scholarly journals Διεργασίες ενεργειακής αξιοποίησης βιομάζας για εφαρμογές θέρμανσης και ψύξης

2021 ◽  
Author(s):  
Αντώνιος Νάζος
Keyword(s):  
Muffle Furnace ◽  
Severity Factor

Πολλές πρόσφατες μελέτες έχουν επικεντρωθεί στη θερμικά προκατεργασμένη λιγνοκυτταρινούχο βιομάζα με σκοπό την υποκατάσταση των ορυκτών καυσίμων. Οι μελέτες αυτές ασχολήθηκαν με την αποδοτικότερη χρήση των ανανεώσιμων πηγών ενέργειας, για την διασφάλιση βιώσιμων πρότυπων στην παραγωγή και στην κατανάλωση, πετυχαίνοντας έτσι την εκπλήρωση των στόχων με αρ. 7 και αρ. 12 της Βιώσιμης Ανάπτυξης σύμφωνα με την ατζέντα των Ηνωμένων Εθνών για το 2030. Η χρήση ανανεώσιμων πηγών ενέργειας και ιδιαίτερα της βιομάζας είναι σημαντική λόγω των οικονομικών συντελεστών, καθώς η χρήση χαμηλού κόστους πηγών ενέργειας είναι πιο ελκυστική, ενισχύοντας έτσι τη διατήρηση ενός καθαρού περιβάλλοντος. Οι θερμικές εφαρμογές είναι οι πιο συνηθισμένες και καθιερωμένες χρήσεις της βιομάζας παγκοσμίως. Έχουν αναπτυχθεί αρκετά συστήματα θέρμανσης και ψύξης, με βάση τη βιομάζα, τα οποία είναι εμπορικά διαθέσιμα και οικονομικώς ανταγωνιστικά. Η βιομάζα χρησιμοποιείται με διάφορους τρόπους για την θέρμανση. Τα συστήματα θέρμανσης καλύπτουν ένα ευρύ φάσμα οικιακής θέρμανσης, από μια μονοκατοικία με λέβητες λίγων kW, έως εγκαταστάσεις λεβήτων πολλών kW στη βιομηχανία και την τηλεθέρμανση. Οι θερμικές μονάδες μεγάλης ισχύος μπορούν να συνδυάσουν τα ‘κύκλα ισχύος’ για την συμπαραγωγή θερμότητας και ηλεκτρικής ισχύος (CHP). Καινοτόμες τεχνολογίες όπως είναι ο Οργανικός Κύκλος Rankine (ORC) και η αεριοποίηση, μας προσφέρουν επίσης μια αποτελεσματική συμπαραγωγή. Η παρούσα διατριβή συμβάλλει στην έρευνα αυτή διερευνώντας την αύξηση της Ανώτερης Θερμογόνου Δύναμης (HHV) του άχυρου κριθαριού και σιταριού, μέσω της υγρής και της ξηρής φρύξης, για να χρησιμοποιηθούν αυτά ως στερεό καύσιμο σε συστήματα θέρμανσης και ψύξης. Συγκεκριμένα, στη διαδικασία της υγρής φρύξης διερευνάται η επίδραση του χρόνου, της θερμοκρασίας και της συγκέντρωσης του οξέος. Επιπλέον, για την προσαρμογή των πειραματικών δεδομένων εφαρμόστηκαν καινοτόμα κινητικά μοντέλα χρησιμοποιώντας έναν παράγοντα σοβαρότητας (Severity Factor, Rο) ο οποίος συνδυάζει την επίδραση του χρόνου αντίδρασης, της θερμοκρασίας και τηςσυγκέντρωσης του οξέος, στην περίπτωση μιας μη ισοθερμοκρασιακής διεργασίας. Ειδικότερα, η δυνατότητα βελτίωσης της HHV του άχυρου κριθαριού πραγματοποιήθηκε με (i) Ξηρή φρύξη, η οποία καλείται και απλά φρύξη, σε κλίβανο, και (ii) Καταλυόμενη από Οξύ Υγρή Φρύξη (ACWT), ή όξινη υδρόλυση ή υδροθερμική επεξεργασία καταλυόμενη από οξύ, που πραγματοποιήθηκε σε αντιδραστήρα διαλείποντος έργου τύπου αυτοκλείστου 3,75 L Parr 4553. Επίσης, μελετήθηκε το άχυρο σιταριού όσον αφορά την βελτίωση της HHV. Σε όλες τις περιπτώσεις, χρησιμοποιήθηκε θερμιδόμετρο Parr 1341 Plain Jacket Bomb για τη μέτρηση της HHV των δειγμάτων. Επίσης, τα δείγματα μελετήθηκαν με τη χρήση τηςτελικής (Ultimate) και προσεγγιστικής (Proximate) ανάλυσης, καθώς και με μικροσκόπιο ηλεκτρονικής σάρωσης (SEM).Όσον αφορά την προκατεργασία με ACWT, εφαρμόστηκαν δύο διαφορετικές προσεγγίσεις προσομοίωσης: (α) ο συνδυασμένος συντελεστής σοβαρότητας (CSF) και (β) η μεθοδολογία επιφανειακής απόκρισης (RSM) σύμφωνα με τον σχεδιασμό των πειραμάτων (DoE) κατά Box – Behnken. Εξετάστηκαν οι παράμετροι της ACWT, όπως η συγκέντρωσητου θειικού οξέος (SA), η θερμοκρασία και ο χρόνος. Όσον αφορά στην προκατεργασία με ξηρή φρύξη, μελετήθηκαν διάφορες πειραματικές συνθήκες, χρησιμοποιώντας πολλούς συνδυασμούς θερμοκρασίας και χρόνου σε έναν κλίβανο (Nuve Muffle Furnace). Επιπλέον, εφαρμόστηκαν καινοτόμα κινητικά μοντέλα για την προσαρμογή των πειραματικώνδεδομένων χρησιμοποιώντας τον CSF, ο οποίος συνδυάζει την επίδραση της θερμοκρασίας και του χρόνου στη διεργασία της φρύξης. Συμπερασματικά, η προκατεργασία με ACWT και ξηρή φρύξη των άχυρων κριθαριού και σιταριού αύξησε σημαντικά την HHV, στις βέλτιστες συνθήκες προκατεργασίας, με αποτέλεσμα την παραγωγή στερεού καυσίμου προερχόμενου από βιομάζα, το οποίο κρίθηκε κατάλληλο για χρήση σε συστήματα θέρμανσης και ψύξης, στο πλαίσιο της έννοιας της κυκλικής οικονομίας μηδενικών αποβλήτων.

