共查询到17条相似文献，搜索用时 622 毫秒
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《实验室研究与探索》2016,(10):64-67
对铜光管和铜高通量管在不同的热流密度下的传热性能进行了实验研究,管内工质质量分数为70%的乙二醇水溶液,管外工质为饱和水蒸汽。结果表明,高通量管的强化传热性能非常明显,在实验范围内,高通量管的沸腾传热系数是光管的1.55~1.96倍,冷凝传热系数是光管的1.56~1.67倍,总传热系数是光管的1.54~1.87倍。对实验数据进行了分析,得到了高通量管在乙二醇水溶液和饱和水蒸汽中的传热关联式。根据此关联式,进行了高通量再沸器和普通再沸器的对比设计,高通量再沸器可节省换热面积33.5%。 相似文献
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程励辉 《福建工程学院学报》2023,(6):517-522
针对温度及风速对中空玻璃传热系数影响机制不明确的问题,采用因素分析法研究室外温度、风速对中空玻璃传热性能的影响,对比分析不同中空玻璃空腔内部换热方式及当量导热系数变化率;利用四分位数法探究了不同工程环境下,中空玻璃传热系数相对于产品设计基准值的偏离特征。结果表明：中空玻璃传热系数随室外风速升高而增大;普通中空玻璃空腔传热以辐射换热为主,而镀膜中空玻璃空腔传热以对流换热为主,且当空腔厚度在一定阈值内(普通中空玻璃约为20 mm,镀膜中空玻璃约为9 mm),空腔气体当量导热系数随室外温度升高而增大;中空玻璃传热系数出现负偏离较为显著。研究结果对优化工程项目的中空玻璃设计和产品选型具有指导意义。 相似文献
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介绍了一种用于强化管壳式换热器壳侧传热和支撑管束的螺旋折流片新型结构,该结构是对换热器管子相间地套上螺旋折流片以产生旋涡流动.研究模型是在正方形布置的4个管子中的2个对角管子套上螺旋折流片后形成的通道,利用FLUENT软件对该上述四管通道模型的流场和温度分布情况进行了数值模拟;分析了四管通道模型中螺旋折流片对强化传热和流动阻力随雷诺数的变化关系的影响.算例结果显示该新型结构可比相同尺寸的光管通道中的情形传热系数提高约40%～55%,同时也将伴随较高的流动阻力.可以相信螺旋折流片式换热器将会在许多工业领域有良好的应用前景. 相似文献
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自主研制了一种稠油高压吞吐室内模拟实验装置,并将其应用于实验教学。该装置采用流体暂存储能器和加热恒温层及保温管线,解决了稠油吞吐模拟实验中填砂模型的"吞"与"吐"的能力和热量保持问题。利用该装置开展了稠油冷采、加热激励和蒸汽吞吐实验。结果表明,温度和压力对稠油的采油指数影响明显,56℃时,为28.0 mL/(min·MPa)(10 MPa)和26.9 mL/(min·MPa)(6 MPa);80℃,平均采油指数增至80.4 mL/(min·MPa)(10 MPa)和56.0 mL/(min·MPa)(6 MPa)。蒸汽吞吐激励后稠油的采油指数较冷采有明显提高,且随着蒸汽温度提高而增大。蒸汽温度从120℃提高至240℃时,平均采油指数增加了0.85倍。注蒸汽吞吐激励后采油指数可达冷采的1.3～2.5倍。 相似文献
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北春 《中学课程辅导(初二版)》2007,(12):41
1．用砂锅煮肉或烧汤时，当汤水沸腾后从炉子上拿下来，则汤水仍会继续沸腾一段时间，而铁、铝锅却没这种现象，这是为什么？
因为砂锅是陶土烧制成的，而非金属的比热比金属大得多，传热能力比金属差得多。当砂锅在炉子上加热时，锅外层的温度大大超过100℃，内层温度略高于100℃。此时，锅吸收了很多热量，储存了很多热能。 相似文献
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基于FLUENT软件对制冷剂R134a在水平螺旋槽管管外沸腾换热进行了三维数值模拟,得到了其饱和泡状沸腾过程中体积含汽率的分布规律和换热系数,并和光管进行了比较。结果表明螺旋槽管外侧能够很好地强化沸腾传热。此外,还通过改变边界条件分析了质量流量、热流密度的变化对螺旋管管外沸腾换热系数的影响。 相似文献
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蒙永寅 《南宁师范高等专科学校学报》2010,(5):29-31
采用试差法,参考换热器传热系数的大致范围,假设一个传热系数值,利用热量衡算和传热速率方程估算传热面积,初选换热器型号,最后校核传热系数和传热面积。 相似文献
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This study addresses heat transfer performance of various configurations of coiled non-circular tubes, e.g., in-plane spiral ducts, helical spiral ducts, and conical spiral ducts. The laminar flow of a Newtonian fluid in helical coils made of square cross section tubes is simulated using the computational fluid dynamic approach. The effects of tube Reynolds number, fluid Prandtl number, coil diameter, etc., are quantified and discussed. Both constant wall temperature and constant heat flux conditions are simulated. The effect of in-plane coil versus a cylindrical design of constant coil, as well as a conical coil design is discussed. Results are compared with those for a straight square tube of the same length as that used to form the coils. Advantages and limitations of using coiled tubes are discussed in light of the numerical results. 相似文献
