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  • 151.
    Gao, X.
    et al.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Wei, P.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Xie, Y.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Zhang, S.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Niu, Z.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Lou, Y.
    School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    Yang, Xiaohu
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology (KTH), Stockholm, Sweden; School of Human Settlements and Civil Engineering, Xi'An Jiaotong University, Xi'an, China.
    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 of the cubic thermal energy storage unit with coil tubes2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, s. 3709-3714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presented experimental investigations on the thermal performance of a thermal energy storage (TES) unit with coil tubes. A designed test rig was built and the melting heat transfer characteristics (melting front and temperature distribution) inside the TES unit were examined. The effects of charging flow rate on the overall phase change process were examined. The results showed that natural convection accelerated the thermal energy transport in the melt phase in the top region, but weakened the heat transfer in the bottom region; this resulted in the unmelt PCM at the bottom. The melting heat transfer was overall enhanced by the increase in inlet flow rate, indicating that the full charging time can be shortened by a larger flow rate. 

  • 152.
    Ghaviha, Nima
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Increasing Energy Efficiency in Electric Trains Operation: Driver Advisory Systems and Energy Storage2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Electric traction is the most efficient traction system in the railway transportation. However, due to the expensive infrastructure and high power demand from the grid, the share of electric trains in the railway transportation is still lower than other trains. Two of the possible solutions to increase the share of electric trains are: optimal train operation to minimize energy consumption, the use of batteries as the energy source for driving electric trains on non-electrified lines. This thesis aims to extend the knowledge in the field of energy optimal operation of electric trains and battery-driven electric trains.

    Energy optimal operation of electric trains is supervised using a driver advisory system (DAS), which instructs the driver to operate the train in an energy-efficient manner. This thesis contributes to DAS technology under two topics: the increase of energy efficiency and the design of DAS.

    This thesis presents a complete procedure of designing a DAS from the mathematical formulation to application on the train. The designed DAS is in the form of an Android application and is based on a dynamic programming approach. The computational performance of the approach is enhanced using heuristic state reducing rules based on the physical constraints of the system. The application of the DAS shows a potential reduction of 28% in energy consumption.

    This thesis considers the detailed energy losses in the whole propulsion system using a regression model that is generated from validated physical models. The application of the regression model instead of a previous constant efficiency factor model results in 2.3% reduction in energy consumption of the optimum speed profiles.

    Based on the solution for the normal electric trains, a solution is also offered for the optimal operation of battery-driven electric trains, in which the characteristics of the battery as one of the main components are considered using an electrical model. The solution presented in this thesis, is to combine the popular single mass point train model with an electrical circuit battery model.

    Furthermore, this thesis evaluates the performance of the optimization approaches and validates the models against the measurements from actual drives of a real-life battery train. The results show a potential of around 30% reduction in the charge consumption of the battery.

    The results of this thesis (algorithms and the Android application) are provided as open source for further research in the field of energy efficient train control.

  • 153.
    Ghaviha, Nima
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bohlin, M.
    RISE SICS, Västerås, Sweden.
    Holmberg, C.
    Bombardier Transportation, Västerås, Swede.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Skoglund, Robert
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jonasson, Daniel
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    A driver advisory system with dynamic losses for passenger electric multiple units2017Ingår i: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 85, s. 111-130Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Driver advisory systems, instructing the driver how to control the train in an energy efficient manner, is one the main tools for minimizing energy consumption in the railway sector. There are many driver advisory systems already available in the market, together with significant literature on the mathematical formulation of the problem. However, much less is published on the development of such mathematical formulations, their implementation in real systems, and on the empirical data from their deployment. Moreover, nearly all the designed driver advisory systems are designed as an additional hardware to be added in drivers’ cabin. This paper discusses the design of a mathematical formulation and optimization approach for such a system, together with its implementation into an Android-based prototype, the results from on-board practical experiments, and experiences from the implementation. The system is based on a more realistic train model where energy calculations take into account dynamic losses in different components of the propulsion system, contrary to previous approaches. The experimental evaluation shows a significant increase in accuracy, as compared to a previous approach. Tests on a double-track section of the Mälaren line in Sweden demonstrates a significant potential for energy saving.

  • 154.
    Ghaviha, Nima
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Mälardalen University.
    Bohlin, Markus
    Research Institutes of Sweden RISE SICS Västerås.
    Holmberg, Christer
    Bombardier Transportation.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Speed Profile Optimization of Catenary-free Electric Trains with Lithium-ion BatteriesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Catenary-free operated electric trains, as one of the recent technologies in railwaytransportation, has opened a new field of research: speed profile optimization and energy optimaloperation of catenary-free operated electric trains. A well-formulated solution for this problem shouldconsider the characteristics of the energy storage device using a validated model and method. This paper,discusses the consideration of the battery behavior in the problem of speed profile optimization ofcatenary-free operated electric trains. We combine the single mass point train model with an electricalbattery model and apply a dynamic programming approach to minimize the charge taken from thebattery during the catenary-free operation. The models and the method are validated and evaluatedagainst experimental data gathered from the test runs of an actual battery driven train tested in Essex,UK. The results show a significant potential in energy saving. Moreover, we show that the optimumspeed profiles generated using our approach consume less charge from the battery compared to theprevious approaches.

  • 155.
    Ghaviha, Nima
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bohlin, Markus
    SICS Swedish ICT, Sweden.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Optimal Control of an EMU Using Dynamic Programming2015Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, s. 1913-1919Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A model is developed for minimizing the energy consumption of an electric multiple unit through optimized driving style, based on Hamilton-Jacobi-Bellman equation and Bellman's backward approach. Included are the speed limits, track profile (elevations), different driving modes and the train load. This paper includes aspects like the power loss in the auxiliary systems, time management, validation of the model regarding energy calculations and a study on discretization and the accuracy of the model. The model will be used as a base for a new driver advisory system. 

  • 156.
    Ghaviha, Nima
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Holmberg, C.
    Bombardier Transportation, Västerås, Sweden.
    Bohlin, M.
    RISE SICS, Västerås, Sweden.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Modeling of Losses in the Motor Converter Module of Electric Multiple Units for Dynamic Simulation Purposes2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, s. 2303-2309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulation of power consumption in electric trains is categorized in two categories: electrical power simulation and mechanical power simulation. The mechanical power is calculated as speed times tractive effort and it gives an overall view on the total energy consumption of the train during different driving cycles. Detailed calculation of losses in different components in the propulsion system is however done using complex electrical models. In this paper, we introduce a nonlinear regression model generated from validated electrical equations for the calculation of the power loss in the motor converter module of electric trains. The function can be used instead of efficiency maps to evaluate the trains’ performance during the operation or dynamic simulations.

  • 157.
    Gholinejad, Hassan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Mousavi Takami, Kourosh
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Estimation of electricity losses by numerical approach to present a solution for losses reduction2014Ingår i: International Journal of Advanced Engineering Applications, ISSN 2321-7723, Vol. 7, nr 4, s. 30-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electricity losses are one of the big anxieties for utilities. Electricity loss in Iran network according to Tavanir report is over 15% but individual researchers have different comments. Also, the lack of sufficient information is a network problem. To overcome on the problems authors used Top-Down/Bottom-Up method to estimate of losses in Iran’s electricity network. To achieve the model, at a certain moment measurements of input complex power in the feeder and voltages in the farthest network node and power flow calculation has been done. Using the estimated losses, authors suggest a strategy to losses reduction in every different part of distribution networks. Due to different culture, climate and network topology, losses are different and separate solution is needed. Proposed method was carried out by performing tests on a feeder with 88+35 nodes according to the IEEE 123 node test feeder. An economical investigation showed the benefits for utilities and improved the proposed plan. The main innovation in the presented paper is to combine a forecasting approach with experimental data to define a model for networks with unknown parameters.

  • 158.
    Gholinejad, Hassan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Mousavi Takami, Kourosh
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Mousavi Takami, Amin
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    To promote electricity smart grid performances by numerical modeling applications2014Ingår i: Proceedings of the 55th Conference on Simulation and Modelling(SIMS 55): “Modelling, Simulation and Optimization” / [ed] Alireza Rezania Kolai, Kim Sørensen & Mads Pagh Nielsen, Linköping: Linköping University Electronic Press, 2014, s. 347-355Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wide world’s utilities are generating, transmitting and distributing of electricity throughout the country andare responsible to its quality.Distributed automated distribution system has been proposed for planning to reduce losses, optimize capacityand load balancing in electricity networks. The world electricity average loss is about and outage percustomer time is about min/ year. The indices are needed to optimize in developing countries.This paper deals on a modeled distribution system in Sari distribution region and evaluates three mentionedparameters on network quality. Restoration, maneuvers to achieve the minimum loss, reactive powercontrolling, load balancing etc are investigated.Modeling performs by MATLAB software, EMTP for transient modeling and Digsilent with real data bySari Distribution Company. In this paper, a new approach by rearrangement aimed at reducing losses andimproving of load balancing in distribution networks was presented.

