Showing papers in "Journal of The Energy Institute in 2018"

A review on thermo-chemical characteristics of coal/biomass co-firing in industrial furnace

Abstract: Biomass should be considered as one of the promising sources of energy for mitigating greenhouse gas (GHG) emissions Co-firing biomass with coal has become a solution for meeting the power crisis as well as to reduce the pollutant emissions The biomass fuels typically found from woody to grassy and solid recovered fuels depending on its origin and properties It is suggested that co-firing coal with biomass has a substantial effect on SO x and NO x emission level The ashing process, fly ash quality depends on the conversion technology, capture technology and the properties of the biomass In order to control the furnace efficiency and production, burnout, optimum injection of biomass sharing with specific information of particle ignition properties are also important A number of small/laboratory scale and industrial scale experiments have been conducted by different researchers Different experimental studies performed are reviewed, grouped and summarized based on the fuel processing technology, burnout performance, emission level, environmental aspect, ash information and deposit characteristics, effect of co-firing ratios and adoption of oxy-fuel co-firing Overall, this paper will highlight existing technologies and emerging trends in co-firing of different types of biomass which will be helpful for future investigations

Biodiesel production from waste cooking oil using heterogeneous catalysts and its operational characteristics on variable compression ratio CI engine

Abstract: In the present work, the optimum biodiesel conversion from waste cooking oil to biodiesel through transesterification method was investigated. The base catalyzed transesterification under different reactant proportions such as the molar ratio of alcohol to oil and mass ratio of catalyst to oil was studied for optimum production of biodiesel. The optimum condition for base catalyzed transesterification of waste cooking oil was determined to be 12:1 and 5 wt% of zinc doped calcium oxide. The fuel properties of the produced biodiesel such as the calorific value, flash point and density were examined and compared to conventional diesel. The properties of produced biodiesel and their blend for different ratios (B20, B40, B60, B80 and B100) were comparable with properties of diesel oil and ASTM biodiesel standards. Tests have been conducted on CI engine which runs at a constant speed of 1500 rpm, injection pressure of 200 bar, compression ratio 15:1 and 17.5, and varying engine load. The performance parameters include brake thermal efficiency, brake specific energy consumption and emissions parameters such as Carbon monoxide (CO), Hydrocarbon (HC), Oxides of Nitrogen (NOx) and smoke opacity varying with engine load (BP). Diesel engine's thermal performance and emission parameters such as CO, HC, and NOx on different biodiesel blends demonstrate that biodiesel produced from waste cooking oil using heterogeneous catalyst was suitable to be used as diesel oil blends and had lesser emissions as compared to conventional diesel.

Mechanism analysis on the pulverized coal combustion flame stability and NOx emission in a swirl burner with deep air staging

Abstract: Low NOx burner and air staged combustion are widely applied to control NOx emission in coal-fired power plants. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of a single low NOx swirl burner in an existing coal-fired boiler was numerically simulated to analyze the mechanisms of flame stability and in-flame NOx reduction. And the detailed NOx formation and reduction model under fuel rich conditions was employed to optimize NOx emissions for the low NOx burner with air staged combustion of different burner stoichiometric ratios. The results show that the specially-designed swirl burner structures including the pulverized coal concentrator, flame stabilizing ring and baffle plate create an ignition region of high gas temperature, proper oxygen concentration and high pulverized coal concentration near the annular recirculation zone at the burner outlet for flame stability. At the same time, the annular recirculation zone is generated between the primary and secondary air jets to promote the rapid ignition and combustion of pulverized coal particles to consume oxygen, and then a reducing region is formed as fuel-rich environment to contribute to in-flame NOX reduction. Moreover, the NOx concentration at the outlet of the combustion chamber is greatly reduced when the deep air staged combustion with the burner stoichiometric ratio of 0.75 is adopted, and the CO concentration at the outlet of the combustion chamber can be maintained simultaneously at a low level through the over-fired air injection of high velocity to enhance the mixing of the fresh air with the flue gas, which can provide the optimal solution for lower NOx emission in the existing coal-fired boilers.

In situ hydrodeoxygenation upgrading of pine sawdust bio-oil to hydrocarbon biofuel using Pd/C catalyst

Abstract: Hydrodeoxygenation (HDO) is effective for upgrading bio-oil to biofuel. However, the upgrading cost increased due to the high consumption of external hydrogen. In this paper, the hydrogen generated from cheap water using zinc hydrolysis for in situ bio-oil HDO was reported. The effect of different temperatures (200 °C, 250 °C and 300 °C) on bio-oil HDO over Pd/C catalyst was investigated in a batch reactor. The results show that 250 °C yielded biofuel with the highest heating value at 30.17 MJ/kg and the highest hydrocarbons content at 24.09%. Physicochemical properties including heating value, total acid number and chemical compositions of the produced biofuels improved significantly in comparison with that of the original bio-oil.

