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Ahlström, Peter
Publications (10 of 24) Show all publications
Eboh, F. C., Ahlström, P. & Richards, T. (2017). Exergy Analysis of Solid Fuel-Fired Heat and Power Plants: A Review. Energies
Open this publication in new window or tab >>Exergy Analysis of Solid Fuel-Fired Heat and Power Plants: A Review
2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2017
Keywords
exergy, heat and power, solid fuels, system efficiencies
National Category
Engineering and Technology Energy Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-11885 (URN)10.3390/en10020165 (DOI)000395469200019 ()2-s2.0-85014124644 (Scopus ID)
Available from: 2017-02-02 Created: 2017-02-02 Last updated: 2018-11-29Bibliographically approved
Erdtman, E., Bohlén, M., Ahlström, P., Gkourmpis, T., Berlin, M., Andersson, T. & Bolton, K. (2016). A molecular-level computational study of the diffusion and solubility of water and oxygen in carbonaceous polyethylene nanocomposites. Journal of Polymer Science Part B: Polymer Physics, 54, 589-602
Open this publication in new window or tab >>A molecular-level computational study of the diffusion and solubility of water and oxygen in carbonaceous polyethylene nanocomposites
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2016 (English)In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 54, p. 589-602Article in journal (Refereed) Published
Abstract [en]

Monte Carlo and molecular dynamics simulations were performed to investigate the effect on the solubility, diffusion, and permeability of water and oxygen when adding graphene or single-walled carbon nanotubes (SWCNTs) to polyethylene (PE). When compared with pure PE, addition of graphene lowered the solubility of water, whereas at lower temperatures, the oxygen solubility increased because of the oxygen–graphene interaction. Addition of SWCNTs lowered the solubility of both water and oxygen when compared with pure PE. A detailed analysis showed that an ordered structure of PE is induced near the additive surface, which leads to a decrease in the diffusion coefficient of both penetrants in this region. The addition of graphene does not change the permeation coefficient of oxygen (in the direction parallel to the filler) and, in fact, may even increase this coefficient when compared with pure PE. In contrast, the water permeability is decreased when graphene is added to PE. The addition of SWCNTs decreases the permeability of both penetrants. Graphene can consequently be added to selectively increase the solubility and permeation of oxygen over water, at least at lower temperatures. 

