非晶二氧化铪(a-HfO₂)由于其宽带隙和高介电常数等优异性能在半导体器件材料中被广泛关注。然而，a-HfO₂热输运性质尚不明确，由此阻碍了它在电子领域的潜在应用。本工作使用基于分子动力学的方法系统地研究了a-HfO₂的热输运性质。非平衡态分子动力学模拟表明，a-HfO₂的热导率在100 nm以下具有明显的尺寸效应。热流谱分解分析方法表明了传播子和扩散子的热输运对系统长度的敏感性。通过格林-久保模式分析方法计算表明a-HfO2的热导率随温度的升高而升高。通过量化不同温度下各热载流子对热导率的贡献，我们发现在低温下(<100 K)，传播子比扩散子对热输运的贡献显著，而在高温下，扩散子主导了热输运。

Hyperloop已成为未来高速轨道交通的关键储备技术之一。管中的气体被压缩和摩擦，带来强烈的空气动力热效应。Hyperloop的流场特性和气动热效应的研究尚处于起步阶段，对流场结构的研究还很缺乏。在本研究中，喷管理论被用来初步判断壅塞流动现象。根据不同工况下的计算结果，获得了Hyperloop中壅流动现象的识别依据。此外，本研究还分析了壅塞/未壅塞流动对管内环形空间流动结构、温度和压力分布的影响。基于传统的高速铁路空气动力学、航空航天领域的相关理论和计算方法，结合模型试验数据，对管内流场特性进行可靠性验证。在壅塞流动下，列车前方会形成正激波。局部流场的温升超过50K，滞止区温升超过88K，压力约为管内初始压力的1.7倍。在未壅塞流动下，与不同的来流马赫数对应的流场分布呈现差异。当来流是超音速时，流场保持超音速，在列车前部形成弓形激波。激波或膨胀波导致局部流场表现出温度和压力的显著波动。相反，当来流是亚音速时，管内的流场保持亚音速，未观察到明显激波结构。

In Iran, the intensity of energy consumption in the building sector is almost 3 times the world average, and due to the consumption of fossil fuels as the main source of energy in this sector, as well as the lack of optimal design of buildings, it has led to excessive release of toxic gases into the environment. This research develops an efficient approach for the simulation-oriented Pareto optimization (SOPO) of building energy efficiency to assist engineers in optimal building design in early design phases. To this end, EnergyPlus, as one of the most powerful and well-known whole-building simulation programs, is combined with the Multi-objective Ant Colony Optimization (MOACO) algorithm through the JAVA programming language. As a result, the capabilities of JAVA programming are added to EnergyPlus without the use of other plugins and third parties. To evaluate the effectiveness of the developed method, it was performed on a residential building located in the hot and semi-arid region of Iran. To obtain the optimum configuration of the building under investigation, the building rotation, window-to-wall ratio, tilt angle of shading device, depth of shading device, color of the external walls, area of solar collector, tilt angle of solar collector, rotation of solar collector, cooling and heating setpoints of heating, ventilation, and air conditioning (HVAC) system are chosen as decision variables. Further, the building energy consumption (BEC), solar collector efficiency (SCE), and predicted percentage of dissatisfied (PPD) index as a measure of the occupants’ thermal comfort level are chosen as the objective functions. The single-objective optimization (SO) and Pareto optimization (PO) are performed. The obtained results are compared to the initial values of the basic model. The optimization results depict that the PO provides optimal solutions more reliable than those obtained by the SOs, owing to the lower value of the deviation index. Moreover, the optimal solutions extracted through the PO are depicted in the form of Pareto fronts. Eventually, the Linear Programming Technique for Multidimensional Analysis of Preference (LINMAP) technique as one of the well-known multi-criteria decision-making (MCDM) methods is utilized to adopt the optimum building configuration from the set of Pareto optimal solutions. Further, the results of PO show that although BEC increases from 136 GJ to 140 GJ, PPD significantly decreases from 26% to 8% and SCE significantly increases from 16% to 25%. The introduced SOPO method suggests an effective and practical approach to obtain optimal solutions during the building design phase and provides an opportunity for building engineers to have a better picture of the range of options for decision-making. In addition, the method presented in this study can be applied to different types of buildings in different climates.

