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  • 1. Belleri, Annamaria
    et al.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Saini, Puneet
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Sanchez de soria, Tomas
    Solarwall.
    Paolo, Bonato
    EURAC.
    Adami, Jennifer
    D4.2 Solar assisted ventilation2020Rapport (Annet vitenskapelig)
  • 2. Cao, x
    et al.
    Yuan, Y
    Xiang, B
    Sun, L
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Numerical investigation on optimal number of longitudinal fins in horizontal annular phase change unit at different wall temperatures2018Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 158, s. 384-392Artikkel i tidsskrift (Fagfellevurdert)
  • 3. Chang, Li
    et al.
    Chong, Wen Tong
    Wang, Xinru
    Pei, Fei
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Wang, Tongzhao
    Wang, Chunqing
    Pan, Song
    Recent progress in research on PM2.5 in subways.2021Inngår i: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 23, nr 5, s. 642-663Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nowadays, PM2.5 concentrations greatly influence indoor air quality in subways and threaten passenger and staff health because PM2.5 not only contains heavy metal elements, but can also carry toxic and harmful substances due to its small size and large specific surface area. Exploring the physicochemical and distribution characteristics of PM2.5 in subways is necessary to limit its concentration and remove it. At present, there are numerous studies on PM2.5 in subways around the world, yet, there is no comprehensive and well-organized review available on this topic. This paper reviews the nearly twenty years of research and over 130 published studies on PM2.5 in subway stations, including aspects such as concentration levels and their influencing factors, physicochemical properties, sources, impacts on health, and mitigation measures. Although many determinants of station PM2.5 concentration have been reported in current studies, e.g., the season, outdoor environment, and station depth, their relative influence is uncertain. The sources of subway PM2.5 include those from the exterior (e.g., road traffic and fuel oil) and the interior (e.g., steel wheels and rails and metallic brake pads), but the proportion of these sources is also unknown. Control strategies of PM mainly include adequate ventilation and filtration, but these measures are often inefficient in removing PM2.5. The impacts of PM2.5 from subways on human health are still poorly understood. Further research should focus on long-term data collection, influencing factors, the mechanism of health impacts, and PM2.5 standards or regulations.

  • 4. Chen, X
    et al.
    Su, Y
    Aydin, D
    Bai, H
    Jarimi, H
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Raffat, S
    Experimental investigation of a polymer hollow fibre integrated liquid desiccant dehumidification system with aqueous potassium formate solution2018Inngår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hollow fibres have been studied as the substitute for metallic materials due to the advantages such as light weight, corrosion resistant and low cost in heat and mass transfer applications. A novel polymer hollow fibre liquid desiccant dehumidification system, in which a cross-flow hollow fibre module (fibre inside diameter=1.4mm) serves as the dehumidifier, is presented in this paper. This novel hollow fibre integrated liquid desiccant dehumidification system can be used in an air conditioning system to provide a comfortable indoor environment for hot and humid area. Compared with other conventional liquid desiccant dehumidifier, the polymer hollow fibre has a very small diameter which leads to significantly increased surface area. Moreover, the porous feature of the hollow fibre module can help to eliminate any liquid desiccant droplets carryover into the process air. As a less corrosive and more environmental friendly working fluid, aqueous potassium formate (KCOOH) solution has been selected. The dehumidification performance of the proposed system were analysed experimentally under the conditions of incoming air temperature in the range of 30°C to 45°C. The variations of dehumidification sensible and latent effectiveness, moisture removal rates were studied by varying the incoming air velocity from 0.65 m/s to 4.5m/s. With the various values of incoming air relative humidity in the range of 55% to 75% and the solution concentrations between 36% and 62%, the experimental obtained latent effectiveness are in the range of 0.25 to 0.43 and the sensible effectiveness are in the range of 0.31 to 0.52, which is in a satisfactory agreement with the empirical correlation of effectiveness-NTU in the literature.

  • 5. Chen, X.
    et al.
    Su, Y.
    Aydin, D.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Ding, Y.
    Reay, D.
    Law, R.
    Riffat, S.
    Experimental investigations of polymer hollow fibre integrated evaporative cooling system with the fibre bundles in a spindle shape2017Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 154, s. 166-174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to the advantages of light weight, corrosion resistant and low cost, hollow fibres have been studied as the substitute for metallic materials. A novel hollow fibre integrated evaporative cooling system, in which the hollow fibre module constitutes as the humidifier and the evaporative cooler, is proposed. This novel hollow fibre integrated evaporative cooling system will provide a comfortable indoor environment for hot and dry area. Moreover, the water vapour can permeate through the hollow fibre effectively, and the liquid water droplets will be prevented from mixing with the processed air. In order to avoid the flow channelling or shielding of adjacent fibres, the fibres inside each bundle were made into a spindle shape to allow maximum contact between the air stream and the fibre. The cooling performances of the proposed novel polymer hollow fibre integrated evaporative cooling system were experimentally investigated under the incoming air temperature in the range of 26 °C to 32 °C and relative humidity of 25%–35%. The effects of air velocities on the cooling effectiveness, heat and mass transfer coefficients, specific water consumption and pressure drop across the polymer hollow fibre module were analysed. Two sets of experimentally derived non-dimensional heat and mass transfer correlations were summarized, which could be favourable for the future design of polymer hollow fibre integrated evaporative cooling system.

