【作者】 赵玺灵；

【导师】 邹平华； 段常贵；

【作者基本信息】 哈尔滨工业大学 ， 供热、供燃气、通风及空调工程， 2007， 博士

【摘要】 燃料电池发电技术是一种先进、清洁的发电技术,其发电机理与传统发电方式不同,其发电效率不受卡诺循环效率的限制,是一种高效的发电设备。将燃料电池作为建筑物热电联供系统的发电装置,是将高效的能源转换方式与高效的能源利用方式的综合,具有一定的研究价值,该领域的研究对提高能源利用率、改善环境质量等方面都具有重要的意义。本文首先从热力学角度对燃料电池发电技术进行分析,与传统发电方式进行比较,并且将处于优势地位的两种燃料电池在建筑物中的应用进行对比分析,针对固体氧化物燃料电池( SOFC)在建筑物热电联供系统(BCHP)中的应用这一课题,在以下几个方面进行研究:建立以天然气为燃料的直接内部重整固体氧化物燃料电池(DIR-SOFC)电堆模型,求解并验证模型的可用性,该模型是一个可以被灵活运用到不同的电池尺寸和操作条件下的模拟模型。在此基础上,模拟DIR-SOFC电堆的性能,分析其性能规律,确定电堆的合理操作区域。综合DIR-SOFC电堆模型与系统中配套的其他辅助设备模型,集成系统,通过对设计工况的模拟,实现SOFC系统的设计;通过对运行工况的模拟,分析系统的运行情况,形成一套适用于SOFC系统的设计思路和模拟方法。对SOFC系统的操作参数进行研究,分析预重整操作温度、预重整比率、蒸汽和碳的比率对系统性能的影响,并详细分析控制参数变化对系统性能的影响,提出四种可行的调节控制方法,通过对四种调节控制方法的综合效率、操作区特性、热电调节范围等各项性能指标的分析得出:以电池的操作温度和燃料利用率为控制参数的调节方法和以电池的操作电压和操作温度为控制参数的调节方法更适合用于建筑热电联供系统中。对SOFC系统进行优化设计,首先建立一个简化的SOFC系统的经济模型,采用指数缩放法处理经济模型中规模与造价的问题,然后从流程结构、设计参数和操作点三方面对系统进行优化设计:在流程结构的研究中,分别对5种不同流程进行模拟,从系统的热、电效率、热电比、初投资和寿命周期费用等方面进行综合评价;在设计参数的研究中,采用多因素析因试验和多变量方差分析的方法,得出燃料利用率、过量空气比率、燃料和空气进入电堆的设计温度为系统的主要设计参数,并分析各个设计变量对系统的技术和经济性能的影响,得到输出变量关于显著影响因素的回归模型,通过等值线图和响应曲面图描述多个非独立变量的变化情况;在系统操作点的研究中,以系统的主要设计变量为优化对象,以寿命周期费用最小为优化目标,采用有约束优化的方法对系统的操作点进行寻优,并逐一放松约束条件,研究不同电流密度条件下,约束条件对系统最佳操作点的影响趋势。对固体氧化物燃料电池建筑热电联供系统(SOFC-BCHP)的设计策略和运行策略进行优化研究,分别提出在高热、电比条件下和高电需求条件下相应的设计策略,特别是应燃料电池发电的特点提出差点设计法的原理,进而提出目前可以适用的电负荷跟随加外电网补充的操作策略。设计SOFC-BCHP系统并进行性能模拟,研究SOFC内部参数变化对系统的影响。针对SOFC-BCHP系统的集成匹配问题,分别从设备容量、设备配置数量、运行操作策略三个层次上以运行费用最小为优化目标,建立匹配问题的优化模型,采用序列二次规划法(SQP)寻优,其中,在对系统配置数量优化的研究中,提出用高频负荷工况的概念来确定设备数量的方法。最终,模拟实例建筑SOFC-BCHP系统的逐时运行匹配模式,并计算系统逐时综合效率、节省费用和CO2减排量,更为详细的分析结果为系统的设计及优化提供重要的理论参考。针对SOFC-BCHP系统的部分负荷优势,指出传统的技术评价指标不能体现系统的年运行工况、运行时间的不足,提出动态评价的概念,将传统的静态技术评价指标改进为“动态第一定律效率”和“动态第二定律效率”两类指标,并在此基础上提出“年一次能耗因子”(Annual Primary Energy Gene)和“年二次能耗因子”(Annual Second Energy Gene)两个新的技术评价指标,并通过实例分析证明了新评价指标的合理性,进而指出该系统在负荷需求持续、热电比需求接近1.6、冷电需求接近1的场合更具应用前景。随着燃料电池技术的日趋成熟,该系统不但为能源利用率的提高、污染物排放的减少提供了契机,而且具有能广泛应用于能量末端用户中的潜力,本文的研究成果为SOFC-BCHP系统的成功应用奠定了理论基础。更多还原

