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  • 1.
    Assefa, Getashew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Eriksson, Ola
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Frostell, Björn
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Technology assessment of thermal treatment technologies using ORWARE2005In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 46, no 5, p. 797-819Article in journal (Refereed)
    Abstract [en]

    A technology assessment of thermal treatment technologies for wastes was performed in the form of scenarios of chains of technologies. The Swedish assessment tool, ORWARE, was used for the assessment. The scenarios of chains of thermal technologies assessed were gasification with catalytic combustion, gasification with flame combustion, incineration and landfilling. The landfilling scenario was used as a reference for comparison. The technologies were assessed from ecological and economic points of view.

    The results are presented in terms of global warming potential, acidification potential, eutrophication potential, consumption of primary energy carriers and welfare costs. From the simulations, gasification followed by catalytic combustion with energy recovery in a combined cycle appeared to be the most competitive technology from an ecological point of view. On the other hand, this alternative was more expensive than incineration. A sensitivity analysis was done regarding electricity prices to show which technology wins at what value of the unit price of electricity (SEK/kW h).

    Within this study, it was possible to make a comparison both between a combined cycle and a Rankine cycle (a system pair) and at the same time between flame combustion and catalytic combustion (a technology pair). To use gasification just as a treatment technology is not more appealing than incineration, but the possibility of combining gasification with a combined cycle is attractive in terms of electricity production.

    This research was done in connection with an empirical R&D work on both gasification of waste and catalytic combustion of the gasified waste at the Division of Chemical Technology, Royal Institute of Technology (KTH), Sweden.

  • 2. Campana, P. E.
    et al.
    Li, H.
    Zhang, J.
    Zhang, R.
    Liu, J.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE).
    Economic optimization of photovoltaic water pumping systems for irrigation2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 95, p. 32-41Article in journal (Refereed)
    Abstract [en]

    Photovoltaic water pumping technology is considered as a sustainable and economical solution to provide water for irrigation, which can halt grassland degradation and promote farmland conservation in China. The appropriate design and operation significantly depend on the available solar irradiation, crop water demand, water resources and the corresponding benefit from the crop sale. In this work, a novel optimization procedure is proposed, which takes into consideration not only the availability of ground-water resources and the effect of water supply on crop yield, but also the investment cost of photovoltaic water pumping system and the revenue from crop sale. A simulation model, which combines the dynamics of photovoltaic water pumping system, groundwater level, water supply, crop water demand and crop yield, is employed during the optimization. To prove the effectiveness of the new optimization approach, it has been applied to an existing photovoltaic water pumping system. Results show that the optimal configuration can guarantee continuous operations and lead to a substantial reduction of photovoltaic array size and consequently of the investment capital cost and the payback period. Sensitivity studies have been conducted to investigate the impacts of the prices of photovoltaic modules and forage on the optimization. Results show that the water resource is a determinant factor.

  • 3. Campana, Pietro Elia
    et al.
    Holmberg, Aksel
    Pettersson, Oscar
    Klintenberg, Patrik
    Hangula, Abraham
    Araoz, Fabian Benavente
    KTH, School of Chemical Science and Engineering (CHE).
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Stridh, Bengt
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    An open-source optimization tool for solar home systems: A case study in Namibia2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 130, p. 106-118Article in journal (Refereed)
    Abstract [en]

    Solar home systems (SHSs) represent a viable technical solution for providing electricity to households and improving standard of living conditions in areas not reached by the national grid or local grids. For this reason, several rural electrification programmes in developing countries, including Namibia, have been relying on SHSs to electrify rural off-grid communities. However, the limited technical know-how of service providers, often resulting in over-or under-sized SHSs, is an issue that has to be solved to avoid dissatisfaction of SHSs' users. The solution presented here is to develop an open-source software that service providers can use to optimally design SHSs components based on the specific electricity requirements of the end-user, The aim of this study is to develop and validate an optimization model written in MS Excel-VBA which calculates the optimal SHSs components capacities guaranteeing the minimum costs and the maximum system reliability. The results obtained with the developed tool showed good agreement with a commercial software and a computational code used in research activities. When applying the developed optimization tool to existing systems, the results identified that several components were incorrectly sized. The tool has thus the potentials of improving future SHSs installations, contributing to increasing satisfaction of end-users.

  • 4. Campana, Pietro Elia
    et al.
    Li, Hailong
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Yan, Jinyue
    Malardalen Univ.
    Techno-economic feasibility of the irrigation system for the grassland and farmland conservation in China: Photovoltaic vs. wind power water pumping2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 103, p. 311-320Article in journal (Refereed)
    Abstract [en]

    Photovoltaic water pumping (PVWP) and wind power water pumping (WPWP) systems for irrigation represent innovative solutions for the restoration of degraded grassland and the conservation of farmland in remote areas of China. The present work systematically compares the technical and economic suitability of such systems, providing a general approach for the design and selection of the suitable technology for irrigation purposes. The model calculates the PVWP and WPWP systems sizes based on irrigation water requirement (IWR), solar irradiation and wind speed. Based on the lowest PVWP and WPWP systems components costs, WPWP systems can compete with PVWP systems only at high wind speed and low solar irradiation values. Nevertheless, taking into account the average specific costs both for PVWP and WPWP systems, it can be concluded that the most cost-effective solution for irrigation is site specific. According to the dynamic simulations, it has also been found that the PVWP systems present better performances in terms of matching between IWR and water supply compared to the WPWP systems. The mismatch between IWR and pumped water resulted in a reduction of crop yield. Therefore, the dynamic simulations of the crop yield are essential for economic assessment and technology selection. (C) 2015 Elsevier Ltd. All rights reserved.

  • 5. D'Andrea, G.
    et al.
    Gandiglio, M.
    Lanzini, A.
    Santarelli, Massimo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. olitecnico di Torino, Italy.
    Dynamic model with experimental validation of a biogas-fed SOFC plant2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 135, p. 21-34Article in journal (Refereed)
    Abstract [en]

    The dynamic model of a poly-generation system based on a biogas-fed solid oxide fuel cell (SOFC) plant is presented in this paper. The poly-generation plant was developed in the framework of the FP7 EU-funded project SOFCOM (www.sofcom.eu), which consists of a fuel-cell based polygeneration plant with CO2 capture and re-use. CO2 is recovered from the anode exhaust of the SOFC (after oxy-combustion, cooling and water condensation) and the Carbon is fixed in the form of micro-algae in a tubular photobioreactor. This work focuses on the dynamic operation of the SOFC module running on steam-reformed biogas. Both steady state and dynamic operation of the fuel cell stack and the related Balance-of-Plant (BoP) has been modeled in order to simulate the thermal behavior and performance of the system. The model was validated against experimental data gathered during the operation of the SOFCOM proof-of-concept showing good agreement with the experimental data. The validated model has been used to investigate further on the harsh off-design operation of the proof-of-concept. Simulation results provide guidelines for an improved design of the control system of the plant, highlighting the feasible operating region under safe conditions and means to maximize the overall system efficiency.

