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  • 1.
    Li, Hailong
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Song, Jingjing
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sun, Q.
    Institute of Thermal Science and Technology, Shandong University, Jinan, China.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zhang, Q.
    China Petroleum University, Beijing, China.
    A dynamic price model based on levelized cost for district heating2019In: Energy, Ecology and Environment, ISSN 2363-7692, Vol. 4, no 1, p. 15-25Article in journal (Refereed)
    Abstract [en]

    District Heating (DH) is facing a tough competition in the market. In order to improve its competence, an effective way is to reform price models for DH. This work proposed a new dynamic price model based on the levelized cost of heat (LCOH) and the predicted hourly heat demand. A DH system in Sweden was used as a case study. Three methods were adopted to allocate the fuel cost to the variable costs of heat production, including (1) in proportion to the amount of heat and electricity generation; (2) in proportion to the exergy of generated heat and electricity; and (3) deducting the market price of electricity from the total cost. Results indicated that the LCOH-based pricie model can clearly reflect the production cost of heat. Through the comparison with other market-implemented price models, it was found that even though the market-implemented price models can, to certain extent, reflect the variations in heat demand, they cannot reflect the changes in production cost when different methods of heat production are involved. In addition, price model reforming can lead to a significant change in the expense of consumers and consequently, affect the selection of heating solution.

  • 2.
    Nian, V.
    et al.
    Energy Studies Institute, National University of Singapore, Singapore.
    Jindal, G.
    Energy Studies Institute, National University of Singapore, Singapore.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A feasibility study on integrating large-scale battery energy storage systems with combined cycle power generation – Setting the bottom line2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 185, p. 396-408Article in journal (Refereed)
    Abstract [en]

    Strong attention has been given to the costs and benefits of integrating battery energy storage systems (BESS) with intermittent renewable energy systems. What's neglected is the feasibility of integrating BESS into the existing fossil-dominated power generation system to achieve economic and environmental objectives. In response, a life cycle cost-benefit analysis method is introduced in this study taking into consideration three types of battery technologies, namely, vanadium redox flow battery, zinc bromine flow battery, and lithium-iron-phosphate battery. The objective is to evaluate the life cycle carbon emissions and cost of electricity production by combined cycle power generation with grid-connected BESS. Findings from the Singapore case study suggest a potential 3–5% reduction in the life cycle carbon emission factors which could translate to a cumulative carbon emission reduction of 9–16 million tonnes from 2018 to 2030 from electricity generation. Grid-connected BESS could reduce the levelized cost of electricity by 4–7%. A synergistic planning of CCGT and BESS could theoretically reduce the system level power generation capacity by 26% albeit a potential increase in the overall capital cost at the current cost of batteries. The projected battery cost reduction is critical in improving the feasibility of large-scale deployment. 

  • 3.
    Ahmed, Mobyen Uddin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Andersson, Peter
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Andersson, Tim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Aparicio, Elena Tomas
    Malardalen Univ, Future Energy Ctr, Sch Business Soc & Engn, SE-72123 Vasteras, Sweden.;Malarenergi AB, Sjohagsvagen 3, S-72103 Vasteras, Sweden..
    Baaz, Hampus
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Barua, Shaibal
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Bergström, Albert
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Bengtsson, Daniel
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Orisio, Daniele
    State Inst Higher Educ Guglielmo Marconi, Dalmine, Italy..
    Skvaril, Jan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zambrano, Jesus
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A Machine Learning Approach for Biomass Characterization2019In: INNOVATIVE SOLUTIONS FOR ENERGY TRANSITIONS / [ed] Yan, J Yang, HX Li, H Chen, X, ELSEVIER SCIENCE BV , 2019, p. 1279-1287Conference paper (Refereed)
    Abstract [en]

    The aim of this work is to apply and evaluate different chemometric approaches employing several machine learning techniques in order to characterize the moisture content in biomass from data obtained by Near Infrared (NIR) spectroscopy. The approaches include three main parts: a) data pre-processing, b) wavelength selection and c) development of a regression model enabling moisture content measurement. Standard Normal Variate (SNV), Multiplicative Scatter Correction and Savitzky-Golay first (SGi) and second (SG2) derivatives and its combinations were applied for data pre-processing. Genetic algorithm (GA) and iterative PLS (iPLS) were used for wavelength selection. Artificial Neural Network (ANN), Gaussian Process Regression (GPR), Support Vector Regression (SVR) and traditional Partial Least Squares (PLS) regression, were employed as machine learning regression methods. Results shows that SNV combined with SG1 first derivative performs the best in data pre-processing. The GA is the most effective methods for variable selection and GPR achieved a high accuracy in regression modeling while having low demands on computation time. Overall, the machine learning techniques demonstrate a great potential to be used in future NIR spectroscopy applications.

  • 4.
    Thyrel, M.
    et al.
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Aulin, Robert
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lestander, T. A.
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    A method for differentiating between exogenous and naturally embedded ash in bio-based feedstock by combining ED-XRF and NIR spectroscopy2019In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 122, p. 84-89Article in journal (Refereed)
    Abstract [en]

    Characterization of ash-generating elements is of great importance in bio-based processes using lignocellulosic biomass as feedstock. Spectral data using energy dispersive X-ray fluorescence (ED-XRF) spectroscopy and near-infrared (NIR) spectroscopy were recorded from 119 lignocellulosic samples collected at bio-based combined heat and power plants. These spectra were used in regression modeling by using orthogonal projections to lateral structures (OPLS) to predict ash mass fraction varying between 0.2 and 5.7% in the dry biomass. The ED-XRF models produced more robust calibrations with lower prediction errors than corresponding NIR models that underestimated ash mass fractions >2%, especially when extra samples contaminated with 0.2–4.3% exogenous ash to reach 5% ash mass fraction were validated using the constructed OPLS models. Thus, by combining these spectral techniques, it has been shown for the first time that it is possible to distinguish between naturally embedded bioash and ash originating from contamination in biomass samples. This opens up new routes and instrumentation development to monitor and control varying ash mass fractions better in bio-based feedstocks entering combustion processes or biorefinery processes. 

  • 5.
    Prabaharan, N.
    et al.
    School of Electrical and Electronics Engineering, SASTRA Deemed University, Thanjavur Tamil Nadu, India.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jerin, A.R.A.
    School of Electrical Engineering, Vellore Institute of Technology, Vellore Tamil Nadu, India.
    Palanisamy, K.
    School of Electrical Engineering, Vellore Institute of Technology, Vellore Tamil Nadu, India.
    A new approach for grid integration of solar photovoltaic system with maximum power point tracking using multi‐output converter2019Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new approach for grid integration of solar photovoltaic system using modified incremental conductance maximum power point tracking algorithm with multi-output converter and multilevel inverter. The multi-output converter is a combination of boost converter and switched capacitor function to generate different self-balanced output voltages using single switch, single inductor, 2N-1 diodes and 2N-1 capacitors. This topology is proposed to be used as DC link in applications where several controlled voltage levels are required with self-balancing and unidirectional current flow, such as photovoltaic (PV) or fuel cell generation systems with multilevel inverter. The utilization of multilevel inverter in the proposed system provides better quality of output voltage and current waveform thereby reducing the size of passive filters. Also, it eliminates the requirement of bulky transformers for grid integration. Multicarrier unipolar phase disposition pulse width modulation technique is employed for triggering the switches of the multilevel inverter. The proposed system is tested with standard test conditions using MATLAB/SIMULINK.

