Change search
Refine search result
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Eboh, Francis Chinweuba
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ahlström, Peter
    University of Borås, Faculty of Textiles, Engineering and Business.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business.
    Estimating the specific chemical exergy of municipal solid waste2016In: Energy Science & Engineering, ISSN 2050-0505, Vol. 4, no 3, p. 217-231Article in journal (Refereed)
  • 2.
    Eboh, Francis Chinweuba
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Resource Recovery.
    Ahlström, Peter
    Richards, Tobias
    Estimating the specific exergy of municipal solid waste2016In: Energy Science & Engineering, ISSN 2050-0505, Vol. 4, no 3, p. 217-231Article in journal (Refereed)
    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.

  • 3.
    Eboh, Francis Chinweuba
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ahlström, Peter
    University of Borås, Faculty of Textiles, Engineering and Business.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business.
    Evaluating improvements in a waste-to-energy combined heat and power plant2019In: Case Studies in Thermal Engineering, ISSN 2214-157XArticle in journal (Refereed)
    Abstract [en]

    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%.

  • 4.
    Eboh, Francis Chinweuba
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery.
    Ahlström, Peter
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery.
    Exergy Analysis of Solid Fuel-Fired Heat and Power Plants: A Review2017In: Energies, ISSN 1996-1073, E-ISSN 1996-1073Article in journal (Refereed)
    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.

  • 5.
    Eboh, Francis Chinweuba
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ahlström, Peter
    University of Borås, Faculty of Textiles, Engineering and Business.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business.
    Method of Estimating Absolute Entropy of Municipal Solid Waste2016In: 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)
    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.

  • 6.
    Eboh, Francis Chinweuba
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Andersson, Bengt-Åke
    University of Borås, Faculty of Textiles, Engineering and Business.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business.
    Economic evaluation of improvements in a waste-to-energy combined heat and power plant2019In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Francis Chinweuba, Eboh
    University of Borås, Faculty of Textiles, Engineering and Business.
    Efficiency Improvements in Waste-to-Energy Combustion Processes: Method Development and Evaluation2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    is the energy recovery method. The electrical efficiency of this technology, however, is generally low when compared with other solid fuel-fired combustion plants as a result of low steam properties. Furthermore, there is lack of efficient methods to evaluate the performance of this system. The energy method, normally used, does not account for exergy destruction due to entropy generated within the system.In this thesis, an exergy model for estimating the maximum available energy in a municipal solid waste and a modified exergy-based method for calculating the improvement potential in a waste-to-energy plant are developed. The exergy model was obtained from estimations of the higher heating value and standard entropy of municipal solid waste from the elemental compositions of the waste using statistical analysis. The improvement potential was derived by comparing the exergy destruction of the real process with its corresponding theoretical process. It was applied in a solid-waste fired heat and power plant to investigate possible improvements in the system as well as the cost of the improvements. The different improvement modifications considered include the re-arrangement of air heaters, the introduction of a reheater, flue gas condensation and an integrated gasification-combustion process. Modelling, simulation and cost estimations were performed with the Aspen Plus software.

    The results showed that the present proposed exergy model was more accurate than the previous models for estimating the maximum available energy in waste material, as the proposed model incorporates all the major elemental constituents as well as the physical composition of the solid waste. Moreover, the results obtained from the higher heating value model show a good correlation with the values measured, and are comparable with other recent and previous models. Furthermore, it was found that 64 % of the total exergy destruction in the process plant investigated can be reduced, while the boiler was identified as a component with the greatest potential for making improvements to the plant. Although the integrated gasification-combustion technology with flue gas condensation has the highest exergy efficiency, its higher capital cost exceeds all other alternatives. The improvement modifications with flue gas condensation not only provide the highest heat production but also the highest net present value. This indicates that flue gas condensation has a significant impact on the overall income generated by waste-to-energy combined heat and power industries.

1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf