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| 3. |
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| 4. |
- Aad, G., et al.
(author)
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- 2010
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swepub:Mat__t
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| 5. |
- Aad, G., et al.
(author)
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- 2011
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swepub:Mat__t
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| 6. |
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| 7. |
- Aad, G., et al.
(author)
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- 2010
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swepub:Mat__t
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| 8. |
- Aad, G., et al.
(author)
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- 2010
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swepub:Mat__t
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| 9. |
- Aad, G., et al.
(author)
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- 2010
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swepub:Mat__t
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| 10. |
- Aslanzadeh, Solmaz, et al.
(author)
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An Overview of Existing Individual Unit Operations
- 2014
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In: Biorefineries. - : Elsevier Inc.. - 9780444594983
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Book chapter (peer-reviewed)abstract
- BACKGROUND: Because of its extreme toxicity for microorganisms, the limonene content of citrus wastes (CWs) has been a major obstacle to the conversion of CWs to biofuels. The main objective of this study was to develop a new process for the utilization of CWs that can be economically feasible when the supply of CW is low.RESULTS: Steam explosion pre-treatment was applied to improve the anaerobic digestibility of CWs, resulting in a decrease of initial limonene concentration by 94.3%. A methane potential of 0.537 ± 0.001 m 3 kg -1 VS (volatile solids) was obtained during the following batch digestion of treated CWs, corresponding to an increase of 426% compared with that of the untreated samples. Long-term effects of the treatment were further investigated by a semi-continuous co-digestion process. A methane production of 0.555 ± 0.0159 m 3 CH 4 kg -1 VS day -1 was achieved when treated CWs (corresponding to 30% of the VS load) were co-digested with municipal solid waste.CONCLUSION: The process developed can easily be applied to an existing biogas plant. The equipment cost for this process is estimated to be one million USD when utilizing 10 000 tons CWs year -1. 8.4 L limonene and 107.4 m 3 methane can be produced per ton of fresh citrus wastes in this manner.
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| 11. |
- Baird, Denis A., et al.
(author)
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Identification of Novel Loci Associated With Hip Shape : A Meta-Analysis of Genomewide Association Studies.
- 2019
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In: Journal of Bone and Mineral Research. - : Wiley-Blackwell. - 0884-0431 .- 1523-4681. ; 34:2, s. 241-251
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Journal article (peer-reviewed)abstract
- We aimed to report the first genomewide association study (GWAS) meta-analysis of dual-energy X-ray absorptiometry (DXA)-derived hip shape, which is thought to be related to the risk of both hip osteoarthritis and hip fracture. Ten hip shape modes (HSMs) were derived by statistical shape modeling using SHAPE software, from hip DXA scans in the Avon Longitudinal Study of Parents and Children (ALSPAC; adult females), TwinsUK (mixed sex), Framingham Osteoporosis Study (FOS; mixed), Osteoporotic Fractures in Men study (MrOS), and Study of Osteoporotic Fractures (SOF; females) (total N = 15,934). Associations were adjusted for age, sex, and ancestry. Five genomewide significant (p < 5 × 10-9 , adjusted for 10 independent outcomes) single-nucleotide polymorphisms (SNPs) were associated with HSM1, and three SNPs with HSM2. One SNP, in high linkage disequilibrium with rs2158915 associated with HSM1, was associated with HSM5 at genomewide significance. In a look-up of previous GWASs, three of the identified SNPs were associated with hip osteoarthritis, one with hip fracture, and five with height. Seven SNPs were within 200 kb of genes involved in endochondral bone formation, namely SOX9, PTHrP, RUNX1, NKX3-2, FGFR4, DICER1, and HHIP. The SNP adjacent to DICER1 also showed osteoblast cis-regulatory activity of GSC, in which mutations have previously been reported to cause hip dysplasia. For three of the lead SNPs, SNPs in high LD (r2 > 0.5) were identified, which intersected with open chromatin sites as detected by ATAC-seq performed on embryonic mouse proximal femora. In conclusion, we identified eight SNPs independently associated with hip shape, most of which were associated with height and/or mapped close to endochondral bone formation genes, consistent with a contribution of processes involved in limb growth to hip shape and pathological sequelae. These findings raise the possibility that genetic studies of hip shape might help in understanding potential pathways involved in hip osteoarthritis and hip fracture. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.
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| 12. |
- Berglund, Per, et al.