  • 6.
    Fentaye, Amare D.
    et al.
    Universiti Teknologi PETRONAS, Malaysia.
    Baheta, Aklilu T.
    Universiti Teknologi PETRONAS, Malaysia.
    Gilani, Syed I.
    Universiti Teknologi PETRONAS, Malaysia.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A Review on Gas Turbine Gas-Path Diagnostics: State-of-the-Art Methods, Challenges and Opportunities2019In: Aerospace, ISSN 2226-4310, Vol. 6, no 7, article id 83Article in journal (Refereed)
    Abstract [en]

    Gas-path diagnostics is an essential part of gas turbine (GT) condition-based maintenance (CBM). There exists extensive literature on GT gas-path diagnostics and a variety of methods have been introduced. The fundamental limitations of the conventional methods such as the inability to deal with the nonlinear engine behavior, measurement uncertainty, simultaneous faults, and the limited number of sensors available remain the driving force for exploring more advanced techniques. This review aims to provide a critical survey of the existing literature produced in the area over the past few decades. In the first section, the issue of GT degradation is addressed, aiming to identify the type of physical faults that degrade a gas turbine performance, which gas-path faults contribute more significantly to the overall performance loss, and which specific components often encounter these faults. A brief overview is then given about the inconsistencies in the literature on gas-path diagnostics followed by a discussion of the various challenges against successful gas-path diagnostics and the major desirable characteristics that an advanced fault diagnostic technique should ideally possess. At this point, the available fault diagnostic methods are thoroughly reviewed, and their strengths and weaknesses summarized. Artificial intelligence (AI) based and hybrid diagnostic methods have received a great deal of attention due to their promising potentials to address the above-mentioned limitations along with providing accurate diagnostic results. Moreover, the available validation techniques that system developers used in the past to evaluate the performance of their proposed diagnostic algorithms are discussed. Finally, concluding remarks and recommendations for further investigations are provided.

  • 7.
    Lu, H.
    et al.
    School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, China.
    Yu, X.
    School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tu, S. -T
    School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, China.
    Accurately measurement and efficiently recovery of ionic liquid in energy utilization of microalgae2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 1337-1341Conference paper (Refereed)
    Abstract [en]

    Chlorella vulgais, a kind of micro-alagae, is an attracting feedstock for bioenergy production, such as biodiesel and biogas. But its tough cell wall structure is the main obstacle to efficiently extracting lipids and other biomass. Ionic liquid (IL) can be used to hydrolyze its cell-wall. However, due to its high cost and toxicity, it is important to recover IL as much as possible. Therefore, a method that can accurately measure the content of ILs, is urgently needed. In this work, two common methods that are used to measure the content of ILs: equimolar titration method and ultraviolet absorbance spectra were compared. The results show that equimolar titration method is not available for trace quantity analysis of ionic liquids as the endpoint of titration is hard to be identified at low IL content (<10 mg/L); while UV absorbance spectra method can be used at low IL contents, whereas, it may result in big deviations. To further improve the accuracy of UV absorbance spectra method, concentrating the sample could be a potential solution.

  • 8.
    Jalilzadehazhari, Elaheh
    et al.
    Linnaeus University, Växjö, Sweden.
    Vadiee, Amir
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Johansson, Peter
    Jönköping University, Sweden.
    Achieving a trade‐off construction solution using BIM, an optimization algorithm, and a multi‐criteria decision‐making method2019In: Buildings, ISSN 2075-5309, E-ISSN 2075-5309, Vol. 9, no 4, p. 1-14, article id 81Article in journal (Refereed)
    Abstract [en]

    The Energy Performance of Building Directive obligated all European countries to reduce the energy requirements of buildings while simultaneously improving indoor environment quality. Any such improvements not only enhance the health of the occupants and their productivity, but also provide further economic benefits at the national level. Accomplishing this task requires a method that allows building professionals to resolve conflicts between visual and thermal comfort, energy demands, and life-cycle costs. To overcome these conflicts, this study exploits the incorporation of building information modelling (BIM), the design of experiments as an optimization algorithm, and the analytical hierarchy process (AHP) into a multi-criteria decision-making method. Any such incorporation can (i) create constructive communication between building professionals, such as architects, engineers, and energy experts; (ii) allow the analysis of the performance of multiple construction solutions with respect to visual and thermal comfort, energy demand, and life-cycle costs; and (iii) help to select a trade-off solution, thereby making a suitable decision. Three types of energy-efficient windows, and five types of ground floors, roofs, and external wall constructions were considered as optimization variables. The incorporation of several methods allowed the analysis of the performance of 375 construction solutions based on a combination of optimization variables, and helped to select a trade-off solution. The results showed the strength of incorporation for analyzing big-data through the intelligent use of BIM and a simulation in the field of the built environment, energy, and costs. However, when applying AHP, the results are strongly contingent on pairwise comparisons.

  • 9.
    Zimmerman, Nathan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindberg, Carl-Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB Force Measurement, Västerås, Sweden.
    Achieving lower district heating network temperatures using feed-forward MPC2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 15, article id 2465Article in journal (Refereed)
    Abstract [en]

    The focus of this work is to present the feasibility of lowering the supply and return temperatures of district heating networks in order to achieve energy savings through the implementation of feed-forward model predictive control. The current level of district heating technology dictates a need for higher supply temperatures, which is not the case when considering the future outlook. In part, this can be attributed to the fact that current networks are being controlled by operator experience and outdoor temperatures. The prospects of reducing network temperatures can be evaluated by developing a dynamic model of the process which can then be used for control purposes. Two scenarios are presented in this work, to not only evaluate a controller's performance in supplying lower network temperatures, but to also assess the boundaries of the return temperature. In Scenario 1, the historical load is used as a feed-forward signal to the controller, and in Scenario 2, a load prediction model is used as the feed-forward signal. The findings for both scenarios suggest that the new control approach can lead to a load reduction of 12.5% and 13.7% respectively for the heat being supplied to the network. With the inclusion of predictions with increased accuracy on end-user demand and feed-back, the return temperature values can be better sustained, and can lead to a decrease in supply temperatures and an increase in energy savings on the production side.

  • 10.
    Xi, X.
    et al.
    Academy of Chinese Energy Strategy, China University of Petroleum(Beijing), Beijing 102249, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yang, X.
    Academy of Chinese Energy Strategy, China University of Petroleum(Beijing), Beijing 102249, China.
    Yu, Z.
    Department of Energy and Petroleum Engineering, University of Stavanger, Stavanger 4036, Norway.
    Air pollution related externality of district heating - A case study of Changping, Beijing2019In: Energy Procedia, Elsevier Ltd , 2019, p. 4323-4330Conference paper (Refereed)
    Abstract [en]

    Air pollution, caused by the use of fossil fuel, has been an environmental plague in China. It has a strong negative impact on human health. Since the costs of damage to health are not born by the pollution producers, these costs translate to social externality. Policies have an important role in optimizing resource allocation, such as penalizing the pollutant producers and incentivizing clean energy development. Among others, replacing coal with natural gas for heating represents an important example of air quality improvement measures. This paper presents a study that evaluates the health impacts from air pollution and the external cost of the "Coal-To-Gas" policy in district heating using Changping District (Beijing, China) as an example. Four scenarios were considered based on the historical and standard PM2.5 concentration. Results show that PM2.5 is responsible for causing an increase of 40% premature deaths in 2015 and that the monetary value of damage to health is higher than 1.2 billion CNY. In 2016 and 2017, the reported air quality was better than that in 2015. As a result, 13.3% and 26% premature deaths caused by air pollution were avoided in 2016 and 2017 compared to 2015 respectively. If the PM2.5 concentration level were to be reduced to national standard, the number of premature deaths attributed to PM2.5 could further decrease to 47.7% compared to 2015. Overall, the Coal-To-Gas policy in district heating reduces 0.017%~0.45% of premature death caused by air pollution each year. Air pollution reduction policies, which are expected to improve air quality together in the future, and the specific policy of Coal-To-Gas in district heating, could make great contribution to reducing the premature death caused by environmental problem and need more attention from the government and the public.

  • 11.
    Maher, Azaza
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Eskilsson, Anton
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    An open-source visualization platform for energy flows mapping and enhanced decision making2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 3208-3214Conference paper (Refereed)
    Abstract [en]

    Visualization of energy consumption within the built environment, both in the private and public sectors, can be a potent tool for increasing conservation behavior. For instance, dynamics visualization could add new knowledge to the end-users to have a better understanding of the energy flows, dynamic mapping of the energy usage in order to avoid misplacing effort and resources, e.g. when it comes to selection of heating systems, investing in energy efficiency measures and renewables as well as when stakeholders are planning for new area to be populated with either commercial or residential buildings. This paper introduces an open-source visualization platform allowing various energy flows mapping in both time and space of a sports facilities. It further includes advanced functionalities such as key performance indicators and integrated prediction models to assist the benchmarking and decision making processes.

