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Publications (10 of 30) Show all publications
Hedayati, A. (2020). Ash transformation in single-pellet combustion and gasification of biomass with special focus on phosphorus. (Licentiate dissertation). Luleå University of Technology, 258
Open this publication in new window or tab >>Ash transformation in single-pellet combustion and gasification of biomass with special focus on phosphorus
2020 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The utilization of different biomass feedstocks in thermal conversion systems can contribute towards mitigation of global warming. However, the formation of different ash fractions (i.e., bottom ash, and fly ash) during thermal conversionof biomass can cause several ash-related problems such as deposit formation, slagging, and particle emissions, all of which may limit its usage as an energy source. It has been found that phosphorus (P), even in relatively low concentrations, can play a vitalrole in the abovementioned ash-related problems. However, the ash transformation reactions occurring in the thermal conversion of P-bearing biomass assortments are not fully understood and rarely described in the literature. Therefore, an understanding ofthe phenomena associated with ash transformations with a special focus on P is crucial.

The overall objective was to determine the ash transformation and release of P duringsingle-pelletthermochemical conversion ofdifferent types of agricultural and forest fuelsin the low to medium temperature range (600-950 °C). Different agricultural biomasses (poplar, wheat straw, grass, and wheat grain residues), as well as forest residues (bark, twigs, and a mixture of bark and twigs) were used. Thebark and poplar fuels represent a fuel rich in K and Ca with minor P contents. The wheat straw, grass, and twigs represent a typical Si- and K-rich fuel with minor and moderate P contents. The wheat grain residues represent a typical K- and P-rich fuel witha considerable amount of Mg. The produced residual materials, i.e. chars and ashes, were characterized by SEM-EDS, XRD, and ICP-OES. The experimental results were interpreted with support from thermodynamic equilibrium calculations (TECs).

The overall findings are that the majority of P (>80%) in all the studied fuels remained in the final condensed residues, and that the main fraction of P release occurred during the devolatilization stage. The chemical form of P in the residuesis strongly dependent on the relative concentrations of other major ash-forming elements such as K, Ca, and Si, as well as the type of association of P in the pure fuel. For woody-based fuels rich in Ca and K (poplar, bark, and twigs in this study), P in theash is generally found in the form of crystalline hydroxyapatite. For herbaceous fuels rich in Si and K (wheat straw and grass), P in the ash is generally found in Ca5(PO4)3OH, Ca15(PO4)2(SiO4),KCaPO4, and K-Ca/Mg phosphosilicate melts. For wheat grain residues rich in P, K, and Mg, P in the ash is found in crystalline forms K4Mg4(P2O7)3, K2MgP2O7,K2CaP2O7, and KMgPO4, as well as amorphous K-Mg/Ca phosphates.

The obtained new knowledge can be used to find practical measures to mitigate ash-related problems during thermochemical conversion of P-bearing biomass fuels. It can also be used to find optimal pyrolysis process conditions to obtain biocharsuitable as alternative fuels and reducing agents in the metallurgical industry.

Place, publisher, year, edition, pages
Luleå University of Technology, 2020
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-60525 (URN)978-91-7790-583-7 (ISBN)978-91-7790-584-4 (ISBN)
Presentation
2020-06-12, E632, Lulea university of Technology, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2020-04-17 Created: 2020-04-17 Last updated: 2020-05-25Bibliographically approved
Vuorinen, E., Hosseini, N., Hedayati, A., Kornacker, E., Fernandez, M. T., Sanz, J., . . . Cañibano, E. (2020). Mechanical and microstructural evaluation of high performance steel (S700MC) for road restraint systems. Engineering Failure Analysis, 108, Article ID 104251.
Open this publication in new window or tab >>Mechanical and microstructural evaluation of high performance steel (S700MC) for road restraint systems
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2020 (English)In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 108, article id 104251Article in journal (Refereed) Published
Abstract [en]

