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HFC-134a热催化降解的实验与机理研究

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工程热物理学报 2024年第4期45卷 935-941页

作者：张凯许云婷王天浩戴晓业史琳清华大学能源与动力工程系北京100084 清华大学热科学与动力工程教育部重点实验室北京100084

2021年9月《蒙特利尔议定书》基加利修正案对我国正式生效,我国在未来三十年左右将面临严峻的HFCs淘汰任务,因此实现淘汰HFCs的高效率、低能耗降解至关重要。传统的高温焚烧工艺存在能耗高、成本高的特点,因此本研究关注于制冷剂热催化... 详细信息

2021年9月《蒙特利尔议定书》基加利修正案对我国正式生效,我国在未来三十年左右将面临严峻的HFCs淘汰任务,因此实现淘汰HFCs的高效率、低能耗降解至关重要。传统的高温焚烧工艺存在能耗高、成本高的特点,因此本研究关注于制冷剂热催化降解方法,选取主要的HFCs类制冷剂HFC-134a为研究对象,通过实验手段和量子化学计算方法探究HFCs制冷剂的热催化方案可行性,并分析了催化剂种类、温度和氧气比例等关键因素对制冷剂降解效果的影响。

关键词： HFC-134a 热催化降解热催化剂影响因素分解机理

欧盟PFAS限制提案解读及其对制冷空调行业影响与应对

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制冷学报 2024年第2期45卷 22-29页

作者：安青松侯佳鑫史琳戴晓业天津大学机械工程学院天津300350 清华大学能源与动力工程系北京100084

在《〈关于消耗臭氧层物质的蒙特利尔议定书〉基加利修正案》的履约和“双碳”目标的双重驱动下,制冷剂替代是制冷空调领域最为关注的热点之一。采用热物性相近的低GWP的HFOs制冷剂和天然制冷剂作为替代品,实现HFCs的削减被认为是较为... 详细信息

在《〈关于消耗臭氧层物质的蒙特利尔议定书〉基加利修正案》的履约和“双碳”目标的双重驱动下,制冷剂替代是制冷空调领域最为关注的热点之一。采用热物性相近的低GWP的HFOs制冷剂和天然制冷剂作为替代品,实现HFCs的削减被认为是较为合适的替代技术路线;但随着2023年2月欧盟出台的PFAS限制提案,引发了对HFOs制冷剂替代前景的担忧,这可能影响全球制冷剂替代发展。因此,首先对PFAS物质进行了介绍,分析了含氟制冷剂与PFASs的关系,并对PFAS法案的形成脉络和关键内容进行了解读,总结了不同领域对此的观点,希望对未来制冷剂替代方案的制定提供一定思辨意义和参考价值。

关键词：制冷剂替代欧盟PFAS法案 PFASs HFOs 基加利修正案

Material Compatibility of Hexamethyldisiloxane as Organic Rankine Cycle Working Fluids at High Temperatures

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Journal of Thermal Science 2020年第1期29卷 25-31页

作者： dai xiaoye SHI Lin QIAN Weizhong Department of Chemical Engineering Tsinghua UniversityBeijing 100084China Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China

The organic Rankine cycle(ORC)is a promising technology for industrial waste heat recovery and renewable energy *** temperature ORCs have attracted particular interest because of their high thermal efficiencies and *** material compatibility of working fluid is a significant limitation for the working fluid selection and system design for high temperature *** work presents a method for studying the material compatibility of ORC working fluids based on the calculated conditions of the ORCs and matching of components,temperatures,and ***(MM)was chosen as the test *** experimental results show that 304 stainless steel has better compatibility with MM than copper as the material of *** rubber is not a suitable sealing material for high temperature ORCs with MM as the working fluids because of the bad *** oil has better compatibility with MM than polyol ester(POE)lubricant as the lubricant for the fluid pump.