  • 12. Berkqvist, Julia
    et al.
    Johansson, Joakim
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Mälardalen University, School of Business, Society and Engineering, Industrial Economics and Organisation.
    Annie Lööf i svenska tidningsmedier - en diskursanalys2019In: Statsvetenskaplig Tidskrift, ISSN 0039-0747, no 2, p. 241-272Article in journal (Refereed)
  • 13.
    Yan, Jinyue
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH Royal Inst Technol, Dept Chem Engn, Stockholm, Sweden..
    Zhang, Z.
    Chongqing University, Chongqing, China.
    Carbon Capture, Utilization and Storage (CCUS)2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 235, p. 1289-1299Article in journal (Refereed)
  • 14.
    Du, Y.
    et al.
    College of Electronics and Information Engineering, Tongji University, Shanghai, China.
    Wang, C.
    College of Electronics and Information Engineering, Tongji University, Shanghai, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Song, Jingjing
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, B.
    School of Mechanical Engineering, Hubei University of Arts and Science, Hubei Province, China.
    Clustering heat users based on consumption data2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 3196-3201Conference paper (Refereed)
    Abstract [en]

    In today's district heating (DH) energy market, it is common to use user functional categories in price models to determine the heat price. However, users in the same category do not necessarily have the same energy consumption patterns, which potentially leads to unfair prices and many other practical issues. Taking into account heat usage characteristics, this work proposes two data-driven methods to cluster DH users to identify similar usage patterns, using practical energy consumption data. Efforts are focused on extracting representative features of users from their daily usage profiles and duration curves, respectively. Employing clustering based on these features, the resulting typical usage patterns and user category distributions are discussed. Our results can serve as potential inputs for future energy price models, demand-side management, and load reshaping strategies.

  • 15.
    Liu, Shengchun
    et al.
    Tianjin University of Commerce, China.
    Wu, Sicheng
    Tianjin University of Commerce, China.
    Hu, Yukun
    University College London, UK.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Comparative analysis of air and CO2 as working fluids for compressed and liquefied gas energy storage technologies2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. feb, p. 608-620Article in journal (Refereed)
    Abstract [en]

    With the large-scale use of intermittent renewable energy worldwide, such as wind energy and solar energy, energy storage systems are urgently needed and have been rapidly developed. Technologies of compressed gas energy storage (CGES) and liquefied gas energy storage (LGES) are playing an important role, and air has been commonly used as working fluid. CO2 is another potential working fluid and attracting more and more attention due to the rise of CO2 capture and utilization. However, it is still unclear which is the better working fluid. This paper comparatively analyzed the performance of CGES and LGES systems using air and CO2 as working fluids. Both diabatic and adiabatic CGES are considered. Simulation results show that except diabatic CGES systems, using CO2 could achieve a similar or even higher round-trip efficiency than using air. In addition, the use of CO2 instead of air as a working fluid has additional advantages, such as a lower storage temperature can be achieved at the same storage pressure for the adiabatic CGES system; and a higher condensing temperature can be achieved at the same condensing pressure for the LGES system, which can benefit the system design and operation.

  • 16.
    Lennermo, Gunnar
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Energianalys AB, Alingsås, Sweden.
    Lauenburg, P.
    Lund university, Sweden.
    Werner, S.
    Halmstad university, Sweden.
    Control of decentralised solar district heating2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 179, p. 307-315Article in journal (Refereed)
    Abstract [en]

    The purpose of decentralised solar district heating plants is to feed solar heat directly into district heating networks. This decentralised heat supply has to consider two major output conditions: a stable required feed-in supply temperature and a feed-in heat power equal to the heat output from the solar collectors. However, many installations cannot achieve the second output condition, since severe oscillations appear in the feed-in heat power. This problem can be solved by two different control concepts with either temperature- or flow-control. Detailed measurements from two reference plants are provided for these two different control concepts. One main conclusion is that a robust control system is characterized by the ability to provide required flows and temperatures. The major difference between robust and less robust control is that the supply temperatures and/or flows do not fluctuate even if the input conditions are unfavourable. 

  • 17.
    Song, C.
    et al.
    Tianjin University, 92 Weijin Road, Nankai District, Tianjin, China.
    Liu, Q.
    Tianjin University, 92 Weijin Road, Nankai District, Tianjin, China.
    Deng, S.
    Ministry of Education, Tianjin, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kitamura, Y.
    University of Tsukuba, Japan.
    Cryogenic-based CO2 capture technologies: State-of-the-art developments and current challenges2019In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 101, p. 265-278Article in journal (Refereed)
    Abstract [en]

    CO2 capture, utilization and storage has been recognized as a primary option to mitigate the issue of climate change caused by the utilization of fossil fuels. Several CO2 capture strategies have been developed, such as absorption, adsorption, membrane, chemical looping, hydrating and biofixation. Among different technologies, particular attention has been given to cryogenic CO2 capture by phase change. The aim of this study is to improve interest in cryogenic technologies for CO2 capture by providing an overview of the actual status of CCS. To reach this goal, the major strategies and technologies for CO2 capture from fossil fuel combustion have been reviewed. Simultaneously, the characteristics of cryogenic technologies for CO2 capture are summarized. The existing challenges that need to be overcome in cryogenic technology include cold energy sources, capture costs and impurities, etc. Finally, opportunities for the future development of cryogenic-based technologies are discussed. The results of this investigation indicated that cryogenic CO2 capture processes can be easily retrofitted to the existing industrial emission facilities and avoid the challenges associated with chemical solvents or physical sorbents. 

  • 18.
    Li, Yangyang
    et al.
    Tsinghua University.
    Jin, Yiying
    Tsinghua University.
    Borrion, Aiduan
    University College London.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Current status of food waste generation and management in China2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 273, p. 654-665Article in journal (Refereed)
  • 19.
    Lundström, Lukas
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Eskilstuna Kommunfastighet AB, Eskilstuna, Sweden.
    Akander, J.
    Division of Building, Energy and Environment Technology, Department of Technology and Environment, University of Gävle, Sweden.
    Zambrano, Jesus
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Development of a space heating model suitable for the automated model generation of existing multifamily buildings—a case study in Nordic climate2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 3, article id 485Article in journal (Refereed)
    Abstract [en]

    Building energy performance modeling is essential for energy planning, management, and efficiency. This paper presents a space heating model suitable for auto-generating baseline models of existing multifamily buildings. Required data and parameter input are kept within such a level of detail that baseline models can be auto-generated from, and calibrated by, publicly accessible data sources. The proposed modeling framework consists of a thermal network, a typical hydronic radiator heating system, a simulation procedure, and data handling procedures. The thermal network is a lumped and simplified version of the ISO 52016-1:2017 standard. The data handling consists of procedures to acquire and make use of satellite-based solar radiation data, meteorological reanalysis data (air temperature, ground temperature, wind, albedo, and thermal radiation), and pre-processing procedures of boundary conditions to account for impact from shading objects, window blinds, wind- and stack-driven air leakage, and variable exterior surface heat transfer coefficients. The proposed model was compared with simulations conducted with the detailed building energy simulation software IDA ICE. The results show that the proposed model is able to accurately reproduce hourly energy use for space heating, indoor temperature, and operative temperature patterns obtained from the IDA ICE simulations. Thus, the proposed model can be expected to be able to model space heating, provided by hydronic heating systems, of existing buildings to a similar degree of confidence as established simulation software. Compared to IDA ICE, the developed model required one-thousandth of computation time for a full-year simulation of building model consisting of a single thermal zone. The fast computation time enables the use of the developed model for computation time sensitive applications, such as Monte-Carlo-based calibration methods. 