Investigation on ash deposition characteristics during Zhundong coal combustion

Abstract: The reserves of Zhundong (ZD) coal in China are huge. However, the high content of Na and Ca induces serious slagging and fouling problems. In this study, the ZD coal was burned in a DTF (drop tube furnace), and the ashes collected at different gas temperature with non-cooling probe were analyzed to obtain the ash particle properties and their combination mode. The results showed that Na, Ca and Fe are the main elements leading to slagging when the gas temperature is about 1000 °C during ZD coal combustion, but their mechanisms are quite different. Some sodium silicates and aluminosilicates and calcium sulfate keep molten state in the ashes collected at 1000 °C. These molten ash particles may impact and adhere on the bare tube surface, and then solidified quickly. With the growth of slag thickness, the depositing surface temperature is increased. The molten ash particles might form a layer of molten film, which could capture the other high fusion temperature particles. The Fe2O3 sphere were captured by the formed molten slag and then they blended together to form a new molten slag with lower melting temperature.

Conversions of fuel-N to NO and N2O during devolatilization and char combustion stages of a single coal particle under oxy-fuel fluidized bed conditions

Abstract: The conversions of fuel-N to NO and N2O during devolatilization and char combustion stages of a single coal particle of 7 mm in diameter were investigated in a laboratory-scale flow tube reactor under oxy-fuel fluidized bed (FB) conditions. The method of isothermal thermo-gravimetric analysis (TGA) combing with the coal properties was proposed to distinguish the devolatilization and char combustion stages of coal combustion. The results show that the char combustion stage plays a dominant role in NO and N2O emissions in oxy-fuel FB combustion. Temperature changes the trade-off between NO and N2O during the two stages. With increasing temperature, the conversion ratios of fuel-N to NO during the two stages increase, and the opposite tendencies are observed for N2O. CO2 inhibits the fuel-N conversions to NO during the two stages but promotes those to N2O. Compared with air combustion, the conversion ratios of fuel-N to NO during the two stages are lower in 21%O2/79%CO2, and those to N2O are higher. At = 21–50% by volume, the conversion ratios of fuel-N to NO during the two stages reach the maximum values at = 30% by volume, and those to N2O decrease with increasing O2 concentration. H2O suppresses the fuel-N conversions to NO and N2O during the two stages. A higher coal rank has higher total conversion ratios of fuel-N to NO and N2O. Fuel-N, volatile matter, and fixed carbon contents are the important factors on fuel-N conversions to NO and N2O during the two stages. The results benefit the understanding of NO and N2O emission mechanisms during oxy-fuel FB combustion of coal.

Experimental study on NOx emissions of pulverized bituminous coal combustion preheated by a circulating fluidized bed

Abstract: This study investigated nitrogen oxide (NOx) emissions of pulverized coal combustion preheated by a circulating fluidized bed (CFB). During the test process, high-temperature fuel preheated in a CFB was burned in a down-fired combustor (DFC). The effect of air distribution on NOx emissions was studied in the DFC, including three types of secondary air nozzle structures, five secondary air ratios, and three tertiary air position arrangements. Under stable conditions, the conversion ratio of fuel-nitrogen to N2 in the CFB was 41.4%, which resulted in lower NOx emissions in the platform. In this study, secondary air could be injected into the combustor at the top (annular) or through the side wall (circular) of the DFC, both with high combustion efficiency. This means that the secondary air is completely separated from the burner, and burner structure is greatly simplified. NOx emissions from secondary air nozzle structures of center, annular, and circular ports were 565.66, 345.45, and 220.38 mg/Nm3 (@6% O2) respectively. NOx emissions initially decreased then increased with increases in secondary air ratio with the annular nozzle structure. NOx emissions could be further inhibited by rationally arranging tertiary air positions.

Production of producer gas from sugarcane bagasse and carpentry waste and its sustainable use in a dual fuel CI engine: A performance, emission, and noise investigation

Abstract: Due to ever increasing use of conventional fuels and improper utilization of renewables, air pollution and GHG (Green House Gas) emissions are the primary areas of concern. Due to this, the world is now shifting interest towards the synthesis and use of alternate fuels; that can replace the conventional fuels. Present work focuses on an experimental investigation, which is carried out on two different biomass materials – sugarcane bagasse and carpentry waste in 1:1 ratio. Biomass samples were used to synthesize producer gas in a downdraft gasifier with a gas flow rate of 5.07 Nm3/h. Producer gas was blended with diesel and fired in a dual fuel CI engine. Engine performance was smooth while it was tested for six load variations for noise characteristics and various performance and emission parameters. A maximum reduction in diesel consumption by 45.7% and NOx emissions by 69.5% was reported with a slight increase (∼3.4 dB) in the noise.

