On March 31, in accordance with the typical design requirements of the State Grid, the f irst large electric vehicle (EV) charging station, built by the North China Grid,
The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is propo...The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is proposed in this study,i.e.a half separated-half coupled cathode(HSHC)flow field which has two inlets but just one outlet.A 3D numerical PEMFC model is applied to study the effect of the HSHC flow field on PEMFC performance and its operating strategy in terms of operating conditions.The study results are shown as follows:Compared with the two conventional cathode flow fields,the HSHC flow field improves the water balance along the channel and increases the current density by 17.1%at a cathode stoichiometry of 3.25.It is because the HSHC flow field can overcome the water loss at channels upstream and the water accumulation at channels downstream.The draw water phenomenon(DWP)in the HSHC flow field is observed,which is mainly affected by the water vapor pressure of channel.Based on the DWP,cooling channel inlet flow rates can be used to adjust water balance,but severe water loss should be avoided.In addition,the inlet temperature control in HSHC flow field should be that cell temperature>cathode channel inlet temperature>cooling channel inlet temperature>ambient temperatures for better water balance.展开更多
In this paper,combined with the relevant speed theory and characteristics of the law,the current highway speed transition design problems are studied and analyzed.In the process of specific analysis,mainly combined wi...In this paper,combined with the relevant speed theory and characteristics of the law,the current highway speed transition design problems are studied and analyzed.In the process of specific analysis,mainly combined with the characteristics of different types of highway speed changes and road section design requirements,this paper studies and analyzes the design methods of different types of highway speed transition section.And on this basis,according to the design principles and requirements of highway operation speed transition section,the paper summarizes the matters needing attention in the design of highway operation speed transition section,in order to provide certain reference value for relevant personnel.展开更多
文摘On March 31, in accordance with the typical design requirements of the State Grid, the f irst large electric vehicle (EV) charging station, built by the North China Grid,
基金the financial support for this research from the National Natural Science Foundation of China(52176063)the International Science and Technology projects of Huangpu District of Guangzhou City(2020GH08)the Guangzhou Science and Technology Plan Project(201907010036)。
文摘The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is proposed in this study,i.e.a half separated-half coupled cathode(HSHC)flow field which has two inlets but just one outlet.A 3D numerical PEMFC model is applied to study the effect of the HSHC flow field on PEMFC performance and its operating strategy in terms of operating conditions.The study results are shown as follows:Compared with the two conventional cathode flow fields,the HSHC flow field improves the water balance along the channel and increases the current density by 17.1%at a cathode stoichiometry of 3.25.It is because the HSHC flow field can overcome the water loss at channels upstream and the water accumulation at channels downstream.The draw water phenomenon(DWP)in the HSHC flow field is observed,which is mainly affected by the water vapor pressure of channel.Based on the DWP,cooling channel inlet flow rates can be used to adjust water balance,but severe water loss should be avoided.In addition,the inlet temperature control in HSHC flow field should be that cell temperature>cathode channel inlet temperature>cooling channel inlet temperature>ambient temperatures for better water balance.
文摘In this paper,combined with the relevant speed theory and characteristics of the law,the current highway speed transition design problems are studied and analyzed.In the process of specific analysis,mainly combined with the characteristics of different types of highway speed changes and road section design requirements,this paper studies and analyzes the design methods of different types of highway speed transition section.And on this basis,according to the design principles and requirements of highway operation speed transition section,the paper summarizes the matters needing attention in the design of highway operation speed transition section,in order to provide certain reference value for relevant personnel.
