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根据光伏电池的转换特性,详细分析温度对光伏电池开路电压、短路电流、填充因子及转换效率的影响。并设计测试平台,对多晶硅光伏电池实际输出转换效率的温度特性进行了实验研究。结果表明,硅光伏电池输出开路电压随温度升高的减少率约为-2.3mV/K,理想填充因子随温度升高的减少率约为-4.5×10-4/K,短路电流随温度增加而增大,其随温度升高的增加率约为1.21mA/K。总体而言,光伏电池转换效率随温度增加而减少。同时,实验结果也证明多晶硅光伏电池实际输出效率随其温度升高的减少约为-0.22%/K,实验结果与理论分析基本一致。研究结果为光伏系统的优化设计提供了理论及实验基础。 相似文献
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一、概述“燃料电池”是以循环充电方式和传统的汽轮机或燃气轮机联合运行。当燃料电池容量是系统容量的30~40%时,可以获得较低的电能成本,在这种情况下,燃料电池的效率可以高于50%,使投资效益更好。燃料电池(见图1)通过化学反应,可以把能量直接转化为电能。作为反应物的燃料和氧化物分别供给电池的阴极和阳极,在那里发生电-化学反应。电极由传送离子的电解液隔开,电-化学反应和通过电解液传送的离子相结合,产生电位差,从而引起电流的流动。 相似文献
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质子交换膜燃料电池(PEMFC)可以提供较高的功率/能量密度,是未来空间探索最有前途的动力设备之一,其性能主要取决于内部反应物的传输和水管理。气体扩散层(GDL)作为燃料电池中的重要组成部件,与燃料电池的质量、水、热和电的多相传输紧密相关,是反应物和液态水的主要传输场所。因此,要提高燃料电池性能,合理的气体扩散层的设计至关重要。从提升空间燃料电池的使用寿命、稳定性及电化学性能的角度出发,综述了气体扩散层的物理化学特性,并介绍了多种改性方法,包括疏水性、结构和新型一体式GDL以及其对燃料电池性能的影响,为未来空间燃料电池高性能GDL设计提供了参考。 相似文献
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燃料电池的耐久性和寿命是制约其商业发展的重要问题,特别是在动态负载环境下,电池的性能衰减与寿命变短问题更加突出。介绍了首次利用麦克斯韦电磁理论研究电池内部电流分布,并从理论上阐述电池在动态负载输出时,电池内电流密度分布不再均匀,且随着电流变化频率的增加,电流密度越来越向电池外围集中的现象,即电流的趋肤效应:从电池的实际运行与负载取电模式,说明了燃料电池产生电流趋肤效应的情况。最后还通过对单电池作了简化模拟分析,从数据上说明了当负载变化频率大于1kHz时,电池内部将产生严重的电流趋肤效应。说明了电流趋肤效应是燃料电池在动态负载环境下性能衰减与寿命变短的重要原因之一。 相似文献
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固体氧化物燃料电池(SOFC)以其高能量转换效率、高比功率、无运动部件、堆积结构以及环境友好等特点日益受到重视。文章从燃料电池本体以及基于燃料电池的混合发电系统两方面对发达国家固体氧化物燃料电池的发展进行了调查,通过不同国家开发的电池以及混合发电系统的比较分析,对今后固体氧化物燃料电池的发展起到一定的指导作用。基于对燃料电池外形尺寸、进气道的尺寸和形状等电池结构进行了分析,得出不同结构下电池性能的变化,得到了最有利于燃料电池性能的设计参数。研究结果表明,低电流时,随着多孔电极进气道孔径的增加,电池输出电压也降低;而高电流时,电池输出电压先增大后减少,在孔径为5 mm时电池输出电压最大。 相似文献
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质子交换膜燃料电池(PEMFC)通常在为电动车提供电力的同时,也要产生相当数量的废热(约40%~60%)。为了提高质子交换膜燃料电池混合电动车的能量利用率,提出了将温差发电机作为PEMFC的废热回收装置,使其能利用PEMFC低品位的热能进行二次发电并用于锂电池的在线充电。通过对该热电联供系统的热力学分析,得出了温差电池在PEMFC不同运行温度下的发电功率。试验结果显示,此系统可以在提高能量综合利用率的同时,降低对车载锂电池尺寸的设计要求。 相似文献
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A 100 kW regenerative Brayton heat engine driven by the hybrid of fossil fuel and solar energy was considered for optimization based on multiple criteria. A thermodynamic model of such hybrid system was developed so that the power output, thermal efficiency and dimensionless thermo-economic performance with the imperfect performance of parabolic dish solar collector, the external irreversibility of Brayton heat engine and conductive thermal bridging loss could be obtained. Evolutionary algorithm based on NSGA-II (Elitist Non-dominated Sorting Genetic Algorithm) was employed to optimize triple-objective and dual-objective functions, where the temperatures of hot reservoir, cold reservoir and working fluid, the effectiveness of hot-side heat exchanger, cold-side heat exchanger and regenerator were considered as design