Effects of raw material particle size on the briquetting process of rice straw

Abstract: Biomass feedstocks need to be milled or chopped into particles before briquetting, and the particle size has great effects on the energy consumption and product quality. In this study, the effects of the particle size on the rice straw briquetting process were investigated. The raw materials were milled or chopped into four different sized test materials. Experiments were carried out with an electronic universal testing machine and a self-designed single pellet unit on the basis of a simplex-centroid design. Several parameters, including briquetting time, energy consumption, maximum extrusion force, product compressive strength, and product density, were tested and recorded. The experimental data were processed by the methods of regression analysis and variance analysis. Finally, effects of raw material particle size on the briquetting process, energy consumption, maximum extrusion force, product compressive strength, and product density were obtained. Results showed that, compared with simple sized materials, mixed materials achieved lower energy consumption, higher product compressive strength, and higher product density.

Preparation and characterization of pyrolytic oil through pyrolysis of neem seed and study of performance, combustion and emission characteristics in CI engine

Abstract: This paper deals with production of pyrolytic oil from neem seed and using this pyrolytic oil in the form of blend with fossil diesel to study the performance and emission characteristics in CI engine. Thermal and catalytic pyrolysis of non edible neem seed was performed in a slow fixed bed pyrolyser to produce pyrolytic oil. Maximum pyrolytic oil obtained in thermal pyrolysis was 55% wt and in catalytic pyrolysis was 60% wt using both Al2O3 and K2CO3 catalysts followed by 41% wt and 38% wt for zeolite and kaolin catalysts respectively. The catalytic pyrolysis improved pH and calorific values of 12.4% and 14.4% respectively as compared to thermal pyrolysis. Blends of neem seed catalytic pyrolytic oil (NB) with fossil diesel in the ratio of 5% (NB5) and 10% (NB10) by volume were tested on an unmodified CI engine. Brake thermal efficiency (BTE) was lower at part load conditions and higher at full load condition up to 3.7% in the case of blends as compared to fossil diesel operation. Higher Brake Specific Fuel Consumption (BSFC) was observed in the case of NB5 blend on all load conditions, up to 23.9%. Reduction in emission levels were observed for HC (46.9%), CO (42.2%), CO2 (29.8%) and NOx (20.7%) at full load condition. This study observed that neem seed catalytic pyrolytic oil is a potential renewable and sustainable green fuel.

Experimental investigations of spray generated by a pressure swirl atomizer

Abstract: This paper has focused on the droplets behavior of kerosene RP-3 spray produced by a pressure swirl atomizers in terms of spray pattern, droplet size spatial distribution, mean droplet size, and distribution index with variations of pressure differential. The analyses have been carried out experimentally with the aid of optical diagnostic methods. The spray pattern, such as spray cone angle and fuel spatial distribution, has been measured by the technique of planar laser induced fluorescence of kerosene. A method for correction of fuel distribution measurement error induced by laser attenuation in spray is proposed and validated. The droplet size spatial distribution in central axis plane of the spray has been measured by a planar droplet sizing method which combining laser induced fluorescence and Mie scattering. The spray pattern in axial center plane and cross-sectional plane perpendicular to axis of the atomizer indicate that the droplets in spray concentrate around the outer periphery and in a narrow annular zone at the near-field of fuel injector exit, and then disperse to produce a solid spray at downstream of the spray. The analyses of droplet size spatial distribution, Sauter mean diameter, and distribution index with pressure differential clearly show the presence of droplets collision and its adverse effects on droplet size uniformity. The spray outline, droplet mass spatial distribution, and droplet size spatial distribution, droplets dispersion and collision in the process of atomization provide a great insight into the processes of atomization and spray development, which are key information for fuel injector design and quality control. The visualizations of spray pattern and droplet size spatial distribution with variations of pressure differential for pressure swirl atomizer are key issues in swirl cup or internally staged airblast fuel injectors because pressure swirl atomizer provides primary atomization or pilot spray which affects the quality of air/fuel mixing in lean-burn combustion. Moreover, a well-defined and complete database regarding the isothermal hollow cone spray is provided for validation of spray model.

