KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS
In the previous part of paper research on rate of carbon oxidation from cokeash residue of long wood and straw pellets with insulated ends were presented. Assuming the rate of carbon oxidation is the same across surface of cokeash particle durations of carbon full burnout were calculated for residue...
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| Дата: | 2017 |
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| Формат: | Стаття |
| Мова: | Ukrainian |
| Опубліковано: |
Institute of Renewable Energy National Academy of Sciences of Ukraine
2017
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| Онлайн доступ: | https://ve.org.ua/index.php/journal/article/view/29 |
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| Назва журналу: | Vidnovluvana energetika |
Репозитарії
Vidnovluvana energetika| id |
veorgua-article-29 |
|---|---|
| record_format |
ojs |
| institution |
Vidnovluvana energetika |
| collection |
OJS |
| language |
Ukrainian |
| topic |
solid biofuels pellets cokeash residue carbon burning out rate anisotropy твердое биотопливо гранулы коксозольный остаток углерод выгорание скорость анизотропия тверде біопаливо гранули коксозольний залишок вуглець вигорання швидкість анізотропія |
| spellingShingle |
solid biofuels pellets cokeash residue carbon burning out rate anisotropy твердое биотопливо гранулы коксозольный остаток углерод выгорание скорость анизотропия тверде біопаливо гранули коксозольний залишок вуглець вигорання швидкість анізотропія Zhovmir, M. KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS |
| topic_facet |
solid biofuels pellets cokeash residue carbon burning out rate anisotropy твердое биотопливо гранулы коксозольный остаток углерод выгорание скорость анизотропия тверде біопаливо гранули коксозольний залишок вуглець вигорання швидкість анізотропія |
| format |
Article |
| author |
Zhovmir, M. |
| author_facet |
Zhovmir, M. |
| author_sort |
Zhovmir, M. |
| title |
KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS |
| title_short |
KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS |
| title_full |
KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS |
| title_fullStr |
KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS |
| title_full_unstemmed |
KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS |
| title_sort |
kinetics of thermolysis and burning of solid biofuel particles. part 4. influence of pellets anisotropy on oxidation rate of carbon from cokeash residue in axial and radial directions |
| title_alt |
КІНЕТИКА ТЕРМОЛІЗУ ТА ВИГОРАННЯ ЧАСТОК ТВЕРДОГО БІОПАЛИВА. ЧАСТИНА 4. ВПЛИВ АНІЗОТРОПІЇ ГРАНУЛ НА ШВИДКІСТЬ ОКИСЛЕННЯ ВУГЛЕЦЮ З КОКСОЗОЛЬНОГО ЗАЛИШКУ В ОСЬОВОМУ ТА РАДІАЛЬНОМУ НАПРЯМКАХ КИНЕТИКА ТЕРМОЛИЗА И ВЫГОРАНИЯ ЧАСТИЦ ТВЕРДОГО БИОТОПЛИВА. ЧАСТЬ 4. ВЛИЯНИЕ АНИЗОТРОПИИ ПЕЛЛЕТ НА СКОРОСТЬ ОКИСЛЕНИЯ УГЛЕРОДА ИЗ КОКСО-ЗОЛЬНОГО ОСТАТКА В ОСЕВОМ И РАДИАЛЬНОМ НАПРАВЛЕНИИ |
| description |
In the previous part of paper research on rate of carbon oxidation from cokeash residue of long wood and straw pellets with insulated ends were presented. Assuming the rate of carbon oxidation is the same across surface of cokeash particle durations of carbon full burnout were calculated for residue of different length pellets. It was a satisfactory matching of the calculated and experimental data for long pellets (above 20-25 mm), but for a shorter ones calculations gave data significantly exceeding experimental.
Observations on progress of carbon burnout from pellet’s cokeash residue allowed assume anisotropy on carbon oxidation rate in axial and radial directions.