  • 6. de Carvalho, Danila Morais
    et al.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    de Queiroz, Jose Humberto
    Colodette, Jorge Luiz
    Cold alkaline extraction as a pretreatment for bioethanol production from eucalyptus, sugarcane bagasse and sugarcane straw2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 124, p. 315-324Article in journal (Refereed)
    Abstract [en]

    Optimal conditions for the cold alkaline extraction (CAE) pretreatment of eucalyptus, sugarcane bagasse and sugarcane straw are proposed in view of their subsequent bioconversion into ethanol through the semi -simultaneous saccharification and fermentation (SSSF) process (with presaccharification followed by simultaneous saccharification and fermentation, or SSF). The optimum conditions, which are identified based on an experiment with a factorial central composite design, resulted in the removal of 46%, 52% and 61% of the xylan and 15%, 37% and 45% of the lignin for eucalyptus, bagasse and straw, respectively. The formation of pseudo-extractives was observed during the CAE of eucalyptus. Despite the similar glucose concentration and yield for all biomasses after 12 h of presaccharification, the highest yield (0.065 g(ethanol)/g(biomass)), concentrations (5.74 g L-1) and volumetric productivity for ethanol (0.57 g L-1 h(-1)) were observed for the sugarcane straw. This finding was most likely related to the improved accessibility of cellulose that resulted from the removal of the largest amount of xylan and lignin.

  • 7.
    Fakhrai, Reza
    et al.
    KTH, Superseded Departments, Metallurgy. KTH, Superseded Departments, Materials Science and Engineering.
    Blasiak, Wlodzimierz
    KTH, Superseded Departments, Materials Science and Engineering.
    Combustion Performance of the Kraft Recovery Boiler Versus Black Liquor PropertiesIn: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227Article in journal (Other academic)
  • 8.
    Fakhrai, Reza
    et al.
    KTH, Superseded Departments, Metallurgy.
    Blasiak, Wlodzimierz
    Theoretical Analysis of Interaction Between Fuel Drop and Walls during Black Liquor Combustion in a Kraft Recovery Furnace2001In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227Article in journal (Other academic)
  • 9. Fiaschi, D
    et al.
    Gamberi, F
    Bartlett, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Griffin, T
    The air membrane-ATR integrated gas turbine power cycle: A method for producing electricity with low CO2 emissions2005In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 46, no 15-16, p. 2514-2529Article in journal (Refereed)
    Abstract [en]

    The air membrane-auto thermal reforming (AM-ATR) gas turbine cycle combines features of the R-ATR power cycle, introduced at the University of Florence, with ceramic, air separation membranes to achieve a novel combined cycle process with fuel decarbonisation and near-zero CO2 emissions. Within this process, the natural gas fuel is converted to H-2 and CO through the auto thermal reforming process (ATR), i.e. combined partial oxidation and steam methane reforming, within the air separation membrane reactor. In a subsequent process unit, the H-2 Content of the reformed fuel is enriched by the well known CO-CO2 shift reaction. This fuel is then sent to an amine based carbon dioxide removal unit and, finally, to two combustors: the first one is located upstream of the membrane reformer (in order to achieve the required working temperature) and the second one is downstream of the membrane to reach the desired turbine inlet temperature (TIT). The main advantage of the proposed concept over other decarbonisation processes is the coupling of the membrane and the ATR reactor. This coupling greatly reduces the mass flow of syngas with respect to the air blown ATR contained in the previously proposed R-ATR, thus lowering the size of the syngas treatment section. Furthermore, as the oxygen production is integrated at high temperatures in the power cycle, the efficiency penalty of producing oxygen is much smaller than for the traditional cryogenic oxygen separation. The main advantages over other integrated GT-membrane concepts are the lower membrane operating temperature, lower levels of required air separation at high partial pressure driving forces (leading to lower membrane surface areas) and the possibility to achieve a higher TIT with top firing without increasing CO2 emissions. When compared to power plants with tail end CO2 separation, the CO2 removal process treats a gas at pressure and with a significantly higher CO2 concentration than that of gas turbine exhausts, which allows a compact carbon dioxide removal unit with a lower energy penalty. Starting from the same basis, various configurations were considered and optimised, all of which targeted a 65 MW power output combined cycle. The efficiency level achieved is around 45% (including recompression of the separated CO2), which is roughly 10% less than the reference GT-CC plant (without CO2 removal). A significant part of the efficiency penalty (4.3-5.6% points) is due to the fuel reforming, whereas further penalties come from the recompression units, loss of working fluid through the expander and the steam extracted for the ATR reactor and CO2 separation. The specific CO2 emissions of the MCM-ATR are about 120 kg CO2/kWh, representing 30% of the emissions without CO2 removal. This may be reduced to 10-15% with a better design of the shift reactors and the CO2 removal unit. Compared to other concepts with air membrane technology, such as the AZEP concept, the efficiency loss is much greater when used for fuel de-carbonisation than for previous integration options.

  • 10.
    Fuso Nerini, Francesco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Valentini, Francesco
    Modi, Anish
    Upadhyay, Govinda
    Abeysekera, Muditha
    Salehin, Sayedus
    Appleyard, Eduardo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    The Energy and Water Emergency Module: A containerized solution for meeting the energy and water needs in protracted displacement situations2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 93, p. 205-214Article in journal (Refereed)
    Abstract [en]

    The world has faced many natural and man-made disasters in the past few years, resulting in millions of people living in temporary camps across the globe. The energy and clean water needs of the relief operators in such emergency situations are primarily satisfied by diesel engine based generators and importing clean water to the site, in certain cases even for several years after the emergency. This approach results in problems such as low security of supply and high costs. Especially targeting the prolonged displacement situations, this paper presents an alternative solution - the Energy and Water Emergency Module. The proposed solution aims towards reducing the dependency on fossil fuel in prolonged emergency situations to a minimum while including local energy sources in the energy supply in a flexible and reliable way. The proposed module is built in a standard 20 ft container, and encompasses hybrid generation from solar, wind and biomass, with the possibility of using fossil sources too thanks to a dual fuel gas engine. The module can work both in grid connected and stand-alone mode. In addition the module includes a water purification unit to meet the water needs of displaced population. A demonstration unit was assembled at the Royal Institute of Technology in Stockholm during the year 2012 as a 'concept proof, and is now being tested and optimized for future deployment on the field. Preliminary testing and modelling shows that the proposed solution can reliably support emergency situations, and is already cost competitive with the current water and energy supply solutions for emergency situations.

