Performance Characteristics and Parametric Optimum Designs of Water Electrolysis systems for Hydrogen Production and Fuel Cell Systems

能源是经济发展和现代文明的基础。随着全球能源、环境以及气候等问题的日益突出，可再生清洁能源的研发得到了越来越多的关注。众多可再生清洁能源中，氢能因其具有优良的固有属性，成为最具潜力的能源载体之一。电解水制氢是实现大规模制氢从而通往“氢经济”社会的必由之路。而燃料电池是氢能最重要的利用设备之一，可以提供稳定、高效、无污染的动力。因此，对电解水制氢和燃料电池系统开展深入的研究是非常有必要的。 本论文主要研究一些电解水制氢系统和燃料电池系统的性能特性，揭示系统内各主要不可逆性对系统性能的影响，对主要的性能参数进行优化分析，从而建立相应的优化理论，相关的研究内容安排在第二至第五章。 在第二章中，建...Energy is the basis of the economy development and modern civilization. Due to growing concerns about the global energy, environment and climate, the research and development of renewable clean energies has been received more and more attention. Among the various kinds of renewable clean energies, hydrogen energy is considered as one of the most possible universal energy carriers for the future be...学位：理学博士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：1982009015366

Performance Optimization and Parametric Design of a Magnetic Brayton Refrigerator Cycle

基于统计力学和磁工质的热力学性质,建立磁布雷顿制冷机循环新模型,探索热漏、有限速率热传导,绝热过程不可逆性和绝热时间等对循环性能的影响,应用对数平均温差及热力学分析方法,导出制冷率、性能系数的数学表式,并应用数值方法分析、评估磁布雷顿制冷循环的优化性能特性,所得结果为磁制冷机的优化设计和性能改善提供参数设计参考。Based on the statistical mechanics and thermodynamic properties of a magnetic working substance,a new cyclic model of magnetic Brayton refrigerator is established,in which the influence of heat leak,finite-rate heat transfer,adiabatic irreversibilities and adiabatic time are taken into account.By using the Log Mean Temperature Difference(LMTD) and thermodynamic analysis methods,the mathematical expressions of the cooling rate and coefficient of performance(COP)of the magnetic Brayton refrigerator cycle are derived.Furthermore,the optimal performance characteristics of the magnetic Brayton refrigerator cycle are analyzed and evaluated by the numerical calculation technology.The results obtained in the present paper may provide some parametric design message for optimal design and the performance improvement of real magnetic Brayton refrigerators.国家自然科学基金项目(No.50776074

Performance Optimization and Parametric Analysis of an Irreversible Solar-Driven Stirling Heat Engine

建立不可逆太阳能STIrlIng热机循环系统,研究太阳能集热器辐射对流热损、有限速率热传导、回热器的回热损失及其它不可逆因素对系统性能的影响。基于热力学分析方法和最优控制理论,导出系统总效率和集热器工作温度所满足的优化方程,确定和评估相关性能界限和优化设计参数值,并详细讨论包括与传热系数有关的综合因子、回热损失因子以及辐射和对流热损因子比等重要参量对太阳能STIrlIng热机系统性能的定量影响。所得结果为太阳能STIrlIng热机参数优化设计提供理论参考。An irreversible solar-driven Stirling heat engine system is established,in which not only radiation-convection heat losses from the solar collector to the ambient but also the regeneration loss and other irreversibilities of the heat engine are taken into account.Based on thermodynamic analysis method and the optimal control theory,the optimum relationship between the overall efficiency of the system and the operating temperature of the collector are derived and the related performance bounds and optimal value of the design parameters are determined and evaluated.Moreover,the effects of several important parameters including the compositive factor related to the heat transfer coefficient,the regenerative factor and the radiation and convection heat loss coefficient ratio on the performance of the heat engine system are discussed in detail.The results obtained may provide some theoretical references for the optimal parameter design of solar-driven Stirling heat engines.国家自然科学基金资助项目(No.50776074

PERFORMANCE OPTIMIZATION AND PARAMETER DESIGN of AN IRREVERSIBLE SOLAR-DRIVEN HEAT PUMP SYSTEM

考虑集热器辐射对流热损等多种不可逆因素,建立不可逆三热源太阳能热泵系统新模型,基于热力学分析方法,导出系统总性能系数与集热器工作温度关系的解析表达式,揭示了集热器的辐射对流热损、有限速率热传导和工质内部不可逆性等对系统性能特性的影响,分析和讨论了在最大总性能系数下太阳能热泵系统的优化设计参量。A new irreversible solar-driven three-heat-source pump system was presented,in which multi-irreversibilities including the radiation and convection heat losses of the collector were taken into account.Based on thermodynamic analysis method,the analytical expression between the overall coefficient of performance of the system and the operating temperature of the solar collector was derived.The effects of radiation and convection heat losses of the collector,finite-rate heat transfer and internal irreversibility inside the working fluid on the performance characteristics of the system were revealed.Furthermore,the optimal design parameters of the system at the maximum overall coefficient of performance were analyzed and discussed.国家自然科学基金(51176160);教育部高校博士点基金(20090121110026);中央高校基本科研业务费专项基金(201112G006

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^