Modified Stress Severity Factor Method Based on 3D-FEM

2014 ◽  
Vol 945-949 ◽  
pp. 1150-1154
Author(s):  
Xiao Hua Yang ◽  
Xue Jun Liu ◽  
Zhao Hu
Keyword(s):  
Fatigue Life ◽  
Stress State ◽  
Experimental Result ◽  
3D Fem ◽  
Severity Factor ◽  
Factor Method ◽  
D Model

The traditional stress severity factor (SSF) approach was applied to analyze the life of aircraft multi-fastener joint. 3-D model was established under simulated state of practical assembling using CATIA, and then the model was imported into ABAQUS to analyze the detail stress state of aircraft multi-fastener joint. The life of aircraft multi-fastener joint was estimated by amending the SSF method. The example shows that the fatigue life by the approach is closer to the experimental result.

The decomposition of ammonia by heat.

1905 ◽  
Vol 74 (497-506) ◽  
pp. 110-117 ◽  
Author(s):  
E. P. Perman ◽  
G. A. S. Atkinson ◽  
William Ramsay
Keyword(s):  
Heated Surface ◽  
Muffle Furnace ◽  
Glass Tubes ◽  
The Subject ◽  
Mercury Manometer

This subject has been already dealt with by Ramsay and Young, who heated ammonia in glass tubes at various temperatures, and found that decomposition began under the most favourable circumstances at a little below 500°, and that the amount decomposed depends on the extent of the heated surface of the solid with which the ammonia is in contact, on the nature of the surface, and on the time of exposure to heat. We have thought it desirable to extend our knowledge of the subject still further by investigating the rate of decomposition at various temperatures. The ammonia was contained in porcelain vessels heated in a muffle furnace, and the decomposition was traced by reading the pressure on a mercury manometer, the sum of the volumes of the ammonia and products of decomposition being kept constant.