印刷电路板式换热器（PCHE）因其传热效率高、紧凑性好等优点，近年来在S-CO₂循环发电系统中得到了广泛的应用。但PCHE通道构型较多，实际工程应用时缺少构型选择的判断依据。因此，本文针对直通道、之字形通道、波纹通道和翼型翅片通道四种典型PCHE通道构型，在“三场协同”原理的指导下，对通道内流场和温度场以及流场和压力场的协同性进行讨论；进一步，对比分析了四种通道构型的综合换热性能；最后，获得了四种典型通道构型的传热和阻力关联式。结果表明，直通道PCHE的速度场与压力场间协同性较优，因此其阻力损失相对较小。之字形、波纹通道和翼型翅片可以减小速度和温度梯度间的夹角α，从而强化了换热。与之字形通道相比，波纹通道由于具有圆角，因此减小了流动阻力。在本文所研究的Re范围内，所提出的PCHE传热和阻力关联式最大误差为7%，拟合精度良好。本文的研究可为不同通道构型PCHE的选择和设计提供参考。

塑性结晶新戊二醇（NPG）具有庞压卡效应。然而，它们的应用在几个方面受到限制，例如低导热系数、大热滞后和差回弹性能。在本研究中，选择了具有超高导热率和高机械强度的多壁碳纳米管（MWCNTs）来增强NPG的性能。最佳混合比例被确定为NPG与3wt%MWCNTs的复合材料，该复合材料在牺牲较少的相变焓的情况下能够将过冷度降低6K。随后，最佳配比的复合材料的综合性能与纯NPG进行了比较。在40 MPa的情况下，观察到390 J·K^–1·kg^–1的熵变化和9.9 K的温度变化。此外，所需的最小驱动压力降低了19.2%，以实现可逆的压热效应。此外，复合材料的热导率提高了约28%，显著缩短了压热制冷循环中的热交换时间。更为重要的是，超高的压力释放率使复合材料的回弹时间减少了73.7%，为恢复膨胀功提供了新的机会。

开式吸收式系统是一种具有潜力的回收烟气水和余热的技术手段。文献研究表明吸收过程可同时脱除颗粒物。本文采用实验的方法研究了吸收器的细颗粒物脱除效果。实验中所用除湿剂为氯化钙水溶液。实验结果显示，质量平衡偏差不超过±10%，能量平衡偏差不超过±15%，表明了实验数据的可靠性。23.5%-46.0%的细颗粒物与23.9%-45.1%的水分从烟气中被脱除。通过比较除湿剂和水，发现二者对烟气的冲刷无法明显脱除细颗粒物。当除湿剂或水实现了相同的水回收率，二者的细颗粒物脱除率也十分接近。经过实验参数分析，细颗粒物脱除率与水回收率几乎呈线性关系。

气化飞灰是煤气化过程产生的固体废弃物，出于环保要求和资源化利用，亟需对其进行有效处置。为进一步明确气化飞灰资源化利用可能，详细分析了十种循环流化床煤气化飞灰的理化特性。结果表明，气化飞灰普遍具有零水、超低挥发分（0.90%-9.76%）、高碳（37.89%-81.62%）和超细粒径（d₅₀=15.8-46.2 μm）等物性特征。受益于温和气化条件，循环流化床气化过程对固体原料表现出活化作用，气化飞灰的孔隙结构较为发达（SBET=139-518 m²/g），具有疏松多孔的结构特征，部分气化飞灰已具备直接作为多孔碳材料使用的基本条件。气化飞灰具有丰富的无定形碳结构，反应活性良好，具备通过活化进一步改善孔隙结构的潜能。气化飞灰的反应活性和孔隙结构与煤阶密切相关。通常，煤阶越高，气化飞灰的反应活性越差，微孔结构越发达。本研究指明了循环流化床煤气化飞灰在制备多孔碳材料方面的物性优势。

The unsteady cloud cavitation shedding in fuel nozzles greatly influences the flow characteristics and spray break-up of fuel, thereby causing erosion damage. With the application of high-pressure common rail systems in diesel engines, this phenomenon frequently occurs in the nozzle; however, cloud cavitation shedding frequency and its mechanism have yet to be studied in detail. In this study, a visualization experiment and proper orthogonal decomposition (POD) method were used to study the variations in the cavitation shedding frequency and analyze the cavitation flow structure in a 3 mm square nozzle. In addition, large eddy simulation (LES) was performed to explore the causes of cavitation shedding, and the relationship between cavitation and vortices. With the increase of the inlet and outlet pressure differences, and fuel temperatures, the degree of cavitation intensified and the frequency of cavitation cloud shedding gradually decreased. LES demonstrated the relationship between the vortices, and the development, shedding, and collapse of the cavitation clouds. Further, the re-entrant jet mechanism was found to be the main reason for the shedding of cavitation clouds. Through comparative experiments, the fluctuation of the vapor volume fraction in the nozzle hole accurately predicted the regions with stable cavitation, re-entrant jet, cavitation cloud shedding, and collapse. The frequency of cavitation shedding can then be calculated. This study employed an instantaneous POD method based on instantaneous cavitation images, which can distinguish the evolution process and characteristics of cavitation in the nozzle hole of diesel engines.

