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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.

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  • 2.
    Ayele, Getnet Tadesse
    et al.
    Bahir Dar Univ, Fac Elect & Comp Engn, Bahir Dar Inst Technol, POB 26, Bahir Dar, Ethiopia..
    Mabrouk, Mohamed Tahar
    IMT Atlantique, GEPEA, UMR CNRS 6144, F-44307 Nantes, France..
    Haurant, Pierrick
    IMT Atlantique, GEPEA, UMR CNRS 6144, F-44307 Nantes, France..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lacarriere, Bruno
    IMT Atlantique, GEPEA, UMR CNRS 6144, F-44307 Nantes, France..
    Optimal heat and electric power flows in the presence of intermittent renewable source, heat storage and variable grid electricity tariff2021In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 243, article id 114430Article in journal (Refereed)
    Abstract [en]

    To decarbonize and increase the flexibility in the heating and electricity sectors, large heat pumps, combined heat and power plants, renewables and storage technologies are increasingly being installed. This results in a tighter coupling between the electricity and heat distribution networks. Hence, the two networks need to be operated in an integrated way so that their synergies can be exploited. The main challenge in that regard is the lack of suitable tools that can capture the detailed operating parameters of both networks simultaneously. This paper proposes a population-based optimal power flow model for integrated heat and electricity distribution networks. An extended energy hub approach is used to model the components of the integrated energy system in a modular form. Active and reactive power balances, heat power balance and optimal management of storage technologies in the presence of intermittent renewables and variable tariffs are considered. The proposed method is then tested using a case study of highly coupled electricity and heat distribution networks consisting of a heat pump, a gas boiler, a combined heat and power plant, a wind turbine and a thermal storage together with a variable electricity tariff. It is found that above 97% of the surplus production from the wind power plant is effectively used in the system and 10.35% of the heat demand is effectively shifted from the peak hours to the cheap-electricity hours. The results show that the proposed method can be used as a decision support tool that can be used for the optimal integration of heat and electricity distribution networks. It also maximizes the synergy that can be captured from the multi-energy systems in general and from the heat and electricity distribution networks in particular.

  • 3.
    Behzadi, Amirmohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Gholamian, Ehsan
    Univ Tabriz, Fac Mech Engn, Tabriz, Iran..
    Alirahmi, Seyed Mojtaba
    Aalborg Univ, Dept Chem & Biosci, DK-6700 Esbjerg, Denmark..
    Nourozi, Behrouz
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Mälardalen Univ, Sch Business Soc & Engn, S-72123 Västerås, Sweden..
    A comparative evaluation of alternative optimization strategies for a novel heliostat-driven hydrogen production/injection system coupled with a vanadium chlorine cycle2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 267, p. 115878-, article id 115878Article in journal (Refereed)
    Abstract [en]

    This paper introduces an innovative and cost-effective multi-generation plant, driven by the central receiverbased concentrated solar systems, to facilitate the desired global green-transition process. The vanadium chlorine thermochemical cycle, which uses hydrogen instead of natural gas in the combustion chamber, is used as an innovative approach for reducing greenhouse gas emissions. The proposed system also includes a thermoelectric generator (TEG) for excess power generation and a multi-effect desalination (MED) unit to reduce exergy loss. The suggested system's technological, economic, and environmental metrics are analyzed and compared to a similar system that stores the created hydrogen rather than burning it in the combustion chamber. Furthermore, the viability of the studied model is investigated under the optimal operating condition, using the example of Sevilla in order to make the conclusions more reliable. According to the findings, the suggested novel configuration is a better alternative in terms of cost and environmental impact owing to decreased product energy costs and CO2 emissions. The outcomes further indicate that the substitution of the condenser with TEG leads to considerably higher power production. According to the optimization findings, the multi-objective grey wolf algorithm is the best optimization strategy compared to the non-dominated genetic and particle swarm approaches. At the best optimization point, 2.5% higher exergy efficiency, 1 $/GJ cheaper product energy cost, and 0.12 kg/kWh lower levelized CO2 emission are achieved compared to the operating condition. The Sankey diagram indicates that the solar heliostat system has the highest irreversibility. The exergy analysis results further reveal that the flue gas condensation process through the Rankine cycle and MED unit lead to a 53.2% reduction in exergy loss. Finally, considerable CO2 emission reductions show that the suggested new method is an effective solution for cleaner energy production in warmer climate countries.

  • 4.
    Behzadi, Amirmohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Mälardalen Univ, Sch Business Soc & Engn, Västerås, Sweden..
    A rule-based energy management strategy for a low-temperature solar/ wind-driven heating system optimized by the machine learning-assisted grey wolf approach2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 277, p. 116590-, article id 116590Article in journal (Refereed)
    Abstract [en]

    This work presents an innovative, practical, and cost-effective solution for advancing state-of-the-art intelligent building energy systems and aiding the intended worldwide green transition with maximum renewable inte-gration. The vanadium chloride cycle, electrolyzer unit, and Alkaline fuel cell are powered by the sun's and wind's energy to produce/store/use hydrogen. A rule-based control scheme is designed to provide a sophisticated interplay between the demand/supply sides, components, and local energy networks to reduce peak capacity, lower emissions, and save energy costs. TRNSYS is used to analyze and compare the techno-economic-environmental indicators of the conventional system and the suggested smart model for a multi-family build-ing in Sweden. A grey wolf method is built in MATLAB with the help of machine learning to determine the optimum operating state with the maximum accuracy and the least amount of computational time. The results reveal that the suggested smart model considerably saves energy and money compared to the conventional system in Sweden while lowering CO2 emissions. According to the optimization results, the grey wolf optimizer and machine learning techniques enable greater total efficiency of 13 %, higher CO2 mitigation of 8 %, a larger cost saving of 38 %, and a reduced levelized energy cost of 41 $/MWh. The scatter distribution of important design parameters shows that altering the fuel cell current and electrode area considerably impacts the system's performance from all angles. The bidirectional connection of the proposed smart system with the heating and electrical networks through the rule-based controller demonstrates that it can supply the building's energy re-quirements for more than 300 days of the year. Eventually, the major contribution of the vanadium chloride cycle in the summer and the electrolyzer in the winter to the creation of hydrogen highlights the significance of renewable hybridization in reducing the dependence of buildings on energy networks.