关键词： organic Rankine cycle(ORC) material compatibility high temperatures hexamethyldisiloxane(MM)

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赤藓糖醇相变材料的热稳定性评估

工程热物理学报 2024年第8期45卷 2223-2229页

作者：库尔班江·乌丝曼王天浩戴晓业史琳清华大学能源与动力工程系北京100084 新疆大学电气工程学院乌鲁木齐830046

糖醇作为具有性能优异的中温相变储热材料备受关注,其热稳定性是制约材料实际使用的重要物性参数。本文以赤藓糖醇为研究对象,从质量损失、熔点变化、熔化焓衰减这三个指标综合评价了其热稳定性,并建立了其热稳定性评估的动力学模型。... 详细信息

糖醇作为具有性能优异的中温相变储热材料备受关注,其热稳定性是制约材料实际使用的重要物性参数。本文以赤藓糖醇为研究对象,从质量损失、熔点变化、熔化焓衰减这三个指标综合评价了其热稳定性,并建立了其热稳定性评估的动力学模型。结果表明,赤藓糖醇加热后的主要气态产物包括多种小分子气体,固态产物主要体现在C=O键的生成。对质量损失、熔点和熔化焓等热稳定性表征参数变化进行了对比,发现赤藓糖醇熔化焓在空气氛围、145℃、48 h下降了10.2%,变化幅度明显高于其他两个指标,因此选择熔化焓衰减作为赤藓糖醇热稳定性评价指标。在氮气(N_(2))氛围下熔化焓衰减模型的活化能为80.0 kJ·mol^(-1),对数指前因子为15.14 h^(-1)。基于模型进一步分析,在120~140℃下赤藓糖醇熔化焓半衰期为2401~7851 h。

关键词：赤藓糖醇热稳定性质量损失熔点熔化焓

Review of the Working Fluid Thermal Stability for Organic Rankine Cycles

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Journal of Thermal Science 2019年第4期28卷 597-607页

作者： dai xiaoye SHI Lin QIAN Weizhong Department of Chemical Engineering Tsinghua UniversityBeijing 100084China Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China

The organic Rankine cycle(ORC)is an efficient power generation technology and has been widely used for renewable energy utilization and industrial waste heat *** stability is a significant property of ORC working fluids and is the primary limitation for working fluid selection and system *** paper presents a review of the working fluid thermal stability for ORCs,including an analysis of the main theoretical method for thermal stability,a summary of the main experimental method for thermal stability,a summary of the decomposition experimental results for working fluids,and a discussion of the decomposition influence on ORC *** research trends of thermal stability are also discussed in this paper.

关键词： organic Rankine cycle(ORC) working fluid thermal stability

Feasibility Analysis of the Operation Strategies for Combined Cooling, Heating and Power Systems (CCHP) based on the Energy-Matching Regime

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Journal of Thermal Science 2020年第5期29卷 1149-1164页

作者： FENG Lejun dai xiaoye MO Junrong SHI Lin Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China

Although numerous studies have considered the two traditional operation strategies:following the electric load(FEL)and following the thermal load(FTL),for combined cooling,heating,and power(CCHP)systems in different case studies,there are limited theoretical studies on the quantification methods to assess the feasibility of these two strategies in different load demands ***,instead of a case study,we have undertaken a theoretical analysis of the suitable application scenarios for FEL and FTL strategies based on the energy-matching performance between systems'provision and users'*** compare the calculation models of energy saving rate(ESR)for FEL and FTL strategies in the left and right sub-regions of the energy-supply curve,a comprehensive parameter(^)that combines three inherently influential factors(off-design operation parameter,energy-matching parameter,and install capacity coefficient)is defined to determine the optimal installed capacity and feasibility of FEL or FTL strategies *** results indicate that greater value of x contribute to a better energy saving performance,and FEL strategy shows better performance than FTL in most load demands scenarios,and the optimal installed capacity occurs when the load demand points were located in different regions of the energy-supply ***,taking a hotel in Beijing as an example,the value of the optimal install capacity coefficient is 0.845 and the FEL strategy is also suggested,and compared to the maximum install capacity,the average values of the ESR on a typical summer day,transition season,and winter can be enhanced by 3.9%,8.8%,and 1.89%,respectively.