The suitability of using high performance steel (S700MC) for road restraint systems (RRS) under very high containment level was evaluated in this study. To investigate the influence of the crash on the mechanical behaviour of the steel, different test pieces were tested by tensile and hardness testing, and examined by scanning electron microscopy (SEM). The tensile test results of S700MC showed a noticeable increase in yield strength at 0.2% elongation (Rp0.2) from 744 to 935 MPa, and ultimate tensile strength (UTS) from 810 to 1017 MPa, before and after crash tests (BC and AC, respectively). S700MC showed ~9% lower elongation at fracture value in comparison with S275JR and S355JR steels. Besides, fracture toughness, was significantly higher for S700MC (133 and 148 MJ/m3 for BC and AC, respectively) compared to conventional mild steels (108–118 MJ/m3). Microstructural observations of head-part of all S700MC samples revealed equi-axed grains. The fracture surface of tensile tested samples before crash, showed elongated grains accompanied by pore formation. Among after crash samples, one test piece showed intergranular cracks while no intergranular cracks were observed for the other crashed pieces which resulted in the lower Rp0.2 (813 MPa) and UTS strength (847 MPa) and fracture toughness (125 MJ/m3). The results showed that although RRS manufactured with S700MC undergoes severe mechanical deformation, the risk of brittle fracture is very low and this is beneficial from industrial as well as social point of view.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Failure analysis, Fracture toughness, Hydrogen-assisted cracking, Mechanical testing, Microstructures
National Category
Metallurgy and Metallic Materials Energy Engineering Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-76929 (URN)10.1016/j.engfailanal.2019.104251 (DOI)000505213100037 ()2-s2.0-85075357040 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-01-27 (johcin)

Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2020-04-27Bibliographically approved
Forouzan, F., Gunasekaran, S., Hedayati, A., Vuorinen, E. & Mücklich, F. (2017). Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel. Paper presented at 8th conference of Materials Structure & Micromechanics of Fracture (MSMF8), Brno, Czech republic, 27-29 June, 2016. Solid State Phenomena, 258, 574-578
Open this publication in new window or tab >>Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel
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2017 (English)In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 258, p. 574-578Article in journal (Refereed) Published
Abstract [en]

Gleeble study of the quenching and partitioning (Q&P) process has been performed onDomex 960 steel (Fe, 0.08 %C, 1.79 %Mn, 0.23 %Si, 0.184 %Ti, and 0.038 %Al). The effect ofdifferent Q&P conditions on microstructure and mechanical properties were investigated. The aimof the process is to produce a fine grained microstructure for better ductility and controlled amountsof different micro-constituents to increase the strength and toughness simultaneously. Threedifferent quenching temperatures, three partitioning temperatures and three partitioning times havebeen selected to process the 27 specimens by Gleeble® 1500. The specimens were characterized bymeans of OM, SEM, XRD, hardness and impact tests. It was found that, fine lath martensite withretained austenite is achievable without high amount of Si or Al in the composition although lack ofthese elements may cause the formation of carbides and decrease the available amount of carbon forpartitioning into the austenite. The hardness increases as the quenching temperature is decreased,however, at highest partitioning temperature (640◦C) the hardness increases sharply due to extensiveprecipitate formation.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2017
Keywords
AHSS, Gleeble, Quenching and partitioning (Q&P), X-ray, mechanical properties
National Category
Other Materials Engineering
Research subject
Engineering Materials; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-60479 (URN)10.4028/www.scientific.net/SSP.258.574 (DOI)2-s2.0-85009754153 (Scopus ID)
Conference
8th conference of Materials Structure & Micromechanics of Fracture (MSMF8), Brno, Czech republic, 27-29 June, 2016
Note