    Keywords: Modelling, smart grid, electricity network

  • 159.
    Goldberg, C.
    et al.
    Cranfield University, Bedfordshire, United Kingdom.
    Nalianda, D.
    Cranfield University, Bedfordshire, United Kingdom.
    Sethi, V.
    Cranfield University, Bedfordshire, United Kingdom.
    Pilidis, P.
    Cranfield University, Bedfordshire, United Kingdom.
    Singh, R.
    Cranfield University, Bedfordshire, United Kingdom.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Assessment of an energy-efficient aircraft concept from a techno-economic perspective2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 221, s. 229-238Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An increase in environmental awareness in both the aviation industry and the wider global setting has led to large bodies of research dedicated to developing more sustainable technology with a lower environmental impact and lower energy usage. The goal of reducing environmental impact has necessitated research into revolutionary new technologies that have the potential to be significantly more energy efficient than their predecessors. However, for innovative technologies in any industry, there is a risk that adoption will be prohibitively expensive for commercial application. It is therefore important to model the economic factors of the new technology or policy at an early stage of development. This research demonstrates the application of a Techno-economic Environmental Risk Assessment framework that may be used to identify the economic impact of an energy-efficient aircraft concept and the impact that environmental policy would have on the viability of the concept. The framework has been applied to a case study aircraft designed to achieve an energy saving of 60% in comparison to a baseline 2005 entry-into-service aircraft. The model compares the green aircraft concept to a baseline conventional aircraft using a sensitivity analysis of the aircraft direct operating cost to changes in acquisition and maintenance cost. The research illustrates an economically viable region for the technology. Cost margins are identified where the increase in operating cost due to expensive novel technology is counterbalanced by the reduction in cost resulting from low energy consumption. Viability was found to be closely linked to fuel price, with a low fuel price limiting the viability of energy-efficient aviation technology. In contrast, a change in environmental taxation policy was found to be beneficial, with the introduction of carbon taxation incentivising the use of an environmentally optimised aircraft.

  • 160.
    Guezgouz, M.
    et al.
    Department of Electrical Engineering, Mostaganem University, Mostaganem, Algeria.
    Jurasz, Jakob
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Faculty of Management, Department of Engineering Management, AGH University.,Cracow, Poland.
    Bekkouche, B.
    Department of Electrical Engineering, Mostaganem University, Mostaganem, Algeria.
    Ma, T.
    School of Mechanical Engineering, Shanghai Jiao Tong University, China.
    Javed, M. S.
    School of Mechanical Engineering, Shanghai Jiao Tong University, China.
    Kies, A.
    Frankfurt Institute for Advanced Studies, Goethe University Frankfurt, Frankfurt am Main, Germany.
    Optimal hybrid pumped hydro-battery storage scheme for off-grid renewable energy systems2019Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 199, artikel-id 112046Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of energy storage systems paves the way towards a high integration of renewable energy sources in the electricity generation sector. Considering above, this paper introduces a new energy management strategy to efficiently coordinate a hybrid energy storage system based on pumped hydro storage (long term bulk storage) with batteries (short term, more flexible). For the purpose of this analysis, hourly time series of irradiation, wind speed, temperature and real measured load (characteristic for farmstead) covering one year were gathered for the selected site in Algeria. The optimal size of the system is determined based on a multi-objective optimization using a grey wolf optimizer implemented in MATLAB software. The results indicate that the hybrid storage system enables achieving higher reliability at lower cost in comparison to a system with single storage technology. The use of hybrid storage also reduces the curtailment of renewable generation. Further findings reveal that the cost of an optimal energy supply system with 97.5% reliability is 0.162 €/kWh, 0.207 €/kWh and 1.462 €/kWh for hybrid storage, battery and pumped storage, respectively. However, sensitivity analysis shows that the optimal hybrid storage configuration is less resilient when changes in irradiation/temperature/load are considered. This indicates that special actions (upscale of installed power) must be undertaken to avoid lower performance of hybrid storage systems. In summary, the hybrid storage system seems to be better sized for consideration in optimized solar/wind conditions, but by avoiding oversizing they are less resilient to future potential changes in renewable energy availability.

  • 161.
    Guezgouz, M.
    et al.
    Mostaganem University, Algeria.
    Jurasz, Jakub
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. AGH University of Science and Technology, Cracow, Poland.
    Bekkouche, B.
    Mostaganem University, Algeria.
    Techno-economic and environmental analysis of a hybrid PV-WT-PSH/BB standalone system supplying various loads2019Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 3, artikel-id 514Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Algerian power system is currently dominated by conventional (gas- and oil-fueled) power stations. A small portion of the electrical demand is covered by renewable energy sources. This work is intended to analyze two configurations of renewables-based hybrid (solar–wind) power stations. One configuration was equipped with batteries and the second with pumped-storage hydroelectricity as two means of overcoming: the stochastic nature of the two renewable generators and resulting mismatch between demand and supply. To perform this analysis, real hourly load data for eight different electricity consumers were obtained for the area of Mostaganem. The configuration of hybrid power stations was determined for a bi-objective optimization problem (minimization of electricity cost and maximization of reliability) based on a multi-objective grey-wolf optimizer. The results of this analysis indicate that, in the case of Algeria, renewables-based power generation is still more expensive than electricity produced from the national grid. However, using renewables reduces the overall CO 2 emissions up to 9.3 times compared to the current emissions from the Algerian power system. Further analysis shows that the system performance may benefit from load aggregation. 

  • 162.
    Guo, K.
    et al.
    University of Stavanger, Stavanger, Norway.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yu, Z.
    University of Stavanger, Stavanger, Norway.
    In-situ heavy and extra-heavy oil recovery: A review2016Ingår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 185, s. 886-902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to the growing global energy demand and increasingly limited availability of conventional or easy-to-produce crude oils, extensive attention is being paid to the exploitation of unconventional heavy and extra-heavy oils. However, their inherent properties, characterized by high viscosity and poor mobility, coupled with the complex reservoir configuration, make the desired recovery processes very challenging. Although several in-situ recovery techniques have been employed in oil reservoirs worldwide, most of them are still suffering from low sweep and displacement efficiencies, high capital investment, potential formation damage and negative environmental footprints. This paper aims to provide a comprehensive review of the existing in-situ heavy oil recovery techniques, which fall into three categories of thermal injection, chemical injection and gas injection. Different aspects including the fundamental principles, main features, applicability, and limitations of these recovery processes are elaborated sequentially to illustrate the current technology status. Underlying mechanisms causing the relatively low recovery factors will also be pinpointed. Furthermore, this paper focuses on the technology using novel and active catalysts for simultaneous heavy oil upgrading and recovery, especially in the case of metallic nanocatalysts. Rationales, advantages and challenges regarding this in-situ catalytic upgrading technology will be extensively described for their potential implementation in fields. It is noteworthy that many recovery techniques are still limited to the laboratory scale with needs for further investigations. Therefore, this paper also covers the evaluation standards and analytical methodologies of heavy and extra-heavy oil recovery to establish experimental screening criteria. In the end, economic and environmental aspects of the in-situ catalytic upgrading technology have been briefly discussed. The objective of this review is to present a wide range of expertise related to the in-situ heavy oil recovery processes, and to introduce the in-situ catalytic upgrading technology as an effective and environmental friendly heavy oil recovery process.

  • 163.
    Guo, K.
    et al.
    Univ Stavanger, Norway.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yu, Zhixin
    Univ Stavanger, Norway.
    Size-Dependent Catalytic Activity of Monodispersed Nickel Nanoparticles for the Hydrolytic Dehydrogenation of Ammonia Borane2018Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 1, s. 517-525Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nickel (Ni) nanoparticles (NPs) with controlled sizes in the range of 4.9-27.4 nm are synthesized by tuning the ratio of the nickel acetylacetonate precursor and trioctylphosphine in the presence of oleylamine. X-ray diffraction and transmission electron microscopy confirm the formation of the metallic Ni crystal phase and their monodispersed nature. These Ni NPs are found to be effective catalysts for the hydrolytic dehydrogenation of ammonia borane, and their catalytic activities are size-dependent. A volcano-type activity trend is observed with 8.9 nm Ni NPs presenting the best catalytic performance. The activation energy and turnover frequency (TOF) of the 8.9 nm NP catalyst are further calculated to be 66.6 kJ·mol-1 and 154.2 molH2·molNi -1·h-1, respectively. Characterization of the spent catalysts indicates that smaller-sized NPs face severe agglomeration, resulting in poor stability and activity. Three carbon support materials are thus used to disperse and stabilize the Ni NPs. It shows that 8.9 nm Ni NPs supported on Ketjenblack (KB) exhibit higher activity than that supported on carbon nanotubes and graphene nanoplatelets. The agglomeration-induced activity loss is further illustrated by immobilizing 4.9 nm Ni NPs onto KB, which exhibits significantly enhanced activity with a high TOF of 447.9 molH2·molNi -1·h-1 as well as an excellent reusability in the consecutive dehydrogenation of ammonia borane. The high catalytic performance can be attributed to the intrinsic activity of nanoparticulate Ni and the improved activity and stability due to the strong Ni/KB metal-support interactions.