Syngas production through gasification of coal water mixture and power generation on dual-fuel diesel engine

Abstract: In the present study, a syngas was produced by preparing coal water mixtures of two different concentrations and gasifying the coal water mixtures. An entrained-flow gasifier of 1 ton/day scale was used and, after undergoing a purification process, the produced syngas was applied to a modified diesel engine for power generation. As the gasification temperature increased, the carbon conversion and the cold gas efficiency were found to increase. In the composition of the produced syngas, the content of H2 remained constant, that of CO increased, and those of CO2 and CH4 decreased. The carbon conversion increased with equivalence ratio. A maximum cold gas efficiency of 66.1% was found at the equivalence ratio of 0.43. N2 was additionally supplied to verify the gasification characteristics depending on the gas feed flow rate. The optimum feed flow rate was verified at different slurry concentrations and equivalence ratio. The produced syngas was supplied to a modified diesel engine and operated depending on the syngas feed flow rate and the engine operation conditions. The brake thermal efficiency of the engine was constant regardless of the syngas feed flow rate. The diesel engine showed high efficiency despite the mixing of the syngas.

Simultaneous thermal and visual imaging of liquid water of the PEM fuel cell flow channels

Abstract: Water flooding and membrane dry-out are two major issues that could be very detrimental to the performance and/or durability of the proton exchange membrane (PEM) fuel cells. The above two phenomena are well-related to the distributions of and the interaction between the water saturation and temperature within the membrane electrode assembly (MEA). To obtain further insights into the relation between water saturation and temperature, the distributions of liquid water and temperature within a transparent PEM fuel cell have been imaged using high-resolution digital and thermal cameras. A parametric study, in which the air flow rate has been incrementally changed, has been conducted to explore the viability of the proposed experimental procedure to correlate the relation between the distribution of liquid water and temperature along the MEA of the fuel cell. The results have shown that, for the investigated fuel cell, more liquid water and more uniform temperature distribution along MEA at the cathode side are obtained as the air flow rate decreases. Further, the fuel cell performance was found to increase with decreasing air flow rate. All the above results have been discussed.

Hydrogen production by steam reforming of ethanol over Co/CeO2 catalysts: Effect of cobalt content

Abstract: The Co/CeO2 catalysts obtained by co-precipitation method were used in the steam reforming of ethanol (SRE). The influence of cobalt active phase content (15–29 wt%), the reaction temperature (420–600 °C) and H2O/EtOH molar ratio (12/1 and 6/1) were examined. The physicochemical characterization revealed that the cobalt content of the catalyst influences the metal-support interaction which results in catalyst performance in SRE process. The differences between catalytic properties of the Co/CeO2 catalysts with different metal loading in SRE process decayed at 500 °C for H2O/EtOH = 12/1. The best performance among the tested catalysts showed the 29Co/CeO2 catalyst with the highest cobalt content, exhibiting the highest ethanol conversion, selectivity to two most desirable products and the lowest selectivity to by-products in comparison with catalysts containing smaller amount of metal. Its catalytic properties results probably from its unique physicochemical properties, i.e this catalyst contains large amount of cobalt but the metal crystallites are relatively small. Regardless cobalt content, an increase in the water-to-ethanol molar ratio in the feed increased the concentration of hydrogen an carbon dioxide and decreased formation of carbon monoxide, acetone, aldehyde and ethylene.

Performance enhancement and emission reduction of used motorcycles using flexible fuel technology

Abstract: In Vietnam, the primary energy consumption has increased rapidly over the past decade, and the government promotes the vehicle emission standards and the development of renewable energy to complement fossil fuel. In concert with the government policy on these problems, motorcycle manufacturing companies have applied new technologies to reduce pollution emissions and fuel consumption. However, these technologies been applied only to new vehicles before selling on the market; as a result, they cannot solve the primary inducement due to a large quantity of used motorcycles in Vietnam. This research has developed a new fuel system that enables used gasoline motorcycles to operate on 100% ethanol, a type of renewable energy, which is widely used as a proportion in spark ignition engines. The research results showed satisfactorily that the motorcycles retrofitted the new fuel system can reduce significantly emission and fuel consumption.

The structure-reactivity relationships of using three-dimensionally ordered macroporous LaFe1−xNixO3 perovskites for chemical-looping steam methane reforming

Abstract: Chemical-looping steam methane reforming (CL-SMR) is a novel technology for syngas and hydrogen production without purification process. A series of three-dimensionally ordered macroporous (3DOM) LaFe1−xNixO3 (x = 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) perovskite-type oxides were synthesized using the polystyrene colloidal crystal templating method. The structural and physico-chemical properties of the obtained oxides were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauere-Emmette-Teller (BET) surface area technologies. The structure-reactivity relationships and effects of Ni-substitution on the improvement of reactivity and resistance to carbon formation were investigated in a thermo-gravimetric analyzer and a fixed-bed reactor. It was found that the as-prepared oxides obtained standard perovskite structures and the well-ordered skeleton was surrounded with uniform close-packed macroporous windows. Ni-substitution improved the ability for oxygen supply but simultaneously enhanced the methane dissociation. While the openness channel and large surface area of 3DOM perovskite allowed low mass-transfer resistances and provided high active sites for reaction. Complicated factors synergistically affected the reactivity and an optimal value for Ni-substitution is confirmed with x = 0.1 by comprehensively considering from the points of reactivity, resistance to carbon formation, as well as hydrogen generation capacity. During the following successive redox reactions, 3DOM LaFe0.9Ni0.1O3 exhibited good regenerability and thermo-stability probably converting 90% of CH4 into syngas in methane reforming stage and generating ∼210–220 ml hydrogen in steam splitting stage.