  • 6. Copertaro, Benedetta
    et al.
    Shen, Jingchun
    Högskolan Dalarna, Institutionen för information och teknik, Byggteknik.
    Sangelantoni, Lorenzo
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Building Renovation Adapting to Future Climate: A Potential Solution of Phase-Change Material to Building Envelope2022Inngår i: Handbook of Climate Change Mitigation and Adaptation / [ed] Maximilian Lackner, Baharak Sajjadi, Wei-Yin Chen, Springer Nature, 2022Kapittel i bok, del av antologi (Fagfellevurdert)
  • 7. Dong, Bing
    et al.
    Liu, Yapan
    Fontenot, Hannah
    Ouf, Mohamed
    Osman, Mohamed
    Chong, Adrian
    Qin, Shuxu
    Han, Mengjie
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Carlucci, Salvatore
    Occupant behavior modeling methods for resilient building design,operation and policy at urban scale: a review2021Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 293, artikkel-id 116856Artikkel i tidsskrift (Fagfellevurdert)
  • 8. Duan, Zhiyin
    et al.
    Zhan, Changhong
    Zhang, Xingxing
    De Montfort University.
    Mustafa, Mahmud
    Zhao, Xudong
    Alimohammadisagvand, Behrang
    Hasan, Ala
    Indirect evaporative cooling: Past, present and future potentials2012Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 16, nr 9, s. 6823-6850Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reported a review based study into the Indirect Evaporative Cooling (IEC) technology, which was undertaken from a variety of aspects including background, history, current status, concept, standardisation, system configuration, operational mode, research and industrialisation, market prospect and barriers, as well as the future focuses on R&D and commercialisation. This review work indicated that the IEC technology has potential to be an alternative to conventional mechanical vapour compression refrigeration systems to take up the air conditioning duty for buildings. Owing to the continuous progress in technology innovation, particularly the M-cycle development and associated heat and mass transfer and material optimisation, the IEC systems have obtained significantly enhanced cooling performance over those the decade ago, with the wet-bulb effectiveness of greater than 90% and energy efficiency ratio (EER) up to 80. Structure of the IEC heat and mass exchanger varied from flat-plate-stack, tube, heat pipe and potentially wave-form. Materials used for making the exchanger elements (plate/tube) included fibre sheet with the single side water proofing, aluminium plate/tube with single side wicked setting (grooved, meshed, toughed etc), and ceramic plate/tube with single side water proofing. Counter-current water flow relevant to the primary air is considered the favourite choice; good distribution of the water stream across the wet surface of the exchanger plate (tube) and adequate (matching up the evaporation) control of the water flow rate are critical to achieving the expected system performance. It was noticed that the IEC devices were always in combined operation with other cooling measures and the commonly available IEC related operational modes are (1) IEC/DEC system; (2) IEC/DEC/mechanical vapour compression system; (3) IEC/desiccant system; (4) IEC/chilled water system; and (5) IEC/heat pipe system. The future potential operational modes may also cover the IEC-inclusive fan coil units, air handle units, cooling towers, solar driven desiccant cycle, and Rankine cycle based power generation system etc. Future works on the IEC technology may focus on (1) heat exchanger structure and material; (2) water flowing, distribution and treatment; (3) incorporation of the IEC components into conventional air conditioning products to enable combined operation between the IEC and other cooling devices; (4) economic, environment and social impacts; (5) standardisation and legislation; (6) public awareness and other dissemination measures; and (7) manufacturing and commercialisation. All above addressed efforts may help increase the market ratio of the IEC to around 20% in the next 20 years, which will lead to significant saving of fossil fuel consumption and cut of carbon emission related to buildings.

  • 9. Freitas, Iuri
    et al.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Green building rating systems in Swedish market: A comparative analysis between LEED, BREEAM SE, GreenBuilding and Miljöbyggnad2018Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 153, s. 402-407Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Sweden, there are four most commonly used green building rating systems, which are LEED, BREEAM SE, GreenBuilding and Miljöbyggnad. In this study, each of them is analyzed under the aspects of certification process, implementation cost, educational needs and the variety of categories. SWOT method is further applied to extract the strengths, weaknesses, opportunities and threats of each of the rating system in a direct and indirect manner, making it clearer to choose among various options when considering the individual needs of each project in practice. 

    Fulltekst (pdf)
    fulltext
  • 10. Gao, D. -C
    et al.
    Sun, Y.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Huang, Pei
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Zhang, Yelin
    A GA-based NZEB-cluster planning and design optimization method for mitigating grid overvoltage risk2022Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 243, artikkel-id 123051Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Net-zero energy buildings (NZEBs) are considered as a promising method to mitigating the energy problems. Due to the intermittent characteristics of renewable energy (e.g., solar energy), NZEBs need to frequently exchange energy with the grid, which imposes severe negative impacts on the grid especially the overvoltage risk. Both planning and design are essential for reducing NZEB connected grid overvoltage, but most existing studies isolated the efforts from planning to design, thereby failing to achieve the best cumulative result. More importantly, existing studies oversimplified overvoltage quantification by using aggregated power interactions to represent overvoltage risk, which cannot consider the complex voltage influences among grid nodes. Due to the isolated efforts and the quantification oversimplification, existing studies can hardly achieve overvoltage risk minimization. Therefore, this study proposes a novel GA (genetic algorithm)-based method in which the key planning and design parameters are optimized sequentially for mitigating the overvoltage risk. Meanwhile, distribution network model has been adopted to precisely quantify the grid overvoltage. The study results show that the proposed method is highly effective in reducing NZEB cluster connected grid overvoltage risk. The proposed method can be used in practice for improving NZEB cluster planning and system design as grid interaction is considered. © 2021 Elsevier Ltd

  • 11. Gorjian, Shiva
    et al.
    Calise, Francesco
    Kant, Karunesh
    Ahamed, Md Shamim
    Copertaro, Benedetta
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Najafi, Gholamhassan
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Aghaei, Mohammadreza
    Shamshiri, Redmond R.
    A review on opportunities for implementation of solar energy technologies in agricultural greenhouses2021Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 285, artikkel-id 124807Artikkel i tidsskrift (Fagfellevurdert)
  • 12. Gu, Yaxiu
    et al.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Myhren, Jonn Are
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Han, Mengjie
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Chen, Xiangjie
    Yuan, Yanping
    Techno-economic analysis of a solar photovoltaic/thermal (PV/T) concentrator for building application in Sweden using Monte Carlo method2018Inngår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 165, s. 8-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solar energy share in Sweden will grow up significantly in next a few decades. Such transition offers not only great opportunity but also uncertainties for the emerging solar photovoltaic/thermal (PV/T) technologies. This paper therefore aims to conduct a techno-economic evaluation of a reference solar PV/T concentrator in Sweden for building application. An analytical model is developed based on the combinations of Monte Carlo simulation techniques and multi energy-balance/financial equations, which takes into account of the integrated uncertainties and risks of various variables. In the model, 11 essential input variables, i.e. average daily solar irradiance, electrical/thermal efficiency, prices of electricity/heating, operation & management (OM) cost, PV/T capital cost, debt to equity ratio, interest rate, discount rate, and inflation rate, are considered, while the economic evaluation metrics, such as levelized cost of energy (LCOE), net present value (NPV), and payback period (PP), are primarily assessed. According to the analytical results, the mean values of LCOE, NPV and PP of the reference PV/T connector are observed at 1.27 SEK/kW h (0.127 €/kW h), 18,812.55 SEK (1881.255 €) and 10 years during its 25 years lifespan, given the project size at 10.37 m2 and capital cost at 4482–5378 SEK/m2 (448.2–537.8 €/m2). The positive NPV indicates that the investment on the selected PV/T concentrator will be profitable as the projected earnings exceeds the anticipated costs, depending on the NPV decision rule. The sensitivity analysis and the parametric study illustrate that the economic performance of the reference PV/T concentrator in Sweden is mostly proportional to solar irradiance, debt to equity ratio and heating price, but disproportionate to capital cost and discount rate. Together with additional market analysis of PV/T technologies in Sweden, it is expected that this paper could clarify the economic situation of PV/T technologies in Sweden and provide a useful model for their further investment decisions, in order to achieve sustainable and low-carbon economics, with an expanded quantitative discussion of the real economic or policy scenarios that may lead to those outcomes.

