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  • 1.
    Abas, N.
    et al.
    University of Gujrat, Hafiz Hayat Campus, Gujrat, Pakistan.
    Kalair, A. R.
    COMSATS University Islamabad, Islamabad, Pakistan.
    Seyedmahmoudian, M.
    Swinburne University, Australia.
    Naqvi, M.
    Karlstad University.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Khan, N.
    COMSATS University Islamabad, Islamabad, Pakistan.
    Dynamic simulation of solar water heating system using supercritical CO2 as mediating fluid under sub-zero temperature conditions2019Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 161, artikkel-id 114152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    CO2 is becoming increasingly important as a mediating fluid, and simulation studies are indispensable for corresponding developments. In this study, a simulation-based performance investigation of a solar water heating system using CO2 as a mediating fluid under sub-zero temperature condition is performed using the TRNSYS® software. The maximum performance is achieved at a solar savings fraction of 0.83 during July. The as lowest solar savingss fraction of 0.41 is obtained during December. The annual heat production of the proposed system under Fargo climate is estimated to be about 2545 kWh. An evacuated glass tube solar collector is designed, fabricated and tested for various climate conditions. Moreover, a detailed comparison of the system's performance at sub/supercritical and supercritical pressures shows that the annual heat transfer efficiency of the modeled system is 10% higher at supercritical pressure than at sub/supercritical pressures. This result can be attributd to the strong convection flow of CO2 caused by density inhomogeneities, especially in the near critical region. This condition resuls in high heat transfer rates.

  • 2.
    Ahmed, Mobyen Uddin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Aslanidou, Ioanna
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Begum, Shahina
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Hatvani, Leo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Olsson, Anders
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Sjödin, Carina
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Skvaril, Jan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zaccaria, Valentina
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dilemmas in designing e-learning experiences for professionals2021Inngår i: Proceedings of the European Conference on e-Learning, ECEL, 2021, s. 10-17Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aims of this research are to enhance industry-university collaboration and to design learning experiences connecting the research front to practitioners. We present an empirical study with a qualitative approach involving teachers who gathered data from newly developed advanced level courses in artificial intelligence, energy, environmental, and systems engineering. The study is part of FutureE, an academic development project over 3 years involving 12 courses. The project, as well as this study, is part of a cross-disciplinary collaboration effort. Empirical data comes from course evaluations, course analysis, teacher workshops, and semi-structured interviews with selected students, who are also professionals. This paper will discuss course design and course implementation by presenting dilemmas and paradoxes. Flexibility is key for the completion of studies while working. Academia needs to develop new ways to offer flexible education for students from a professional context, but still fulfil high quality standards and regulations as an academic institution. Student-to-student interactions are often suggested as necessary for qualified learning, and students support this idea but will often not commit to it during courses. Other dilemmas are micro-sized learning versus vast knowledge, flexibility versus deadlines as motivating factors, and feedback hunger versus hesitation to share work. Furthermore, we present the challenges of providing equivalent online experience to practical in-person labs. On a structural level, dilemmas appear in the communication between university management and teachers. These dilemmas are often the result of a culture designed for traditional campus education. We suggest a user-oriented approach to solve these dilemmas, which involves changes in teacher roles, culture, and processes. The findings will be relevant for teachers designing and running courses aiming to attract professionals. They will also be relevant for university management, building a strategy for lifelong e-learning based on co-creation with industry.

  • 3.
    Akbari, Keramatollah
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Simulation of Indoor Radon and Energy Recovery Ventilation Systems in Residential Buildings2015Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This study aims to investigate the effects of ventilation rate, indoor air temperature, humidity and using a heat recovery ventilation system on indoor radon concentration and distribution.

    Methods employed include energy dynamic and computational fluid dynamics simulation, experimental measurement and analytical investigations. Experimental investigations primarily utilize a continuous radon meter and a detached house equipped with a recovery heat exchanger unit.

    The results of the dynamic simulation show that the heat recovery unit is cost-effective for the cold Swedish climate and an energy saving of about 30 kWh per  floor area per year is possible, while it can be also used to lower radon level.

    The numerical results showed that ventilation rate and ventilation location have significant impacts on both radon content and distribution, whereas indoor air temperature only has a small effect on radon level and distribution and humidity has no impact on radon level but has a small impact on its distribution.

    Fulltekst (pdf)
    fulltext
  • 4.
    Akter, Salina
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Islam, M. Sirajul
    Örebro Univ, Sch Business, Örebro.
    Factors influencing the attitude of women towards purchasing green products: An explorative case study of organic cosmetics in sweden2020Inngår i: JOURNAL OF CONSUMER SCIENCES, ISSN 0378-5254, Vol. 48, s. 38-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates green consumer behavior by analyzing women's attitudes towards purchasing organic cosmetics in Sweden in order to determine the factors that influence their purchasing behavior. The study is based on the modified Theory of Planned Behavior (TPB) explained with primary data collected through an online survey of 220 women who live in Sweden. The findings are in line with the previous studies, which confirm that consumers' attitudes towards green products have a positive influence on purchase intention. Moreover, this study has found that the individual's education and income level have a positive relationship with attitude and future purchase intention.

  • 5.
    Al-Habaibeh, Amin H
    et al.
    Product Innovation Centre, School of Architecture, Design and the Built Environment, Nottingham Trent University, U.K..
    Hawas, Allan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    An educational and research apparatus for simulating thermal performance and energy efficiency of buildings2021Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Apparatus intended as a teaching aid for studying the thermal efficiency of buildings comprising a scale model of a building or buildings with sensors that monitor the internal and external environments of the model building. The model's temperature may be monitored by way of infrared thermography. Insulating layers can be added and removed to walls, roofs, windows and doors in a modular, interchangeable manner. The thermal environment can be controlled by way of heating or air-conditioning systems and wind circulation and solar radiation can be simulated. The heating and cooling can be computer controlled. The model may be housed in a chamber that may have a removable cover or a handle for transportation.

    Fulltekst (pdf)
    fulltext
  • 6.
    Al-Habaibeh, Amin
    et al.
    Nottingham Trent University, Nottingham, UK.
    Hawas, Allan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Nottingham Trent University, Nottingham, UK.
    Hamadeh, Lama
    Nottingham Trent University, Nottingham, UK.
    Medjdoub, Benachir
    Nottingham Trent University, Nottingham, UK.
    Marsh, Julian
    Sheffield Hallam University, Sheffield, UK.
    Sen, Arijit
    Sheffield Hallam University, Sheffield, UK.
    Enhancing the sustainability and energy conservation in heritage buildings:: The case of Nottingham Playhouse2022Inngår i: Frontiers of Architectural Research, ISSN 2095-2635, E-ISSN 2095-2643, Vol. 11, nr 1, s. 142-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, there is a growing interest in developing energy efficient buildings since it is estimated that buildings account for about 40% of the total primary energy consumption in the world. In relation to existing buildings, energy efficiency retrofits have become an important opportunity to upgrade the energy performance of commercial, public and residential buildings that may reduce the energy consumption, demand and cost. In this paper we cover the energy efficiency deep retrofit process that has been carried out for Nottingham Playhouse theatre building for the aim of enhancing its environmental performance and analysing the energy efficiency gained after implementing certain proposed modifications. It is a nationally protected historic building, listed as Grade II∗ on The National Heritage List for England (NHLE). The building has had insulation enhancement, doors modifications, solar energy installations, energy-saving lights, in addition to improved heating and air conditioning system. The paper presents a novel methodology; and its results indicate significant improvements in the building's energy performance which is demonstrated using infrared thermographic images and data logger sensors where significant energy savings to the building's thermal performance are obtained. The energy saving measures have been completed while maintaining the heritage building's general appearance and architectural features, which have received a Commendation Certificate from The Nottingham Civic Society for this achievement.