关键词： combined cooling heating and power systems(CCHP) energy-matching performance operation strategies comprehensive parameter energy saving performance

A Comprehensive Experimental Study on Immiscible Displacements in Porous Media:Effects of Capillary Forces,Viscous Forces,Wettability and Pore Geometries

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Journal of Thermal Science 2021年第6期30卷 2137-2149页

作者： HUANG Chao dai xiaoye SHI Changxing SHI Lin Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Thermal Science and Power Engineering of Ministry of Education of China Beijing 100084China Key Laboratory for C02 Utilization and Reduction Technology of Beijing Beijing 100084China Department of Mechanical and Industrial Engineering University of Illinois at ChicagoChicago 60607United States

Immiscible displacements in porous media are fundamentally significant for many natural processes and industrial *** extensive work has been done in this field,some limitations still exist due to the difficulty to cover the large number of influencing *** this paper,we present a systematic study involving the coupled influence of capillary forces,viscous forces,wetting properties and pore *** microfluidic experiments with high resolutions,both residual fluid distributions and dynamical invasion processes were clearly captured and quantitatively characterized.A void-filling behavior was identified for drainage as the capillary number Ca *** anomalous void-leaving behavior was found for the case of imbibition with an unfavorable viscosity ratio M,representing many ribbon-like regions invaded at intermediate Ca turned to be not accessible at high Ca.A pore geometry with a large typical pore-throat ratio seemed to enhance the void-leaving *** the dynamical invasion processes,an intermittency behavior was captured in the form of a fluctuation of the increasing rate of the invading saturation with *** intermittency dynamics were most evident for drainage with an unfavorable M.A pore geometry with high porosity acted to suppress the intermittency *** experimental results sketched out a full view of immiscible displacements in porous media under different conditions,and provided a complete dataset which could be used to test the rapid developing pore-scale models.

关键词： immiscible displacements porous media microfluidic experiments fluid distributions intermittency dynamics

Study of Variable Turbulent Prandtl Number Model for Heat Transfer to Supercritical Fluids in Vertical Tubes

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Journal of Thermal Science 2018年第3期27卷 213-222页

作者： TIAN Ran dai xiaoye WANG Dabiao SHI Lin Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power Engineering Tsinghua University Department of Chemical Engineering Tsinghua University

In order to improve the prediction performance of the numerical simulations for heat transfer of supercritical pressure fluids, a variable turbulent Prandtl number(Pr_t) model for vertical upward flow at supercritical pressures was developed in this study. The effects of Pr_t on the numerical simulation were analyzed, especially for the heat transfer deterioration conditions. Based on the analyses, the turbulent Prandtl number was modeled as a function of the turbulent viscosity ratio and molecular Prandtl number. The model was evaluated using experimental heat transfer data of CO_2, water and Freon. The wall temperatures, including the heat transfer deterioration cases, were more accurately predicted by this model than by traditional numerical calculations with a constant Pr_t. By analyzing the predicted results with and without the variable Pr_t model, it was found that the predicted velocity distribution and turbulent mixing characteristics with the variable Pr_t model are quite different from that predicted by a constant Pr_t. When heat transfer deterioration occurs, the radial velocity profile deviates from the log-law profile and the restrained turbulent mixing then leads to the deteriorated heat transfer.

关键词： Turbulent Prandtl Number Supercritical Fluid Heat Transfer

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火电厂源侧综合能源系统集成及性能评估研究

制冷技术 2024年第1期44卷 24-30页

作者：员盼锋丹慧杰牛国平徐舒涵戴晓业史琳西安西热锅炉环保工程有限公司陕西西安710061 清华大学能源与动力工程系北京100084

本文建立了以火电厂为核心,消纳可再生能源并提供冷热电汽综合能源服务的一套能源系统,通过对整体系统及关键子系统热力性能分析,验证了提出模型和方法的有效性。并研究了一些关键运行参数对系统综合性能的影响,验证了提出模型和方法的... 详细信息

本文建立了以火电厂为核心,消纳可再生能源并提供冷热电汽综合能源服务的一套能源系统,通过对整体系统及关键子系统热力性能分析,验证了提出模型和方法的有效性。并研究了一些关键运行参数对系统综合性能的影响,验证了提出模型和方法的有效性和优越性。结果表明:通过改变火电厂的源侧参数,可以提高综合能源系统荷侧的输出量;且生物质转化气对汽轮机发电功率的影响最大。热泵系统的负荷随着进入系统中的给水流量的增大而增大,利用汽轮机中的部分抽汽来驱动热泵系统,虽然发电功率下降了10.88%,但是却为用户提供了16.8MW的热负荷和16.2MW的冷负荷以及27.78t/h的蒸汽量。

关键词：综合能源系统厂源侧冷热电汽四联供热泵