  • 13.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Canli, Ilkim
    Department of Architecture, Middle East Technical University, Ankara 06800, Türkiye;Center for Solar Energy Research and Applications (ODTÜ-GÜNAM), Middle East Technical University, Ankara 06800, Türkiye.
    Shah, Juveria
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Dino, Ipek Gursel
    Department of Architecture, Middle East Technical University, Ankara 06800, Türkiye;METU Robotics and AI Technologies Application and Research Center (METU-ROMER), Middle East Technical University (METU), Ankara 06800, Türkiye.
    Kalkan, Sinan
    METU Robotics and AI Technologies Application and Research Center (METU-ROMER), Middle East Technical University (METU), Ankara 06800, Türkiye;Department of Computer Engineering, Middle East Technical University, Ankara 06800, Türkiye.
    Perspectives of Machine Learning and Natural Language Processing on Characterizing Positive Energy Districts2024Inngår i: Buildings, E-ISSN 2075-5309, Vol. 14, nr 2, artikkel-id 371Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concept of a Positive Energy District (PED) has become a vital component of the efforts to accelerate the transition to zero carbon emissions and climate-neutral living environments. Research is shifting its focus from energy-efficient single buildings to districts, where the aim is to achieve a positive energy balance across a given time period. Various innovation projects, programs, and activities have produced abundant insights into how to implement and operate PEDs. However, there is still no agreed way of determining what constitutes a PED for the purpose of identifying and evaluating its various elements. This paper thus sets out to create a process for characterizing PEDs. First, nineteen different elements of a PED were identified. Then, two AI techniques, machine learning (ML) and natural language processing (NLP), were introduced and examined to determine their potential for modeling, extracting, and mapping the elements of a PED. Lastly, state-of-the-art research papers were reviewed to identify any contribution they can make to the determination of the effectiveness of the ML and NLP models. The results suggest that both ML and NLP possess significant potential for modeling most of the identified elements in various areas, such as optimization, control, design, and stakeholder mapping. This potential is realized through the utilization of vast amounts of data, enabling these models to generate accurate and useful insights for PED planning and implementation. Several practical strategies have been identified to enhance the characterization of PEDs. These include a clear definition and quantification of the elements, the utilization of urban-scale energy modeling techniques, and the development of user-friendly interfaces capable of presenting model insights in an accessible manner. Thus, developing a holistic approach that integrates existing and novel techniques for PED characterization is essential to achieve sustainable and resilient urban environments.

    Fulltekst (pdf)
    fulltext
  • 14.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Johari, Fatemeh
    Uppsala University.
    Huang, Pei
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Generating hourly electricity demand data for large-scale single-family buildings by a decomposition-recombination method2022Inngår i: Energy and Built Environment, ISSN 2666-1233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Household electricity demand has substantial impacts on local grid operation, energy storage and the energy performance of buildings. Hourly demand data at district or urban level helps stakeholders understand the demand patterns from a granular time scale and provides robust evidence in energy management. However, such type of data is often expensive and time-consuming to collect, process and integrate. Decisions built upon smart meter data have to deal with challenges of privacy and security in the whole process. Incomplete data due to confidentiality concerns or system failure can further increase the difficulty of modeling and optimization. In addition, methods using historical data to make predictions can largely vary depending on data quality, local building environment, and dynamic factors. Considering these challenges, this paper proposes a statistical method to generate hourly electricity demand data for large-scale single-family buildings by decomposing time series data and recombining them into synthetics. The proposed method used public data to capture seasonality and the distribution of residuals that fulfill statistical characteristics. A reference building was used to provide empirical parameter settings and validations for the studied buildings. An illustrative case in a city of Sweden using only annual total demand was presented for deploying the proposed method. The results showed that the proposed method can mimic reality well and represent a high level of similarity to the real data. The average monthly error for the best month reached 15.9% and the best one was below 10% among 11 tested months. Less than 0.6% improper synthetic values were found in the studied region.

  • 15.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    May, Ross
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Reinforcement Learning Methodologies for Controlling Occupant Comfort in Buildings2021Inngår i: Data-driven Analytics for Sustainable Buildings and Cities, Switzerland: Springer, 2021, s. 179-205Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 16.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    May, Ross
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wang, Xinru
    Pan, Song
    Da, Yan
    Jin, Yuan
    A novel reinforcement learning method for improving occupant comfort via window opening and closing2020Inngår i: Sustainable cities and society, ISSN 2210-6707, Vol. 61, artikkel-id 102247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An occupant's window opening and closing behaviour can significantly influence the level of comfort in the indoor environment. Such behaviour is, however, complex to predict and control conventionally. This paper, therefore, proposes a novel reinforcement learning (RL) method for the advanced control of window opening and closing. The RL control aims at optimising the time point for window opening/closing through observing and learning from the environment. The theory of model-free RL control is developed with the objective of improving occupant comfort, which is applied to historical field measurement data taken from an office building in Beijing. Preliminary testing of RL control is conducted by evaluating the control method’s actions. The results show that the RL control strategy improves thermal and indoor air quality by more than 90 % when compared with the actual historically observed occupant data. This methodology establishes a prototype for optimally controlling window opening and closing behaviour. It can be further extended by including more environmental parameters and more objectives such as energy consumption. The model-free characteristic of RL avoids the disadvantage of implementing inaccurate or complex models for the environment, thereby enabling a great potential in the application of intelligent control for buildings.

  • 17.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    May, Ross
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wang, Xinru
    Pan, Song
    Yan, Da
    Jin, Yuan
    A novel reinforcement learning method for improving occupant comfort via window opening and closingManuskript (preprint) (Annet vitenskapelig)
  • 18.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    May, Ross
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wang, Xinru
    Pan, Song
    Yan, Da
    Jin, Yuan
    Xu, Liguo
    A review of reinforcement learning methodologies for controlling occupant comfort in buildings2019Inngår i: Sustainable cities and society, ISSN 2210-6707, Vol. 51, artikkel-id 101748Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Shah, Juveria
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Review of natural language processing techniques for characterizing positive energy districts2023Inngår i: journal of Physics; Conference series, Institute of Physics Publishing (IOPP), 2023, Vol. 2600, nr 8, artikkel-id 082024Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The concept of Positive Energy Districts (PEDs) has emerged as a crucial aspect of endeavours aimed at accelerating the transition to zero carbon emissions and climate-neutral living spaces. The focus of research has shifted from energy-efficient individual buildings to entire districts, where the objective is to achieve a positive energy balance over a specific timeframe. The consensus on the conceptualization of a PED has been evolving and a standardized checklist for identifying and evaluating its constituent elements needs to be addressed. This study aims to develop a methodology for characterizing PEDs by leveraging natural language processing (NLP) techniques to model, extract, and map these elements. Furthermore, a review of state-of-the-art research papers is conducted to ascertain their contribution to assessing the effectiveness of NLP models. The findings indicate that NLP holds significant potential in modelling the majority of the identified elements across various domains. To establish a systematic framework for AI modelling, it is crucial to adopt approaches that integrate established and innovative techniques for PED characterization. Such an approach would enable a comprehensive and effective implementation of NLP within the context of PEDs, facilitating the creation of sustainable and resilient urban environments. © 2023 Institute of Physics Publishing. All rights reserved.