为克服跨声速流动中对翼型的巨大阻力，提出了一种采用抽吸和加载前缘( SLLE )的混合流动控制方法，并研究了其在不同工况下的主动反馈控制效果。加载前缘结构作为一种被动流动控制技术可以实现压力的重新分配；而抽吸槽用于控制激波位置和流动分离，可以利用反馈控制系统主动、自动地进行。首先，在定常流动下进行研究，得到了显著的减阻性能。攻角为5°时可得到最高的减阻率22.5%，在各攻角情况下均可得到升阻比的增大。其次，针对非设计来流条件下的反馈流量控制问题，提出了一种基于反馈的SLLE控制方法。结果表明，SLLE控制能够获得平均大于10%的减阻性能，表明该流量控制方法在改变流量条件下具有良好的适用性。

In this research paper, a solar air heater with triangular fins has been experimentally analysed and optimized. Initially, an experimental set-up of a solar air heater having triangular fins has been developed at the location of 28.10°N, 78.23°E. The heat transfer rate through fins and fins efficiency has been determined by the Finite Difference Method model equations. The experimental data and modeled data of response parameters have been optimized in MINITAB-17 software by the Response Surface Methodology tool. For creating the response surface design, three input parameters have been selected namely solar intensity, Reynolds number, and fin base-to-height ratio. The range of solar intensity, Reynolds number, and fin base-to-height ratio is 600 to 1000 W/m², 4000 to 6000, and 0.4 to 0.8 respectively. The response surface design has been analyzed by calculating the outlet temperature, friction factor, Nusselt number, fin efficiency, thermal performance factor, and exergy efficiency. The optimum settings of input parameters: solar intensity is 1000 W/m²; Reynolds number is 4969.7, and the fin base to height ratio is 0.6060, on which these response: namely outlet temperature of 92.531°C, friction factor of 0.2350, Nusselt number of 127.761, thermal efficiency of 50.836%, thermal performance factor of 1.4947, and exergy efficiency of 8.762%.

超临界二氧化碳印刷电路板换热器有望应用于第三代太阳能热发电，然而超临界二氧化碳进入换热器时的均匀程度对换热器的综合性能有很大影响，为了提高入口集管对流量分配的均匀程度。本文通过数值模拟的方法对印刷电路板换热器的入口集管进行研究和结构优化。结果表明，当超临界二氧化碳流过集管腔时会产生涡流，涡流会增大流量的不均匀分配，减小涡流的产生会提高流量的均匀分配。当入口集管的无量纲因子为6时，双曲线构型为最优结构。还通过增加过渡段来减小涡流区域，结果表明当扩张角为10°时的结构最好，相比于双曲线构型不均匀度降低了21%，为工程实践提供了指导意义。

导热增强体设计能够有效克服相变材料导热能力低的缺点。本文研究的主要贡献首先是讨论了在相同金属质量的条件下，如何通过在多孔结构中嵌入翅片主动增强熔融相变材料的自然对流，同时提高热传导能力，从而提升相变传热性能。此外，基于增材制造技术设计和制备了混合翅片-点阵结构导热增强体。采用两方程数值方法研究了相变材料的传热过程，并通过实验数据验证了该方法的有效性。数值计算结果表明，在点阵结构中合理地引入翅片不仅有效增强了熔融相变材料的自然对流，同时进一步提高了热传导能力。增强自然对流提高了相变材料的熔化速率以及降低了壁面温度，例如，由于金属铝翅片的存在，完全熔化时间和壁面温度分别降低了11.6%和19.7%。此外，混合翅片-点阵结构的孔隙率、孔密度和翅片尺寸等参数对相变传热有很大影响。随着基体材料热导率的降低，翅片对相变材料熔化速率的增强作用不断增加。例如，对于金属钛基体材料，当翅片被嵌入多孔结构中时，相变材料完全熔化时间减少了24.1%。总之，本研究使我们能够很好地理解相变传热机理，并为增材制造混合翅片-点阵结构设计提供了必要的实验数据。

由于空气分离系统（ASU）和二氧化碳压缩纯化系统（CPU）的存在，循环流化床（CFB）富氧燃烧技术的净发电效率降低。高氧气浓度是提高CFB富氧燃烧技术净发电效率的一种有效手段。在本研究中，基于Aspen Plus平台进行了一系列计算和模拟，为进一步研究高氧气浓度（40%、50%）CFB富氧燃烧系统提供了有用的信息。建立的高氧气浓度CFB富氧燃烧系统模型包括ASU、CPU和CFB富氧燃烧和换热单元，通过对模拟结果进行能效分析和㶲分析获得了以下结论。50%氧气浓度CFB富氧燃烧锅炉炉膛和尾部烟道的横截面积分别为原尺寸的43%和56%，有效降低了建设和投资成本；随着氧气浓度的增加，净发电效率显著提高，在50%氧气浓度时达到了24.85%，提高6.09%；总㶲损失随氧气浓度的增加而增加，此外，辐射传热的㶲损失远高于对流传热。