EXAMINATION OF THERMOPHYSICAL CHARACTERISTICS OF A HEAT-PROTECTIVE MATERIAL BASED ON FIBERGLASS DURING DESTRUCTION

2021 ◽  
pp. 91-97
Author(s):  
D.Ya. Barinov ◽  
◽  
S.Yu. Shorstov ◽  
M.G. Razmahov ◽  
A.I. Gulyaev ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermophysical Properties ◽  
Thermal Effects ◽  
Space Technology ◽  
Muffle Furnace ◽  
Thermophysical Characteristics ◽  
Initial State ◽  
Protective Material ◽  
Temperature Dependences

When designing advanced samples of aviation and rocket and space technology, during the operation of which the temperature on the surface of the material can exceed the temperature of destruction, it is important to have an understanding of the values of thermophysical properties. The work investigates the thermophysical properties of fiberglass in the initial state and after the binder is burned out in a muffle furnace. The temperature dependences of thermal effects, heat capacity, thermal diffusivity and thermal conductivity were determined, density was measured, and thermogravimetric analysis was carried out. Using a stereomicroscope, the microstructure of the lateral cut of the samples was examined and its evolution was determined during the burning of the binder.

Optimum torrefaction range for Macaw husks aiming its use as a solid biofuel

2021 ◽  
pp. 1-28
Author(s):  
Robson L Silva ◽  
Omar Seye ◽  
Paulo P. S. Schneider
Keyword(s):  
Energy Density ◽  
Mass Loss ◽  
Energy Content ◽  
Residence Times ◽  
Biomass Feedstock ◽  
Severity Factor ◽  
Optimization Criteria ◽  
Residual Biomass ◽  
Solid Biofuel

Abstract Biomass feedstock is broadly available in many countries and a significant amount of residual biomass comes from agriculture and forest crops. This study aims to identify a consistent criteria for optimize Macaw husks torrefaction process maximizing the energy content and minimizing the mass loss. The optimization criteria is based on the Severity Factor (SF), HHVTorrified and ηSolid-Yield. The energy density (ρEnergy) does not provide consistent and indisputable evidence as an optimization criteria; the same applies to Energy-Mass Co-benefit Index (EMCI) and ηEnergy-Yield. This investigation combined few temperatures (180°C, 220°C, and 260°C) with different residence times (20, 40, and 60 min) and found that the optimum torrefaction range for Macaw husk is 220

scholarly journals Induction Motors Dynamic Eccentricity Fault Diagnosis Based on the Combined Use of WPD and EMD-Simulation Study

2018 ◽  
Vol 8 (10) ◽  
pp. 1709 ◽  
Author(s):  
Kun Tian ◽  
Tao Zhang ◽  
Yibo Ai ◽  
Weidong Zhang
Keyword(s):  
Wavelet Packet ◽  
Frequency Domain Analysis ◽  
Severity Factor ◽  
Mode Decomposition ◽  
Fault Severity ◽  
Combined Use ◽  
Dynamic Eccentricity ◽  
Fault Severity Factor ◽  
Low Degrees ◽  
Cage Induction Motor

The frequency-domain analysis using the fast Fourier transform (FFT) for diagnosis of eccentricity fault has been widely used in squirrel-cage induction motor (IM). However, with the restriction of sampling frequency and time acquisition, FFT analysis could not provide ideal results under low levels of dynamic eccentricity (DE). In this paper, a combined use of the wavelet packet decomposition (WPD) and empirical mode decomposition (EMD) method is presented to diagnose the IM fault under low degrees of purely DE. The proposed method is based on the decomposition of apparent power signal and extracts the characteristic component. The fault severity factor (FSF) has been defined to evaluate the eccentricity severity. Simulation results using the finite element method (FEM) are tested to verify the effectiveness of the presented method under different load conditions.

scholarly journals Effect of severity factor on the hydrothermal pretreatment of sugarcane straw

