2024年, 第33卷, 第2期 刊出日期：2024-02-26
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热科学学报. 2024, 33(2): 395. https://doi.org/10.1007/s11630-024-1957-5
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热科学学报. 2024, 33(2): 396-407. https://doi.org/10.1007/s11630-024-1954-8热二极管作为一种可以降低建筑物能耗和提高电动汽车电池散热的重要传热元件，其优点在于可以使热量单向流动。相较于其他类型的热二极管，在设计、材料和工作条件等各种因素的影响下，对流式热二极管在预期应用中能表现出最佳的热整流效果。本研究基于相变传热机制，提出了一种新型带有毛细芯的对流式热二极管。这种设计巧妙的利用了毛细芯提供的毛细力和重力，提高了所设计的对流式热二极管的单向传热性能。通过实验研究了充液比对热二极管传热性能的影响，实验结果与理论分析结果吻合良好。研究结果表明，当充液比为140%时，带有毛细芯的热二极管在较低的加热功率下有较大的热整流比，并且当热二极管的加热功率为40 W时，热二极管的最大热整流比为 21.76。
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热科学学报. 2024, 33(2): 408-421. https://doi.org/10.1007/s11630-023-1776-0This study evaluates the effectiveness of phase change materials (PCMs) inside a storage tank of warm water for solar water heating (SWH) system through the theoretical simulation based on the experimental model of S. Canbazoglu et al. The model is explained by five fundamental equations for the calculation of various parameters like the effectiveness of PCMs, the mass of hot water, total heat content, and duration of charging. This study simulated eleven PCMs to analyze their effectiveness like Sodium hydrogen phosphate dodecahydrate (SHPD), OM 37, N-Eicosane (NE), Lauric acid (LA), Paraffin wax (PW), OM 48, Paraffin wax C20-33 (PW-C20-33), Sodium acetate trihydrate (SAT), Palmitic acid (PA), Myristic acid (MA), and Stearic acid (SA). Among all PCMs, the SHPD has found the highest value of effectiveness factor of 3.27. So, it is the most recommended PCM for the storage tank of the SWH system. The study also includes the melt fraction analysis of all enumerated PCMs corresponding to container materials of stainless steel, glass, aluminum mixed, tin, aluminum, and copper. This melt fraction analysis is performed by making a coding program in the FORTRAN programming language. Through the analysis, copper container material is found to have high melting rate for all PCMs so it is superior to other container materials.
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热科学学报. 2024, 33(2): 422-434. https://doi.org/10.1007/s11630-024-1910-7由于相变材料导热性差，潜热储热系统的储热性能不佳。本文采用一种结合矩形和三角形翅片的新型指针形翅片对储能罐内相变材料的熔化过程进行了数值模拟，并研究了翅片几何参数对储热性能的影响。结果表明，与裸管和矩形翅片罐相比，指针形翅片罐中相变材料的熔化时间分别缩短了64.2%和15.1%。三角形翅片的尖端离热壁越近，传热效率就越好。三角形翅片的最佳高度约为8 mm。将指针形翅片的数量从4个增加到6个和从6个增加到8个，可分别减少16.0%和16.7%的熔化时间。然而，将翅片数量从8个增加到10个只会缩短8.4%的熔化时间。当翅片无量纲长度从0.3增加到0.5，从0.5增加到0.7时，熔化时间分别缩短了17.5%和13.0%。但当翅片无量纲长度从0.7增加到0.9时，熔化时间仅缩短了2.9%。研究结果对储热系统的优化设计具有一定的参考价值。
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热科学学报. 2024, 33(2): 435-456. https://doi.org/10.1007/s11630-024-1925-0Present work investigates the heat transfer and melting behaviour of phase change material (PCM) in six enclosures (enclosure-1 to 6) filled with paraffin wax. Proposed enclosures are equipped with distinct arrangements of the fins while keeping the fin’s surface area equal in each case. Comparative analysis has been presented to recognize the suitable fin arrangements that facilitate improved heat transfer and melting rate of the PCM. Left wall of the enclosure is maintained isothermal for the temperature values 335 K, 350 K and 365 K. Dimensionless length of the enclosure including fins is ranging between 0 and 1. Results have been illustrated through the estimation of important performance parameters such as energy absorbing capacity, melting rate, enhancement ratio, and Nusselt number. It has been found that melting time (to melt 100% of the PCM) is 60.5% less in enclosure-2 (with two fins of equal length) as compared to the enclosure-1, having no fins. Keeping the fin surface area equal, if the longer fin is placed below the shorter fin (enclosure-3), melting time is further decreased by 14.1% as compared to enclosure-2. However, among all the configurations, enclosure-6 with wire-mesh fin structure exhibits minimum melting time which is 68.4% less as compared to the enclosure-1. Based on the findings, it may be concluded that fins are the main driving agent in the enclosure to transfer the heat from heated wall to the PCM. Proper design and positioning of the fins improve the heat transfer rate followed by melting of the PCM in the entire area of the enclosure. Evolution of the favourable vortices and natural convection current in the enclosure accelerate the melting phenomenon and help to reduce charging time.