  • 164.
    Guo, Kun
    et al.
    Univ Stavanger, Dept Petr Engn, N-4036 Stavanger, Norway.;Univ Stavanger, Natl IOR Ctr Norway, N-4036 Stavanger, Norway..
    Hansen, Vidar Folke
    Univ Stavanger, Dept Mech & Struct Engn & Mat Sci, N-4036 Stavanger, Norway..
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Malardalen Univ, Dept Energy Bldg & Environm, S-72123 Vasteras, Sweden..
    Yu, Zhixin
    Univ Stavanger, Dept Petr Engn, N-4036 Stavanger, Norway.;Univ Stavanger, Natl IOR Ctr Norway, N-4036 Stavanger, Norway..
    Monodispersed nickel and cobalt nanoparticles in desulfurization of thiophene for in-situ upgrading of heavy crude oil2018Ingår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 211, s. 697-703Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monodispersed nickel (Ni) and cobalt (Co) nanoparticles (NPs) with different sizes are synthesized via the thermal decomposition of organometallic precursors by controlling the reaction temperature and surfactant amount. X-ray diffraction analysis of the as-prepared NP samples shows the formation of cubic Ni metal phases with good crystallinity, while the cubic Co metal samples are semi-amorphous. Transmission electron microscopy characterization further confirms that two Ni NP samples with average sizes of 9 and 27 nm, and Co NPs with an average size of 6 nm are successfully prepared with a narrow size distribution. Furthermore, catalytic performance of these monodispersed NPs towards the hydrodesulfurization (HDS) reaction, which plays a pivotal role in the upgrading of heavy crude oil, is evaluated under reservoir-relevant conditions using thiophene as a sulfur-containing model compound. Different parameters including particle size, catalyst dosage, hydrogen donor ratio, temperature, and reaction duration are systematically studied to optimize the catalytic HDS performance. The morphology and size of the spent NP catalysts after the reaction are also analyzed. The results show that the 9 nm Ni NPs exhibit the best HDS activity and stability compared with other catalysts, which suggests that such well-dispersed Ni NPs are promising candidates for the in-situ upgrading and recovery of heavy crude oil from underground reservoirs.

  • 165.
    Guo, Kun
    et al.
    Univ Stavanger, Norway.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yu, Zhixin
    Univ Stavanger, Norway.
    Metallic nanoparticles for enhanced heavy oil recovery: promises and challenges2015Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, s. 2068-2073Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the increasing global energy demand, great attention has been focused on utilizing heavy oil and bitumen, which are potentially located ultra-deep underground and cannot be easily recovered. Numerous recovery approaches have been proposed for successful extraction of heavy hydrocarbons from ultra-deep reservoirs. However, these approached are often accompanied by high energy consumption, large amounts of wastewater generation, and undesirable environmental damage. Nanotechnology has appeared as one of the promising technologies for in-situ heavy oil recovery, e.g., employing metal-based nanoparticles. In this article, we provide a brief overview of metallic nanoparticles for in-situ enhanced recovery of heavy oil. It gives a general introduction of the potential advantages of nanoparticle catalysts for heavy oil recovery and illustrates the improved recovery mechanism. Some technology challenges related to this promising technology will also be pinpointed. These technology challenges need to be solved through further research and development before field applications. 

  • 166. Guo, S.
    et al.
    Li, Hailong
    Zhao, J.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Numerical simulation of the direct contact mobilized thermal energy storage2012Konferensbidrag (Refereegranskat)
  • 167.
    Guo, S.
    et al.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Liu, Q.
    Chinese Academy of Sciences, Beijing, China.
    Zhao, J.
    Tianjin University, Tianjin, China.
    Jin, G.
    Inner Mongolia University of Science and Technology, Baotou, 014010, China.
    Wu, W.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology (KTH), Stockholm, Sweden.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jin, H.
    Chinese Academy of Sciences, Beijing, China.
    Mobilized thermal energy storage: Materials, containers and economic evaluation2018Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 177, s. 315-329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The transportation of thermal energy is essential for users who are located far away from heat sources. The networks connecting them achieve the goal in efficient heat delivery and reasonable cost, especially for the users with large heat demands. However, it is difficult to satisfy the heat supply of the detached or emergent users with the existing pipelines. Therefore, a promising alternative, called mobilized thermal energy storage (M-TES), was proposed to deliver the heat flexibly without the restriction of networks. In this paper, a review of studies on M-TES is conducted in terms of materials, containers and economic evaluation. The potential candidates of materials, such as sugar alcohols, hydrated salts, alkalies and zeolite are reviewed and compared based on their thermophysical properties, price, advantages and disadvantages. Various containers, including the shell-and-tube, encapsulated, direct-contact, detachable and sorptive types, are discussed from the aspects of configuration, performance and utilization. Furthermore, the studies on the economic evaluation of M-TES systems are summarized and discussed based on the analysis of the economic indicators, including initial cost, operating cost, revenue, subsidy and energy cost. Finally, the challenges and future perspectives for developing M-TES are presented. © 2018 Elsevier Ltd

  • 168.
    Guo, S.
    et al.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Zhao, J.
    Tianjin University, Tianjin, China.
    Wang, W.
    Sun Yat-Sen University, Guangzhou, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology, Stockholm, Sweden.
    Jin, G.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Zhang, Z.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Gu, J.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Niu, Y.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Numerical study of the improvement of an indirect contact mobilized thermal energy storage container2016Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 161, s. 476-486Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the melting and solidification behaviours of the PCM in an indirect contact mobilized thermal energy storage (ICM-TES) container were numerically investigated to facilitate the further understanding of the phase change mechanism in the container. A 2D model was built based on the simplification and assumptions of experiments, which were validated by comparing the results of computations and measurements. Then, three options, i.e., a high thermal conductivity material (expanded graphite) addition, the tube diameter and the adjustment of the internal structure of the container and fin installation, were analyzed to seek effective approaches for the improvement of the ICM-TES performance. The results show that the optimal parameters of the three options are 10vol.% (expanded graphite proportion), 22mm (tube diameter) and 0.468m2 (fin area). When the three options are applied simultaneously, the charging time is reduced by approximately 74% and the discharging time by 67%.

  • 169.
    Guo, S.
    et al.
    MOE, Tianjin University, Tianjin, China.
    Zhao, J.
    MOE, Tianjin University, Tianjin, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology, Stockholm, Sweden.
    Jin, G.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Wang, X.
    Inner Mongolia University of Science and Technology, Baotou, China.
    Economic assessment of mobilized thermal energy storage for distributed users: A case study in China2016Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 88, s. 656-661Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mobilized thermal energy storage (M-TES) system can be an alternative of the conventional heating system to meet the heat demand for distributed users. This paper conducted a case study of the M-TES system in China. The operating strategies (OS) of the M-TES with different transportation schemes were compared. Moreover, the economic assessment was performed based on the project's net present value (NPV) and payback period (PBP). The OS with 6 trips per day is the most profitable with pay-back time of about 2, 3 and 5 years if the waste heat costs at the level of 0 €/MWh, 3300€/MWh, and 6600 €/MWh, respectively. 

  • 170.
    Guo, Shaopeng
    et al.
    Inner Mongolia Univ Sci & Technol, China.
    Zhao, Jun
    Tianjin Univ, China..
    Wang, Weilong
    Sun Yat Sen Univ, China..
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jin, Guang
    Inner Mongolia Univ Sci & Technol, China..
    Wang, Xiaotong
    Inner Mongolia Univ Sci & Technol, China..
    Techno-economic assessment of mobilized thermal energy storage for distributed users: A case study in China2017Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 194, s. 481-486Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mobilized thermal energy storage (M-TES) system is a promising alternative to conventional heating systems to meet the heat demand for distributed users. This paper provided a techno-economic assessment of the M-TES system based on a case study in China. According to the analysis of the design specifications of the heating system, the suitability of matching the M-TES with existing heating systems was analyzed. The results show that the M-TES is appropriate for use with heating systems with a fan-coil unit and under-floor pipe. Containers and operating strategies for the M-TES with different transportation schemes were also designed. The maximum allowed load of the M-TES container is 39 t according to the discussion of transportation regulations on the road. The cost and income of the M-TES in the study case were estimated, and the net present value (NPV) and payback period (PBP) were also calculated. The best operating strategy is the use of 2 containers and 4 cycles of container transportation per day, with a PBP of approximately 10 years. The M-TES is applicable for middle and small-scale heat users in China. (C) 2016 Elsevier Ltd. All rights reserved.

  • 171.
    Gustafsson, M.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Swing Gustafsson, Moa
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Myhren, J. A.
    Dalarna University, Falun, Sweden.
    Bales, C.
    Dalarna University, Falun, Sweden.
    Holmberg, S.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Techno-economic analysis of energy renovation measures for a district heated multi-family house2016Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 177, s. 108-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Renovation of existing buildings is important in the work toward increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO2 emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump.Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO2 emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact. 