2019 ◽  
Vol 275 ◽  
pp. 321-327 ◽  
Author(s):  
Gustavo Batista ◽  
Renata B.A. Souza ◽  
Bruna Pratto ◽  
Martha S.R. dos Santos-Rocha ◽  
Antonio J.G. Cruz
Keyword(s):  
Hydrothermal Pretreatment ◽  
Severity Factor ◽  
Sugarcane Straw

scholarly journals Rapid Production of Graphite Without Contamination for Biomedical AMS

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 344-350 ◽  
Author(s):  
John S. Vogel
Keyword(s):  
Isotopic Fractionation ◽  
Cross Contamination ◽  
Biological Variability ◽  
Muffle Furnace ◽  
New Class ◽  
Large Numbers ◽  
Rapid Production ◽  
Disposable Plastic ◽  
Single Reaction

The application of AMS to the detection of 14C makes possible a new class of sensitive experiments in molecular biology. Such experiments inherently produce large numbers of samples for the determination of biological variability in molecular interactions. The samples vary in 14C concentration over many orders of magnitude. We added TiH2 to aid the reduction of CO2 by zinc in a sealed tube to reproducibly make graphite without sample cross-contamination. The CO2 is transferred from a combustion tube to the reaction tube through a disposable plastic manifold. The sealed tubes are heated to a single-reaction temperature in a muffle furnace. The process is complete within 5 h. Bulk isotopic fractionation in the finished graphite is less than 0.5%.

Utilization of open pit burned household waste ash – a feasibility study in Dhaka

2014 ◽  
Vol 32 (5) ◽  
pp. 397-405
Author(s):  
Md. Obaidul Haque ◽  
Ahmed Sharif
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Bottom Ash ◽  
Open Pit ◽  
Household Waste ◽  
Chemical Compositions ◽  
Muffle Furnace ◽  
Clay Bricks ◽  
Peripheral Area

Informal incineration or open pit burning of waste materials is a common practice in the peripheral area of Dhaka, one of the fastest growing mega-cities in the world. This study deals with the effect of open pit burned (i.e. open burned) household waste bottom ash on fired clay bricks. Between 0 to 50% (by weight) of open pit burned household waste bottom ash was mixed with clay to make bricks. The molded specimens were air-dried at room temperature for 24 h and then oven dried at 100 °C for another 24 h to remove the water. The raw bricks were fired in a muffle furnace to a designated temperature (800, 900 and 1000 °C, respectively). The firing behaviour (mechanical strength, water absorption and shrinkage) was determined. The microstructures, phase compositions and leachates were evaluated for bricks manufactured at different firing temperatures. These results demonstrate that open pit burned ash can be recycled in clay bricks. This study also presents physical observations of the incinerated ash particles and determination of the chemical compositions of the raw materials by wet analysis. Open pit burned ash can be introduced easily into bricks up to 20% wt. The concentrations of hazardous components in the leachates were below the standard threshold for inert waste category landfill and their environmental risk during their use-life step can be considered negligible.

Optimization of steam pretreatment conditions for enzymatic hydrolysis of poplar wood

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Fokko Schütt ◽  
Jürgen Puls ◽  
Bodo Saake
Keyword(s):  
Enzymatic Hydrolysis ◽  
Raw Material ◽  
Steam Pretreatment ◽  
Alkaline Extraction ◽  
Poplar Wood ◽  
Steam Refining ◽  
Severity Factor ◽  
Short Rotation ◽  
Pretreatment Conditions ◽  
Hydrolysis Of

Abstract Steam refining was investigated as a pretreatment for enzymatic hydrolysis of poplar wood from a short rotation plantation. The experiments were carried out without debarking to use an economically realistic raw material. Steam refining conditions were varied in the range of 3–30 min and 170–220°C, according to a factorial design created with the software JMP from SAS Institute Inc., Cary, NC, USA. Predicted steaming conditions for highest glucose and xylose yields after enzymatic hydrolysis were at 210°C and 15 min. Control tests under the optimized conditions verified the predicted results. Further pretreatments without bark showed that the enzymes were not significantly inhibited by the bark. The yield of glucose and xylose was 61.9% of theoretical for the experiments with the whole raw material, whereas the yield for the experiments without bark was 63.6%. Alkaline extraction of lignin from the fibers before enzymatic hydrolysis resulted in an increase of glucose yields from mild pretreated fibers and a decrease for severe pretreated fibers. The extracted lignin had a high content of xylose of up to 14% after very mild pretreatments. On the other hand, molecular weights of the extracted lignin increased substantially after pretreatments with a severity factor above 4. Hence, alkaline extraction of the lignin seems only attractive in a narrow range of steaming conditions.

