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The properties of the fuels determine the quality of the combustion process and implicitly the performance of the turbojet engine. The optimal heterogeneous combustion process of an aviation fuel is ensured by a stoichiometric ratio (fuel/fuel), a combustion temperature and a maximum loading degree of the combustion chamber. The article includes a numerical analysis instrumented with Gasturb software that highlights the influence of fuel quality and combustion process characteristics of a Rolls Royce Viper turbojet engine on its performance. [ABSTRACT FROM AUTHOR]

Wheat straw, a typical agricultural solid waste, was employed to clarify the effects of torrefaction on the structural features and combustion reactivity of biomass. Two typical torrefaction temperatures (543 K and 573 K), four atmospheres (argon, 6 vol.% O2, dry flue gas and raw flue gas) were selected. The elemental distribution, compositional variation, surface physicochemical structure and combustion reactivity of each sample were identified using elemental analysis, XPS, N2 adsorption, TGA and FOW methods. Oxidative torrefaction tended to optimize the fuel quality of biomass effectively, and the enhancement of torrefaction severity improved the fuel quality of wheat straw. The O2, CO2 and H2O in flue gas could synergistically enhance the desorption of hydrophilic structures during oxidative torrefaction process, especially at high temperatures. Meanwhile, the variations in microstructure of wheat straw promoted the conversion of N-A into edge nitrogen structures (N-5 and N-6), especially N-5, which is a precursor of HCN. Additionally, mild surface oxidation tended to promote the generation of some new oxygen-containing functionalities with high reactivity on the surface of wheat straw particles after undergoing oxidative torrefaction pretreatment. Due to the removal of hemicellulose and cellulose from wheat straw particles and the generation of new functional groups on the particle surfaces, the ignition temperature of each torrefied sample expressed an increasing tendency, while the Ea clearly decreased. According to the results obtained from this research, it could be concluded that torrefaction conducted in a raw flue gas atmosphere at 573 K would improve the fuel quality and reactivity of wheat straw most significantly. [ABSTRACT FROM AUTHOR]

Fuel economy improvement and reducing exhaust emissions are drivers for advancement in engine technology and fuel quality enhancement. The latest generation diesel engine uses a high pressure common rail fuel injection system and after-treatment devices such as selective catalyst reduction (SCR) and diesel particulate filters (DPF) to meet the stringent emission norms. The performance of engine can be further improved by using better quality fuel than the minimum requirement. Fuel quality improvement can be achieved through modifying blending components and/ or using additives. This study investigates the effect of high cetane diesel on the performance and emission behavior of SCR fitted heavy-duty engines. Normal diesel is doped with diesel multi-functional additives containing cetane improver, and thereby cetane number enhanced to 55 from 52. Fuel consumption and exhaust emission were evaluated over the European stationary cycle (ESC) under the controlled test cell conditions. The fuel consumption with the high cetane diesel was 0.5% lower; CO, HC, and NOx emissions were lower by 12%, 6%, and 8% respectively over the ESC. This paper also highlights mode-wise engine performance, emissions, noise, and combustion behavior of the engine while using a cetane improver in diesel over the ESC cycle. Noise level reduced by 1 dB in the wide-open throttle performance tests when the cetane number increased by 3 units. [ABSTRACT FROM AUTHOR]

The intensification of municipal-solid-waste (MSW) production, energy usage, and the curb of the landfill have developed the need for our society to use MSW under the vision of a waste-to-energy (WTE) approach to eradicating MSW as well as to address the energy issues across the world. The WTE alteration is an environment-friendly way of disposing of MSW. This study examines the usage of plastic, wood, and paper for refuse-derived fuel (RDF) production. The RDF is solitary of MSW energy yields, whose dependability and superiority are analysed in the current work. Two different RDF have been obtained from diverse waste streams at the plant site to find the finest RDF based on energy efficiency. Plastics, wood, and paper are the principal constituents in the method of occupied RDF. The results exhibited that the RDF-PA holds a high amount of carbon as-well-as hydrogen content and a decent calorific value, which leads to better fuel quality. The retention time under combustion and pyrolysis, the volatile matter portion of RDF, has increased accordingly. As per obtained results, RDF-PA is a good option for energy applications and fuel for combustion and pyrolysis reactions. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization has been proven to improve the fuel properties of lowash straw biomass. To explore the effect of hydrothermal carbonization on high-ash straw biomass, the fuel properties and combustion behavior of hydrochar prepared by high-ash rice straw and corn straw at different temperature were studied. The results showed that increased reaction temperature could improve the C content, fixed carbon, heating value, and fuel ratios (FC/VM) in high-ash straw hydrochars, which is similar to the change trend of low-ash biomass. The hydrochar prepared at 260 °C has similar H/C and O/C atomic ratios and FC/VM to lignite. In addition, the highest energetic recovery efficiency is obtained at 200 °C. While at 180 °C, the comprehensive combustion characteristic index of the hydrochar is the best, which is 5.04 · 10-11 [min-2K-3] and 6.42 · 10-11 [min-2K-3]. In addition, the C content in the hydrochars at 180 °C was lower than the raw material, and the ash content increases with the reaction temperature, which is quite different from the low-ash biomass. In conclusion, the hydrothermal carbonization could improve the fuel quality of high-ash straw, while its ash content remains at a high level. [ABSTRACT FROM AUTHOR]

The present paper is the result of a cooperation between Politecnico di Torino and AVL List Gmbh within a recent collaborative research project funded by the EC. The research work was focused on the experimental and numerical characterization of mixture formation, combustion, and emissions in direct-injection NG engines, to draw useful indication for the design of innovative, high-performance engine concepts. As a matter of fact, direct-injection IC engines running on NG are believed to be a competitive transition solution towards a sustainable mobility scenario, given their maturity, technological readiness, and flexibility with respect to the fuel quality. Moreover, gaseous-fuel engines can further decrease their carbon footprint if blending of natural gas with hydrogen is considered. Provided that mixture formation represents a key aspect for the design of direct-injection engines, the activity presented in this paper is focused on the characterization of NG injection and on the mixing process, as well as the impact these latter hold on the combustion process as well as on engine-out emissions. The mixture formation process was analyzed by means of combined CFD and optical investigations. Furthermore, a full version of the engine was tested on a dynamic test rig, providing quantitative information on the engine performance and emission characteristics. The CFD results highlighted the correlation between the mixture homogeneity and the combustion stability and hinted at a relevant impact of the jet characteristics on the air charge tumble and turbulence characteristics. [ABSTRACT FROM AUTHOR]

