) explored fire- characteristic-curve method to judge the developing trend of the fire in closed fire zone. Currently, temperature-programmed experiments and the tunnel simulation experiments are most commonly used to study the variation of indicator gases. Among them, many scholars, such as the American scholar J.B. Stott(JB Stott,1987) New Zealand researcher X.D. Cheng(X.D.Chen,1997), Turkish scholar Fehmi (Fehmi Akgün,1994), and research team from Xi'an University of science and technology (Zhong Xiaoxing ， 2009)had established successively the coal spontaneous combustion platform for the simulator investigation ofcoal spontaneous combustion process. K. Baris (K. Baris,2012) had conducted experiments for the 125g coal sample in 40, 60 and 90 degree Celsius respectively. China University of Mining and Technology (Zhong Xiaoxing,2009, Zhou Fubao, 2010) had also developed a small-sized programmed temperature experiment device to measure the coal samples under adiabatic conditions in order to understand the release regularity of indicator gases in different combustion phases. At the same time, researchers of United States, Britain, China, Japan and others had also studied the variation rules of t indictor gases through tunnel fire experiments (Kuchta J.,1982, Zhou, X,1996).
Fig. 5: Drawing of a continuous burning combustor The secondary zone begins where the injection of air through the liner holes is produced. Air and fuel flow may recirculate back into the primary zone, but largely penetrate to the combustor centerline. In addition, the temperature is lower here than at stoichiometric mixture but still too high for the turbine blades. The aim of tertiary zone is to inject extra dilution air in order to reduce the combustion exit temperature to that acceptable for the turbine inlet.
Fig. 6. Example 2-D scatterplots of the measured trace gas column amounts used to calculate emissions ratios. Data are from Fire 1, whose time-series measurements are shown in Fig. 5. Top row shows the CO vs. CO 2 data for the backfire, headfire and residual smouldering com- bustion stages of this fire. Bottom row shows the CH 4 vs. CO; CH 2 O vs. CO and NH 3 vs. CO data for the headfire stage only. The slope of the least squares linear best fit to these data (shown, along with its uncertainty) is used to derive the relevant emission ratio (ER x/y ), whose value is shown above the relevant plot. Note the different axes scales required to accommodate the varying column amounts measured during the various fires stages.
Zimmerman (1999) in his article titled ―Mobile Computing: Characteristics, Benefits, and the Mobile fra mework‖ defined mobile computing as ―the use of computing devices, which usually interact in some way with a centralised information system while away from the normal fixed workplace‖. He went on to say that, Mobile computing technology enables the mobile person to create, access, process, store and communicate information without being constrained to a single location. It is on the above basis that this researcher views mobile computing as embracing a host of portable technologies the can access internet using wireless fidelity (WIFI). These range from notebook computers to tablets, to smartphones and e-book readers. Such devices have brought about Mobile learning (m-Learning) in Zimbabwe Polytechnics, enabling staff and students to share academic resources, be able to research and develop applications from wherever they are. Zimmerman (1999) went on to identify mobile computing hardware, software and communications in use then. He identified hardware as palmtops, clamshells, handheld Pen Keys, pen slates, and laptops. The characteristics of such devices in terms of screen size was small, processing capability was limited and supported a few mobile applications. Over the years mobile devices have improved in such characteristics to make mobile computing easy, fast and user friendly. Great improvements also came with the associated systems software, with the modern devices now running on Android, Symbian and windows 8 mobile, as compared to then when MS DOS, Windows 3.1, Pen DOS were used. In communications Zimmerman talked of internet speeds in kilobytes per second (Kbps), while today’s communications devices have speeds of gigabytes per second (Gbps
The another important finding revealed by TEM was the presence of extremely small precipitates which occurred in all examined areas (Fig. 3a). The precipitates, with a diameter on the order of a few nm, gave rise to the typical type of contrast characteristic for large strain fields. The precipitates have a crystalline nature since the they showed the contrast only at certain specimen positions (specimen tilt angle) and produced some extra spots on SAD patterns (Fig. 3b). These relatively strong extra spots along with strain field contrast throughout the samples suggests fairly large volume fraction of these precipitates as well as their coherency with iron matrix. The diffuse extra spots on some diffration patterns and their proximity to the central spot may point to short ordered character of these precipitates. Though the data collected from the TEM investigation turned out to be not sufficient for identification of these precipitates, however, the occurrence of such precipitates was associated with Si content: the higher Si content the more distinct contrast in the TEM images and stronger extra spots on diffraction patterns. This observation was verified by examination of samples containing 2 to and 4.5% of Si. It can be concluded that the stronger is extra spots on diffraction patterns the higher is Rm and R o.2 and lower elongation A
Combustion experiments conducted in domestic stove burning hard coal demon- strated a predominant influence of the coal chlorine content on the PCDD/F emis- sions, together with a pronounced effect of the flue gas temperature. PCDD/F con- centrations of over 100 ng TEQ/m 3 , three orders of magnitude higher than in a modern waste incinerator, were measured in the flue gases of a domestic stove when combusting high chlorine coal (0.31%). The PCDD/F concentrations in the flue gases dropped below 0,5 ng TEQ/m 3 , when low chlorine coal (0.07%) was used. When low chlorine coal was impregnated with NaCl to obtain 0.38% chlorine content, the emission of the PCDD/F increased by two orders of magnitude. Pro- nounced non-linearity of the PCDD/F concentrations related to chlorine content in the coal was observed. The combustionof the high chlorine coal yielded PCDD/F concentrations in flue gases one order of magnitude lower in a fan cooled chimney when compared to an insulated one, thus indicating formation in the chimney. The influence of flue gas temperature on the PCDD/F emissions was less pronounced when burning low chlorine coal. The predominant pathway of the PCDD/F emis- sions is via flue gases, 99% of the TEQ in the case of the high chlorine coal for insu- lated chimney.