  • 5.
    Behzadi, Amirmohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Thorin, Eva
    School of Business, Society, and Engineering, Mälardalen University, Västerås, Sweden.
    Duwig, Christophe
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design. School of Business, Society, and Engineering, Mälardalen University, Västerås, Sweden.
    Supply-demand side management of a building energy system driven by solar and biomass in Stockholm: A smart integration with minimal cost and emission2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 292, article id 117420Article in journal (Refereed)
    Abstract [en]

    As part of the transition to a sustainable future, energy-efficient buildings are needed to secure users' comfort and lower the built environment's energy footprint and associated emissions. This article presents a novel, realistic and affordable solution to minimize the footprint of smart building energy systems and enable higher renewable energy use in the building sector. For this, an intelligent system is being developed using a rule-based automation approach that considers thermal comfort, energy prices, meteorological data, and primary energy use. In order to lower the installation cost and part of the environmental footprint, batteries are not used, and the heat pump's size is decreased via component integration. Also, different renewable resources are effectively hybridized using photovoltaic thermal panels and an innovative biomass heater to increase the share of renewable energy, enhance reliability, and shave peak load. In order to secure feasibility, the suggested framework is assessed from the techno-economic and environmental standpoints for 100 residential apartments in Stockholm, Sweden. Our results show that 70.8 MWh of renewable electricity is transferred to the local grid, and the remaining 111.5 MWh is used to supply the building's needs and power the electrically-driven components. The biomass heater meets more than 65% of the space heating demand, mainly at low solar power and high electricity prices, illustrating the value of integration strategies to reduce the system's dependability on the local grid. The results further reveal that most energy purchases during the cloudy days and nights are repaid through the sale of excess renewable production during the warmer hours, with a bidirectional connection with the grid. The monthly energy cost is less than 140 $/MWh for most of the years. The cost can be held low due to the exclusion of batteries and minimizing the heat pump size. The proposed system has a low emission index of 11.9 kgCO2/MWh and can reduce carbon dioxide emissions by 70 TCO2/year compared to using the supply from the Swedish energy mix.

  • 6.
    Bolívar Caballero, José Juan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Han, Tong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Svanberg, Rikard
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Zaini, Ilman Nuran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Yang, Hanmin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Gond, Ritambhara
    Department of Chemistry, Uppsala University, Lägerhyddsvägen 1, 751 21 Uppsala, Sweden, Lägerhyddsvägen 1.
    Cao, Pengcheng
    Kanthal AB, Sörkvarnsvägen 3, 734 27 Hallstahammar, Sweden, Sörkvarnsvägen 3.
    Lewin, Thomas
    Kanthal AB, Sörkvarnsvägen 3, 734 27 Hallstahammar, Sweden, Sörkvarnsvägen 3.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Advanced application of a geometry-enhanced 3D-printed catalytic reformer for syngas production2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 287, article id 117071Article in journal (Refereed)
    Abstract [en]

    Catalyst research on reforming processes for syngas production has mainly focused on the active metals and support materials, while the effect of the catalyst's geometry on the reforming reactions has been poorly studied. The application of 3D-printed materials with enhanced geometries has recently started to be studied in heterogeneous catalysis and is of interest to be implemented for reforming biomass and plastic waste to produce H2-rich syngas. In this study, a geometry-enhanced 3D-printed Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and fabricated. The catalyst was used for batch steam reforming biomass pyrolysis volatiles for syngas production at different parameters (temperature and steam-to-carbon ratio). The results showed complete reforming of pyrolysis volatiles in all experimental cases, a high H2 yield of ≈ 7.6 wt% of biomass was obtained at the optimized steam-to-carbon ratio of 8 and a reforming temperature of 800 °C, which is a higher yield compared to other batch reforming tests reported in the literature. Moreover, CFD simulation results in COMSOL Multiphysics demonstrated that the POCS configuration improves the reforming of pyrolysis volatiles for tar/bio-oil reforming and H2 production thanks to enhanced mass and heat transfer properties compared to the regular monolithic single-channel configuration.

  • 7. Bontemps, Andre
    et al.
    Palm, Björn
    KTH.
    Thonon, Bernard
    Heat transfer in components and systems for sustainable energy technologies: Heat-SET 2005, 5-7 April 2005, Grenoble, France - Foreword2006In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 47, no 20, p. 3509-3509Article in journal (Other academic)
  • 8. Bontemps, Andre
    et al.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Thonon, Bernard
    Heat transfer in components and systems for sustainable energy technologies: Heat-SET 2005, 5-7 April 2005, Grenoble, France - Preface2006In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 47, no 20, p. 3507-3508Article in journal (Other academic)
  • 9. 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.

  • 10.
    Campana, Pietro Elia
    et al.
    Mälardalen Univ, Sch Business Soc & Engn, S-72123 Vastereis, Sweden..
    Cioccolanti, Luca
    Univ Telemat eCampus, Ctr Ric Energia Ambiente & Terr, Novedrate, CO, Italy..
    Francois, Baptiste
    Univ Massachusetts, Dept Civil & Environm Engn, Amherst, MA 01003 USA..
    Jurasz, Jakub
    Mälardalen Univ, Sch Business Soc & Engn, S-72123 Vastereis, Sweden.;AGH Univ Sci & Technol, Fac Management, PL-30059 Krakow, Poland.;Wroclaw Univ Sci & Technol, Fac Environm Engn, PL-50370 Wroclaw, Poland..
    Zhang, Yang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Varini, Maria
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Stridh, Bengt
    Mälardalen Univ, Sch Business Soc & Engn, S-72123 Vastereis, Sweden..
    Yan, Jinyue
    Mälardalen Univ, Sch Business Soc & Engn, S-72123 Vastereis, Sweden..
    Li-ion batteries for peak shaving, price arbitrage, and photovoltaic self-consumption in commercial buildings: A Monte Carlo Analysis2021In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 234, article id 113889Article in journal (Refereed)
    Abstract [en]

    This study investigates the benefits of introducing Li-ion batteries as energy storage unit in the commercial sector by considering a representative building with a photovoltaic system. Only the costs and revenues related to the installation and operation of the battery are considered in this study. The operational strategy of the battery consists in balancing the following processes through day-ahead forecasts for both electricity consumption and photovoltaic production: shaving a targeted peak, performing price arbitrage, and increasing photovoltaic selfconsumption. By reviewing the electricity price cost for commercial buildings from several companies around the world, a general electricity price structure is defined. Afterwards, a Monte Carlo Analysis is applied for three locations with different solar irradiation levels to study the impact of climate, electricity price components, and other seven sensitive parameters on the economic viability of Li-ion batteries. The Monte Carlo Analysis shows that the most sensitive parameters for the net present value are the battery capacity, the battery price, and the component of the electricity price that relates to the peak power consumption. For Stockholm, one of the investigated locations, the corresponding Pearson correlation coefficients are -0.67, -0.66, and 0.19 for the case were no photovoltaic system is installed. For the considered battery operational strategies, the current investment and annual operation costs for the Li-ion battery always lead to negative net present values independently of the location. Battery prices lower than 250 US$/kWh start to manifest positive net present values when combining peak shaving, price arbitrage, and photovoltaic self-consumption. However, the integration of a photovoltaic system leads to a reduced economic viability of the battery by reducing the revenues generated by the battery while performing peak shaving.