The utilisation of waste wood from furniture production brings new problems connected with an incomplete thermochemical decomposition of additives (chemicals for improving properties of plastics) in small heating with the addition of sources. Unique organic compounds produced by the combustion of waste wood allow the identification of the type of fuel. The organic compounds contained in the char deposits were analysed by pyrolysis gas chromatography with mass spectrometry. The deposits from the combustion of briquettes from furniture production contain organic compounds originating by decomposition of phenolic resins, aminoplasts (urea–formaldehyde, resorcinol–formaldehyde and melamine), polyurethanes and wood glue. Additives contained in the deposits include plasticisers such as phthalates (DEHP, dibutyl phthalate and diisobutyl phthalate), flame retardants (2-propanol, 1-chlorophosphate (3:1) and p-terphenyl). Deposits from the combustion of briquettes from virgin wood do not contain these compounds. The total amount of compounds identified in the deposits from the boiler, which do not come from virgin wood combustion, varies in the range between 4.25 and 6.25 g/kg. Phthalates (55.5%) and PVAc adhesives (18.6%) are the main anthropogenic compounds in the deposits from domestic boilers. [ABSTRACT FROM AUTHOR]

Fuel quality especially biodiesel is highly dependent to its water content and the major sources of water in the fuels relates to the transportation, production, and storage process. In this present contribution, a complete explanation of a powerful PSO algorithm coupled with ANFIS strategy was utilized to account the water content of biodiesel and diesel mixtures based on temperature and composition. Modeling results indicate that predicted values of water content are in good agreement with extracted experimental datasets. Also, accuracy and robustness of ANFIS-PSO strategy used for the prediction of water content of biodiesel and diesel mixture is comprehensible from comparing modeling results with experimental measurements. Therefore, ANFIS strategy can be employed as an assistive lever for engineers in the bio refineries for the prediction of the water content of the diesel and biodiesel blend at the production, transportation and storage process of biodiesel. Moreover, modeling results illustrates that the enviromental effect of biodiesel and produced undesierd product after biodiesel combustion is predictable using ANFIS modeling. [ABSTRACT FROM AUTHOR]

Low energy density and low ash melting temperatures of agro-industrial waste biomass are bottlenecks for their sustainable use in combustion utilities. Torrefaction at low temperature (350 °C for 30 min) for energy density enhancement followed by very simple aqua-washing technique to remove soluble mineral matters from biochar (BC) samples have been employed in this research work to investigate possible improvement of combustion performance of tobacco stalk (TS), sugarcane bagasse (SB), and poultry litter (PL) biomasses (BM). Though the energy density of the BC was significantly higher than their respective BM, the propensity for slagging was also higher, particularly in TS-BC and PL-BC. On char washing, ash content as well as the slagging and fouling tendencies were estimated to be decreased. Energy densification ratio (as compared to biomass) as well as GCV were further increased in washed biochar (WBC). As per the DSC-TGA investigations, combustion reactivity of BC was improved by washing. The significant advantages of BC washing were observed in TS-BC and PL-BC due to the removal of a large amount of soluble materials from respective BCs. As the water extracted material from SB-BC is insignificant, unwashed SB-BC having sufficiently high GCV (20.6 MJ/kg), energy densification ratio (1.5), carbon content (66.7%) can be directly used without washing. Water washing of BC is highly beneficial for TS and PL in respect of combustion performance and a valuable potassium-rich fertilizer material was obtained on evaporation of the leachate depicting unique value-addition of entire process. • Agro-industrial waste biomass torrefied and resultant char washed to improve fuel quality. • Combustion behavior of tobacco, bagasse and poultry litter improved by torrefaction. • Biochar washing decreased slagging propensity of tobacco and poultry litter. • Bagasse char could be used directly without char washing. • Washed leachate evaporated to potassium rich salt, a valuable fertilizer material. [ABSTRACT FROM AUTHOR]

Particulate matter emissions (PM 10) from the combustion, in a residential stove, of two commercial brands of certified (ENplus A1) pellets, a non-certified brand and laboratory made pellets of acacia were tested for their ability to induce ecotoxic, cytotoxic, and mutagenic responses in unicellular organisms and a human cell line. Ecotoxicity was evaluated through the Vibrio fischeri bioluminescence inhibition assay. Moreover, cytotoxicity was assessed at two time points (24- and 48-hr) through two complementary techniques in order to evaluate the cellular metabolic activity and membrane integrity of human lung epithelial cells A549. The Ames test using two Salmonella typhimurium strains (TA100 and TA98) was employed to assess the mutagenic potential of the polycyclic aromatic hydrocarbon fraction extracted from the PM 10 samples. Results obtained with the bioluminescent bacteria indicated that only particles from the combustion of acacia pellets were toxic. All samples induced impairment on the A549 cells metabolic activity, while no significant release of lactate dehydrogenase was recorded. PM 10 emissions from acacia pellets were the most cytotoxic, while samples from both certified pellets evoked significant cytotoxicity at lower doses. Cytotoxicity time-dependency was only observed for PM 10 from the combustion of acacia pellets and one of the brands of certified pellets. Mutagenic activity was not detected in both S. typhimurium strains. This study emphasises the role of the raw material for pellet manufacturing on the toxicological profile of PM emissions. Alternative raw materials should be deeply investigated before their use in pelletisation and combustion in residential appliances. [Display omitted] [ABSTRACT FROM AUTHOR]

