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Sökning: WFRF:(Wang Chen) > Mälardalens universitet

  • Resultat 1-10 av 33
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2.
  • Chen, Haoqian, et al. (författare)
  • Towards renewable public transport : Mining the performance of electric buses using solar-radiation as an auxiliary power source
  • 2022
  • Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 325
  • Tidskriftsartikel (refereegranskat)abstract
    • Transforming the road public transport to run on renewable energy is vital solution to achieve carbon neutral and net zero goals. This paper evaluates the potential of using solar radiation-generated electricity as an auxiliary power supplementary for the battery of electric buses, based on a developed framework that using publicly street-view panoramas, GPS trajectory data and DEM data as input parameters of solar radiation model. A case study of Qingdao, China with 547 bus routes, 28,661 street-view panoramas shows that the solar-radiation electricity generated at noon during the operation accounts for about one-fifth, one-eighth of the total elec-tricity consumption of a bus traveling one kilometer in a sunny day and a cloudy day, respectively. Spatial variability shows significant solar-radiation power generation advantages in newly-launched areas and expressway. The solar power generated in a sunny day can make a bus half of passengers and with air conditioner off at least one extra trip in 2:1 replacement schedule, and nearly close to one extra trip in 4:3 replacement schedule. A correlated relation between the solar-radiation power generation benefit and the operation schedule of electric buses is observed, implying that the high cost of 2:1 replacement schedule for long-distance routes during summer or winter can be reduced. The proposed framework can help us evaluate and understand the feasibility of solar radiation-generated electricity energy of electric bus fleets covering the large-scale urban areas at different times, locations, and weather conditions, so as to support effective decisions at better planning of PV-integrated electric buses.
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3.
  • Liu, Junwei, et al. (författare)
  • Polymer synergy for efficient hole transport in solar cells and photodetectors
  • 2023
  • Ingår i: Energy & Environmental Science. - : ROYAL SOC CHEMISTRY. - 1754-5692 .- 1754-5706.
  • Tidskriftsartikel (refereegranskat)abstract
    • Hole transport materials (HTMs) have greatly advanced the progress of solution-based electronic devices in the past few years. Nevertheless, most devices employing dopant-free organic HTMs can only deliver inferior performance. In this work, we introduced a novel "polymer synergy" strategy to develop versatile dopant-free polymer HTMs for quantum dot/perovskite solar cells and photodetectors. With this synergy strategy, the optical, electrical and aggregation properties of polymer HTMs can be modulated, resulting in complementary absorption, high hole mobility, favorable energy landscape and moderate aggregation. Moreover, a clear orientational transition was observed for the developed HTMs with a 9-fold increase in the face-on/edge-on ratio, providing a highway-like carrier transport for electronic devices, as revealed by in situ characterization and ultrafast transient absorption. With these benefits, the photovoltaic and photodetection performance of quantum dot devices were boosted from 11.8% to 13.5% and from 2.95 x 10(12) to 3.41 x 10(13) Jones (over a 10-fold increase), respectively. Furthermore, the developed polymer HTMs can also significantly enhance the photovoltaic and photodetection performance of perovskite devices from 15.1% to 22.7% and from 2.7 x 10(12) to 2.17 x 10(13)Jones with the same device structure, indicating their great application potential in the emerging optoelectronics.
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4.
  • Liu, Yong, et al. (författare)
  • One-Pot Catalytic Conversion of Raw Lignocellulosic Biomass into Gasoline Alkanes and Chemicals over LiTaMoO6 and Ru/C in Aqueous Phosphoric Acid
  • 2015
  • Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 3:8, s. 1745-1755
  • Tidskriftsartikel (refereegranskat)abstract
    • Lignocellulosic biomass is a renewable feedstock that has the potential to replace the diminishing fossil fuels. Herein, we reported the simultaneous conversion of cellulose, hemicellulose and lignin from raw biomass into gasoline alkanes (hexanes and pentanes) and monophenols and related hydrocarbons over layered LiTaMoO6 and Ru/C in aqueous phosphoric acid medium. Specifically, gasoline alkanes were directly yielded from the carbohydrate components, based on hemicellulose and cellulose, and the total yield could be up to 82.4%. Notably, the lignin fraction could also be transformed into monophenols, related alcohols and hydrocarbons by the one-pot reaction. It suggested that the hydrocracking of monophenol fraction could be performed in this catalytic system. The total yield of volatile products was 53% based on the lignin fraction. In this paper, the influences of phosphoric acid concentration, substrate ash and the amino acids derived from the biogenic impurities were investigated and different raw biomass substrates were tested. Furthermore, the catalysts could be reused for several runs to convert raw biomass without pretreatment.