  • 11. 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.

  • 12. 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.

  • 13.
    Choque Campero, Luis Antonio
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Univ Mayor San Simon UMSS, Fac Ciencias & Tecnol FCyT, Cochabamba, Bolivia..
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermodynamic and exergetic analyses of a biomass-fired Brayton-Stirling cogeneration cycle for decentralized, rural applications2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 292, article id 117350Article in journal (Refereed)
    Abstract [en]

    Access to electricity in many remote rural areas of the world is wanting and often relies on decentralized concepts that are environmentally detrimental, costly, and unreliable. The purpose of this study was to examine an approach to meet this need that is based on an external biomass-fueled cogeneration system incorporating combined cycles for maximizing efficiency while ensuring robust operation. Specifically, the first and second laws of thermodynamics were analyzed in a system composed of a Brayton-Stirling cycle and a water boiler to compare efficiency, heat and electricity generation under three different power layouts of cogeneration for applications in the range of 100-200 kW electrical power output. The results show that overall efficiency is maximized at 85% with a hybrid power layout for cases where the turbine inlet temperature is 1273 K, the pressure ratio is 0.4, the regenerator effectiveness is 0.95, and the dead volume of the Stirling engine is 0.3. These findings provide a basis for implementing cogeneration systems to improve the reliability and robustness of power systems for rural electrification.

  • 14. 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.

  • 15. 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.

  • 16.
    Ding, Yiyu
    et al.
    Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), Trondheim 7491, Norway.
    Timoudas, Thomas Ohlson
    RISE Research Institutes of Sweden, Sweden.
    Wang, Qian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design. Uponor AB, Hackstavägen 1, Västerås 721 32, Sweden, Hackstavägen 1.
    Chen, Shuqin
    College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China.
    Brattebø, Helge
    Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), Trondheim 7491, Norway.
    Nord, Natasa
    Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), Trondheim 7491, Norway.
    A study on data-driven hybrid heating load prediction methods in low-temperature district heating: An example for nursing homes in Nordic countries2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 269, article id 116163Article in journal (Refereed)
    Abstract [en]

    In the face of green energy initiatives and progressively increasing shares of more energy-efficient buildings, there is a pressing need to transform district heating towards low-temperature district heating. The substantially lowered supply temperature of low-temperature district heating broadens the opportunities and challenges to integrate distributed renewable energy, which requires enhancement on intelligent heating load prediction. Meanwhile, to fulfill the temperature requirements for domestic hot water and space heating, separate energy conversion units on user-side, such as building-sized boosting heat pumps shall be implemented to upgrade the temperature level of the low-temperature district heating network. This study conducted hybrid heating load prediction methods with long-term and short-term prediction, and the main work consisted of four steps: (1) acquisition and processing of district heating data of 20 district heating supplied nursing homes in the Nordic climate (2016–2019); (2) long-term district heating load prediction through linear regression, energy signature curve in hourly resolution, providing an overall view and boundary conditions for the unit sizing; (3) short-term district heating load prediction through two Artificial Neural Network models, f72 and g120, with different prediction input parameters; (4) evaluation of the predicted load profiles based on the measured data. Although the three prediction models met the quality criteria, it was found that including the historical hourly heating loads as the input to the forecasting model enhanced the prediction quality, especially for the peak load and low-mild heating season. Furthermore, a possible application of the heating load profiles was proposed by integrating two building-sized heat pumps in low-temperature district heating, which may be a promising heat supply method in low-temperature district heating.

  • 17.
    Fakhrai, Reza
    et al.
    KTH, Superseded Departments (pre-2005), Metallurgy. KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Blasiak, Wlodzimierz
    KTH, Superseded Departments (pre-2005), 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)
  • 18.
    Fakhrai, Reza
    et al.
    KTH, Superseded Departments (pre-2005), 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)
  • 19. 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.

  • 20.
    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.

  • 21.
    Gao, J. T.
    et al.
    Shanghai Jiao Tong Univ, Inst Refrigerat & Cryogen, Shanghai 200240, Peoples R China..
    Xu, Z. Y.
    Shanghai Jiao Tong Univ, Inst Refrigerat & Cryogen, Shanghai 200240, Peoples R China..
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Su, Chang
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wang, R. Z.
    Shanghai Jiao Tong Univ, Inst Refrigerat & Cryogen, Shanghai 200240, Peoples R China..
    Feasibility and economic analysis of solution transportation absorption system for long-distance thermal transportation under low ambient temperature2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 196, p. 793-806Article in journal (Refereed)
    Abstract [en]

    Sensible heat transportation with water is widely adopted in traditional heating network, which suffers from the low energy transportation density and inevitable heat loss for long-distance heat transportation. To address these two issues, the solution transportation absorption system has been proposed, which transports the thermal energy by stable chemical potential. However, boundary between the two technologies is not clear due to the lack of direct comparison on both technological and economic aspects. In this work, feasibility analysis of the solution transportation absorption system is performed using Aspen plus, and low ambient temperature is considered for a practical scenario. Economic contrast is performed by exergoeconomic analysis. Results show that the coefficient of performance and exergy efficiency of the solution transportation absorption system can reach 0.556 and 24.6% in optimal condition. The energy transportation density is nearly three times higher than that of traditional sensible heat transportation. Moreover, the exergoeconomic analysis indicates that the new system is more economical when the distance exceeds 6 km. It has been proved that the solution transportation absorption system is a feasible and economical way to efficiently transport thermal energy over long distance.