  • 172.
    Gyllhag, Jacob
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Energieffektivisering i verkstadsindustri: Tillämpning hos LEAX Mekaniska AB i Köping2011Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Energieffektivisering är en av möjligheterna att överväga för att nå ett medvetet, hållbart och modernt samhälle. Begreppet är sedan länge myntat inom sektorerna bostäder och kontor, men har inte riktigt nått lika långt inom industrisektorn än; även om potentialen för effektivisering är minst lika vanligt förekommande där.

    LEAX Mekaniska AB i Köping, som är ett verkstadsindustriföretag specialinriktat på fordonskomponenter till den tunga fordonsindustrin, har förstått potentialen som finns tillgänglig när det gäller effektivare energianvändning. Efter att tidigare ha utfört lättare mätningar och beräkningar själva så har de nu valt att initierat ett examensarbete som har som syfte att utreda möjligheten att återvinna spillvärme från de egna processerna, och att via en värmepumpanläggning uppgradera värmen så att den kan utnyttjas för uppvärmning av de egna lokalerna istället. I dagsläget kyls spillvärmen bort via en kylvattenkrets kopplad till ett kyltorn på taket.

    I aktuell rapport presenteras först teorier och metoder kring energieffektivisering och energiåtervinning. Sedan presenteras grunderna om termiska processer och värmepumpanläggningar. Slutligen presenteras själva tillämpningen hos LEAX Mekaniska AB.

    Utredningen visar att den potentiella effekten som kan utnyttjas till förångning i en värmepumpanläggning istället för att kylas bort på taket är i storleksordningen 170 kW. Med en kompressordriven värmepump bör effekten gå att uppgradera till närmare 230 kW enligt beräkningar utförda i datorprogrammet CoolPack. Den uppskattade investeringen för installationen och besparingen den åstadkommer beräknas sedan, och återbetalningstiden för investeringen beräknas. I och med den aktuella utredningen så blir återbetalningstiden cirka 4 år och 9 månader (4,77 år).

  • 173.
    Haifang, Lyu
    et al.
    Academy of Chinese Energy Strategy, China University of Petroleum, Beijing, Ch.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Academy of Chinese Energy Strategy, China University of Petroleum, Beijing, Ch.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bin, Xv
    Academy of Chinese Energy Strategy, China University of Petroleum, Beijing, Ch.
    Research on Chinese Solar Photovoltaic Development Based on Green-trading Mechanisms in Power System by Using a System Dynamics Model2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 3960-3965Artikel i tidskrift (Refereegranskat)
  • 174.
    Hallstrom, Olof
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Fueldner, Gerrit
    Fraunhofer Inst Solare Energiesyst ISE, Freiburg, Germany.
    Integration of sorption modules in Sydney type vacuum tube collector with air as heat transfer fluid2015Ingår i: INTERNATIONAL CONFERENCE ON SOLAR HEATING AND COOLING FOR BUILDINGS AND INDUSTRY, SHC 2014, 2015, Vol. 70, s. 445-453Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reduced thermal losses and simplified system integration have previously been identified as main opportunities to improve the concept of collector integrated sorption modules for solar heating and cooling. A concept for a facade integrated sorption collector using Sydney type vacuum tube technology and air based heat transfer has been developed and tested in the laboratory. The results from the tests have been used to validate an existing TRNSYS model that has been modified for use with air as heat transfer fluid. The work has been conducted within the FP7 EU iNSPiRe project with the aim to develop a plug & play solar cooling and heating solution. (C) 2015 The Authors. Published by Elsevier Ltd.

  • 175.
    Hallström, Olof
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Design Optimization of a Sorption Integrated Sydney Type Vacuum Tube Collector2017Ingår i: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 139, nr 2, artikel-id 021007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to reach the targets on emissions set by the European Commission, both new and existing buildings must reduce their fossil fuel inputs. Solar thermal cooling supplying on-site renewable heating and cooling could potentially contribute toward this goal. In this paper, a novel concept for solar thermal cooling providing efficient coproduction of cooling and heating based on sorption integrated vacuum tube collectors is proposed. A prototype collector has been constructed and tested in a solar laboratory based on a method developed specifically for sorption integrated collectors. From the test results, the key performance parameters have been determined and used to calibrate a mathematical model for trnsys environment. System simulation has been conducted to optimize the collector and sorption module configuration by performing a parametric study where different vacuum tube center-center (C-C) distances and sorption module designs are tested for a generic hotel in Ankara, Turkey. The parametric study showed that the heating and cooling output per year can be as high as 1000 kWh/m2 for solar fractions above 50%, and that the output per sorption module compared to the prototype can more than double with an optimized design. Furthermore, cooling conversion efficiencies defined as total cooling output per total solar insolation can be as high as 26% while simultaneously converting 35-40% of the incident solar energy into useful hot water.

  • 176.
    Hansen, Rickard
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Estimating the amount of water required to extinguish wildfires under different conditions and in various fuel types2012Ingår i: International journal of wildland fire, ISSN 1049-8001, E-ISSN 1448-5516, Vol. 21, nr 5, s. 525-536Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In wildland fires where water is used as the primary extinguishing agent, one of the issues of wildfire suppression is estimating how much water is required to extinguish a certain section of the fire. In order to use easily distinguished and available indicators, the flame length and the area of the active combustion zone were chosen as suitable for the modelling of extinguishing requirements. Using Byram's and Thomas' equations, the heat release rate per unit length of fire front was calculated for low-intensity surface fires, fires with higher wind conditions, fires in steep terrain and high-intensity crown fires. Based on the heat release rate per unit length of fire front, the critical water flow rate was calculated for the various cases. Further, the required amount of water for a specific active combustion zone area was calculated for various fuel models. Finally, the results for low-intensity surface fires were validated against fire experiments. The calculated volumes of water can be used both during the preparatory planning for incidents as well as during firefighting operations.

  • 177.
    Hansen, Rickard
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Investigation on fire causes and fire behaviour: Vehicle fires in underground mines in Sweden 1988–20102013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report is part of the research project “Fire spread and heat release rate of underground mining and tunnelling vehicles – BARBARA”, conducted by a research group at MälardalenUniversity.

    The project’s aim is to improve fire safety in mines and tunnels during construction in order to obtain a safer working environment for the people working for the mining companies as well as the tunnelling companies in Sweden or for visitors in mines open to the public.

    This report deals with the second step in the project: the investigation regarding fire causes and fire behaviour of vehicle fires in underground mines based upon material from GRAMKO (the work environment committee of the mine and mineral industry in Sweden).

    The main purposes of the investigation are:

    • To investigate and present fire causes, types of vehicles involved in fires, fire spread and fire behaviour of vehicle fires in underground mines.
    • To give recommendations on the continued work with the full-scale fire tests regarding the initial fire and its position.

    The conclusions were that:

    • With respect to vehicle fires involving only the start object, a typical fire occurs in a loader or a drilling rig and is due to electrical fault – for example short-circuit of cables – in the engine compartment, resulting in a slow and limited fire spread.
    • Regarding vehicle fires limited to the start object and an adjacent object is that it usually occurs in a loader and is due to electrical causes, resulting in a slow and limited fire spread. Typically, electrical cables would play an important role when it comes to the fire spread to adjacent objects.
    • Vehicle fires involving the entire vehicle usually occur in a service vehicle or a loader and are typically caused by diesel being sprayed – for example due to a pipe/hose coming loose – on the engine, resulting in a rapid fire spread.
    • In future full-scale fire experiments involving a diesel loader and a drilling rig, the vehicles will have to be ignited using a diesel fire – for example a pool fire under­neath or inside the engine compartment – that is shielded and positioned close to larger amounts of combustibles – such as tires or hydraulic hoses – and continuously distributed fuels – such as electrical cables – in order to achieve a rapid fire growth and fire spread that eventually engulf the entire vehicle. 
  • 178.
    Hansen, Rickard
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Methodologies for calculating the overall heat release rateof a vehicle in an underground structure2012Ingår i: Proceedings from the fifth international symposium on tunnel safety and security", New York, USA, March 14-16, 2012 / [ed] Anders Lönnermark & Haukur Ingason, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Most common type of object involved in fires in underground structures such as underground minesare vehicles [1-3]. A major concern is the lack of documented fire experiments in vehicles/mobileequipment, which is especially the case for working vehicles such as loaders, drilling rigs etc. Theresulting heat release rate (HRR) curves are essential knowledge when designing new tunnel or minesections and overlooking existing sections, thus there is a great need for HRR curves.This paper encompasses the measurement of the HRR for two full-scale fire experiments with vehiclesrepresentative for underground structures and the reconstruction of the measured HRR by investigatingwhat methodology that fits the measured values best. The main purpose of the methodologies is toprovide HRR curves without having to perform full-scale fire tests of the vehicles, which would be ofconsiderable value.

