| 1. |
- Sun, Q., et al.
(författare)
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A Comprehensive Review of Smart Energy Meters in Intelligent Energy Networks
- 2016
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Ingår i: IEEE Internet of Things Journal. - 2327-4662. ; 3:4, s. 464-479
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Tidskriftsartikel (refereegranskat)abstract
- The significant increase in energy consumption and the rapid development of renewable energy, such as solar power and wind power, have brought huge challenges to energy security and the environment, which, in the meantime, stimulate the development of energy networks toward a more intelligent direction. Smart meters are the most fundamental components in the intelligent energy networks (IENs). In addition to measuring energy flows, smart energy meters can exchange the information on energy consumption and the status of energy networks between utility companies and consumers. Furthermore, smart energy meters can also be used to monitor and control home appliances and other devices according to the individual consumer's instruction. This paper systematically reviews the development and deployment of smart energy meters, including smart electricity meters, smart heat meters, and smart gas meters. By examining various functions and applications of smart energy meters, as well as associated benefits and costs, this paper provides insights and guidelines regarding the future development of smart meters.
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| 2. |
- Bai, Q., et al.
(författare)
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Experimental investigation on the solidification behavior of phase change materials in open-cell metal foams
- 2017
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Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; , s. 3703-3708
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Konferensbidrag (refereegranskat)abstract
- This study presented an experimental investigation on solidification behavior of fluid saturated in highly porous open-cell copper foams. Particular attention has been made on the effect of pore parameters (pore density and porosity) on the solidification behavior. A purposely-designed apparatus was built for experimental observations. Results showed that the copper foam had a great effect on solidification and the full solidification time can be saved up to 50%, especially preventing the decrease in solidification rate during the later stage of phase change. The smaller the porosity is, the faster the solidification rate will be. Pore density was found to have little influence upon the solidification rate. In addition, the local natural convection does exist but it has a slight effect on solidification, leading to the slant of the solid-liquid interface.
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| 3. |
- Bai, Q., et al.
(författare)
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Experimental investigation on the solidification rate of water in open-cell metal foam with copper fins
- 2018
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Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; , s. 210-214
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Konferensbidrag (refereegranskat)abstract
- This study focused on the effect of inserting fins into metal foam on the solidification rate. To this aim, a well-designed experimental system with solid-liquid interface visualization was built. Metal foam samples with different fin intervals were prepared for experiments. Solidification process of water saturating in finned metal foam under bottom cooling was experimentally investigated. Results showed that inserting fins into metal foam can make a promotional improvement on solidification rate of water. The solid-liquid interface became curved after inserting fins, compared with metal foam sample without fins. Besides, changing the interval has little effect on the solidification rate.
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| 4. |
- Guo, S., et al.
(författare)
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Mobilized thermal energy storage : Materials, containers and economic evaluation
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 177, s. 315-329
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Tidskriftsartikel (refereegranskat)abstract
- The transportation of thermal energy is essential for users who are located far away from heat sources. The networks connecting them achieve the goal in efficient heat delivery and reasonable cost, especially for the users with large heat demands. However, it is difficult to satisfy the heat supply of the detached or emergent users with the existing pipelines. Therefore, a promising alternative, called mobilized thermal energy storage (M-TES), was proposed to deliver the heat flexibly without the restriction of networks. In this paper, a review of studies on M-TES is conducted in terms of materials, containers and economic evaluation. The potential candidates of materials, such as sugar alcohols, hydrated salts, alkalies and zeolite are reviewed and compared based on their thermophysical properties, price, advantages and disadvantages. Various containers, including the shell-and-tube, encapsulated, direct-contact, detachable and sorptive types, are discussed from the aspects of configuration, performance and utilization. Furthermore, the studies on the economic evaluation of M-TES systems are summarized and discussed based on the analysis of the economic indicators, including initial cost, operating cost, revenue, subsidy and energy cost. Finally, the challenges and future perspectives for developing M-TES are presented.