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热科学学报. 2024, 33(2): 457-468. https://doi.org/10.1007/s11630-023-1824-9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。
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热科学学报. 2024, 33(2): 469-478. https://doi.org/10.1007/s11630-023-1828-5Heat storage properties of phase change materials (PCMs) are essential characteristics that perform a key role in thermal heat energy storage systems. The thermal properties of PCMs can be improved by developing metal foam/PCM composites. The addition of metal foam in PCMs has a significant effect on the thermal characteristics of PCMs. In this paper, the heat storage properties of two different metal foam/PCM composites were experimentally examined. The behavior of paraffin in metal foam (copper and iron-nickel)/paraffin composites concerning pure paraffin at a constant heat flux of 1000 W/m2 in three directions simultaneously (x, y, and z) was studied. Paraffin was infiltrated into copper and iron-nickel foams to develop composite materials which resulted in enhancing the thermal conductivity of the paraffin. A comparative analysis is made on the heat storage properties of paraffin in copper and iron-nickel foams/paraffin composites. Inner temperature distribution during the phase transition process is experimentally evaluated. This comparison indicates that temperature uniformity in copper foam/paraffin composite is better than in iron-nickel foam/paraffin composite and pure paraffin at the same heat flux. Experimental results show that at heat flux of 1000 W/m2, the heat storage time for copper foam/paraffin composite is 20.63% of that of iron-nickel foam/paraffin composite.
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热科学学报. 2024, 33(2): 479-490. https://doi.org/10.1007/s11630-024-1921-4氯盐作为高温热能储存( TES )介质在聚光太阳能发电系统中具有巨大的应用潜力。为了进一步拓宽三元氯盐的工作温度，提高其储能密度，本研究选择LiCl、KCl和CaCl2作为储能材料。基于Factsage开发了LiCl - KCl - CaCl2三元氯化盐，其质量分数分别为37.85 - 53.38 - 8.77、30.90 - 13.82 - 55.28和1.78 - 18.61 - 79.61 %，对应的熔化温度( Tm )分别为340.93、433.57和626.85°C，其对应组分分别命名为盐1，盐2，盐3。由于，盐3熔点过高，实验过程中不予考虑。DSC测试结果表明，盐1和盐2的实际熔点与Factsage软件预测的熔点仅相差0.46 %和1.64 %。同时，采用模拟和实验手段对比了盐1和盐2的质量损失，模拟结果表明，在650°C以下时，盐1的蒸气压几乎不变。同时，实验结果表明，在空气气氛下，盐1的上限工作温度为650°C。此外，三元氯盐在短期循环后仍表现出优异的热性能，揭示了这些良好的热性能使其在高温热能存储系统中具有广阔的应用前景。
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热科学学报. 2024, 33(2): 491-500. https://doi.org/10.1007/s11630-023-1895-7Thermal energy storage (TES) systems use solar energy despite its irregular availability and day-night temperature difference. Current work reports the thermal characterizations of solar salt-based phase change composites in the presence of graphene nanoplatelets (GNP). Solar salt (60:40 of NaNO3:KNO3) possessing phase transition temperature and melting enthalpy of 221.01°C and 134.58 kJ/kg is proposed as a phase change material (PCM) for high-temperature solar-based energy storage applications. Thermal conductivity must be improved to make them suitable for widespread applications and to close the gap between the system needs where they are employed. GNP is added at weight concentrations of 0.1%, 0.3%, and 0.5% with solar salt using the ball milling method to boost its thermal conductivity. Morphological studies indicated the formation of a uniform surface of GNP on solar salt. FTIR spectrum peaks identified the physical interaction between salt and GNP. Thermal characterization of the composites, such as thermal conductivity, DSC and TGA was carried out for the samples earlier and later 300 thermal cycles. 0.5% of GNP has improved the thermal conductivity of salt by 129.67% and after thermal cycling, the enhancement reduced to 125.21% indicating that thermal cycling has a minor impact on thermal conductivity. Phase change temperature decreased by around 2.32% in the presence of 0.5% GNP and the latent heat reduced by 4.34% after thermal cycling. TGA thermograms depicted the composites initiated the weight loss at around 550°C after which it was rapid. After thermal cycling, the weight loss initiated at ~40°C lower compared to pure salt, which was found to be a minor change. Thermal characterization of solar salt and GNP-based solar salt composites revealed that the composites can be used for enhanced heat transfer in high-temperature solar-based heat transfer and energy storage applications.
