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研究目的：通过实验方法定量研究在相变材料较为剧烈的熔化传热过程中散热器倾斜角度的改变对其瞬时性能所产生的影响。创新要点：定量研究在倾斜角度从水平到垂直时,储能式散热器在脉冲式热负荷作用下瞬时性能的变化规律,并在所研究的工况范围内给出了最优的倾斜角度参考值。研究方法：采用电加热方法模拟电子器件所产生的热源,通过调节电压改变脉冲式热负荷的强度和作用时间,并根据热电偶测量所得的加热表面温度变化来表征储能式散热器的瞬时性能。重要结论：在一定的倾斜角度下工作,可以有效提升基于相变材料的储能式散热器的瞬时性能。在加热功率为40 W、以75℃为目标时,其有效保护时间的相对增长可达约67%。 相似文献
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Mo/Cu材料具有高导热系数和低热膨胀系数及良好的耐热性,因此被广泛用于封接材料、电触头材料和散热器材料.本文阐述了Mo/Cu材料传统制备工艺和新型Mo/Cu复合材料的制备工艺研究进展.同时对国内外最新研究进行了归纳总结,针对Mo/Cu材料应用的性能要求指出了今后发展的主要动向. 相似文献
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为研究微小孔径气体受限冲击射流的换热特性,采用电阻丝加热方形酚醛树脂薄板作为模拟发热芯片的换热表面,沿对角线均匀布置热电偶以采集表面温度分布。以3mm孔径的圆形单孔及1mm孔径两种不同排列的圆形多孔喷射板对发热面进行中低Re数的射流冲击换热实验．通过改变风数及高度孔径比等参数得到了批数的径向分布及驻点区的换热特性,为射流冲击换热在封装芯片冷却上的应用提供了实验基础。 相似文献
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Study on performance of a packed bed latent heat thermal energy storage unit integrated with solar water heating system 总被引：1，自引：0，他引：1
NALLUSAMY N. SAMPATH S. VELRAJ R. 《浙江大学学报(A卷英文版)》2006,7(8):1422-1430
INTRODUCTION Efforts of rational and effective energy man-agement, as well as environmental considerations, increase the interest in using renewable energy sources, especially solar energy. Because of discrep-ancy between the energy supply and demand in solar heating applications, a thermal energy storage (TES) device has to be used for the most effective utilization of the energy source. Energy storage combined with solar collectors and photovoltaic systems have been developed over the… 相似文献
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QIN Feng CHEN Jiang-ping ZHANG Wen-feng CHEN Zhi-jiu 《浙江大学学报(A卷英文版)》2007,8(2):197-204
INTRODUCTION Metal hydrides are special alloys which absorb and desorb hydrogen reversibly. At room temperature, metal hydrides could absorb as much hydrogen as liquid hydrogen of the same volume under much lower pressure and much higher temperature (Güther and Otto, 1999). Massive reaction heat is generated accompanying this reaction, which could be used for waste heat recovery, solar energy utilization and re-frigeration with no side effect to environment (Izhvanov et al., 1996). Con… 相似文献
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Investigation of heat sink of endothermic hydrocarbon fuels 总被引：2，自引：0，他引：2
Endothermic hydrocarbon fuels are advanced coolants for high-temperature structures of spacecraft. No data of tested-cooling-ability of endothermic fuels have been broadly discussed in literature. In this work a high-temperature flow calorimeter was designed, and the cooling capacity of six different hydrocarbon fuels were measured. Experimental results showed that these hydrocarbon fuels have capacity for cooling high-temperature structures, and that the cooling capacity of fuel N-l can reach 3.15 MJ/kg, which can nearly satisfy the requirement of thermal management for a Mach 3 cruise aircraft, whose heat sink requirement is about 3.5 MJ/kg. The endothermic velocity of hydrocarbon fuels was also measured by the calorimeter. 相似文献
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Seyed Sahand SEBTI Mohammad MASTIANI Hooshyar MIRZAEI Abdolrahman DADVAND Sina KASHANI Seyed Amir HOSSEINI 《浙江大学学报(A卷英文版)》2013,14(5):307-316