  • 11.
    Ghaem Sigarchian, Sara
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    The choice of operating strategy for a complex polygeneration system: A case study for a residential building in Italy2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 163, p. 278-291Article in journal (Refereed)
    Abstract [en]

    The operating strategy can affect the optimal solution and performance of a polygeneration energy system. In this study, the effect of operating strategies: following thermal load; following electric load; and modified base load on the optimal solution of a polygeneration system for a residential building complex in the northern part of Italy is investigated. For the optimal solutions, a comparative analysis is carried out considering the techno-economic and environmental performance of the system. The result elaborates on how the benefits achieved in a polygeneration system are influenced by the choice of operating strategy. In the building complex, implementation of the operating strategies shows considerable energetic, economic and environmental benefits compared to conventional separate heat and power generation. The ranges of annualized total cost reduction of 17-19%, carbon dioxide emission reduction of 35-43% and fuel consumption reduction of 30-38% are achieved for the various operating strategies. However, each of the operating strategies has its own advantages and drawbacks which emphasizes the importance of post-processing of the results in order to make the right choice. For example, the following thermal load shows the advantage of a higher carbon dioxide emission reduction. On the other hand, one drawback is its lower self-sustainability in terms of electric power compared to the other strategies.

  • 12.
    Ghaem Sigarchian, Sara
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    The choice of operating strategy for a complex polygeneration system: A case study for a residential building in Italy2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 163, p. 278-291Article in journal (Refereed)
    Abstract [en]

    The operating strategy can affect the optimal solution and performance of a polygeneration energy system. In this study, the effect of operating strategies: following thermal load; following electric load; and modified baseload on the optimal solution of a polygeneration system for a residential building complex in the northern part of Italy is investigated. For the optimal solutions, a comparative analysis is carried out considering the techno-economic and environmental performance of the system. The result elaborates on how the benefits achieved in a polygeneration system are influenced by the choice of operating strategy. In the building complex, implementation of the operating strategies shows considerable energetic, economic and environmental benefits compared to conventional separate heat and power generation. The ranges of annualized total cost reduction of 17–19%, carbon dioxide emission reduction of 35–43% and fuel consumption reduction of 30–38% are achieved for the various operating strategies. However, each of the operating strategies has its own advantages and drawbacks which emphasizes the importance of post-processing of the results in order to make the right choice. For example, the following thermal load shows the advantage of a higher carbon dioxide emission reduction. On the other hand, one drawback is its lower self-sustainability in terms of electric power compared to the other strategies.

  • 13.
    Guan, Tingting
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Chutichai, Bhawasut
    Alvfors, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Arpornwichanop, Amornchai
    Biomass-fuelled PEMFC systems: Evaluation of two conversion pathsrelevant for different raw materials2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 106, p. 1183-1191Article in journal (Refereed)
    Abstract [en]

    Biomass-fuelled polymer electrolyte membrane fuel cells (PEMFCs) offer a solution for replacing fossilfuel with hydrogen production. This paper uses simulation methods for investigating biomass-fuelledPEMFCs for different raw materials and conversion paths. For liquid and solid biomass, anaerobic diges-tion (AD) and gasification (GF), respectively, are relatively viable and developed conversion technologies.Therefore, the AD-PEMFC system and the GF-PEMFC system are simulated for residential applications inorder to evaluate the performance of the biomass-fuelled PEMFC systems. The results of the evaluationshow that renewable hydrogen-rich gas from manure or forest residues is usable for the PEMFCs andmakes the fuel cell stack work in a stable manner. For 100 kWe generation, the GF-PEMFC system yieldsan excellent technical performance with a 20% electric efficiency and 57% thermal efficiency, whereas theAD-PEMFC system only has an 9% electric efficiency and 13% thermal efficiency due to the low efficiencyof the anaerobic digester (AD) and the high internal heat consumption of the AD and the steam reformer(SR). Additionally, in this study, the environmental performances of the AD-PEMFC and the GF-PEMFC interms of CO2emission offset and land-use efficiency are discussed.

  • 14. Keshavarzian, Sajjad
    et al.
    Rocco, Matteo V.
    Gardumi, Francesco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Colombo, Emanuela
    Practical approaches for applying thermoeconomic analysis to energy conversion systems: Benchmarking and comparative application2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 150, p. 532-544Article in journal (Refereed)
  • 15.
    Kilkiş, Şiir
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    A net-zero building application and its role in exergy-aware local energy strategies for sustainability2012In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 63, no SI, p. 208-217Article in journal (Refereed)
    Abstract [en]

    Based on two case studies, this paper explores the nexus of exergy, net-zero targets, and sustainable cities as a means of analyzing the role of exergy-aware strategies at the building and district level. The first case study is a premier building in Ankara that is ready to meet the net-zero exergy target. It is also the first building in Turkey to receive the highest Platinum rating in Leadership in Energy and Environmental Design. A net-zero exergy building (NZEXB) is a building that has an annual sum of net-zero exergy transfer across the building-district boundary. This new target is made possible by lowered annual exergy consumption, (AEXC), and increased on-site production from a bundle of sustainable energy technologies. The modeled results of the building indicate that the reduced AEXC of 60 kW h/m 2 yr is met with on-site production of 62 kW h/m 2 yr. On-site production includes PV and building integrated PV, a micro-wind turbine, combined heat and power, GSHP, and solar collectors. Diversified thermal energy storage tanks further facilitate the exergy supply to meet with the exergy demand. The results of this case study provide key lessons to structure an energy value chain that is more aware of exergy, which are up-scalable to the district level when the bundle of sustainable energy technologies is zoomed out across a larger spatial area. These key lessons are then compared with the second case study of two districts in the south heating network of the city of Stockholm, which was the European Green Capital in 2010. The levels of exergy match in these districts of Stockholm, namely the districts of Högdalen and Hammarby, is found to be 0.82 and 0.84, respectively. However, there remain several bottlenecks for these districts to reach net-zero targets at the community level. The paper concludes that the NZEXB case study has much to offer as a "building block" to reform the way energy is converted and managed and in this way, to structure an exergy-aware energy value chain for greater sustainability in green cities of the future.

  • 16.
    Larsson, Mårten
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Görling, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Alvfors, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Bio-methane upgrading of pyrolysis gas from charcoal production2013In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 3, p. 66-73Article in journal (Refereed)
    Abstract [en]

    This article presents a novel route for bio-methane synthesis utilizing pyrolysis gas from charcoal production. It is a retrofit option that may increase overall process efficiency in charcoal production while adding a valuable product. The pyrolysis gas from charcoal production can be used for bio-methane production instead of burning, while the required heat for the charcoal production is supplied by additional biomass. The aim is to evaluate the energy efficiency of bio-methane upgrading from two types of charcoal plants, with and without recovery of liquid by-products (bio-oil). Aspen simulations and calculations of the energy and mass balances are used to analyse the system. The yield of bio-methane compared to the import of additional biomass is estimated to be 81% and 85% (biomass to bio-methane yield) for the syngas case and the pyrolysis vapour case, respectively. When the biomass necessary to produce the needed electricity (assuming ηel = 33%) is included, the yields amount to 65% and 73%. The results show that the suggested process is a competitive production route for methane from lignocellulosic biomass.