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热科学学报. 2024, 33(2): 501-508. https://doi.org/10.1007/s11630-024-1919-y本文设计并研究了一种用于聚光太阳能发电（CSP）的新型三元共晶盐Na2CO3-Li2CO3-LiF。利用 FactSage 软件预测了 Na2CO3-Li2CO3-LiF 的共晶点及组分。通过一系列实验，对该共晶盐的微观结构、热物理性质和热稳定性进行了研究。当质量比为 57:32:11 wt%时，共晶盐具有优异的蓄热性能，熔点为 426.8°C，其潜热为 413 J/g。同时共晶盐展现出优异的热稳定性，在 600 摄氏度时的重量损失仅为 0.8%。
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热科学学报. 2024, 33(2): 509-521. https://doi.org/10.1007/s11630-023-1859-yThermal energy storage (TES) is of great importance in solving the mismatch between energy production and consumption. In this regard, choosing type of Phase Change Materials (PCMs) which are widely used to control heat in latent thermal energy storage systems, plays a vital role as a means of TES efficiency. However, this field suffers from lack of a comprehensive investigation on the impact of various PCMs in terms of exergy. To address this issue, in this study, in addition to indicating the melting temperature and latent heat of various PCMs, the exergy destruction and exergy efficiency of each material are estimated and compared with each other. Moreover, in the present work the impact of PCMs mass and ambient temperature on the exergy efficiency is evaluated. The results proved that higher latent heat does not necessarily lead to higher exergy efficiency. Furthermore, to obtain a suitable exergy efficiency, the specific heat capacity and melting temperature of the PCMs must also be considered. According to the results, LiF-CaF2 (80.5%:19.5%, mass ratio) mixture led to better performance with satisfactory exergy efficiency (98.84%) and notably lower required mass compared to other PCMs. Additionally, the highest and lowest exergy destruction are belonged to GR25 and LiF-CaF2 (80.5:19.5) mixture, respectively.
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热科学学报. 2024, 33(2): 522-536. https://doi.org/10.1007/s11630-023-1909-5Phase change materials (PCMs) designate materials able to store latent heat. PCMs change state from solid to liquid over a defined temperature range. This process is reversible and can be used for thermo-technical purposes. The present paper aims to study the thermal performance of an inorganic eutectic PCM integrated into the rooftop slab of a test room and analyze its potential for building thermal management. The experiment is conducted in two test rooms in Antofagasta (Chile) during summer, fall, and winter. The PCM is integrated into the rooftop of the first test room, while the roof panel of the second room is a sealed air cavity. The work introduces a numerical model, which is built using the finite difference method and used to simulate the rooms’ thermal behavior. Several thermal simulations of the PCM room are performed for other Chilean locations to evaluate and compare the capability of the PCM panel to store latent heat thermal energy in different climates. Results show that the indoor temperature of the PCM room in Antofagasta varies only 21.1°C±10.6°C, while the one of the air-panel room varies 28.3°C±18.5°C. Under the experiment’s conditions, the PCM room’s indoor temperature observes smoother diurnal fluctuations, with lower maximum and higher minimum indoor temperatures than that of the air-panel room. Thermal simulations in other cities show that the PCM panel has a better thermal performance during winter, as it helps to maintain or increase the room temperature by some degrees to reach comfort temperatures. This demonstrates that the implementation of such PCM in the building envelope can effectively reduce space heating and cooling needs, and improve indoor thermal comfort in different climates of Chile.