  • 22.
    Ge, Fengua
    et al.
    School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China.
    Wang, Cong
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Exergy analysis of dehumidification systems: A comparison between the condensing dehumidification and the desiccant wheel dehumidification2020In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 224, article id 113343Article in journal (Refereed)
    Abstract [en]

    This paper presents a framework of exergy analysis to evaluate the performance of the condensing dehumidification and the desiccant wheel dehumidification. The performance of two dehumidification methods are compared for pure dehumidification purposes based on proposed dehumidification systems that undertake only the latent load. An air-source heat pump is adopted in the dehumidification systems to serve as the cold and heat source. Based on thermodynamic perfectibility theory and the laboratory experiment of the desiccant wheel, the power requirements and exergy efficiency of the two dehumidification methods are analyzed and compared under 17 sets of operating conditions. The coefficient of performance of the heat pump in the condensing dehumidification system is 2–3 times higher than in conventional air-conditioning systems. Environmental factors that influence the performance of each dehumidification method are identified. The performance of condensing dehumidification is affected mostly by the humidity ratio of indoor air, whereas the outdoor air temperature has a minor impact. The humidity ratio difference between indoor and outdoor air is the most influential factor in the desiccant wheel dehumidification, followed by the outdoor air temperature. Under the operating conditions examined in the present study, the condensing dehumidification shows 3–4 times higher exergy efficiency than the desiccant wheel dehumidification. Therefore, the condensing dehumidification should be preferred over the desiccant wheel dehumidification for typical indoor dehumidification applications.

  • 23.
    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.

  • 24.
    Gomez-Rueda, Yamid
    et al.
    Dept Mech Engn, Celestijnenlaan 300, B-3001 Leuven, Belgium..
    Zaini, Ilman Nuran
    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.
    Helsen, Lieve
    Dept Mech Engn, Celestijnenlaan 300, B-3001 Leuven, Belgium.;Energyville, Thor Pk, Waterschei, Belgium..
    Thermal tar cracking enhanced by cold plasma - A study of naphthalene as tar surrogate2020In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 208, article id 112540Article in journal (Refereed)
    Abstract [en]

    Gasification has been proposed as a good solution for recovering energy from waste and biomass in the form of syngas. However, the presence of tar limits syngas applications. Tar model molecules have been removed by cold plasmas up to 400 degrees C, but to avoid syngas cooling tar removal above 600 degrees C is required. To investigate tar removal by cold plasma at higher temperatures, two sets of experiments were done, one to identify tar composition from MSW gasification, and a second one to crack in a nanosecond-pulsed corona plasma at high temperatures the most refractory tar compound found, naphthalene. In this paper, we report the first results of cold plasma for tar cracking at temperatures up to 1100 degrees C, revealing that this tandem can remove naphthalene completely at 800 degrees C, compared to the 1000 degrees C needed in case of thermal cracking alone. The synergy between plasma and thermal cracking is driven by higher energy densities when temperatures increase. However, this synergy stops when thermal cracking reactions predominate.

  • 25.
    Gough, Matthew
    et al.
    Univ Porto, Fac Engn, INESC TEC, Porto, Portugal..
    Rakhsia, Kush
    KTH.
    Bandeira, Tiago
    KLUGIT Energy, Aveiro, Portugal..
    Amaro, Hugo
    Inst Pedro Nunes, Coimbra, Portugal..
    Castro, Rui
    Univ Lisbon, INESC ID, Inst Super Tecn, Lisbon, Portugal..
    Catala, Joao P. S.
    Univ Porto, Fac Engn, SYSTEC ARISE, Porto, Portugal..
    Design and implementation of a data-driven intelligent water heating system for an island community: A case study2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 285, article id 117007Article in journal (Refereed)
    Abstract [en]

    Water heating accounts for approximately 25% of household energy use in developed countries. Therefore, the optimal control of water heating through the deployment of intelligent residential Electric Water Heaters (EWH) brings significant benefits. This paper presents an innovative design and implementation of an easy-to-use device for intelligent residential water heating. The device relied upon machine learning techniques to forecast a consumer's hot water demand and optimize the operation of an EWH using a novel data collection process that relied on non-intrusive vibration data alone. The device was deployed in a six-month pilot project on the island of Sa similar to o Miguel, Portugal. The major difficulties were the novel use of vibration data to forecast the volume of hot water used and the uncertain behavior of the consumers. The challenges of only using vibration data were solved by careful data collection and artificial intelligence methods. To tackle the issue of uncertain consumer behavior, an innovative 'heat now' function was incorporated into the device to override the novel control framework. Results show that the device could accurately forecast hot water demand and optimally operate the EWH to meet this demand. The results showed an average reduction of 1.33 kWh/day per consumer, which equates to an average decrease of 35.5% in water heating costs. Calculations show that these devices can reduce the total energy used by 2832 kWh daily or 0.21% of total electricity generated. Furthermore, a fleet of these devices could reduce thermal generation by 0.37%, reducing emissions by 693.31 tons of CO2 per year. The results from the consumer survey show that the device did not affect the consumer's comfort, validating the benefits and efficacy of the proposed device. Hence, the paper shows that a simple-to-use, novel device using an innovative forecasting algorithm based on non-intrusive vibration data brings numerous quantifiable benefits to actual consumers and electrical utilities.

  • 26.
    Groppi, Daniele
    et al.
    Univ Tuscia, Dept Econ Engn Soc & Business Org DEIM, Via Paradiso 47, I-01100 Viterbo, Italy..
    Kumar, Shravan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Gardumi, Francesco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Garcia, Davide Astiaso
    Sapienza Univ Rome, Dept Planning Design & Technol Architecture, Rome, Italy..
    Optimal planning of energy and water systems of a small island with a hourly OSeMOSYS model2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 276, p. 116541-, article id 116541Article in journal (Refereed)
    Abstract [en]

    Islands all over the world face common challenges connected to energy costs and greenhouse gas emissions. Thus, islands have been identified as perfect sites for implementing and testing innovative solutions to boost the green energy transition towards a sustainable and clean energy system. The supply of clean water is a major issue that affects small islands, and desalination, particularly Reverse Osmosis, represents a valid solution to this challenge. In this research, an energy system model is used to analyse long-term water and energy supply strategies of the tourist island of Favignana, Italy. The model is built with the Open Source long-term energy modelling tool OSeMOSYS at an hourly resolution. It considers both the potential synergies offered by Reverse Osmosis Desalination and the use of water storage to store the excess electricity when needed. The indirect emissions for the maritime transportation of goods and fuels (i.e., water and diesel) to the island are also accounted for. Different energy policies are compared to understand how a carbon tax, a limit on emissions and no policy would impact the long-term energy strategy of the island. The results show that a carbon tax that covers also the maritime transportation sector would lead to the lowest overall cumulative emissions. They additionally reveal that the contribution of emissions for maritime transportation of goods and fuels is relevant and cannot be neglected if a full decarbonisation has to be achieved. On the technological side, investment in a desalination plant is the most viable option in all cases. Finally, for the first time, OSeMOSYS is applied with hourly resolution and the results are compared with those obtained with lower time resolution showing that inaccuracies are found both for overall values and for the dispatching strategies.