  • 17. Lee, Duu-Jong
    et al.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    Chou, Siaw-Kiang
    Desideri, Umberto
    Clean, efficient, affordable and reliable energy for a sustainable future: Preface2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, p. 1-3Article in journal (Other academic)
  • 18.
    Li, Jun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zhang, Xiaolei
    Department of Mechanical Engineering, University of Alberta, Edmonton, Canada.
    Pawlak-Kruczek, Halina
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kruczek, P.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Process simulation of co-firing torrefied biomass in a 220 MWe coal-fired power plant2014In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 84, p. 503-511Article in journal (Refereed)
    Abstract [en]

    Torrefaction based co-firing in a pulverized coal boiler has been proposed for large percentage of biomass co-firing. A 220 MWe pulverized coal-power plant is simulated using Aspen Plus for full understanding the impacts of an additional torrefaction unit on the efficiency of the whole power plant, the studied process includes biomass drying, biomass torrefaction, mill systems, biomass/coal devolatilization and combustion, heat exchanges and power generation. Palm kernel shells (PKS) were torrefied at same residence time but 4 different temperatures, to prepare 4 torrefied biomasses with different degrees of torrefaction. During biomass torrefaction processes, the mass loss properties and released gaseous components have been studied. In addition, process simulations at varying torrefaction degrees and biomass co-firing ratios have been carried out to understand the properties of CO2 emission and electricity efficiency in the studied torrefaction based co-firing power plant. According to the experimental results, the mole fractions of CO2 and CO account for 69-91% and 4-27% in torrefied gases. The predicted results also showed that the electrical efficiency reduced when increasing either torrefaction temperature or substitution ratio of biomass. A deep torrefaction may not be recommended, because the power saved from biomass grinding is less than the heat consumed by the extra torrefaction process, depending on the heat sources.

  • 19.
    Lu, Hai
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Alanne, K.
    Martinac, Ivo
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Energy quality management for building clusters and districts (BCDs) through multi-objective optimization2014In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 79, p. 525-533Article in journal (Refereed)
    Abstract [en]

    Renewable energy systems entail a significant potential to meet the energy requirements of building clusters and districts (BCDs) provided that local energy sources are exploited efficiently. Besides improving the energy efficiency by reducing energy consumption and improving the match between energy supply and demand, energy quality issues have become a key topic of interest. Energy quality management is a technique that aims at optimally utilizing the exergy content of various renewable energy sources. In addition to minimizing life-cycle CO2 emissions related to exergy losses of an energy system, issues such as system reliability should be addressed. The present work contributes to the research by proposing a novel multi-objective design optimization scheme that minimizes the global warming potential during the life-cycle and maximizes the exergy performance, while the maximum allowable level of the loss of power supply probability (LPSP) is predefined by the user as a constraint. The optimization makes use of Genetic Algorithm (GA). Finally, a case study is presented, where the above methodology has been applied to an office BCD located in Norway. The proposed optimization scheme is proven to be efficient in finding the optimal design and can be easily enlarged to encompass more relevant objective functions.

  • 20.
    Lu, Hai
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Service and Energy Systems. Key Laboratory of Efficient Utilization of Low and Medium Grade Energy (Tianjin University), China.
    Yu, Zitao
    Alanne, Kari
    Xu, Xu
    Fan, Liwu
    Yu, Han
    Zhang, Liang
    Martinac, Ivo
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Service and Energy Systems.
    Parametric analysis of energy quality management for district in China using multi-objective optimization approach2014In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 87, p. 636-646Article in journal (Refereed)
    Abstract [en]

    Due to the increasing energy demands and global warming, energy quality management (EQM) for districts has been getting importance over the last few decades. The evaluation of the optimum energy systems for specific districts is an essential part of EQM. This paper presents a deep analysis of the optimum energy systems for a district sited in China. A multi-objective optimization approach based on Genetic Algorithm (GA) is proposed for the analysis. The optimization process aims to search for the suitable 3E (minimum economic cost and environmental burden as well as maximum efficiency) energy systems. Here, life cycle CO2 equivalent (LCCO2), life cycle cost (LCC) and exergy efficiency (EE) are set as optimization objectives. Then, the optimum energy systems for the Chinese case are presented. The final work is to investigate the effects of different energy parameters. The results show the optimum energy systems might vary significantly depending on some parameters.

  • 21. Motahar, Sadegh
    et al.
    Alemrajabi, Ali A.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Experimental study on solidification process of a phase change material containing TiO2 nanoparticles for thermal energy storage2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 138, p. 162-170Article in journal (Refereed)
    Abstract [en]

    The solidification process of n-octadecane as a phase change material (PCM) with dispersed titanium dioxide (TiO2) nanoparticles was experimentally studied. Experiments were performed in a rectangular enclosure cooled from one vertical side corresponding to the solid Stefan numbers in the range 0.17-0.239. The Rayleigh numbers at the initial of experiment were in the range 0.92-18.3 x 10(6). The theological behavior of liquid PCM/TiO2 samples at higher concentrations tended to Bingham fluids, thus the solidification experiments were conducted for Bingham numbers in the range 0-2.17. The solidification process was characterized by visualizing the progression of solid-liquid interface as well as recording the temperature distribution inside the enclosure. Experimental results showed that heat conduction was the dominant mode of heat transfer during the solidification. Dispersing TiO2 nanoparticles led to enhance in thermal conductance and consequently the increase in solidified volume. An increase of 7%, 9% and 18% in solidified volume fraction was observed at the end of solidification for the mass fractions of 1 wt.%, 2 wt.% and 4 wt.%, respectively. A universal correlation was proposed to predict the solidified volume fraction as a function of Fourier number, Rayleigh number, solid Stefan number, Bingham number and mass fraction of nanoparticles with an error below 11%.

  • 22.
    Olsson, Alexander
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Lind, Mårten
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    PV water pumping for carbon sequestration in dry land agriculture2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, p. 169-179Article in journal (Refereed)
    Abstract [en]

    This paper suggests a novel model for analysing carbon sequestration activities in dry land agriculture considering the water-food-energy-climate nexus. The paper is based on our on-going studies on photovoltaic water pumping (PVWP) systems for irrigation of grasslands in China. Two carbon sequestration projects are analysed in terms of their water productivity and carbon sequestration potential. It is concluded that the economic water productivity, i.e. how much water that is needed to produce an amount of grass, of grassland restoration is low and that there is a need to include several of the other co-benefits to justify the use of water for climate change mitigation. The co-benefits are illustrated in a nexus model including (1) climate change mitigation, (2) water availability, (3) downstream water impact, (4) energy security, (5) food security and (6) moisture recycling. We argue for a broad approach when analysing water for carbon sequestration. The model includes energy security and food security together with local and global water concerns. This makes analyses of dry land carbon sequestration activities more relevant and accurate. Without the nexus approach, the co-benefits of grassland restoration tend to be diminished.