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热科学学报. 2024, 33(2): 537-547. https://doi.org/10.1007/s11630-022-1651-4Dodecyl alcohol (DDA) is a promising solid-liquid phase change material (PCM) due to its favorable latent heat storage (LHS) characteristics. However, the leakage issue of PCM in a melted state during the heating period and low thermal conductivity restricts its utilization potential in thermal energy storage (TES) practices. Within the same context, the present work aims to overcome the leakage issue and improve the thermal conductivity of the DDA. With this in mind, a novel leak-proof layered double hydroxide (LDH)/DDA composite PCM is proposed through a solution-based impregnation method. The leak-proof impregnation ratio of the DDA impregnated within the cavities of the synthesized Al/Fe-LDH was determined to be 60%. Detailed morphological, physicochemical, and thermal properties of the fabricated composite were studied by scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, differential scanning calorimetry (DSC), thermalgravimetric analysis (TGA), and thermal cycling study. The results show that the LDH/DDA composite has a suitable phase change temperature (about 20°C) for passive solar thermal management of building envelopes. This composite PCM showed high LHS enthalpy (about 136 J/g), good thermal stability, and cycling LHS reliability. It also showed nearly 152% higher thermal conductivity compared to that of pure DDA, ultimately reducing the melting and solidification time of the pure DDA by 44.9% and 45.5%, respectively.
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热科学学报. 2024, 33(2): 548-563. https://doi.org/10.1007/s11630-023-1841-8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。
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热科学学报. 2024, 33(2): 564-577. https://doi.org/10.1007/s11630-024-1860-0相变微胶囊悬浮液（MEPCMS）由于胶囊颗粒的固液相变吸收潜热，成为高热流密度热管理的潜在工质。本文采用基于欧拉-拉格朗日方法的离散相模型(DPM)对粒径为5 μm的MEPCMS在矩形细小通道内的对流换热特性进行了数值研究。结果表明，MEPCMS颗粒在流动传热性能主要受控于曳力和热泳力的作用；热泳力会驱动颗粒从高温区向低温区迁移，进而影响颗粒分布和相变过程。颗粒相变导致悬浮液的当量比热容发生变化，进而导致MEPCMS局部换热性能的变化。当近壁面胶囊开始融化时， Nux随着增加；近壁面胶囊完全融化时，Nux达到最大，随后开始下降；当胶囊基本融化完时，Nux达到最低，随后恢复到接近纯基液的充分发展值。MEPCMS的换热性能受流体入口温度、流体入口速度以及MEPCM颗粒质量浓度的综合影响。当Tin=293.15 K, v=0.15 m·s-1, cm=10%时，ΔTw的最大下降率为23.98%。
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热科学学报. 2024, 33(2): 578-590. https://doi.org/10.1007/s11630-024-1922-3本研究主要利用相变材料(PCM)在其相变过程中吸收或释放的大量潜热来调节电池充放电过程中的表面温度波动，以期将电池保持在最佳工作温度范围内。通过在圆柱形电池周围包裹PCM，研究PCM厚度和相变温度对电池温度的影响。为提高相变材料的导热性能，在其中加入膨胀石墨(EG)制备成复合相变材料(CPCM)，研究膨胀石墨不同质量占比对电池温度和CPCM利用率的影响。结果表明，增加PCM厚度可延长温度控制时间，但影响有限。不同相变温度的PCM可将电池温度控制在不同范围内。高温环境时不宜利用相变温度较低的PCM对电池进行温度控制。添加EG可提高PCM导热性能，从而进一步降低电池温度。当CPCM中EG质量占比为6%时，其对电池的有效控温时间延长了11 min，较单一PCM提升了28%。在基于PCM的电池热管理系统(BTMS)中，CPCM的利用率较高，同时可实现蓄热和导热之间的平衡。
