Multicomponent Modelling Kinetics and Simultaneous Thermal Analysis of Apricot Kernel Shell Pyrolysis

Apricot kernel shells are naturally available source of biomass with potential for conversion to clean energy through a thermo-chemical process such as pyrolysis. To facilitate further process development, an advanced mathematical model which represents the process kinetics is developed and validated on the thermal decomposition studies using simultaneous thermal analysis, over a temperature range of 30-900 °C, at four heating rates of 5, 10, 15 and 20 °C min−1, under argon atmosphere. Model-free analysis and numerically developed methods were utilized for determination of effective activation energies, pre-exponential factors and the fractional contribution. A novel approach is introduced in order to determine actual pseudo-components of studied biomass that are included in its composition. The comparative study of the obtained kinetic results was also presented. The results obtained strongly indicated that the pseudo-component reaction modelling method could be employed to predict the experimental devolatilization rate and biomass composition with a high likelihood of success

Pljevlja lignite carbon emission charateristics

The anthropogenic emission of GHG especially CO has to be limited and reduced due to their impact on global warming and climate change. Combustion of fossil fuels in the energy sector has a dominant share in total GHG emissions. In order to reduce GHG emission, European Union established a scheme for GHG allowance trading within the community, and the implementation of the European Union emission trading scheme, which is a key to GHG reduction in a cost-effective way. An important part of emission trading scheme is prescribed methodology for monitoring, reporting, and verification of the emission of GHG including characterization of the local fuels combusted by the energy sector. This paper presents lignite characteristics from open-pit mine Borovica-Pljevlja, which has highest coal production in Montenegro (>1.2 Mt per year), including evaluation of its carbon emission factor based on the laboratory analysis of 72 coal samples. Testing of the samples included proximate and ultimate analysis, as well as, net calorific value determination. In accordance with the obtained results, linear correlations between net calorific value and combustible matter content, carbon content and combustible matter content, hydrogen content and combustible matter content, carbon content and net calorific value, were established. Finally, the non-linear analytical correlation between carbon emission factor and net calorific value for Pljevlja lignite was proposed, as a base for the precise calculation of CO emission evaluation

Pljevlja lignite carbon emission characteristics

The anthropogenic emission of GHG especially CO has to be limited and reduced due to 2 their impact on global warming and climate change. Combustion of fossil fuels in the energy sector has a dominant share in total GHG emissions. In order to reduce GHG emission, European Union established a scheme for GHG allowance trading within the community, and the implementation of the European Union emission trading scheme, which is a key to GHG reduction in a cost-effective way. An important part of emission trading scheme is prescribed methodology for monitoring, reporting, and verification of the emission of GHG including characterization of the local fuels combusted by the energy sector. This paper presents lignite characteristics from open-pit mine Borovica- Pljevlja, which has highest coal production in Montenegro (>1.2 Mt per year), including evaluation of its carbon emission factor based on the laboratory analysis of 72 coal samples. Testing of the samples included proximate and ultimate analysis, as well as, net calorific value determination. In accordance with the obtained results, linear correlations between net calorific value and combustible matter content, carbon content and combustible matter content, hydrogen content and combustible matter content, carbon content and net calorific value, were established. Finally, the non-linear analytical correlation between carbon emission factor and net calorific value for Pljevlja lignite was proposed, as a base for the precise calculation of CO emission evaluation