scholarly journals Peningkatan Produksi Gula Pereduksi dari Tandan Kosong Kelapa Sawit dengan Praperlakuan Asam Organik pada Reaktor Bertekanan

REAKTOR ◽  
2017 ◽  
Vol 16 (4) ◽  
pp. 199
Author(s):  
Fahriya Puspita Sari ◽  
Nissa Nurfajrin Solihat ◽  
Sita Heris Anita ◽  
Fitria Fitria ◽  
Euis Hermiati
Keyword(s):  
Enzymatic Hydrolysis ◽  
Oxalic Acid ◽  
Organic Acid ◽  
Oil Palm ◽  
Maleic Acid ◽  
Reducing Sugar ◽  
Sugar Production ◽  
Empty Fruit Bunch ◽  
Acid Pretreatment ◽  
Severity Factor

ENHANCEMENT OF REDUCING SUGAR PRODUCTION FROM OIL PALM EMPTY FRUIT BUNCH BY PRETREATMENT USING ORGANIC ACID IN PRESSURIZED REACTOR. Organic acids are potential to create more environmentally friendly process in the pretreatment of lignocellulosic biomass for bioethanol production. This study was aimed to investigate the influence of organic acid pretreatment in reducing sugar production in a pressurized reactor with various resident times and temperatures on enzymatic hydrolysis of OPEFB. Two different organic acids (maleic acid and oxalic acid) were used in the pretreatment of oil palm empty fruit bunch (OPEFB) using a pressurized reactor. Factorial design using three different temperatures (170, 180, and 190°C) and four resident times (15, 30, 45, and 60 min) were employed, followed by enzymatic hydrolysis. Each condition conducted two repetitions. Analysis was conducted on the reducing sugar that was produced after saccharification by means of the severity factor of each pretreatment condition. Maleic acid showed higher reducing sugar yield with lower severity factor than oxalic acid with the same operating conditions. The highest yield of reducing sugars (80.84%) was obtained using maleic acid at 170 for 60 minutes with severity factor of 1.836. Keywords: bioethanol; organic acid pretreatment; pressurized reactor; severity factor; oil palm empty fruit bunches;   Abstrak Asam organik berpotensi dalam membantu proses praperlakuan dari biomassa lignoselulosa untuk memproduksi bioetanol yang ramah lingkungan. Penelitian ini bertujuan untuk mengetahui pengaruh asam organik, suhu dan waktu operasi terhadap produksi gula pereduksi dengan reaktor bertekanan pada tandan kosong kelapa sawit. Dua asam organik yang berbeda yaitu asam oksalat dan asam maleat digunakan untuk proses praperlakuan tandan kosong kelapa sawit (TKKS) dengan bantuan reaktor bertekanan. Dalam proses praperlakuan digunakan tiga suhu yang berbeda yaitu suhu 170, 180, dan 190°C dan empat waktu operasi 15, 30, 45, dan 60 min yang dilanjutkan dengan proses hidrolisis enzimatis. Setiap kondisi dilakukan dua kali pengulangan. Analisa yang digunakan adalah analisa uji gula pereduksi dan severity factor pada kondisi tiap praperlakuan. Asam maleat menunjukkan hasil yang lebih baik dengan severity factor yang lebih rendah dibandingkan menggunakan asam oksalat dengan kondisi operasi yang sama. Hasil yang didapatkan menunjukkan bahwa praperlakuan tandan kosong kelapa sawit dengan bantuan reaktor bertekanan memiliki rendemen gula pereduksi optimum sebesar 80,84% dengan menggunakan asam maleat pada suhu 170°C selama 60 menit dengan severity factor sebesar 1,836. Kata kunci: bioetanol; praperlakuan asam organik; reaktor bertekanan; severity factor; tandan kosong kelapa sawit.

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