  • 179.
    Hansen, Rickard
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Regression analysis of wildfire suppression2012Ingår i: Proceedings from the third international conference on modelling, monitoring and management of forest fires", New Forest, United Kingdom, May 22-24, 2012 / [ed] Brebbia C.A. & Perona G., 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the most important aims of forest fire research is how to better controlforest fires. One way to attain this aim is to develop better decision tools forestimating how much water is required for extinguishing a fire with a specific setof conditions. There has in the past generally been little research conducted withrespect to water requirements when suppressing a wildfire. A number ofexperiments were conducted in the early ‘70s where a spray rig with a nozzlearrangement was used in order to apply water uniformly across a fuel bed. Twostudies regarding the required duration of water application related to fires inbuildings were conducted in the past. Both studies were based upon statisticaldata from fire brigades; the duration of water application was determined as afunction of the fire area. This paper encompasses an analysis of more than64,000 wildfires occurring in Sweden between 1996 and 2009. The valuescalculated from the obtained formulations with regression analysis were found tobe in good agreement in the following cases: The amount of water as a functionof the extinguishing time, the extinguishing time as a function of the fire area;and the fire area as a function of the flame height. It was observed that thederived equations from the analysis in the above cases could provide an accuratecomputation. These relationships could be of considerable use when developingdecision tools for wildfire suppression, optimizing the use of resources duringthe suppression activities.

  • 180.
    Hansen, Rickard
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Smoke spread calculations for fires in underground mines2010Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report is part of the research project “Concept for fire and smoke spread prevention in mines”, conducted by a research group at Mälardalen University.The project is aimed at improving fire safety in mines in order to obtain a safer working environment for the people working for the mining companies in Sweden or for visitors in mines open to the public.This report deals with the issue on smoke spread calculations for fires in underground mines.The main purposes of the report are:- Using both one- or two-dimensional calculation models as well as three-dimensional CFD calculation models.- Positioning the design fires (a pool fire, a fire in a loader, a fire in a loader in a sprinklered drift, a cable fire and a bus fire) at various sites with respect to for example the ventilation system.- Investigating the complexities of the various models, their limitations and deficiencies etc.- Comparing the results from the calculation models with each other and with experimental data where applicable and available.The work in this report started with describing smoke spread in underground mines in general and then continuing with describing three types of calculation models used in this report. After that calculations and simulations were conducted – using the three models – for the five designated design fire scenarios and the results were presented for strategic sites with respect to egress safety and the intervention of the fire and rescue services. The results from the CFD simulations were thereafter validated with respect to flame temperature and grid size convergence. It is misleading to fully compare the outputs of the three calculation models with each other without considering the differences and limitations of the three models as they are based upon different assumptions that differ considerably. For example the hand calculation expressions and the mine ventilation network simulation program assume unidirectional flow in the drifts compared with FDS that account for multi directional flows in the drifts. Also the hand calculation expressions and the mine ventilation network simulation program both assume complete mixture of air and fire gases while FDS does not make that assumption. Visibility is not one of the output parameters of the mine ventilation network simulation program, thus limiting the available data for comparison. But one of the purposes of this report was to investigate the complexities, limitations and deficiencies of the involved models.The advantage of the one- and two-dimensional models is the fact that the computational requirements are considerably lower than compared with a CFD model. Also with Ventgraph it is possible to obtain fast and transient solutions even though the simulated system of mine drifts is vast and complex. The advantage of FDS is the fact that it will model the area closest to the fire most accurately of the three models, for example accounting for multi directional flows in the near area of the fire. The disadvantages of the models are for example that it is not possible to fully account for the highly variable heat release rate of for example a fire in a tyre or in a vehicle when using a mine ventilation network program, as the ramp up to the maximum heat release rate is assumed to be linear and that every fire in a branch is assumed to be constant after reaching the maximum heat release rate. This does not apply to heat release rate curves that are uniform in shape such as a pool fire; in this case the heat release rate values used will be practically the same in all three types of calculation models.Also the time periods of the simulations differ between the three models as the simulations in FDS will become impractically long as the time to simulate increases due to higher computational requirements. Thus only the first 10-20 minutes were simulated in FDS and so the chance of comparison in for example the case of the fire in the loader is strongly limited.When comparing the results of the three calculation models the following conclusions can be made:- The mine ventilation network simulation program generally shows higher temperatures at the measuring points compared with the outputs of the other two models. One probable reason for this is that the heat release rate could not be represented as adequately as for the other two models; in all cases the heat release rate levels were higher for the mine ventilation network simulation program.- Generally the hand calculations showed much lower visibility figures than the CFDmodel. One reason for this – besides the fact that we are dealing with two models withvastly different approaches - is most likely in the difference in the types of smokecharacteristic factors used in the two types of models.- The FDS simulations generally showed small changes in temperature when comparingwith the other two models. This could be attributed to the fact that the measuring pointsare positioned at fairly large distances from the fire and thus the fire gases will coolconsiderably. Also the maximum heat release rate of some of the fires was small - ~1MW – and thus the impact on the nearby environment will be limited.- The results of the hand calculations with respect to the visibility is a good approximationfor the design fires with fairly low maximum heat release rate as the stratification in thiscase will be almost nonexistent and thus the smoke spread can be assumed to be equal tothe ventilation velocity in a drift (one dimensional smoke spread).- With respect to the egress safety the visibility will be the critical factor. In the case of thepool fire (design fire) the visibility will start to decrease at an early stage of the fire bothaccording to the hand calculations and the FDS simulation. After approximately a fewminutes the visibility in a large section of the connecting main ramp will be affected dueto the open nature of the area. Thus the egress will have to take place at an early stage inorder to ensure safety. Regarding the fire in the loader, the fire in the parking drift andthe cable fire the hand calculations indicate a sharp decline in visibility after a fewminutes, but the facts that the FDS simulation showed no differences in visibility and thatthe heat release rate is relatively small in all three cases (<1 MW) would indicate that thevisibility would be affected but in a limited manner and thus the egress safety will not belargely affected during the first 10-20 minutes due to for example the large spaces in themine drifts. With respect to the bus fire the same conclusions are drawn as in the case ofthe pool fire except that the FDS simulation predicts a much slower smoke spread thanthe results from the hand calculations.- With respect to the intervention from the fire and rescue services the visibility will also bethe critical factor as for the egress safety. The loader fire in the sprinklered drift and thecable fire should generally not pose any large problem to the intervention of the fire andrescue service, as the maximum heat release is small and the smoke spread largely limited.But the pool fire, the loader fire and the bus fire will be problematic to the interventionof the fire and rescue service as the maximum heat release is large and the smoke spreadis extensive affecting a large area before the arrival of the fire and rescue service (>30minutes). Thus the fire and rescue service will have to start the intervention at a largedistance from the site of the fire and work its way towards the fire. This will take a longtime and will decrease the chance of rescuing any personnel left in the area.As no data from conducted full-scale fire experiments were found that were applicable to any ofthe five design fire scenarios, future work should deal with validating the results of the threemodels with experimental results from conducted full scale fire tests corresponding to any of thefive design fire scenarios. In this case more profound comparisons and conclusions can bedrawn. The work and reflections from this report can be used when working on the full-scale fireexperiment.Measuring points should be placed in the near vicinity to the fire as well as sites further awayfrom the fire (> 50 m), this in order to effectively investigate and compare the results of one- andtwo-dimensional models versus a three dimensional model.Also further and deeper studies of the applied mine ventilation network simulation programshould be performed, investigating for example the assumptions and calculation models behindthe specific software.

  • 181.
    Hansen, Rickard
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Ingason, Haukur
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Full-scale fire experiments with mining vehicles in an underground mine2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report comprises two full scale fire experiments in a mine drift in Sala, Sweden,involving a loader and a drilling rig respectively.

    It was found in the experiment involving the loader that the front part of the vehiclenever ignited. The maximum measured heat fluxes at the front tyres were found tonever exceed the critical heat flux of natural rubber and thus ignition never occurred.Furthermore, the maximum temperature recorded at the hydraulic hoses in the waistwas 381 K, thus the low temperatures did not allow for further fire spread. The maximumheat release rate from the experiment was 15.9 MW and it was attained approximately 11 minutes after ignition. The resulting heat release rate curve of the wheel loaderfire displays a fire that is dominated by initially the sudden increase when primarily the first tyre is engulfed by flames and then by the slowly declining heat release ratesof the large tyres of the vehicle. Still, the stop of fire spread from the waist and forward clearly shortened the duration of the fire considerably.

    It was found in the experiment with the drilling rig that the entire vehicle had participated in the fire and the combustible material had been consumed – except for the hydraulic hoses approximately two meters in front of the cab and forward, some amount of hydraulic oil and most of the low voltage cable on the cable reel. The maximum heatrelease rate from the experiment was 29.4 MW and it was attained after 21 minutes. The resulting heat release rate curve of the drilling rig displays a fire with high heat release rates and relatively short lived.