  • 20.
    Tang, Y.
    et al.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Zhang, Q.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Y.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Liu, B.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Economic analysis on repurposed EV batteries in a distributed PV system under sharing business models2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 4304-4310Conference paper (Refereed)
    Abstract [en]

    In order to ensure the operation of distributed energy and relieve the pressure of retired EV batteries, repurposing EV batteries in energy storage for second-life use has gained increasing attentions. Considering that distributed battery storages are still not economically attractive at present, the booming of sharing economy may provide a more feasible option. Based on a non-cooperative game theoretical model, this study aims to make the economic analysis on repurposed EV batteries in a distributed PV system under sharing business models. Four scenarios were proposed, including: S1-without battery storage and without shared PV generation, S2-with battery storage and without shared PV generation, S3-with battery storage and with shared PV generation among the same type of users, as well as S4-with battery storage and with shared PV generation among different types of users. S1 is taken as a benchmark case, S2 is regarded as a traditional business model, and both S3 and S4 represent sharing business models. With a case study in Beijing, the obtained results show that: (i) sharing business models of S3 and S4, especially S4-with battery storage and with shared PV generation among different types of users, can reduce electricity expenses of the whole community; (ii) sharing business models, especially S4, can obviously enhance the PV self-consumption ratio, indicating a possible way to relieve government's financial burden of feed in tariff; (iii) sharing business models, especially S4, can also improve the economic viability of retired EV batteries significantly, which can help to promote the second-life use and provide references for setting retired EV batteries' prices.

  • 21.
    Wang, L.
    et al.
    SINTEF Energy Research, Trondheim, Norway.
    Skreiberg, Ø.
    SINTEF Energy Research, Trondheim, Norway.
    Khalil, R.
    SINTEF Energy Research, Trondheim, Norway.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Effect of fuel mixing on melting behavior of spruce wood ash2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 1342-1347Conference paper (Refereed)
    Abstract [en]

    The aim of this work was to investigate effects of fuel mixing on melting behavior of spruce wood ash. Spruce bark was studied as additive fuel regarding its ability to lower the melting and flowing temperature of spruce wood ash. Standard ash fusion characterization tests were carried out on ashes from mixtures of spruce wood and bark after heating at 550 °C. The ash residues after the ash fusion tests were analyzed by using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX). High melting temperature and low sintering tendency of spruce wood ash was observed. It is mainly attributed to formation of calcium rich silicates with high melting temperatures. Upon mixing with 10 wt% bark, the melting temperature of the spruce wood ash considerably decreased, which flowed completely after the ash fusion test. Compared to spruce wood ash, SEM images showed that the ash from the mixture of spruce wood and bark passed a molten stage with formation of slag. SEM-EDX revealed that the concentration of silicon in the spruce wood ash increased as a result of mixing with spruce bark. It favors formation of low temperature melting potassium silicates.

  • 22.
    Song, Jingjing
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Effectiveness of introducing heat storage to repress cost increase2019Conference paper (Refereed)
    Abstract [en]

    District heating companies have been adapting their price models to reflect the changes in production cost caused by penetration of renewable fuels, and promote the applications of energy conservation measures that benefit the system efficiency. One of the approaches is to introduce a peak demand component in the price model, which has been proved to be effective to benefit users with lower peak demand. Whereas, this approach also significantly increase the cost for users with high peak demand. One of the measures that could help with high peak demand is installing energy storage on the demand side. In order to understand how the energy storage could change the users’ cost and help DH users to make informed decision, this study analyses the economic benefits of demand-side heat storage, namely if installing low-investment, low-tech, short-term hot-water storage on demand side could effectively repress the cost increase caused by new price models. Five types of building are considered here: multifamily house, commercial building, hospital and social services, industrial building, and office and school. One user of each type, whose costs increased the most during the price model transition process have been included. The result shows that heat storage could efficiently repress the cost increase, and all the investments will be paid back within 3 years, which means introducing heat storage is an efficient measure for cost saving under the circumstances.

  • 23.
    Liu, Shengchun
    et al.
    Tianjin University of Commerce.
    Li, Zheng
    Tianjin University of Commerce.
    Dai, Baomin
    Tianjin University of Commerce.
    Zhong, Zhifeng
    Tianjin University of Commerce.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Song, Mengjie
    Sun, Zhili
    Energetic, economic and environmental analysis of air source transcritical CO2 heat pump system for residential heating in China2019In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 148, p. 1425-1439Article in journal (Refereed)
    Abstract [en]

    Using air source heat pump system for residential heating is a practical way to replace coal-fired boiler in China to alleviate the haze problem, and CO2 is a promising candidate to replace hydrochlorofluorocarbon (HCFC) or hydrofluorocarbon (HFCs) charged into the system. A mathematical model is developed to comprehensively evaluate the energetic, economical and environmental performances of CO2 heat pump system compared with other three traditional heating methods. The results indicate that the primary energy ratio of CO2 heat pump is the highest and it is a rational way to utilize renewable energy with the renewable energy contribution ratio of 0.60–0.69. The initial capital cost of CO2 heat pump is much higher due to the dominant compressor cost. The emission of CO2 heat pump is lower than that of coal-fired boiler at seasonal performance factor above 2.44. The initial and operation cost can be gradually reduced with the mass production and energy efficiency improvement of CO2 heat pump. It is believe that air source CO2 heat pump system can be employed for home heating in China, especial for the hot summer and cold winter region.

  • 24.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zambrano, Jesus
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy demand for phosphorus recovery from municipal wastewater2019In: Innovative Solutions for Energy Transitions / [ed] Elsevier, 2019, Vol. 158, p. 4338-4343Conference paper (Refereed)
    Abstract [en]

    Phosphorus (P) is one of the essential nutrients for production of food. In modern agriculture, a large part of P comes from finite sources. There are several suggested processes for reuse of P from wastewater. In this paper, the energy use of direct reuse of sludge in agriculture is compared to the energy demand connected to use of mineral P and to reuse of P after thermal processing of sludge. The study is based on literature data from life cycle analysis (LCA). In the case of direct sludge reuse the sludge stabilization processes applied and the system boundaries of the LCA has a large impact on the calculated energy demand. The results though indicate that direct reuse of sludge in agriculture is the reuse scenario that potentially has the lowest energy demand (3-71 kWh/kg P), compared to incineration and extraction of P from sludge ashes (45-70 kWh/kg P) or pyrolysis of sludge (46-235 kWh/kg P). The competitiveness compared to mineral P (-4-22 kWh/kg P) depends on the mineral P source and production. For thermal processing, the energy demand derives mainly from energy needed to dry sludge and supplement fuel used during sludge incineration together with chemicals required to extract P. Local conditions, such as available waste heat for drying, can make one of these scenarios preferable.

  • 25.
    Maher, Azaza
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Eskilsson, Anton
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy flow mapping and key performance indicators for energy efficiency support: A case study a sports facility2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 4350-4356Conference paper (Refereed)
    Abstract [en]

    This paper aims to investigate the energy consumption in a sport facilities and elaborate a set of novel energy indicators to support decision making process. Sports facilities are complex systems having higher significant energy demand than other facilities for service and recreation. These facilities require massive demand of various energy (e.g. heat, cooling, electricity) to meet the requirement of different types of sports facilities leading to a high complexity to understand and describe such facility accurately. To tackle this problem, an energy flow mapping of different energy demand is developed to have more insights on the energy flow in both time and space domain within one of the biggest sports facilities in Sweden, Rocklunda arena. All the energy meters are virtually connected to design a comprehensive mapping of the energy streams. Then the data is processed and analyzed to elaborate a set of novel key performance indicators KPIs allowing a simplistic description of the different aspects of the system consumption profile and the related energy performance.

