| 1. |
- Geng, Y., et al.
(författare)
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Recent trend of industrial emissions in developing countries
- 2016
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 166, s. 187-190
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Tidskriftsartikel (refereegranskat)abstract
- Greenhouse gas (GHG) emissions from industrial sectors are increasing, particularly in the developing world where pursuing industrialization has been highly addressed. This calls for further studies to learn and share experiences for developing countries. In order to fill in such a research gap, this special issue focuses on examining the recent trend of industrial emissions in developing countries. Among the manuscripts submitted to the Special Issue, twelve papers have been accepted after review, covering assessment indicators, tools and methods, and policies. Key industrial sectors, including cement, lime, aluminum, coal, mining, glass, soda ash, etc, have been investigated. Valuable policy insights have been raised, including wide scale upgrading, replacement and deployment of best available technologies, integrated information platforms, cross-cutting technologies and measures, a shift to low carbon electricity, radical product innovations, carbon dioxide capture and storage (CCS), demand on new and replacement products, systematic approaches and collaboration among different industries. These useful suggestions could be shared or learned by industrial policy makers or managers in the developing world so that the overall GHG emissions from their industrial sectors can be mitigated by considering the local realities.
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| 2. |
- Shao, S., et al.
(författare)
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Enlarging Regional Disparities in Energy Intensity within China
- 2020
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Ingår i: Earth's Future. - : John Wiley and Sons Inc. - 2328-4277. ; 8:8
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Tidskriftsartikel (refereegranskat)abstract
- As energy saving and emission reduction become a global action, the disparity in energy intensity between different regions is a new rising problem that stems a country's or region's energy-saving potential. Here we collect China's provincial panel data (1995–2017) of primary and final energy consumption to evaluate China's unequal and polarized regional pattern in energy intensity, decompose the inequality index into contributing components, and investigate possible driving factors behind the unequal pattern both regionally and structurally, for the first time. The results show that China's interprovince disparities in energy intensity increase and are exacerbated by the enlarging disparities in energy intensity between the least developed and most developed regions of China. The causes for this phenomenon are as follows: (i) rather loose regulatory measures on mitigating coal consumption; (ii) inferior energy processing technology in areas specializing in energy-intensive industries; (iii) increasing interregional energy fluxes embodied in trade; and (iv) separate jurisdictions at provincial administrative levels. These factors can synthetically result in unintended spillover to areas with inferior green technologies, suggesting an increasingly uneven distribution of energy-intensive and carbon-intensive industries and usage of clean energy. The results reveal the necessities of regional coordination and cooperation to achieve a green economy. ©2020. The Authors. Earth's Future published by Wiley Periodicals LLC on behalf of American Geophysical Union
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| 3. |
- Tian, Ruijie, et al.
(författare)
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Study on the promotion of natural gas-fired electricity with energy market reform in China using a dynamic game-theoretic model
- 2017
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 185, s. 1832-1839
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Tidskriftsartikel (refereegranskat)abstract
- Natural gas-fired electricity (NGFE) has gained great attention in China recently. However, the high generation cost leads to the NGFE cannot compete economically with the coal-fired electricity (CFE) when the value of peak power and positive environment externality of NGEF are not considered. Therefore, the market reform of natural gas (NG), including price deregulation, carbon tax and environmental subsidy are of vital importance to promote the penetration of NGFE. In the present study, a dynamic game-theoretic model was developed to analyze the impacts of market reforming for natural gas on the promotion effect of NGFE, in which the hourly real-time pricing (RTP) was applied in both natural gas and electricity markets. Five scenarios were proposed with different policy combinations of pricing mechanism reform, carbon tax and environmental subsidy. Based on the analysis results, it can be concluded that (i) deregulating the NG price, imposing carbon tax and adopting environment subsidy can promote the market penetration of NGFE greatly; and (ii) the market deregulation can increases the share of NGFE to 5.49%, and imposing the carbon tax of 100RMB/tonne CO2 can raise it further to 7.66%, furthermore if the environmental subsidy of 134.3 RMB/MWh is also included, the share of NGFE can reach 15%.
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| 4. |
- Zhang, Z., et al.
(författare)
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Carbon mitigation potential afforded by rooftop photovoltaic in China
- 2023
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Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Rooftop photovoltaics (RPVs) are crucial in achieving energy transition and climate goals, especially in cities with high building density and substantial energy consumption. Estimating RPV carbon mitigation potential at the city level of an entire large country is challenging given difficulties in assessing rooftop area. Here, using multi-source heterogeneous geospatial data and machine learning regression, we identify a total of 65,962 km2 rooftop area in 2020 for 354 Chinese cities, which represents 4 billion tons of carbon mitigation under ideal assumptions. Considering urban land expansion and power mix transformation, the potential remains at 3-4 billion tons in 2030, when China plans to reach its carbon peak. However, most cities have exploited less than 1% of their potential. We provide analysis of geographical endowment to better support future practice. Our study provides critical insights for targeted RPV development in China and can serve as a foundation for similar work in other countries.
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| 5. |
- Chen, Chang, et al.
(författare)
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Feasibility of using thermal inertia to shift the peak energy demand of buildings
- 2018
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Ingår i: International Heat Transfer Conference. - Connecticut : Begell House Inc.. ; , s. 4419-4424
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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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| 6. |
- Chen, Y., et al.