  • 27.
    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.

  • 28. Guo, S.
    et al.
    Liu, Q.
    Zhao, J.
    Jin, G.
    Wu, W.
    Yan, Jinyue
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. School of Business, Society and Engineering, Mälardalen University, 721 23 Västerås, Sweden.
    Li, H.
    Jin, H.
    Mobilized thermal energy storage: Materials, containers and economic evaluation2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 177, p. 315-329Article in journal (Refereed)
    Abstract [en]

    The transportation of thermal energy is essential for users who are located far away from heat sources. The networks connecting them achieve the goal in efficient heat delivery and reasonable cost, especially for the users with large heat demands. However, it is difficult to satisfy the heat supply of the detached or emergent users with the existing pipelines. Therefore, a promising alternative, called mobilized thermal energy storage (M-TES), was proposed to deliver the heat flexibly without the restriction of networks. In this paper, a review of studies on M-TES is conducted in terms of materials, containers and economic evaluation. The potential candidates of materials, such as sugar alcohols, hydrated salts, alkalies and zeolite are reviewed and compared based on their thermophysical properties, price, advantages and disadvantages. Various containers, including the shell-and-tube, encapsulated, direct-contact, detachable and sorptive types, are discussed from the aspects of configuration, performance and utilization. Furthermore, the studies on the economic evaluation of M-TES systems are summarized and discussed based on the analysis of the economic indicators, including initial cost, operating cost, revenue, subsidy and energy cost. Finally, the challenges and future perspectives for developing M-TES are presented.

  • 29.
    Hosseini, Arian
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Goudarzi, Navid
    Univ N Carolina, William States Lee Coll Engn, Charlotte, NC 28223 USA..
    Design and CFD study of a hybrid vertical-axis wind turbine by employing a combined Bach-type and H-Darrieus rotor systems2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 189, p. 49-59Article in journal (Refereed)
    Abstract [en]

    The objective of this work was to design, simulate and evaluate the performance of an innovative hybrid vertical axis wind turbine (VAWT) for obtaining an extended operational range and enhancing self-starting capabilities. An extensive research was conducted to explore the design parameters for obtaining an optimum novel hybrid VAWT configuration. The hybrid VAWT consisting of a 2-bladed modified Savonius Bach-type rotor and a 3-bladed Darrieus turbine was modeled and analyzed in computational fluid dynamics (CFD) to calculate the characteristic parameters of the rotor system. The geometry was then used to generate the grid in ANSYS Meshing for computational fluid dynamics (CFD) analyses to evaluate the performance of the designed hybrid VAWT. Results indicated that while the Darrieus turbine had the highest coefficient of power (C-p) of 48.4% at a TSR of 2.50, it suffered from high start-up torque requirements. The hybrid turbine demonstrated self-starting capabilities while reaching a maximum C-p of 41.4% at a TSR of 2.5 and operation up to a TSR value of 4.5. When compared to previous hybrid VAWT designs, the proposed configuration demonstrated improvements to the efficiency and operational range which support the energy sustainability prospects.

  • 30.
    Katla-Milewska, Daria
    et al.
    Silesian University of Technology, Akademicka 2A, Gliwice 44 100, Poland, Department of Power Engineering and Turbomachinery, Silesian University of Technology, Akademicka 2A.
    Nazir, Shareq Mohd
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Skorek-Osikowska, Anna
    Silesian University of Technology, Akademicka 2A, Gliwice 44 100, Poland, Department of Power Engineering and Turbomachinery, Silesian University of Technology, Akademicka 2A.
    Synthetic natural gas (SNG) production with higher carbon recovery from biomass: Techno-economic assessment2024In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 300, article id 117895Article in journal (Refereed)
    Abstract [en]

    Due to the growth in the share of renewable energy sources (RES) in the power generation sector worldwide and their intermittency, storage of surplus electricity is needed. The technology known as Power to X (PtX) facilitates the extended storage of excess electricity by converting it into gaseous or liquid fuels such as hydrogen, methane, ammonia, or methanol. This study examines the potential of synthetic natural gas (SNG) technology as a viable energy storage solution. The paper introduces three distinct SNG production systems, all of which are based on the processes of biomass gasification and methanation. Case 1 assumes further CO2 capture from generated SNG, and Cases 2 and 3 additionally assume hydrogen production and almost complete CO2 utilization by syngas hydrogenation via the methanation process. The methanation process converts syngas and hydrogen into SNG with a high methane content (>90 vol% dry), that can be injected into the natural gas grid. The thermodynamic and economic potential of SNG production systems is presented in this work. The simulations were conducted using the AspenONE software. The methanation process was analyzed for various design conditions such as methanation temperature and pressure, and different H2:CO, and H2:CO2 ratios. The estimated cold gas efficiency of proposed SNG production systems varies from 63.27% to 77.10% and can be increased up to about 69.10–75.58% when the recovery of heat from methanation is considered. A sensitivity analysis was conducted to determine the break-even price of SNG, considering different scenarios for the costs of feedstock, specifically biomass and electricity. The results indicate that under the most optimistic conditions, the break-even price of SNG is estimated to be 115 €/MWhSNG, 58 €/MWhSNG and 67 €/MWhSNG for Cases 1, 2, and 3, respectively.

  • 31. 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)
  • 32.
    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.