  • 182.
    Hansen, Rickard
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Ingason, Haukur
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Heat release rate measurements of burning mining vehicles in an underground mine2013Ingår i: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 61, s. 12-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Heat release rates from two full-scale fire experiments with mining vehicles in an underground mine are presented. The mining vehicles involved were a wheel loader and a drilling rig typical for mining operations. The calculated peak heat release rate of the loader was 15.9 MW and occurred after approximately 11 min from ignition. The calculated peak heat release rate of the drilling rig was 29.4 MW and occurred after approximately 21 min from ignition. The heat release rate was calculated from measured data of gas concentrations of oxygen, carbon monoxide and carbon dioxide, measured gas velocity and measured gas temperatures. The fuel load of the wheel loader consisted mainly of the tyres, the hydraulic oil and the diesel fuel. The fuel load of the drilling rig consisted mainly of the hydraulic oil and the hydraulic hoses. The calculated heat release rate curves were controlled by comparing the summed up energy contents of the participating components with the integrated heat release rate curves. © 2013 Elsevier Ltd.

  • 183.
    Hao, Y.
    et al.
    Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China.
    Li, W.
    Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China.
    Tian, Z.
    Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China.
    Jin, H.
    Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Integration of concentrating PVs in anaerobic digestion for biomethane production2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, ISSN 0306-2619, Vol. 231, s. 80-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biogas produced from anaerobic digestion processes is considered as an important alternative to natural gas and plays a key role in the emerging market for renewable energy. Aiming at achieving a more sustainable and efficient biomethane production, this work proposed a novel energy system, which integrates concentrating photovoltaic/thermal (C-PV/T) hybrid modules into a biogas plant with chemical absorption for biogas upgrading. The investigated energy system was optimized based on the data from an existing biogas plant, and its techno-economic feasibility was evaluated. Results show that about 7% of the heat consumption and 12% of the electricity consumption of the biogas plant can be covered by solar energy, by using the produced heat in a cascade way according to the operating temperature of different processes. The production of biomethane can also be improved by 25,800 N m3/yr (or 1.7%). The net present value of the integrated system is about 2.78 MSEK and the payback period is around 10 years. In order to further improve the economic performance, it is of great importance to lower the capital cost of the C-PV/T module. 

  • 184.
    Hedlund, Philip
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Detection of glass in RDF using NIR spectroscopy2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Purpose of this study was to investigate the possibilities of using Near-infrared (NIR) spectroscopy to detect glass in refuse derived fuel (RDF) as well as what on-line data of glass content could be used for in terms of boiler operation and performance determination. Sample configurations were done with dried RDF (to prevent mass loss due to moisture and spectroscopic disturbance) and increasing concentrations of colored soda-lime glass, total of 100 samples. Glass was randomly scattered among the RDF by shaking the added glass and RDF in a bucket to generate representative samples of real life conditions. NIR-spectra acquisition was done between 12000 and 4000 cm-1, at 8 cm-1 resolution and average of 32 scans. The determination of boiler performance was done in accordance to Swedish standards for acceptance testing and heat loss due to glass was treated as slag. Resulting performance calculations showed boiler efficiency via indirect method matching efficiency calculated via direct method (deviating at maximum 2 %) which validates the summarized losses (including due to glass). The heat loss due to glass was calculated to 0,068 MW/%glass, which equated to average of 0,16 MW for 2,37 % glass. Total heat loss was amounted to an average of 11,53 MW. The developed models were not satisfactory in their quality of regression prediction. Although some had, through pre-processing, good development of explained variance at increasing factors, but still had a “Not Applicable” coefficient of determination by regression prediction. The poor quality of models can be explained by poor glass detection (poor representation) of the spectroscopic instrument due to a combination of glass being randomly scattered in the background material and sometimes covered by RDF as well as that the NIR-spectroscopy light beam only hits a small area. By increasing the number of samples upwards 300 -500, the effect of random scatter of glass can be mitigated and acceptable models could be acquired.

  • 185.
    Hennessy, Jay
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. RISE Research Institutes of Sweden, Borås, Sweden.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Towards smart thermal grids: Techno-economic feasibility of commercial heat-to-power technologies for district heating2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 228, s. 766-776Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent improvements in low-temperature heat-to-power (LTHtP) technologies have led to an increase in efficiency at lower temperatures and lower cost. LTHtP has so far not been used in district heating. The aim of the study is to establish under what conditions the use of existing LTHtP technology is technically and economically feasible using a district heating system as the heat source. The organic Rankine cycle (ORC) is identified as the most interesting LTHtP technology, due to its high relative efficiency and the commercial availability of devices operating at temperatures in the district heating operating range. The levelised cost of electricity of several ORC devices is calculated for temperatures found in district heating, assuming a zero cost of heat. A case study from Sweden is used to calculate the levelised cost of electricity, the net present value and payback period, based on income from the electricity produced, excluding taxes. Hourly spot market electricity prices from 2017 are used, as well as forecast scenarios for 2020, 2030 and 2040. A sensitivity study tests the importance of electricity price, cost of heat and capital/installation cost. Based on the case study, the best levelised cost of electricity achieved was 26.5 EUR/MWh, with a payback period greater than 30 years. Under current Swedish market conditions, the ORC does not appear to be economically feasible for use in district heating, but the net present value and payback period may be significantly more attractive under other countries’ market conditions or with reduced capital costs. For a positive net present value in the Swedish market the capital cost should be reduced to 1.7 EUR/W installed, or the average electricity price should be at least 35.2 EUR/MWh, if the cost of heat is zero. The cost of heat is an important factor in these calculations and should be developed further in future work.

  • 186.
    Hermansson, K.
    et al.
    Sigholm Konsult, Västerås, Sweden.
    Kos, C.
    Flowocean AB, Västerås, Sweden.
    Starfelt, F.
    Vattenfall AB, Uppsala, Sweden.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB Corporate Research, Västerås, Sweden.
    Zimmerman, Nathan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    An Automated Approach to Building and Simulating Dynamic District Heating Networks2018Ingår i: IFAC-PapersOnLine, ISSN 2405-8963, Vol. 51, nr 2, s. 855-860Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Nordic countries, district heating accounts for a large share of the consumers’  heat demand. In Sweden, roughly 50% of the total heat demand is attributed to district heating. Which, over the past few years, is equivalent to around 50 TWh, and imposes a difficult balance between supply and demand for the suppliers of district heating. For large networks the propagation of heat from supplier to end-user can vary several hours. Further complexities of large networks, which can consist of multiple overlapping rings, is that during transient conditions the flow can actually change direction. A dynamic modeling library has been developed in Modelica using OpenModelica for district heating networks. Methods for modeling, handling data, simulating and the visualization of results has been developed using Matlab. The model has been validated using data from Mälarenergi  AB, a local provider of district heating in Västerås, Sweden. The model provides to an acceptable degree in predicting the heat propagation and temperature distribution in a localized case study. Adding a higher level of robustness, the model has the capacity to handle bi-directional and reversing flows in complex ring structures. Through this work, the combination of OpenModelica and Matlab, a framework for automating the building and simulation of district heating networks is obtainable. The implications of automating network modeling from computer-aided design drawings allows for a quick robust overview of how the network is working and how prospective additions to the network could impact the end-users. Furthermore, incorporating visual aspects for heat propagation in a network contributes to a higher understanding of complex network structures. 

  • 187.
    Holmberg, Aksel
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Pettersson, Oscar
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    DESIGN OF A TECHNO-ECONOMIC OPTIMIZATION TOOL FOR SOLAR HOME SYSTEMS IN NAMIBIA2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The expansion of the electrical grid and infrastructure is an essential part of development since it contributes to improved standard of living among the population. Solar home systems (SHS) are one solution to generate electricity for households where the national grid does not reach or is too sparsely populated to build a local mini-grid. Solar home system programs have been used as a solution for rural electrification in developing countries all over the world with various success, one of these countries is Namibia. A large fraction of the population in Namibia lacks access to electricity where most of the people live in rural areas not reached by the national electrical grid. However, several SHS clients in Namibia have been dissatisfied with their systems due to several issues regarding the service providers. Several service providers have limited technical know-how and therefore frequently over- and undersize system components and make mistakes during installations. An opportunity to improve SHS in Namibia is to develop a software tool that service provider can use to quickly calculate an optimum SHS in a user friendly way based on the electricity demands of the clients. An optimization model was developed using MS Excel which calculates the optimal SHS component capacities regarding cost and reliability with the use of Visual Basic macros. Various field studies and sensitivity analyses were conducted with the MS Excel model. The results were validated and compared with other software programs such as PVsyst and a Matlab model used in a previous study regarding solar power. Results show that several components in existing systems are incorrectly sized and that the MS Excel model could improve future installations and improve the reputation of SHS. The sensitivity analyses focused on cost, system reliability, system size and PV-module tilt and were implemented in the MS Excel model to optimize the results in a techno-economic perspective. The MS-Excel model was approved by Namibia Energy Institute and will be available for all service providers in Namibia.