The large scale utilization of agricultural biomass as fuel is restricted by the feedstock properties of low energy density, high moisture content, heterogeneous composition and chemical impurities. In this work, torrefaction of biomass fuel with NH 4 H 2 PO 4 additive was carried out to investigate the effects of NH 4 H 2 PO 4 mixing ratio and torrefaction temperature on the properties of the torrefied fuel and particulate matter (PM) emission characteristics from combustion. The results show many benefits from NH 4 H 2 PO 4 addition in biomass feedstock: 1) the removal of O and retention of C can be enhanced leading to lower mass and energy losses during torrefaction, 2) more Cl and S are released to gas phase leading to a lower absolute content of Cl and S in the torrefied fuel, and 3) the occurrence of alkali and alkaline earth metals change significantly. Moreover, the emissions of the fine particulate matters (PM 1) from the torrefied fuels are clearly reduced when NH 4 H 2 PO 4 is added and the reduction rate is closely related to P/K molar ratio with the maximum reduction rate achieved at P/K molar ratio equal to 1. These results suggest that the proposed method can effectively upgrade the fuel qualities and reduce PM 1 emissions from the fuel combustion. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: The dependence on petroleum has been escalating owing to the proliferation of energy demands and population. Environmental degradation and depletion of petroleum resources are motivated to search the clean energy fuels for diesel engines. Recent studies have been advocated biodiesel as a strong contender to diesel fuel for diesel engines. Despite the significant development in the biodiesel field, there are still issues related to the usage of biodiesel in diesel engines. To overcome these issues, n‐butanol is identified as a biofuel additive that can improve the properties of biodiesel and its blends. The objective of this review is to compare the effect of the butanol–biodiesel (Bu/B), butanol‐biodiesel‐diesel (Bu/B/D), and biodiesel‐diesel (B/D) blends on the performance, combustion, and emission characteristics of diesel engines. Performance characteristics for Bu/B/D blends were observed remarkable than Bu/B and B/D blends, however, slightly inferior to diesel fuel. Combustion parameters of Bu/B/D blends were analogous to B/D blends however superior to Bu/B. Emission characteristics were reduced to a great extent with Bu/B/D blends as compared to all other sample fuels. This article also analyses the overview of biobutanol production from lignocellulosic biomass by acetone‐butanol‐ethanol fermentation process. Finally, this study reports that butanol has the potential, which can help to sustain engine performance and mitigate emissions. Among all the Bu/B, Bu/B/D, and B/D blends, Bu/B/D blends provide better fuel quality and significant results from the diesel engine characteristics; however, up to 20% blending of butanol with B/D blends showed better results after that engine performance decreased. [ABSTRACT FROM AUTHOR]

Currently, the vehicle industry is confronted with issues such as the depletion of fossil resources, an increase in crude oil costs, and stricter emission regulatory standards. In this scenario, the use of viable alternatives to diesel as a fuel is necessary. This study discusses the combined effects of injection time and exhaust gas recirculation (EGR) on neat algal biodiesel-powered diesel engines. The transesterification technique was used to extract algal oil methyl ester (AOME), and the majority of the fuel qualities of AOME were quite comparable to diesel. The practicality of neat AOME for diesel engines operating at varied injection timings such as 19º BTDC, 23º BTDC, and 27º BTDC was investigated. The results of the tests revealed that advanced injection timing has a 3.02% higher BTE than standard fuel injection timing at maximum load for the AOME. Compared to other injection timings at full load, the neat AOME at 27º BTDC has better combustion characteristics and lower exhaust emissions. At full load, however, NOx emissions were higher. NOx emission was reduced by 35.24% when AOME was burned at 27º BTDC combined with 10% exhaust gas recirculation (EGR) compared to 27º BTDC without EGR. [ABSTRACT FROM AUTHOR]

The study investigates the impact of decomposition processes of beech and pine wood on the fuel quality and the combustion chemistry in a wood‐burning stove. Especially, when considering the volume of wood fed, the burning time and energy output decrease with the stage of decomposition. The gaseous emissions as well as the total dust emissions do not change, depending on the decomposition processes. However, at the experiments carried out here, the combustion of softwood generally showed lower gaseous emissions than hardwood. [ABSTRACT FROM AUTHOR]

The process of burning the coal particle is a complex process that depends on a multitude of factors: coal composition, coal moisture, fineness of grinding, type of combustion plant, combustion air temperature, combustion air distribution, outbreak temperature. Therefore, in this paper was made a study of the parameters that influence the quality of the fuel used in the combustion process. [ABSTRACT FROM AUTHOR]

• The effects of waste tyre pyrolysis oil on the diesel engine, in conjunction with hydrogen, have been thoroughly examined. • Increasing the concentration of waste tyre blends reduces engine torque significantly. • Inclusion of hydrogen enhances the brake power irrespective of the engine speed. • At a wide range of speeds, significant reductions in CO, CO2, and NOx emissions were observed. The increasing global demand for alternative fuels as a replacement for fossil fuels has sparked a surge in the use of non-fossil fuel sources. While many alternative fuels already offer improved performance characteristics, ongoing research seeks to further enhance their quality. This particular study focuses on elevating fuel quality by introducing hydrogen into waste tire pyrolysis oil. To conduct the investigation, experimental tests were performed using three different fuel combinations: standard diesel, 15% (W15) waste tire pyrolysis oil blends, and 30% (W30) biodiesel blends. Additionally, each of these blends was enriched with 5 L/min of hydrogen gas. The experiments were conducted in a naturally aspirated, direct injection, four-cylinder, inline, four-stroke diesel engine, operating at various speeds of 1000 rpm, 1500 rpm, 2000 rpm, and 2500 rpm. The study assessed the parameters such as torque, power, specific fuel consumption, carbon monoxide, carbon dioxide, and nitrogen oxide emissions. Furthermore, this research explored the viability of utilizing waste tire pyrolysis oil blends with hydrogen as fuel in compression ignition engines without any modifications, as their fuel qualities were observed to be comparable to standard diesel fuel. Encouragingly, the results indicated that the addition of hydrogen to waste tire pyrolysis biodiesel improved the combustion process and led to a reduction in harmful gas emissions. Despite waste tyre pyrolysis oil possessing a lower heating value in comparison to diesel, the findings revealed that this heating value could be effectively enhanced by introducing hydrogen through the engine's inlet manifold. Among the blends tested, W15 emerged as a particularly promising alternative fuel for diesel engines due to its favorable performance and reduced environmental impact, as evidenced by lower carbon monoxide, carbon dioxide, and nitrogen dioxide emissions. [ABSTRACT FROM AUTHOR]