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热科学学报. 2024, 33(2): 591-601. https://doi.org/10.1007/s11630-023-1915-7采用瞬态平面源实验和XCT模拟的方法，研究了熔盐泄漏后储热系统熔盐罐内地基材料的热物性。研究了不同粒径材料的微观结构、导热性能和耐压性能。三种孔隙率分别为30.1%、30.7%和31.2%的工况下，由瞬态平面源实验测得的导热系数分别为0.49 W/(m∙K)、0.48 W/(m∙K)和0.51 W/(m∙K)。这三种工况的导热系数模拟结果分别为0.471 W/(m∙K)、0.482 W/(m∙K)和0.513 W/(m∙K)。模拟结果与实验测量结果的误差低至1.2%，这在一定程度上验证了实验和仿真结果的可靠性。熔盐泄漏前导热系数为0.097 ~ 0.129 W/(m∙K)、孔隙率为71.6 ~ 78.9%，熔盐泄漏后孔隙率降低50%以上，导热系数提高4 ~ 5倍。这种导热系数的显著增加对太阳能电站储罐基础的安全运行、结构设计和建模都有很大的影响。
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热科学学报. 2024, 33(2): 602-610. https://doi.org/10.1007/s11630-024-1936-x旋转不稳定是一种复杂的流动现象，随压气机气动负荷的不断提高，其诱发的叶片非同步振动问题已成为压气机设计面临的重要挑战。本研究旨在了解跨声速轴流压气机转子旋转不稳定引发的叶片非同步振动现象。实验中，叶片的非同步振动和气流激励通过应变片和壁面机匣压力脉动传感器获取，使用全环非定常数值模拟揭示了压气机内非同步气流激励的产生机制。结果表明：第一级转子叶片呈现一阶弯曲模态下的非同步振动，非同步振动的发生伴随着压力脉动的急剧增加，其幅值可达20%水平。当叶片处于大幅值振动时，非定常气流激励频率将锁定至叶片结构的固有频率，数值预测的非同步气流激励频率与实验结果吻合较好。周向不稳定流动气流扰动的主要模态数约为叶片数的47%，其周向尺度占据2～3栅距，叶尖泄漏流和吸力面分离涡相互作用使得叶尖不稳定涡在流向发生振荡，是引起叶片非同步振动的主要原因。
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热科学学报. 2024, 33(2): 611-624. https://doi.org/10.1007/s11630-024-1908-1本文通过数值方法研究了跨声速压气机叶栅内部多孔吸气对流动分离控制的影响。所研究抽吸孔分别以单排、双排和三排交错方式布置于叶栅吸力面上。针对每种抽吸方案，分别研究了5种抽吸压力比在进口马赫数为1.0条件下的影响。结果表明，多孔吸气可以显著改善叶栅的气动性能。对于单排方案，总压损失最大相对减小量为57%。对于双排和三排方案，存在一个最佳吸气压力比1.0。总压损失的最大相对减小量分别为68%和75%。边界层发展的有效控制是降低叶栅内部总压损失的主要原因。抽吸孔诱导的新局部超声速区是控制边界层发展的关键因素。抽吸孔侧向吸气诱导的涡旋为延迟流动分离提供了另一种机制。增加吸气孔数量可以产生多个局部超声速区，从而减小边界层需要承受的逆压梯度范围，而这也是多排抽吸孔在流动分离控制方面表现更好的原因。
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热科学学报. 2024, 33(2): 625-647. https://doi.org/10.1007/s11630-024-1890-7碳排放问题日益引起人们的关注，高温领域的热能传递效率问题成为关注焦点。高温热管(HTHP)是一种工作温度高的高效传热装置，在太阳能热电、高温烟气余热回收、工业炉窑、核工业和航空等领域有广泛应用。本文从影响高温热管传热性能的因素、高温热管的仿真及理论分析，这两方面对近30年的相关文献进行了汇总分析。首先介绍了工质、热管结构和毛细芯结构对其传热性能的影响研究，并对每个方面的较优研究成果进行了一定的介绍；然后回顾了高温热管的数值模拟中所采用过的一些重要假设，对传热极限的一些理论研究结果；最后基于文献分析结果，对高温热管未来的研究方向尝试提出了一些建议。希望本文对高温热管领域从业者有一定的参考意义。
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热科学学报. 2024, 33(2): 648-657. https://doi.org/10.1007/s11630-024-1930-3在电子设备冷却系统中，本工作提出了一种将遗传算法与自适应深度学习相结合的三维数据驱动优化设计模型，实现了碳/碳复合材料结构中的传热定向调控和优化。随优化进行的自适应过程使得深度学习模型对优化前缘结构的温度预测更接近真实值。利用该模型对三维复合结构中孔隙和高导热碳纤维的分布进行了优化，结果表明，当构建结构的孔隙率在3%至11%之间变化时，优化结构中的电子器件表面温度比初始结构低19.1-27.5%。电子器件的表面温度随着孔隙率的增加而增加。高导热碳纤维电子器件表面附近，孔隙分布于结构中间区域将使热疏导复合结构表现出最优散热能力。此外，本优化模型的计算时间缩减为传统遗传算法的十分之一。