(författare)
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Colored and patterned silicon photovoltaic modules through highly transparent pearlescent pigments
- 2024
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier B.V.. - 0927-0248 .- 1879-3398. ; 275
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Tidskriftsartikel (refereegranskat)abstract
- Building-integrated photovoltaic (BIPV) is crucial for emission reduction and energy transition in urban areas. However, the limited aesthetic appearance hinders the popularization of BIPV as traditional photovoltaic (PV) modules are usually black and dark blue, therefore, colorization of PV modules can solve the problem and pave the way for the further development of BIPV. In this study, some high-efficiency colored crystalline silicon (c-Si) PV modules prepared by screen printing the front glass with pearlescent pigments are developed. A suitable pigment for the colorization of PV modules, namely the synthetic mica-based interference pearlescent pigment, was finalized by analyzing the interference theories and comparing present and potential pigments. An adjusted coloring layer thickness from 15.50 μm to 57.17 μm was then realized, which contributed to a variable lightness (L*) from 39.3 to 46.9. Besides, a series of PV modules with various colors used for building facades that could retain 93.71 % of original power generation ability, were produced for different design choices. Moreover, 15 cm × 15 cm bicolor patterned PV modules with a precise motif were fabricated, which can achieve a satisfying power conversion efficiency (PCE) of 18.64 %, only a 5.44 % relative reduction of power generation ability compared with the reference PV module (PCE = 19.71 %). The colorization method for single-colored and patterned PV modules not only guarantees power generation ability but also provides an aesthetic appearance for BIPV applications.
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| 7. |
- Chen, Y., et al.
(författare)
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Theory-guided hard constraint projection (HCP) : A knowledge-based data-driven scientific machine learning method
- 2021
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Ingår i: Journal of Computational Physics. - : Academic Press Inc.. - 0021-9991 .- 1090-2716. ; 445
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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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| 8. |
- Li, X., et al.
(författare)
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Performance comparison regarding loop heat pipes with different evaporator structures
- 2019
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Ingår i: International journal of thermal sciences. - : Elsevier Masson SAS. - 1290-0729 .- 1778-4166. ; 136, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- The design of evaporator can clearly affect the performance of loop heat pipes (LHPs). In order to understand the influence, three different designs of evaporators were compared, including embedding vapor channels on the heating surface (Config_1), embedding vapor channels in the wick (Config_2), and separating the wick from the heating surface (Config_3). Based on the validated model, the operating temperature, the start-up time, and the transport distance, as key performance indicators, were studied. Results show that, to improve the performance of LHP, it is of importance to reduce the contacting area between the wick and the heating surface. Due to the existence of the steam chamber, the wick was separated from the heating surface in Config_3, resulting in the lowest operating temperature and the shortest start-up time. The pressure head of evaporation is also an important component of the driving force. For Config_3, since the evaporation happened in the steam chamber rather than in the wick, it had a longer transport distance than Config_1 and Config_2 at the same heat load.
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| 9. |
- Liu, S., et al.
(författare)
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Thermodynamic analysis of CO2 transcritical two-stage compression refrigeration cycle systems with expanders
- 2017
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Ingår i: HKIE Transactions Hong Kong Institution of Engineers. - : Taylor and Francis Asia Pacific. - 1023-697X. ; 24:2, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- The key to improving the efficiency of carbon dioxide (CO2) transcritical refrigeration systems is to select an appropriate two-stage compression system. In this study, the thermodynamic performance of six different CO2 transcritical two-stage refrigeration systems with expanders is compared. The design parameters are analysed to determine their respective impacts on the system coefficient of performance (COP) in order to ascertain which system configuration produces the maximum system COP. It is concluded that the system with a two-stage expander and incomplete intercooling has great advantages in terms of performance and equipment selection for the high-pressure stage in certain circumstances. Under the given conditions, the design parameters including the evaporating temperature, the condensing temperature, the compressor efficiency of the high-pressure stage, and the compressor efficiency of the low-pressure stage impact on the system performance. It should be noted that the gas cooler outlet temperature and the compressor efficiency of the low-pressure stage are the major factors which affect the efficiency of the system; thus, the system design and equipment selection should minimise the gas cooler outlet temperature and select a high-efficiency compressor for the low-pressure stage to ensure efficient and safe operation.
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| 10. |
- Liu, Z., et al.
(författare)
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Power to heat : Opportunity of flexibility services provided by building energy systems
- 2023
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Ingår i: Advances in Applied Energy. - : Elsevier Ltd. - 2666-7924. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Buildings play a crucial role in global electricity consumption, but their function is evolving. Rather than merely consuming energy, buildings have the potential to become energy producers through participating in flexibility services, which involve demand response and distributed energy supplies. However, the new technological and societal challenges that arise from temporal and spatial changes on both supply and demand sides make building services increasingly complex. This paper presents an opportunity for flexibility services offered by building energy systems via power-to-heat technology and discusses four key aspects: quantitative indicators based on thermal inertia, model predictive control for building flexibility, flexible system optimization for smart buildings, and applications of flexible services. Thermal inertia is a crucial factor that transcends technical constraints and serves as a bridge between the demand and supply sides. Demand-side response and data-driven cogeneration under model predictive control are essential for managing building flexibility. In addition, flexible system optimization is achieved through the combination of demand-side trading and disturbed system optimization. Applications of flexible services represent a combination of demand-side trading and disturbed system optimization in the fields of engineering and sociology. Finally, the paper explores the challenges, as well as the potential and models of building flexibility services technologies, including features that can facilitate automated operational decision-making on both the demand and supply sides.
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