  • 7.
    Alinejad, T.
    et al.
    School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
    Yaghoubi, M.
    School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
    Vadiee, Amir
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thermo-environomic assessment of an integrated greenhouse with an adjustable solar photovoltaic blind system2020Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 156, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optimum energy consumption and renewable energy utilization reduce environmental impacts and are cost-effective. They are the key aspects of achieving sustainable energy management, such as in the agricultural industry. The contribution of the horticultural section in the global energy demand is approximately 2%, and among its various sections, greenhouses are one of the main systems in modern agriculture that have a great share on energy consumption. In this study, a rose greenhouse is examined and modeled in EnergyPlus as a greenhouse reference (GR). Validation of the developed greenhouse model is carried out with a site experimental measurement. Using the GR as the basic model, 14 various configurations of greenhouses have been assessed by considering a solar photovoltaic blind system (SPBS) in checkerboard arrays 1 m above the greenhouse roof. These modified greenhouses called solar-blind greenhouses (SBGs) have different shading rates and SPBS sizes. To perform a Thermo-environomic assessment, the effects of various parameters, including temperature, relative humidity, natural gas consumption, electricity consumption, and carbon dioxide (CO2) emission reduction, are studied. Results indicate that covering 19.2% of the roof, with no significant change in the illumination level on the plant canopy, will annually reduce natural gas consumption, electricity demand, and CO2 emission by 3.57%, 45.5%, and 30.56 kg/m2, respectively. Moreover, with the SPBS, the annual electricity production is approximated at 42.7 kWh/m2. © 2020 Elsevier Ltd

  • 8.
    An, Lin
    et al.
    E China Univ Sci & Technol, Peoples R China.
    Yu, Xinhai
    E China Univ Sci & Technol, Peoples R China.
    Yang, Jie
    Univ Shanghai Sci & Technol, Shanghai, Peoples R China.
    Tu, Shan-Tung
    E China Univ Sci & Technol, Peoples R China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Inst Technol, Stockholm, Sweden.
    CO2 capture using a superhydrophobic ceramic membrane contactor2015Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 75, s. 2287-2292Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wetting and fouling of membrane contactor result in performance deterioration of membrane gas absorption system for CO2 post-combustion capture of coal-fired power plants. To solve these problems, in this study, a superhydrophobic ceramic (SC) membrane contactor was fabricated by chemically modification using 1H, 1H, 2H, 2H-perfluorooctylethoxysilane (FAS) solution. The membrane contactor fabrication costs for both SC membrane and PP (polypropylene) membrane contactors per unit mass absorbed CO2 were roughly the same. However, by using the SC membrane, the detrimental effects of wetting can be alleviated by periodic drying to ensure a high CO2 removal efficiency (>90%), whereas the drying does not work for the PP membrane. The SC membrane contactor exhibited a better anti-fouling ability than the PP membrane contactor because the superhydrophobic surface featured a self-cleaning function. To ensure continuous CO2 removal with high efficiency, a method that two SC membrane contactors alternatively operate combined with periodic drying was proposed.

  • 9.
    Anbalagan, Anbarasan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    A passage to wastewater nutrient recovery units: Microalgal-Bacterial bioreactors2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent years, the microalgal–bacterial process has been considered to be a very attractive engineering solution for wastewater treatment. However, it has not been widely studied in the context of conventional wastewater treatment design under Swedish conditions. The technology holds several advantages: as a CO2 sink, ability to withstand cold conditions, ability to grow under low light, fast settling without chemical precipitation, and reducing the loss of valuable nutrients (CO2, N2, N2O, PO4). The process also provides the option to be operated either as mainstream (treatment of municipal wastewater) or side stream (treatment of centrate from anaerobic digesters) to reduce the nutrient load of the wastewater. Furthermore, the application is not only limited to wastewater treatment; the biomass can be used to synthesise platform chemicals or biofuels and can be followed by recovery of ammonium and phosphate for use in agriculture.

    In the present study, the feasibility of applying the process in Swedish temperature and light conditions was investigated by implementing microalgae within the activated sludge process. In this context, the supporting operational and performance indicators (hydraulic retention time (HRT), sludge retention time (SRT) and nutrients removal) were evaluated to support naturally occurring consortia in photo-sequencing and continuous bioreactor configuration. Furthermore, CO2 uptake and light spectrum-mediated nutrient removal were investigated to reduce the impact on climate and the technical challenges associated with this type of system.

    The results identified effective retention times of 6 and 4 days (HRT = SRT) under limited lighting to reduce the electrical consumption. From the perspective of nitrogen removal, the process demands effective CO2 input either in the mainstream or side stream treatment. The incorporation of a vertical absorption column demonstrated effective CO2 mass transfer to support efficient nitrogen and phosphorus removal as a side stream treatment. However, the investigation of a continuous single-stage process as the mainstream showed a requirement for a lower SRT in comparison to semi-continuous operation due to faster settlability, regardless of inorganic carbon. Furthermore, the process showed an effective reduction of influent phosphorus and organic compounds (i.e. COD/TOC) load in the wastewater as a result of photosynthetic aeration. Most importantly, the operation was stable at the temperature equivalent of wastewater (12 and 13 ˚C), under different lighting (white, and red-blue wavelengths) and retention times (6 and 1.5 d HRT) with complete nitrification. Additionally, the biomass production was stable with faster settling properties without any physiochemical separation.

    The outcomes of this thesis on microalgal–bacterial nutrient removal demonstrates that (1) photosynthesis-based aeration at existing wastewater conditions under photo-sequential and continuous photobioreactor setup, (2) flocs with rapid settling characteristics at all studied retention times, (3) the possibility of increasing carbon supplementation to achieve higher carbon to nitrogen balance in the photobioreactor, and (4) most importantly, nitrification-based microalgal biomass uptake occurred at all spectral distributions, lower photosynthetic active radiation and existing wastewater conditions.

    Fulltekst (pdf)
    fulltext
  • 10.
    Anbalagan, Anbarasan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Indigenous microalgae-activated sludge cultivation system for wastewater treatment2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The municipal wastewater is mainly composed of water containing anthropogenic wastes that are rich in nutrients such as carbon, nitrogen and phosphorous. The cost for biological treatment of wastewater is increasing globally due to the population growth in urban cities. In general, the activated sludge (AS) process is a biological nutrient removal process used in wastewater treatment plants (WWTPs). The AS is composed of different microorganisms in which bacteria play a crucial role in wastewater treatment (WWT). During the process, air is bubbled to supply oxygen and methanol is added to improve nitrogen removal, which is released as a gas. Phosphorous is removed in the expense of precipitation chemicals. Altogether, the current process requires electrical energy, precipitation chemicals, handling of excess sludge and it emits carbon dioxide (CO2) as a by-product. This process is still in practise in the WWTPs since 1914 although numerous modifications are implemented to meet the stringent regulations in the European Union and globally.

    Microalgae are microorganisms that perform photosynthesis like plants. They are green and reproduce fast using available nutrients (nitrogen and phosphorous) and CO2 from their environment in the presence of light. As a result of photosynthesis, oxygen is released as waste gas. The synthesised oxygen during this process can be implemented to support the AS bacteria that leads to the microalgae activated sludge (MAAS) process. The main advantage is combined removal of nutrients.

    The vision of the research is to implement the indigenous microalgae cultivation in activated sludge process to consume CO2 and recover the nutrients from wastewater. This study is performed to improve the understanding of the process such as: light utilisation, nutrient removal and recovery of the biomass from wastewater in closed photo-bioreactors. Photo-bioreactors are vessels where the cultivation is carried out in the presence of light. At first, the influence of the light spectrum on micro-algal cultivation is investigated for photosynthetic growth. This is followed by operational challenges of the microalgae cultivation during the AS process. The process is experimentally performed in the photo-bioreactors with different treatment time of the raw wastewater. The results showed that 2 - 6 days of treatment time can be used for reducing nutrients in wastewater if the process is optimised further. Also, nutrient ratio is analysed for the availability of the micro-algal growth. Furthermore, the biogas potential of MAAS showed a biogas yield of about 60-80% within 5 to 9 days.

    At last, the experimental verification of chemically precipitated wastewater showed limitation of phosphorous for micro-algal growth. Additionally, the optimal oxygen supply through light response is verified for photo-bioreactors. The outcome of this study shows that knowing the right conditions can lower the treatment time. By doing so, a stable nutrient removal and reduction of precipitation chemicals can be established as well as a better recovery of valuable nutrients as phosphorous and nitrogen.

    Fulltekst (pdf)
    fulltext
  • 11.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jeanette Castro, Cynthia
    University of Massachusetts Amherst, US.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB Corporate Research, Sweden.
    Nehrenheim, Emma
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Northvolt AB, Sweden.
    Butler, Caitlyn
    University of Massachusetts Amherst, US.
    Influence of environmental stress on the microalgal-bacterial process during nitrogen removalManuskript (preprint) (Annet vitenskapelig)
  • 12.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Influence of light intensity and phosphorous on microalgae activated sludge in phosphate precipitated conditionManuskript (preprint) (Annet vitenskapelig)
  • 13.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Influence of hydraulic retention time on indigenous microalgae and activated sludge process2016Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 91, s. 277-284Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Integration of the microalgae and activated sludge (MAAS) process in municipal wastewater treatment and biogas production from recovered MAAS was investigated by studying the hydraulic retention time (HRT) of semi-continuous photo-bioreactors. An average total nitrogen (TN) removal efficiency (RE) of maximum 81.5 ± 5.1 and 64.6 ± 16.2% was achieved at 6 and 4 days HRT. RE of total phosphorous (TP) increased slightly at 6 days (80 ± 12%) HRT and stabilized at 4 days (56 ± 5%) and 2 days (55.5 ± 5.5%) HRT due to the fluctuations in COD and N/P mass ratio of the periodic wastewater. COD and organic carbon were removed efficiently and a rapidly settleable MAAS with a sludge volume index (SVI_10) of less than 117 mL g-1 was observed at all HRTs. The anaerobic digestion of the untreated MAAS showed a higher biogas yield of 349 ± 10 mL g VS-1 with 2 days HRT due to a low solids retention time (SRT). Thermal pretreatment of the MAAS (120 °C, 120 min) did not show any improvement with biogas production at 6 days (269 ± 3 (untreated) and 266 ± 16 (treated) mL gVS-1), 4 days (258 ± 11(untreated) and 263 ± 10 (treated) mL gVS-1) and 2 days (308 ± 19 mL (treated) gVS-1) HRT. Hence, the biogas potential tests showed that the untreated MAAS was a feasible substrate for biogas production. Results from this proof of concept support the application of MAAS in wastewater treatment for Swedish conditions to reduce aeration, precipitation chemicals and CO2 emissions. 