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HUANG Wei-jun DENG Xian-he ZHOU Shui-hong 《重庆大学学报(英文版)》2006,5(1):8-12
1 Introduction A well known method to increase heat transfer from a surface is to roughen the surface by use of regular geometric roughness elements, such as transversely-ridged tube, spirally-ridged tube or converging-diverging tube, etc., on the surface… 相似文献
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对弹性管束水-水换热器的传热与阻力特性进行了研究。主要分析了换热器在不同工况下的传热系数的变化规律;研究了弹性管束在管外流体和管内流体的共同诱导作用下,管外和管内对流换热的情况;并对管程和壳程的流动阻力损失进行了实验测量,得出了管程和壳程的阻力损失变化的规律,以及换热器管程阻力损失的计算方法。 相似文献
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以水一水换热为实验对象,研究了螺旋隔板单管换热器的传热与流阻性能。实验结果表明,在相同的Re值下,螺旋隔板花瓣管单管换热器的壳程传热准数Nu是螺旋隔板光滑管单管换热器的2—4倍,压降只是它的1．4—1．8倍,证明花瓣管具有十分优越的强化传热性能,其与螺旋隔板搭配构成的换热器具有良好的传热与压降性能。在实验范围内,花瓣管翅片高度的增加、翅间距的减少都有利于传热强化性能的提高。 相似文献
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1 Introduction The traditional segmental baffle heat exchangers(SHE) can be si mply manufactured and run reliably,but they are mainly suitable for the situation of lowerflow velocity. When fluid velocity becomes higher inthe shell side ,the pressure dropi… 相似文献
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With isopentane as working fluid, the heat transfer performances for corrugated, nodal and horizontal grain tubes are simulated. The structural parameters of the three kinds of tubes are compared with those of the plain tube. The numerical results using computational fluid dynamics are validated with theoretical values. For the corrugated, nodal and horizontal grain tubes, the heat transfer enhancements(HTEs) are 2.31—2.53, 1.18—1.86 and 1.02—1.31 times of those of the plain tube, respectively. However, the improved HTEs are at the expense of pressure losses. The drag coefficients are 6.10—7.09, 2.06—11.03 and 0.53—1.83 higher, respectively. From the viewpoint of comprehensive heat transfer factor, the corrugated tube is recommended for engineering applications, followed by the horizontal grain tube. 相似文献
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Coaxial liquid-liquid flows were numerically studied in a nesting two-tube system. Calculations were carried out when various exit-lengths （meaning length differences between the two tubes） were used. Numerical results indicated that there exists a certain range of exit-length for the liquid-liquid flows to form stable and smooth interfaces, which requires that the exit-length should roughly be less than 5.6 times the outer tube diameter. In this range, interface instability is effectively restrained and the core fluid shows a phenomenon of die swell. When the exit-length is about 1.6 times the outer tube diameter, the core fluid has the greatest diameter size in the shell fluid. Velocity distributions at the outer tube exit favor formation of a continuous and stable core-shell structure. 相似文献