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5.
  • Liu, Z., et al. (författare)
  • Solar harvest : Enhancing carbon sequestration and energy efficiency in solar greenhouses with PVT and GSHP systems
  • 2023
  • Ingår i: Renewable energy. - : Elsevier Ltd. - 0960-1481 .- 1879-0682. ; 211, s. 112-125
  • Tidskriftsartikel (refereegranskat)abstract
    • It is universally acknowledged that climate change brings widespread attention to solar greenhouse plant carbon sequestration. Suitable technologies in solar greenhouses were, are, and will be play a leading role in this vital transition. The primary aim of this research is to examine the energy efficiency and carbon sequestration potential of a solar-assisted ground-source heat pump (SAGSHP) heating system. This hybrid system, which integrates a horizontal ground-source heat pump (GSHP) system with PVT and heat storage, can efficiently fulfill the heating demands of a greenhouse and function as a positive energy building. Four plants include cucumber, tomato, cowpea, and lettuce were selected to compare the carbon absorption effects. Results show that the hybrid system outperforms conventional systems, with a coefficient of performance (COP) of 6.71 during peak hours and PVT efficiency over 57.88%, which effectively meet the heat load of the greenhouse and keep the indoor heat comfortable. In addition, for the carbon sequestration potential of four plants, tomato exhibited the highest photosynthetic carbon sequestration of 3522 kgCO2·m−2. Cowpea showed the strongest daily carbon sequestration capacity at 26.86 gCO2m−2d−1 and better economic income. Through the application of this enhanced solar greenhouse, people can enhance the utilization of solar energy, establish flexible interaction between energy and information flow, and make a promising option for sustainable building design. 
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6.
  • Zhang, Kai, et al. (författare)
  • Power generation assessment of photovoltaic noise barriers across 52 major Chinese cities
  • 2024
  • Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 361
  • Tidskriftsartikel (refereegranskat)abstract
    • Photovoltaic noise barriers (PVNBs) have the potential to contribute to sustainable urban development by increasing the supply of renewable energy to cities while decreasing traffic noise pollution. However, estimating the power generation of PVNBs at the city or national scale remains a challenge due to the complexities of the urban environment and the difficulties associated with collecting data on road noise barriers (RNBs) and radiation. This study used RNBs, 2.5-dimensional (2.5D) buildings, and hourly time resolution radiation data, to estimate the power generation of PVNBs in 52 of China's major cities. First, hourly building shadows were estimated for each day of the year, covering the period from sunrise to sunset, to identify areas of RNB that are shaded at any given time. Second, hourly clear-sky radiation data were collected and corrected using a radiation correction model to simulate real weather radiation. Finally, utilizing an inclined surface radiation estimation model, the photovoltaic (PV) potential both inside and outside RNBs affected by building shadows was assessed. Subsequently, the power generation of PVNB was estimated based on parameters of mainstream PV systems in the market. The results show that the RNB mileage in 52 selected cities represents 87.7% of China's total RNB mileage. Building shadows often result in a radiation loss of approximately 30% for RNBs reception. The installed capacity and annual power generation of PVNBs in all investigated cities are 2.04 GW and 690.74 GWh, respectively. This study estimates the comprehensive PV potential of potentially exploitable PVNBs in China, offering essential scientific insights to inform and facilitate the strategic development of PVNB projects at both the national and municipal levels.
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7.
  • Chen, Chang, et al. (författare)
  • Feasibility of using thermal inertia to shift the peak energy demand of buildings
  • 2018
  • Ingår i: International Heat Transfer Conference. - Connecticut : Begell House Inc.. ; , s. 4419-4424
  • Konferensbidrag (refereegranskat)abstract
    • Peak load introduces stress to the grid as supplied electricity is inadequate during peak demand period. In order to relieve the stress of grid and ensure the electricity supply, peak load shifting is an effective option. Buildings are consuming a huge amount of energy for space heating, ventilation and cooling. Using building thermal inertia to shift peak load has attracted more and more attention. By using thermal inertia, heat supplied during off-peak periods can be stored in the construction materials, and used in peak demand hours. However, peak shaving shall not sacrifice the indoor thermal comfort. The objective of this work is to investigate the impact of demand shifting by using thermal inertia on the indoor temperature. In order to understand how the demand shifting impacts the thermal comfort. A CFD model is developed to simulate an office room in winter time. Three cases that represent different shifting strategies are studied. According the results, when increasing the heating temperature, using thermal inertia of buildings can shift peak load, guarantee indoor thermal comfort and save energy. © 2018 International Heat Transfer Conference. All rights reserved.