Different streams of low-grade biomass of different origins (road side grass, miscanthus, wheat straw and spruce bark) were upgraded to reasonable quality commodity fuels by significantly reducing the alkali and chlorine content, through washing with water in a first step and torrefaction in a second. The aim was to produce a cleaner fuel with a higher energy content for further densification. The final goal was to demonstrate the improvements attained by the upgrading process during combustion using the lab-scale combustion simulator facility of ECN part of TNO. Analyses of the original, washed and washed/torrefied samples showed that approximately 90% of Cl and up to 60–80% of K can be removed by this upgrading route; during the torrefaction step Cl and S are removed from the solids; during torrefaction K and Na are not significantly altered; the pre-wash step is crucial for the removal of K. Si and Ca remain largely in the solid fraction; post-wash seems to be a viable route to upgrade dry-type of biomasses; "straw" like material requires more time for washing than "grass" type. The combustion results showed that: NOx emissions are generally decreased after upgrading; High temperature chlorine corrosion can be effectively mitigated; Fine particulate matter (submicron/aerosols) formation is strongly reduced, effectively reducing the risk of alkali induced fouling. However, slagging tests revealed that pre-washing and torrefaction has minor impact on the slagging propensity of the fuel. Only, slightly reduced slagging is observable and therefore the use of mineral combustion additives, or smart blending with other fuels in order to further mitigate the slagging risks is strongly recommended. [ABSTRACT FROM AUTHOR]

Biodiesel can be fueled in compression ignition (CI) engine to substitute fossil diesel. However, the substitution of biodiesel in CI engine can increase the emissions of CO, NOx, HC and smoke. In the present study, the consequences of biodiesel addition, SOI timing and number of fuel injections on engine out responses of the diesel engine are investigated. Variation of the start of injection (SOI) timing and a number of fuel injections using 20% and 50% of biodiesel mixing ratios were carried out at a constant speed and load. The results showed that a significantly lower NOx level can be attained by retarding SOI timing for both of the biodiesel blended fuels and with a higher number of injection pulse. Interestingly, with B50 fuel operation, the concurrent decrement of NOx and smoke by an average of 12% and 37%, respectively, in comparison to the corresponding baseline diesel can be attained with late SOI and triple injection strategy. With optimum SOI timing setting, the splitting of fuel injection into multiple events can be used to address NOx-smoke trade-off in a CI engine in conjunction with the operation of biodiesel fuel. [ABSTRACT FROM AUTHOR]

The article deals with verification of a diesel fuel and two fuel mixtures blends with different amounts of the bio-component using the model single-cylinder engine without the additional equipment for treatment of exhaust gases. This combustion diesel engine served for measuring the performance characteristics of the model single-cylinder engine and the individual emission components in order to assess the use of these blends of liquid paraffinic diesel fuel in practice and to meet current and forthcoming European legislation and to fulfil the commitments by 2020. A detailed chemical analysis was performed in case of all the tested paraffinic diesel fuels. [ABSTRACT FROM AUTHOR]

A thermal power plant plays an important role for generating the electricity. The thermal power plants require essential elements, which are fossil fuels, such as coal, oil, etc. Coal is burned to generate heat energy in the furnace. Hence, analysis of flame is very important when fuel combustion takes place in a furnace. Combustion quality plays an important role to reduce the wastage of fuel. The combustion quality of fuel is high and has the less wastage of fuel. As fossil fuels are more expensive in cost, Flame image monitoring system plays an important role in analysing the combustion quality. Flame image monitoring system involves capturing the flame image in different instants of time to check the quality of combustion with the help of Back Propagation Algorithm (BPA) and Ant Colony Optimization (ACO) technique (Sujatha et al., 2017). The quality of combustion also depends on the flame temperature. The intelligent sensors are used to monitor the flame temperature and Internet of things (IoT) is used to make the flame monitoring system smarter. [ABSTRACT FROM AUTHOR]

• Karanja biodiesel blends has been tested with hydrogen in the diesel engine. • 10% and 20% blends with hydrogen have been examined for combustion duration and mass fraction burnt. • Combustion duration has been decreased for the biodiesel blends. • Karanja biodiesel increased the total accumulation of NOx due to cylinder temperatures. Although the combustion of petroleum-based fuels currently satisfies the majority of our energy needs, rapid industrialization has spurred the utilization of alternative energy sources to meet the growing demand for electricity. With the global population on the rise and increasing awareness of the dangers of climate change, there is a greater need to find sustainable and eco-friendly fuels. Utilizing biodiesel derived from non-edible sources is the most efficient and appealing option for meeting energy needs while mitigating environmental impacts. This paper focuses on the preparation and experimental analysis of biodiesel from Karanja oil. Various blends of Karanja biodiesel and regular diesel were produced and stirred to create KB10 (Diesel 90% + Karanja Biodiesel 10%) and KB20 (Diesel 80 % + Karanja Biodiesel 20%). Hydrogen was incorporated into the biodiesel to enhance fuel characteristics, delivered at a rate of 5 L per minute. The emissions and combustion results of the biodiesel blends were compared to those of pure diesel. At full load condition, KB10H5 reported the minimum combustion duration of 25.8°CA with mass fraction burnt of 17.8%. However, the biodiesel blend with 10% and 20% reported the reduced BTE. Highest brake power has been observed at 4.95 kW. The combination of Karanja biodiesel and hydrogen improves fuel quality and reduces the harmful gases emissions such as carbon monoxide and carbon dioxide. It is crucial to ensure that the operation is both efficient and comfortable, and this approach achieved both objectives. In addition, hydrogen energy can also be applied to the railway transportation industry, as a new direction for the green and low-carbon development of intercity transportation, driving the virtuous cycle and innovative development of the hydrogen energy-related industrial chain. [ABSTRACT FROM AUTHOR]

The thermal transportation of pulverized semi-coke is a critical link of pulverized coal pyrolysis and downstream application technology. In this work, the semi-coke powder stably produced in an industrial test device was used as the raw material, and the properties and influencing factors during thermal transportation process were researched. In comparison with feed coal, the total moisture of semi-coke decreased to 1.5%, the calorific value increased to 29.80MJ/kg, and the combustion performance parameters were similar, which made it a high quality fuel. The characterization results indicated that the surface of semi-coke was attached by a large amount of volatile matter, and it had a similar particle size and a more concentrated distribution, as well as higher degree of aromatization. The thermo gravimetric analysis and tube furnace test presented that the oxidative combustion intensity of semi-coke increased with the growth of specific contact area, temperature and oxygen concentration. Pulverized semi-coke started oxidative combustion above 350 °C at air atmosphere, and at a constant temperature of 350 °C, significant oxidative combustion occurred when the oxygen concentration exceeded 10%. • Thermal transportation of pulverized semi-coke is significant in engineering. • Raw material: pulverized semi-coke stably produced from an industrial test device. • Structural properties of the pulverized semi-coke were studied. • TGA and tube furnace tests were conducted to study the thermal transportation process. • Pulverized semi-coke starts oxidative combustion above 350 °C at air atmosphere. [ABSTRACT FROM AUTHOR]