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| 5. |
- Ma, Z., et al.
(författare)
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Deep Neural Network-based Impacts Analysis of Multimodal Factors on Heat Demand Prediction
- 2020
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Ingår i: IEEE Transactions on Big Data. - : IEEE. - 2372-2096 .- 2332-7790. ; 6:3, s. 594-605
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Tidskriftsartikel (refereegranskat)abstract
- Prediction of heat demand using artificial neural networks has attracted enormous research attention. Weather conditions, such as direct solar irradiance and wind speed, have been identified as key parameters affecting heat demand. This paper employs an Elman neural network to investigate the impacts of direct solar irradiance and wind speed on the heat demand from the perspective of the entire district heating network. Results of the overall mean absolute percentage error (MAPE) show that direct solar irradiance and wind speed have quite similar impacts. However, the involvement of direct solar irradiance can clearly reduce the maximum absolute deviation when only involving direct solar irradiance and wind speed, respectively. In addition, the simultaneous involvement of both wind speed and direct solar irradiance does not show an obvious improvement of MAPE. Moreover, the prediction accuracy can also be affected by other factors like data discontinuity and outliers.
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| 6. |
- Ma, Z., et al.
(författare)
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The role of data analysis in the development of intelligent energy networks
- 2017
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Ingår i: IEEE Network. - : Institute of Electrical and Electronics Engineers Inc.. - 0890-8044 .- 1558-156X. ; 31:5, s. 88-95
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Tidskriftsartikel (refereegranskat)abstract
- Data analysis plays an important role in the development of intelligent energy networks (IENs). This article reviews and discusses the application of data analysis methods for energy big data. The installation of smart energy meters has provided a huge volume of data at different time resolutions, suggesting data analysis is required for clustering, demand forecasting, energy generation optimization, energy pricing, monitoring and diagnostics. The currently adopted data analysis technologies for IENs include pattern recognition, machine learning, data mining, statistics methods, and so on. However, existing methods for data analysis cannot fully meet the requirements for processing the big data produced by IENs, therefore more comprehensive data analysis methods are needed to handle the increasing amount of data and to mine more valuable information.
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| 7. |
- Qiu, R., et al.
(författare)
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Roadmap to urban energy internet with wind electricity-natural gas nexus : Economic and environmental analysis
- 2022
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 245
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Tidskriftsartikel (refereegranskat)abstract
- Electrolysis hydrogen generation technology is one of the feasible ways to alleviate the problem of wind electricity curtailment. One promising hydrogen value-added application is to blend hydrogen into the natural gas grid and sell it as the heat energy carrier. This paper aims to discuss the feasibility of a roadmap to urban energy internet with wind electricity-natural gas nexus. Firstly, a framework is raised to integrate wind electricity generation, electrolysis hydrogen generation, and hydrogen-natural gas blending systems. Secondly, a series of reasonable hydrogen supply profiles are provided based on annual electricity curtailment and realistic natural gas scheduling. Then, an energy optimisation model and a techno-economic model are applied to simulate the generation of electricity and hydrogen, as well as determine the most economical hydrogen supply scheme. Finally, a case study in the Beijing-Tianjin-Hebei region of China is taken to validate the benefits of the proposed roadmap. The preferred scheme is worked out with the net present value of 88.8 M$, including the economy configurations of the electricity-hydrogen hybrid generation system, as well as the hydrogen-natural gas blending plan. The results also indicate that annual electricity curtailment and annual carbon emission are decreased by 204 GWh (48.8%) and 40.2 kt (49.9%).
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| 8. |
- Xie, J., et al.