【Abstract】 Fuel cell technology based on natural gas is a kind of promising and cleaning energy conversion technology under development for application. The generation mechanism of fuel cell is different from the traditional device,and the efficiency is not restricted to Carnot cycle, therefore, it is almost the highest efficiency generation device. Fuel cell as the motor of building cogeneration system is the integration of high efficiency energy conversion type with high efficiency energy utilization method.The research work has the significance of energy utilization ratio and environment quality improvements.In this paper, the thermodynamics comparison of fuel cell technology and the convetional generation technology has been done,and two kind of advantaged fuel cells in building application has been analyzed, and then, solid oxide fuel cell distributed energy systems application has been determined as the research object. The main research work are as followed:Firstly,the direct internal reform solid oxide fuel cell(DIR-SOFC) model has been established and validated based on mass and energy balances coupled with appropriate expressions for the reaction kinetics, thermodynamic constants and material properties,and it is a flexible simulation tool, which could easily be adapted to different cell geometries and operation conditions,and then,the fuel cells performance characters have been simulated and analyzed,and the operation region has been determined.Secondly,the stack and other components models have been integrated succesfully.The system design has been finished such as stack areas and components capacities determination, and the run condition has been simulated. The design method which is applicable in SOFC systems process design has been formed.Thirdly,the operation parameters has been investigated.The performance effects were analyzed under different prereform temperature, prereform ratio,the steam to carbon ratio (STCR), and control parameters variety. Four kinds of feasible modulation methods have been put forwarded,and the comprehensive efficiency, operation region characters,and modulation range of heat and electric have been compared under four methods, and the modulation methods of operation temprature and fuel utilization as control parameters and operation temprature and operation voltage as control parameters have been approved to appropriate for building cogeneration system.Fourthly,the process design route of SOFC combined heat and power system has been proposed according to different energy consumption characters. A predigested economic model has been established in which the relation of scale and cost was disposed by index scaling method,and then the system was optimized from the aspects of flow Configuration and parameters.In the first aspects,five flowsheet Configurations were simulated and heat efficiency, electric efficiency, capital cost and life cycle cost was analyzed.In the second aspects,the factorial experiment and multiway analysis of variance were used to distinguish the significant and subordinate variable,and to analyze the variable effects on systems’technic and economic performance,and then the regression model, conour plot, and response surface method were used to indicate the relationship between dependent and independent variable.The optimist operation point was found by constraind optimization model which let the life cycle cost as the optimization object,furthermore,the constrained conditions were relaxed and the constrained condition effects trends on optimist point has been analyzed under two current density levels.The design strategy and operation strategy of SOFC building cogeneration system were investigated. The design strategy was proposed under high heat to electric ratio and high electric demand as followed,heat transformation,surplus power utilization,heat utilization deeply,fuel cell modulation, grid suppletion, power transformation, difference point design, and then, indicated that the electric load followed and grid suppletion added is applicable.The integrated dispatch problem was optimized on equipment capacity, quantity, and run strategy, the production cost was as optimization object and the Sequential Quadratic Programming was as the method and the high frequency load condition concept was proposed to determine equipment quantity.At last,an office case was simulated all year, and the comprehensive efficiency, cost save,CO2 emmisions reduction was computed, the detailed results could be the guidline for system design and optimization. Lastly,The paper indicated the conventional technical evaluation index’s insufficiency, and proposed the concept of dynamic evaluation method which could describe the fuel cell partload advantage.The conventional index was ameliorated to dynamic first law efficiency and dynamic second law efficiency , and annual primary energy gene and annual second energy gene were defined, and then, the applicability was analyzed in different region and different building type,it is indicated that when the load is durative and heat to electric ratio equal to 1.6 and the cold to electric ratio equal to 1, the SOFC building cogeneration system would be more applicable.The system could be the turning point for improvement of energy utilization and reduction of contamination along with the fuel cell technology’s maturity, and have the potential to be used in enduser abroadly.The research conclusions could be the reference for SOFC–BCHP system’s application.更多还原