  • 23. Salman, C. A.
    et al.
    Naqvi, M.
    Thorin, E.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Malardalens hogskola, Sweden.
    Impact of retrofitting existing combined heat and power plant with polygeneration of biomethane: A comparative techno-economic analysis of integrating different gasifiers2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 152, p. 250-265Article in journal (Refereed)
    Abstract [en]

    It is vital to identify and evaluate the optimal gasifier configuration that could be integrated with existing or new combined heat and power (CHP) plants to maximize the utilization of boiler operating capacity during off-peak hours with minimal effect on the boiler performance. This study aims to identify technically and economically most suitable gasification configuration and the reasonable operational limits of a CHP plant when integrated with different types of gasifiers. The selected gasifiers for the study are, (i) indirectly heated dual fluidized bed gasifier (DFBG), (ii) directly heated circulating fluidized bed gasifier (CFBG), and (iii) entrained flow gasifier (EFG). The gasifiers are selected on their ability to produce high-quality syngas from waste refused derived fuel (RDF). The syngas from the gasifiers is utilized to produce biomethane, whereas the heat and power from the CHP plant are consumed to run the gasification process. A detailed techno-economic analysis is performed using both flexible capacity and fixed capacity gasifiers and integrated with the CHP plant at full load. The results reveal that the integration leads to increase in operating time of the boiler for all gasifier configurations. The indirectly heated DFBG shows the largest biomethane production with less impact on the district heat and power production. Extra heat is available for biomethane production when the district heat and biomethane are prioritized, and the electric power is considered as a secondary product. Furthermore, the economic indicators reflect considerable dependency of integrated gasification performance on variable prices of waste biomass and biomethane.

  • 24.
    Semlitsch, Bernhard
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Wang, Yue
    Northwestern Polytechnical University, China.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Flow effects due to pulsation in an internal combustion engine exhaust port2014In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 86, p. 520-536Article in journal (Refereed)
    Abstract [en]

    In an internal combustion engine, the residual energy remaining after combustion in the exhaust gasses can be partially recovered by a downstream arranged device. The exhaust port represents the passage guiding the exhaust gasses from the combustion chamber to the energy recovering device, e.g. a turbocharger. Thus, energy losses in the course of transmission shall be reduced as much as possible. However, in one-dimensional engine models used for engine design, the exhaust port is reduced to its discharge coefficient, which is commonly measured under constant inflow conditions neglecting engine-like flow pulsation. In this present study, the influence of different boundary conditions on the energy losses and flow development during the exhaust stroke are analyzed numerically regarding two cases, i.e. using simple constant and pulsating boundary conditions. The compressible flow in an exhaust port geometry of a truck engine is investigated using three-dimensional Large Eddy Simulations (LES). The results contrast the importance of applying engine-like boundary conditions in order to estimate accurately the flow induced losses and the discharge coefficient of the exhaust port. The instantaneous flow field alters significantly when pulsating boundary conditions are applied. Thus, the induced losses by the unsteady flow motion and the secondary flow motion are increased with inflow pulsations. The discharge coefficient decreased about 2% with flow pulsation. A modal flow decomposition method, i.e. Proper Orthogonal Decomposition (POD), is used to analyze the coherent structures induced with the particular inflow and outflow conditions. The differences in the flow field for different boundary conditions suggest to incorporate a modeling parameter accounting for the quality of the flow at the turbocharger turbine inlet in one-dimensional simulations.

  • 25.
    Semlitsch, Bernhard
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Mechanics of Industrial Processes. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Wang, Yue
    Northwestern Polytechnical University.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Flow effects due to valve and piston motion in an internal combustion engine exhaust port2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 96, p. 18-30Article in journal (Refereed)
    Abstract [en]

    Performance optimization regarding e.g. exhaust valve strategies in an internal combustion engine is often performed based on one-dimensional simulation investigation. Commonly, a discharge coefficient is used to describe the flow behavior in complex geometries, such as the exhaust port. This discharge coefficient for an exhaust port is obtained by laboratory experiments at fixed valve lifts, room tem- peratures, and low total pressure drops. The present study investigates the consequences of the valve and piston motion onto the energy losses and the discharge coefficient. Therefore, Large Eddy Simulations are performed in a realistic internal combustion geometry using three different modeling strategies, i.e. fixed valve lift and fixed piston, moving piston and fixed valve lift, and moving piston and moving valve, to estimate the energy losses. The differences in the flow field development with the different modeling approaches is delineated and the dynamic effects onto the primary quantities, e.g. discharge coefficient, are quantified. Considering the motion of piston and valves leads to negative total pressure losses during the exhaust cycle, which cannot be observed at fixed valve lifts. Additionally, the induced flow structures develop differently when valve motion is taken into consideration, which leads to a significant disparity of mass flow rates evolving through the two individual valve ports. However, accounting for piston motion and limited valve motion, leads to a minor discharge coefficient alteration of about one to two percent. 

  • 26.
    Siyal, Shahid Hussain
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Mentis, Dimitris
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Howells, Mark I.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Mapping key economic indicators of onshore wind energy in Sweden by using a geospatial methodology2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 128, p. 211-226Article in journal (Refereed)
    Abstract [en]

    Due to modern advancements in renewable energy systems and increasing prices of fossil fuels wind energy is getting a lot of attention all over the world. In this regard, Sweden also fixed motivated targets to get energy supply from local renewable energy resources. So, local wind power could help the country in achieving the targets. In this study, economic indicators of wind energy were spatially estimated for Sweden by using ArcGIS tool. In order to do this, as input data one-year high resolution modeled annual average wind data was processed by means of Rayleigh distribution, wind turbine power curve, land use constraints, technical constraints and economic parameters. Based on the input data, it was concluded that Sweden possesses economically feasible wind energy resource. The results of the study indicate that southern and central regions could produce economically viable wind electricity in all aspects as compared to the northern region of the country. Lastly, it was recommended to speed up wind energy penetration in Sweden, communal awareness and acceptance regarding the resource should be increased to avoid possible misunderstanding. Additionally, the capability of the national electric grid should be enhanced to take up the large scale unpredictable wind energy resource.

  • 27.
    Sommerfeldt, Nelson
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Madani, Hatef
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    On the use of hourly pricing in techno-economic analyses for solar photovoltaic systems2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, no SI, p. 180-189Article in journal (Refereed)
    Abstract [en]

    The use of hourly prices in distributed photovoltaic (PV) techno-economic analysis is rare, but may become necessary as time-of-day retail pricing becomes more common. A methodology is presented for selecting an hourly price curve suitable for long-term analysis, called the typical price year (TPY), which is based on the methodology for TMY weather data. Using a techno-economic analysis with annual revenues and net present value as indicators, a TPY curve for the Swedish market is validated and then compared to 18 price simplification methods to determine the error introduced by the use of non-hourly prices. Results show that the TPY method produces a curve which accurately represents long term pricing trends, but using a static annual mean introduces minor revenue errors of 1.3%. This suggests the TPY may not be necessary in the Swedish market, but further analysis of the method is suggested for other markets.