The impacts of compression ratio on the performance and emissions of ice powered by oxygenated fuels: A review

Abstract: Energy sources are becoming a governmental issue, with cost and stable supply as the main concern. Oxygenated fuels production is cheap, simple and eco-friendly, as a well as can be produced locally, cutting down on transportation fuel costs. Oxygenated fuels are used directly in an engine as a pure fuel, or they can be blended with fossil fuel. The most common fuels that are conceded under oxygenated fuels are ethanol, methanol, butanol Dimethyl Ether (DME), Ethyl tert-butyl ether (ETBE), Methyl tert-butyl ether (MTBE) and biodiesel that have attracted the attention of researchers. Due to the higher heat of vaporization, high octane rating, high flammability temperature, and single boiling point, the oxygenated fuels have a positive impact on the engine performance, combustion, and emissions by allowing the increase of the compression ratio. Oxygenated fuels also have a considerable oxygen content that causes clean combustion. The aim of this paper was to systematically review the impact of compression ratio (CR) on the performance, combustion and emissions of internal combustion engines (ICE) that are operated with oxygenated fuels that could potentially replace petroleum-based fuels or to improve the fuel properties. The higher octane rating of oxygenated fuels can endure higher compression ratios before an engine starts knocking, thus giving an engine the ability to deliver more power efficiently and economically. One of the more significant findings to emerge from this review study was the slight increases or decreases in power when oxygenated fuel was used at the original CR in ICE engines. Also, CO, HC, and NOx emissions decreased while the fuel consumption (FC) increased. However, at higher CR, the engine performance increased and fuel consumption decreased for both SI and CI engines. It was seen the NOx, CO and CO2 emissions of oxygenated fuels decreased with the increasing CR in the SI engine, but the HC increased. Meanwhile, in CI engine, the HC, CO and NOx decreased as the CR increased with biodiesel fuel.

NOx reduction studies on a diesel engine operating on waste plastic oil blend using selective catalytic reduction technique

Abstract: The constant escalation in the consumption of petroleum products has compelled researchers to discover for new alternative fuels which can be successfully incorporated in the existing automotive engines. Oil derived from waste plastics is one such alternative, which not only ensures longevity of fossil fuels but also assists in bringing down the hazardous impacts caused by the improper disposal of plastic wastes. This work focuses on the utilization of valuable energy of toxic non-biodegradable waste plastics to lucratively be used as an alternative fuel. An attempt was further made to reduce the NOX emissions which increased with the use of waste plastic oil blend. The main objective of this experimental investigation is to study the performance & emission characteristics of a twin cylinder CRDI engine subjected to selective catalytic reduction (SCR) after-treatment technique. Different flow rates of ammonia as a reducing agent were tested and concluded that a flow rate of 0.5 kg/hr furnishes optimum results. A comparison of NOX reduction efficiency was also made between SCR and EGR techniques. The comparison eventually indicated that SCR gives better NOX conversion efficiency at higher loads without any adverse effect on the engine performance while operating on Waste Plastic Oil blend (P30).

Characterization and performance of common alkali metals and alkaline earth metals loaded Mn/TiO2 catalysts for NOx removal with NH3

Abstract: The influence of four common alkali metals and alkaline earth metals (Na, K, Mg and Ca) on Mn/TiO2 catalysts for selective catalytic reduction of NOx with NH3 was investigated. K, Na and Ca deactivated the catalysts and the deactivation effects were shown in sequence as K > Na > Ca, while Mg improved the capability of the catalysts. Furthermore, physical and chemical properties of catalysts were characterized by XRD, H2-TPR, NH3-TPD, BET, FESEM, XPS, TG and in situ DRIFTS analyses. Characterization results suggested that the obvious decrease of NH3 adsorption and surface redox ability and the formation of inactive compounds could take credit for the deactivation caused by alkali metals and alkaline earth metals except Mg. The atomic concentrations of Mn3+ and relative concentration ratios of Oα/(Oα+Oβ) on the surfaces were also important factors for SCR activities of Mn/TiO2 catalysts doped with the main group IA elements (Na and K). The in situ DRIFTS tests further confirmed that the alkaline size resulted in the considerable changes in the desorption strength of ammonia which was in accordance with the NH3-TPD results. Meanwhile, the slight decrease of NH3 adsorption and surface redox ability and the formation of MgMn2O4 appeared to be directly correlated with the better SCR performance of the catalysts doped with Mg. Moreover, acid site and redox site played important roles in the catalytic cycle for Mn/TiO2 catalysts during the NH3-SCR reaction.