A comprehensive numerical study was conducted to investigate heat transfer enhancement during the melting process in a 2D square cavity through dispersion of nanoparticles. A paraffin-based nanofluid containing various volume fractions of Cu was applied. The governing equations were solved on a non-uniform mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid-liquid interface. The effects of nanoparticle dispersion in a pure fluid and of some significant parameters, namely nanoparticle volume fraction, cavity size and hot wall temperature, on the fluid flow, heat transfer features and melting time were studied. The results are presented in terms of temperature and velocity profiles, streamlines, isotherms, moving interface position, solid fraction and dimensionless heat flux. The suspended nanoparticles caused an increase in thermal conductivity of nano-enhanced phase change material (NEPCM) compared to conventional PCM, resulting in heat transfer enhancement and a higher melting rate. In addition, the nanofluid heat transfer rate increased and the melting time decreased as the volume fraction of nanoparticles increased. The higher temperature difference between the melting temperature and the hot wall temperature expedited the melting process of NEPCM. 相似文献
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通过对晋城市巴公污水处理厂工艺改进前后两年同期运行数据的对比发现：COD去除率比较稳定,但在问一水温奈件下,技改后的C01）去除率略高于技改前;技改后NH3-N去除率2009年前半年有一定提高,后半年效果不明显,但出水总氯浓度有所降低;污泥负荷不稳定,相同污泥负荷条件下,技改后的NH3-N去除率高于技改前基于对主要影响因子的分析,建议在厌氧段前增设缓冲池稳定进水水质,提高碳氛比,在曝气池前加加热池、用废弃蒸汽或电加热等手段增强保温等措施、 相似文献
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针对废弃热量利用率低的问题,深入研究喷射制冷循环系统的工作原理和主要的内部结构,对喷射制冷循环系统的工作过程进行建模分析,得出系统中主要工作参数之间的数学关系。然后引入蒸汽压缩制冷原理,设计一个增压喷射制冷循环系统,对系统的性能特点进行详细分析,并给出在不同现实需求下的改进优化策略。测试结果表明设计的增压喷射制冷循环系统可以提高低品味的热量的利用率。 相似文献
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Flow visualization and hot-wire measurement techniques were combined to investigate the influence of the size and number of tabs on jet flow field and vortex structure generation mechanism. Streamwise vortices generated by the tabs of different sizes and numbers were ob- served from the flow visualization images. Combined with flow visualization, hot-wire measurement gave a quantitative insight of the effect of various tabbed jet flows. Instantaneous two-component velocity signals （longitudinal and transverse velocity components） at different cross sections along radius direction and streamwise direction with different tabbed jet nozzles were measured using hot-wire anemometer. Average flow field parameters of tabbed jet flow such as mean velocity, turbulence intensity, vorticity were analyzed and the effects of tabs with different sizes and numbers were compared with that of circular no-tab jet flow. It is revealed that the generation of a series of counter-rotating quasi-streamwise vortices, azimuthal vortices and double-row azi-muthal vortex are the reasons for mixing enhancement of tabbed turbulent jet flow. 相似文献
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王迅 《天津大学学报(英文版)》2004,10(1)
Thecriticalheatflux (CHF)intheforcedconvec tiveboilingwithawalljethasbeenstudied.KattoandIshii[1 ] measuredtheCHFofsaturatedwater,R1 1 3 ,andtrichloroethane (ρl/ ρg =2 0 3— 1 60 3)atatmosphericpressureforadownwardfacingplanewalljet,varyingthevelocityufrom 1 .5to 1 5m/sandtheheaterlengthLfrom 1 0to 2 0mm ,andproposedEq.(1 )topredicttheirCHFdata. qcoρghfgu=0 .0 1 6 4(ρl/ ρg) 0 .867(σρlu2 L) 1 / 3 (1 ) KattoandHaramura[2 ] ,further,haveextendedtheirvelocityrangefromu =1 .8t… 相似文献