  • 33.
    Kumar, Shravan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Thakur, Jagruti
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Cunha, Jose Maria
    INEGI, Inst Sci & Innovat Mech & Ind Engn, Porto, Portugal..
    Gardumi, Francesco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Kok, Ali
    Vienna Univ Technol, Vienna, Austria..
    Lisboa, Andre
    INEGI, Inst Sci & Innovat Mech & Ind Engn, Porto, Portugal..
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Techno-economic optimization of the industrial excess heat recovery for an industrial park with high spatial and temporal resolution2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 287, p. 117109-, article id 117109Article in journal (Refereed)
    Abstract [en]

    With increasing heating and cooling demands, decarbonisation of the heating and cooling sectors is key to achieving a carbon-neutral energy system. Using industrial excess heat in heating systems helps offset emissions by reducing the use of fossil fuels. While several studies have analysed the temperature of heat availability, the cost of extending or constructing the heating network and techno-economic feasibility, it is important to consider all aspects together to achieve a comprehensive design of industrial excess heat recovery. This study proposes a method to link an energy system optimisation tool with a spatial analysis tool and an exergy analysis tool to achieve a comprehensive design. An iterative soft link is implemented between the energy system model and the spatial analysis tool for high spatial and temporal resolution. The developed method is applied to a case study of an industrial park in Greece. Scenarios are developed to assess the robustness of the developed method and the system profitability of excess heat recovery. The scenarios indicated that the profitability of excess heat depends heavily on the price of natural gas with the share of excess heat increasing from 10% to 45% with a 20% increase in natural gas prices in cases where heat pumps are needed for temperature boosting. In cases where heat pumps are not needed, excess heat indicates higher system profitability with a share of around 40% and reduces the emissions by around 50 times. The method provides robust results in considered scenarios with convergence within four iterations.

  • 34.
    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.
    Grönkvist, Stefan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, 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.

  • 35. 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)
  • 36.
    Li, Fangfang
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden.
    Li, Yangshuo
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden.
    Cao, Jian
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Carvalho, Lara
    School of Business, Society & Engineering, Mälardalen University, Västerås 72123, Sweden.
    Lundgren, Joakim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology. Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden; Department of Chemical Engineering and Technology, Chemical Technology, KTH Royal University of Technology, Stockholm 10044, Sweden.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology. Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden; Department of Chemical Engineering and Technology, Chemical Technology, KTH Royal University of Technology, Stockholm 10044, Sweden.
    Zhang, Xiangping
    Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
    Liu, Yanrong
    Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
    Ji, Xiaoyan
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden.
    Combination of CO2 electrochemical reduction and biomass gasification for producing methanol: A techno-economic assessment2024In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 307, article id 118380Article in journal (Refereed)
    Abstract [en]

    Combining CO2 electrochemical reduction (CO2R) and biomass gasification for producing methanol (CH3OH) is a promising option to increase the carbon efficiency, reduce total production cost (TPC), and realize the utilization of byproducts of CO2R system, but its viability has not been studied. In this work, systematic techno-economic assessments for the processes that combined CO2R to produce CO/syngas/CH3OH with biomass gasification were conducted and compared to stand-alone biomass gasification and CO2R processes, to identify the benefits and analyze the commercialization potential of different pathways under current and future conditions. The results demonstrated that the process that combined biomass gasification with CO2R to CO represents a viable pathway with a competitive TPC of 0.39 €/kg-CH3OH under the current condition. For all the combined cases, electricity usage for CO2R accounts for 36–76% of total operating cost, which plays a key role for TPC. Sensitivity analysis confirmed that the process that combined biomass gasification with CO2R to CO is sensitive to the price of electricity, while both CO2R performance and prices of stack and electricity are important for the processes that combined with CO2R to syngas/CH3OH.

  • 37.
    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.

  • 38.
    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.

  • 39.
    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.

  • 40.
    Mateu-Royo, Carlos
    et al.
    Univ Jaume 1, Dept Mech Engn & Construct, ISTENER Res Grp, Campus Riu Sec S-N, E-12071 Castellon de La Plana, Spain..
    Sawalha, Samer
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mota-Babiloni, Adrian
    Univ Jaume 1, Dept Mech Engn & Construct, ISTENER Res Grp, Campus Riu Sec S-N, E-12071 Castellon de La Plana, Spain..
    Navarro-Esbri, Joaquin
    Univ Jaume 1, Dept Mech Engn & Construct, ISTENER Res Grp, Campus Riu Sec S-N, E-12071 Castellon de La Plana, Spain..
    High temperature heat pump integration into district heating network2020In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 210, article id 112719Article in journal (Refereed)
    Abstract [en]

    This study illustrates the potential of high temperature heat pumps (HTHPs) integration into district heating network (DHN) through a twofold approach, using DHN as a heat sink and source. It is used as a heat sink of HTHP that uses waste heat from the supermarket's refrigeration system as a heat source whereas it is used as a heat source to HTHP that provides heat to industrial applications. When the DHN acts as the heat sink, the integrated system provides a coefficient of performance (COP) of the waste heat recovery (WHR) system between 3.2 and 5.4, reducing the operating costs between 50% and 100% with an average price ratio of 2.25 compared with the standard CO2 refrigeration system. If the DHN is the heat source, the integrated system provides a COP from 2.8 to 5.7 for a heat sink of 110 degrees C. The alternative low-GWP refrigerants assessment illustrates that HC-290, HFO-1234ze(E) and HFO-1234yf were considered the ideal candidates to replace the HFC-134a, whereas HCFO-1233zd(E) and HCFO-1224yd(Z) were the most promising low-GWP refrigerants to replace HFC-245fa. Finally, the environmental results showed that the utilisation of the DHN as the heat sink in the integrated system solution produces about 60% lower equivalent CO2 emissions than the DHN generation mix. Moreover, using DHN as the heat source, the equivalent CO2 emissions can be reduced up to 98% in Sweden compared to conventional natural gas boilers. Hence, the combination of HTHPs and the DHN represents a step forward in the mitigation of climate change through the utilisation of sustainable energy conversion technologies.