Pore structure development in Xilingol lignite under microwave irradiation

Abstract: The pore structure of Xilingol lignite irradiated by microwave was investigated to determine drying time, microwave power level, and mineral composition Pore structure was also determined using N 2 adsorption/desorption as well as scanning electric microscopy The results show that as microwave power increases from 400 W to 800 W, and irradiation time increases from 4 to 16 min, the specific surface area of lignite samples increases, average pore diameter and total pore volume decreases, and the percentage of mesopores increases The pore volumes, average pore diameters, and special surface area in the center of the lignite sample were greater than those in the outer layers, while the percentage of mesopores decreased slightly The cluster structure of the lignite samples is simpler and the surface neater, while flat and fibrous structures remain the same Evolution mechanisms for pore structures during microwave drying were similar, and include structural collapse caused by shrinkage forces resulting from the removal of moisture, the opening and crosslinking of blind and closed pores, and the thermal decomposition of organic macromolecular structures under high temperatures

3D numerical modelling of turbulent biogas combustion in a newly generated 10 KW burner

Abstract: This study concentrates on the 3D numerical modelling of combustion of different biogases in a generated burner and combustor The main goal of this study is to investigate the combustion characteristics (such as temperature and emissions) of biogases through a combustor due to depletion of natural gas Moreover, the effect of the preheated air on flame temperatures of biogases have been studied in the present study Finally, the effect of H 2 S amount in biogas on SO 2 emissions has been investigated within these predictions The numerical modelling of turbulent diffusion flames has been performed by using the standard k–e model of turbulent flow, the PDF/Mixture Fraction combustion model and P-1 radiation model in the combustor A CFD code has been used for all predictions Temperature gradients have been determined on axial and radial directions for better understanding combustion characteristics of biogases Modelling has been studied for thermal power of 10 kW and excess air ratio of λ = 12 for each biogas combustion The first finding is that combustion of biogases is possible via the newly generated burner Moreover, the results show that the one of biogas is very close to methane in terms of temperature distributions in the combustor due to including high amount of methane compared to other biogases It is also concluded that the flame temperatures of biogases increase with preheating the combustion air as expected It is finally revealed that SO 2 emissions increase as amount of H 2 S in biogas is increased through the combustor

Exhaust particle properties from a light duty diesel engine using different ash content lubricating oil

Abstract: Three kinds of lubricating oil with different ash contents were used in a light-duty diesel engine to investigate exhaust particle properties. This study applied transmission electron microscopy (TEM) equipped with energy dispersal x-ray spectroscopy (EDX). Results show that with increasing ash content in the lubricating oil, the macroscopical structure of diesel particles transforms from chain-like to a more complex and disordered agglomerated structure. The outer ordered carbon layers of the core–shell structure become thinner. The thickness of the amorphous materials attached onto the outer carbon layer increases. The mean diameter of the primary particles first increases and then decreases. The content of C element in particles decreases with increasing ash content in lubricating oil, while the content of the O element increases, as does the content of trace elements in diesel exhaust particles.

Metal-loaded polyol-montmorillonite with improved affinity towards hydrogen

Abstract: Metal-organoclays (MOC) were prepared through incorporation of Boltorn polyol dendrimer H30 in Na+-exchanged montmorillonite (NaMt), followed by in-situ dispersion of Cu0 and Pd0 nanoparticles (CuNPs and PdNPs). The organoclays displayed high CO2 retention capacity (CRC) of 3.6–11.1 μmol/g, but metal incorporation induced a significant increase of hydrogen uptake up to 51.8–508.2 micmol/g at the expense of the CRC. Thermal programmed desorption and FT-IR investigations revealed strong interactions with CO2 before metal incorporation. These interactions markedly depleted in the presence of CuNPs and PdNPs. This was regarded as a precise indicator of the appreciable metal stabilization within the organic entanglement, due to enhancements of HO:Cu0 and HO:Pd0 interactions at the expense of HO:CO2 carbonate-like association. The CO2 and H2 retention capacities (CRC and HRC, respectively) were found to strongly correlate to the number of OH groups of the dendritic moiety incorporated. Hydrogen retention appears to involve mainly physical interactions as supported by easy gas release between 20 °C and 75 °C or even at room temperature under vacuum. This demonstrates unequivocally the reversible capture of hydrogen. The increase of the hydrogen uptake with increasing contact time provides evidence of the occurrence of diffusion phenomena. This was not observed with CO2 before metal incorporation, suggesting a structure compaction that improves metal stabilization. This opens new prospects for hydrogen storage via truly reversible capture on low cost clay materials and biodegradable hyperbranched macromolecules deriving from plants.