  • 14.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Continuous microalgae-activated sludge flocs for remediation of municipal wastewater under low temperature2017Inngår i: / [ed] Peter Van der Steen, 2017, s. 1-8Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The operational performance of indigenous microalgae-activated sludge was evaluated regarding the nutrient removal efficiency using raw wastewater collected from Västerås wastewater treatment plant, Sweden at limited artificial surface lighting (290 μmol m-1 sec-1) and Nordic wastewater conditions (13°C). Additionally, the oxygen production and consumption, biomass concentration and its settling was evaluated during the symbiotic algal-bacterial interaction. The results confirmed oxygenic organic compound removal (COD removal of 65-94%) at higher (31-45 d) and lower (13-18 d) sludge retention time (SRT). Also, a complete removal of ammonium throughout the process and partial nitrite-nitrate removal at all SRTs (total nitrogen removal of 41- 62%) were observed. Likewise, a partial phosphorus (P)removal was observed in the effluent which provides an opportunity to capture free P fromthe effluent for recovery as fertiliser. Further, the microalgal growth was slower due to lightor inorganic carbon limitation or ammonium repression caused by higher internal recirculationas observed from ammonium and nitrite-nitrate levels in the PBR. Most importantly, effectivePBR biomass concentration based nutrient removal and relative sludge recirculation have tobe considered in the PBR design to avoid light limitation and activate symbiosis.

  • 15.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Influence of iron precipitated condition and light intensity on microalgae activated sludge based wastewater remediation2017Inngår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, s. 1523-1530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The indigenous microalgae-activated sludge (MAAS) process during remediation of municipal wastewater was investigated by studying the influence of iron flocculation step and light intensity. In addition, availability of total phosphorous (P) and photosynthetic activity was examined in fed-batch and batch mode under northern climatic conditions and limited lighting. This was followed by a semi-continuous operation with 4 d of hydraulic retention time and mean cell residence time of 6.75 d in a photo-bioreactor (PBR) with varying P availability. The fed-batch condition showed that P concentrations of 3–4 mg L−1 were effective for photosynthetic chl. a development in iron flocculated conditions. In the PBR, the oxygen evolution rate increased with increase in the concentration of MAAS (from 258 to 573 mg TSS L−1) at higher surface photosynthetic active radiation (250 and 500 μmol m−2 s−1). Additionally, the rate approached a saturation phase at low MAAS (110 mg L−1) with higher light intensities. Semi-continuous operation with luxury P uptake and effective P condition showed stable average total nitrogen removal of 88 and 92% respectively, with residual concentrations of 3.77 and 2.21 mg L−1. The corresponding average P removal was 68 and 59% with residual concentrations of 2.32 and 1.75 mg L−1. The semi-continuous operation produced a rapidly settleable MAAS under iron flocculated condition with a settling velocity of 92–106 m h−1 and sludge volume index of 31–43 ml g−1 in the studied cases.

  • 16.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Influence of light emitting diodes on indigenous microalgae cultivation in municipal wastewater2015Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 75, s. 786-792Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, the effect of light emitting diodes (LEDs) on microalgae cultivation in municipal wastewater was examined in comparison to the fluorescent light. Two kinds of wastewater were evaluated: first one with low concentration of total phosphorous (TP) and second one with high TP concentration. The nutrient removal and biomass production using LEDs is efficient at photo-synthetically active radiation (PAR) intensity of 107-112 mu mol m(-2) s(-1) which is slightly higher than fluorescent light. Furthermore, this study demonstrates the applicability and distribution of light in wastewater where the environment is not defined. More importantly, winter and rainy periods contribute to dark condition and dilution of wastewater, intense LED light offers a feasible option for the functioning of closed micro algae based activated sludge (MAAS) process for recovery and reuse of nutrients. 

  • 17.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Toledo-Cervantes, A.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Posadas, E.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Rojo, E. M.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Lebrero, R.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    González-Sánchez, A.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Muñoz, R.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Continuous photosynthetic abatement of CO2 and volatile organic compounds from exhaust gas coupled to wastewater treatment: Evaluation of tubular algal-bacterial photobioreactor2017Inngår i: Journal of CO2 Utilization, ISSN 2212-9820, E-ISSN 2212-9839, Vol. 21, s. 353-359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The continuous abatement of CO2 and toluene from the exhaust gas by an indigenous microalgal-bacterial consortium was investigated in a pilot tubular photobioreactor interconnected to an absorption column using diluted centrate in seawater as a free nutrient source. The removal efficiency of CO2 and toluene was maximised in the vertical absorption column by identifying an optimum liquid to gas (L/G) ratio of 15. The photobioreactor supported steady-state nitrogen and phosphorus removals of 91 ± 2% and 95 ± 4% using 15% diluted centrate at 14 and 7 d of hydraulic retention time (HRT), respectively. A decrease in the removal efficiencies of nitrogen (36 ± 5%) and phosphorus (58 ± 10%) was recorded when using 30% diluted centrate at 7 d of HRT. The volumetric biomass productivities obtained at an HRT of 7 d accounted for 42 ± 11 and 80 ± 3 mg TSS L-1 d-1 using 15 and 30% centrate, respectively. Stable CO2 (76 ± 7%) and toluene removals (89 ± 5%) were achieved at an L/G ratio of 15 regardless of the HRT or centrate dilution. Hence, this study demonstrated the potential of algal-bacterial systems for the continuous removal of CO2 and volatile organic compounds from exhaust gas coupled with the simultaneous treatment of centrate. 

  • 18.
    Andersson, Henny
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindmark, Johan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jansson, Joakim
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Suhonen, Anssi
    Savonia University of Applied Sciences.
    Jääskeläinen, Ari
    Savonia University of Applied Sciences.
    Reijonen, Tero
    Savonia University of Applied Sciences.
    Laatikainen, Reino
    University of Eastern Finland.
    Heitto, Anneli
    Finnoflag.
    Hakalehto, Elias
    Finnoflag.
    Technical Output Report – Pilot A in Sweden2014Rapport (Annet vitenskapelig)
  • 19. Andersson, Henny
    et al.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindmark, Johan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jansson, Joakim
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Suhonen, Anssi
    Savonia University of Applied Sciences, University of Eastern Finland, Finland.
    Jääskeläinen, Ari
    Savonia University of Applied Sciences, University of Eastern Finland, Finland.
    Reijonen, Tero
    Laatikainen, Reino
    Heitto, Anneli
    Hakalehto, Elias
    TECHNICAL REPORT ON PILOT A TESTS IN SWEDEN2015Rapport (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 20. Andrén, Lars
    et al.
    Persson, Tomas
    Högskolan Dalarna, Energi och miljöteknik.
    Lennermo, Gunnar
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Handbok för kombinerade sol- och biovärmesystem: Teknik - System - Ekonomi2012Rapport (Annet vitenskapelig)
    Abstract [sv]