in the field were burnt directly to minimize the disposal cost of them. Therefore, the changing of economic situation was the primary reason for contribution changes of major subsources of biomass burning. To reduce biomass open burning emissions, a fundamental approach is to develop crop residues’ value so that people would reuse them rather than simply discard and burn them. Meanwhile, emissions from other four
From environmental, economical, and fundamental points of view fly ashes and bottom ashes from coalcombustion have been the subject of various studies with respect to their mineralogical composition, their morphology, and their carbon content [1–4]. Particularly, the latter is important, because the remaining carbon content is not only a measure for the efficiency of the combustion process, but is also a necessary parameter for further application of these ashes. Indeed, those ashes are mainly used as additives for cement and concrete and have to meet certain standards. The remaining carbon is usually measured by the loss on ignition (LOI), i.e., the relative loss of mass after heating the ash during a short period at high temperatures (750–960 °C). The LOI for fly ashes used for cement additions must be usually less than 5%, whereas fly ashes of poorer quality (>5% LOI) are then often used in the brick industry.
the ignition delay and heat release times will be much greater than the mini-mum values of 0.5 and 1 ms respectively. J. Swithenbank et al. (1996) worked on hypersonic air-breathing propulsion and his findings are chemical rearrangement time for combustion can be large at low temperature and pressures. I. N. Momtchiloff et al. (1963) worked on kinetics in hydrogen-air flow systems. And calculations of ignition delays for hypersonic ramjets and their findings are, the ignition delay length increases rapidly at the lower flight Mach numbers. Oldenborg, R.C (1989) worked on critical reaction rates in hypersonic combustion chemistry and found that High Mach number flight also results in very short residence times (millisecond time range) in a hypersonic engine which causes poor chemical combustion efficiency. S. Yungster and K. Radhakrishnan (2001) worked on simulation of unsteady hypersonic combustion around projectiles in an expansion tube and found that the flame propagation produces a series of oblique shock waves that reignite the core flow, creating an oblique detonation wave whose interaction with the laterally expanding boundary layer flame gives rise to a normal detonation wave that propagates. K. Kumaran and V. Babu (2009) worked on investigation of the effect of chemistry models on the numerical predictions of the supersonic combustionof Hydrogen. And their findings are- Multi step chemistry predicts higher and wider spread heat release than what is predicted by single step chemistry. Shigeru Aso et al. (2005) worked on fundamental study of supersonic combustionin pure air flow with use of shock tunnel and found that the increase of injection pressure generated strong bow shock, resulting in the pressure loses. The shock generator is an effective method to accelerate the combustion.
Traditionally, measures designed to reduce localized ground-level concentrations of sulfur oxides (SOx) used high- level dispersion. Although these measures reduced localized health impacts, it is now realized that sulfur compounds travel long distances in the upper atmosphere and can cause damage far from the original source. Therefore the objective must be to reduce total emissions. This paper addresses the necessary preventive measures and techniques of SOx pollution control.
Melinex samples in our laboratory. The mass of Melinex used in each experiment was corrected for the mass fraction of water (x = 0.0032), and the mass of carbon dioxide produced from the Melinex was calculated using the factor previously reported. (16) Combustion experiments were made in oxygen at p = 3.04 MPa,