(author)
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Linking Education and Research : A Roadmap for Higher Education Institutions at the Dawn of the Knowledge Society
- 2019
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In: Linking education and research. - Basel, Switzerland : MDPI. ; , s. 11-33
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Book chapter (other academic/artistic)abstract
- In an era characterized by a move towards a “knowledge society”, universities are central in fostering “knowledgeability”, that is the reflexive understanding of knowledge in knowledge societies. The objective of “knowledgeability” can be met through creating a stronger link between education and research. Furthermore, overall student performance, for example in critical thinking and problem solving, can be improved if research-related activities are incorporated into the curriculum.The aim of this paper is to use international examples to discuss the research- education nexus from four different perspectives, namely context, policy, implementation and quality, with case studies from higher education institutions in Singapore and Sweden.We suggest that different integrative technologies can be used to enhance the links, but it will be essential to consider the inputs of training, service and support in using new technology. Interestingly, the act of evaluating the link between education and research will increase awareness of this linkage by stakeholders involved in both education and research. In turn the link can be strengthened, contributing to increased quality in both education and research.
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| 13. |
- Berntsson, Thore, 1947, et al.
(author)
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Towards Sustainabel Oil Refinery - Pre-study for larger co-operation project
- 2008
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Reports (other academic/artistic)abstract
- In this report, the Chalmers EnergiCentrum (CEC) presents the results of a pre-study commissioned by Preem relating to the effective production of future vehicle fuels.This pre-study was made up of three studies focusing on energy streamlining, the utilisation of waste heat and carbon-dioxide separation and biorefinement relating to the gasification and hydration of vegetable oils. One of the common starting points for these studies was the current situation at the Preem refineries in Göteborg and Lysekil from where the measurement data were obtained and analysed. The report summarises the knowledge situation based on current research in the individual technical fields. The results present some interesting future opportunities for developing the sustainable production of future vehicle fuels. The sections vary, as the areas that have been examined differ and the sections have been written by different people. The reports ends with some joint conclusions and a number of questions which could be included and answered in a more extensive future main study, as part of a developed research partnership between Preem and the Chalmers University of Technology. The preliminary results of this work were analysed with the client at workshops on 1 October and 29 November 2007. The report is written in English combined with an extensive summary in Swedish including a proposal on a future main study. The study was conducted by the Chalmers EnergiCentrum (CEC), in collaboration with a number of researchers in the CEC’s network. They included Thore Berntsson, Jessica Algehed, Erik Hektor and Lennart Persson Elmeroth, all from Heat and Power Technology, Börje Gevert, Chemical and Biological Engineering, Tobias Richards, Forest Products and Chemical Engineering, Filip Johnsson and Anders Lyngfelt, Energy Technology, and Per-Åke Franck and Anders Åsblad, CIT Industriell Energianalys AB. The client, Preem, was represented by Bengt Ahlén, Sören Eriksson, Johan Jervehed, Bertil Karlsson, Gunnar Olsson, Ulf Kuylenstierna, Stefan Nyström, Martin Sjöberg and Thomas Ögren. Tobias Richards was responsible for compiling the report and Bertil Pettersson was the project manager.
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| 14. |
- Bloom, Bard, et al.
(author)
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Thorn-Robust, Concurrent, Extensible Scripting on the JVM
- 2009
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In: SIGPLAN notices. - New York, NY, USA : ACM. - 0362-1340 .- 1558-1160. ; 44:10, s. 117-136
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Journal article (peer-reviewed)abstract
- Scripting languages enjoy great popularity due to their support for rapid and exploratory development. They typically have lightweight syntax, weak data privacy, dynamic typing, powerful aggregate data types, and allow execution of the completed parts of incomplete programs. The price of these features comes later in the software life cycle. Scripts are hard to evolve and compose, and often slow. An additional weakness of most scripting languages is lack of support for concurrency-though concurrency is required for scalability and interacting with remote services. This paper reports on the design and implementation of Thorn, a novel programming language targeting the JVM. Our principal contributions are a careful selection of features that support the evolution of scripts into industrial grade programs-e.g., an expressive module system, an optional type annotation facility for declarations, and support for concurrency based on message passing between lightweight, isolated processes. On the implementation side, Thorn has been designed to accommodate the evolution of the language itself through a compiler plugin mechanism and target the Java virtual machine.
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| 15. |
- Bolton, Kim, et al.