    Handboken beskriver olika solfångarkonstruktioner och solvärmekretsens ingående komponenter och ger en grundlig inblick i ackumulatortankens konstruktion och funktion. I boken finns förslag på systemutformning, olika tekniska lösningar och hur systemen bör styras och regleras. Handboken beskriver i första hand utformning-lösning-styrning av kombinationen sol- och pelletsvärme, men tar även upp solvärme i kombination med vedpannor, värmedrivna vitvaror och värmepumpar. Värmesystem med vattenburen värme är utmärkta att kombinera med solvärme, men det är i de flesta fall enklare att få till bra lösningar vid nyinstallation, än vid komplettering av befintlig anläggning. När solvärme och pelletsvärme ska kombineras finns det många alternativ till systemutformning. Det är viktigt att vattenburna pelletssystem utformas korrekt och kombineras på rätt sätt med solvärme för att komforten ska bli hög och elanvändningen låg. Vattenmantlade pelletskaminer med ett vattenburet värmesystem är extra intressant i kombination med solvärme. När eldningen upphör i samband med att värmebehovet avtar kan solvärmen ta över. En generell slutsats är att konventionella svenska pelletspannor med inbyggd varmvattenberedning inte är lämpliga i kombination med solvärmesystem. Den typen av bränslepannor ger komplicerade systemlösningar, höga värmeförluster och det är svårt att åstadkomma en tillräckligt bra temperaturskiktning i ackumulatortanken om varmvattenberedning sker i pannan. Solvärme för varmvattenberedning kan vara ett enkelt och bra komplement till pelletskaminer som genererar varmluft. För solvärmesystem är det viktigt att kraftig temperaturskiktning erhålls när värmelagret laddas ur. Det betyder att ackumulatortankens (eller varmvattenberedarens) nedre vattenvolym ska kylas ner till temperaturer som ligger nära ingående kallvattentemperatur. Ackumulatortankens mellersta del bör kylas till samma temperatur som radiatorreturen. Vid design av solfångarkretsen måste överhettning och stagnation kunna klaras utan risk för glykolnedbrytning eller andra skador på värmebärare eller rörkrets (och andra komponenter i kretsen). Partiell förångning minskar risken för att glykolen skadas då solfångaren når höga stagnationstemperaturer. Solfångarens glykolblandning tillåts koka (förångas) på ett kontrollerat sätt så att endast ånga blir kvar i solfångaren. Vätskevolymen i solfångaren samlas upp i ett större expansionskärl och systemet återfylls när vätskan kondenserar. Dränerande solfångarsystem med enbart vatten är ett möjligt alternativ till konventionella solfångare. De kräver en större noggrannhet vid installationen, så att sönderfrysning undviks. Dränerande systemlösningar är relativt ovanliga i Sverige. Om solfångaren under senhöst-vinter-tidig vår kan arbeta med att förvärma kallvatten från 10 till 20 ºC erhålls en betydligt bättre verkningsgrad på solfångaren (och framför allt ökar värmeutbytet då drifttimmarna ökar väsentligt) än om radiatorreturen (som i bästa fall ligger på temperaturnivån 30 - 40 ºC) ska förvärmas. Därför bör radiatorreturen placeras en bra bit upp från botten i ackumulatortanken och tappvarmvattnet ska förvärmas i en slinga som börjar i tankens botten. Om det finns ett VVC-system måste systemet anslutas på ett speciellt sätt så att ackumulatortankens temperaturskiktning inte störs. En viktig parameter vid ackumulatortankens utformning är att värmeförlusterna hålls låga. Det är viktigt för att klara tappvarmvattenlasten med solvärme under mulna perioder sommartid (men också för att hålla energianvändningen låg). I moderna hus, där ackumulatortanken i regel placeras i bostaden, blir det en komfortfråga att undvika övertemperaturer i det rum där värmelagret placeras. En bra standard på isoleringen (med minimerade värmeförluster) kräver att det finns ett lufttätt skikt över hela isoleringen som dessutom sluter tätt mot röranslutningar. Ofrivillig självcirkulation i anslutande kretsar som kan kyla av och blanda om ackumulatortankens vattenvolym, bör förhindras med backventiler och nedböjning av rören i isolerskiktet eller direkt utanför tanken.

    Fulltekst (pdf)
    FULLTEXT01
  • 21.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Rahman, Moksadur
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zaccaria, Valentina
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Micro Gas Turbines in the Future Smart Energy System: Fleet Monitoring, Diagnostics, and System Level Requirements2021Inngår i: Frontiers in Mechanical Engineering, E-ISSN 2297-3079, Vol. 7, artikkel-id 676853Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The energy generation landscape is changing, pushed by stricter regulations for emissions control and green energy generation. The limitations of renewable energy sources, however, require flexible energy production sources to supplement them. Micro gas turbine based combined heat and power plants, which are used for domestic applications, can fill this gap if they become more reliable. This can be achieved with the use of an engine monitoring and diagnostics system: real-time engine condition monitoring and fault diagnostics results in reduced operating and maintenance costs and increased component and engine life. In order to allow the step change in the connection of small engines to the grid, a fleet monitoring system for micro gas turbines is required. A proposed framework combines a physics-based model and a data-driven model with machine learning capabilities for predicting system behavior, and includes a purpose-developed diagnostic tool for anomaly detection and classification for a multitude of engines. The framework has been implemented on a fleet of micro gas turbines and some of the lessons learned from the demonstration of the concept as well as key takeaways from the general literature are presented in this paper. The extension of fleet monitoring to optimal operation and production planning in relation to the needs of the grid will allow the micro gas turbines to fit in the future green energy system, connect to the grid, and trade in the energy market. The requirements on the system level for the widespread use of micro gas turbines in the energy system are addressed in the paper. A review of the current solutions in fleet monitoring and diagnostics, generally developed for larger engines, is included, with an outlook into a sustainable future.

  • 22.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. University of Oxford, United Kingdom.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Aerothermal Performance of Shielded Vane Design2017Inngår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 139, nr 11, artikkel-id 111003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents an experimental investigation of the concept of using the combustor transition duct wall to shield the nozzle guide vane leading edge. The new vane is tested in a high-speed experimental facility, demonstrating the improved aerodynamic and thermal performance of the shielded vane. The new design is shown to have a lower average total pressure loss than the original vane, and the heat transfer on the vane surface is overall reduced. The peak heat transfer on the vane leading edge–endwall junction is moved further upstream, to a region that can be effectively cooled as shown in previously published numerical studies. Experimental results under engine-representative inlet conditions showed that the better performance of the shielded vane is maintained under a variety of inlet conditions.

  • 23.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Effect of the Combustor Wall on the Aerothermal Field of a Nozzle Guide Vane2018Inngår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 140, nr 5, artikkel-id 051010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In gas turbines with can combustors the trailing edge of the combustor transition duct wall is found upstream of ev- ery second vane. This paper presents an experimental and numerical investigation of the effect of the combustor wall trailing edge on the aerothermal performance of the nozzle guide vane. In the measurements carried out in a high speed experimental facility, the wake of this wall is shown to in- crease the aerodynamic loss of the vane. On the other hand, the wall alters secondary flow structures and has a protective effect on the heat transfer in the leading edge-endwall junc- tion, a critical region for component life. The different clock- ing positions of the vane relative to the combustor wall are tested experimentally and are shown to alter the aerothermal field. The experimental methods and processing techniques adopted in this work are used to highlight the differences be- tween the different cases studied. 

  • 24.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Zaccaria, Valentina
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Fentaye, Amare Desalegn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Development of web-based short courses on control, diagnostics, and instrumentation2020Inngår i: Proceedings of the ASME Turbo Expo 2020, Sep 21-25, 2020, artikkel-id v006t08a004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As a consequence of globalization and advances in digital tools, synchronous or asynchronous distance courses are becoming an integral part of universities’ educational offers. The design of an online course introduces more challenges compared to a traditional on campus course with face to face lectures. This is true especially for engineering subjects where problem or project-based courses may be preferred to stimulate critical thinking and engage the learners with real-life problems. However, realizing this with distance learning implies that a similar study pace should be kept by the learners involved. This may not be easy, since individual pace is often a motivation for choosing a distance course. Student engagement in group projects, collaborations, and the proper design of examination tasks are only some of the challenges in designing a distance course for an engineering program. 

    A series of web-based courses on measurement techniques, control, and diagnostics were developed and delivered to groups of learners. Each course comprised short modules covering key points of the subject and aimed at getting learners to understand both the fundamental concepts that they do not typically learn or understand in the respective base courses and to build on that knowledge to reach a more advanced cognitive level. 

    The experience obtained in the courses on what strategies worked better or worse for the learners is presented in this paper. A comparison between the courses provides an interesting outlook on how the learners reacted to slightly different requirements and incentives in each course. The results from the evaluation of the courses are also used as a base for discussion.

    The background and availability of the learners is closely linked to how a course should be designed to optimally fit the learning group, without compromising on the achievement of the learning outcomes. This series of courses is a good example of continuous professional development courses in the field of control, diagnostics, and instrumentation (CDI), and brings with it a number of challenges and opportunities for the development of online courses. 