• The ability of OI to characterize fuel's reactivity for LTGC was investigated. • Experiments show that the correlation between OI and LTGC reactivity is poor. • Lean operation is responsible for poor OI performance at beyond MON. • K values inconsistent with OI theory are obtained under realistic LTGC conditions. This work analyzes the inability of the Octane Index (OI) to characterize the autoignition resistance of gasoline-like fuels in a Low-Temperature Gasoline Combustion (LTGC) engine. Experimental studies in the Sandia LTGC engine at naturally aspirated 'beyond-MON' and high-boost 'beyond-RON' conditions showed a poor correlation between OI and autoignition reactivity. These experiments were successfully replicated in CHEMKIN, allowing detailed studies of the factors affecting the OI correlation. Systematic investigations were conducted to determine why the OI performs less well for LTGC combustion compared to end-gas autoignition (i.e. knock) in spark-ignition (SI) engines. A pseudo-MON condition that follows the pressure–temperature (P-T) trajectory of the real MON test was tested numerically, using 10 different fuels, leading to the conclusion that the OI correlation performs very well for an SI engine running at close-to-MON conditions. The effects of each difference between SI and LTGC combustion were then analyzed for four P-T trajectories: 'beyond-MON', 'MON test', 'between RON-MON', and 'beyond-RON' conditions. These differences included changes in: equivalence ratio, engine speed, and residence-time history along the P-T trajectory for piston-only compression, as used for LTGC, compared to compression by the piston plus flame propagation for SI combustion. For LTGC combustion, the OI correlation did not characterize the autoignition quality of gasoline-like fuels well for any P-T trajectory, but the factors causing this poor performance varied with conditions. For example, at naturally aspirated LTGC conditions (beyond-MON), changes in equivalence ratio were the primary cause, followed by differences in the P-T trajectory and changes in residence time. Whereas, for intake-boosted beyond-RON conditions, differences in the P-T trajectory had the largest effect, followed by changes in residence time. Finally, the parameter K that characterizes the OI correlation showed values that contradict the OI theory under realistic LTGC conditions, suggesting that K might be meaningless for LTGC engines. [ABSTRACT FROM AUTHOR]

Researchers all around the world are making strenuous efforts to find alternative fuel to ameliorate the problem of depletion of fossil fuel. we have identified a novel plant based biofuel, namely Cymbopogon flexuous biofuel. It has excellent fuel properties and is widely available in India and it seems to have the potential to make India self-sufficient in energy production. Cerium oxide nanoparticles were synthesized using sol–gel combustion methods. Their structural, morphological and elemental properties were studied with the help of XRD, SEM, TEM and EDS respectively. On volume basis, 20% raw Cymbopogon flexuous biofuel was blended with diesel fuel, and various proportions of Cerium oxide nanoparticles, namely C20-D80 + 10 ppm, C20-D80 + 20 ppm andC20-D80 + 30 ppm were prepared. The properties like density, kinematic viscosity, calorific value of the test fuel were measured as per ASTM standards and compared with those of diesel fuel. An experimental study of its performance, emission, and combustion behavior was conducted at varied load conditions at a constant speed of 1500 rpm. NO x and smoke emission was simultaneously reduced by 3% and 6.6% respectively as compared with biofuel blend. Due to higher thermal stability and oxygen buffer of Cerium oxide nanoparticle the brake thermal efficiency was higher by 4.76% and cylinder pressure and heat release rate was also higher. [ABSTRACT FROM AUTHOR]

To study the influence of fuel temperature on performances of biodiesel engine, combustion and emission performances of biodiesel engine at different fuel temperatures are tested and studied. It is found with the increase of fuel temperature, combustion pressure and instantaneous heat release rate curves leave far away from the top dead center and at high loads the combustion delays obviously; peak combustion pressure and peak instantaneous heat release rate decrease and at high loads the reduction increases; the backward combustion increases; at 1500 r/min, compared with 25 °C, NO X emissions of biodiesel at 40 °C and 55 °C averagely decrease by 7.6% and 9.1%, but smoke emissions averagely increase by 29.1% and 54.1%. Results indicate that fuel temperature has important influence on performances of biodiesel and it can be selected as a basic parameter to control the combustion and emission of biodiesel. [ABSTRACT FROM AUTHOR]

The sulfur behaviors of coal pyrolysis and combustion in air and oxy-fuel circulating fluidized bed (CFB) conditions showed that during coal pyrolysis, a significant increase of weight loss and CO emission were presented in CO 2 atmosphere at temperature above 900 K, then the increase of CO emission promoted the transformation of H 2 S and other sulfur compounds to COS, and led more SO 2 emission by reduction of CaSO 4 . The main sulfur-containing gas changed from H 2 S in N 2 atmosphere to COS in CO 2 atmosphere. In oxy-fuel combustion, less SO 2 , more H 2 S and COS released compared with those in air combustion, the SO 2 became the main sulfur-containing gas. With the O 2 concentration increasing, more SO 2 , COS and H 2 S released at lower temperature by faster burning. As the particle size and heating rate increasing, the SO 2 and H 2 S emission increased, and the COS emission decreased. Finally the comprehensive characteristics of sulfur behavior were proposed. [ABSTRACT FROM AUTHOR]

Urban biomass from green areas is a potential resource for bioenergy recovery, which is widely unused. Different types of organic material (e.g., grass, leaf litter) usually occur in mixtures due to common collecting practice. Forty samples of grass, leaf litter (genera: Acer, Quercus, Tilia), and mixtures of both, containing one third grass or leaf litter, were investigated to evaluate the effect of the 'Integrated Generation of Solid Fuel and Biogas from Biomass' (IFBB) on material and energy fluxes as well as relevant characteristics of resulting energy carriers. IFBB divides biomass into a fiber-rich press cake and a highly digestible press fluid by mashing with subsequent pressing. Ensiling of samples was successful with pH values ranging from 4.2 in grass to 4.8 in pure Tilia samples. Concentration of most minerals with exception of Ca and Mg were higher in grass than in leaf litter silage. The IFBB treatment reduced the element concentration in the press cake independently from the substrate. Linear regression models revealed high influence of the initial concentration in silage on the concentration in the press cake. The lower heating value of the press cake was nearly constant (19 MJ kg DM) independent from mixture. Methane yields from press fluid digestion ranged from 172 (mean of leaf litter samples) to 325 l kg VS (mixture of 33 % leaf litter-66 % grass). For an evaluation of the economic and ecological potential, models of the spatial and temporal occurrence of these biomasses need to be established. [ABSTRACT FROM AUTHOR]