(author)
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DFT study of the adsorption and dissociation of water on Ni(111), Ni(110) and Ni(100) surfaces
- 2014
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In: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 627, s. 1-10
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Journal article (peer-reviewed)abstract
- Water adsorption and dissociation on catalytic metal surfaces play a key role in a variety of industrial processes, and a detailed understanding of this process and how it is effected by the surface structure will assist in developing improved catalysts. Hence, a comparative study of the adsorption and dissociation of water on Ni(111), Ni(110) and Ni(100) surfaces, which is often used as catalyst, has been performed using density functional theory. The results show that the adsorption energies and dissociation rates depend on the surface structure. The adsorption energies for H2O and OH decrease in the order Ni(110) > Ni(100) > Ni(111), and for the O and H atoms the adsorption energies decrease in the order Ni(100) > Ni(111) > Ni(110). In addition, the splitting of water to OH and H has lower activation energies over less packed Ni(110) and Ni(100) surfaces compared to the highly packed Ni(111) surface. The subsequent splitting of the OH to O and H also has the lowest activation energy on the Ni(110) surface. At 463 K, which is typical for industrial processes that include the water gas shift reaction, the H2O splitting is approximately 6000 and 10 times faster on the Ni(110) surface compared to the Ni(111) and Ni(100) surfaces, respectively, and OH splitting is 200 and 3000 times faster, respectively. The complete water dissociation reaction rate decreases in the order Ni(110) > Ni(100) > Ni(111).
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| 16. |
- Chandolias, Konstantinos, 1985-, et al.
(author)
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Combined gasification-fermentation process in waste biorefinery
- 2018
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In: Waste Biorefinery. - : Elsevier. - 9780444639929
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Book chapter (peer-reviewed)abstract
- Thermal processes of wastes lead to production of energy in form of electricity and/or heat. However, if the goal is to produce materials, thermochemical processes can be applied. These processes via e.g. gasification produce raw syngas that is a mixture of principally H2, CO and CO2, with some impurities. This raw syngas is traditionally cleaned and catalytically treated via chemical processes such as Fischer-Tropsch. However, as there is a variety of microorganisms that can assimilate syngas, this gas can be used as a substrate to produce different chemicals via biochemical routes. This chapter is dedicated to describe an efficient thermochemical-biochemical route of waste treatment. The gasification process, the design and the factors that affect the syngas composition are firstly described. Thereafter, the microbiology, biochemical reactions, metabolic pathways and process conditions toward production of several metabolic products from syngas such as carboxylic acids, ethanol, butanol, 2,3-butanediol, methane and biopolymers are presented.
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| 17. |
- Cuvilas, Carlos Alberto
(author)
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Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal.In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours.
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| 18. |
- Donaj, Pawel
(author)
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Conversion of biomass and waste using highly preheated agents for materials and energy recovery
- 2011
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Doctoral thesis (other academic/artistic)abstract
- One of the greatest challenges of human today is to provide the continuous and sustainable energy supply to the worldwide society. This shall be done while minimizing all the negative consequences of the operation(s) to the environment and its living habitants including human beings, taking from the whole life cycle perspective. In this thesis work new solutions for treatment biomass and waste are analyzed. Based on the fundamental research on the conversion of various materials (biomass: straw pellets, wood pellets; and waste: plastic waste, ASR residues after pyrolysis), converted by means of different systems (pyrolysis in a fluidized bed reactor, gasification in a fixed-bed reactor using highly preheated agents) it is recommended to classify materials against their charring properties under pyrolysis, in order to find the best destination for a given type of fuel. Based on phenomenological research it was found that one of the important effects, affecting performance of downdraft gasifiers, is the pressure drop through the bed and grate. It affects, directly, the velocity profile, temperature distribution and of the height of the bed, especially for the grate with restricted passage surface, although it was not investigated in literature. The lower grate porosity, the higher conversion of fuel and heating value of gas is produced. However, the stability of the process is disturbed; therefore reducing the grate porosity below 20% is not recommended, unless the system is designed to overtake the consequences of the rising pressure inside the reactor. This work proposed the method for prediction of a total pressure drop through the fixed-bed downdraft gasifier equipped with a grate of certain porosity with an uncertainty of prediction ±7.10. Three systems have been proposed; one for the treatment of automotive shredder residue (ASR), one for the treatment of plastic waste (polyolefins) and one for biomass (wood/straw pellets). Pyrolysis is an attractive mean of conversion of non-charring materials (like plastic waste) into valuable hydrocarbons feedstock. It gives directly 15-30% gaseous olefins while the residue consisting of naphtha-like feedstock has to be reformed/upgraded to olefins or other chemicals (e.g. gasoline generation) using available petrochemical technologies. Pyrolysis of complex waste mixture such as ASR is an attractive waste pretreatment method before applying any further treatments, whereby useful products are generated (gaseous and liquid fuel) and char, rich in precious metals. The solid residues are meant for further treatment for energy and metals recovery. Gasification is a complementary method for handling pyrolysis residues. However, metals can be removed before gasification. Pyrolysis of charring materials, like biomass, is a very important step in thermo-chemical conversion. However, the char being approximately 25%wt. contains still very high caloric value of about 30MJ/kg. This in connection with the High Temperature Steam Gasification process is a very promising technology for biomass treatment, especially, above 900oC. This enhances the heat transfer towards the sample and accelerates kinetics of the gasification. This, in turn, improves the conversion of carbon to gas, increases the yield of the producer gas and reduces tar content. At higher steam to fuel ratio the process increases the yield of hydrogen, making it suitable for second-generation biofuels synthesis, whereas at lower steam to fuel ratio (S/F<2) the generated gas is of high calorific value making it suitable for power generation in a combined cycle.