  • 26.
    Zhang, H.
    et al.
    University of Waterloo, Canada.
    Li, X.
    University of Waterloo, Canada.
    Liu, X.
    University of Waterloo, Canada.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Enhancing fuel cell durability for fuel cell plug-in hybrid electric vehicles through strategic power management2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 241, p. 483-490Article in journal (Refereed)
    Abstract [en]

    Fuel cell plug-in hybrid electric vehicles (FC-PHEVs) can have extended range while utilizing cheap grid electricity, but has poor durability of onboard fuel cells due to dynamic loading. In this study, fuel cell durability is enhanced significantly for a novel configuration of FC-PHEVs with three fuel cell stacks through strategic power management by making each fuel cell stack work only at a fixed operating point (i.e., constant output power) and by shortening its active time (operation) via on-off switching control. A hysteresis control strategy of power management is designed to make the active time evenly distributed over the three fuel cell stacks and to reduce the number of on-off switching. The results indicate that the durability of the onboard fuel cells can be increased 11.8, 4.8 and 6.9 times, respectively, for an urban, highway and a combined urban-highway driving cycle. This enhanced fuel cell durability is derived from the fact that the average power demand of real-time driving cycles is only a fraction of the maximum power that FC-PHEVs could provide, and substantially increased durability can be used to reduce the over-design, hence the cost, of fuel cells. 

  • 27.
    Liu, L.
    et al.
    Shandong University, Jinan, China.
    Sun, Q.
    Shandong University, Jinan, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yin, H.
    Shandong University, Jinan, China.
    Ren, X.
    Shandong University, Jinan, China.
    Wennersten, R.
    Shandong University, Jinan, China.
    Evaluating the benefits of Integrating Floating Photovoltaic and Pumped Storage Power System2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 194, p. 173-185Article in journal (Refereed)
    Abstract [en]

    Floating Photovoltaic systems have developed very fast in recent years. Compared to individual Floating Photovoltaic systems, further advantages, such as grid connectivity and energy storage, can be obtained when Floating Photovoltaic operates collaboratively with Pumped Storage Power Systems. This paper proposed an Integrated Floating Photovoltaic-Pumped Storage Power System and quantitatively assessed the potential of the integrated system in electricity generation and conservation of water and land resource. The study developed a coordinated operation model for the Integrated Floating Photovoltaic-Pumped Storage Power System, which employed a dual-objective optimization, namely to maximize the benefits of electricity generation and to minimize the energy imbalance at the same time. The dual-objective optimization was solved using the genetic algorithm method. Other benefits of the Integrated Floating Photovoltaic-Pumped Storage Power System, namely conservation of water and land resource, were also assessed. The proposed methodology was applied to a 2 GW Floating Photovoltaic farm and a 1 GW Pumped Storage Power System. Results indicated that the Integrated Floating Photovoltaic-Pumped Storage Power System has a great potential for gaining the benefits of electricity generation (9112.74 MWh in a typical sunny day averagely) and reducing energy imbalance (23.06 MW aggregately in one day). The coordinated operation provides the possibility to achieve a higher generation benefits without affecting the reliability of the grid, while the optimization method plays a key role of efficient coordination. In addition, the system would help to save 20.16 km 2 land and 19.06 million m 3 water a year due to the reduction in evaporation loss. The synthetic benefits greatly improve the economic and environmental feasibility of photovoltaic systems in reality.

  • 28.
    Daraei, Mahsa
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dotzauer, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Evaluation of biofuel production integrated with existing CHP plants and the impacts on production planning of the system – A case study2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 252, article id 113461Article in journal (Refereed)
    Abstract [en]

    The increasing atmospheric CO2 concentration has caused a transformative shift in global energy systems, which is contributing to an increased use of renewables. Sweden is among the countries trying to shift to a fossil-fuel-free system in all energy sectors. This paper addresses the fuel demand and supply in the transportation sector in the county of Västmanland in Sweden. A Mixed Integer Linear Programming optimization model is developed to minimize cost in the studied system. The model is further used to investigate the influence of three different scenarios on production planning of regional Combined Heat and Power (CHP) plants: (1) straw-based biofuel production integrated with existing CHP plants to fuel combustion engine vehicles, (2) use of electric vehicles, and (3) use of hybrid vehicles fueled by both electricity and bioethanol. Potential solar power generation from rooftop solar cells is also included in the model. The energy system in scenario 2 is found to have the highest overall system efficiency; however, a large amount of power needs to be imported to the system. Hybrid vehicles can potentially reduce the electricity import and CO2 emissions compared to the current situation. Electricity production from rooftop solar collectors could provide the energy needs of the vehicles during summer, while regionally produced straw-based bioethanol integrated with CHP plants can satisfy the fuel needs of the vehicles in winter. This approach could affect the production planning of CHP plants, result in less fuel use and increase the share of renewable resources in the regional transportation system. 

  • 29.
    Mancuso, Martin Vincent
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Evaluation of Grid-Connected Micro-Grid Operational Strategies2019Conference paper (Refereed)
    Abstract [en]

    This study investigates the operational performances of a grid-connected microgrid with integrated solar photovoltaic and battery energy storage. The study is based upon the techno-economic specifications and theoretical performance of the distributed energy resource and storage systems, as well as on measured consumer load data and electrical utility retail and distribution data for representative residential and commercial loads for the city of Västerås, Sweden. The open-source Matlab®-based simulation tool, OptiCE, is used for performing simulations and optimization. To support the attainment of one of the objectives, peak shaving of the consumer load, a battery operational strategy algorithm has been developed to balance peak shaving and PV self-consumption. Comparisons among three types of battery, lead-acid, lithium-ion and vanadium-redox flow, are also performed. A 117 kW p photovoltaic system paired with a lithium-ion battery of 41.1 kWh capacity is the optimal solution found for the considered commercial load. The calculated battery capacity represents the best trade-off for the set multi-objective optimization problem. The simulation of this system predicts the possibility to shave the customer load profile peaks up to 20% for the month of April. The corresponding self-consumption ratio is 88%. Differences in the relationship between the load profiles and the system performance have been qualitatively noted. Furthermore, the simulation results for lead-acid, lithium-ion and vanadium-redox flow battery systems reveal that lithium-ion batteries delivers the best trade-off between total annualized cost and peak shaving performance for both residential and commercial applications.

  • 30.
    Dai, B.
    et al.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Qi, H.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Liu, S.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Ma, M.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Zhong, Z.
    Foreign Economic Cooperation Office, Ministry of Ecology and Environment of the People's Republic of China, Beijing, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Song, M.
    Department of Human and Engineered Environmental Studies, The University of Tokyo, Chiba, Japan.
    Sun, Z.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Evaluation of transcritical CO 2 heat pump system integrated with mechanical subcooling by utilizing energy, exergy and economic methodologies for residential heating2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 192, p. 202-220Article in journal (Refereed)
    Abstract [en]

    A transcritical CO 2 heat pump (HP) system for residential space heating integrated with direct dedicated mechanical subcooling (DMS) is proposed, and mathematical models are developed to study the annual energetic and economic performances considering the influence of frosting. The operation characteristics by adopting different heating terminals used in five typical cities are also assessed. The results show a maximum coefficient of performance (COP) is achieved at the optimum discharge pressure and subcooling degree. The COP is promoted by 24.4% and the discharge pressure is decreased by 2.093 MPa at the ambient temperature of −10 °C and water supply/return temperature of 45/40 °C. The seasonal performance factor (SPF) is enhanced more noticeably for severe cold region. For the case of Harbin using floor-coil radiator (FCR) or normal fan-coil unit (N-FCU) as heating terminal, SPF is improved by 32.0%. The highest SPF is achieved when small temperature difference fan-coil unit (STD-FCU) is employed. The exergy efficiency can also be apparently improved, especially for the cities located in severe cold region and using FCR or N-FCU as heating terminal due to the reduction in throttling loss of CO 2 system. The purchased equipment cost and electricity cost of the CO 2 HP with DMS are both lower than those of traditional CO 2 heat pump system. The CO 2 HP DMS system using STD-FCU as heating terminal shows superior economical efficiency to traditional system, with levelized annual total cost reduced by 7.51–15.27%. 

  • 31.
    Wang, Y.
    et al.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Zhu, K.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Cui, Z.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Wei, J.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Evaluation of water cooling heat sink performance and dynamic flow effect2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 2417-2422Conference paper (Refereed)
    Abstract [en]

    With the advent of high-performance of data centre, the energy consumption of servers has proliferated. Consequently, the generated tremendous amount of heat requires huge energy consumption. Improving energy efficiency is going to play a key role in reducing the energy consumption of data centre. Adopting the heat sink with higher heat transfer and flow performance or precisely control the cooling capacity are two effective way for energy saving in heat dissipation. In this paper, three water cooled heat sink with different pin fin are evaluated by experiments. The heat sink with square pin fin has better heat and flow effect. Meanwhile, the precisely control of the pump power according to the working load is used for energy saving. The energy saving effect is evaluated by benefit factor. However, the most effective way of energy saving is adopting the heat sink with higher comprehensive effect. 