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热科学学报. 2024, 33(2): 658-674. https://doi.org/10.1007/s11630-024-1943-y在传统的槽式太阳能集热器中，由于线聚焦的局限性，聚光能流密度不均匀，导致集热管在径向方向存在较大的温度梯度，在实际工程应用中容易引起弯曲爆管、热效率降低等一系列问题。针对这个问题，本论文从改进聚光均匀性和强化内部传热的思路出发，提出了一种新型集热器，利用二次匀光和管内螺旋导流的协同作用，改善了集热器的热变形并提高效率。通过构建三维的光-热-结构多物理场耦合模型，探究了不同工况下新型集热器的聚光能流、温度、热变形、热效率、损失以及压降等变化规律。随着螺距增加，集热器的热效率升高，同时也会导致显著的压降，因此选择最优螺距为1040 mm。结果表明，在典型工况下，高太阳辐照和低流速下新型接收器的径向温差减小了62.5 K，热变形减小了96%，热效率提高了1.2个百分点。提出的新型集热器为槽式太阳能集热器减少热变形，提高热效率等方面提供了理论和方法依据。
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热科学学报. 2024, 33(2): 675-695. https://doi.org/10.1007/s11630-024-1923-2蒸汽喷射器是余热回收系统中的关键部件。其性能决定了回收热量和系统效率。然而，较差的喷射器性能一直是系统应用的主要瓶颈。因此，本研究提出了一种利用计算流体动力学（CFD）技术、响应面法（RSM）和遗传算法（GA）来提高蒸汽喷射器性能的优化方法。首先，建立了均匀平衡模型（HEM）来模拟蒸汽喷射器中的两相流。然后，采用正交试验筛选对夹带率有显著影响的关键决策变量。接下来，使用RSM来拟合响应面回归模型（RSRM）。同时，揭示了几何参数相互作用对蒸汽喷射器性能的影响。最后，采用遗传算法求解RSRM的全局最优ER值。结果表明，RSRM对ER表现出良好的拟合（R2=0.997）。经RSM和GA优化后，喷射器的最大效率为27.94%，比初始喷射器的18.83%提高了48.38%。此外，在非设计条件下，优化后的喷射器效率平均提高了46.4%。总之，结果表明，CFD、RSM和GA的结合在两相蒸汽喷射器的优化设计中具有良好的可靠性和可行性。
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热科学学报. 2024, 33(2): 696-709. https://doi.org/10.1007/s11630-024-1948-6目前，针对石油烃污染场地的修复技术——原位热脱附技术存在能耗高的问题。掌握污染土壤的关键热物性参数（热导率、比热容和热扩散率）有助于准确模拟计算修复场地的热量传递和温度分布，进而指导工程上优化方案，以实现节能降碳。然而，目前鲜有关于石油烃污染土壤的此类数据报道。在本研究中，制备了干容重恒定而柴油（石油烃的代表物之一）质量浓度在0~20%之间的土壤样品，并在0~120 ℃的宽温度范围内测量和分析了其热导率、比热容和热扩散率的变化规律。实验结果表明，当柴油浓度低于1%时，柴油对土壤热导率的影响可忽略。当柴油浓度低于10%时，土壤的热导率与温度的变化趋势相同；当柴油浓度超过10%时，土壤热导率则与温度的变化趋势相反。各类土壤矿物的热导率通常随着温度的升高而增大，而柴油的热导率则随着温度的升高而减小，因此土壤矿物和柴油之间的竞争关系决定了柴油污染土壤的热导率随温度的变化趋势。无论柴油浓度如何变化，土壤的比热容均与温度的变化趋势相同，土壤的热扩散率则均与温度的变化趋势相反。显著性检验结果表明，与温度相比，柴油浓度对土壤热物性的影响更为显著。此外，对照实验的结果表明，含有相同质量浓度的柴油和某一烷烃的土壤样品的热导率的相对差异均低于10%，因此本研究中用柴油获得的土壤热物性变化规律可以类比推广到各类石油烃污染场地。基于三维分形和热阻分析，提出了一个理论预测模型，证实了柴油浓度对土壤热导率的影响。为了便于实际应用，以实验数据为基础，提出了以柴油浓度为自变量的土壤热导率线性回归模型。
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热科学学报. 2024, 33(2): 710-724. https://doi.org/10.1007/s11630-024-1928-x尽管人们在燃烧热声不稳定性研究方面做了大量努力，但在现代燃气轮机或航空发动机中成功抑制热声压力振荡仍然具有挑战性。本文通过大涡模拟研究了声衬对模型环形燃烧室纵向热声模态的影响。对于没有声衬的情况，模拟得到的自激纵向热声不稳定结果与实验得到的热声频率和模态结果非常吻合。随后，我们计算了三种不同声衬偏流速度下的环形燃烧室热声振荡特性。结果表明，燃烧室壁面声衬的存在不仅会影响声场，还会影响流场。当偏流速度较大时，会导致强烈的湍流波动，从而使得压力振荡出现间歇性。这表明流动波动和压力振荡之间的耦合在热声系统间歇性的动态过程中起着重要作用。通过进一步动力学分析，表明这种间歇性是由流场对火焰-声耦合的影响造成的。最后，我们采用了一种基于范德波尔（VdP）振荡器的低阶建模方法，通过加入随机强迫，以再现热声系统的演变特性。虽然与实际燃烧系统相比，该低阶模型较为简单，但它仍然有助于我们理解声衬在燃烧室中的抑制效果，以及应用这种装置的潜力。
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热科学学报. 2024, 33(2): 725-738. https://doi.org/10.1007/s11630-024-1947-7聚酯玻璃纤维塑料是一种由玻璃纤维和聚酯聚合物构成的热固性塑料，在高速列车上被广泛应用。研究其热解机理至关重要，因为它对燃烧特性和消防安全具有重要影响。目前，聚酯玻璃钢的动力学研究主要集中在利用Coats-Redfern方法推导理论动力学模型。然而，聚酯GFRP的热解过程复杂，上述理论模型无法准确描述热解机理。因此，本研究试图利用Sestak-Berggren (SB)模型方法来揭示热解过程中复杂的反应机理。基于热重分析，将聚酯玻璃钢的整个热解过程分为两个初级阶段。此外，还采用了无模型方法确定活化能和指前因子。结果表明，两个主要热解阶段的拟合经验模型分别为f(α)=(1–α)1.47·[–ln(1–α)]1.50和f(α)=(1–α)1.77·[–ln(1–α)]1.72。该经验模型的预测结果和实验数据具有较好的，表明该经验模型能够充分描述聚酯GFRP的热解过程。