  • 41.
    Meha, Drilon
    et al.
    Univ Zagreb, Fac Mech Engn & Naval Architecture, Zagreb, Croatia.;Univ Prishtina, Fac Mech Engn, Hasan Prishtina, Pristina, Kosovo..
    Thakur, Jagruti
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Novosel, Tomislav
    North West Croatia Reg Energy Agcy, Zagreb, Croatia..
    Puksec, Tomislav
    Univ Zagreb, Fac Mech Engn & Naval Architecture, Zagreb, Croatia..
    Duic, Neven
    Univ Zagreb, Fac Mech Engn & Naval Architecture, Zagreb, Croatia..
    A novel spatial?temporal space heating and hot water demand method for expansion analysis of district heating systems2021In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 234, article id 113986Article in journal (Refereed)
    Abstract [en]

    The fourth generation of district heating will play a significant role in the decarbonization of energy systems. In general, only space heating demand is considered when assessing the district heating potential, excluding hot water. In contrast, the hot water demand accounts for up to 18% of total final energy demand in buildings. Hence, in this paper, a spatial?temporal method for annual hot water demand is considered in conjunction with space heating demand while technically and economically assessing the expansion potential of the district heating. A bottom-up heat demand mapping process was carried out for Pristina city to identify the space heating demand of buildings, while a top-down approach was used for spatial mapping of hot water demand. Hourly, daily, weekly and seasonal hot water demand profiles, besides heating degree-day method used for space heating, were considered when estimating the temporal operation of district heating. The findings show that the existing district heating can be increased four times when excluding hot water and five times when considering both space heating and hot water demand of buildings. Moreover, the heat supply capacities needed in district heating to cover space heating and hot water demand would be 600 MW and 70 MW respectively.

  • 42.
    Mirmohammadi, Seyed Aliakbar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Behi, Mohammadreza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ghanbarpour, Morteza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Cooling performance study of a novel heat exchanger in an absorption system2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 180, p. 1001-1012Article in journal (Refereed)
    Abstract [en]

    The paper is focusing on a shell and plate heat exchanger of a novel absorption refrigeration system. The system is composed of two vacuum vessels connected together with a steam channel and one heat exchanger is located in each vessel. The first heat exchanger is called reactor where working fluid and salt exist and the second heat exchanger or evaporator/condenser (C/E) is where only water exists. The propylene glycol-based (PG) heat transfer fluid is used on the shell side of both heat exchangers as the media to exchange the heat between boilers and reactor in one vessel and between cold environment and condenser/evaporator in another vessel. An experimental test rig was built to investigate the performance of the evaporator/condenser heat exchanger. Then, a three-dimensional (3D) Computational Fluid Dynamics (CFD) model was developed. The experimental result was then used to validate the numerical model developed by using Ansys/Fluent software. A parametric study has been intended to find a more appropriate design for the heat exchanger in order to increase heat transfer performance. Results of the parametric study demonstrated that the cooling performance is doubled by increasing the diameter of the plate from 0.14 m to 0.2 m. In addition, to obtain the maximum heat transfer performance, Reynolds number and distance between plates should be 9 and 0.5 m, respectively. Two correlations have been developed for the outlet temperature and cooling power of the heat exchanger which are functions of heat transfer coefficient. The results of this study can be of vital importance for improving the cooling power of the system, remarkably.

  • 43.
    Montes, M. J.
    et al.
    E.T.S. Ingenieros Industriales - UNED, C/Juan del Rosal 12, 28040 Madrid, Spain, C/Juan del Rosal 12.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Linares, J. I.
    ICAI School of Engineering, Comillas Pontifical University, Alberto Aguilera, 25, 28015 Madrid, Spain, Alberto Aguilera, 25.
    Reyes-Belmonte, M. A.
    Department of Chemical and Energy Technology, School of Experimental Sciences and Technology (ESCET), Rey Juan Carlos University, 28933 Móstoles, Madrid, Spain, 28933 Móstoles.
    Advances in solar thermal power plants based on pressurised central receivers and supercritical power cycles2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 293, article id 117454Article in journal (Refereed)
    Abstract [en]

    This work addresses the comparative thermo-economic study of different configurations of solar thermal power plants, based on supercritical power cycles and pressurised central receiver systems. For all the cases examined, two innovations are introduced in the solar subsystem, compared to other similar studies. Firstly, the heat transfer fluid in the receiver is either a pressurised gas or a supercritical fluid. Secondly, the receiver is composed of compact structures performing as absorber panels, arranged in a radial configuration. The investigation considers different supercritical CO2 recompression cycles of 50 MWe, including a novel proposal of a directly coupled cycle with heat input downstream of the turbine. Furthermore, the study evaluates different heat transfer fluids in the receiver, specifically CO2, N2, and He, concluding that the former is preferred due to its better thermal performance. The main results show that an increase in the receiver inlet pressure yields to a reduction in its size, favouring the thermal efficiency but penalising the optical efficiency of the solar field. Therefore, optimal working pressures may exist for each configuration, depending on the operating temperature. When comparing the optimal configurations, it is observed that the plant based on the intercooling cycle demonstrates the highest overall efficiency, reaching 32.05%. At last, an economic analysis is conducted to assess the viability of the identified optimal configurations. In this regard, the plant based on the partial-cooling cycle exhibits the lowest levelised cost of electricity at 0.15 $/kWh. This is primarily due to its lower investment cost. The innovative directly coupled cycle follows closely with a cost of 0.17 $/kWh, driven by its high electricity production resulting from its low self-consumption.

  • 44.
    Mosca, Roberto
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Laudato, Marco
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Mihaescu, Mihai
    KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Modeling radial turbine performance under pulsating flow by machine learning method2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227Article in journal (Refereed)
  • 45.
    Mossie, Alebachew T.
    et al.
    AAU Addis Ababa Univ, Sch Elect & Comp Engn, Addis Ababa 3614, Ethiopia..
    Khatiwada, Dilip
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bekele, Getachew
    AAU Addis Ababa Univ, Sch Elect & Comp Engn, Addis Ababa 3614, Ethiopia..
    Investigating energy saving and climate mitigation potentials in cement production: A case study in Ethiopia2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 287, p. 117111-, article id 117111Article in journal (Refereed)
    Abstract [en]

    The cement industry is one of the most energy and emission-intensive sectors, accounting for approximately 7% of total-industrial energy use and 7% of global CO2 emissions. This study investigates the potential energy savings and CO2 abatement in the cement plants of Ethiopia. A Benchmarking and Energy Saving Tool for Cement is used to compare the energy use performance of the individual cement plants to best practices. The study reveals that all the surveyed plants are less efficient, with an average energy saving potential of 36% indicating a significant potential for energy efficiency improvement. Then, twenty-eight energy efficiency measures are identified and analyzed using a bottom-up energy conservation supply curve model. The results show that the cost-effective electrical energy and fuel-saving potentials of these measures are estimated to be 99 Gigawatt hours per year which is about 11.5% of the plants' annual electrical energy consumption and, 2.7 Petajoules per year which is to be 12.5% of the plants' annual fuel consumption, respectively. The cost-effective fuel measures have an annual average CO2 emission reduction potential of 254 kilo-tonnes per year which covers about 5% of the total CO2 emission. Sensitivity analysis is conducted using the key parameters that show some discrepancy in the base case results. This study could be used as a reference for policymakers to understand the potential for energy savings and CO2 abatement. It could also be used to design policies in improving energy efficiency in the cement sector.