  • 25.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zaccaria, Valentina
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Pontika, E.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Zimmerman, Nathan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kalfas, A. I.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Teaching gas turbine technology to undergraduate students in Sweden2018Inngår i: Proceedings of the ASME Turbo Expo, American Society of Mechanical Engineers (ASME) , 2018, Vol. 6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the teaching of gas turbine technology in a third-year undergraduate course in Sweden and the challenges encountered. The improvements noted in the reaction of the students and the achievement of the learning outcomes is discussed. The course, aimed at students with a broad academic education on energy, is focused on gas turbines, covering topics from cycle studies and performance calculations to detailed design of turbomachinery components. It also includes economic aspects during the operation of heat and power generation systems and addresses combined cycles as well as hybrid energy systems with fuel cells. The course structure comprises lectures from academics and industrial experts, study visits, and a comprehensive assignment. With the inclusion of all of these aspects in the course, the students find it rewarding despite the significant challenges encountered. An important contribution to the education of the students is giving them the chance, stimulation, and support to complete an assignment on gas turbine design. Particular attention is given on striking a balance between helping them find the solution to the design problem and encouraging them to think on their own. Feedback received from the students highlighted some of the challenges and has given directions for improvements in the structure of the course, particularly with regards to the course assignment. This year, an application developed for a mobile phone in the Aristotle University of Thessaloniki for the calculation of engine performance will be introduced in the course. The app will have a supporting role during discussions and presentations in the classroom and help the students better understand gas turbine operation. This is also expected to reduce the workload of the students for the assignment and spike their interest.

  • 26.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zaccaria, Valentina
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Rahman, Moksadur
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Oostveen, Mark
    Micro Turbine Technology bv, Eindhoven, Netherlands.
    Olsson, Tomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. RISE SICS, Västerås, Sweden.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Towards an Integrated Approach for Micro Gas Turbine Fleet Monitoring, Control and Diagnostics2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Real-time engine condition monitoring and fault diagnostics results in reduced operating and maintenance costs and increased component and engine life. Prediction of faults can change the maintenance model of a system from a fixed maintenance interval to a condition based maintenance interval, further decreasing the total cost of ownership of a system. Technologies developed for engine health monitoring and advanced diagnostic capabilities are generally developed for larger gas turbines, and generally focus on a single system; no solutions are publicly available for engine fleets. This paper presents a concept for fleet monitoring finely tuned to the specific needs of micro gas turbines. The proposed framework includes a physics-based model and a data-driven model with machine learning capabilities for predicting system behaviour, combined with a diagnostic tool for anomaly detection and classification. The integrated system will develop advanced diagnostics and condition monitoring for gas turbines with a power output under 100 kW.

    Fulltekst (pdf)
    fulltext
  • 27.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Zimmerman, Nathan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Pontika, Evangelia
    Aristotle Univ Thessaloniki, Dept Mech Engn, Thessaloniki, Greece.
    Kalfas, Anestis
    Aristotle Univ Thessaloniki, Dept Mech Engn, Thessaloniki, Greece.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Reforming heat and power technology course structure using student feedback to enhance learning experience2021Inngår i: International Journal of Mechanical Engineering Education, ISSN 0306-4190, E-ISSN 2050-4586, Vol. 49, nr 4, s. 410-434Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main outcomes of an engineering course should be for the students to achieve the educational goals, enhance their problem solving capabilities and develop essential skills for their future career. In that context, it is important to understand what motivates the students and what helps them develop an engineering mindset. This paper discusses the improvement of a course with the use of student feedback to motivate students and help them develop essential skills. The purpose of the paper is to provide insight into how different aspects of the course are linked to the students’ growth. Different activities have been integrated in the course over the past years. The effect these have on the student motivation to follow the course and develop skills, knowledge and interest in the subject is discussed through the analysis of student performance, student feedback and the experience of the lecturers. The improvements in the course based on the student feedback were received positively by the students, whose learning experience improved, even though the workload of the course was high. Their motivation to successfully complete the course has also increased through the changes in the delivery of the course and the support by the teachers. The combination of student feedback and teacher experience is key for the improvement of a course, while ensuring that the students develop their engineering knowledge. Therefore, the teachers should strike a balance between helping the students find the solution and encouraging them to think on their own in order to develop essential skills. 

  • 28.
    Avelin, Anders
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Process Modeling of Combustion and Digesters for On-line Applications2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The use of biomass has increased in recent years due to the efforts to reduce the high emissions of greenhouse gases, primarily carbon dioxide from combustion of fossil fuels. At the same time industrial processes have become more complex because of increased production rates and profitability requirements. A higher degree of automation is needed when the processes are too complex to be handled manually. There is a need to find modeling strategies that can automatically handle the challenges that the conversion of biomass in an industrial process entails, such as operational changes, decreasing component and overall system efficiency, drifting sensors, etc. The objective of this thesis is to develop a methodology for on-line applications in industrial processes. Dynamic process models have been developed for continuous digesters and boilers. Process models have been evaluated for their use in continuous industrial process. Applications that have been studied are monitoring and diagnostics, advanced control and decision support. The process models are designed for on-line simulations. The results shows that the use of mathematical simulation models can improve the use of both process data and process understanding, to achieve improved diagnostics, advanced control and process optimization. In the two examples of industrial processes covered in this thesis, we can see that similar types of models can be used for completely different types of processes, such as pulp digesters and boilers. It also demonstrates the ability to combine soft sensors and hard sensors with physical models to take the information to a higher level of utilization.

    Fulltekst (pdf)
    fulltext
  • 29.
    Avelin, Anders
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Effect of different renovation actions, their investment cost and future potential2017Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 143, s. 73-79Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    65% of the buildings in Västerås, situated in the region of Mälardalen, Sweden were built before 1970. It is thus time for renovation. The situation is the same in most cities in Sweden and Northern Europe. The depth of renovation can be quite different. In this paper we evaluate some examples where cost is compared to energy saving effect. How to plan renovation to make use of the available capital in the cities is discussed. As a complement to direct renovation actions also behavior change with respect to energy is discussed and exemplified. The cost for energy actions in relation to other renovation aspects is discussed especially for the passive house case in Allingsås, Sweden. The passive house center calculate an extra cost for passive house standard to be 10 000 €/apartment while an external consultant has the figure 40 000 € of the total cost of 120 000 €. With this space heating can be 18 kWh/m2.year, or a reduction by 84 % with respect to space heating and 62% for overall heat and hot water demand. If you use the latter cost figure passive house standard is not motivated from an energy savings perspective while if using the lower figure it is very interesting. For the other less deep renovations we see that adding more insulation and three glass windows is motivated if the degradation has been strong, while a simpler renovation may be ok if the outer surface coating is not too bad. For these less deep renovations we see cost figures of 65 €/m2 respectively 28 €/m2 with reduction of heating and hot water demand of 56 % respectively 34 %. 

  • 30.
    Avelin, Anders
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Skvaril, Jan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Aulin, Robert
    Swedish University of Agricultural Sciences, Sweden.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Forest biomass for bioenergy production – comparison of different forest species2014Inngår i: / [ed] J. Yan, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Forest biomass is a renewable and sustainable source of energy that can be used for producing electricity, heat, and biofuels. The production of biomass for energy is considered to be an important step in developing sustainable communities and managing greenhouse gas emissions effectively. Biomass properties vary and are commonly associated with plant species. Hence, efficient methods to predict biofuel characteristics will greatly affect the utilization and management of feedstock production. In this paper attempt was made to correlate various chemical characteristics with NIR spectra. Wood chips from various plant species was analyzed for lignin content, heating value, ash content and NIR and the results were evaluated with correlation, PCA and PCR. Initial evaluation showed promising results where chemical components in the wood correlate to NIR spectra. A selection of results will be presented in this paper. Further analysis as well as results from PCA and PCR models will be presented in the full paper version.

    Fulltekst (pdf)
    fulltext
  • 31.
    Azaza, Maher
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Tunis El Manar University, Tunis, Tunisia.
    Tanougast, C.
    Lorraine University, France.
    Fabrizio, E.
    University of Torino, Grugliasco, Italy.
    Mami, A.
    Tunis El Manar University, Tunis, Tunisia .
    Smart greenhouse fuzzy logic based control system enhanced with wireless data monitoring2016Inngår i: ISA transactions, ISSN 0019-0578, E-ISSN 1879-2022, Vol. 61, s. 297-307Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Greenhouse climate control is complicated procedure since the number of variables involved on it and which are dependent on each other. This paper presents a contribution to integrate greenhouse inside climate keys parameters, leading to promote a comfortable micro-climate for the plants growth while saving energy and water resources. A smart fuzzy logic based control system was introduced and improved through specific measure to the temperature and humidity correlation. As well, the system control was enhanced with wireless data monitoring platform for data routing and logging, which provides real time data access. The proposed control system was experimentally validated. The efficiency of the system was evaluated showing important energy and water saving.