  • 20.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Wang, Zhenwu
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    An Approach to Data Acquisition for Urban Building Energy Modeling Using a Gaussian Mixture Model and Expectation-Maximization Algorithm2021Inngår i: Buildings, E-ISSN 2075-5309, Vol. 11, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years, a building’s energy performance is becoming uncertain because of factors such as climate change, the Covid-19 pandemic, stochastic occupant behavior and inefficient building control systems. Sufficient measurement data is essential to predict and manage a building’s performance levels. Assessing energy performance of buildings at an urban scale requires even larger data samples in order to perform an accurate analysis at an aggregated level. However, data are not only expensive, but it can also be a real challenge for communities to acquire large amounts of real energy data. This is despite the fact that inadequate knowledge of a full population will lead to biased learning and the failure to establish a data pipeline. Thus, this paper proposes a Gaussian mixture model (GMM) with an Expectation-Maximization (EM) algorithm that will produce synthetic building energy data. This method is tested on real datasets. The results show that the parameter estimates from the model are stable and close to the true values. The bivariate model gives better performance in classification accuracy. Synthetic data points generated by the models show a consistent representation of the real data. The approach developed here can be useful for building simulations and optimizations with spatio-temporal mapping.

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  • 21.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Xu, Liguo
    May, Ross
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Pan, Song
    Wu, Jinshun
    A review of reinforcement learning methodologies on control systems for building energy2018Rapport (Annet vitenskapelig)
    Abstract [en]

    The usage of energy directly leads to a great amount of consumption of the non-renewable fossil resources. Exploiting fossil resources energy can influence both climate and health via ineluctable emissions. Raising awareness, choosing alternative energy and developing energy efficient equipment contributes to reducing the demand for fossil resources energy, but the implementation of them usually takes a long time. Since building energy amounts to around one-third of global energy consumption, and systems in buildings, e.g. HVAC, can be intervened by individual building management, advanced and reliable control techniques for buildings are expected to have a substantial contribution to reducing global energy consumptions. Among those control techniques, the model-free, data-driven reinforcement learning method seems distinctive and applicable. The success of the reinforcement learning method in many artificial intelligence applications has brought us an explicit indication of implementing the method on building energy control. Fruitful algorithms complement each other and guarantee the quality of the optimisation. As a central brain of smart building automation systems, the control technique directly affects the performance of buildings. However, the examination of previous works based on reinforcement learning methodologies are not available and, moreover, how the algorithms can be developed is still vague. Therefore, this paper briefly analyses the empirical applications from the methodology point of view and proposes the future research direction.

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  • 22.
    Han, Mengjie
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Zhao, Jing
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Shen, Jingchun
    Högskolan Dalarna, Institutionen för information och teknik, Byggteknik.
    Li, Yu
    The reinforcement learning method for occupant behavior in building control: A review2021Inngår i: Energy and Built Environment, ISSN 2666-1233, Vol. 2, nr 2, s. 137-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Occupant behavior in buildings has been considered the major source of uncertainty for assessing energy consumption and building performance. Modeling frameworks are usually built to accomplish a certain task, but the stochasticity of the occupant makes it difficult to apply that experience to a similar but distinct environment. For complex and dynamic environments, the development of smart devices and computing power makes intelligent control methods for occupant behaviors more viable. It is expected that they will make a substantial contribution to reducing global energy consumption. Among these control techniques, the reinforcement learning (RL) method seems distinctive and applicable. The success of the reinforcement learning method in many artificial intelligence applications has given an explicit indication of how this method might be used to model and adjust occupant behavior in building control. Fruitful algorithms complement each other and guarantee the quality of the optimization. However, the examination of occupant behavior based on reinforcement learning methodologies is not well established. The way that occupant interacts with the RL agent is still unclear. This study briefly reviews the empirical applications using reinforcement learning, how they have contributed to shaping the modeling paradigms and how they might suggest a future research direction.

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  • 23. Han, Y.
    et al.
    Wu, P.
    Geng, Z.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Editorial: Energy efficiency analysis and intelligent optimization of process industry2023Inngår i: Frontiers in Energy Research, E-ISSN 2296-598X, Vol. 11, artikkel-id 1283021Artikkel i tidsskrift (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 24. He, W.
    et al.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Solar Heating, Cooling and Power Generation — Current Profiles and Future Potentials2019Inngår i: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation / [ed] Xudong ZhaoXiaoli Ma, Springer, 2019, s. 31-78Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Due to the large amount of consumption of the fossil fuels, the ecological environment has suffered serious pollution and damage. Solar power technologies provide the best solution to the current energy and environment issues. In past decades, global solar thermal capacity increased rapidly, and now it has been used worldwide to provide heating, cooling and power generation. However, after years of development, solar energy utilization technology still faces problems such as low efficiency, high cost, difficulty in energy storage and unstable energy supply, which have been seriously restricting its applications. This chapter briefly summarizes the concept and classification of solar heating, cooling and power generation. Furthermore, some technology development and potential applications relating to solar heating, cooling and power generation are discussed.

  • 25. He, Wei
    et al.
    Hong, Xiaoqiang
    Zhao, Xudong
    Zhang, Xingxing
    University of Hull.
    Shen, Jinchun
    Ji, Jie
    Operational performance of a novel heat pump assisted solar facade loop-heat-pipe water heating system2015Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 146, s. 371-382Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper aims to present an investigation into the operational performance of a novel heat pump assisted solar façade loop-heat-pipe (LHP) water heating system using both theoretical and experimental methods. This involved (1) development of a computer numerical model; (2) simulation of the operational performance of the system by using the model; (3) test rig construction; and (4) dedicated experiment for verification of the model. It was found that the established model is able to predict the operational performance of the system at a reasonable accuracy. Analyses of the research results indicated that under the selected testing conditions, the average thermal efficiency of the LHP module was around 71%, much higher than that of the loop heat pipe without heat pump assistance. The thermal efficiency of the LHP module grew when the heat pump was turned-on and fell when the heat pump was turned-off. The water temperature remained a steadily growing trend throughout the heat pump turned-on period. Neglecting the heat loss of the water tank, the highest coefficient of the performance could reach up to 6.14 and its average value was around 4.93. In overall, the system is a new façade integrated, highly efficient and aesthetically appealing solar water heating configuration; wide deployment of the system will help reduce fossil fuel consumption in the building sector and carbon emission to the environment.