  • 28.
    Tan, Yuting
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Nookuea, Worrada
    Li, Hailong
    Thorin, Eva
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    Property impacts on Carbon Capture and Storage (CCS) processes: A review2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 118, p. 204-222Article in journal (Refereed)
    Abstract [en]

    The knowledge of thermodynamic and transport properties of CO2-mixtures is important for designing and operating different processes in carbon capture and storage systems. A literature survey was conducted to review the impact of uncertainty in thermos-physical properties on the design and operation of components and processes involved in CO2 capture, conditioning, transport and storage. According to the existing studies on property impacts, liquid phase viscosity and diffusivity as well as gas phase diffusivity significantly impact the process simulation and absorber design for chemical absorption. Moreover, the phase equilibrium is important for regenerating energy estimation. For CO2 compression and pumping processes, thermos-physical properties have more obvious impacts on pumps than on compressors. Heat capacity, density, enthalpy and entropy are the most important properties in the pumping process, whereas the compression process is more sensitive to heat capacity and compressibility. In the condensation and liquefaction process, the impacts of density, enthalpy and entropy are low on heat exchangers. For the transport process, existing studies mainly focused on property impacts on the performance of pipeline steady flow processes. Among the properties, density and heat capacity are most important. In the storage process, density and viscosity have received the most attention in property impact studies and were regarded as the most important properties in terms of storage capacity and enhanced oil recovery rate. However, for physical absorption, physical adsorption and membrane separation, there has been a knowledge gap about the property impact. In addition, due to the lack of experimental data and process complexity, little information is available about the influence of liquid phase properties on the design of the absorber and desorber for chemical absorption process. In the CO2 conditioning process, knowledge of the impacts of properties beyond density and enthalpy is insufficient. In the transport process, greater attention should focus on property impacts on transient transport processes and ship transport systems. In the storage process, additional research is required on the dispersion process in enhanced oil recovery and the dissolution process in ocean and saline aquifer storage.

  • 29. Vadiee, Amir
    et al.
    Yaghoubi, Mahmoud
    Sardella, Marco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Farjam, Pardis
    Energy analysis of fuel cell system for commercial greenhouse application: A feasibility study2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 89, p. 925-932Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to investigate the feasibility of integrating a proton exchange membrane fuel cell (PEMFC) system with a commercial greenhouse and assess the mutual benefits of such integration. The main objective is to recover the low quality waste heat of the PEMFC system in order to meet the thermal energy demand of a commercial greenhouse. In addition the PEMFC covers the some part of the greenhouse electrical demand. In this study an energy analysis has been performed in order to evaluate the energetic performance of the system. To achieve these aims, first, a system model has been developed using TRNSYS. Afterwards, a sensitivity analysis has been carried out varying the main influencing operating parameters in order to evaluate an optimal configuration of the system. In particular the influences of temperature and air stoichiometry have been investigated. The results show that a 3 kW fuel cell system is capable to cover approximately the 25% and 10% of the usual electricity and heat demands of a 1000 m(2) commercial greenhouse during a year, respectively.

  • 30.
    Wang, Chuan
    et al.
    Swerea MEFOS.
    Mellin, Pelle
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Lövgren, Jonas
    SSAB Europe.
    Nilsson, Leif
    SSAB Europe.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Salman, Hassan
    Sveaskog.
    Hultgren, Anders
    SCA Energy.
    Larsson, Mikael
    Luleå University of Technology.
    Biomass as blast furnace injectant: Considering availability, pretreatment and deployment in the Swedish steel industry2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, no SI, p. 217-226Article in journal (Refereed)
    Abstract [en]

    We have investigated and modeled the injection of biomass into blast furnaces (BF), in place of pulverized coal (PC) from fossil sources. This is the easiest way to reduce CO2 emissions, beyond efficiency improvements. The considered biomass is either pelletized, torrefied or pyrolyzed. It gives us three cases where we have calculated the maximum replacement ratio for each. It was found that charcoal from pyrolysis can fully replace PC, while torrefied material and pelletized wood can replace 22.8% and 20.0% respectively, by weight. Our energy and mass balance model (MASMOD), with metallurgical sub-models for each zone, further indicates that (1) more Blast Furnace Gas (BFG) will be generated resulting in reduced fuel consumption in an integrated plant, (2) lower need of limestone can be expected, (3) lower amount of generated slag as well, and (4) reduced fuel consumption for heating the hot blast is anticipated. Overall, substantial energy savings are possible, which is one of the main findings in this paper. Due to the high usage of PC in Sweden, large amounts of biomass is required if full substitution by charcoal is pursued (6.19 TWh/y). But according to our study, it is likely available in the long term for the blast furnace designated M3 (located in Luleå). Finally, over a year with almost fully used production capacity (2008 used as reference), a 28.1% reduction in on-site emissions is possible by using charcoal. Torrefied material and wood pellets can reduce the emissions by 6.4% and 5.7% respectively. The complete replacement of PC in BF M3 can reduce 17.3% of the total emissions from the Swedish steel industry.

  • 31. Wang, F.
    et al.
    Deng, S.
    Zhao, J.
    Yang, G.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Integrating geothermal into coal-fired power plant with carbon capture: A comparative study with solar energy2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 148, p. 569-582Article in journal (Refereed)
    Abstract [en]

    A new system integrating geothermal energy into post-combustion carbon capture is proposed in this paper. Geothermal energy at medium temperatures is used to provide the required thermal heat for solvent regeneration. The performance of this system is compared with solar assisted carbon capture plant via technical and economic evaluation. A 300 MWe coal-fired power plant is selected as the reference case, and two different locations based on the local climatic conditions and geothermal resources are chosen for the comparison. The results show that the geothermal assisted post-combustion carbon capture plant has better performances than the solar assisted one in term of the net power output and annual electricity generation. The net plant average efficiency based on lower heating value can be increased by 2.75% with a thermal load fraction of about 41%. Results of economic assessment show that the proposed geothermal assisted post-combustion carbon capture system has lower levelized costs of electricity and cost of carbon dioxide avoidance compared to the solar assisted post-combustion carbon capture plant. In order to achieve comparative advantages over the reference post-combustion carbon capture plant in both locations, the price of solar collector has to be lower than 70 USD/m2, and the drilling depth of the geothermal well shall be less than 2.1 km.

  • 32. Wang, Fu
    et al.
    Li, Hailong
    Zhao, Jun
    Deng, Shuai
    Yan, Jinyue
    Tianjin University, Ministry of Education of China, China.
    Technical and economic analysis of integrating low-medium temperature solar energy into power plant2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 112, p. 459-469Article in journal (Refereed)
    Abstract [en]

    In order to mitigate CO2 emission and improve the efficiency of the utilization of solar thermal energy (STE), solar thermal energy is proposed to be integrated into a power plant. In this paper, seven configurations were studied regarding the integration of STE. A 300 MWe subcritical coal-fired plant was selected as the reference, chemical absorption using monoethanolamine solvent was employed for CO2 capture, and parabolic trough collectors and evacuated tube collectors were used for STE collection. Both technical analysis and economic evaluation were conducted. Results show that integrating solar energy with post-combustion CO2 capture can effectively increase power generation and reduce the electrical efficiency penalty caused by CO2 capture. Among the different configurations, Config-2 and Config6, which use medium temperature STE to replace high pressure feedwater without and with CO2 capture, show the highest net incremental solar efficiency. When building new plants, integrating solar energy can effectively reduce the levelized cost of electricity (LCOE). The lowest LCOE, 99.28 USD/MWh, results from Config-6, with a parabolic trough collector price of 185 USD/m(2). When retrofitting existing power plants, Config-6 also shows the highest net present value (NPV), while Config-2 has the shortest payback time at a carbon tax of 50 USD/ton CO2. In addition, both LCOE and NPV/payback time are clearly affected by the relative solar load fraction, the price of solar thermal collectors and the carbon tax. Comparatively, the carbon tax can affect the configurations with CO2 capture more clearly than those without CO2 capture. 

