| 1. |
- Dai, B., et al.
(författare)
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Evaluation of transcritical CO 2 heat pump system integrated with mechanical subcooling by utilizing energy, exergy and economic methodologies for residential heating
- 2019
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Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 192, s. 202-220
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Tidskriftsartikel (refereegranskat)abstract
- A transcritical CO 2 heat pump (HP) system for residential space heating integrated with direct dedicated mechanical subcooling (DMS) is proposed, and mathematical models are developed to study the annual energetic and economic performances considering the influence of frosting. The operation characteristics by adopting different heating terminals used in five typical cities are also assessed. The results show a maximum coefficient of performance (COP) is achieved at the optimum discharge pressure and subcooling degree. The COP is promoted by 24.4% and the discharge pressure is decreased by 2.093 MPa at the ambient temperature of −10 °C and water supply/return temperature of 45/40 °C. The seasonal performance factor (SPF) is enhanced more noticeably for severe cold region. For the case of Harbin using floor-coil radiator (FCR) or normal fan-coil unit (N-FCU) as heating terminal, SPF is improved by 32.0%. The highest SPF is achieved when small temperature difference fan-coil unit (STD-FCU) is employed. The exergy efficiency can also be apparently improved, especially for the cities located in severe cold region and using FCR or N-FCU as heating terminal due to the reduction in throttling loss of CO 2 system. The purchased equipment cost and electricity cost of the CO 2 HP with DMS are both lower than those of traditional CO 2 heat pump system. The CO 2 HP DMS system using STD-FCU as heating terminal shows superior economical efficiency to traditional system, with levelized annual total cost reduced by 7.51–15.27%.
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| 2. |
- Chen, Z., et al.
(författare)
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Using existing infrastructures of high-speed railways for photovoltaic electricity generation
- 2022
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Ingår i: Resources, Conservation and Recycling. - : Elsevier B.V.. - 0921-3449 .- 1879-0658. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- Cities worldwide are stepping up efforts to reshape their infrastructure to ensure a carbon-neutral and sustainable future, leading to the rapid electrification of transportation systems. The electricity demand of this sector, particularly that of high-speed railways, is increasing. Application of the existing infrastructures of railway stations and available land along rail lines for photovoltaic (PV) electricity generation has the potential to power high-speed bullet trains with renewable energy and supply surplus electricity to surrounding users. In this work, a methodology based on a geographic information system was established to evaluate the PV potential along rail lines and on the roofs of train stations. The Beijing-Shanghai high-speed railway (HSR) was used as a case study. Its total PV potential reached 5.65 GW (of which the station potential accounted for 264 MW, approximately 4.68%, of the total potential), with a lifelong generation capacity of 155 TWh, which corresponds to approximately 12% of the total new installed capacity of China in 2020. Although electricity prices and solar resources differed along the railway line, all PV systems were profitable. Moreover, a comparison between the electricity consumption and generation shows that the PV+HSR system can cover most of the electricity demand of the Beijing-Shanghai HSR without a storage system. This concept can be further expanded to other rail lines and stations. Within the context of global carbon peaks and carbon neutrality, the integration of PV and railway systems should be promoted.
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| 3. |
- Hao, D., et al.
(författare)
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Solar energy harvesting technologies for PV self-powered applications : A comprehensive review
- 2022
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Ingår i: Renewable energy. - : Elsevier Ltd. - 0960-1481 .- 1879-0682. ; 188, s. 678-697
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Tidskriftsartikel (refereegranskat)abstract
- Many key aspects of society, such as transport, housing and health care, have been significantly improved by the advent of a range of electricity applications, and the power generation for electricity applications has been a major field of research. Photovoltaic (PV) self-powered technologies are promising technologies for addressing applications' power supply challenges and alleviating conventional electricity load and environmental pollution. This study reviews solar energy harvesting (SEH) technologies for PV self-powered applications. First, the PV power generation and scenarios of PV self-powered applications are analyzed. Second, analysis of system design for PV self-powered applications is presented. Third, key components for PV self-powered applications, including maximum power point tracking (MPPT) techniques and power management (PM) systems are discussed in detail. Furthermore, numerous PV self-powered applications and utilizations of energy harvesting are summarized. Finally, some recommendations are proposed for further research.
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| 4. |
- Jiang, M., et al.
(författare)
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National level assessment of using existing airport infrastructures for photovoltaic deployment
- 2021
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 298
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Tidskriftsartikel (refereegranskat)abstract
- The airport is one of the most fundamental infrastructures in our society, its terminal buildings and parking lots are ideal locations for photovoltaic (PV) installation. The future trend of the electrification of the aviation and automobile industries will increase the electricity demand at airports calls for the integration of PV systems with airport infrastructure. Understanding the benefits of airport PV systems is crucial for the stakeholders including investors, project developers and policymakers to promote PV sector development. Thus, evaluation of the PV potential and relevant economic performance of airports is essential. Combined with the geographic information system (GIS), the PV potential of the civil airports in China is investigated. The results show that potential PV capacity of China's 239 civil airports reaches up to 2.50 GW. The annual electricity demand of the aviation industry in 8 provinces can be self-satisfied via airport PV generation. Detailed economic analysis shows that all airport PV systems are profitable through appropriate investment and operation strategies. © 2021
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