  • 32.
    Azimoh, C. L.
    et al.
    University of Johannesburg, Department of Quality and Operations Management, Faculty of Engineering and Built Environment, Johannesburg, South Africa.
    Klintenberg, Patrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Mbohwa, C.
    University of Johannesburg, Department of Quality and Operations Management, Faculty of Engineering and Built Environment, Johannesburg, South Africa.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Replicability and scalability of mini-grid solution to rural electrification programs in sub-Saharan Africa2017Inngår i: Renewable Energy, ISSN 0960-1481, Vol. 106, s. 222-231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The assessment of off-grid electrification programs in developing countries largely based on mini-grid and solar home system (SHS) has shown that they are faced with low development imparts and sustainability challenges, which has resulted in failure of many projects. This study provides solutions on how to surmount these challenges, leaning on the experience of a hybrid solar-diesel mini-grid at Tsumkwe village in Namibia. It provides analyses of a case study based on empirical evidence from field studies, interviews of representatives of households, public institutions and energy providers. In addition, it investigates the technical challenges and economic impacts of the electrification program. HOMER™ and MATLAB™ models were used in the analysis and investigations. The findings show that despite the challenges, the system has been sustained because it keyed into an existing structure with growth potentials. The progressive tariff system adopted by the government helped to cushion costs and allow low income households in the energy matrix. Adoption of strict maintenance measures, and implementation of energy efficiency measures prior to the commissioning of the program, resulted in the reduction of costs. The success elements identified in this study could be extrapolated in other sub-Saharan African countries if the challenges are properly addressed.

  • 33.
    Azimoh, Chukwuma Leonard
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Sustainability and development impacts of off-grid electrification in developing countries: An assessment of South Africa's rural electrification program2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Previous studies have shown that provision of sustainable electricity supply to rural households is essential to bring development to off-grid populations. For this reason, most developing countries put large efforts into rural electrification programs to stimulate development and reduce poverty. However, to be sustainable these programs need to recover costs, which poses a challenge to remote low income populations.  This often forces governments and other institutions involved in rural electrification to subsidize the electricity production. It also affects the choice of technology and places a barrier on the level of energy provided in line with the ability to pay for services. As a result of this, most programs have failed to achieve the desired objectives, as the technologies used often do not support income generating activities that could increase the payment capabilities of the beneficiaries and contribute to development.

    This thesis is focused on the rural electrification program of South Africa, the country in sub-Saharan Africa that has the highest access to electricity. It investigates the success elements that influence the sustainability of rural electrification programs and their contributions to socio-economic development. This was achieved by evaluating the South African program that provides solar home systems to off-grid communities, and a hybrid solar-wind mini-grid project in South Africa. The study also draw lessons from other rural electrification programs in neighbouring countries, i.e. an evaluation of a hybrid solar-diesel mini-grid system in Namibia, and a review of two systems, a hybrid solar-biomass mini-grid project in Botswana and a hydro mini-grid program in Lesotho. The study revealed that hydro based hybrid mini-grid systems provide the most cost effective way of bringing energy services to rural settlements. Regardless of technology, successful programs depend on adequate support from the government, implementation of a progressive tariff system that allows the high consuming high income earners and businesses, to cross subsidize the low consuming , low income users. It shows that it is more likely for rural electrification programs to survive if the design considers the existing businesses, population growth and the corresponding load increase. The thesis further shows that provision of sufficient energy to induce income generating activities is essential to decrease the need for subsidies and to ensure the sustainability of programs. In addition, availability of spare parts and a capable management team is essential for the successful operations and maintenance of these systems.

    Fulltekst (pdf)
    fulltext
  • 34.
    Azimoh, Chukwuma Leonard
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    The energy loss in guiding against equipment theft in Thlatlaganya Village, South Africa.2013Konferansepaper (Fagfellevurdert)
  • 35.
    Azimoh, Chukwuma Leonard
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Klintenberg, Patrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Karlsson, Björn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Illuminated but not electrified: An assessment of the impact of Solar Home System on rural households in South Africa2015Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 155, s. 354-364Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The introduction of the off-grid electrification program in South Africa using the Solar Home System (SHS) was a central component of the government policy aimed at bringing development to un-electrified households. An assessment of the performance of SHS in many countries provided little evidence to support the development impact of the system. The general perception is that the SHS program is wasting government funds and has no hope of achieving the set objectives. Previous scientific reports have concluded that SHS is the most viable technology for bringing about socio-economic development to rural households. Most of these conclusions have been based on one sided arguments and largely on anecdotal evidence. This study provides a pluralistic view of the subject from the perspective of the energy service companies (ESCOs) and the households using the equipment. The development impact of SHS is subjected to scientific analysis by investigating the economic and social dimensions of the program. Additionally, the sustainability of the South African SHS program is assessed by investigating the challenges facing the ESCOs and the households. The study reveals that illumination provided by SHS electricity has profound impact on the livelihoods of rural households. Due to the limited capacity of SHS for productive and thermal use, there are limited direct economic benefits to the households. The associated economic impact is peripheral to the secondary usage of SHS electricity. SHS has improved the productivity of small scale business owners who utilize the light from SHS to do business at night. Irregularities in payment of subsidy funds and energy bills, high operation cost, non-optimal use of SHS, grid encroachment, and lack of customer satisfaction contribute to make the business unsustainable for the ESCOs.

    Fulltekst (pdf)
    fulltext
  • 36.
    Azimoh, Chukwuma Leonard
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Klintenberg, Patrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Karlsson, Björn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    The burden of shading and location on the sustainability of South African solar home system program2015Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 75, s. 308-313Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most contributions on the issues of sustainability of rural electrification projects have focused on the technology and business models used to drive the projects. The issues of user education and environmental impact on the technology have received little attention, despite the fact that these challenges affect lives of projects after commissioning. The usage pattern of solar home systems (SHS) by most users that placed their solar panels close to obstructing objects, results in shading of the panels, and geographic location of households in the concession areas of the South African SHS program affects the performances of the system. The non-optimal use of SHS is mainly due to lack of user education. Therefore this paper reports on the impact of geographic location and shading of panels on the economics and technical performance of SHS. The study was done by investigating the performance of 75 WP solar panels operated at two sites in South Africa (Upington in Northern Cape Province and Thlatlaganya in Limpopo Province), the performance of an optimized shaded SHS and a non-shaded one was also investigated. The results show that both geographic location and shading compromise the performance of the systems, the energy output of a solar panel located at Upington is increased by 19% and the state of charge of the battery (SOC) increased by 6%, compared to the panel situated at Thlatlaganya village. Also the life span of the battery is increased by about one year. The SOC of the partially shaded SHS is reduced by 22% and loss of power to the load increased by 20%. The geographical location of the SHS concession areas in South Africa and lack of adherence to the manufacturer's installation specification affects the economics of SHS and the energy output vis-a-vis the sustainability of the program due to reduction in life cycle of the batteries. 

  • 37.
    Azimoh, Chukwuma Leonard
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Klintenberg, Patrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Karlsson, Björn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Mbohwa, Charles
    University of Johannesburg, South Africa.
    Electricity for development:: Mini-grid solution for rural electrificationin South Africa2016Inngår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, nr 110, s. 268-277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of most rural electrification programs in the developing world is to bring about socioeconomicdevelopment to households. Governments have put in place a number of measures to achievethis goal. Previous studies on rural electrification programs in developing countries show that solar homesystems and mini-grid systems are the dominant technologies. Assessments of a pilot hybrid mini-gridproject at Lucingweni village have concluded that mini-grid projects are not feasible due to high electricityproduction costs. As a result efforts toward rural electrification have been focused on the solar homesystem. Nevertheless, previous studies of the South African solar home system program have shown thatthe development objectives of the program are yet to be met more than a decade after commissioning.Therefore, this study investigates the viability of a hybrid mini-grid as a solution for rural developmentin South Africa. Investigations were based on Lucingweni and Thlatlaganya, two rural Villages where themini-grid and solar home system have been introduced. The mini-grid systems were designed taking intoconsideration available natural resources and existing load profiles. The results show that a village of 300households needs about 2.4 kW h/household/day of electricity to initiate and sustain income generatingactivities and that the solar home system is not capable of supporting this level of demand. We also showthat in locations with hydro resources, a hybrid mini-grid system has the most potential for meeting theenergy needs of the households in a cost effective manner. The assessment shows that with adequateplanning and optimization of available resources, the cost of electricity production can be reduced.

    Fulltekst (pdf)
    fulltext
  • 38.
    Azimoh, Chukwuma Leonard
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Klintenberg, Patrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Karlsson, Björn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    An assessment of unforeseen losses resulting from inappropriate use of solar home systems in South Africa2014Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 136, s. 336-346Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the challenges to the sustainability of the Solar Home System (SHS) electrification program in South Africa is equipment theft. In response to this, communities susceptible to solar panel theft resort to mounting their panels flat on the ground so they can be looked after during the day and taken indoors at night for safe keeping. Other households use their security lights to illuminate their environment and provide security for pole and roof mounted solar panels at night. These actions have consequential effects on the performance of the SHS. Several studies have detected resentment from households regarding the low power quality from these systems. Most scientific contributions on the issue of low power from SHS have focused on the challenges based on the technical designs of the systems. The power losses due to the usage pattern of the system has not received much attention. This study therefore reports on the technical losses as a result of the deviation from the designed and installed specification of the system by the users in order to protect their systems. It also investigates the linkage between the technical and economic losses which affects the sustainability of SHS program. A case study was performed in Thlatlaganya village within Limpopo province in South Africa. Technical analysis using PVSYST solar software revealed that the energy output and performance of the battery is compromised as a result of these practices. Economic analysis indicates that the battery life and the economics of owning and operating SHS are affected negatively. The study recommends solutions to mitigate these losses, and proposes a cost effective way of optimizing the operation of SHS using a Bench-Rack system for mounting solar panels.