  • 32.
    Zhu, K.
    et al.
    Tianjin Key Laboratory of Refrigeration technology, Tianjin University of Commerce, Tianjin 300134, China.
    Li, X.
    Tianjin Key Laboratory of Refrigeration technology, Tianjin University of Commerce, Tianjin 300134, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Key Laboratory of Refrigeration technology, Tianjin University of Commerce, Tianjin 300134, China.
    Yang, Z.
    Tianjin Key Laboratory of Refrigeration technology, Tianjin University of Commerce, Tianjin 300134, China.
    Wang, Y.
    Tianjin Key Laboratory of Refrigeration technology, Tianjin University of Commerce, Tianjin 300134, China.
    Experimental investigation on the effect of heat sink temperature on operational characteristics of a new-type loop heat pipe2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 2423-2429Conference paper (Refereed)
    Abstract [en]

    With the development of the miniaturization and the high integration of electronic chip, the thermal management of the high power electronic becomes a major challenge. In this paper the influence of heat sink temperature on operational characteristics was comprehensively conducted and the 35% of charging ratio was selected through the experiment study. To evaluate the LHP system, temperatures, start-up time, thermal resistance, and evaporator heat transfer coefficient were selected as performance indicators. The result showed that, there existed an optimal heat sink temperature (18 o C) to obtain the lowest evaporator bottom temperature (77 o C), the shortest start-up time (1000s), the smallest thermal resistance (0.29k/W), and the highest evaporator heat transfer coefficient (3.110 4 W/(m 2 ·k)). The temperature range to keep a high performance of LHP system was 14-20 o C. The conclusion obtained through the experiment can provide the reference of design the cooling system when the LHP system applied into the electric cooling.

  • 33.
    Niu, Z.
    et al.
    Institute of the Building Environment & Sustainability Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China.
    Yu, J.
    Institute of the Building Environment & Sustainability Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China.
    Cui, X.
    Department of Chemical Engineering and Technology/Energy Processes, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden.
    Yang, Xiaohu
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Department of Chemical Engineering and Technology/Energy Processes, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden; Institute of the Building Environment & Sustainability Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China.
    Sun, Y.
    Institute of the Building Environment & Sustainability Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Institute of the Building Environment & Sustainability Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China; Department of Chemical Engineering and Technology/Energy Processes, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden.
    Experimental investigations on the thermal energy storage performance of shell and tube unit with composite phase change materials2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 4889-4896Conference paper (Refereed)
    Abstract [en]

    This work presented experimental investigations on the thermal energy storage performance of the shell and tube unit with composite phase change materials (PCM). A cylindrical heat storage tank filled with open-cell copper foam was proposed and its melting process characteristics were studied. A designed test system was established to record the PCM real-time temperature data. The results showed that, compared with traditional smooth-tube phase-change heat exchangers, the composite PCM unit accelerated the bottom paraffin melting. The temperature disparity among different height reduced, which resulted in better internal temperature uniformity. Due to the expanded heat transfer area, improved heat transfer coefficient and weakened natural convection, the bottom phase-change materials in the composite-PCM heat-storage unit melt faster. 

  • 34.
    Yang, X.
    et al.
    Xi'an Jiaotong University, Xi'an, China.
    Niu, Z.
    Xi'an Jiaotong University, Xi'an, China.
    Bai, Q.
    Xi'an Jiaotong University, Xi'an, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Cui, X.
    Xi'an Jiaotong University, Xi'an, China.
    He, Y. -L
    Xi'an Jiaotong University, Xi'an, China.
    Experimental study on the solidification process of fluid saturated in fin-foam composites for cold storage2019In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 161, article id 114163Article in journal (Refereed)
    Abstract [en]

    Cold storage can effectively turn electricity to cold energy during off peak hours and reduce electricity peak load by supplying cold energy for air conditioning. Solid-liquid phase change rate is seriously encumbered by the relatively-low thermal conductivity of phase change materials (PCMs). A novel fin-foam structure was established to enhance solidification heat transfer and the solidification characteristics were experimentally explored. An experimental system visualizing solid-liquid interface and temperature monitoring was built. The parameters of fin-foam structure, including fin sizes, fin pitch and number were investigated experimentally. Particular attention was paid to justifying the local thermal equilibrium state via measuring temperature on metallic ligament surface and the saturating fluid in pore space. Results showed that inserting fins into metal foam can make a promotional improvement on solidification rate of water by 28.35%. The solid-liquid interface became locally curved after inserting fins. Thermal adhesive and insulation adhesive did not affect the accuracy at pore-scale temperature measurement. Solidification process can be further enhanced through increasing fin width and number rather than fin pitch. © 2019 Elsevier Ltd

  • 35.
    Lu, F.
    et al.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China.
    Liu, S.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China.
    Dai, B.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China.
    Zhong, Z.
    Foreign Economic Cooperation Office, Ministry of Ecology and Environment, Beijing 100035, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Future Energy Center, School of Sustainable Development of Society and Technology, Mälardalen University, Västerås SE-72123, Sweden; Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China.
    Sun, Z.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China.
    Experimental study on thermal performance of transcritical CO 2 air source heat pump for space heating2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 5913-5919Conference paper (Refereed)
    Abstract [en]

    Employing transcritical CO 2 heat pump system for space heating is an effective way to solve the issue of air pollution during the heating season in China. Thus, an experimental setup is developed to study the thermal performance of the transcritical CO 2 air source heat pump system used for space heating. The test results show that a maximum coefficient of performance (COP) of 2.88 is obtained at the optimum discharge pressure and the ambient temperature of 10 o C. The optimal high pressure is nearly a constant with the value of about 8.5 MPa for the ambient temperature in the range of -15~10 o C. The system COP increases with the ambient temperature increasing, and the outlet temperature of the gas cooler is a dominant influencing factor on the thermal performance of the heat pump system. Little difference can be found between the gas cooler outlet temperatures with the variation in ambient temperatures.

  • 36.
    Ekman, Peter
    et al.
    Mälardalen University, School of Business, Society and Engineering, Industrial Economics and Organisation.
    Röndell, Jimmie
    Mälardalen University, School of Business, Society and Engineering, Industrial Economics and Organisation.
    Yang, Ying
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Exploring smart cities and market transformations from a service-dominant logic perspective2019In: Sustainable cities and society, ISSN 2210-6707, Vol. 51, article id 101731Article in journal (Refereed)
    Abstract [en]

    This study addresses the emergence of new actors and their roles in the transformation of smart cities. By building on a Service-Dominant logic perspective, the study capture how smart city transformation is closely related to a smart market transformation. While prior conceptualizations of markets have followed a linear supply-demand structure, the new market conceptualization can be described as a service ecosystem. The study empirically follows the increased use of renewable energy, such as photovoltaic (PV) systems and their related services, as they are incorporated into smart cities. The results reveal that the overall interaction level among the involved actors increases as the energy market changes from a linear to a networked logic. This transition impacts the market's information quality and, subsequently, the actors’ level of required knowledge. The study shows that even if the prevailing actors become more informed, information needs to be ‘translated’ into ‘knowledge-in-context’ to become a valuable resource. Thus, the resulting service ecosystem demands a complementary actor that requires the role of a knowledge broker to function. The paper describes the mechanisms behind this smart city transformation and clarifies the broker functions.