太阳能与燃料电池技术相结合产生的合成气燃料是未来绿色能源解决碳中和问题的一种很有前景的方法。本文设计了一种新型太阳能驱动固体氧化物电解槽系统，该系统集成了余热系统以制备合成气。太阳能光伏和抛物线槽集热器共同驱动固体氧化物电解槽，以提高系统效率。建立了各部件的热力学模型，并进行了能量、（火用）和（火用经济）分析，以评估系统的性能。在设计工况下，太阳能光伏发电由于其转换效率较低，占总（火用）损失的88.46%。经济性分析表明，燃料电池组件的经济性系数较高，为89.56%，这是因为其投资成本较大。讨论了电流密度、工作温度、压力和摩尔分数等关键参数对系统性能的影响。结果表明，当SOEC的温度、压力和水蒸气摩尔分数分别为1223.K、0.MPa和50%时，最佳能量效率和（火用）效率分别为19.04%和19.90%。

The costs of conventional fuels are rising on a daily basis as a result of technical limits, a misallocation of resources between demand and supply, and a shortage of conventional fuel. The use of crude oil contributes to increased environmental contamination, and as a result, there is a pressing need to investigate alternate fuel sources for car applications. Biodiesel is a renewable fuel that is derived chemically by reacting with the sources of biodiesel. The present research is based on analyzing the effect of fish oil biodiesel-ethanol blend in variable compression engine for variable compression ratio (VCR). The processed fish oil was procured and subjected to a transesterification process to convert fatty acids into methyl esters. The obtained methyl esters (biodiesel) were blended with ethanol and diesel to obtain a ternary blend. The ternary blend was tested for its stability, and a stable blend was obtained and tested in VCR engines for its performance, combustion, and emission characteristics. In the second phase, experiments are conducted in the diesel engine by fueling the fish oil methyl ester and ethanol blended with diesel fuel in the concentration of 92.5 vol% of Diesel+7.5 vol% of Fish oil+1.25 vol% ethanol, 92.5 vol% of Diesel+7.5 vol% of Fish oil+5 vol% ethanol, 87.5 vol% of Diesel+12.5 vol% of Fish oil+1.25 vol% ethanol, 87.5 vol% of Diesel+12.5 vol% of Fish oil+5 vol% ethanol, 82.5 vol% of Diesel+17.5 vol% of Fish oil+1.25 vol% ethanol, 82.5 vol% of Diesel+17.5 vol% of Fish oil+ 5 vol% ethanol to find out the performance parameters and emissions. Because the alternative fuel performs better in terms of engine performance and pollution management, the percentage chosen is considered the best mix. The results showed that the use of a lower concentration of ethanol in the fish oil biodiesel blend improved the engine thermal efficiency by 5.23% at a higher compression ratio. Similarly, the engine operated with a higher compression ratio reduced the formation of HC and CO emissions, whereas the NO_x and CO₂ emissions increased with an increased proportion of biodiesel in diesel and ethanol blends.

The objective of this paper is to understand the benefits that one can achieve for large-scale supercritical CO₂ (S-CO₂) coal-fired power plants. The aspects of energy environment and economy of 1000 MW S-CO₂ coal-fired power generation system and 1000 MW ultra-supercritical (USC) water-steam Rankine cycle coal-fired power generation system are analyzed and compared at the similar main vapor parameters, by adopting the neural network genetic algorithm and life cycle assessment (LCA) methodology. Multi-objective optimization of the 1000 MW S-CO₂ coal-fired power generation system is further carried out. The power generation efficiency, environmental impact load, and investment recovery period are adopted as the objective functions. The main vapor parameters of temperature and pressure are set as the decision variables. The results are concluded as follows. First, the total energy consumption of the S-CO₂ coal-fired power generation system is 10.48 MJ/kWh and the energy payback ratio is 34.37%. The performance is superior to the USC coal-fired power generation system. Second, the resource depletion index of the S-CO₂ coal-fired power generation system is 4.38 μPR_china,90, which is lower than that of the USC coal-fired power generation system, and the resource consumption is less. Third, the environmental impact load of the S-CO₂ coal-fired power generation system is 0.742 mPE_china,90, which is less than that of the USC coal-fired power generation system, 0.783 mPE_china,90. Among all environmental impact types, human toxicity potential HTP and global warming potential GWP account for the most environmental impact. Finally, the investment cost of the S-CO₂ coal-fired power generation system is generally less than that of the USC coal-fired power generation system because the cost of the S-CO₂ turbine is only half of the cost of the steam turbine. The optimal turbine inlet temperature T₅ becomes smaller, and the optimal turbine inlet pressure is unchanged at 622.082°C/30 MPa.

