| Proton Exchange Membrane Fuel Cell(PEMFC)vehicle(s),have become the focus of the industry as a kind of zero emission and long endurance solution,they are not limited by Carnot cycle compared with the traditional internal combustion engine,in addition,they have such advantages as high energy conversion efficiency,non-violence working process,low operating noise,the only production is drinkable water,friendly environment.When PEMFCs suffer from forced collision and get burned,hydrogen can rise quickly because of its low density and dilute with air so it will hardly explode.Compared with the burgeoning lithium-ion battery vehicle(s),PEMFCs can work continuously by supplying fuel,and thus have a long endurance mileage and short charging time,which are also the bottleneck of the current electric vehicles.Meanwhile,PEMFC system has simple structure and diversified fuel sources,large or small scale applications are both available.If hydrogen is produced by electrolysis,the whole life cycle emission will be 50% lower than that of traditional vehicles,while 15% lower by methanol reforming.To sum up,PEMFC may become the mainstream power source of future cars.PEMFC operate in a strictly temperature and humidity requirements,as a result their complex hydrothermal management become the significant factor of limitation of volume production,considering the intake system and cooling system is the most important media for stack in material and energy exchanging with the outside world,inlet parameters such as humidification,inlet pressure,inlet temperature,inlet flow rate and cooling water flow rate,will directly influence the hydrothermal balance inside,reasonable parameter setting can not only improve the performance of the stack,but also extend its service life.In this paper,work is done for the key parameters of PEMFC supply system as follows:(1)150w water cooling PEMFC test platform was designed and constructed,including hydrogen gas inlet system,air inlet system,cooling water circulation system,nitrogen purging system,exhaust system,humidification system,data acquisition system and safety protection system.Firstly parameters of PEMFC system were calculated,according to which key components and instruments were selected,then a range ofschemes on how to arrange the fluid pipes were proposed.The aesthetics and economy of the design were taken into account on the basis of ensuring the safe conduct of the experiment(2)A three-dimensional model of PEMFC single channel was established with Solidworks and imported in COMSOL multiphysics.In the module definition,following modules were introduced and coupled mutually: Secondary Current Distribution(siec)?Transport of Concentrated Species(tcs)?Brinkman Equation(br)?Heat Transfer(ht).(3)The test platform was established and employed for three-dimensional model calibration.Parameters of PEMFCs were changed respectively involving humidifying rate,intake pressure,intake temperature,intake flow rate and cooling water flow rate.The distribution of reaction gas and liquid water in gas channel(GFC)and diffusion layer(GDL)under different operating conditions was investigated.The polarization curve and power density curve of PEMFC were obtained by voltage scanning.The pressure drop and temperature diffusion field were also investigated in some special groups.(4)According to the research results,two schemes were proposed:(1)optimizing the intake system in the shape of GFC.(2)introducing porous media into the GFC.Two different structural layout schemes were put forward for each,which were compared with the primitive group before optimization from different dimensions.This paper mainly analyzes the external characteristics of PEMFC from three perspectives of theoretical analysis,simulation and experimental testing,systematically analyzes the influence of key parameters of the supply system on the performance of the stack,beyond that proposes some optimization schemes,which are of certain reference for the development of PEMFC in the future. |
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