(författare)
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SEA : A Combined Model for Heat Demand Prediction
- 2018
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Ingår i: Proceedings of 2018 6th IEEE International Conference on Network Infrastructure and Digital Content, IC-NIDC 2018. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538660669 ; , s. 71-75
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Konferensbidrag (refereegranskat)abstract
- Heat demand prediction is a prominent research topic in the area of intelligent energy networks. It has been well recognized that periodicity is one of the important characteristics of heat demand. Seasonal-trend decomposition based on LOESS (STL) algorithm can analyze the periodicity of a heat demand series, and decompose the series into seasonal and trend components. Then, predicting the seasonal and trend components respectively, and combining their predictions together as the heat demand prediction is a possible way to predict heat demand. In this paper, STL-ENN-ARIMA (SEA), a combined model, was proposed based on the combination of the Elman neural network (ENN) and the autoregressive integrated moving average (ARIMA) model, which are commonly applied to heat demand prediction. ENN and ARIMA are used to predict seasonal and trend components, respectively. Experimental results demonstrate that the proposed SEA model has a promising performance.
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| 9. |
- Yang, Xiaohu, et al.
(författare)
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Comparison of direct numerical simulation with volume-averaged method on composite phase change materials for thermal energy storage
- 2018
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 229, s. 700-714
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Tidskriftsartikel (refereegranskat)abstract
- Melting heat transfer in open-cell metal foams embedded in phase-change materials (PCMS) predicted by the volume-averaged method (VAM) was systematically compared with that calculated using direct numerical simulation (DNS), with particular attention placed upon the contribution of natural convection in the melt region to overall phase change heat transfer. The two-temperature model based on the assumption of local thermal non-equilibrium was employed to account for the large difference of thermal conductivity between metallic ligaments and PCM (paraffin). The Forchheimer extended Darcy model was employed to describe the additional flow resistance induced by metal foam. For the DNS, a geometric model of metal foam based on tetrakaidehedron cells was reconstructed. The DNS results demonstrated significant temperature difference between ligament surface and PCM, thus confirming the feasibility of local thermal non-equilibrium employed in VAM simulations. Relative to the DNS results, the VAM combined with the two-temperature model could satisfactorily predict transient solid-liquid interface evolution and local temperature distribution, although pore-scale features of phase change were lost. The presence of natural convection affected significantly the melting front shape, temperature distribution and full melting. The contribution of natural convection to overall phase change heat transfer should be qualitatively and quantitatively given sufficient consideration from both macroscopic (VAM) and microscopic (DNS) point of views. Besides, practical significance and economic prospective using metal foam in TES unit for WHR system to provide residential heating or hot water is discussed and analyzed.
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| 10. |
- Yang, X., et al.
(författare)
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Role of pin fin-metal foam composite structure in improving solidification : Performance evaluation
- 2020
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Ingår i: International Communications in Heat and Mass Transfer. - : Elsevier Ltd. - 0735-1933 .- 1879-0178. ; 117
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Tidskriftsartikel (refereegranskat)abstract
- Cold storage technology in air conditioning systems makes an important contribution to shifting peak load of electricity. How to break through the limitation of low thermal conductivity for cold storage medium so as to improve the energy charging/discharging efficiency is predominantly concerned. An experimental and numerical study on the solidification of phase change material (PCM) saturated in a novel pin fin-foam composite was carried out. Particular concerns were placed on the mass distribution of pin fins and metal foam for a given copper mass towards maximizing the solidification rate. To address this issue, a three-dimensional numerical model was built and verified by comparing with experimental measurements on solidification front evolution and temperatures at both PCM and fins. The variations in phase interface evaluation, solidification fraction, temperature field, and the cold storage capacity during ice storage were analyzed. Results demonstrated that the fin-foam composite outperformed the competing structures of metal foam or pin fin, favoring a significant improvement in PCM solidification. A 40% fins and 60% metal foam combination was recommended towards maximizing solidification rate for engineering applications. When the target solidification fraction was 90% for operation, the fin-foam cold storage tank had the longest investment payback period and the largest 20-year total profit among the four structures among the four cases (pure PCM, pin fin, metal foam, and fin-foam composite).
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