Based on analysis of pellet production features in presses with ring or flat shaped die with rolls it can be supposed more significant biomass compacting in axial (longitudinal) direction
of pellet than that in transversal (radial) direction.
It is known that the thermal conductivity of porous solids grows with increase of their density. Due to predominant biomass compressing in axial direction, one can assume that the density and thermal conductivity of wood pellets in the axial direction should be higher than in the radial, i.e. biofuel pellet and cokeash residue formed out of it are anisotropic. Intensification of the transfer phenomena in direction of greater material density can stipulate the increase of carbon oxidization rate in axial (longitudinal) direction of pellets.
This paper provides results of experimental and analytical–experimental research on carbon burning out rate from cokeash residue of wood and straw pellets in axial (longitudinal) direction.
Mathematical model of carbon burning out from cokeash residue formed from thin round plate cut from cylindrical pellet is proposed. Dependence for determining rate of carbon burning out in axial direction wca is based on experimental data about dimensions of round plate, its mass and duration of complete burnout:
here: ρc – average carbon density in particle of cokeash residue; δ0 – semithickness of round plate cut from pellet; tb – duration of carbon complete burnout from round plate of cokeash residue.
Experiments were carried out at temperature in muffle furnace 700oC and free air access with same lots of pellets as in previous paper. It was found carbon burning out rate from cokeash residue of 6 mm wood pellets in axial direction is wca = 3.2 g/(m2s) and is 1.7…2.0 times higher than that in radial direction, and for cokeash residue of 6mm straw pellets wca = 2.3…2.5 g/(m2s) is 1.4…1.5 times higher than that in radial direction. That should to be taken into account at calculation of pellets burning duration. |
| publisher |
Institute of Renewable Energy National Academy of Sciences of Ukraine |
| publishDate |
2017 |
| url |
https://ve.org.ua/index.php/journal/article/view/29 |
| work_keys_str_mv |
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| first_indexed |
2024-06-01T14:33:25Z |
| last_indexed |
2024-06-01T14:33:25Z |
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1800669658519437312 |
| spelling |
veorgua-article-292019-01-01T13:02:49Z КІНЕТИКА ТЕРМОЛІЗУ ТА ВИГОРАННЯ ЧАСТОК ТВЕРДОГО БІОПАЛИВА. ЧАСТИНА 4. ВПЛИВ АНІЗОТРОПІЇ ГРАНУЛ НА ШВИДКІСТЬ ОКИСЛЕННЯ ВУГЛЕЦЮ З КОКСОЗОЛЬНОГО ЗАЛИШКУ В ОСЬОВОМУ ТА РАДІАЛЬНОМУ НАПРЯМКАХ KINETICS OF THERMOLYSIS AND BURNING OF SOLID BIOFUEL PARTICLES. PART 4. INFLUENCE OF PELLETS ANISOTROPY ON OXIDATION RATE OF CARBON FROM COKEASH RESIDUE IN AXIAL AND RADIAL DIRECTIONS КИНЕТИКА ТЕРМОЛИЗА И ВЫГОРАНИЯ ЧАСТИЦ ТВЕРДОГО БИОТОПЛИВА. ЧАСТЬ 4. ВЛИЯНИЕ АНИЗОТРОПИИ ПЕЛЛЕТ НА СКОРОСТЬ ОКИСЛЕНИЯ УГЛЕРОДА ИЗ КОКСО-ЗОЛЬНОГО ОСТАТКА В ОСЕВОМ И РАДИАЛЬНОМ НАПРАВЛЕНИИ Zhovmir, M. solid biofuels pellets cokeash residue carbon burning out rate anisotropy твердое биотопливо гранулы коксозольный остаток углерод выгорание скорость анизотропия тверде біопаливо гранули коксозольний залишок вуглець вигорання швидкість анізотропія In the previous part of paper research on rate of carbon oxidation from cokeash residue of long wood and straw pellets with insulated ends were presented. Assuming the rate of carbon oxidation is the same across surface of cokeash particle durations of carbon full burnout were calculated for residue of different length pellets. It was a satisfactory matching of the calculated and experimental data for long pellets (above 20-25 mm), but for a shorter ones calculations gave data significantly exceeding experimental. Observations on progress of carbon burnout from pellet’s cokeash residue allowed