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| 19. |
- Eboh, Francis Chinweuba, et al.
(author)
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Economic evaluation of improvements in a waste-to-energy combined heat and power plant
- 2019
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In: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456.
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Journal article (peer-reviewed)abstract
- Improving the efficiency of waste-to-energy combined heat and power plants increases their production of both electricity and heat. Economic evaluation of such improvements enables adequate decisions to be made between the various alternatives with respect to economic viability of the plant. In this study, the cost and profitability of different modifications to improve efficiency in a waste-to-energy plant are considered: these include the re-arrangement of air heaters, the introduction of a reheater, flue gas condensation (FGC) and an integrated gasification-combustion process. The base case and the modifications are evaluated and compared when operating either as a combined heat and power plant or as a power plant. Modelling, simulation and cost estimations were performed with the Aspen Plus software. Although the integrated gasification-combustion technology with FGC has the highest exergy efficiency, its higher capital cost is greater than all of the other alternatives. Modification 6, which involves both re-arrangement and changing the air heating medium has the lowest capital cost with respect to enhancing exergy efficiency. Modifications 1 and 7, involving FGC, are the best alternatives for the capital cost per total unit of revenue generated. These modifications not only provides the highest heat production but also the highest net present value (NPV). The base case and the modifications investigated all have positive NPV, indicating that a waste-to-energy combined heat and power plant is an attractive investment. However, an increase of about 122% in the gate fees would be required for a system with only electricity production to be profitable.
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| 20. |
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| 21. |
- Eboh, Francis Chinweuba, et al.
(author)
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Estimating the specific exergy of municipal solid waste
- 2016
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In: Energy Science & Engineering. - : John Wiley & Sons. - 2050-0505. ; 4:3, s. 217-231
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Journal article (peer-reviewed)abstract
- A new model for predicting the specific chemical exergy of municipal solid waste (MSW) is presented; the model is based on the content of carbon, hydrogen, oxygen, nitrogen, sulfur, and chlorine on a dry ash-free basis (daf). The proposed model was obtained from estimations of the higher heating value (HHV) and standard entropy of MSW using statistical analysis. The ultimate analysis of 56 different parts of MSW was used for the derivation of the HHV expression. In addition, 30 extra parts were used for validation. One hundred and seventeen relevant organic substances that represented the main constituents in MSW were used for derivation of the standard entropy of solid waste. The substances were divided into different waste fractions, and the standard entropies of each waste fraction and for the complete mixture were calculated. The specific chemical exergy of inorganic matter in the waste was also investigated by considering the inorganic compounds in the ash. However, as a result of the extremely low value calculated, the exergy of inorganic matter was ignored. The results obtained from the HHV model show a good correlation with the measured values and are comparable with other recent and previous models. The correlation of the standard entropy of the complete waste mixture is less accurate than the correlations of each individual waste fraction. However, the correlations give similar results for the specific chemical exergy, indicating that HHV has a greater impact when estimating the specific exergy of solid waste than entropy.
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| 22. |
- Eboh, Francis Chinweuba, et al.
(author)
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Evaluating improvements in a waste-to-energy combined heat and power plant
- 2019
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In: Case Studies in Thermal Engineering. - : Elsevier. - 2214-157X.