In the present study, hydrochar/lignite pellets were prepared and their fuel qualities including tensile strength, combustion characteristics and ash-related problems were investigated. The results showed that addition of hydrochar to lignite increased tensile strengths of lignite pellets, especially when the hydrochar fraction exceeded 50% in the blends. The main binding forces within hydrochar/lignite pellets were similar to those of hydrochar pellets; the lignite particles were merely interlocked within the matrix of the hydrochar structure. Obvious interactions were observed between hydrochar and lignite during blend pellet combustion and as a result, enhanced thermal efficiency and decreased air pollutant emissions were expected during hydrochar/lignite pellet combustion compared to lignite pellet combustion. The ash from hydrochar/lignite pellets had similar chemical composition to that from lignite pellets, indicating that the utilization and disposal of blend pellet ash would be similar to lignite pellet ash. Furthermore, hydrochar addition to lignite decreased slagging inclination of blended pellets. Based upon calculated slagging index (SI) values, ash from hydrochar/lignite blend pellets was within a low slagging inclination range when the hydrochar fraction in the blend pellets was higher than 50%. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present one of the ways to resolve the difficulties encountered during the use of the classical process control. The article presents the problem of a dynamically changing quality of fuel delivered to the water- grate boiler type WR-25, in which the combustion process takes place. The method of the measurement process variables related to this process was described. In the next part of the article, the author presents the basic concepts related to the natural immune system, and also introduces the scheme, ideas and a negative selection algorithm. Also, the conditions were presented in which the proposed algorithm performs a detection of anomalies in the regulation burned. The solution of the problem and the results of the proposed solution where presented in the final section of the article. [ABSTRACT FROM AUTHOR]

The article presents the problem of dynamically changing fuel quality during the control of combustion process. The way of the measurement process variables related with this process was described. In the next part of the article schematics, ideas and genetic algorithm were presented by the author. They are also presented conditions in which the above anomaly detection algorithm perform in the regulation of combustion. The results of these solution were presented in the final section. [ABSTRACT FROM AUTHOR]

An experimental study on the ignition and combustion of diesel-type sprays using n -heptane, iso -octane and four intermediate blends is presented. The choice of components was done in order to represent the transition from conventional diesel fuel ( n -heptane) to a gasoline-like one ( iso -octane) in terms of ignition behavior. The experiments have been carried out in a high pressure high temperature vessel using specifications from the Engine Combustion Network (ECN). Parametric variations of oxygen concentration and air temperature have been performed for each fuel. In order to investigate the spray development, schlieren imaging for the quantification of spray penetration and ignition delay, OH ∗ chemiluminescence imaging for the lift-off length, and broadband radiation imaging for the soot intensity and flame length have been applied. The results show the large effect of mixture reactivity on the ignition times and lift-off length values. Regarding the effect of the octane number of the blends on the ignition delay times, a linear effect has been found in the lower half of the blend range, while an exponential trend is evident in the top one. On the other hand, a scaling law for the stabilized flame length based upon momentum-controlled assumptions has shown that results are comparable to those obtained in the literature. Finally, the applicability of the results obtained on the performance and efficiency in real engines is discussed. [ABSTRACT FROM AUTHOR]

Pure, blended and additivated biomass pellets from four fen paludicultures were produced at TFZ and combusted in two small-scale biomass boilers (15 kW, 30 kW). Feedstocks derived from straw of Typha ssp., Phragmites australis , Phalaris arundinacea and Carex ssp. that were harvested during winter 2018, 2019 (used for pelletization) and 2020. Additivation of fuels with kaolin before pelletization or blending of fuels with EN plus wood pellets (A1 quality) after pelletization were applied. Straw and pellets were analyzed for physical and chemical fuel properties according to international standards for solid biofuels. Physical properties of pellets met the requirements of ISO 17225–6. Chemical properties of Typha indicated high TPM emissions due to high contents of K and Na in fuels while severe slagging was predicted for the other species by a high molar (Si + K + Al)/(Ca + Mg + P) ratio. During combustion in both boilers, CO and total particulate matter (TPM) emissions were high for Typha but slightly reduced by additivation with 2.3% kaolin. Blending of fuels significantly reduced NO X , SO X and HCl emissions due to lower N, S and Cl concentrations. Slagging was high for pure and additivated pellets of Phragmites , Phalaris and Carex with >50% of total ash consisting of particles >2 mm. No steady-state boiler operation could be achieved with either pure or additivated fuels. In conclusion, paludiculture pellets are challenging fuels for small-scale combustion plants. Their use cannot be recommended for the tested boilers. Technical solutions may be easier applied in medium sized combustions plants above 100 kW. • Fuel quality and combustion behaviour of paludiculture straw & pellets were analyzed. • Additivation (kaolin) and blending (wood) were applied to improve combustion. • CO & TPM emissions were high for Typha while slagging was high for all other fuels. • NO X emissions were significantly increased for paludicultures but improved by blending. • Kaolin had only minor effects on combustion due to overall low additivation levels. [ABSTRACT FROM AUTHOR]

This paper analyzes the performance and emissions of biodiesel from different feedstocks. The main goal of this paper is to provide information to the engineers, industrialists and researchers who are interested on biodiesel and to emphasise biodiesel as a promising alternative replacement for fossil fuels. A substantial number of literatures from highly rated journals in scientific indexes were cited preferentially since 2000. The performance and emissions indicators such as brake torque, brake power, BTE, EGT, BSFC NO x , PM, CO, CO 2 , HC and smoke density have been evaluated in comparison to pure diesel. The results showed that different sources of biodiesel feedstocks give different results to engine performance and emissions. Surprisingly some of the research yielded favourable results towards the biodiesel as compared to pure diesel. The study concluded that biodiesel can be used in compression ignition engine as a replacement of diesel fuel to fulfil the global energy demand. However, further research on about optimisation, cost-effectiveness and availability of biodiesel needs to be carried out to help ensure that biofuel will be able to fully replace fossil fuel. [ABSTRACT FROM AUTHOR]