可再生能源的快速增长对燃煤电厂的调峰能力提出了更高的要求。富氧燃烧是燃煤电厂最有前途的碳减排技术之一。本研究提出了一种新型的富氧燃烧发电厂，该发电厂与液氧储存、冷能回收系统相结合，以适应调峰要求。液氧储存系统利用廉价的谷电生产液氧供高峰期使用，增强调峰能力。同时引入冷能回收系统，回收液氧相变过程中的物理潜热，提高高峰期发电量。330 MWe富氧电厂作为参考（案例1）、同一电厂仅配备液氧储存系统（案例2）以及同一电厂同时配备液氧储存和冷能回收系统（案例3），构建了3种不同的富氧燃烧系统，并对各个系统的技术经济性进行了分析和比较，热力学性能分析表明，案例3的调峰容量可达106.03~294.22 MWe，最大调峰系数高达2.77。案例2和案例3在高峰期的总㶲效率分别达到32.18%和33.57%，明显高于案例1的26.70%。经济分析表明，通过出售液态O₂和液态CO₂，结合碳交易，三种案例的平准化度电成本（LCOE）都得到了大幅降低，案例3中最低为30.9 0美元/MWh。综合考虑，案例3可视为未来热力性能和经济性能最佳的富氧电厂参考。

随着新能源的大规模装机，新能源消纳问题愈发严峻，电力系统对调峰及高灵活调节能力资源的需求显著增加。我国的资源禀赋决定了采用燃煤机组调峰及灵活发电在经济性、可靠性和国家能源安全方面具有天然优势。循环流化床机组是燃煤机组的重要组成部分，其本身具有很好的负荷适应性，具有很好的调峰特性，然而由于其炉内有大量的耐磨耐火材料、床料、循环物料、工质以及受热面金属等，锅炉运行过程中积蓄大量热量，形成了循环流化床锅炉的热惯性，成为其变负荷速率提高的主要瓶颈之一，因此，要进一步提高循环流化床机组的负荷响应速率，首先应对其热惯性特性开展系统研究。本文提出采用单位发电功率变化对应的锅炉蓄热量变化量来表征锅炉的热惯性。通过现场采集330 MW 循环流化床锅炉的运行数据，对热惯性进行分析，从而揭示炉内各蓄热体对锅炉总热惯性的影响规律以及在机组不同负荷区间变负荷过程中热惯性的变化规律。此外，还提出了使用高导热防磨材料和金属格栅来替代循环流化床锅炉中传统耐磨耐火材料的优化方案，并对耐磨耐火材料替换后的锅炉热力性能、热惯性及动态特性进行了分析。研究结果表明，炉膛水冷壁和分离回料系统是循环流化床锅炉内热惯性最大的部件，它们的热惯性约占锅炉总热惯性的80%；在不同负荷区间，耐磨耐火材料占总热惯性的比例均超过50%，工质热惯性占比约为25%；循环流化床锅炉在低负荷区间具有更大的热惯性，30%-50%负荷区间的热惯性是75%-100%负荷区间热惯性的约1.6倍。使用金属格栅和高导热材料替代耐磨耐火材料可以有效降低锅炉的热惯性，提高锅炉的变负荷速率和运行稳定性。不同负荷区间负荷变化时，锅炉整体热惯性降幅均约为30%-35%。这种热惯性的减小有助于提高锅炉的变负荷响应速率，满足消纳新能源对火电机组提出的灵活运行需求。

Turbulent two-phase combustion is widely encountered in spray and pulverized-coal combustors, and large-eddy simulation (LES) becomes a powerful CFD method for its simulation, because LES can give unsteady flame structures and more reasonable statistical results than Reynolds-averaged modeling. Present combustion models in LES either lack of generality or are computationally too expensive. A statistical moment model based on the idea of turbulence modeling called “second-order moment (SOM) combustion model” was developed by the present authors for LES of two-phase combustion. In this paper, a review is given on our published research results for SOM-LES of two-phase combustion, including the description of the SOM-LES model, its application, validation of statistical results by experiments, as well as the phenomena obtained by instantaneous results.

本研究提出了一种耦合太阳能的冷热电三联供系统。该系统采用沃尔沃公司制造的内燃机作为原动机，对比了不同容量的原动机在部分负荷下的性能。采用基于遗传算法的多目标优化模型，以便获得同时兼顾成本效益和碳减排量的系统耦合方式。此外，以上海地区某酒店作为研究对象，对所提出的耦合太阳能的冷热电三联供系统的逐时热力性能进行了分析。结果表明，单机容量较大的内燃机的具有较好的热力性能，当集热器数量为90组时，该系统的一次节能率为61.61%。此外，在夏季典型日中，通过回收系统余热和收集太阳热能可以为用户提供全部的热负荷需求；在春秋季节和冬季时，可以采用尖峰锅炉以弥补用能缺口。由于太阳能的引入，系统可以减少CO2排放856.2吨/年。此外，当燃料价格从0.8P增加到1.2P燃料时，系统动态投资回收期将从3.01年变为3.56年。

