A computational fluid dynamics （CFD） model is carried out to describe the wire-plate electrostatic precipitator （ESP） in high temperature conditions, aiming to study the effects of high temperature on the electro-...A computational fluid dynamics （CFD） model is carried out to describe the wire-plate electrostatic precipitator （ESP） in high temperature conditions, aiming to study the effects of high temperature on the electro- hydrodynamic （EHD） characteristics. In the model, the complex interactions at high temperatures between the electric field, fluid dynamics and the particulate flow are taken into account. We apply different numerical methods for different fields, including an electric field model, Euler-Lagrange particle-laden flows model, and particle charging model. The effects of high temperature on ionic wind, EHD characteristics and collection effi- ciency are investigated. The numerical results show high temperature causes more significant effects of the ionic wind on the gas secondary flow. High viscosity of gas at high temperature makes particles follow the gas flow pattern more closely. High temperature reduces the surface electric strength, so that the mean electric strength weakens the space charging. On the contrary, there is an increase in the diffusion charging at high tem- perature compared with at low temperature. High temperature increases the ratio of mean drag force over mean electrostatic force actin~ on the ~atticles which mav contribute to a decline of collection efficiencv.展开更多
The charging of electric vehicles(EVs) impacts the distribution grid, and its cost depends on the price of electricity when charging. An aggregator that is responsible for a large fleet of EVs can use a market-based c...The charging of electric vehicles(EVs) impacts the distribution grid, and its cost depends on the price of electricity when charging. An aggregator that is responsible for a large fleet of EVs can use a market-based control algorithm to coordinate the charging of these vehicles, in order to minimize the costs. In such an optimization, the operational parameters of the distribution grid, to which the EVs are connected, are not considered. This can lead to violations of the technical constraints of the grid(e.g., undervoltage, phase unbalances); for example, because many vehicles start charging simultaneously when the price is low. An optimization that simultaneously takes the economic and technical aspects into account is complex, because it has to combine time-driven control at the market level with eventdriven control at the operational level. Diff erent case studies investigate under which circumstances the market-based control, which coordinates EV charging, conflicts with the operational constraints of the distribution grid. Especially in weak grids, phase unbalance and voltage issues arise with a high share of EVs. A low-level voltage droop controller at the charging point of the EV can be used to avoid many grid constraint violations, by reducing the charge power if the local voltage is too low. While this action implies a deviation from the cost-optimal operating point, it is shown that this has a very limited impact on the business case of an aggregator, and is able to comply with the technical distribution grid constraints, even in weak distribution grids with many EVs.展开更多
Building-integrated photovoltaic(BIPV) is an important application way of solar photovoltaic power. The electric vehicle(EV) charging and parking shed of BIPV is the regeneration energy intellectual integration demons...Building-integrated photovoltaic(BIPV) is an important application way of solar photovoltaic power. The electric vehicle(EV) charging and parking shed of BIPV is the regeneration energy intellectual integration demonstration application system collection of photovoltaic(PV) grid power,PV off- grid power,EV charging and parking shed,and any part of the functions and their combination will be engaged in practical application on demand. The paper describes the PV shed system structure and design in detail with the present of its actual photos. The shed is 50 m long and 5.5 m wide and capable of parking 18 cars. Under the control of system intellectual controller,the power produced by PV from sunlight will charge the parking EV car prior to charging the storage battery,charging the storage battery prior to grid power,grid power at last,and charge the EV by utility grid when it is a cloudy or rainy day.展开更多
We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition bet...We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition between the ferromagnetic interaction of Fe3+and Fe5+ions and the antiferromagnetic one of Fe3+and Fe3+ions results in a unidirectional anisotropy in the cluster-glass system.An antiferromagnetically interfacial exchange coupling constant Ji1.95 meV at the cluster-glass region was yielded by fitting the cooling field-dependence of the exchange bias field.展开更多
基金Supported by the National Natural Science Foundation of China(51176170,51390490,51125025)the Natural Science Foundation of Zhejiang Province(LR12E06001)partially supported by the Fundamental Research Funds for the Central Universities
文摘A computational fluid dynamics （CFD） model is carried out to describe the wire-plate electrostatic precipitator （ESP） in high temperature conditions, aiming to study the effects of high temperature on the electro- hydrodynamic （EHD） characteristics. In the model, the complex interactions at high temperatures between the electric field, fluid dynamics and the particulate flow are taken into account. We apply different numerical methods for different fields, including an electric field model, Euler-Lagrange particle-laden flows model, and particle charging model. The effects of high temperature on ionic wind, EHD characteristics and collection effi- ciency are investigated. The numerical results show high temperature causes more significant effects of the ionic wind on the gas secondary flow. High viscosity of gas at high temperature makes particles follow the gas flow pattern more closely. High temperature reduces the surface electric strength, so that the mean electric strength weakens the space charging. On the contrary, there is an increase in the diffusion charging at high tem- perature compared with at low temperature. High temperature increases the ratio of mean drag force over mean electrostatic force actin~ on the ~atticles which mav contribute to a decline of collection efficiencv.