Low temperature pyrolysis was employed to produce solid fuel biochars from woody (pine wood) and non-woody biomass (coconut fiber) in the present study. Chemical evolution of biomass under pyrolysis conditions was determined and fuel qualities of the biochars were evaluated including energy densities, ash-related problems and combustion behaviors. The results showed that dehydration reaction of the biomass had same preference with decarboxylation reaction under pyrolysis conditions. The hemicellulose and cellulose in non-woody biomass showed faster decomposition than those in woody biomass. The biochars derived from coconut fiber showed lower energy densities and energy yields than those from pine wood under identical conditions. All major ash forming metals originally contained in raw biomass were accumulated in the resultant biochars and more serious slagging and fouling problems were present during combustion of pyrolytic biochars compared to raw biomass. The reactivity of biomass decreased and the main mass loss shifted to elevated temperature zone with the increasing pyrolysis temperature, indicating increased thermal efficiency and environmental benefits were achievable during biochar combustion compared to raw biomass combustion. Taking into account combustion characteristics and energy yield, optimal pyrolysis temperatures for solid fuel production were around 300 °C for coconut fiber and 330 °C for pine wood. [ABSTRACT FROM AUTHOR]

The injection process is one of the relevant phenomena occurring in modern diesel engine considering also that the fuel properties have been continuously changing. The interaction mechanisms between fuel quality, engine technologies, and emissions need to be understood to find the most effective approach towards innovative combustion strategies and low-emission diesel engines. In this work, the injection process occurring in a direct injection (DI) Common Rail (CR) diesel engine has been investigated from the start of injection up to the start of luminous combustion using different techniques. 2D visible and infrared imaging has been applied in single cylinder optical engine for several injection strategies typical of passenger car engine (homologation cycle NEDC). The spray penetration and cone angle obtained by 2D imaging are compared with the results of a 1D consolidated model for transient spray developed by the Sandia National Laboratory. Some modifications to the model boundary conditions have been made in order to assess the effect of fuel–wall interaction. This provided qualitative information of the impinged fuel inside the piston bowl. Finally, a good correlation between the fuel mass impinging on the chamber wall and the particulate matter (PM) emissions measured at the engine exhaust was found. The results of this study could be helpful for the determination of the best injection strategies in a diesel engine in order to reduce PM emissions. [ABSTRACT FROM AUTHOR]

Unexpected combustions dispersion due to variations in fuel quality, production tolerance, and aging of components results in the deterioration of engine performance and increases harmful emissions. Many researchers have studied real-time combustion monitoring and control to maintain peiformance even under undesirable or abnormal conditions. They have reported that the reduction of combustion dispersion is promising for the decrease of emissions dispersion. In this study, we control the maximum heat release (HR) to compensate for combustion dispersion and compared the relationship between before and after control. The maximum rate of heat release (ROHRmax) is an important parameter and is highly related to engine performance and emission level. The control experiments were carried out using a diesel engine at 1500 rpm and brake mean effective pressure (BMEP) of 400 kPa, while the engine parameters were varied. The varied parameters were fuel rail pressure, swirl valve, pilot injection timing, and duration. The experimental results showed that control of the ROHRmax has the potential for the reduction of the dispersions of particulate matter (PM) emission and combustion noise even in unexpected combustion environments. [ABSTRACT FROM AUTHOR]

Raw biomass washing prior to pyrolysis treatment has been employed to mitigate the ash-related problems encountered during resultant biochar combustion. However, wide-spread application of this approach is limited by high energy consumption and low washing efficiency. In the present study, the biochar washing instead of raw biomass washing was attempted to overcome aforementioned problems, and fuel qualities of washed biochars were investigated for the first time. The results showed that major ash forming metals can be efficiently removed by all tested washing agents (de-ionized water (DW), acetic acid (AA) and citric acid (CA)), especially for acid washing agents AA and CA. As a consequence, the ash content of the biochars decreased, and the slagging and fouling issues were dramatically mitigated. Due to metal removal, the washed biochars exhibited improved combustion properties, especially for the biochars derived from agricultural biomass. In addition, noticeable decreases in nitrogen and sulfur contents were observed following washing treatment, suggesting the additional benefit of reducing emissions of nitrogen and sulfur pollutants during washed biochar combustion. Compared to raw biomass washing prior to pyrolysis, the significantly increased washing efficiency and fuel quality and decreased hydrophilicity of the biochars indicate that pyrolysis combined with subsequent biochar washing is more suitable to produce solid fuel biochars with high fuel quality from different source of waste biomass. [ABSTRACT FROM AUTHOR]

This paper presents a model predictive control (MPC) strategy for BioGrate boiler, compensating the main disturbances caused by variations in fuel quality such as the moisture content of fuel, and variations in fuel flow. The MPC utilizes models, the fuel moisture soft-sensor to estimate water evaporation, and the fuel flow calculations to estimate the thermal decomposition of dry fuel, to handle these variations, the inherent large time constants, and long time delays of the boiler. The MPC strategy is compared with the method currently used in the BioPower 5 CHP plant. Finally, the results are presented, analyzed and discussed. [ABSTRACT FROM AUTHOR]

This paper presents a model predictive control (MPC) strategy for efficient energy production in BioGrate boiler. In addition to compensating for the main disturbances caused by variations in fuel quality such as fuel moisture content, and variations in fuel feed, this strategy models water evaporation, and models and controls the fuel bed height of the grate. Usually, combustion power in a furnace have been estimated by utilizing oxygen consumption. There is however a need for more accurate prediction and control of combustion power, which is greatly affected by the fuel bed height and fuel moisture content. It is shown that water evaporation and thermal decomposition of dry fuel can be estimated by utilizing fuel moisture soft-sensor and oxygen consumption calculations respectively. As a result, the primary air can be adjusted to produce the necessary combustion power, and the power output of the boiler can be accurately predicted. This enables efficient stabilization of plant operations. To verify the model, experiments were performed at a BioPower 5 CHP plant, which utilizes BioGrate combustion technology to enable the use of wet biomass fuels with a moisture content as high as 65%. Then the MPC strategy was compared with the currently used control strategy. Finally, the results are presented, analyzed, and discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] The performance of HTC and LTP was compared to produce solid fuel from waste biomass. [•] Fuel qualities of the biochars produced from HTC and LTP were investigated. [•] Ash problem related metal contents in two biochars were analyzed. [•] Combustion characteristics of two biochars were determined. [•] Hydrothermally prepared biochar is suitable for use as a solid fuel. [ABSTRACT FROM AUTHOR]