冷热电联产系统中生物质与太阳能的互补利用为能源危机和环境污染提供了有效的解决方案。本文旨在提出一种基于生命周期评估(LCA)方法的多目标优化模型，用于太阳能与生物质冷热电联供系统的优化设计。通过将多联产系统的生命周期过程划分为6个阶段，来分析能源消耗和温室气体排放。并结合全生命周期环境影响、可再生能源贡献和经济效益等评价指标，对混合系统的综合性能进行了优化。采用结合TOPSIS方法的非支配排序遗传算法II (NSGA-II)来搜索Pareto前沿结果，从而获得最优性能。将所开发的优化方法应用于工业园区的案例研究。结果表明，相较于参考系统，混合系统的性能优化后的效果显著，环境影响负荷降低率(EILRR)为46.03%，可再生能源贡献率(RECP)为92.73%，年总成本节约率(ATCSR)为35.75%。通过比较不同阶段的污染物当量排放量，运行阶段的污染物排放量最大，其次是原料获取阶段。综上可以看出，本文提出的基于LCA的多目标优化模型为设计和优化混合生物质能和太阳能的冷热电联产系统提供了一条潜力路径。

了解连续水热反应器的停留时间分布（RTD）对提高产品质量和反应效率具有重要意义。本工作将在线测量系统连接到一个连续水热反应器上，以研究RTD的特性，并提出了一种通过寻找特征值来拟合和描述实验测量的RTD曲线的方法。通过实验测量了三组实验工况的RTD曲线，并计算了特征值。结果表明，增加总流量和延长有效反应器长度对平均停留时间有相反的影响，但它们都会使反应器内流动更接近平推流，并降低提前流出反应器的物料比例。在本工作范围内，支路流量比例对RTD特性没有显著影响，只是与平均停留时间呈弱负相关。此外，自然对流的搅拌效应会增加平均停留时间，尤其是在强制流动较弱的情况下。分析表明，在设计水热反应器和工况时，有必要考虑自然对流、强制流动和反应器尺寸的匹配来控制RTD。

相变材料是一种高效的储热材料，在建筑节能、余热回收、电池热管理等多个领域有着广阔的应用前景。特别是无机水合盐相变材料，由于价格低廉、不易燃等优点，越来越受到研究人员的青睐。然而，无机水合盐相变材料在应用过程中仍然受到其相变温度、液相泄漏、过冷度大和相分离严重等方面的限制。本研究选择三水合醋酸钠作为基础无机相变材料，并通过使用各种功能添加剂改性，制备出具有良好热性能的新型形状稳定的复合相变材料。首先，使用了乙酰胺来调节三水合醋酸钠的熔点，制备出三水醋酸钠-乙酰胺二元混合物。然后，将二元混合物与膨胀石墨复合，合成了一种新型形状稳定的复合相变材料。系统地研究了制备得到的复合相变材料的热物理性质。并对得到的形状稳定复合相变材料的微观形貌和化学结构进行了表征和分析。结果表明，乙酰胺可以有效降低三水合醋酸钠的熔点。使用18%乙酰胺和12%膨胀石墨改性获得的形状稳定复合相变材料，具有良好的定形效果和热物理性能：其过冷度仅为1.75°C，熔化温度为40.77°C，潜热为151.64 kJ/kg，热导率高达1.411 W/(mŸK)。此外，所制备的形状稳定复合相变材料在经历50次加速熔化-凝固循环后，表现出良好的热可靠性。

压缩机在近临界区的低功耗是实现超临界CO₂布雷顿循环高效运行的关键因素。在压缩机的数值模拟中，在临界点附近CO₂物性的快速变化使得冷凝现象难以捕捉。本文研究了流体物理性质对冷凝现象的影响。首先比较了SRK EOS(状态方程)、PR EOS和SW EOS中CO₂的物理性质差异，然后对喷嘴和压缩机进行了仿真。结果表明，3种EOSs预测的凝结位置基本一致。与SW EOS相比，PR和SRK EOS预测的最大凝结质量分数差异分别为5.7%和11.5%，总压比差异分别为0.3%和3.8%。结果表明，PR EOS可用于工程实际的数值模拟。由于其物性计算结果更接近实际物性，而物性变化更平缓，具有相当的精度和数值稳定性。