Konferensartikel i tidskrift

Available from: 2016-11-16 Created: 2016-11-16 Last updated: 2019-03-04Bibliographically approved
Hedayati, A., Asghari, S., Alinoori, A. H., Koosha, M. & Vuorinen, E. (2016). Effects of coating thickness on corrosion and contact resistance behavior of TiN coated AISI 316L as bipolar plates for PEMFC. Iranian Journal of Hydrogen & Fuel Cell, 3(2), 137-149
Open this publication in new window or tab >>Effects of coating thickness on corrosion and contact resistance behavior of TiN coated AISI 316L as bipolar plates for PEMFC
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2016 (English)In: Iranian Journal of Hydrogen & Fuel Cell, ISSN 2383-1618, Vol. 3, no 2, p. 137-149Article in journal (Refereed) Published
Abstract [en]

In the polymer electrolyte membrane fuel cells (PEMFCs), low corrosion resistance and high interfacial contact resistance (ICR) are two controversial issues in usage of AISI 316L stainless steel as a metallic bipolar plate. For solving these problems, investigation and development of different coatings and/or surface treatments are inevitable. Corrosion behavior and ICR of AISI 316L specimens coated with 1, 2, and 3 µm thick TiN were investigated. Potentiodynamic (PD), potentiostatic (PS) and electrochemical impedance spectroscopy (EIS) tests were conducted at 80 °C in pH3 H2SO4+2 ppm HF solution purged with either O2 or H2 under both simulated cathodic and anodic conditions. The PS corrosion test results revealed that the current densities of the specimens were below 1 µA cm−2. In the simulated cathodic condition, an increase of coating thickness from 1 to 3 µm led to a relatively large decrease of the current density from 0.76 to 0.43 µA cm−2. Furthermore, the ICR values of the coated specimens after the PS test were lower than that of the uncoated specimen before the PS. In general, the TiN coating decreases the ICR, and has enough corrosion resistance in simulated PEMFC conditions. However, none of the coatings achieved the DOE ICR targets.