From the Guest Editors

Part one of this issue of the journal Thermal Science is devoted again to the topic of internal combustion engines. These topics deal with motor vehicle energy efficiency, engine performances and exhaust emissions, the application of alternative fuels and the improvements of engine processes. Actually, all these topics dictate the future of motor industry. Over the past two decades, the motor industry has progressively risen to the challenge of reducing the impact of its products on air quality and has already started to address this additional challenge of reducing the climate change impacts of road transport. Many developments based on conventional fossil fuels and technologies are currently being pursued and will continue to contribute to these objectives. The motor industry is also developing the use of alternative fuels and breakthrough vehicle technologies that have the potential to reduce further the climate change impact of the use of motor vehicles. The motor industry has a history of successfully responding to society's mobility needs. In addition to addressing consumer desires for convenient, safe, comfortable and efficient personal transport and cost-effective commercial vehicles, industry has also embraced the wider societal requirement of minimizing the environmental impact of road transport. By 2010, the quality of tail pipe emissions for new vehicles will be such that any further regulated reduction will have a minimal environmental impact. By then, sufficient part of the existing vehicle fleet will have been replaced by newer, less polluting vehicles, to ensure a significant reduction of total emissions from present levels. Any future technological developments in this area will be driven by different factors; namely possible climate change by reducing emissions of known greenhouse gases, dependence on non-European oil reserves and the long term need for sustainable renewable energy sources. In global, regional and national policy development, the major environmental challenge facing the automotive industry now and looking set to remain so in years to come is that of CO2. This challenge is being partially addressed by efforts and commitments of the automotive industry to reduce fuel consumption. However, to achieve a step change in CO2 levels, new technologies and fuels will be required. Rapid technological developments are leading to a diversification in road transport fuel options. It is important that Industry, Government, and Society reach agreement on the ultimate fuels of the future and all parties work to achieve the timely introduction of this goal

Model for estimation of coal self-ignition in stockpile

Pojave samozagrevanja i samopaljenja su izuzetno važne pri skladištenju uglja jer mogu da dovedu do pogoršanja kvaliteta uglja i čitavog niza problema, pa čak i do prekida rada termoenergetskih postrojenja. Ove pojave se posebno proučavaju kod niskokaloričnih ugljeva koji pokazuju veću sklonost ka samopaljenju. U raduje dat pregled postojećih modela i za izabrani model izvršena je analiza uticaja karakteristika skladišta, karakteristika okoline i karakteristika uglja na pojavu samopaljenja.The phenomena of self-heating and self-ignition are very important during the coal storage in stockpile. They can have the influence on decrease of coal quality and cause some problems in the thermal power plant operation. These phenomena are the subject of numerous investigations, especially for low rank coals due to their higher tendency to self-ignition. In this paper, the review of models is presented and for the accepted model the influence of the stockpile, atmospheric conditions and coal characteristics on the self-ignition are analyzed

Model for estimation of coal self-ignition in stockpile

Pojave samozagrevanja i samopaljenja su izuzetno važne pri skladištenju uglja jer mogu da dovedu do pogoršanja kvaliteta uglja i čitavog niza problema, pa čak i do prekida rada termoenergetskih postrojenja. Ove pojave se posebno proučavaju kod niskokaloričnih ugljeva koji pokazuju veću sklonost ka samopaljenju. U raduje dat pregled postojećih modela i za izabrani model izvršena je analiza uticaja karakteristika skladišta, karakteristika okoline i karakteristika uglja na pojavu samopaljenja.The phenomena of self-heating and self-ignition are very important during the coal storage in stockpile. They can have the influence on decrease of coal quality and cause some problems in the thermal power plant operation. These phenomena are the subject of numerous investigations, especially for low rank coals due to their higher tendency to self-ignition. In this paper, the review of models is presented and for the accepted model the influence of the stockpile, atmospheric conditions and coal characteristics on the self-ignition are analyzed

Impact of fuel quality and burner capacity on the performance of wood pellet stove

Pellet stoves may play an important role in Serbia in the future when fossil fuel fired conventional heating appliances are replaced by more efficient and environmentally friendly devices. Experimental investigation was conducted in order to examine the influence of wood pellet quality, as well as burner capacity (6, 8 and 10 kW), used in the same stove configuration, on the performance of pellet stove with declared nameplate capacity of 8 kW. The results obtained showed that in case of nominal load and combustion of pellets recommended by the stove manufacturer, stove efficiency of 80.03% was achieved. The use of lower quality pellet caused additional 1.13 kW reduction in heat output in case of nominal load and 0.63 kW in case of reduced load. This was attributed to less favourable properties and lower bulk and particle density of lower quality pellet. The use of different burner capacity has shown to have little effect on heat output and efficiency of the stove when pre-set values in the control system of the stove were not altered. It is concluded that replacement of the burner only is not sufficient to increase/decrease the declared capacity of the same stove configuration, meaning that additional measures are necessary. These measures include a new set up of the stove control system, which needs to be properly adjusted for each alteration in stove configuration. Without the adjustment mentioned, declared capacity of the stove cannot be altered, while its CO emission shall be considerably increased