循环工质对脉动热管传热特性具有重要影响。本文采用实验方法研究了以相变微胶囊（MEPCM）悬浮液（质量浓度为0.5%、1%）和超纯水为工质的脉动热管传热特性。结果表明，MEPCM 悬浮液能够提高脉动热管的运行稳定性。当倾角为90°时，蒸发端温度相较于超纯水降低，且蒸发端温度随MEPCM悬浮液浓度的增加而降低。脉动热管的传热性能与倾角呈正相关，90°时最优，而加热功率增大，倾角的不利作用减小。倾角为90°，以质量浓度为1%的MEPCM悬浮液为工质的脉动热管传热热阻最低，超纯水次之，质量浓度为0.5%的MEPCM悬浮液脉动热管传热热阻最高；倾角为60°和30°时，重力对工质流动的促进作用减弱，由于MEPCM悬浮液具有较高的粘度，超纯水脉动热管传热热阻最低；倾角为60°时，加热功率小于230 W时，质量浓度为0.5%的MEPCM悬浮液脉动热管热阻低于质量浓度为1%时的热阻；加热功率为230-250 W之间时，MEPCM悬浮液脉动热管的热阻趋于一致；加热功率大于270 W时，质量浓度为1%的MEPCM悬浮液脉动热管热阻低于质量浓度0.5%时的热阻。

本研究基于COMSOL多物理场仿真软件，对液态金属锂在真空自由分子流状态下的蒸发过程进行了建模和数值模拟。通过系列研究，分析了锂原子在蒸发过程中的运动状况。根据现有的液态金属锂饱和蒸汽压实验值，得到了液态金属锂在600 K-900 K范围内饱和蒸汽压与温度的关系。建立了二维对称模型(3.5 mm×20 mm)，分别模拟了750 K、780 K、800 K、810 K、825 K和850 K壁温下液态锂的瞬态蒸发过程。研究了温度、蒸发系数、背压和长径比对蒸发过程的影响，分析了蒸发过程中分子通量和压力的变化趋势及原因。同时，模拟了变壁温条件下的蒸发过程。本研究使液态锂在真空分子流中的蒸发过程更加清晰，为空间反应堆和核聚变相关领域提供了理论支持。

针对分布式供能的市场开发了2MW的燃气轮机，本燃机采用压比位7：1的径流式涡轮。在本文中，研究了各种几何尺寸变化对涡轮性能的影响，其中包括叶轮的叶尖间隙、叶背间隙。除此之外，导风轮深切以及排风轮尾缘导圆的影响也进行了相关研究。最终，与分体式叶轮相关的几何特征也进行了相关分析。这些几何特征的分析方法主要采用计算流体力学的方法。部分的试验数据与整机测试中的性能数据进行了对比和验证。结果表明，对于本文的这种高落压比涡轮而言，排风轮的径向叶尖间隙、导风轮的轴向叶尖间隙，甚至包括深切导风轮的轮背间隙都对性能几乎没有影响。在全部的算例中，1%的间隙改变，仅仅导致约0.1%的性能恶化。这一发现与已有的低压比叶轮的结果十分不一致，这也意味着对于高压比叶轮存在不同的物理机理。

Compressed Air Energy Storage (CAES) is one of the methods that can solve the problems with intermittency and unpredictability of renewable energy sources. A side effect of air compression is a fact that a large amount of heat is generated which is usually wasted. In the development of CAES systems, the main challenge, apart from finding suitable places for storing compressed air, is to store this heat of compression process so that it can be used for heating the air directed to the expander at the discharging stage. The paper presents the concept of a hybrid compressed air and thermal energy storage (HCATES) system, which may be a beneficial solution in the context of the two mentioned challenges. Our novel concept assumes placing the thermal energy storage (TES) system based on the use of solid storage material in the volume of the post-mining shaft forms a sealed air pressure reservoir. Implementation of proposed systems within heavily industrialized agglomerations is a potential pathway for the revitalization of post-mine areas. The potential of energy capacity of such systems for the Upper Silesian region could exceed the value of 10 GWh. In the paper, the main construction challenges related to this concept are shown. The issues related to the possibility of storing air under high pressure in the shaft from the view of the rock mass strength are discussed. The overall concept of the TES system installation solution in the shaft barrel is presented. The basic problems related to heat storage in the cylindrical TES system with a non-standard structure of high slenderness are also discussed. The numerical calculations were based on the results of experiments performed on a laboratory stand, the geometry of which is to reflect the construction of a TES tank in a post-mining shaft. The article presents the results of numerical analysis showing the basic aspects related to difficulties that may occur at the construction stage and during the operation of the proposed HCATES system. The paper focuses on the methodology for determining the energy and exergy efficiency of a section of a Thermal Energy Storage tank, and presents the differences in the performance of this tank depending on its geometric dimensions, which are determined by the different sizes of mine shafts.