  • 33. Wang, Tongcai
    et al.
    Luan, Weiling
    Liu, Tongjun
    Tu, Shan-Tung
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Performance enhancement of thermoelectric waste heat recovery system by using metal foam inserts2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 124, p. 13-19Article in journal (Refereed)
    Abstract [en]

    This paper proposed a type of metal foams filled thermoelectric generator (TEG) for waste heat recovery. Metal foam inserts of three kinds of pore densities (5 PPI, 10 PPI and 20 PPI) were included, considering the heat transfer enhancing features of porous metal mediums. A flow channel detachable prototype was designed to experimentally investigate the influence of metal foams on the performance of thermoelectric waste heat recovery (TWHR) system. The operating parameters were further experimented to improve the thermoelectric power generation efficiency, including hot air inlet temperature, cold water flow rate, metal foam pore density and thermoelectric module (TEM) connecting mode. Moreover, the TWHR performance of the system was evaluated on power generation efficiency, heat exchange effectiveness and waste heat recovery rate, respectively. The results showed that filling metal foams in the flow channels could effectively enhance the performance of the TWHR system. The maximum power generation efficiency was 2.05%, when the TEG was filled with 5 PPI metal foams. It was 29.75% higher than the value of unfilled TEG.

  • 34.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Transient performance of an impinging receiver: An indoor experimental study2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 158, p. 193-200Article in journal (Refereed)
    Abstract [en]

    The impinging receiver is a new member of the cavity solar receiver family. In this paper, the transient performance of a prototype impinging receiver has been studied with the help of a Fresnel lens based solar simulator and an externally fired micro gas turbine. The impinging receiver can offer an air outlet temperature of 810 °C at an absorber temperature of 960 °C. The radiative-to-thermal efficiency is measured to be 74.1%. The absorber temperature uniformity is good but high temperature differences have been detected during the ‘cold startup’ process. The temperature changing rate of the receiver is within 3 °C/s for the startup process and 4 °C/s for the shut-down process. In order to avoid quenching effects caused by the impinging jets, the micro gas turbine should be turned off to stop the airflow when the radiative power is off. 

  • 35.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Comparison of potential control strategies for an impinging receiver based dish-Brayton system when the solar irradiation exceeds its design value2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 169, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Potential control strategies for an impinging receiver based dish-Brayton system have been presented for protecting the key components from the risks of overheating when the solar irradiation exceeds its design value. Two of them are selected for a detailed study: changing the effective diameter of the shading device and changing the inlet temperature. A rope-pulley shading device is developed for controlling the shading area in the center of the dish, and the change of the inlet temperature is achieved by applying a bypass at the cold side of the recuperator for reducing the heat transfer rate. Both control strategies can manage the peak temperature on the absorber surface within 1030 °C with an outlet temperature fluctuation between −4.1 and 15.1 °C, so that the impinging receiver can work for long time at any solar direct normal irradiance value. Furthermore, the temperature differences on the absorber surface are between 137.1 °C and 163.8 °C. The cases that are achieved by changing the shield effective diameter are significantly lower (11–26 °C) than the corresponding cases that are achieved by changing the inlet temperature.

  • 36.
    Wilson, Lugano
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    John, Geoffrey R.
    Mhilu, Guthbert F.
    Thermal characterization of tropical biomass feedstocks2011In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 52, no 1, p. 191-198Article in journal (Refereed)
    Abstract [en]

    The processing of agricultural crops results in waste, which is a potential energy resource for alleviating commercial energy supply problems to agricultural-led economies like Tanzania. The energy content of the individual agricultural waste is largely dependent on its chemical composition (C, H and O) and it is negatively affected by the inclusion of inorganic elements and moisture. In this work, fifteen tropical agricultural wastes emanating from export crops for Tanzania were analyzed. The methods used to analyze involved performing proximate and ultimate analysis for determining the biomass composition. Thermal degradation characteristic was established to five selected wastes (coffee husks, sisal bole, cashew nut shells, palm stem, and bagasse) using a thermogravimetric analyzer type NETZSCH STA 409 PC Luxx at a heating rate of 10 K/min. On the basis of elemental composition, the palm fibre and cashew nut shells exhibited high energy content due to their higher H:C ratio with relatively low O:C ratio. Results of the thermal degradation characteristic study showed that the cashew nut shells were the most reactive feedstocks due to their highest overall mass loss and lowest burnout temperatures of 364 °C. Further, kinetic studies done to the five tropical biomass feedstocks under the pseudo single-component overall model established the activation energy for the bagasse, palm stem, and cashew nut shells to be 460 kJ/mole, 542 kJ/mole, and 293 kJ/mole, respectively. The respective activation energies for coffee husks and sisal bole were 370 kJ/mole and 239 kJ/mole. With the exception of the sisal bole, which exhibited zero order reaction mechanism, the remaining materials´ reaction mechanism was of first order. These experimental findings form a basis for ranking these materials for energy generation and provide necessary input to equipment and process designers.

  • 37. Yang, X.
    et al.
    Zheng, N.
    Zhao, L.
    Deng, S.
    Li, Hailong
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Yu, Z.
    Analysis of a novel combined power and ejector-refrigeration cycle2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 108, p. 266-274Article in journal (Refereed)
    Abstract [en]

    A novel combined power and ejector-refrigeration cycle using zeotropic mixture is proposed. In the combined cycle, the turbine exhaust from the organic Rankine cycle entrains the vapor from the ejector-refrigeration cycle. And the zeotropic mixture is divided into the power cycle and the ejector-refrigeration cycle through a vapor-liquid separator. And these two flows have different composition. The cycle performance with different fluid composition is evaluated and it is compared with a conventional combined cycle. It is found that the cycle exergy achieves a maximum value of 10.29% with mixture isobutane/pentane (40%/60%), and the thermal efficiency gets a maximum value of 10.77% with mixture isobutane/pentane (70%/30%). The temperature glide in the evaporator achieves a maximum value of 15.09 K with mixture isobutane/pentane (80%/20%). The parametric analysis shows that the cycle performs better in lower condenser temperature. Though the refrigeration cycle achieves lower evaporating temperature in higher generating temperature, the power output is reduced.