  • 188.
    Hosain, Md Lokman
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Fluid Flow and Heat Transfer Simulations for Complex Industrial Applications: From Reynolds Averaged Navier-Stokes towards Smoothed Particle Hydrodynamics2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Optimal process control can significantly enhance energy efficiency of heating and cooling processes in many industries. Process control systems typically rely on measurements and so called grey or black box models that are based mainly on empirical correlations, in which the transient characteristics and their influence on the control parameters are often ignored. A robust and reliable numerical technique, to solve fluid flow and heat transfer problems, such as computational fluid dynamics (CFD), which is capable of providing a detailed understanding of the multiple underlying physical phenomena, is a necessity for optimization, decision support and diagnostics of complex industrial systems. The thesis focuses on performing high-fidelity CFD simulations of a wide range of industrial applications to highlight and understand the complex nonlinear coupling between the fluid flow and heat transfer. The industrial applications studied in this thesis include cooling and heating processes in a hot rolling steel plant, electric motors, heat exchangers and sloshing inside a ship carrying liquefied natural gas. The goal is to identify the difficulties and challenges to be met when simulating these applications using different CFD tools and methods and to discuss the strengths and limitations of the different tools.

    The mesh-based finite volume CFD solver ANSYS Fluent is employed to acquire detailed and accurate solutions of each application and to highlight challenges and limitations. The limitations of conventional mesh-based CFD tools are exposed when attempting to resolve the multiple space and time scales involved in large industrial processes. Therefore, a mesh-free particle method, smoothed particle hydrodynamics (SPH) is identified in this thesis as an alternative to overcome some of the observed limitations of the mesh-based solvers. SPH is introduced to simulate some of the selected cases to understand the challenges and highlight the limitations. The thesis also contributes to the development of SPH by implementing the energy equation into an open-source SPH flow solver to solve thermal problems. The thesis highlights the current state of different CFD approaches towards complex industrial applications and discusses the future development possibilities.

    The overall observations, based on the industrial problems addressed in this thesis, can serve as decision tool for industries to select an appropriate numerical method or tool for solving problems within the presented context. The analysis and discussions also serve as a basis for further development and research to shed light on the use of CFD simulations for improved process control, optimization and diagnostics.

  • 189.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Air-Gap Heat Transfer in Rotating Electrical Machines: A Parametric Study2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, s. 4176-4181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    More than half of all electrical energy is consumed by motors and generators in an industrialized country. About 5-25% of this energy is lost and converted to heat. This heat produced by the losses has adverse effect on the lifetime and performance of a machine. A machine has to be operated at a given temperature to achieve maximum efficiency, therefore heat transfer study of machines is of special interest to rotating machines manufacturers. In this paper we investigate the heat transfer in the air-gap between the rotor and the stator of a simplified induction motor using Computational Fluid Dynamics. We consider three different air-gap widths and rotation speeds to explore the change in air-gap heat transfer when changing the air-gap width and the rotation speed. The simulated average heat transfer coefficients for all the models are in good agreement with the correlations from published literature. The Taylor-Couette vortical flow pattern is observed in the air-gap in our simulation results for the models with large air-gaps. The numerical results show that the presence of Taylor-Couette vortices in the air-gap enhance the heat transfer. The heat transfer coefficient increases with the increase in the rotation speed and decreases with the decrease in the air-gap width. 

  • 190.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kristian, Rönnberg
    ABB AB, Corporate Research, Sweden.
    Taylor-Couette flow and transient heat transfer inside the annulus air-gap of rotating electrical machines2017Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 207, s. 624-633Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Losses in an electric motor amount to between 4–24% of the total electrical power, and are converted to heat. The maximum hot spot temperature is one of the design constraints of thermal and electrical performance. Several studies have explored flow and thermal characteristics inside the air-gap between two concentric rotating cylinders such as those found in electric motors, however the transient flow and thermal effects still remain a challenge. This study uses Computational Fluid Dynamics to predict the thermal behaviour of a machine rotating at the kind of speed usually encountered in motors. The Reynolds Averaged Navier-Stokes model together with the realizable k-ε turbulence model are used to perform transient simulations. Velocity profiles and temperature distribution inside the air-gap are obtained and validated. The transient flow features and their impact on thermal performance are discussed. The numerical results show turbulent Taylor vortices inside the air-gap that lead to a periodic temperature distribution. When compared to correlations from published literature, the simulated average heat transfer coefficient at the rotor surface shows overall good agreement. The transient effects introduce local impacts like oscillations to the Taylor-Couette vortices. These flow oscillations result in oscillations of the hotspots. However, this transient oscillatory behaviour does not show any additional impact on the global thermal performance.

  • 191.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Simulation and validation of flow and heat transfer in an infinite mini-channel using Smoothed Particle Hydrodynamics2018Ingår i: Energy Procedia, Elsevier, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fluid flow and heat transfer in small channels have a wide range of engineering and medical applications. It has always been a topic of numerous theoretical, numerical and experimental studies. Several numerical methods have been used to simulate such flows. The most common approaches are the finite volume method (FVM) and the direct numerical simulation (DNS), which are numerically expensive to solve cases involving complex engineering problems. The main purpose of this work is to investigate the usability of the mesh-free particle based Smoothed Particle Hydrodynamics (SPH) method to simulate convective heat transfer. To validate our approach, as a starting point, we choose to solve a simple well-established problem which is the laminar flow and heat transfer through an infinitely long mini-channel. The solution obtained from SPH method has been compared to the solution from FVM method and analytical solution with good accuracy. The results presented in this paper show that SPH is capable to solve laminar forced convection heat transfer, however, turbulent flow cases need to be considered to be able to utilize the SPH method for engineering thermal applications.

  • 192.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Sweden.
    Domínguez, J. M.
    EPHYSLAB Environmental Physics Laboratory, Universidade de Vigo, Spain.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Smoothed particle hydrodynamics modeling of industrial processes involving heat transfer2019Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 252, artikel-id 113441Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Smoothed Particle Hydrodynamics (SPH) is a mesh-free particle method that has been widely used over the past decade to model complex flows. The method has mainly been used to investigate problems related to hydrodynamics and maritime engineering, in which heat transfer does not play a key role. In this article, the heat-conduction equation is implemented in the open-source code DualSPHysics, based on the SPH technique, and applied to different study cases, including conduction in still water in a cavity, laminar water flow between two infinite parallel plates and tube bank heat exchanger. The thermal solutions obtained from SPH are benchmarked with the solutions from Finite Volume Method (FVM) and validated using available analytical solutions. DualSPHysics results are in good agreement with FVM and analytical models, and demonstrate the potential of the meshless approach for industrial applications involving heat transfer.

  • 193.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Domínguez, José
    University of VIGO, Spain.
    Crespo, Alejandro
    University of VIGO, Spain.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Smoothed Particle Hydrodynamics modeling of transient conduction and convection heat transferManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Smoothed Particle Hydrodynamics (SPH) is a mesh-free particle method that has been widely used in the last years to model some complex flows. SPH was mainly used to investigate problems related to hydrodynamics and maritime engineering where heat transfer is of no importance. Thermal problems have seldom been addressed due to the limitation of the main commercial and open-source SPH codes.

    In this article, the energy equation is implemented in the SPH based open-source code DualSPHysics to solve conduction and forced convection heat transfer problems. Laminar flow cases are simulated as the first validation cases of the implemented model. The studied cases include conduction in an aluminum block, conduction in still water in a cavity, laminar water flow between two infinite parallel plates and tube bank heat exchanger. The thermal solutions obtained from SPH are benchmarked with the solutions from Finite Volume Method (FVM) and also validated using available analytical solutions. The obtained results are in good agreement with FVM and available analytical models, which combined with the advantages of the meshless approach, show the high potential for industrial heat transfer applications.

    This development is an important step towards thermal optimization of several industrial applications that can’t benefit from the conventional FVM approach due to geometry or process complexities. The demonstrated SPH simulation and visualization capabilities contribute to build the future reliable energy-saving solutions.

  • 194.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB Corp Res, Sweden.
    Fdhila, Rebei Bel
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB Corp Res, Sweden.
    Literature Review of accelerated CFD Simulation Methods towards Online Application2015Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, s. 3307-3314Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Engineering advanced methods for example Computational Fluid Dynamics (CFD) are heavily used to solve, design and model complex industrial applications. They provide high accuracy however, the simulation time is too long and this limit its generalized use dramatically as for control purposes. CFD tools and methods are often used to analyze the energy distribution and management in different industrial processes like hot rolling industries, furnaces and boilers as well as a number of areas where mixing and thermal management are of importance. Huge amounts of energy are often fed into such processes. A small amount of optimization can provide a very large energy saving. It is now an urgent need to have a tool like real-time CFD to analyze, control and optimize on-line various industrial processes. This tool or method can contribute to build efficient and sustainable energy systems. The scope of this work is to find alternative simulation techniques that can also address industrial applications and provide solutions within a decent accuracy and resolution. In this paper we provide a literature review of those methods that can be categorized as mesh based, mesh free and hybrid that are capable of providing appropriate results in some key areas of interest. As a next step one of these methods will be implemented and coupled to CFD simulation of cooling impinging jets used to control the heat transfer and temperature behavior of a hot flat surface in a hot rolling process where thermal energy and cooling water are used with excess. (C) 2015 The Authors. Published by Elsevier Ltd.