  • 37.
    Bian, Caiyun
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lin, L.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Beijing, 102249, China.
    Yu, Z.
    Department of Energy and Petroleum EngineeringUniversity of Stavanger, Norway.
    Finding the optimal location for public charging stations - A GIS-based MILP approach2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 6582-6588Conference paper (Refereed)
    Abstract [en]

    Electric Vehicles (EVs) have achieved a significant development because of the continuous technology revolution and policy supports in recent years, which leads to a larger demand of charging stations. Strategies about how to find the optimal location for charging facilities are urgently needed in order to further assist the development of EVs. This paper focus on the return of investments on EV charging stations and proposes a Mixed Integer Linear Programming (MILP) model based on Geographic Information System (GIS) to identify the optimal location of charging stations in cities. Traffic flow data and land-use classifications are used as important inputs, and six important constraints are included in the MILP model with the objective function of maximizing the total profits of new charging stations. The effectiveness of the proposed method is then demonstrated by implementing a case study in Västerås, Sweden.

  • 38.
    Hennessy, Jay
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. RISE Research Institutes of Sweden, Box 857, SE-501 15 Borås, Sweden.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Flexibility in thermal grids: A review of short-term storage in district heating distribution networks2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 2430-2434Conference paper (Refereed)
    Abstract [en]

    Future energy systems need to be more flexible. The use of cross-sector coupling in combination with thermal storage in thermal grids has been shown to provide such flexibility. The presented study reviews how short-term storage in district heating distribution networks is used or modelled for flexibility, what are the most important parameters, and where the knowledge gaps remain. The results show that the potential for flexibility from district heating has not been fully exploited. Sensible thermal storage tanks are 50-100 times cheaper than electrical storage and storage in the distribution network requires little additional investment in infrastructure. In some countries, the majority of district heating systems have sensible thermal storage tanks, with as much as 64 % of their capacity available for flexibility services. Initial results suggest that only smaller networks are prevented from using the distribution network for storage, but the impacts of this type of use on the physical components and the capacity limitations remain unclear and show a need for standardised methods for analysis. There is a growing interest, both in Europe and China, in the use of short-term storage in district heating to provide flexibility, particularly in the form of ancillary services to the electricity grid, but implementations of these techniques are rare. The presented study identifies a number of remaining knowledge gaps that should be addressed in order to harness available flexibility in district heating.

  • 39.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB, Västers, Sweden.
    Struhar, Vaclav
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fogification of industrial robotic systems: Research challenges2019In: IoT-Fog 2019 - Proceedings of the 2019 Workshop on Fog Computing and the IoT, Association for Computing Machinery, Inc , 2019, p. 41-45Conference paper (Refereed)
    Abstract [en]

    To meet the demands of future automation systems, the architecture of traditional control systems such as the industrial robotic systems needs to evolve and new architectural paradigms need to be investigated. While cloud-based platforms provide services such as computational resources on demand, they do not address the requirements of real-time performance expected by control applications. Fog computing is a promising new architectural paradigm that complements the cloud-based platform by addressing its limitations. In this paper, we analyse the existing robot system architecture and propose a fog-based solution for industrial robotic systems that addresses the needs of future automation systems. We also propose the use of Time-Sensitive Networking (TSN) services for real-time communication and OPC-UA for information modelling within this architecture. Additionally, we discuss the main research challenges associated with the proposed architecture.

  • 40.
    Kanders, Linda
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Purac AB, Sweden.
    Yang, Jing-jing
    IVL Swedish Environmental Research Institute, Sweden.
    Baresel, Christian
    IVL Swedish Environmental Research Institute, Sweden.
    Zambrano, Jesus
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Full-scale comparison of N2O emissions from SBR N/DN operation versus one-stage deammonification MBBR treating reject water: - and optimization with pHset-point2019In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 79, no 8, p. 1616-1625Article in journal (Refereed)
    Abstract [en]

    To be able to fulfill the Paris agreement regarding anthropogenic greenhouse gases, all potential 12 emissions must be mitigated. Wastewater treatment plants should aim to eliminate emissions of the 13 most potent greenhouse gas, nitrous oxide. In this study, these emissions were measured at a full-scale 14 reject water treatment tank during two different operation modes: nitrification/denitrification (N/DN) 15 operating as a sequencing batch reactor (SBR), and deammonification (nitritation/anammox) as a moving 16 bed biofilm reactor (MBBR). Nitrous oxide was measured both in the water phase and in the off-gas. The 17 treatment process emitted significantly less nitrous oxide in deammonification mode 0.14-0.7 %, 18 compared to 10 % of Total Nitrogen in N/DN mode. The decrease can be linked to the change feeding 19 strategy, concentration in nitrite, load of ammonia oxidized, shorter aeration time, no ethanol dosage 20 and the introduction of biofilm. Further, evaluation was done how the operational pH set point 21 influenced the emissions in deammonification mode. Lower concentrations of nitrous oxide was 22 measured in water phase at higher pH (7.5-7.6) than at lower pH (6.6-7.1). This is believed to be mainly 23 because of the lower aeration ratio and increased complete denitrification at the higher pH set point.

  • 41.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH.
    Identification of thermochemical pathways for the energy and nutrient recovery from digested sludge in wastewater treatment plants2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 1317-1322Conference paper (Refereed)
    Abstract [en]

    There are several restrictions and limitations on the emissions and disposal of materials and pollutants related to wastewater treatment plants (WWTPs) emphasizing improvement of current processes and development of new methods. Process integration is one way to use all fractions of waste for improved efficiency. WWTPs produces sludge which is usually anaerobically digested to produce biogas and a byproduct called digestate. Digestate is an organic material that contains macro and micronutrients such as nitrogen, phosphorous, and potassium and also contains heavy metals. Digestate is mainly used for agricultural applications because of the presence of nutrients. However, digestate also contains energy in the form of carbon and hydrogen which can be harnessed through various processes and integrated with nitrogen recovery process. This study aims to recover the energy and nutrients from digestate through thermochemical treatment processes. Combustion, pyrolysis, and gasification are assessed and compared in this work. An ammonia stripping method is assumed to recover nitrogen from digestate. The thermochemical processes are heat integrated with ammonia stripping through modeling and simulation. Results show that almost half of the energy present in digested sludge is required for its drying. Moreover, nitrogen recovery also requires much energy. The combustion and gasification of digested sludge give better results than pyrolysis. The heat integration becomes feasible when the auxiliary biogas is also burned along with products from the thermochemical treatment of sludge.

  • 42. Tan, Y.
    et al.
    Nookuea, Worrada
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Impacts of thermos-physical properties on plate-fin multi-stream heat exchanger design in cryogenic process for CO2 capture2019In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 149, p. 1445-1453Article in journal (Refereed)
    Abstract [en]

    Oxy-fuel combustion is one of the most promising technologies for CO2 capture for power plants. In oxy-fuel combustion plants, cryogenic process can be applied for CO2 purification because the main impurities in flue gas are non-condensable gases. The multi-stream plate-fin heat exchanger is one of the most important components in the CO2 cryogenic system. In-depth understanding of the impacts of property on the heat exchanger is of importance for appropriate design. In order to investigate the impacts of properties on sizing the heat exchanger and to further identify the key properties to be prioritized for the property model development, this paper presented the design procedure for the plate-fin multi-stream heat exchanger for the CO2 cryogenic process. Sensitivity study was conducted to analyze the impacts of thermos-physical properties including density, viscosity, heat capacity and thermal conductivity. The results show that thermal conductivity has the most significant impact and hence, developing a more accurate thermal conductivity model is more important for the heat exchanger design. In addition, even though viscosity has less significant impact compared to other properties, the larger deviation range of current viscosity models may lead to higher uncertainties in volume design and annual capital cost of heat exchanger. 

