共查询到19条相似文献,搜索用时 515 毫秒
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本介绍了一种新型省煤器,即钎焊渗层螺旋翅片管省煤器。这种新型省煤器具有较高的传热效率,可有效地解决磨损问题,提高锅炉平均工作时间,是传统省煤器的理想换代产品。 相似文献
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栾红霞 《能源技术(上海)》2002,23(5):208-209
介绍了一种新型省煤器 ,即钎焊渗层螺旋翅片管省煤器。这种新型省煤器具有较高的传热效率 ,可有效地解决磨损问题 ,提高锅炉使用率 ,是传统省煤器的理想换代产品 相似文献
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高压给水加热器采用小螺旋角的内外螺旋三角翅片管强化传热的试验研究 总被引:5,自引:0,他引:5
通过确切了解电站高压加热器的传热性能和特殊的设备要求,设计并加工出小螺旋角的内外螺旋三角翅片管用于强化其传热性能。基础实验表明,在实验的条件下,立式小螺旋角的内外螺旋三角翅片管的总传热系数比光滑管提高63%-95%,其中管外冷凝换热系数是同条件下光滑管的3.5-4倍,管内的对流换热系数也比光滑管提高了18%。同螺旋槽等比较可知,立式小螺旋角的内餐螺旋三角翅片管的总换热系数比螺旋槽提高4%-27%, 相似文献
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采用数值模拟技术对错列布置光管及螺旋翅片管、顺列螺旋翅片管的双相流场进行了数值模拟,分析了不同结构、不同排列方式的省煤器的抗磨性能.分析了翅片结构对颗粒运动与流场的影响,指出翅片的存在使烟气中的大颗粒飞灰较难碰撞到基管的表面,增强了省煤器的抗磨损能力. 相似文献
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介绍了烟气换热领域常用的两类高频焊钢质螺旋翅片管.指出目前存在多种连续型与锯齿型高频焊螺旋翅片管翅片效率计算方法,不便于同类换热实验结果的相互比较.通过深入分析与计算比较,对连续型与锯齿型高频焊螺旋翅片管分别给出了建议的翅片效率计算方法,供相关的工程设计及实验研究选用.两种管型的翅片效率比较表明,锯齿翅片的翅片效率较高,提高的幅度随翅片高度增大而增大. 相似文献
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Experiments were performed to compare the shell-side heat transfer coefficient and pressure drop of a helically baffled heat exchanger with petal-shaped finned tubes to those of low-finned tubes for oil cooling using water as a coolant. The experimental results showed that for the heat exchanger with petal-shaped finned tubes, the shell-side heat transfer coefficients were augmented by 28–48%, yet the shell-side pressure drops were reduced by 35–75% at the same volumetric flow rates of oil. The possible mechanisms responsible for this heat transfer enhancement were analyzed for helically baffled heat exchanger combined with petal-shaped finned tubes. 相似文献
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采用数值模拟方法,对径向错列翅片管内含不凝结气体水蒸气的凝结对流换热及阻力特性进行了综合分析。将编写的自定义函数(UDF)导入ANSYS FLUENT软件,对新型强化管传热性能和阻力性能进行了数值模拟,并根据管长方向壁面上蒸汽质量分数的变化情况,讨论分析了凝结过程中翅片管传热性能的变化规律。分析结果表明:与光管相比,内翅片管的强化传热效果随翅数增多、翅片换热接触面积增大而更加显著;另一方面,翅片管的流动阻力相应增大,对管路换热产生不良影响。在所研究翅型范围内16翅y=2x~2型翅片管综合强化换热效果更优;此外随着换热过程的持续,蒸汽凝结逐渐放缓;入口速度增大导致水蒸气凝结不充分,对换热效果的提升有一定制约。 相似文献
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Özden A?ra Hakan Demir ?. Özgür Atay?lmaz Fatih Kanta? Ahmet Selim Dalk?l?ç 《International Communications in Heat and Mass Transfer》2011,38(10):1384-1391
This study investigates passive heat transfer enhancement techniques to determine the distribution of temperature and static pressure in test tubes, the friction factor, the heat flux, the temperature difference between the inlet and outlet fluid temperatures, the pressure drop penalty and the numerical convective heat transfer coefficient, and then compares the results to the experimental data of Zdaniuk et al. It predicts the single-phase friction factors for the smooth and enhanced tubes by means of the empirical correlations of Blasius and Zdaniuk et al. This study performed calculations on a smooth tube and two helically finned tubes with different geometric parameters also used in the analyses of Zdaniuk et al. It also performed calculations on two corrugated tubes in the simulation study. In Zdaniuk et al.'s experimental setup, the horizontal test section was a 2.74 m long countercurrent flow double tube heat exchanger with the fluid of water flowing in the inner copper tube (15.57–15.64 mm i.d.) and cooling water flowing in the annulus (31.75 mm i.d.). Their test runs were performed at a temperature around 20 °C for cold water flowing in the annulus while Reynolds numbers ranged from 12,000 to 57,000 for the water flowing in the inner tube. A single-phase numerical model having three-dimensional equations is employed with either constant or temperature dependent properties to study the hydrodynamics and thermal behaviors of the flow. The temperature contours are presented for inlet, outlet and fully developed regions of the tube. The variations of the fluid temperature and static pressure along tube length are shown in the paper. The results obtained from a numerical analysis for the helically tubes were validated by various friction factor correlations, such as those found by Blasius and Zdaniuk et al. Then, numerical results were obtained for the two corrugated tubes as a simulation study. The present study found that the average deviation is less than 5% for the friction factors obtained by the Fluent CFD program while Blasius's correlation has the average deviation of less than 10%. The corrugated tubes have a higher heat transfer coefficient than smooth tubes but a lower coefficient than helically finned tubes. The paper also investigates the pressure drop penalty for the heat transfer enhancement. 相似文献
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对椭圆钎焊翅片管和双金属轧制翅片管换热器的传热及阻力性能进行试验对比研究,试验得到了一系列工况下的传热数据与管外空气流动阻力数据,给出了相应的传热系数、流动阻力曲线。从总传热系数中分离出管外空气侧的对流换热系数,得到了具有一定应用价值的管外换热的计算关联式;拟合得到了管外阻力计算关联式。结果表明:椭圆钎焊翅片管比双金属轧制翅片管的传热系数约高9%,管外换热系数约高17%,且管外空气流动阻力约低11%。 相似文献
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Longjian Li Quan Liao Tien-Chien Jen Qinghua Chen 《International Journal of Heat and Mass Transfer》2005,48(10):1916-1925
Experiments are performed to investigate the single-phase flow and flow-boiling heat transfer augmentation in 3D internally finned and micro-finned helical tubes. The tests for single-phase flow heat transfer augmentation are carried out in helical tubes with a curvature of 0.0663 and a length of 1.15 m, and the examined range of the Reynolds number varies from 1000 to 8500. Within the applied range of Reynolds number, compared with the smooth helical tube, the average heat transfer augmentation ratio for the two finned tubes is 71% and 103%, but associated with a flow resistance increase of 90% and 140%, respectively. A higher fin height gives a higher heat transfer rate and a larger friction flow resistance. The tests for flow-boiling heat transfer are carried out in 3D internally micro-finned helical tube with a curvature of 0.0605 and a length of 0.668 m. Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D internally micro-finned helical tube is increased by 40-120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance is increased by 18-119%, respectively. 相似文献