variables. Using decision makings, including Shannon Entropy, LINMAP and TOPSIS methods, the final optimal solutions were selected from Pareto frontier obtained by NSGA-II. The results show that there exists an appropriate working fluid temperature to cause optimal solution under each given condition. The comparisons of triple-objective and dual-objective optimization with single-objective optimization indicate that multi-objective optimization can yield the more suitable results due to the lower deviation index from the ideal solution. In the analysis of triple-objective optimization, an expected result is obtained that the optimal values of the power out, efficiency and dimensionless thermo-economic performance of solar-dish Brayton system (68.65 kW, 0.2331 and 0.3077) are 22.6%, 34.9% and 18.4% respectively less than that of convectional Brayton heat engine. Finally, a range of functional relationship between the optimized objectives in Pareto frontier is fitted to provide more detailed insight into the optimal design of solar-dish Brayton system. 相似文献
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氢燃料电池是一种将燃料(和氧化剂)的化学能连续地转化为电能的装置。氢燃料电池以化学方式实现能量转换,不受热发动机卡诺循环的限制,具有较高的转换效率。氢燃料电池在全球大范围环保发展下已成为最清洁环保的电动汽车用电池。介绍了氢燃料电池的发展历程、工作原理、优缺点以及氢燃料电池电动汽车的应用实例,展望其发展前景。 相似文献
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燃料电池是氢储能中的重要组成部分,其运行效率对含氢储能的综合系统的经济性有较大影响。为此,提出考虑燃料电池变工况特性的风-光-氢综合能源系统优化调度方法。通过分析燃料电池输出功率和运行效率间的关系,建立燃料电池变工况条件下运行效率的分段线性化模型。提出考虑燃料电池的变工况效率特性的多模块输出功率协同优化策略和燃料电池多模块工作协同策略,从而提升燃料电池总体运行效率和各模块使用寿命。基于此,以风-光-氢综合能源系统优化调度为例,验证了所提优化运行策略的有效性。 相似文献
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The concerns over atmospheric pollution and dwindling petroleum supplies continue to stimulate research on new, clean, and fuel?efficient vehicle technologies. Electric vehicles have not been accepted by the general public due to the high cost of batteries and limited range. Although hybrid electric vehicles with gasoline or diesel engines have addressed the problem of limited vehicle range and reduce emissions, they still discharge emissions and consume petroleum. Hydrogen fuel cells are being considered as an ideal candidate for future vehicles, due to their high efficiency and near-zero emission. However, fuel cell vehicles are thought to be more of a long-term reality because of their high cost and low reliability. Compared with using the fuel cell as a power source, the hydrogen internal combustion engine achieves economic feasibility. Based on existing engine technologies, the hydrogen engine can be a low-emission, low-cost, and practical alternative in the near future to compete with the fuel cell. Many research achievements have indicated that the potential for the hydrogen engine to operate as clean and efficient power source for vehicles is well established. 相似文献