  • 43.
    Yan, Jinyue
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. School of Chemical Science and Engineering, Royal Institute of Technology, 100 44 Stockholm, Sweden.
    Yang, H.
    Department of Building Services Engineering, The Hong Kong Polytechnic University.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Chen, X.
    Department of Building Services Engineering, The Hong Kong Polytechnic University.
    Innovative solutions for energy transitions: Proceedings of the 10th International Conference on Applied Energy (ICAE2018)2019In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 158, p. 1-2Article in journal (Other academic)
  • 44.
    Siyuan, C.
    et al.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Qi, Z.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Yanyan, T.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Boyu, L.
    Academy of Chinese Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Investment strategy for shallow geothermal resource based on real option model2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 6118-6125Conference paper (Refereed)
    Abstract [en]

    Shallow geothermal resource has been considered as a new and promising form for clean heating in some areas in China, such as Xiong'an New Area. In this paper, a real option model is established to explore the optimal investment timing and investment scale of shallow geothermal resources. According to numerical results, we found that in the reference scenario the critical value of marginal revenue is 4.30 yuan / m 2 , and the optimal investment scale is 1.28 million square meters. Simultaneously, the investors are advised to invest after 1.05 years and they will get the unit investment return of 39.34 yuan / m 2

  • 45.
    Fell, Terence
    et al.
    Mälardalen University, School of Business, Society and Engineering, Industrial Economics and Organisation.
    Guziana, Bozena
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Elander, Ingemar
    Mälardalen University, School of Business, Society and Engineering, Industrial Economics and Organisation.
    Klass, rumslig segration och livskvalitet i två svenska städer2019In: Statsvetenskaplig Tidskrift, ISSN 0039-0747, Vol. 121, no 1, p. 65-93Article in journal (Refereed)
    Abstract [en]

    Against a background of decades of spatial class segregation in Sweden and elsewhere, and with the Swedish city as our empirical base, we demonst rate how classposition effects residents’ life chances defined here as health, security, participation, and education. By comparing the circumstances of affluent neighbourhoodsin both cities with those of disadvantaged neighbourhoods we elucidate important changes in a modern city’s class hierarchy like increased social polarization.We conclude, firstly, that those neighbourhoods that change class position do soslowly and are becoming predominantly middle class. Secondly, we show that thesituation in both cities’ low income neighbourhood category varies dramatically.Finally, and in contradiction with mainstream urban theory, we infer that growingsocial inequality is not always detrimental to the lives of residents in disadvantagedneighbourhoods

  • 46.
    Swing Gustafsson, Moa
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Dalarna University, Sweden.
    Myhren, J. A.
    Dalarna University, Sweden.
    Dotzauer, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Gustafsson, M.
    Linköping University, Sweden.
    Life cycle cost of building energy renovation measures, considering future energy production scenarios2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 14, article id 2719Article in journal (Refereed)
    Abstract [en]

    A common way of calculating the life cycle cost (LCC) of building renovation measures is to approach it from the building side, where the energy system is considered by calculating the savings in the form of less bought energy. In this study a wider perspective is introduced. The LCC for three different energy renovation measures, mechanical ventilation with heat recovery and two different heat pump systems, are compared to a reference case, a building connected to the district heating system. The energy system supplying the building is assumed to be 100% renewable, where eight different future scenarios are considered. The LCC is calculated as the total cost for the renovation measures and the energy systems. All renovation measures result in a lower district heating demand, at the expense of an increased electricity demand. All renovation measures also result in an increased LCC, compared to the reference building. When aiming for a transformation towards a 100% renewable system in the future, this study shows the importance of having a system perspective, and also taking possible future production scenarios into consideration when evaluating building renovation measures that are carried out today, but will last for several years, in which the energy production system, hopefully, will change.

  • 47.
    Lu, H.
    et al.
    East China University of Science and Technology, Shanghai, China.
    Yu, X.
    East China University of Science and Technology, Shanghai, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tu, S. -T
    East China University of Science and Technology, Shanghai, China.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lipids extraction from wet Chlorella pyrenoidosa sludge using recycled [BMIM]Cl2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 291, article id 121819Article in journal (Refereed)
    Abstract [en]

    In this study, experiments on pretreating one species of microalgae (Chlorella pyrenoidosa) using one kind of ionic liquid (IL) of [BMIM]Cl were conducted. The aim of this work is to evaluate the recycling efficacy of expensive IL solvent for effective cell disruption. It was indicated that the molecular structure of IL was stable during the recycling test. Five times antisolvent precipitation of microalgae debris after lipid extraction using methanol recovered 99.8% IL with the energy consumption of 4.46 MJ per kg dry Chlorella pyrenoidosa. The chromatography was used to separate IL and hydrolysates, resulting in the IL loss below 1.97 g per kg dry Chlorella pyrenoidosa. © 2019 Elsevier Ltd

  • 48.
    Zambrano, Jesus
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Samuelsson, Oscar
    IVL Swedish Environm Res Inst, Stockholm, Sweden.
    Carlsson, Bengt
    Uppsala Univ, Sweden.
    Machine learning techniques for monitoring the sludge profile in a secondary settler tank2019In: Applied water science, ISSN 2190-5487, E-ISSN 2190-5495, Vol. 9, no 6, article id UNSP 146Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to evaluate and compare the performance of two machine learning methods, Gaussian process regression (GPR) and Gaussian mixture models (GMMs), as two possible methods for monitoring the sludge profile in a secondary settler tank (SST). In GPR, the prediction of the response variable is given as a Gaussian probability density function, whereas in the GMM the probability density function is built as a weighted sum of Gaussian distributions. In both approaches, a residual is calculated and a fault detection criterion is implemented via a recursive decision rule. As case study, GMM and GPR were tested using real data from a sensor measuring the suspended solids concentration as a function of the SST level in a wastewater treatment plant in Bromma, Sweden. Results suggest that GMM gives a faster response but is also more sensitive than GPR to changes during normal conditions.

  • 49.
    Yan, J.
    et al.
    North China Electric Power University, Beijing, 102206, China.
    Lai, F.
    North China Electric Power University, Beijing, 102206, China.
    Liu, Y.
    North China Electric Power University, Beijing, 102206, China.
    Yu, D. C.
    University of Wisconsin – Milwaukee, United States.
    Yi, W.
    Energy Research Institute of National Development and Reform Commission, China.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH-Royal Institute of Technology, Sweden.
    Multi-stage transport and logistic optimization for the mobilized and distributed battery2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 196, p. 261-276Article in journal (Refereed)
    Abstract [en]

    High share of variable renewable energy is challenging to the traditional power system technically and economically. This calls for a significant increase to the system flexibility, which might result in the costs associated with energy storage and costly upgrades to the traditional transmission and distribution system. This paper presents a multi-stage battery transportation and logistics optimization method to increase the renewable energy consumptions, economics, and mobilities of the battery utilization. A new approach is proposed in which the batteries are charged in the renewable power plants and transported back and forth by railways between the renewable power plants and cities. Based on the forecasts of battery supplies/demands, multiple optimization stages (full train transport and carpooling) are designed by the branch-and-bound algorithm and genetic algorithm respectively. The proposed battery transportation and logistics concept and model are performed using the Beijing-Tianjin-Hebei region in China as an example. The results show that the levelized cost of energy of the battery transportation and logistics model is $0.045/kWh averagely. Also, by the use of mobilized batteries, the proposed battery transportation and logistics model increases the system flexibilities and renewable energy deliveries to the end users without the reinforcement of transmission and distribution system and any constraint from a highly penetrated power system.

  • 50.
    Wang, C.
    et al.
    Tongji University, Shanghai, China.
    Du, Y.
    Tongji University, Shanghai, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wallin, Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Min, G.
    University of Exeter, Exeter, United Kingdom.
    New methods for clustering district heating users based on consumption patterns2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 251, article id 113373Article in journal (Refereed)
    Abstract [en]

    Understanding energy users’ consumption patterns benefits both utility companies and consumers as it can support improving energy management and usage strategies. The rapid deployment of smart metering facilities has enabled the analysis of consumption patterns based on high-precision real usage data. This paper investigates data-driven unsupervised learning techniques to partition district heating users into separate clusters such that users in the same cluster possess similar consumption pattern. Taking into account the characteristics of heat usage, three new approaches of extracting pattern features from consumption data are proposed. Clustering algorithms with these features are executed on a real-world district heating consumption dataset. The results can reveal typical daily consumption patterns when the consumption linearly related to ambient temperature is removed. Users with heat usages that are highly imbalanced within a certain period of time or are highly consistent with the utility heat production load can also be grouped together. Our methods can facilitate gaining better knowledge regarding the behaviors of district heating users and hence can potentially be used to formulate new pricing and energy reduction solutions.

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