  • 26. He, Wei
    et al.
    Hong, Xiaoqiang
    Zhao, Xudong
    Zhang, Xingxing
    University of Hull.
    Shen, Jinchun
    Ji, Jie
    Theoretical investigation of the thermal performance of a novel solar loop-heat-pipe facade-based heat pump water heating system2014Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 77, s. 180-191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the paper was to present a dedicated theoretical investigation into the thermal performance of a novel solar loop-heat-pipe façade based heat pump water heating system. This involved thermo-fluid analyses, computer numerical model development, the model running up, modelling result analyses and conclusion. An energy balance network was established on each part and the whole range of the system to address the associated energy conversion and transfer processes. On basis of this, a computer numerical model was developed and run up to predict the thermal performance of such a system at different system configurations, layouts and operational conditions. It was suggested that the loop heat pipes could be filled with either water, R134a, R22 or R600a; of which R600a is the favourite working fluid owing to its relatively larger heat transfer capacity and positive pressure in operation. Variations in the system configuration, i.e., glazing covers, heat exchangers, would lead to identifiable differences in the thermal performance of the system, represented by the thermal efficiency and COP. Furthermore, impact of the external operational parameters, i.e., solar radiation and ambient air temperature, to the system's thermal performance was also investigated. The research was based on an innovative loop-heat-pipe façade and came up with useful results reflecting the thermal performance of the combined system between the façade and heat pump. This would help promote development and market penetration of such an innovative solar heating technology, and thus contribute to achieving the global targets in energy saving and carbon emission reduction.

  • 27. He, Wei
    et al.
    Zhang, Gan
    Zhang, Xingxing
    University of Nottingham.
    Ji, Jie
    Li, Guiqiang
    Zhao, Xudong
    Recent development and application of thermoelectric generator and cooler2015Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 143, s. 1-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Energy crisis and environment deterioration are two major problems for 21st century. Thermoelectric device is a promising solution for those two problems. This review begins with the basic concepts of the thermoelectric and discusses its recent material researches about the figure of merit. It also reports the recent applications of the thermoelectric generator, including the structure optimization which significantly affects the thermoelectric generator, the low temperature recovery, the heat resource and its application area. Then it reports the recent application of the thermoelectric cooler including the thermoelectric model and its application area. It ends with the discussion of the further research direction.

  • 28. Hedman, Åsa
    et al.
    Rehman, Hassam U.
    Gabaldón, Andrea
    Bisello, Adriano
    Albert-Seifried, Vicky
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Guarino, Francesco
    Grynning, Steinar
    Eicker, Ursula
    Reda, Francesco
    IEA EBC Annex83 Positive Energy Districts2021Inngår i: Buildings, E-ISSN 2075-5309, Vol. 11, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    At a global level, the need for energy efficiency and an increased share of renewable energy sources is evident, as is the crucial role of cities due to the rapid urbanization rate. As a consequence of this, the research work related to Positive Energy Districts (PED) has accelerated in recent years. A common shared definition, as well as technological approaches or methodological issues related to PEDs are still unclear in this development and a global scientific discussion is needed. The International Energy Agency’s Energy in Buildings and Communities Programme (IEA EBC) Annex 83 is the main platform for this international scientific debate and research. This paper describes the challenges of PEDs and the issues that are open for discussions and how the Annex 83 is planned and organized to facilitate this and to actively steer the development of PEDs major leaps forward. The main topics of discussion in the PED context are the role and importance of definitions of PEDs, virtual and geographical boundaries in PEDs, the role of different stakeholders, evaluation approaches, and the learnings of realized PED projects.

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  • 29. Hu, J
    et al.
    Chen, W
    Yin, Y
    Li, Y
    Yang, D
    Wang, H
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Electrical-thermal-mechanical properties of multifunctional OPV-ETFE foils for transparent membrane buildings2018Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 66, s. 394-402Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ETFE (ethylene tetrafluoroethylene) foils integrated organic photovoltaic cells (OPV) have attracted considerable attention in recent years due to the achievement of sustainability. As building materials, multifunctional OPV-ETFE foils could produce electricity, store thermal energy and possess structural capability. In this case, electrical, thermal and mechanical properties coexist and influence each other due to photovoltaic/thermal effects. Understanding the fundamental mechanism is significant to analyze and design corresponding structures. This paper concerns coupled properties of OPV-ETFE specimens with controlled experiments. One-parameter and two-parameter analysis of two typical specimens are performed to investigate essential properties. Experimental observations show that within normal working conditions, electrical properties are relatively independent but that thermal-mechanical properties are related to each other. Yield stress, yield strain and elastic modulus are calculated from stress-strain curves; these mechanical properties are comparable with those of original ETFE foils at the same temperature. It is concluded from temperature-stress curves that yield point has a critical effect on temperature-stress correlation and that mechanical properties of double OPV specimens are better than those of single OPV specimens. Generally, these mechanical properties could provide basic insights into evaluation of energetic performance and structural behavior of transparent membrane buildings.

  • 30.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Copertaro, Benedetta
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Shen, Jingchun
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Löfgren, Isabelle
    Rönnelid, Mats
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Fahlen, Jan
    Andersson, Dan
    Svanfeldt, Mikael
    A review of data centers as prosumers in district energy systems: Renewable energy integration and waste heat reuse for district heating2020Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 258, artikkel-id 114109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As large energy prosumers in district energy systems, on the one hand, data centers consume a large amount of electricity to ensure the Information Technologies (IT) facilities, ancillary power supply and cooling systems work properly; on the other hand, data centers produce a large quantity of waste heat due to the high heat dissipation rates of the IT facilities. To date, a systematic review of data centers from the perspective of energy prosumers, which considers both integration of the upstream green energy supply and downstream waste heat reuse, is still lacking. As a result, the potentials for improving data centers’ performances are limited due to a lack of global optimization of the upstream renewable energy integration and downstream waste heat utilization. This study is intended to fill in this gap and provides such a review. In this regard, the advancements in different cooling techniques, integration of renewable energy and advanced controls, waste heat utilization and connections for district heating, real projects, performance metrics and economic, energy and environmental analyses are reviewed. Based on the enormous amount of research on data centers in district energy systems, it has been found that: (1) global controls, which can manage the upstream renewable production, data centers’ operation and waste heat generation and downstream waste heat utilization are still lacking; (2) regional climate studies represent an effective way to find the optimal integration of renewable energy and waste heat recovery technologies for improving the data centers’ energy efficiency; (3) the development of global energy metrics will help to appropriately quantify the data center performances.