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热科学学报. 2024, 33(2): 739-750. https://doi.org/10.1007/s11630-024-1870-y这项研究调查了一台大型二冲程低速船用柴油发动机在不同负荷下使用低硫重油（HFO）时的颗粒物（PM）排放情况。从发动机排气中原位采集了颗粒物样品，以确定其详细的物理和化学特性。利用透射电子显微镜图像（TEM）分析了颗粒的纳米结构和形态。结果表明，挥发性有机碳（OC）占重油颗粒的 80% 以上，并导致颗粒尺寸增大。低速机的热力学条件有利于形成挥发性有机成分。检测到大量空气动力学直径为 0.2 μm-0.5 μm 的球形碳质粒子，其内部含有疑似金属内核。也含有两个空气动力学直径峰值分别为 15 nm 和 86 nm的纳米尺寸粒子。不同发动机工况下重油粒子的形态差异反映了热力学因素对新生粒子至成熟石墨粒子的转化影响。本研究对于了解低硫重油颗粒物的排放特征并探索降低船舶颗粒物的排放途径具有重要价值。
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热科学学报. 2024, 33(2): 751-760. https://doi.org/10.1007/s11630-024-1938-8随着人们对水泥产业产生大规模二氧化碳排放的认知日益加深，相关领域的研究也在不断推进，温室气体的减排策略已经逐渐成为水泥生产中关注的焦点。在所有的减排策略中，应用生物质作为替代燃料被广泛应用于水泥生产过程中，以实现二氧化碳的减排。另外，由于水泥生产过程中不可避免地在高温条件下产生热力型氮氧化物，因此有必要开展生物质在水泥生产过程中的应用对氮氧化物排放影响的研究。使用三种生物质燃料和烟煤在立式管式炉试验台上研究了不同工况下的NO还原特性。结果表明，在通入气氛中的氧气浓度由1%增加到到9%的过程中，反应器中的反应时间从1425秒减少到555秒，这意味着氧浓度的增加会导致反应时间缩短，相应地，氮氧化物在烟气中的存留时间也会缩短，但在氧浓度从1%到9%变化的过程中，烟气中氮氧化物的峰值浓度从54 ppm上升到105 ppm。氧浓度的增加极大地减少了燃料对氮氧化物的还原能力。秸秆燃烧过程中氮氧化物的峰值浓度为456 ppm，约为煤的约7倍，这是由于秸秆中N含量较高所致。生料的添加对氮氧化物的还原具有抑制作用：添加生料后，燃料对氮氧化物的有效还原时间减少了约20%，但添加生料会使反应初期烟气的CO2浓度升高。
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热科学学报. 2024, 33(2): 761-778. https://doi.org/10.1007/s11630-024-1926-zThe current study is performed to find sustainable solutions for the future of transportation and environmental well-being. Both conventional methods and experimental design table (L16 Orthogonal Array) techniques have been employed to examine and optimize a diesel-powered engine’s operational and pollutant parameters. The L16 Orthogonal Array is obtained through Taguchi’s experimental design approach using Minitab 16 software. The experimental design incorporated three control variables, namely engine speed, fuel type, and engine load, each with four levels. The operational parameters, namely brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC), as well as the emission characteristics, including hydrocarbon (HC), carbon monoxide (CO), nitrogen oxide (NO), and smoke emissions, were acquired using the L16 orthogonal array (OA) and subsequently examined. The utilization of methodologies such as signal-to-noise (S/N) ratio and grey analysis was employed to determine the optimal operational state of the engine to achieve maximum performance while minimizing emissions.