The roles of the low molecular weight compounds in the low-temperature pyrolysis of low-rank coal

Abstract: To investigate the roles of the low molecular weight compounds (LMWCs) in the low-temperature pyrolysis of low-rank coal, Hongliulin coal (HL) was firstly thermal dissolved in n-hexane (HEX) at 260–340 °C, and the pyrolysis characteristics and product distributions of HL and its residues of thermal dissolution (RTDs) were compared. Results show that the LMWCs have a significant effect on the low-temperature pyrolysis characteristics of HL. The pyrolysis liquid (PL260-340) and gaseous product yields of RTDs, which decrease with rising TD temperature (TDT), are dramatically lower than those of HL. The total amounts of HEX soluble portion (SP) and PL at the TDT of 260 and 280 °C are essentially equal to PLHL, implying that almost all LMWCs, which with relatively low boiling point, can be directly evaporated and transferred into tar during the pyrolysis of HL. The GC/MS analysis indicates that the LMWCs contain some hydrogen-donor components (such as tetralin and indane) which can act as hydrogen donor for the stabilization of radical fragments during HL pyrolysis process.

Study on flame-vortex interaction in a spark ignition engine fueled with methane/carbon dioxide gases

Abstract: A numerical study on the in-cylinder flame-vortex interaction of gaseous spark ignited engine fueled with methane/carbon dioxide is carried out by means of large-eddy method. Evolution of in-cylinder turbulence in charge phase and flame-vortex interaction during combustion process is analyzed in great detail. It's found out that the large scale coherent structures are transformed into homogeneous small scale vortexes during the intake and compression stroke. The strong vortex cores are generated by interaction between flame and in-cylinder background turbulence. Those generated vortex cores wrinkle flame surface and augment turbulent flame speed. The contra-rotation between the two vortexes of vortex-pair in the unburned area results in the appearance of large scale flame wrinkles, which is because the vortex-pair movement leads to the local entrainment and hence stretchs of the flame surface. With the increase of volume fraction of carbon dioxide in the gases, the turbulent flame speed is decreased, the effect of vortex pair on the flame structure is weakened, and the level of the flame wrinkling is decreased correspondingly.

Effects of inlet parameters on combustion characteristics of premixed CH4/Air in micro channels

Abstract: In order to improve the stability of combustion and the working performance of the micro-combustor, this paper focuses on the effects of inlet parameters such as inlet temperature, mass flow rate and equivalence ratio. Three micro-combustors with different channel-heights are fabricated, and the three-dimensional calculation model is built to research on the combustion characteristics of premixed CH4/Air mixture. It was found that with inlet gas mixture temperature increasing, the flammability limits of the combustion under micro-scale conditions were expanded, and the channel height under which the flame can exist in the combustor reduced from 3.0 mm to 2.0 mm after preheating. On the preheating basis, increasing the equivalence ratio of the gas mixture Ф improved the intensity of gas-phase reaction due to the simulation of the important free radical like OH. Furthermore, when the inlet mass flow rate of methane m c h 4 • was increased and between m 1 c h 4 • and m 5 c h 4 • , it shows that the external wall temperature was higher in the micro-combustor of H = 2.5 mm compared with that of H = 3.0 mm. When in the micro-combustor of H = 3.0 mm, more fuel could be burned and m max c h 4 • = 2.85 × 10−6 kg/s.

Effects of fuel inlet boundary condition on aromatic species formation in coflow diffusion flames

Abstract: In a number of previous numerical studies, the fuel inlet velocity boundary conditions (BC) of coflow diffusion flames were specified at the exit of the fuel nozzle with a parabolic velocity profile. Such choices were based on the assumption that the flow inside the vertical fuel tube is fully developed and the buoyancy has negligible impact on the fuel flow at the nozzle exit. These assumptions, however, might not hold in practical experiments. This study demonstrates it is necessary to account for the effect of inlet BC location to accurately predict the nozzle exit velocity profile as well as the velocity, temperature profiles downstream, which are prerequisites for meaningful polycyclic aromatic hydrocarbon (PAH) and soot prediction in coflow diffusion flames. In particular, laboratory-scale laminar coflow diffusion flames at atmospheric pressure have been studied computationally with a focus on the effects of the fuel inlet velocity profile on PAH formation. Two sets of simulations were conducted which differ in the location specified for the fuel inlet boundary. In the first case, the fuel inlet boundary was specified at the nozzle exit while in the second case it was specified at a distance of 7 cm upstream of the nozzle exit. Parabolic velocity profiles were specified for both cases. In each set of simulations, flames with three different fuels (methane, ethylene and propane) were tested. Detailed high-temperature reaction mechanisms accounting for the formation of aromatic species were employed. The results showed that the fuel inlet BC location notably influence the predicted flow/temperature field and the resultant PAH concentration. Moreover, the effects become more notable with lower fuel stream velocities. It was also found that for propane with a density larger than air, recirculation zones were formed near the nozzle exit which exerted an additional influence on the flow development and temperature field as well as PAH formation. In addition, the effects of nozzle heating on flow development and PAH formation were also investigated.