    Fulltekst (pdf)
    fulltext
  • 39.
    Baheta, Aklilu
    et al.
    Universiti Teknologi PETRONAS, Seri Iskandar Perak, Malaysia.
    L. K., Peng
    Universiti Teknologi PETRONAS, Seri Iskandar Perak, Malaysia.
    Suleiman, Shaharin
    Universiti Teknologi PETRONAS, Seri Iskandar Perak, Malaysia.
    Fentaye, Amare Desalegn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Universiti Teknologi PETRONAS, Seri Iskandar Perak, Malaysia.
    CFD Analysis of Fouling Effects on Aerodynamics Performance of Turbine Blades2018Inngår i: Rotating Machineries:: Aspects of Operation and Maintenanc, Springer, 2018, s. 73-84Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Fouling on gas turbine blades is detrimental to process operation as it may, over a period of time, reduce the blade efficiency and consequently the turbine’s efficiency. With the limitation of today’s technology, experimental study or real-life observation of fouling in a gas turbine is beyond imagination of maintenance engineers. Hence, the effect of fouling cannot be fully quantified for the engineers to come out with mitigation or intervention plans. Nevertheless, computational fluid dynamics (CFD) may provide a good simulation to understand the phenomena. In this chapter, recent effort involving CFD study on the influence of fouling on gas turbine performance is presented. Firstly, the nature of fouling on the gas turbine and the general consequences are discussed. This is followed by an elaboration on how CFD study has been conducted by the authors. Finally, the findings from the study are discussed.

  • 40.
    Bai, Fan
    et al.
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian 710049, Shaanxi, Peoples R China..
    Lei, Le
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian, Shaanxi, Peoples R China..
    Zhang, Zhuo
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian, Shaanxi, Peoples R China..
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Chen, Li
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian, Shaanxi, Peoples R China..
    Dai, Yan-Jun
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian, Shaanxi, Peoples R China..
    Chen, Lei
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian, Shaanxi, Peoples R China..
    Tao, Wen-Quan
    Xi An Jiao Tong Univ, Key Lab Thermofluid Sci & Engn MOE, Xian, Shaanxi, Peoples R China..
    Application of similarity theory in modeling the output characteristics of proton exchange membrane fuel cell2021Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 46, nr 74, s. 36940-36953Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proton Exchange Membrane Fuel Cell (PEMFC) has attracted widespread interest. In the present work, similarity analysis is adopted for a three-dimensional single-phase isothermal model of PEMFC to derive similarity criteria. Seven kinds of input criteria (Pi(1) similar to Pi(7)) are obtained, relevant to the fluid flow, pressure drop, flow resistance in a porous medium, activity loss, diffusion mass transfer, convective mass transfer and ohmic loss in PEMFC respectively. Dimensionless voltage and dimensionless current density are defined as two output criteria. Numerical verifications show that if the seven criteria keep their individual values with their components vary in a wide range, the dimensionless polarization curves keep the same with a deviation about 1%, showing the validity and feasibility of the present analysis. From the effect on the dimensionless polarization curve, sensibility analysis shows that the seven criteria can be divided into three categories: strong (Pi(4) and Pi(7), -94.9% similar to +349.2%), mild to minor (Pi(5) and Pi(6), -4.5% similar to +5.0%), and negligible (Pi(1), Pi(2) and Pi(3), -1.2% similar to +1.1%). The similarity analysis approach can greatly save computation time in modeling the output characteristics of PEMFC. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

  • 41.
    Bai, Q.
    et al.
    Xi'an Jiaotong University, Xi'an, China.
    Guo, Z.
    Xi'an Jiaotong University, Xi'an, China.
    Cui, X.
    Xi'an Jiaotong University, Xi'an, China.
    Yang, Xiaohu
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Xi'an Jiaotong University, Xi'an, China.
    Yanhua, L.
    Xi'an Jiaotong University, Xi'an, China.
    Jin, L.
    Xi'an Jiaotong University, Xi'an, China.
    Sun, Y.
    Xi'an Jiaotong University, Xi'an, China.
    Experimental investigation on the solidification rate of water in open-cell metal foam with copper fins2018Inngår i: Energy Procedia, Elsevier Ltd , 2018, s. 210-214Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study focused on the effect of inserting fins into metal foam on the solidification rate. To this aim, a well-designed experimental system with solid-liquid interface visualization was built. Metal foam samples with different fin intervals were prepared for experiments. Solidification process of water saturating in finned metal foam under bottom cooling was experimentally investigated. Results showed that inserting fins into metal foam can make a promotional improvement on solidification rate of water. The solid-liquid interface became curved after inserting fins, compared with metal foam sample without fins. Besides, changing the interval has little effect on the solidification rate.

  • 42.
    Bai, Q.
    et al.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Guo, Z.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yang, Xiaohu
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jin, L.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology (KTH), Stockholm, Sweden.
    Experimental investigation on the solidification behavior of phase change materials in open-cell metal foams2017Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 142, s. 3703-3708Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presented an experimental investigation on solidification behavior of fluid saturated in highly porous open-cell copper foams. Particular attention has been made on the effect of pore parameters (pore density and porosity) on the solidification behavior. A purposely-designed apparatus was built for experimental observations. Results showed that the copper foam had a great effect on solidification and the full solidification time can be saved up to 50%, especially preventing the decrease in solidification rate during the later stage of phase change. The smaller the porosity is, the faster the solidification rate will be. Pore density was found to have little influence upon the solidification rate. In addition, the local natural convection does exist but it has a slight effect on solidification, leading to the slant of the solid-liquid interface. 

  • 43.
    Bales, Chris
    et al.
    Högskolan Dalarna, Energi och miljöteknik.
    Nielsen, Christian
    Högskolan Dalarna, Energi och miljöteknik.
    Peréz de la Mora, Nicolás
    SAMPOL Ingeniería y Obras / Palma de Mallorca (Spain).
    Sotnikov, Artem
    Vela Solaris AG, Winterthur (Switzerland).
    Louvet, Yoann
    FSAVE Solartechnik GmbH, Kassel (Germany).
    Bava, Federico
    Technical University of Denmark, Lyngby (Denmark).
    Shantia, Alireza
    University of Innsbruck, Innsbruck (Austria).
    Lennermo, Gunnar
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. WSP, Gothenburg (Sweden).
    Seven Phd Studies on Solar District Heat2014Inngår i: Proceedings EuroSun 2014 / ISES Conference Proceedings (2014), ISES , 2014, s. 652-661Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The Solar Heat Integration NEtwork (SHINE) is a European research school in which 13 PhD students in solar thermal technologies are funded by the EU Marie-Curie program. It has five PhD course modules as well as workshops and seminars dedicated to PhD students both within the project as well as outside of it. The SHINE research activities focus on large solar heating systems and new applications: on district heating, industrial processes and new storage systems. The scope of this paper is on systems for district heating for which there are six PhD students, three at universities and two at companies. In addition there is a seventh PhD in a Swedish national research school focused on energy efficiency within district heating networks (Reesbe). The initial work has concentrated on literature studies and on setting up initial models and measurement setups to be used for validation purposes. Some results of these studies are presented in the paper. The PhD students will complete their studies in 2017-18.

  • 44.
    Bao, Minglei
    et al.
    Zhejiang Univ, Coll Elect Engn, Hangzhou 310058, Peoples R China..
    Ding, Yi
    Zhejiang Univ, Coll Elect Engn, Hangzhou 310058, Peoples R China..
    Sang, Maosheng
    Zhejiang Univ, Coll Elect Engn, Hangzhou 310058, Peoples R China..
    Li, Daqing
    Beihang Univ, Sch Reliabil & Syst Engn, Beijing 100191, Peoples R China..
    Shao, Changzheng
    Zhejiang Univ, Coll Elect Engn, Hangzhou 310058, Peoples R China..
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Inst Technol, Sch Chem Sci & Engn, Stockholm, Sweden..
    Modeling and evaluating nodal resilience of multi-energy systems under windstorms2020Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 270, artikkel-id UNSP 115136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the growing frequency and extent of extreme weather events, the resilient operation of multi-energy systems (MESs) has drawn attention nowadays. However, there is little study on the methodology with a set of key indicators to quantify the resilience of MESs with the consideration of the impacts of extreme weather. To address the problem, this paper proposes a framework to evaluate the time-dependent resilience of MESs considering energy interactions during extreme weather events, such as windstorms. Firstly, the multi-phase performance curve is utilized to describe the response behavior of MESs at different phases under the impacts of windstorms. Secondly, a service-based optimal energy flow model is developed to minimize the consequences caused by windstorms through the coordination among different energy subsystems. In order to model the chaotic failures and restoration of components, the Monte-Carlo simulation technique is applied. Furthermore, nodal resilience metrics for different energy carriers are proposed to quantify the resilience in MESs. Numerical studies demonstrate the capability of the proposed technique to quantify the resilience of MESs under windstorms. The results show that the resilience performance level of MESs can differ in different regions with the impacts of windstorms. The findings can provide a useful reference for system operators to constitute targeted resilience improvement measures.