基金supported in part by the European Commission through the project P2P-Smartest:Peer to Peer Smart Energy Distribution Networks (H2020-LCE-2014-3,project 646469)
文摘The charging of electric vehicles(EVs) impacts the distribution grid, and its cost depends on the price of electricity when charging. An aggregator that is responsible for a large fleet of EVs can use a market-based control algorithm to coordinate the charging of these vehicles, in order to minimize the costs. In such an optimization, the operational parameters of the distribution grid, to which the EVs are connected, are not considered. This can lead to violations of the technical constraints of the grid(e.g., undervoltage, phase unbalances); for example, because many vehicles start charging simultaneously when the price is low. An optimization that simultaneously takes the economic and technical aspects into account is complex, because it has to combine time-driven control at the market level with eventdriven control at the operational level. Diff erent case studies investigate under which circumstances the market-based control, which coordinates EV charging, conflicts with the operational constraints of the distribution grid. Especially in weak grids, phase unbalance and voltage issues arise with a high share of EVs. A low-level voltage droop controller at the charging point of the EV can be used to avoid many grid constraint violations, by reducing the charge power if the local voltage is too low. While this action implies a deviation from the cost-optimal operating point, it is shown that this has a very limited impact on the business case of an aggregator, and is able to comply with the technical distribution grid constraints, even in weak distribution grids with many EVs.
基金China Southern Power Grid New Energy Experimental Project(No.03HC0901578)
文摘Building-integrated photovoltaic(BIPV) is an important application way of solar photovoltaic power. The electric vehicle(EV) charging and parking shed of BIPV is the regeneration energy intellectual integration demonstration application system collection of photovoltaic(PV) grid power,PV off- grid power,EV charging and parking shed,and any part of the functions and their combination will be engaged in practical application on demand. The paper describes the PV shed system structure and design in detail with the present of its actual photos. The shed is 50 m long and 5.5 m wide and capable of parking 18 cars. Under the control of system intellectual controller,the power produced by PV from sunlight will charge the parking EV car prior to charging the storage battery,charging the storage battery prior to grid power,grid power at last,and charge the EV by utility grid when it is a cloudy or rainy day.
基金supported by the National Basic Research Program of Chinathe National Natural Sciences Foundation of China(Grant No.11205015)+1 种基金the Natural Sciences Foundation of Beijing(Grant No.1113017)Beijing Area Logistics System&Technology Major Laboratory and the Logistics Management and Engineering Innovation Platform of Beijing Wuzi University
文摘We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition between the ferromagnetic interaction of Fe3+and Fe5+ions and the antiferromagnetic one of Fe3+and Fe3+ions results in a unidirectional anisotropy in the cluster-glass system.An antiferromagnetically interfacial exchange coupling constant Ji1.95 meV at the cluster-glass region was yielded by fitting the cooling field-dependence of the exchange bias field.