Keywords
Proton Exchange Membrane Fuel Cells, AISI 316L Stainless Steel, Bipolar Plates, PVD Coating, Titanium Nitride (TiN) Coating
National Category
Other Materials Engineering Energy Engineering
Research subject
Engineering Materials; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62053 (URN)10.22104/IJHFC.2017.393 (DOI)
Available from: 2017-02-16 Created: 2017-02-16 Last updated: 2020-01-28Bibliographically approved
Forouzan, F., Gunasekaran, S., Hedayati, A., Vuorinen, E. & Mücklich, F. (2016). Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel. In: MSMF 2016: Materials Structure & Micromechanics of Fracture. Paper presented at 8th International Conference on Materials Structure & Micromechanics of Fracture, Brno, Czech Republic, June 27–29, 2016.
Open this publication in new window or tab >>Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel
Show others...
2016 (English)In: MSMF 2016: Materials Structure & Micromechanics of Fracture, 2016Conference paper, Oral presentation with published abstract (Refereed)
National Category
Metallurgy and Metallic Materials Energy Engineering
Research subject
Engineering Materials; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62293 (URN)
Conference
8th International Conference on Materials Structure & Micromechanics of Fracture, Brno, Czech Republic, June 27–29, 2016
Available from: 2017-03-04 Created: 2017-03-04 Last updated: 2018-03-05Bibliographically approved
Schodek, D. L., Ferreira, P. & Ashby, M. F. (2016). Nanomaterials, nanotechnologies and design: an introduction for engineers and architects. Jahad Daneshgahi Isfahan, 1
Open this publication in new window or tab >>Nanomaterials, nanotechnologies and design: an introduction for engineers and architects
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2016 (Persian)Book (Other academic)
Place, publisher, year, edition, pages
Jahad Daneshgahi Isfahan, 2016
National Category
Engineering and Technology Materials Engineering Nano Technology Mechanical Engineering Other Materials Engineering Energy Engineering
Research subject
Engineering Materials; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62286 (URN)9786008157076 (ISBN)
Available from: 2017-03-04 Created: 2017-03-04 Last updated: 2017-11-24Bibliographically approved
Vuorinen, E., Heino, V., Ojala, N., Haiko, O. & Hedayati, A. (2016). The effects of microstructure on erosive-abrasive wear behavior of carbide free bainitic and boron steels. In: Nordic Symposium on Tribology - NORDTRIB 2016: . Paper presented at 17th Nordic Symposium on Tribology - NORDTRIB 2016, Aulanko, Hämeenlinna, Finland, 14–17 June 2016.
Open this publication in new window or tab >>The effects of microstructure on erosive-abrasive wear behavior of carbide free bainitic and boron steels
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2016 (English)In: Nordic Symposium on Tribology - NORDTRIB 2016, 2016Conference paper, Published paper (Refereed)
National Category
Other Materials Engineering Energy Engineering
Research subject
Engineering Materials; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62050 (URN)
Conference
17th Nordic Symposium on Tribology - NORDTRIB 2016, Aulanko, Hämeenlinna, Finland, 14–17 June 2016
Available from: 2017-02-16 Created: 2017-02-16 Last updated: 2018-03-05Bibliographically approved
Hedayati, A., Asghari, S., Faghilhimmani, B. & Koosha, M. (2013). A coating with highcorrosion resistance and low interfacial contact resistance for metallic bipolar plates of PEMfuel cells. ir 83780.
Open this publication in new window or tab >>A coating with highcorrosion resistance and low interfacial contact resistance for metallic bipolar plates of PEMfuel cells
2013 (Persian)Patent (Other (popular science, discussion, etc.))
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-61700 (URN)
Patent
IR 83780
Available from: 2017-01-30 Created: 2017-01-30 Last updated: 2017-11-24Bibliographically approved
Hedayati, A., Asghari, S. & Alinouri, A. (2013). Corrosion behavior and interfacial contact resistance of TiN coated type 316L stainless steel as bipolar plate for proton exchange membrane fuel cell. In: : . Paper presented at 6th Iranian fuel cell Seminar, Shahid Rajaee Teacher Training University, Tehran, Iran.
Open this publication in new window or tab >>Corrosion behavior and interfacial contact resistance of TiN coated type 316L stainless steel as bipolar plate for proton exchange membrane fuel cell
2013 (English)Conference paper, Published paper (Refereed)
National Category
Materials Engineering Metallurgy and Metallic Materials Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-62291 (URN)
Conference
6th Iranian fuel cell Seminar, Shahid Rajaee Teacher Training University, Tehran, Iran
Available from: 2017-03-04 Created: 2017-03-04 Last updated: 2017-11-24Bibliographically approved
Surkialiabad, R., Hedayati, A. & Alam, A. S. (2013). Monitoring of Martensitic Transformation in Cold-Rolled 304L Austenitic Stainless Steel by Eddy Current Method (ed.). e-Jounral of Nondestructive Testing, 1(10)
Open this publication in new window or tab >>Monitoring of Martensitic Transformation in Cold-Rolled 304L Austenitic Stainless Steel by Eddy Current Method
2013 (English)In: e-Jounral of Nondestructive Testing, ISSN 1435-4934, Vol. 1, no 10Article in journal (Refereed) Published
Abstract [en]

With measuring the volume fraction of martensite, the destruction of the samples would be considered. In this work a 304L AISI austenitic stainless steel was rolled from 10 to 80 % reduction then the formation of martensite phase was monitored by X-ray diffraction, image analysis of optical, SEM microscopy and eddy current investigation. Also eddy current was carried out in the wide range of frequencies from 50 to 10000 Hz to figure out the effect of it on structural changes then the outputs were calibrated by XRD. By comparing the data of these methods relationship between them was found to be a function of exponential regression. In spite, some researchers have previouslyreported a linear relationship.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-3071 (URN)0d68ef29-b293-4248-992b-4c264a78311f (Local ID)0d68ef29-b293-4248-992b-4c264a78311f (Archive number)0d68ef29-b293-4248-992b-4c264a78311f (OAI)
Note

Upprättat; 2013; 20160620 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9088-2286

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