  • 195.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Rönnberg, Kristian
    ABB AB, Corporate Research.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Air Flow inside Rotating Electrical Machines: A Comparison between Finite Volume and SPH Method2017Ingår i: Conference Proceedings of NAFEMS World Congress 2017 (NWC17), 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    A general, sufficiently accurate, applicable and reasonably fast approach to thermal analysis of rotating electrical machines is of high interest for motor and generator developers and manufacturers. The thermal performance and the lifetime of a machine is limited by the temperature distribution and the hot spot temperature. The most commonly encountered cooling medium is air and the temperature distribution is driven by the air flow pattern inside the machine. Two different Computational Fluid Dynamics methods, the mesh based Finite Volume Method (FVM) and the mesh free particle based Smoothed Particle Hydrodynamics (SPH) method are employed in this paper to model the airflow inside a rotating machine. Mesh based methods are quite robust, however, they are very expensive in terms of meshing effort and CPU time to be used extensively in R&D. Analysing and optimizing products with complex geometrical shapes need mesh generation for every specific design change and this may be the major part of the modelling process. This challenging task is not necessary for the SPH method. SPH method can also provide high quality 3D visualization that can improve the design process.

    This work investigates the usability of the SPH method when applied to rotating machinery for rotor speeds normally encountered in motors and generators. A comparison with an FVM based approach is also performed. Both the FVM and the SPH solvers show good agreement for the overall flow pattern inside the machine with some disagreement for the airflow inside the air-gap between the rotor and the stator. The FVM solver successfully captures the Taylor vortex flow inside the annulus air-gap which is in general a great modelling challenge. The SPH solver on the other hand shows great capability to couple rotation of the rotor and well represent the overall flow pattern inside the machine. However, the 3D SPH solver could not capture the complex Taylor vortices inside the air-gap which may be due to the limited number of particles used for the simulation. An increase in the number of particles would certainly improve the accuracy of the results as confirmed by the 2D SPH simulation. The present study shows that the SPH solver can be used to predict the air flow pattern inside rotating machines within an acceptable accuracy.

  • 196.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Sweden.
    Sand, U.
    ABB AB, Corporate Research, Sweden.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Sweden.
    Numerical Investigation of Liquid Sloshing in Carrier Ship Fuel Tanks2018Ingår i: IFAC-PapersOnLine, ISSN 2405-8963, Vol. 51, nr 2, s. 583-588Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Liquid sloshing inside a partially filled tank has a great impact on the fragile internal tank coating and also on the stability of carrier ships. Several studies highlighted the challenges encountered due to the sloshing and proposed anti-sloshing tank structures. However, sloshing of liquefied natural gas fuel in high pressure vessels during transportation still remain a challenge. In the present numerical study we consider a downscaled 2D geometry to investigate the sloshing. Non-dimensional numbers are used to downscale the geometry. The purpose is to understand the flow structures and validate the downscaling approach based on the similarity scale laws. In the present work, Computational Fluid Dynamics (CFD) based on the Reynolds Averaged Navier-Stokes equations (RANS) with the Volume of Fluid (VOF) method in one hand and the Smooth Particle Hydrodynamics (SPH) method in the other hand, are used to simulate the downscaled model. The results from both methods are compared and validated using experimental data. A full scale model have also been simulated using SPH to verify the applicability of the scaling laws. The SPH model shows the capability to efficiently capture the sloshing phenomena. The VOF and SPH provide similar results in terms of flow dynamics, pressure and forces. The overall numerical results agree with the measurements and show that SPH can be an efficient tool to be used in modelling sloshing phenomena, compared to the RANS-VOF approach which is expensive in terms of CPU time. However, features like turbulence need to be further investigated. 

  • 197.
    Hu, Y.
    et al.
    Cranfield University, Bedford, United Kingdom.
    Tewari, A.
    Cranfield University, Bedford, United Kingdom.
    Varga, L.
    Cranfield University, Bedford, United Kingdom.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology, Stockholm, Sweden.
    System dynamics of oxyfuel power plants with liquid oxygen energy storage2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, s. 3727-3733Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Traditional energy storage systems have a common feature: the generating of secondary energy (e.g. electricity) and regenerating of stored energy (e.g. gravitational potential, and mechanical energy) are separate rather than deeply integrated. Such systems have to tolerate the energy loss caused by the second conversion from primary energy to secondary energy. This paper is concerned with the system dynamics of oxyfuel power plants with liquid oxygen energy storage, which integrates the generation of secondary energy (electricity) and regeneration of stored energy into one process and therefore avoids the energy loss caused by the independent process of regeneration of stored energy. The liquid oxygen storage and the power load of the air separation unit are self-adaptively controlled based on current-day power demand, day-ahead electricity price and real-time oxygen storage information. Such an oxyfuel power plant cannot only bid in the day-ahead market with base load power but also has potential to provide peak load power through reducing the load of the air separation unit in peak time. By introducing reasoning rules with fuzzy control, the oxygen storage system has potential to be further extended by integrating renewable energy resources into the system to create a cryogenic energy storage hub. 

  • 198.
    Hu, Yukun
    et al.
    Royal Inst Technol.
    Li, Hailong
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Techno-economic evaluation of the evaporative gas turbine cycle with different CO(2) capture options2012Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 89, nr 1, s. 303-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The techno-economic evaluation of the evaporative gas turbine (EvGT) cycle with two different CO(2) capture options has been carried out. Three studied systems include a reference system: the EvGT system without CO(2) capture (System I), the EvGT system with chemical absorption capture (System II), and the EvGT system with oxyfuel combustion capture (System III). The cycle simulation results show that the system with chemical absorption has a higher electrical efficiency (41.6% of NG LHV) and a lower efficiency penalty caused by CO(2) capture (10.5% of NG LHV) compared with the system with oxyfuel combustion capture. Based on a gas turbine of 13.78 MW, the estimated costs of electricity are 46.1 $/MW h for System I. while 70.1 $/MW h and 74.1 $/MW h for Systems II and III, respectively. It shows that the cost of electricity increment of chemical absorption is 8.7% points lower than that of the option of oxyfuel combustion. In addition, the cost of CO(2) avoidance of System II which is 71.8 $/tonne CO(2) is also lower than that of System III, which is 73.2 $/tonne CO(2). The impacts of plant size have been analyzed as well. Results show that cost of CO(2) avoidance of System III may be less than that of System II when a plant size is larger than 60 MW.

  • 199.
    Hu, Yukun
    et al.
    Royal Inst Technol .
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Li, Hailong
    Effects of flue gas recycle on oxy-coal power generation system2012Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 97, nr SI, s. 255-263Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper examined and assessed various configuration options about emission removal including particles. SOx and NOx in an oxy-coal combustion system for CO2 capture. A performance analysis was conducted in order to understand the impacts of those options concerning process design, process operation and system efficiency. Results show that different flue gas recycle options have clear effects on the emissivity and absorptivity of radiating gases in boiler due to the change of flue gas compositions. The maximum difference amongst various options can be up to 15% and 20% for emissivity and absorptivity respectively. As a result, the heat transfer by radiation can vary about 20%. The recycle options also have impacts on the design of air heater and selective-catalytic-reduction (SCR) preheater. This is due to that the largely varied operating temperatures in different options may result in different required areas of heat exchangers. In addition, the dew point of flue gas and the boiler efficiency are affected by the configurations of flue gas recycle as well.

  • 200.
    Huang, C.
    et al.
    Tongji University, Shanghai, China.
    Li, Y.
    Tongji University, Shanghai, China.
    Li, X.
    Tongji University, Shanghai, China.
    Wang, H.
    Tongji University, Shanghai, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology (KTH), Sweden.
    Wang, X.
    Tongji University, Shanghai, China.
    Wu, J.
    Tongji University, Shanghai, China.
    Li, F.
    Tongji University, Shanghai, China.
    Understanding the water-energy nexus in urban water supply systems with city features2018Ingår i: Energy Procedia, Elsevier Ltd , 2018, s. 265-270Konferensbidrag (Refereegranskat)
    Abstract [en]

    The water-energy nexus has been introduced into urban water supply systems (WSSs) to improve the current plight of scarce resources and greenhouse effect in recent years. Urban water-energy integrated management is limited by the characteristics and reality of each city. In this paper, we characterize the comprehensive influence factors of energy use in China urban WSSs including geographic differences and city forms. The results indicate that the pressure of pipeline network and plain area ratio restricted by geomorphology would significantly impact the energy consumption during conveyance and distribution stage. For the city form aspect, the total volume of urban water supply and the leakage rate of pipeline networks play important roles in energy consumption of urban WSSs in China. In this study, the specific electricity consumption in WSSs was quantified, and several factors affected by city features which show strong correlation with energy use were determined. The results are of great significance to the energy saving in water supply systems in urban areas.

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