  • 31.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik. City University of Hong Kong.
    Fan, C
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wang, J
    A hierarchical coordinated demand response control for buildings with improved performances at building group2019Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 242, s. 684-694Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Demand response control is one of the common means used for building peak demand limiting. Most of the existing demand response controls focused on single building’s performance optimization, and thus may cause new undesirable peak demands at building group, imposing stress on the grid power balance and limiting the economic savings. A few latest studies have demonstrated the potential benefits of demand response coordination, but the proposed methods cannot be applied in large scales. The main reason is that, for demand response coordination of multiple buildings, associated computational load and coordination complexity, increasing exponentially with building number, are challenges to be solved. This study, therefore, proposes a hierarchical demand response control to optimize operations of a large scale of buildings for group-level peak demand reduction. The hierarchical control first considers the building group as a ‘virtual’ building and searches the optimal performance that can be achieved at building group using genetic algorithm. To realize such optimal performance, it then coordinates each single building’s operation using non-linear programming. For validations, the proposed method has been applied on a case building group, and the study results show that the hierarchical control can overcome the challenges of excessive computational load and complexity. Moreover, in comparison with conventional independent control, it can achieve better performances in aspects of peak demand reduction and economic savings. This study provides a coordinated control for application in large scales, which can improve the effectiveness and efficiency in relieving the grid stress, and reduce the end-users’ electricity bills.

  • 32.
    Huang, Pei
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Han, Mengjie
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Hussain, Sayed Asad
    The University of British Columbia, Canada.
    Jayprakash Bhagat, Rohit
    Hogarehalli Kumar, Deepu
    Characterization and optimization of energy sharing performances in energy-sharing communities in Sweden, Canada and Germany2022Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 326, artikkel-id 120044Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Peer-to-peer (P2P) renewable power sharing within a building community is a promising solution to enhance the community's self-sufficiency and relieve the grid stress posed by the increased deployment of distributed renewable power. Existing studies have pointed out that the energy sharing potentials of a building community are affected by various factors including location, community scale, renewable energy system (RES) capacity, energy system type, storage integration, etc. However, the impacts of these factors on the energy sharing potentials in a building community are not fully studied. Being unaware of those factors’ impacts could lead to reduced energy sharing potentials and thus limit the associated improvement in energy and economic performances. Thus, this study conducts a comprehensive analysis of various factors’ impacts on the energy sharing performances in building communities. Two performance indicators are first proposed to quantify the energy sharing performances: total amount of energy sharing and energy sharing ratio (ESR). Then, parametric studies are conducted based on real electricity demand data in three countries to reveal how these factors affect the proposed indictors and improvements in self-sufficiency, electricity costs, and energy exchanges with the power grid. Next, a genetic algorithm based design method is developed to optimize the influential parameters to maximize the energy sharing potentials in a community. The study results show that the main influential factors are RES capacity ratio, PV capacity ratio, and energy storage system capacity. A large energy storage capacity can enhance the ESR. To achieve the maximized ESR, the optimal RES capacity ratio should be around 0.4 ∼ 1.1. The maximum energy sharing ratio is usually smaller in high latitude districts such as Sweden. This study characterizes the energy sharing performances and provides a novel perspective to optimize the design of energy systems in energy sharing communities. It can pave the way for the large integration of distributed renewable power in the future. © 2022 The Author(s)

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  • 33.
    Huang, Pei
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Lovati, M.
    Shen, Jingchun
    Högskolan Dalarna, Institutionen för information och teknik, Byggteknik.
    Chai, J.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Investigation of the Peer-to-Peer energy trading performances in a local community under the future climate change scenario in Sweden2022Inngår i: Energy Reports, E-ISSN 2352-4847, Vol. 8, s. 989-1001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Peer-to-peer (P2P) energy sharing among neighboring households is a promising solution to mitigating the difficulties of renewable power (such as solar Photovoltaics (PV)) penetration on the power grid. Until now, there is still a lack of study on the impacts of future climate change on the P2P energy trading performances. The future climate change will cause variances in the renewable energy production and further lead to changes in the economic performances of households with various energy uses and affect the decision making in PV ownership and pricing strategies. Being unaware of these impacts could potentially hinder the P2P energy sharing application in practice. To bridge such knowledge gap, this paper conducts a systematic investigation of the climate change impacts on the energy sharing performance in solar PV power shared communities. The future weather data is generated using the Morphine method, and an agent-based modeling method is used for simulating the energy trading behaviors of households. Four comparative scenarios of different PV ownerships and pricing strategies are designed. The detailed energy trading performances (including the PV power self-sufficiency, cost saving, revenues, and compound annual growth rate) for the four comparative scenarios are analyzed under both the present and future climates and compared. The study results of a building community located in Sweden show that the future climate change is more beneficial to large energy use households while less beneficial to small households. High price of energy trading can improve the fairness of the economic performances in the community, especially when some of the households do not have any PV ownership. This study can help understand the future climate impacts on the energy sharing performances of building communities, which can in turn guide decision making in PV ownership and price setting for different households under the future climate change to facilitate real applications. © 2021 The Author(s)

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  • 34.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Lovati, Marco
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Bales, Chris
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    A coordinated control to improve performance for a building cluster with energy storage, electric vehicles, and energy sharing considered2020Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 268, artikkel-id 114983Artikkel i tidsskrift (Fagfellevurdert)
  • 35.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Lovati, Marco
    EURAC Research, Bolzano, Italy; University of Trento, Trento, Italy.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Bales, Chris
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Hallbeck, Sven
    NIBE Climate Solutions, Sweden.
    Becker, Anders
    Ferroamp Elektronik AB, Spånga, Sweden.
    Bergqvist, Henrik
    LudvikaHem AB Bobutiken, Ludvika, Sweden.
    Hedberg, Jan
    LudvikaHem AB Bobutiken, Ludvika, Sweden.
    Maturi, Laura
    EURAC Research, Bolzano, Italy.
    Transforming a residential building cluster into electricity prosumers in Sweden: Optimal design of a coupled PV-heat pump-thermal storage-electric vehicle system2019Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 255, artikkel-id 113864Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Smart grid is triggering the transformation of traditional electricity consumers into electricity prosumers. This paper reports a case study of transforming an existing residential cluster in Sweden into electricity prosumers. The main energy concepts include (1) click-and-go photovoltaics (PV) panels for building integration, (2) centralized exhaust air heat pump, (3) thermal energy storage for storing excess PV electricity by using heat pump, and (4) PV electricity sharing within the building cluster for thermal/electrical demand (including electric vehicles load) on a direct-current micro grid. For the coupled PV-heat pump-thermal storage-electric vehicle system, a fitness function based on genetic algorithm is established to optimize the capacity and positions of PV modules at cluster level, with the purpose of maximizing the self-consumed electricity under a non-negative net present value during the economic lifetime. Different techno-economic key performance indicators, including the optimal PV capacity, self-sufficiency, self-consumption and levelized cost of electricity, are analysed under impacts of thermal storage integration, electric vehicle penetration and electricity sharing possibility. Results indicate that the coupled system can effectively improve the district-level PV electricity self-consumption rate to about 77% in the baseline case. The research results reveal how electric vehicle penetrations, thermal storage, and energy sharing affect PV system sizing/positions and the performance indicators, and thus help promote the PV deployment. This study also demonstrates the feasibility for transferring the existing Swedish building clusters into smart electricity prosumers with higher self-consumption and energy efficiency and more intelligence, which benefits achieving the ‘32% share of renewable energy source’ target in EU by 2030.

