磷酸燃料电池与吸收式制冷机复合系统性能优化分析

发布时间：2018-03-10 03:36

本文选题：磷酸燃料电池　切入点：复合系统　出处：《东华大学》2017年硕士论文　论文类型：学位论文

【摘要】：21世纪是能源世纪,世界各国致力于发展新的能源技术以摆脱传统的化石能源带来的环境污染,效率低下等问题。其中分布式能源系统,特别是以高能量密度的燃料电池为基础的能源系统,因其配置灵活,清洁环保、安全可靠等优势,迅速成为当今能源领域研究的热点。未来我国将加大对智能电网的投资与建设,小型的燃料电池冷热电联供项目因此会获得了极大的发展前景。因此,研究燃料电池与吸收式制冷机的复合系统符合国家发展需求,具有实际意义。本文建立了磷酸燃料电池与吸收式制冷机的复合系统模型,在磷酸燃料电池输出电能的同时,释放的余热驱动吸收式制冷机,为一个建筑房间提供冷量。分别优化分析了磷酸燃料电池性能与复合系统的制冷性能。具体工作有:第一章介绍了当今国内外新能源发展特点以及燃料电池技术的简要发展历程,并举例介绍了国内外燃料电池冷热电联供项目的具体案例与研究的现状。最后说明燃料电池冷热电联供项目在我国的发展前景与研究的意义。第二章研究了磷酸燃料电池(PAFC)的工作机理,通过热力学分析得出燃料电池可逆电压,电化学分析得出使电池实际电压下降的三种过电势:活化过电势、浓度过电势、欧姆过电势。考虑了燃料电池内部不可逆损失,分析了不同工作参数例如温度、压力、电解质浓度等对燃料电池性能的影响,得到了燃料电池实际电压与熵产率。第三章建立了相比三热源循环系统更贴近于实际制冷循环的四热源的吸收式制冷机模型。分析多种工作参数对制冷机性能的影响并优化了其制冷量、性能系数,同时给出了不同工作条件下的优化电流密度区间。将冷量转换为等效功量,计算该复合系统的等效功率与效率,结果显示,效率随着电流密度增加而下降,而复合系统功率存在极值。由于最大制冷量对应的电流密度要小于最大输出功率时的对应电流密度,有多余热量没有被利用,为增加系统能量使用效率,提出了利用热水系统收集燃料电池位于高电流密度区所释放的多余热量。通过计算显示该方法提升了系统效率约为10%。第四章建立了制冷空间的非稳态传热模型,得到了房间温度随时间变化的关系,并设定了目标温度TSET,优化达到目标温度的时间量。分析了不同不可逆因子、工作温度、冷凝器吸收器热量分配率、以及墙体热导率对非稳态的影响,对比得到,不可逆因子与温度对非稳态性能影响较大,而冷凝器吸收器热量分配率影响较小。不同的工作条件下,达到目标温度所允许的电流密度区间不同。与稳态特性不同,优化非稳态特性要求更小的电流密度区间。第五章则对本文研究内容做出总结,分析罗列了本文研究的优点与缺点。为本文的今后研究方向提出了相关看法与展望。
[Abstract]:Twenty-first Century is the energy century, the world is committed to the development of new energy technologies to get rid of traditional fossil energy environmental pollution problems, the efficiency is low. The distributed energy system, especially energy system with high energy density of fuel cells as the foundation, because of its flexible configuration, clean, safe and reliable advantages. Quickly become a hot topic in the research fields of energy. The future of our country will increase the investment and construction of the smart grid, cooling heating and small fuel cell cogeneration project so it will get great development prospect. Therefore, study on complex system of fuel cell and refrigerating machine meets the demand of national development, has practical significance. The system model is established in this paper for phosphoric acid fuel cell and refrigerating machine, the phosphoric acid fuel cell output power at the same time, absorption chiller driven heat release, as a The building room cooling capacity. Optimizing refrigeration performance of phosphoric acid fuel cell performance and composite system are analyzed. The details are as follows: the first chapter introduces briefly the development course of the current domestic and foreign development characteristics of new energy and fuel cell technology, and introduces the specific case and research status at home and abroad of fuel cell cogeneration project at last that fuel cell cogeneration project in China's development prospects and research significance. The second chapter studies the phosphoric acid fuel cell (PAFC) of the working mechanism, the fuel cell can be obtained by thermodynamic analysis of inverse voltage, electrochemical analysis of three kinds of potential as battery voltage drop: activation overpotential. The concentration overpotential, ohmic overpotential. Considering the fuel cell internal irreversibility, analysis of different working parameters such as temperature, pressure, concentration of electrolyte for fuel cell The influence of the actual fuel cell voltage and the entropy production. The third chapter established compared three heat source absorption refrigeration cycle system model more close to the reality of the four heat source refrigeration cycle. Analysis of various working parameters influence on the performance of the refrigerator and optimize its cooling capacity, coefficient of performance, and gives the optimization of current the density range under different working conditions. The cooling load is converted to an equivalent amount of reactive power, calculation of equivalent power and efficiency of the composite system. The results show that the efficiency decreases with the increase of current density, while the composite system has extreme power. Because the corresponding current density corresponding to the maximum cooling capacity is lower than the maximum output power. There is no excess heat is used to increase the system energy efficiency, the excess heat collecting fuel cell at high current density region released by hot water system is put forward. The calculated results show that the proposed method improves the system efficiency established unsteady heat transfer model of refrigeration space is about 10%. in the fourth chapter, the relationship between room temperature change with time, and set the target temperature TSET, optimizing the amount of time to reach a target temperature. Analysis of different irreversible factor, working temperature, condenser absorber heat distribution rate well, the wall thermal conductivity effect on non steady state contrast, irreversible factor and temperature had great effects on the non steady state performance, while the condenser absorber heat distribution was less affected. Different working conditions, the current density reaches the target temperature interval allowed. Unlike steady-state characteristics, current density interval optimization requires a smaller non the steady state characteristics. The fifth chapter makes a summary of the contents of this paper, analysis the advantages and disadvantages are listed in this paper. For the future study of this paper to put forward The relevant views and prospects.

【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.4;TB651

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