  • 46. 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%.

  • 47.
    Neshat, Mehdi
    et al.
    Univ Adelaide, Sch Comp Sci, Optimisat & Logist Grp, Adelaide, SA, Australia..
    Nezhad, Meysam Majidi
    Sapienza Univ Rome, Dept Astronaut Elect & Energy Engn DIAEE, Rome, Italy..
    Abbasnejad, Ehsan
    Univ Adelaide, Australian Inst Machine Learning, Adelaide, SA, Australia..
    Mirjalili, Seyedali
    Torrens Univ Australia, Ctr Artificial Intelligence Res & Optimizat, Brisbane, Qld 4006, Australia.;Yonsei Univ, Yonsei Frontier Lab, Seoul, South Korea..
    Bertling, Lina
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering. KTH Royal Inst Technol Stockholm, Sch Elect Engn & Comp Sci, Stockholm, Sweden..
    Garcia, Davide Astiaso
    Sapienza Univ Rome, Dept Planning Design Technol Architecture, Rome, Italy..
    Alexander, Bradley
    Univ Adelaide, Sch Comp Sci, Optimisat & Logist Grp, Adelaide, SA, Australia..
    Wagner, Markus
    Univ Adelaide, Sch Comp Sci, Optimisat & Logist Grp, Adelaide, SA, Australia..
    A deep learning-based evolutionary model for short-term wind speed forecasting: A case study of the Lillgrund offshore wind farm2021In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 236, article id 114002Article in journal (Refereed)
    Abstract [en]

    Due to expanding global environmental issues and growing energy demand, wind power technologies have been studied extensively. Accurate and robust short-term wind speed forecasting is crucial for large-scale integration of wind power generation into the power grid. However, the seasonal and stochastic characteristics of wind speed make forecasting a challenging task. This study adopts a novel hybrid deep learning-based evolutionary approach in an attempt to improve the accuracy of wind speed prediction. This hybrid model consists of a bidirectional long short-term memory neural network, an effective hierarchical evolutionary decomposition technique and an improved generalised normal distribution optimisation algorithm for hyper-parameter tuning. The proposed hybrid approach was trained and tested on data gathered from an offshore wind turbine installed in a Swedish wind farm located in the Baltic Sea with two forecasting horizons: ten-minutes ahead and one-hour ahead. The experimental results indicated that the new approach is superior to six other applied machine learning models and a further seven hybrid models, as measured by seven performance criteria.

  • 48.
    Novalin, Timon
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Eriksson, Björn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Proch, Sebastian
    Strateg Res, Sandv Mat Technol, SE-81181 Sandviken, Sweden..
    Bexell, Ulf
    Strateg Res, Sandv Mat Technol, SE-81181 Sandviken, Sweden..
    Moffatt, Claire
    Strateg Res, Sandv Mat Technol, SE-81181 Sandviken, Sweden..
    Westlinder, Jorgen
    Strateg Res, Sandv Mat Technol, SE-81181 Sandviken, Sweden..
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Wreland Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Concepts for preventing metal dissolution from stainless-steel bipolar plates in PEM fuel cells2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 253, article id 115153Article in journal (Refereed)
    Abstract [en]

    The bipolar plate (BPP) is a component with vast cost-reduction potential in proton exchange membrane fuel cells (PEMFCs). Apart from mechanical and heat transfer requirements, the most desired BPP properties are high corrosion and low electrical contact resistance. In this study we confirm that due to ionic decoupling between BPPs and electrodes, the surface potentials of the BPPs remain stable even at varying operation loads. These mild potentials, in combination with low metal-ion leeching due to passive-transpassive-passive dissolution in stainless steels, suggest that low-cost carbon-coated stainless steel can readily be used as a BPP in PEMFCs. To prove this, single-fuel cell tests were carried out under realistic driving conditions, including electrochemical analysis, in-situ contact-resistance measurements, and post-mortem investigation of the membrane electrode assembly (MEA) by inductively coupled plasma trace-metal analysis, combined with electron microscopy and Auger spectroscopy of the BPPs. The results show that due to the ionic decoupling, conditions at the BPP surfaces are much less corrosive than previously thought. Furthermore, carbon-coated stainless-steel BPPs prove to be unaffected by global hydrogen starvation, which causes severe MEA degradation independent of the presence or absence of BPPs.

  • 49.
    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.

  • 50.
    Ortis, Astrid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems. Munters AB, Borgarfjordsgatan 16, SE-16440 Stockholm, Sweden..
    Khatiwada, Dilip
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    A comparative life cycle assessment of two desiccant wheel dehumidifiers for industrial applications2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 286, article id 117058Article in journal (Refereed)
    Abstract [en]

    Desiccant wheel dehumidification technology is essential within industrial applications to maintain indoor hu-midity levels and provide low dew points. While the need for desiccant wheel dehumidification has increased in several industrial sectors, it is still an energy-intensive method undergoing rapid technological development. The lack of comprehensive life cycle assessment studies and recently introduced taxonomy by the European Union (EU) prompt the urgency of evaluating the environmental impacts of dehumidification systems. This study performs a comparative life cycle assessment for two desiccant wheel dehumidifiers for industrial applications. We identify the key influencing factors of selected environmental impact categories, e.g., climate change, ozone depletion, and fine particulate matter formation. The study reveals that the usage phase contributes the most, varying between 65% and 99% of the overall impact in all categories, with electricity consumption as the key driver. The cradle-to-gate stage, which shows the second biggest impact (up to 26%), has its most significant share in fine particulate matter formation. The end-of-life (disposal) contributions are insignificant, with an average impact of less than 1%. The scaling factor, operational hours of the systems, the target supply humidity, and the climatic data are the critical parameters for environmental performance. Potential for improvement is seen for an increased recycled content during the cradle-to-gate stage to reduce the impact from raw material inputs and the integration of sustainable energy technology as well as the connection of the systems to energy -efficient equipment during the operational phase. The study could serve as an example on how the EU Taxonomy can be applied for investigating the environmental sustainability of dehumidification systems.

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