Keywords
diffusion, molecular modeling, nanocomposites, polyethylene (PE), solubility
National Category
Polymer Chemistry
Research subject
Textiles and Fashion (General)
Identifiers
urn:nbn:se:hb:diva-10816 (URN)10.1002/polb.23951 (DOI)000368942900007 ()2-s2.0-84956976939 (Scopus ID)
Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-11-26Bibliographically approved
Eboh, F. C., Ahlström, P. & Richards, T. (2016). Estimating the specific chemical exergy of municipal solid waste. Energy Science & Engineering, 4(3), 217-231
Open this publication in new window or tab >>Estimating the specific chemical exergy of municipal solid waste
2016 (English)In: Energy Science & Engineering, ISSN 2050-0505, Vol. 4, no 3, p. 217-231Article in journal (Refereed) Published
National Category
Energy Engineering
Identifiers
urn:nbn:se:hb:diva-10793 (URN)10.1002/ese3.121 (DOI)000377213700005 ()2-s2.0-85014098626 (Scopus ID)
Available from: 2016-09-28 Created: 2016-09-28 Last updated: 2018-11-29Bibliographically approved
Eboh, F. C., Ahlström, P. & Richards, T. (2016). Estimating the specific exergy of municipal solid waste. Energy Science & Engineering, 4(3), 217-231
Open this publication in new window or tab >>Estimating the specific exergy of municipal solid waste
2016 (English)In: Energy Science & Engineering, ISSN 2050-0505, Vol. 4, no 3, p. 217-231Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
National Category
Energy Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-11085 (URN)10.1002/ese3.121 (DOI)000377213700005 ()2-s2.0-85014098626 (Scopus ID)
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2018-11-29Bibliographically approved
Eboh, F. C., Ahlström, P. & Richards, T. (2016). Method of Estimating Absolute Entropy of Municipal Solid Waste. World Academy of Science, Engineering and Technology, International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering, 10(7), 689-694
Open this publication in new window or tab >>Method of Estimating Absolute Entropy of Municipal Solid Waste
2016 (English)In: World Academy of Science, Engineering and Technology, International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering, E-ISSN 2010-3778, Vol. 10, no 7, p. 689-694Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Absolute entropy, irreversibility, municipal solid waste, waste-to-energy
National Category
Energy Engineering
Identifiers
urn:nbn:se:hb:diva-10794 (URN)
Available from: 2016-09-28 Created: 2016-09-28 Last updated: 2017-05-04Bibliographically approved
Erdtman, E., Ahlström, P., Berlin, M., Andersson, T., Gkourmpis, T. & Bolton, K. (2014). Penetration and absorption of small molecules in polymers. In: : . Paper presented at ESAT 2014. 27th European Symposium on Applied Thermodynamics, Eindhoven, Netherlands, 6-9 July 2014.
Open this publication in new window or tab >>Penetration and absorption of small molecules in polymers
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2014 (English)Conference paper, Published paper (Refereed)
Keywords
Permeation, molecules, polymers, computer simulations, Energi och material
National Category
Materials Chemistry
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-7287 (URN)2320/14507 (Local ID)2320/14507 (Archive number)2320/14507 (OAI)
Conference
ESAT 2014. 27th European Symposium on Applied Thermodynamics, Eindhoven, Netherlands, 6-9 July 2014
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2017-01-22Bibliographically approved
Erdtman, E., Bohlén, M., Ahlström, P., Gkourmpis, T., Berlin, M., Andersson, T. & Bolton Kim, K. (2014). Permeation of water and oxygen through carbonaceous PE composites. In: : . Paper presented at 51st Nordic Polymer Days, June 10-12, Gothenburg Sweden.
Open this publication in new window or tab >>Permeation of water and oxygen through carbonaceous PE composites
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2014 (English)Conference paper, Published paper (Refereed)
Keywords
Theoretical Chemistry
National Category
Theoretical Chemistry
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-7294 (URN)2320/14547 (Local ID)2320/14547 (Archive number)2320/14547 (OAI)
Conference
51st Nordic Polymer Days, June 10-12, Gothenburg Sweden
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2016-11-23Bibliographically approved
Börjesson, A., Erdtman, E., Ahlström, P., Berlin, M., Andersson, T. & Bolton, K. (2013). Molecular modelling of oxygen and water permeation in polyethylene. Polymer, 54(12), 2988
Open this publication in new window or tab >>Molecular modelling of oxygen and water permeation in polyethylene
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2013 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 54, no 12, p. 2988-Article in journal (Refereed)
Abstract [en]

Monte Carlo and molecular dynamics simulations were performed to calculate solubility, S, and diffusion, D, coefficients of oxygen and water in polyethylene, and to obtain a molecular-level understanding of the diffusion mechanism. The permeation coefficient, P, was calculated from the product of S and D. The AMBER force field, which yields the correct polymer densities under the conditions studied, was used for the simulations, and it was observed that the results were not sensitive to the inclusion of atomic charges in the force field. The simulated S for oxygen and water are higher and lower than experimental data, respectively. The calculated diffusion coefficients are in good agreement with experimental data. Possible reasons for the discrepancy in the simulated and experimental solubilities, which results in discrepancies in the permeation coefficients, are discussed. The diffusion of both penetrants occurs mainly by large amplitude, infrequent jumps of the molecules through the polymer matrix.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Permeability, Polyethylene, Molecular simulation, Resursåtervinning, Computational modelling
National Category
Theoretical Chemistry Materials Chemistry Atom and Molecular Physics and Optics
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1569 (URN)10.1016/j.polymer.2013.03.065 (DOI)000319365900020 ()2320/12338 (Local ID)2320/12338 (Archive number)2320/12338 (OAI)
Note