Aerodynamic characteristics of a 350-MWe supercritical utility boiler with multi-injection and multi-staging: Effects of the inner and outer secondary air distribution in the burner

Abstract: Prior to commercial operation of the first-ever 350-MWe supercritical down-fired boiler incorporating multiple injection and multiple staging combustion technology, cold modeling experiments varying the inner-to-outer-secondary air (ISA/OSA) ratio (applying ratios of 0:10, 2:8, 5:5, 6:4 and 10:0) were performed within a 1:13 scale model of the boiler furnace. The aim of these trials was to establish an optimal inner and outer secondary air distribution model for the burner in the full-scale furnace. At ratios of 0:10 and 2:8, the fuel-rich flow apparently diffused toward the furnace center zone after leaving the corresponding nozzle outlet, resulting in the formation of relatively small recirculation zones below the arches and independent fuel-rich and fuel-lean flow streamlines. In contrast, at ISA/OSA ratios greater than or equal to 5:5, the strengthened carrying effect of the inner secondary air significantly reduced the diffusion of the fuel-rich flow. Consequently, the fuel-rich and fuel-lean flow streamlines combined in the middle region of the lower furnace and the recirculation zones under the arches enlarged. As the ISA/OSA ratio was increased from 0:10 to 10:0, the line fitting slopes for the downward airflow decay curves increased from 1.8 to 3.0, meaning that the downward airflow decayed more rapidly, such that the penetration depth was reduced. Finally, at ISA/OSA ratios of 0:10 and 2:8, the initial flow-field deflection was observed to gradually adopt a symmetrical pattern.

Experimental study of homogeneous Hg oxidation in air and oxy-simulated flue gas

Abstract: This study investigated the effects of Cl2, SO2, and NO on the mercury (Hg) speciation during oxy-combustion and compared it with the Hg speciation in air-simulated flue gas with Cl2. Experiments were conducted in a bench-scale device at 200 °C. The results of Hg oxidation in an N2 and CO2 atmosphere with Cl2 showed that CO2 indirectly restrained Hg oxidation. Oxy-simulated flue gas promoted Hg oxidation more than air-simulated flue gas promoted that, because the oxygen in oxy-simulated flue gas indirectly promoted Hg oxidation using Cl2. The percentage of Hg oxidized in both oxy-simulated flue gas and air-simulated flue gas with NO decreased as the concentration of Cl2 increased because NO restrained Hg oxidation with Cl2 through the elimination of the O and ClO radicals. SO2 inhibited Hg oxidation with Cl2 by consuming the O radicals. Moreover, when both NO and SO2 were present in oxy-simulated flue gas with Cl2, the effect of SO2 on Hg oxidation was related to the NO concentration.

A novel biomass lubricant filter and its effect on gasoline engine emissions and fuel economy

Abstract: With the increasing number of light-duty passenger car, a large amount of waste engine oil was produced yearly which has polluted the environment and wasted fossil resources. Extend engine oil drain interval and reduce its effect on engine emission is of great importance. In this paper, a kind of modified-sawdust engine oil filter was developed and the study focus on its effect on the emission characteristics and fuel consumption rate of spark ignite gasoline engine. This modified-sawdust engine oil filter was also compared with common oil filter. The tests were performed in four-cylinder direct injection gasoline engine at six different typical operating conditions. Various tests were proceed including the exhaust emissions measurement of nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbons (HC) as well as the fuel consumption rate measurement. The effect of engine oil change on engine emission and fuel consumption rate were also studied. Impurity element content of waste oil and kinetic viscosity were measured before and after modified oil filter was used. The results show that relative to common oil filter, the modified-sawdust oil filter has 0.4–2.1%, 3.7–7.5%, 1.6–13.3% decrease for CO, HC, NOx emissions, respectively. In addition, it significantly reduces oil consumption, and the three major emission species (CO, HC and NOx) was also reduced when fresh engine oil was adopted. These results indicate that the use of modified-sawdust oil filter is an effective choice to improve gasoline engine emission and fuel economy.