  • 38.
    Zhang, Chi
    et al.
    KTH, School of Chemical Science and Engineering (CHE). Ningbo RX New Materials Technology Co., China.
    Campana, P. E.
    Yang, Jin
    KTH, School of Chemical Science and Engineering (CHE). Ningbo RX New Materials Technology Co., China; China University of Geosciences, China.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Economic performance of photovoltaic water pumping systems with business model innovation in China2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 133, p. 498-510Article in journal (Refereed)
    Abstract [en]

    Expansion by photovoltaic (PV) technologies in the renewable energy market requires exploring added value integrated with business model innovation. In recent years, a pilot trial of PV water pumping (PVWP) technologies for the conservation of grassland and farmland has been conducted in China. In this paper, we studied the added value of the PVWP technologies with an emphasis on the integration of the value proposition with the operation system and customer segmentation. Using the widely used existing PV business models (PV-roof) as a reference, we evaluated discounted cash flow (DCF) and net present value (NPV) under the scenarios of traditional PV roof, PVWP pilot, PVWP scale-up, and PVWP social network, where further added value via social network was included in the business model. The results show that the integrated PVWP system with social network products significantly improves the performance in areas such as the discounted payback period, internal rate of return (IRR), and return on investment (ROI). We conclude that scenario PVWP social network with business model innovation, can result in value add-ins, new sources of revenue, and market incentives. The paper also suggests that current policy incentives for PV industry are not efficient due to a limited source of revenue, and complex procedures of feed-in tariff verification.

  • 39. Zhang, Xiaojing
    et al.
    Yan, Jinying
    Li, Hailong
    Chekani, Shabnam
    KTH.
    Liu, Longcheng
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Investigation of thermal integration between biogas production and upgrading2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, p. 131-139Article in journal (Refereed)
    Abstract [en]

    Thermal integration of anaerobic digestion (AD) biogas production with amine-based chemical absorption biogas upgrading has been studied to improve the overall efficiency of the intergraded system. The thermal characteristics have been investigated for industrial AD raw biogas production and amine-based chemical absorption biogas upgrading. The investigation provides a basic understanding for the possibilities of energy saving through thermal integration. The thermal integration is carried out through well-defined cases based on the thermal characteristics of the biogas production and the biogas upgrading. The following factors are taken into account in the case study: thermal conditions of sub-systems, material and energy balances, cost issues and main benefits. The potential of heat recovery has been evaluated to utilise the waste heat from amine-based upgrading process for the use in the AD biogas production. The results show that the thermal integration has positive effects on improving the overall energy efficiency of the integrated biogas plant. Cost analysis shows that the thermal integration is economically feasible.

  • 40.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Ningbo RK Solar Tech. Ltd., China.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Västerås, Sweden.
    Campana, P. E.
    Benavente, F.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Battery sizing and rule-based operation of grid-connected photovoltaic-battery system: A case study in Sweden2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 133, p. 249-263Article in journal (Refereed)
    Abstract [en]

    The optimal components design for grid-connected photovoltaic-battery systems should be determined with consideration of system operation. This study proposes a method to simultaneously optimize the battery capacity and rule-based operation strategy. The investigated photovoltaic-battery system is modeled using single diode photovoltaic model and Improved Shepherd battery model. Three rule-based operation strategies—including the conventional operation strategy, the dynamic price load shifting strategy, and the hybrid operation strategy—are designed and evaluated. The rule-based operation strategies introduce different operation parameters to run the system operation. multi-objective Genetic Algorithm is employed to optimize the decisional variables, including battery capacity and operation parameters, towards maximizing the system's Self Sufficiency Ratio and Net Present Value. The results indicate that employing battery with the conventional operation strategy is not profitable, although it increases Self Sufficiency Ratio. The dynamic price load shifting strategy has similar performance with the conventional operation strategy because the electricity price variation is not large enough. The proposed hybrid operation strategy outperforms other investigated strategies. When the battery capacity is lower than 72 kW h, Self Sufficiency Ratio and Net Present Value increase simultaneously with the battery capacity.

  • 41. Zhao, Ruikai
    et al.
    Deng, Shuai
    Zhao, Li
    Liu, Yinan
    Tan, Yuting
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Energy-saving pathway exploration of CCS integrated with solar energy: Literature research and comparative analysis2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, p. 66-80Article in journal (Refereed)
    Abstract [en]

    One of main technical barriers to a large-scale application of carbon capture and storage (CCS) technology is a significant amount of required energy, e.g., regeneration heat of solvent in the chemical absorption system. Thus, energy consumption and corresponding high operation cost become two primary challenges for the promotion of CCS technology. Meanwhile, energy from the solar source in various forms has already been successfully used as an effective alternative supply in the industrial section for drying, heating and even cooling. Thus, integrating solar energy utilization into the CCS process could be a reasonable option for a sustainable development. A comparative analysis of CCS integrated with solar energy was presented in this paper based on the existing researches. The current status on typical configuration structure, feature and energy-efficiency performance of integrating options is reviewed for post-combustion, pre-combustion and oxygen-combustion systems. Based on these typical CO2 capture systems, a theoretical analysis is conducted for an energy-efficient comparison. Then four typical structures of the post-combustion system, which are highlighted in the review, are chosen as comparative objects for energy-saving and techno-economic evaluation. The results show that systems with a solar-assisted thermal energy and power generation have comparative advantages in term of carbon emission intensity, but the economic cost is increased under the current conditions of the equipment price. Compared to that of baseline case, carbon emission intensity of the case integrated with solar Organic Rankine Cycle can be reduced with a maximum decline of 9.73%, meanwhile the levelized costs of electricity increases 0.01 USD/kW h correspondingly.

  • 42. Zheng, H.
    et al.
    Wang, C.
    Liu, Qingming
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. Guangdong University of Technology, China.
    Tian, Z.
    Fan, X.
    Thermal performance of copper foam/paraffin composite phase change material2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 157, p. 372-381Article in journal (Refereed)
    Abstract [en]

    Phase change materials are promising options for thermal energy storage and thermal energy devices. However, their low thermal conductivity lowers their charging and discharging rate. In this paper, copper foam was utilized to enhance the thermal performance of the paraffin. A visible experimental device was built to investigate the melting behavior of paraffin with and without copper foam. The effect of the heating position on the thermal performance of copper foam/paraffin composite phase change material (CPCM) was also discussed. The heat transfer characteristics including solid-liquid interface development, temperature distribution and wall temperature of the heater were tested and recorded. In addition, a numerical model was established using one-temperature volume averaging method to analyze the melting process of the CPCM. The experimental results showed that the total melting time of the CPCM was 20.5% shorter than that of pure paraffin, and the CPCM heated at the top melted slowest and reached the biggest temperature difference in the three heating conditions, so the effect of natural convection on the melting process of the CPCM could not be neglected. A two dimensional numerical simulation was also performed to analyze the melting behavior of CPCM, and the numerical results were well consistent with the experimental data.

1 - 42 of 42
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