Sponsorship:

KK-stiftelsen

Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01
Erdtman, E., Gebäck, T. & Ahlström, P. (2012). Atomistic Modelling of Protein Superabsorbents. In: : . Paper presented at European Symposium on Applied Thermodynamics the ESAT 2012 Potsdam, Tyskland.
Open this publication in new window or tab >>Atomistic Modelling of Protein Superabsorbents
2012 (English)Conference paper, Poster (with or without abstract) (Other academic)
Keywords
Protein, Superabsorbents, Monte Carlo Simulation
National Category
Theoretical Chemistry Other Chemical Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-6876 (URN)2320/11664 (Local ID)2320/11664 (Archive number)2320/11664 (OAI)
Conference
European Symposium on Applied Thermodynamics the ESAT 2012 Potsdam, Tyskland
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2017-01-22Bibliographically approved
Erdtman, E., Gebäck, T. & Ahlström, P. (2011). Computational modeling of Protein based super-absorbents from waste. Paper presented at Thermodynamics2011, September 1st – September 3rd 2011, Athens, Greece. Paper presented at Thermodynamics2011, September 1st – September 3rd 2011, Athens, Greece.
Open this publication in new window or tab >>Computational modeling of Protein based super-absorbents from waste
2011 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Hydrogels are used for various applications, for example as transporters in drug delivery, in control lenses, and as superabsorbent material in diapers.[1] Most synthetic produced hydrogels are based on synthetic polymers. Even though they are efficient and cheap, they are not biodegradable and sometimes even toxic. To produce more environmental friendly and biodegradable superabsorbent polymers (Bio- SAPs), other building blocks can be used, such as polysaccharides[2] and various protein structures, for example fish shells[3], collagen[4], soy protein[5] and egg protein[6]. Experimental studies at the University of Boras show that it is possible to produce Bio-SAPs from by-products of ethanol production from ligno-cellulose.[2, 6, 7] 2. Method We have studied the absorption properties of protein structures in silico as a comparison to experimental studies. The NPT Gibbs Ensemble Monte Carlo (GEMC) simulation scheme with two phases is used in order to calculate the absorption capacity of the protein. Pure water was simulated in the first GEMC-phase and the peptide in the second phase. The simulations were made with SPC/E water model [8] and the AMBER99 atomistic force field for the peptides [9]. Furthermore, mesoscopic studies with coarse grained force fields have been done. To facilitate faster computations, we used cell lists for the atom-atom interactions, configurational bias algorithm to build the water molecules and the peptide side-chains, and the cavity bias algorithm [10] for molecule insertions. Model peptides have been studied with varying secondary structure, temperature and protonation (pH). We also plan to study how cross-links affect the absorption. One of the peptides we study is a 20 amino acid long peptide called SSP1.[11] This peptide is designed to form a fibrous structure a hydrogel, and its structure is well defined. We have also studied a peptide which changes secondary structure when changing the pH, and concentration.[12] This makes it possible to compare absorption properties with respect to the secondary structure. 3. Conclusion We have simulated peptides with the Gibbs Ensemble Monte Carlo scheme in order to study the water absorption rate dependent of structure, charge, pH and temperature. This information is useful when developing new biodegradable superabsorbent materials.

Keywords
superabsorbents, gibbs ensemble monte carlo, resouce recovery, Energi och material
National Category
Theoretical Chemistry Other Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-6609 (URN)2320/9127 (Local ID)2320/9127 (Archive number)2320/9127 (OAI)
Conference
Thermodynamics2011, September 1st – September 3rd 2011, Athens, Greece
Available from: 2015-12-22 Created: 2015-12-22
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