assume anisotropy on carbon oxidation rate in axial and radial directions. Based on analysis of pellet production features in presses with ring or flat shaped die with rolls it can be supposed more significant biomass compacting in axial (longitudinal) direction of pellet than that in transversal (radial) direction. It is known that the thermal conductivity of porous solids grows with increase of their density. Due to predominant biomass compressing in axial direction, one can assume that the density and thermal conductivity of wood pellets in the axial direction should be higher than in the radial, i.e. biofuel pellet and cokeash residue formed out of it are anisotropic. Intensification of the transfer phenomena in direction of greater material density can stipulate the increase of carbon oxidization rate in axial (longitudinal) direction of pellets. This paper provides results of experimental and analytical–experimental research on carbon burning out rate from cokeash residue of wood and straw pellets in axial (longitudinal) direction. Mathematical model of carbon burning out from cokeash residue formed from thin round plate cut from cylindrical pellet is proposed. Dependence for determining rate of carbon burning out in axial direction wca is based on experimental data about dimensions of round plate, its mass and duration of complete burnout: here: ρc – average carbon density in particle of cokeash residue; δ0 – semithickness of round plate cut from pellet; tb – duration of carbon complete burnout from round plate of cokeash residue. Experiments were carried out at temperature in muffle furnace 700oC and free air access with same lots of pellets as in previous paper. It was found carbon burning out rate from cokeash residue of 6 mm wood pellets in axial direction is wca = 3.2 g/(m2s) and is 1.7…2.0 times higher than that in radial direction, and for cokeash residue of 6mm straw pellets wca = 2.3…2.5 g/(m2s) is 1.4…1.5 times higher than that in radial direction. That should to be taken into account at calculation of pellets burning duration. Висунуто припущення про вплив анізотропії циліндричних гранул біопалива на швидкість окислення вуглецю в осьовому та радіальному напрямках. Аналітично отримана залежність для визначання швидкості вигорання вуглецю з коксозольного залишку гранул біопалива в осьовому напрямку з використанням експериментальних даних про розміри круглої пластини біопалива, її маси та тривалості повного вигорання. Експериментально визначена швидкість окислення вуглецю з коксозольного залишку в осьовому напрямку значно вища ніж у радіальному, що необхідно враховувати при розрахунку тривалості горіння гранул. Выдвинуто предположение о влиянии анизотропии цилиндрических пеллет биотоплива на скорость окисления углерода в осевом и радиальном направлениях. Аналитически получена зависимость для определения скорости выгорания углерода из коксозольного остатка пеллет биотоплива в осевом направлении с использованием экспериментальных данных о размере круглой пластины, ее массы и продолжительность полного выгорания. Экспериментально определенная скорость окисления углерода из коксозольного остатка в осевом направлении выше, чем в радиальном, что необходимо учитываться при расчете продолжительности горения пеллет. Institute of Renewable Energy National Academy of Sciences of Ukraine 2017-12-14 Article Article application/pdf https://ve.org.ua/index.php/journal/article/view/29 Возобновляемая энергетика; № 4 (51) (2017): Научно-прикладной журнал Возобновляемая энергетика; 93-100 Відновлювана енергетика; № 4 (51) (2017): Науково-прикладний журнал Відновлювана енергетика; 93-100 Vidnovluvana energetika ; No. 4 (51) (2017): Scientific and Applied Journal Vidnovluvana energetika; 93-100 2664-8172 1819-8058 uk https://ve.org.ua/index.php/journal/article/view/29/21 https://creativecommons.org/licenses/by/4.0/ |