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  • 36.
    Huang, Pei
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Munkhammar, J.
    Fachrizal, R.
    Lovati, M.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Sun, Y.
    Comparative studies of EV fleet smart charging approaches for demand response in solar-powered building communities2022Inngår i: Sustainable cities and society, ISSN 2210-6707, Vol. 85, artikkel-id 104094Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of electric vehicles (EVs) has been on the rise during the past decade, and the number is expected to rapidly increase in the future. At aggregated level, the large EV charging loads, if not well regulated, will cause great stress on the existing grid infrastructures. On the other hand, considered as a resource-efficient and cost-effective demand response resource, EV fleet smart charging control methods have been developed and applied to mitigate power issues of the grid while avoiding expensive upgrade of power grid infrastructure. Until now, there is no systematic study on how different coordination mechanisms affecting the EV fleet's charging demand response performance. Thus, it is still unclear which one may perform better in the increasingly common solar-powered building communities, especially as demand response is increasingly concerned. Aiming to fill in such knowledge gaps, this study conducted systematic comparative studies of three representative control methods selected from the non-coordinated, bottom-up coordinated, and top-down coordinated control categories. Their power regulation performances have been comparatively investigated in two perspectives: minimizing peak power exchanges with the grid and maximizing PV self-utilization, based on a real building community in Sweden. Meanwhile, their computational performances have also been investigated. The study results show that due to the ability to schedule and coordinate all the EVs simultaneously, the top-down coordinated control is superior to the other two control methods in the considered demand response performances. Note that its better performance is realized with a higher computational load, leading to possible convergence difficulties in practice. The study results will help improve understanding of how coordination affect the EV smart charging control performances. It will pave the way for developments of more sophisticated control methods for EV smart charging in more complex scenarios. © 2022 Elsevier Ltd

  • 37.
    Huang, Pei
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Sun, Yongjun
    Lovati, Marco
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Solar-photovoltaic-power-sharing-based design optimization of distributed energy storage systems for performance improvements2021Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 222, artikkel-id 119931Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 38.
    Huang, Pei
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Tu, Ran
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Han, Mengjie
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    Sun, Yongjun
    Hussain, Syed Asad
    Zhang, Linfeng
    Investigation of electric vehicle smart charging characteristics on the power regulation performance in solar powered building communities and battery degradation in Sweden2022Inngår i: Journal of Energy Storage, ISSN 2352-152X, E-ISSN 2352-1538, Vol. 56, s. 105907-105907, artikkel-id 105907Artikkel i tidsskrift (Fagfellevurdert)
  • 39.
    Huang, Pei
    et al.
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    A systematic comparison of various electric vehicle charging approaches2022Inngår i: E3S Web of Conferences, EDP Sciences , 2022, Vol. 362, artikkel-id 06006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of electric vehicles (EVs) has been on the rise. Most of the existing EV smart charging controls can be categorized into three approaches according to their optimization principles: individual, bottom-up and top-down. Until now, systematic comparison and analysis of the different approaches are still lacking. It is still unknown whether a control approach performs better than others and, if yes, why is it so. This study aims to fill in such knowledge gaps by conducting a systematic comparison of these three different control approaches and analyzing their performances in depth. A representative control algorithm will be selected from each control approach, then the selected algorithms will be applied for optimizing EV charging loads in a building community in Sweden. Their power regulation performances will be comparatively investigated. This study will help pave the way for the developments of more sophisticated control algorithms for EV smart charging. © 2022 The Authors, published by EDP Sciences.

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  • 40.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Bales, Chris
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Persson, Tomas
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    A coordinated control to improve energy performance for a building cluster with energy storage, EVs, and energy sharing2020Inngår i: International Conference Organised by IBPSA-Nordic, 13th–14th October 2020, OsloMet. BuildSIM-Nordic 2020. Selected paper, SINTEF Academic Press , 2020, s. 98-105Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Existing studies have developed some advanced controls for energy storage system charging/discharging in a building cluster (enabling PV power sharing among different buildings), which can effectively improve the aggregated performances. However, in the existing controls, the flexible demand shifting ability of electric vehicles (EVs) are rarely considered, leading to limited performance improvements at building cluster level. Thus, this study proposes a coordinated control of building cluster with both energy sharing and the EV charging considered, with the purpose of improving the cluster-level performance. The simulation results show that in a typical summer week in Sweden, the developed control can increase the cluster-level daily renewable selfconsumption by 40% and meanwhile reduce the electricity bills by as much as 20% compared with conventional controls for a summer week in Ludvika, Sweden

  • 41.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Copertaro, Benedetta
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Saini, Puneet
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Yan, Da
    Wu, Yi
    Chen, Xiangjie
    A Technical Review of Modeling Techniques for Urban Solar Mobility: Solar to Buildings, Vehicles,and Storage (S2BVS)2020Inngår i: Sustainability: Science, Practice, & Policy, E-ISSN 1548-7733, Vol. 12, artikkel-id 7035Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 42.
    Huang, Pei
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Löfgren, Isabelle
    Rönnelid, Mats
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Fahlén, Jan
    EcoDC.
    Andersson, Dan
    EcoDC.
    Svanfeldt, Michael
    EcoDC.
    Datacenters as prosumers in urban energy system: a review2019Inngår i: Proceedings of 11th International Conference on Applied Energy, Part 3, 2019, Vol. 3, artikkel-id 368Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    As a large energy prosumer in the urban energy systems, on the one hand, datacenters consume a large amount of electricity to ensure the IT facilities and ancillary power supply and cooling systems work properly; on the other hand, datacenters produce a large amount of waste heat due to the high heat dissipation rates of the IT facilities. To date, a systematic review of datacenters from the perspective of energy prosumers, which considers both integration of the upstream green energy supply and downstream waste heat reuse, is still lacking. This study fills in this gap and provides such a review. By providing a full picture of datacenters in the urban energy systems, this study aims to search new opportunities for improving datacenter overall energy efficiency and reducing carbon emissions.