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Journal article (peer-reviewed)abstract
- Evaluation of different alternatives for enhancement in a waste combustion process enables adequate decisions to be made for improving its efficiency. Exergy analysis has been shown be an effective tool in assessing the overall efficiency of a system. However, the conventional exergy method does not provide information of the improvements possible in a real process. The purpose of this paper is to evaluate state-of-the art techniques applied in a municipal solid-waste fired heat and power plant. The base case plant is evaluated first; the results are then used to decide upon which technical modifications should be introduced and they are thereafter evaluated. A modified exergy-based method is used to discover the improvement potential of both the individual components and the overall base case plant. The results indicate that 64% of exergy destruction in the overall process can theoretically be improved. The various modifications selected involve changing the bed material, using a gasifier followed by a gas boiler and incorporating a more durable material into the boiler walls. In addition, changing the heating medium of the incoming air (from steam to flue gas) along with a reduction in the stack temperature and the integration of flue gas condensation were considered for utilizing the exergy in the flue gases. The modification involving gasifier, gas boiler and flue gas condensation proved to be the best option, with the highest exergy efficiency increment of 21%.
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| 23. |
- Eboh, Francis Chinweuba, et al.
(author)
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Exergy Analysis of Solid Fuel-Fired Heat and Power Plants: A Review
- 2017
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In: Energies. - Basel, Switzerland : MDPI. - 1996-1073.
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Journal article (peer-reviewed)abstract
- The growing demand for energy is particularly important to engineers with respect to how the energy produced by heat and power plants can be used efficiently. Formerly, performance evaluation of thermal power plants was done through energy analysis. However, the energy method does not account for irreversibilities within the system. An effective method to measure and improve efficiency of thermal power plant is exergy analysis. Exergy analysis is used to evaluate the performance of a system and its main advantage is enhancement of the energy conversion process. It helps identify the main points of exergy destruction, the quantity and causes of this destruction, as well as show which areas in the system and components have potential for improvements. The current study is a comprehensive review of exergy analyses applied in the solid fuels heat and power sector, which includes coal, biomass and a combination of these feedstocks as fuels. The methods for the evaluation of the exergy efficiency and the exergy destruction are surveyed in each part of the plant. The current review is expected to advance understanding of exergy analysis and its usefulness in the energy and power sectors: it will assist in the performance assessment, analysis, optimization and cost effectiveness of the design of heat and power plant systems in these sectors.
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| 24. |
- Eboh, Francis Chinweuba, et al.
(author)
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Method of Estimating Absolute Entropy of Municipal Solid Waste
- 2016
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In: World Academy of Science, Engineering and Technology, International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering. - 2010-3778. ; 10:7, s. 689-694
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Journal article (peer-reviewed)abstract
- Entropy, as an outcome of the second law of thermodynamics, measures the level of irreversibility associated with any process. The identification and reduction of irreversibility in the energy conversion process helps to improve the efficiency of the system. The entropy of pure substances known as absolute entropy is determined at an absolute reference point and is useful in the thermodynamic analysis of chemical reactions; however, municipal solid waste (MSW) is a structurally complicated material with unknown absolute entropy. In this work, an empirical model to calculate the absolute entropy of MSW based on the content of carbon, hydrogen, oxygen, nitrogen, sulphur, and chlorine on a dry ash free basis (daf) is presented. The proposed model was derived from 117 relevant organic substances which represent the main constituents in MSW with known standard entropies using statistical analysis. The substances were divided into different waste fractions; namely, food, wood/paper, textiles/rubber and plastics waste and the standard entropies of each waste fraction and for the complete mixture were calculated. The correlation of the standard entropy of the complete waste mixture derived was found to be somsw= 0.0101C + 0.0630H + 0.0106O + 0.0108N + 0.0155S + 0.0084Cl (kJ.K-1.kg) and the present correlation can be used for estimating the absolute entropy of MSW by using the elemental compositions of the fuel within the range of 10.3% ≤ C ≤ 95.1%, 0.0% ≤ H ≤ 14.3%, 0.0% ≤ O ≤ 71.1%, 0.0 ≤ N ≤ 66.7%, 0.0% ≤ S ≤ 42.1%, 0.0% ≤ Cl ≤ 89.7%. The model is also applicable for the efficient modelling of a combustion system in a waste-to-energy plant.
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| 25. |
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