The engine’s ideal state of operation, in terms of BTE and BSFC, was determined to be at 75% engine load, 1000 r/min engine speed, and using 10–4 (in vol) carbon nanotube incorporated 20% orange peel biodiesel (OPB20CNT100) blended fuel (A3-B1-C4). The study indicated that engine load significantly influenced BTE and BSFC, with 84.05% and 87.79% contribution factors, respectively. At 25% engine load, 1000 r/min, and OPB20CNT100 fuel (A1-B1-C4) CO, smoke, NO, and HC emissions were the lowest. Engine load affects emissions the most. Engine BSFC increased 3.10% and NO emissions 1.77%. BTE, CO, smoke, and HC emissions decreased by 1.9%, 12.29%, 47.05%, and 47.22%, respectively, at optimal operating conditions concerning diesel fuel. This study shows that Taguchi-Grey’s experimental design optimizes diesel engine operational and pollutant attributes. The outcomes revealed that orange peel biodiesel infused with CNT can replace diesel fuel in an environmentally friendly way. This alternative fuel could clean and improve transportation.
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热科学学报. 2024, 33(2): 779-792. https://doi.org/10.1007/s11630-024-1950-zBased on the optical engine, the ignition characteristics, combustion process and soot emission characteristics of diesel under different 2-Methylfuran (MF) atmospheres were investigated by high-speed photography and in-cylinder combustion analysis technology. The results show that at the same main injection timing, the ignition time of reactivity controlled compression ignition (RCCI) combustion mode is earlier than pure diesel combustion, and the ignition point is concentrated near the nozzle. Diesel acts as a spark plug to ignite the mixture, but the flame develops slowly in the early stages and the pressure in the cylinder rises slowly. Compared with pure diesel, RCCI combustion model has smaller peak values of in-cylinder pressure and heat release rate, shorter ignition delay period, earlier combustion phase and shorter combustion duration. At main spray time at 6°CA BTDC and 12°CA BTDC, with the increase of MF premixing ratio from 0 to 0.75, the peak cylinder pressure decreased by 19.6% and 26% respectively. In addition, with the increase of the MF heat value ratio, the area of KL factor > 1.5 in the combustion chamber decreased and the space integral natural luminescence (SINL) peak value decreased by 48.37%, and the soot formation rate and yield decreased significantly. However, when the MF heat value ratio was too large (75% of the total calorific value), the ignition delay period increased, and misfire occurred at the main injection timing of 0°CA BTDC. The RCCI mode of MF/diesel dual fuel has better stability, and better control effect can be obtained at different main injection timing.