This work investigated on the effect of co-hydrothermal carbonization (co-HTC) of polyvinyl chloride (PVC) and alkali coal on combustion and slagging characteristics of the generated fuels (hydrochar). Fuel properties were assessed in terms of ultimate and proximate analysis, functional groups evolution, and ash melting characteristics. The loss of C–O functional groups in coal would be accompanied by the liberation of some elements such as Na and Ca, which were often associated with such groups. The hydrochars presented higher ignition temperature and average combustion rates compared with raw coal. The hydrochar generated from co-HTC at 250 °C showed the best combustion performance due to the enhancement of air contacting and transformation, which was attributed to its porous structure, smaller uniform particle, and relative higher surface area. The activation energy of hydrochars was increased at the ignition stage while was decreased at the combustion stage according to the kinetic analysis. The fusion temperature was increased resulting from the removal of alkali and alkaline earth metals (AAEMs) during the co-HTC process. From the perspective of waste-to-energy, the co-HTC of high-alkali coal and PVC seems to be a feasible solution to improve combustion and slagging characteristics. • Co-hydrothermal carbonization of PVC/alkali coal produced high quality fuel. • Lower H/C and O/C atomic ratio were achieved with raising the HTC temperature. • Co-HTC postponed the ignition but improved the combustion rate of hydrochars. • Abundant pores and surface area promoted combustion of hydrochars. • Co-HTC improved the ash fusing temperature thus preventing slagging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of soluble nanocatalyst TiO2 examined in the diesel engine. • Performance and emission parameters are determined for six engine speeds at different concentration of nanoparticles. • Increased concentration of the blends improves the performance of the engine irrespective of engine speeds. • NOx accumulation increased due to the addition of blends. Biofuels were getting an enormous attention to be used as fuel for diesel engines. This paper examines the effect of addition of nanoparticles in biofuel on diesel engines. The biofuel used for conducting tests was canola oil. Corn oil was mixed with titanium dioxide (TiO 2) at different proportions as 25 ppm, 50 ppm, 75 ppm and 100 ppm. These nanoparticles mixed with biofuel and diesel. The nanoparticles were dispersed with biodiesel at the concentration of B10T25 (10% cornoil + 90% diesel + TiO 2 25), B10T50, B10T75, B10T100, B20T25, B20T50, B20T75, and B20T100 and plain biodiesel are B10 and B20. All tests were carried at different speeds 1800 rpm, 2000 rpm, 2200 rpm, 2400 rpm, 2600 rpm and 2800 rpm. Performance and emission characteristics were estimated for all fuel blends. Results were compared to each other to characterize the fuel blend quality. The addition of titania with biofuel increased the performance qualities such as brake thermal efficiency (BTE), exhaust gas temperature (EGT), Torque and Power. Further this combination reduced the Greenhouse gas emissions such as CO, CO 2 , and UHC. The specific fuel consumption (SFC) was also reduced and proved to be the better alternative to existing fossil fuel. However, the emission of NOx was increased. [ABSTRACT FROM AUTHOR]

Among several cool-season grasses, tall wheatgrass (Elymus elongatus (Host) Runemark) has been recently identified as a promising energy crop for Mediterranean low productive areas under rainfed conditions. The influence of annual N top dressing applications (0, 30, and 80 kg ha−1) on the production, composition and combustion quality properties of tall wheatgrass biomass was studied for 9 years on marginal land. The effect of harvest time was evaluated from early summer until late winter with three cultivars of tall wheatgrass ('Alkar', 'Jose', and 'Riparianslopes'). Biomass production grew with increasing N input and spring rainfall. The 80 kg N ha−1 treatment provided mean dry matter production of 4.1 Mg ha−1 yr−1 but elevated biomass N levels from 8.5 to 10.0 g kg−1. An autumn harvest in mid-October led to dry matter losses of 16%, and reduced moisture (−48%), ash (−24%), N (−39%), Cl (−61%), S (−24%) and ash K 2 O (−41%) levels. Delaying harvest time until late winter greatly improved fuel quality, reducing N by 51%, and Cl and K by 80–85%, while increasing deformation and flow temperatures by 370 °C and 240 °C, respectively, but led to matter losses of 36–48%. The differences found in the chemical composition of tall wheatgrass across years and N applications up to 80 kg N ha−1 yr−1 are not expected to be of any practical relevance if this type of biomass is utilised in combustion processes. On the contrary, a harvest delay can improve quality properties for combustion. • Tall wheatgrass production and composition evaluated in marginal conditions. • Biomass production increased with N top dressing application and spring rainfall. • Low N inputs do not affect biomass composition significantly. • Delaying harvest time greatly improves biomass composition and fuel quality. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an enhanced method for estimating fuel quality in a BioGrate combustion process and the method’s use in control strategy improvement. This method is based on a dynamic model that makes use of combustion power estimates – which can be calculated based on the furnaces oxygen consumption – and that makes use of a nonlinear dynamic model of the secondary superheater. The paper focuses to estimate the most essential combustion parameters: fuel moisture and fuel flow. The time delay for detecting a change in fuel moisture and fuel flow is small enough for the method to be used for controlling both air and fuel feed, preventing any steam and pressure oscillations. The proposed control strategy is compared with the method currently used in the BioPower 5 CHP plant. Finally, the results are analyzed and discussed. [Copyright &y& Elsevier]

Abstract: Increased use of pellets has resulted in a shortage of the traditional raw materials required for pellet making, including saw dust, shavings and cuttings from saw mills. Therefore, the pellets industry has started to look for alternative raw materials. Limited consumption of pulpwood from Scots pine (Pinus sylvestris L.) in Norway has made it a potential raw material for the pellets industry. A study on how bark content affects the quality of pellets is reported in this paper. Pellets from pinewood containing zero, five, 10, 30 and 100 percent bark were produced, and their quality parameters were evaluated. Combustion tests were also performed on the produced pellets. Pellets made from pure bark had the best mechanical properties compared with pellets made of wood containing various concentrations of bark. The differences were not substantial and the durability for all chosen assortments was in the same quality class in the CEN standard. A positive effect off the amount of steam added was found. The bulk densities of the blend pellets were higher than those of pure wood and bark. The ash content increased with the amount of bark in the pellets. There were no problems with sintering when the bark content was low (five and 10 percent). For pure bark pellets some sintering was registered. [Copyright &y& Elsevier]