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Ａｔｐｒｅｓｅｎｔ,Ｂｉ(2 2 2 3) /Ａｇｍｕｌｔｉｆｉｌａｍｅｎｔａｒｙｓｕｐｅｒ ｃｏｎｄｕｃｔｉｎｇｔａｐｅｓａｒｅｃｏｎｓｉｄｅｒｅｄｔｈｅｍｏｓｔｓｕｉｔａｂｌｅｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓ (ＨＴＳ)ｔｏｂｅａｐｐｌｉｅｄｔｏｓｕ ｐｅｒｃｏｎｄｕｃｔｉｎｇｍａｇｎｅｔｉｃｅｎｅｒｇｙｓｔｏｒａｇｅ(ＳＭＥＳ) ,ｓｕｐｅｒ ｃｏｎｄｕｃｔｉｎｇｍａｇｎｅｔｓ,ｓｕｐｅｒｃｏｎｄｕｃｔｉｎｇｆａｕｌｔｃｕｒｒｅｎｔｌｉｍ ｉｔｅｒｓａｎｄｃｕｒｒｅｎｔｌｅａｄｓ,ｅｔ… 相似文献
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MALIK Pravin KADOLI Ravikiran GANESAN N. 《浙江大学学报(A卷英文版)》2007,8(7):1044-1052
Numerical exercises are presented on the thermally induced motion of internally heated beams under various heat transfer and structural boundary conditions. The dynamic displacement and dynamic thermal moment of the beam are analyzed taking into consideration that the temperature gradient is independent as well as dependent on the beam displacement. The effect of length to thickness ratio of the beam on the thermally induced vibration is also investigated. The type of boundary conditions has its influence on the magnitude of dynamic displacement and dynamic thermal moment. A sustained thermally induced motion is observed with progress of time when the temperature gradient being evaluated is dependent on the forced convection generated due to beam motion. A finite element method (FEM) is used to solve the structural equation of motion as well as the heat transfer equation. 相似文献
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杨惠山 《泉州师范学院学报》2003,21(2):23-27
应用有限时间热力学理论，建立一类较普遍的不可逆斯特林热机模型，研究存在热阻、热漏、回热损失斯特林热机的优化性能，导出了热漏损失服从一般传热规律时热机的功率与效率间的优化关系，讨论了不同情况下热漏和回热损失对热机性能的影响，从而可为二热源热机的研制和优化设计提供新的理论指导。 相似文献
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针对三套加氢精制装置用能存在的不足,采取了装置间热联合、优化改进换热网络、充分利用低温热等措施。实现汽油加氢、航煤加氢两套装置的热量集成,汽油加氢的富余高温位热量正好用于航煤加氢装置高温位热量需求,柴油加氢装置低温热也得到了更有效的利用。三套装置经节能改进后,年节约能量488．893 MJ ,节能效果显著。 相似文献
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CHERALATHAN M VELRAJ R. RENGANARAYANAN S. 《浙江大学学报(A卷英文版)》2006,7(11):1886-1895
INTRODUCTION Cool thermal energy storage (CTES) using the latent heat concept as an alternative to sensible heat storage offers a good option because of its high storage density and the nearly constant temperature heat removal characteristics during the discharging cycle. Since the principle of latent cool storage nec- essarily involves a change of state, heat transfer must occur in different modes depending on the state of charging and discharging. During the periods of low cooling dema… 相似文献
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热交换系数源于牛顿冷却定律,是混凝土温度场控制技术理论和建筑热工物理学上的重要参数,对揭示温度场的内在本质关系和变化规律有重要的意义,本文研讨混凝土浇筑过程与外界空气直接接触产生热交换时的抉热系数的取值范围及风速对热交换系数所产生的影响,分析研究各种热交换系数和数学模型,指出理论上求解的困境,提出应加以注意的若干问题,根据传热学原理,利用传热系数的计算公式间接类比转化求得一个新的计算热交换系数的公式,探讨了相似理论和量纲分析原理及实验方法建立可求解热交换系数数学模型的可能性,为混凝土温度场效应分析正确选取热工参数的取值提供理论依据。 相似文献
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随着原油的含硫量增加,直馏航空煤油馏分中的硫醇硫随之增加,原有的精制工艺已出现或潜在许多问题,如硫醇硫含量超标、博士试验不合格等质量问题,需进一步发展完善以适应生产需要。直馏航煤精制脱硫醇的方法有加氢法．继化氧化法和吸附法等。文章在自主安装的试验装置,进行静态及动态吸附试验研究。通过静态吸附试验,在13种吸附剂中选定复合氧化锌作为吸附剂。在此基础上,考察了吸附剂结构形状对吸附精制效果的影响。试验结果表明,粉状吸附剂脱除硫醇硫质量百分率最高（98．1％）,粒状次之（34．9％）,条状最差（21．8％）;内扩散阻力是影响吸附过程的重要因素。 相似文献