喷射式制冷循环在复叠/复合循环中具有较广阔的应用潜力，可以通过去除或回收主循环的热量以提高系统的整体性能，同时喷射式制冷循环具有结构简单、成本低等优势。本文主要对应用于复叠式制冷系统中的喷射式制冷循环进行了研究，优化了系统工作工况，设计并研制了高蒸发温度、宽工况下的喷射制冷实验系统并开展了相关实验，分析获得了工作参数对喷射器及喷射式制冷系统性能的影响。本研究的实验及分析结果将为喷射式制冷循环在复叠/复合式制冷系统中的应用及工况优化提供重要依据。

Oxidation of acetylene (C2H2) has been investigated in a high-pressure jet-stirred reactor (HP-JSR) with equivalence ratios Φ=0.5, 1.0, 2.0 and 3.0 in the temperature range of 650 K–900 K at 1.2 MPa. 18 products and intermediates were analyzed qualitatively and quantitatively by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Generally, with Φ increasing, the production of intermediates increases significantly. CH₄, C₂H₄, C₂H₆, C₃H₆ and C3H8 were important intermediates, which were formed abundantly at Φ=3.0. Sufficient light hydrocarbon intermediates could be an important reason for significant formation of cyclopentadiene, benzene, toluene and styrene at Φ=3.0. A detailed kinetic mechanism consisting of 299 species and 2041 reactions has been developed with reasonable predictions against the present data and previous results obtained at 0.1 MPa. According to flux and sensitivity analysis, H and OH radicals play important roles in the consumption of C₂H₂. The combinations among light hydrocarbons and their free radicals are the main generation pathways of aromatics. C₃H₃, IC₄H₅ and AC3H5 are important precursors for the formation of aromatics. By comparing the results of atmospheric pressure and high pressure, it can be found that increasing the pressure is conducive to fuel consumption and aromatics generation.

Infrared thermography, velocity and impingement pressure measurements alongside numerical modelling are used in this study to resolve (heated) surface temperature distributions of turbulent swirling impinging jets for two Reynolds numbers (Re=11 600 and 24 600). Whilst building upon earlier discoveries for this same geometry, this paper provides three new contributions: (1) identifying the role of impingement distance (H/D) as a deciding factor in the trade-off between more efficient heat transfer (at high swirl numbers) and achieving better substrate temperature uniformity (lower gradients), (2) developing correlations to predict Nusselt number for swirling and non-swirling cooling jets, and (3) predicting the underlying mixing field in these jets and its interplay with the thermal distributions resolved.
Results indicate substrate temperature uniformity varies based on H/D and swirl intensity (S) with a significant level of thermal non-uniformity occurring in near-field impingement (H/D=1) at stronger swirl (S=0.59 and 0.74). Four correlations describing the effects of S, Re, and H on the average heat transfer and stagnation heat transfer are developed and yield accuracies of 8% and 12%, respectively. Flow recirculation near the impingement surface is predicted at H/D=1 for stronger swirl jets which disappears at other substrate distances. The peak wall shear stress reduces and the flow impingement becomes radially wider at higher H/D and S. Stronger turbulence or eddy viscosity regions for non-swirling jets (S=0) are predicted in the shear layer and entrainment regions at  H/D=1, but such turbulence is confined to the impingement and wall jet regions for strongly swirling flows.

冷凝温度是决定有机朗肯循环性能的关键参数之一。在设定有机朗肯循环的冷凝温度时，有必要考虑工质本身的差异。在本研究中，使用温熵图来描述工质的差异。定义了温熵（T-s）图中干工质和等熵工质的三个区域，即表示循环净输出功的区域（A1）、表示卡诺循环净功的区域（A）和表示冷凝特性的过热区曲边三角形（A2）。在此基础上，计算A2与A1的比率和A1与A的比率。获得了上述两个比率的对数平均差，以确定有机朗肯循环中使用的66种干/等熵工质的可操作理想冷凝温度。研究结果表明，大多数干工质和等熵工质的可操作理想冷凝温度在305K至310K之间。本文工作将有助于有机朗肯循环系统的设计。

为有效拓宽多旋流分级燃烧室高空条件下的稳定工作边界，在常温和海拔0-12km的低压条件下实验研究了模型燃烧室的点火和贫油熄火性能，并采用数值模拟方法获得了不同低压条件下分级燃烧室的冷态流场。实验结果表明，随海拔高度的升高，最小点火油气比和贫油熄火油气比迅速增大；随着旋流器压降由1%升高至3%，点火和贫油熄火性能逐渐改善。高速相机记录的火焰演化过程表明，稳定燃烧状态下的时均火焰形态在不同压降下类似，火焰亮度沿轴向分为“暗-亮-暗”三层，临近熄火时火焰收缩至预燃级出口，并伴随火焰发光强度的大幅减弱。数值模拟结果表明，随着空气压力的降低，参与雾化和燃烧的空气质量流量大幅减少，旋流空气的气动力减弱，不利于空气雾化喷嘴的雾化和油气掺混，并最终导致点熄火性能的恶化。