Potential usage of fly and bottom ash from thermal power plant ”Nikola Tesla” landfill, Serbia

In Serbia, the ash from power plants has long been labelled as hazardous waste. With the adoption of the appropriate legislation this ash became secondary raw material with the potential usage. In this paper an analysis of the fly and bottom ash composition, which are disposed of in the power plant “Nikola Tesla A” landfill, is presented. Thirty samples, divided into three sets, were analyzed for trace elements As, Ba, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Ti, V and Zn. The first and second set of samples were taken at the depth of 0.0-0.6 m, from cassette III, at the place of waste discharge (set I) and in the centre of the cassette (set II).The third set of samples was taken from the same cassette spot but at the different depth. The estimated variations in quality within individual sets, as well as the comparison between sets I and II, were done. The repeatability of results by the depth of cassette (set III) was also analyzed. The mixture consisting of 79.4% limestone, 17% clay, 0.5% sand, 0.55% iron ore, 0.55% from steel mill waste and 2% ash from the thermal power plant "Nikola Tesla A" was adopted as the reputable mixture for cement making. For concrete making, the same cement mixture was used but with 2.1% of the same ash material added. The results showed possibility of further fly and bottom ash use as the cement and concrete material

Application of different turbulence models for improving construction of small-scale boiler fired by solid fuel

Due to the rapid progress in computer hardware and software, CFD became a powerful and effective tool for implementation turbulence modeling in defined combustion mathematical models in the complex boiler geometries. In this paper the commercial CFD package, ANSYS FLUENT was used to model fluid flow through the boiler, in order to define velocity field and predict pressure drop. Mathematical modeling was carried out with application of Standard, RNG, and Realizable k-ε turbulence model using the constants presented in literature. Three boilers geometry were examined with application of three different turbulence models with variants, which means consideration of 7 turbulence model arrangements in FLUENT. The obtained model results are presented and compared with data collected from experimental tests. All experimental tests were performed according to procedures defined in the standard SRPS EN 303-5 and obtained results are presented in this paper for all three examined geometries. This approach was used for improving construction of boiler fired by solid fuel with heat output up to 35 kW and for selection of the most convenient construction

Influence of ethanol and lead gasoline mixture on engine characteristics

Based on EEC researches, among all fuels produced from renewable sources, besides biodisel, alchochols are considered the most perspective fuel. Bioethanol is name for ethanol produced from biomass and it has numerous advantages compared to gasoline and other fossil fuels, predominantly because of reduced CO2 emission. Additionally, utilisation of bioethanol instead of gasoline leads to reduced emission of CO and aromatic hydrocarbons. Based on numerous investigations carried out all around the world, advantages and disadvantages of bioethanol and gasoline mixture were established. The advantages are: more complete combustion, increase of power and torque, octane number rise, higher volumetric heating value and lower CO2 and toxic components (CO and aromatic hydrocarbons) emission. Disadvantages of utilisation of bioethanol and gasoline mixtures are: higher volumetric consumption, lower heating value, emission of aldechides and content of sulfur acid (originated from some distillation processes). Based on investigations carried out until now it was established that utilisation of gasoline with 10 % of bioethanol facilitate reduction of greenhouse gases emission for 3 - 4 %, if the bioethanol is produced from cereals, and 6 - 8 % if it is produced from celluloses. Zastava Automobili and Fuel and Combustion Lab from the Faculty of Mechanical Engineering, University of Belgrade have carried out investigation of influence of different mixtures of ethanol and leaded gasoline on engine performance. At the beginning, physical and chemical characteristics of the mixtures with 1, 3 and 5 % of ethanol were determined, and afterwards the engine tests of most appropriate mixtures were made. The mixtures were prepared from commercial leaded gasoline and ethanol of 96 % purity. Some of the results from these tests are presented in this paper