    Fulltekst (pdf)
    fulltext
  • 43. Jin, Y.
    et al.
    Yan, D.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Han, Mengjie
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Kang, X.
    An, J.
    Sun, H.
    District household electricity consumption pattern analysis based on auto-encoder algorithm2019Inngår i: IOP Conference Series: Materials Science and Engineering, 2019, Vol. 609, nr 7, artikkel-id 072028Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The energy shortage is one key issue for sustainable development, a potential solution of which is the integration with the renewable energy resources. However, the temporal sequential characteristic of renewable resources is different from traditional power grid. For the entire power grid, it is essential to match the energy generation side with the energy consumption side, so the load characteristic at the energy use side is crucial for renewable power integration. Better understanding of energy consumption pattern in buildings contributes to matching different source of energy generation. Under the background of integration of traditional and renewable energy, this research focuses on analysis of different household electricity consumption patterns in an urban scale. The original data is from measurement of daily energy consumption with smart meter in households. To avoid the dimension explosion phenomenon, the auto-encoder algorithm is introduced during the clustering analysis of daily electricity use data, which plays the role of principal component analysis. The clustering based on auto-encoder gives a clear insight into the urban electricity use patterns in household. During the data analysis, several feature variables are proposed, which include peak value, valley value and average value. The distinction analysis is also conducted to evaluate the analysis performance. The study takes households in Nanjing city, China as a case study, to conduct the clustering analysis on electricity consumption of residential buildings. The analysis results can be further applied, such as during the capacity design of district energy storage.

    Fulltekst (pdf)
    fulltext
  • 44. Jin, Yuan
    et al.
    Yan, Da
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    An, Jingjing
    Han, Mengjie
    Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys.
    A data-driven model predictive control for lighting system based on historical occupancy in an office building: Methodology development2021Inngår i: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 14, s. 219-235Artikkel i tidsskrift (Fagfellevurdert)
  • 45. Koke, Johannes
    et al.
    Schippmann, André
    Shen, Jingchun
    Högskolan Dalarna, Institutionen för information och teknik, Byggteknik.
    Zhang, Xingxing
    Högskolan Dalarna, Institutionen för information och teknik, Energiteknik.
    Kaufmann, Peter
    Krause, Stefan
    Strategies of Design Concepts and Energy Systems for NearlyZero‐Energy Container Buildings (NZECBs) inDifferent Climates2021Inngår i: Buildings, E-ISSN 2075-5309, Vol. 11, nr 8, artikkel-id 364Artikkel i tidsskrift (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 46. Lei, S.
    et al.
    Shi, Y.
    Yan, Y.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Numerical study on inertial effects on liquid-vapor flow using lattice Boltzmann method2019Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 160, s. 428-435Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liquid-vapor flow in porous media is studied in this article. To fulfill this goal, a double-distribution-function lattice Boltzmann (LB) model is proposed based on the separate-phase governing equations at the representative elementary volume (REV) scale. Importantly, besides the Darcy force and capillary force, which were commonly included in previous studies, the LB model in this article also considers the inertial force characterized by the Forchheimer term. This feature enables the model to offer an effective description of liquid-vapor flow in porous media at low, intermediate and even high flow rates. We validated the LB model by simulating a single-phase flow in porous media driven by a pressure difference and found its results are in good agreement with the available analytical solutions. We then applied the model to study water-vapor flow in a semi-infinite porous region bounded by an impermeable and heated wall. The numerical simulation reveals the flow and mass transfer characteristics under the compounding effects of inertial, Darcy and capillary forces. Through a comparison with the results given by the generalized Darcy's law, our numerical results directly evidence that the inertial force is a dominating factor when a fluid passes through porous media at an intermediate or high flow rate.

    Fulltekst (pdf)
    fulltext
  • 47. Li, G.
    et al.
    Tang, L.
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Dong, J.
    Xiao, M.
    Factors affecting greenhouse microclimate and its regulating techniques: a review2018Inngår i: IOP Conference Series: Earth and Environmental Science, 2018, Vol. 167, nr 1, artikkel-id 012019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper reviews factors affecting greenhouse microclimate and its regulating techniques towards upgrading the greenhouse applications in the area of southeast China which have little or very basic technology integration. The microclimate of greenhouse is apparently influenced by the shape and its orientation, the wind direction, the property of covering material, and the use of insect-proof screen as they eventually affect the total solar radiation, the thermal characterises, and the flow pattern inside. The natural ventilation and sun block are the most common method to cool the greenhouse, but more efficient evaporative cooling such as pad-fan system, misting/fogging system and roof sprinkler are required with extreme temperatures. The earth to air heat exchanger and the heat storage using phase change material may be used for heating or cooling throughout the year which are more economic and energy-saving than other traditional thermal technologies. The reviewed knowledge provides insights into upgrading greenhouse applications in Ningbo area towards more sustainable and efficient greenhouse farming.

    Fulltekst (pdf)
    fulltext
  • 48. Li, G
    et al.
    Tang, L
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Hao, J
    Xiao, M
    Dong, J
    Numerical and experimental investigations on improving the efficiency of Clean-In-Place procedures in closed processing systems: A review2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper reviews the recent numerical and experimental investigations on improving the efficiency of Clean-In-Place procedures thus saving operation energy. The paper covers the fouling of equipment surfaces, the concept of CIP and its operation practices, the physical factors controlling the efficiency of CIP procedures with a special attention being paid to the hydrodynamic force of the cleaning fluids. The studies show that CIP efficiency dependents on many factors, such as the type of soil to be removed, the cleaning time, the temperature of cleaning agent, and the favourable hydrodynamic force of the moving liquid. Among the hydrodynamic factors, the wall shear stress and its fluctuation rate reported to be the dominating factor for cleaning straight circular pipes. Whilst for cleaning of more complex geometries and areas difficult to clean, the controlling factor may also include the flow pattern, flow exchange, flow turbulence, and the property of the recirculation zone.

  • 49. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Dong, Jie
    A review of factors affecting the efficiency of clean-in-place procedures in closed processing systems2019Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 178, s. 57-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reviews the current state of researches on improvement of Clean-In-Place (CIP) procedures in closed processing system thus saving energy, with a special attention paid to the hydrodynamic effects of cleaning fluid and the numerical and experimental approaches to investigate the identified controlling factors. The paper discussed the fouling problems of processing plants and the importance of sufficient CIP procedures, the forces contributing to cleaning with a special focus on the hydrodynamic effects. In general, it is possible to enhance hydrodynamic removal forces by local introduction of, among others, high wall shear stress and fluctuation rate of wall shear stress without consuming more energy. A theoretical model of particle removal in flow was also reviewed which supports the factors identified. The paper therefore further reviewed and compared the current state of modelling and experimental techniques on CIP improvement. To simulation the CIP process, it is necessary to consider 3D time-resolved Large Eddy Simulation with a Hybrid RANS-LES WMLES as Sub-Grid-Scale model because it captures both the mean and fluctuation rate of flow variables, while affordable for industrial flows. The wall shear stress measurement techniques and cleanablity test methods were also discussed and suggested.

  • 50. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Xiao, Manxuan
    Dong, Jie
    Effect of solar radiation and natural ventilation on temperature distribution in a greenhouse: a numerical study2017Konferansepaper (Fagfellevurdert)
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