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8.
  • Chen, S., et al. (författare)
  • Operational flexibility of active distribution networks with the potential from data centers
  • 2021
  • Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 293
  • Tidskriftsartikel (refereegranskat)abstract
    • With the development of information technology, the scale and quantity of internet data centers (IDCs) are expanding rapidly. IDCs have emerged as the major electricity consumers in active distribution networks (ADNs), which dramatically increase the electricity load and have a significant impact on the operational flexibility of ADNs. Geographically distributed IDCs can participate in the operation of ADNs with the potential for spatio-temporal load regulation. This paper proposes flexible dispatch strategies of data centers to improve the operational flexibility of ADNs. First, a data-power model of IT equipment is proposed based on piecewise linearization to describe the power consumption characteristics of data centers. The flexible dispatch strategies for the delay-tolerant workload are further proposed from two aspects of temporal transfer and spatial allocation. Then, considering the potential for spatio-temporal load regulation, the operational flexibility analysis model with data centers is formulated to adapt to the operational requirements of ADNs in complex environments. Case studies show that through the spatio-temporal regulation of workload, the energy efficiency of IDCs can be effectively improved. The flexible dispatch of IDCs can also reduce the voltage violation and feeder load imbalance of ADNs, which can facilitate providing the high-quality power supply for IDCs.
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9.
  • Chen, Y., et al. (författare)
  • Theory-guided hard constraint projection (HCP) : A knowledge-based data-driven scientific machine learning method
  • 2021
  • Ingår i: Journal of Computational Physics. - : Academic Press Inc.. - 0021-9991 .- 1090-2716. ; 445
  • Tidskriftsartikel (refereegranskat)abstract
    • Machine learning models have been successfully used in many scientific and engineering fields. However, it remains difficult for a model to simultaneously utilize domain knowledge and experimental observation data. The application of knowledge-based symbolic artificial intelligence (AI) represented by expert systems is limited by the expressive ability of the model, and data-driven connectionism AI represented by neural networks is prone to produce predictions that might violate physical principles. In order to fully integrate domain knowledge with observations and make full use of the strong fitting ability of neural networks, this study proposes theory-guided hard constraint projection (HCP). This deep learning model converts physical constraints, such as governing equations, into a form that is easy to handle through discretization, and then implements hard constraint optimization through projection in a patch. Based on rigorous mathematical proofs, theory-guided HCP can ensure that model predictions strictly conform to physical mechanisms in the constraint patch. The training process of theory-guided HCP only needs a small amount of labeled data (sparse observation), and it can supervise the model by combining the coordinates (label-free data) with domain knowledge. The performance of the theory-guided HCP is verified by experiments based on a published heterogeneous subsurface flow problem. The experiments show that theory-guided HCP requires fewer data, and achieves higher prediction accuracy and stronger robustness to noisy observations, than the fully connected neural networks and soft constraint models. Furthermore, due to the application of domain knowledge, theory-guided HCP possesses the ability to extrapolate and can accurately predict points outside of the range of the training dataset.
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10.
  • Ji, H., et al. (författare)
  • Robust operation for minimizing power consumption of data centers with flexible substation integration
  • 2022
  • Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 248
  • Tidskriftsartikel (refereegranskat)abstract
    • The rapid development of digital economy has led to a dramatic increasement of internet data centers (IDCs), which consume a large amount of electricity. The diverse data-processing demands, high power consumption and workload uncertainty put forward a high requirement for the economical and secure operation of IDCs. As information technology (IT) devices are driven by direct current (DC), flexible substation (FS) has been gradually utilized to provide DC power for IDCs. This paper proposes robust operation strategies for minimizing IDC power consumption with FS integration. First, the linearized IDC power consumption model based on the technology of dynamic voltage and frequency scaling (DVFS) is proposed to describe the operating state of IT devices. Then, considering the FS-based coordinated operation of IDC, photovoltaic (PV) station and energy storage system (ESS), the deterministic power consumption minimization model of IDCs is established. Considering the workload uncertainty, the operation strategies based on distributionally robust optimization (DRO) for IDCs are further proposed. Finally, the effectiveness of proposed method is validated on a modified practical network with IDCs integrated. Results show that through the dispatch of workload and power flow regulation of FS, the power consumption and dropping workload of IDCs are effectively reduced. 
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  • Resultat 1-10 av 33

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