  • 45. Beckinghausen, A.
    et al.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    From removal to recovery: An evaluation of nitrogen recovery techniques from wastewater2020Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 263, artikkel-id 114616Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitrogen recovery is the next step in the improvement of the wastewater treatment process, utilizing this important nutrient for fertilizers to decrease use of energy, petrochemicals, and impact on the environment. The majority of wastewater treatment plants currently employ methods to remove nitrogen which are energy intensive and have no additional benefits besides complying with effluent concentration limits. Instead, recovering nitrogen allows simultaneous treatment of wastewater while collecting a concentrated ammonia product, creating a circular economy solution. This review acts to compile current research regarding nitrogen recovery and compare different techniques' recovery efficiencies and energy requirements. One outcome of this review is that more than one third of the techniques reviewed had little comments around the energy question, and thus more research needs to take place as these recovery systems continue to evolve towards full scale implementation. Additionally, a basic economic analysis was completed to demonstrate potential investment opportunities to implement these technologies. From this investigation, gas permeable membrane technology has the potential to recover ammonia from wastewater using little energy and may provide a small income with the sale of the product. Other techniques such as vacuum membrane distillation with acid absorption need further validation to determine the energy costs, as the amount of heat recycling has a great impact on the overall energy and economic balances. Finally, a discussion of the misalignment of products from recovery techniques and fertilizers in use today highlights the lack of communication and information sharing between the research community and the end users. 

  • 46.
    Beckinghausen, Aubrey
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Reynders, Jonathan
    Univ Pretoria, Dept Chem Engn, Hatfield, South Africa..
    Merckel, Ryan
    Univ Pretoria, Dept Chem Engn, Hatfield, South Africa..
    Wu, Yun Wen
    Univ Pretoria, Dept Chem Engn, Hatfield, South Africa..
    Marais, Heidi
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Post-pyrolysis treatments of biochars from sewage sludge and A. mearnsii for ammonia (NH4-n) recovery2020Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 271, artikkel-id UNSP 115212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    NH4-N-loaded biochars are suitable candidates for soil amendment and fertilization. Sewage sludge-based biochar and biochar from the invasive species black wattle were used as sorbents for the adsorption of ammonia from a concentrated solution to mimic the wastewater treatment plant reject water stream. To increase ammonium recovery efficiency, two post-pyrolysis activation techniques were compared: steam activation and hydrogen peroxide treatment. It was found that the success of the treatment options was material dependent; therefore, post-pyrolysis treatments will require optimization for different applications based on feedstock. A simplified version of an adsorption process simulated in Aspen Tech predicts that NH4-N may be recovered at an energy cost lower than that of the Haber-Bosch process for black wattle biochar yields of below 19.5%. The biooil and syngas produced during pyrolysis can be used to lessen the energy requirements of the process, so that the solid portion may be utilized as an adsorbent and soil fertilizer. The energy-based sustainability of this technology warrants a more in-depth investigation for evaluation of the techno-economic feasibility for this class of loaded sorbents, and whether this method of nitrogen capture from wastewater is a suitable replacement of the costly Haber-Bosch process.

  • 47.
    Belhomme, Regine
    et al.
    Elect France, Palaiseau, France..
    Corsetti, Edoardo
    Ric Sistema Energet, Milan, Italy..
    Gutschi, Christoph
    CyberGRID, Vienna, Austria..
    Kessels, Kris
    Vlaamse Instelling Technol Onderzoek, Genk, Belgium..
    Virag, Ana
    Vlaamse Instelling Technol Onderzoek, Genk, Belgium..
    Qadrdan, Meysam
    Cardiff Univ, Cardiff, Wales..
    Xu, Xiandong
    Cardiff Univ, Cardiff, Wales..
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jurasz, Jakob
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bottom-Up Flexibility in Multi-Energy Systems: Real-World Experiences From Europe2021Inngår i: IEEE Power and Energy Magazine, ISSN 1540-7977, E-ISSN 1558-4216, Vol. 19, nr 4, s. 74-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electricity Systems in europe are experiencing major changes due to targets for renewable energy integration, reducing greenhouse gas emissions, and energy efficiency. Different studies show that there is a growing need for more flexibility and active stakeholder involvement at all levels (from small consumers to pan-European networks) to ensure the efficient and reliable operation of the electricity system, particularly to deal with growing volumes of renewable energy sources, from transmission-level wind and solar farms to household-level photovoltaic generation. Other key evolutions that aim to decarbonize the energy sector beyond electricity, such as those based on the electrification of energy end uses (e.g., the development of electric vehicles and the electrification of heating), are also expected to have a substantial impact.

  • 48.
    Benavente, F.
    et al.
    Department of Chemical Engineering, Applied Electrochemistry, KTH Royal Institute of Technology, Stockholm, Sweden.
    Anders, Lundblad
    Division of Safety and Transport/Electronics, RISE, Research Institutes of Sweden, Borås, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Department of Chemical Engineering, Applied Electrochemistry, KTH Royal Institute of Technology, Stockholm, Sweden.
    Zhang, Y.
    Department of Chemical Engineering, Applied Electrochemistry, KTH Royal Institute of Technology, Stockholm, Sweden.
    Cabrera, S.
    Instituto de Investigaciones Químicas, Carrera de Ciencias Químicas, UMSA Universidad Mayor de San Andrés, Bolivia.
    Lindbergh, G.
    Department of Chemical Engineering, Applied Electrochemistry, KTH Royal Institute of Technology, Stockholm, Sweden.
    Photovoltaic/battery system sizing for rural electrification in Bolivia: Considering the suppressed demand effect2019Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 235, s. 519-528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rural electrification programs usually do not consider the impact that the increment of demand has on the reliability of off-grid photovoltaic (PV)/battery systems. Based on meteorological data and electricity consumption profiles from the highlands of Bolivian Altiplano, this paper presents a modelling and simulation framework for analysing the performance and reliability of such systems. Reliability, as loss of power supply probability (LPSP), and cost were calculated using simulated PV power output and battery state of charge profiles. The effect of increasing the suppressed demand (SD) by 20% and 50% was studied to determine how reliable and resilient the system designs are. Simulations were performed for three rural application scenarios: a household, a school, and a health centre. Results for the household and school scenarios indicate that, to overcome the SD effect, it is more cost-effective to increase the PV power rather than to increase the battery capacity. However, with an increased PV-size, the battery ageing rate would be higher since the cycles are performed at high state of charge (SOC). For the health centre application, on the other hand, an increase in battery capacity prevents the risk of electricity blackouts while increasing the energy reliability of the system. These results provide important insights for the application design of off-grid PV-battery systems in rural electrification projects, enabling a more efficient and reliable source of electricity.

  • 49.
    Benavente-Araoz, F.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Anders, Lundblad
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zhang, Y.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Cabrera, S.
    UMSA Universidad Mayor de San Andrés, Bolivia.
    Lindbergh, G.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Loss-of-load probability analysis for optimization of small off-grid PV-battery systems in Bolivia2017Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 142, s. 3715-3720Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluates the use of energy storage technologies coupled to renewable energy sources in rural electrification as a way to address the energy access challenge. Characteristic energy demanding applications will differently affect the operating conditions for off-grid renewable energy systems. This paper discusses and evaluates simulated photovoltaic power output and battery state of charge profiles, using estimated climate data and electricity load profiles for the Altiplanic highland location of Patacamaya in Bolivia to determine the loss of load probability as optimization parameter. Simulations are performed for three rural applications: household, school, and health center. Increase in battery size prevents risk of electricity blackouts while increasing the energy reliability of the system. Moreover, increase of PV module size leads to energy excess conditions for the system reducing its efficiency. The results obtained here are important for the application of off-grid PV-battery systems design in rural electrification projects, as an efficient and reliable source of electricity.

  • 50. Berkqvist, Julia
    et al.
    Johansson, Joakim
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Industriell ekonomi och organisation.
    Annie Lööf i svenska tidningsmedier - en diskursanalys2019Inngår i: Statsvetenskaplig Tidskrift, ISSN 0039-0747, nr 2, s. 241-272Artikkel i tidsskrift (Fagfellevurdert)
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