共查询到20条相似文献,搜索用时 95 毫秒
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为提高降膜流动过程中的传热效率,搭建水平降膜传热性能测试装置,以水为系统循环工质,实验研究热流密度(0—5 582 W/m~2)、喷淋密度[0.14—4.16 kg/(m·s)]和喷淋温度(20—40℃)对单根半椭圆管水平降膜管外传热系数分布和变化规律,并与相同管截面外周长圆管、椭圆管对比。结果表明:随着热流密度、喷淋密度和喷淋温度的增加,半椭圆管水平降膜管外平均传热系数不断增大,喷淋密度较小时,传热系数增加速率更大;沿管管截面圆周向角方向,半椭圆管、椭圆管和圆管的水平管外降膜传热系数变化趋势基本一致,先明显减小,最后略微增大;半椭圆管比圆管、椭圆管的水平降膜管外平均传热系数更高,具有重要的工程应用价值。 相似文献
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表面多孔管降膜沸腾传热研究 总被引:2,自引:1,他引:2
测试了第一二代机械加工表面多孔管的单管降膜沸腾传热性能。对JK-1管和JK-2管的降膜沸腾强化传热机理作了定性分析,并根据实验数据建立了简单的经验关联式。 相似文献
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油气集输换热设备中,更多关注的是强化对流传热的研究和应用,而对于管外强化沸腾换热关注较少。在介绍池沸腾传热相关理论一般性原理的基础上,分析了影响池沸腾传热的主要因素。通过改良换热管外表面结构型式,在换热管表面形成凹凸或多孔的结构,这种结构下沸腾传热提高了一个数量级。选择合适的外界压力能够强化管外沸腾传热,提高了管外换热系数。最后讨论了池沸腾传热计算的有关问题。 相似文献
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本文研究了含有高浓度惰性组分的苯酐蒸汽立式强迫对流膜状冷凝过程,提出了该过程的物理模型和计算传热系数的数学模型。该模型的计算结果与实验结果吻合良好。研究表明:传热过程的主要阻力集中在静止的气膜层中。 相似文献
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在聚氯乙烯干燥过程中,目前通常采用的是气流-旋风两段式干燥,通过对固体干燥原理、干燥过程的分析,将干燥过程分为表面汽化干燥与升温干燥2个阶段,根据气流干燥器的特点,结合各个阶段传质、传热的特点,分段建立了传质速率、传热速率方程,物料衡算、热量衡算方程。通过对气流干燥器的分析研究,确定了计算机模拟过程中的各个参数,从而确立了气流干燥器的数学模型。 相似文献
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Vimal Kumar 《Chemical engineering science》2007,62(9):2386-2396
In the present work attempts are made to investigate the hydrodynamics and heat-transfer characteristics of a coiled flow inverter (CFI) as heat exchanger at the pilot plant scale. The experiments are carried out in counter-current mode operation with hot fluid in the tube side and cold fluid in the shell side. Experimental study is made over a range of Reynolds numbers from 1000 to 16,000 using water in the tube side of the heat exchanger. The shell side fluids used are either cooling water or ambient air. The coiled flow inverter is made up of coils and 90° bends and inserted in a closed shell. The shell side is fitted with three types of baffles to provide high turbulence and avoid channeling in the shell side. The bulk mean temperatures at various downstream positions are reported for different flow rate on tube side, as well as the heat transfer efficiency of the heat exchanger is also reported. Pressure drop and overall heat-transfer coefficient is calculated at various tube and shell side process conditions. The outer and inner heat-transfer coefficients are determined using Wilson plot technique. The results show that at low Reynolds numbers, heat-transfer is 25% higher as compared to coiled tubes. At high Reynolds numbers, the configuration has less influence on heat transfer. New empirical correlations are developed for hydrodynamic and heat-transfer predictions in the coiled flow inverter. 相似文献
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The concept of a pseudoequilibrium process is proposed to describe heat transfer in boiling solutions of liquids. The bubble-formation and bubble-relaxation stages are considered. Either stage is characterized by its own driving force of heat transfer. The concept of the average temperature of a bubble ensemble is introduced to calculate the heat-transfer coefficient at either stage, and a solution is obtained for complete ensembles. A new method for calculating the heat-transfer coefficient is developed. The calculated data are compared with experimental data for 12 systems, including one ternary system. 相似文献
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天然气加热炉是采用中间载热介质间接加热的一种特殊的炉型形式,中间载热介质的性质及其传热过程的形成是影响天然气加热炉效率的重要关键因素。本文通过天然气加热炉试验系统对大筒体内水和乙二醇两种不同中间载热介质的温度分布和热流场进行了分析比较,研究不同中间载热介质对天然气加热炉换热的影响,并结合工程实际的需要,从中间载热介质的选择和加热炉整体传热结构两方面,提出了改善天然气加热炉效率的有效途径,并获得了国家发明专利授权。 相似文献
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V. V. Potapov A. A. CerdanJr. V. A. Gorbach E. A. Litmanovich G. V. Terpugov V. N. Mynin 《Theoretical Foundations of Chemical Engineering》2007,41(5):599-605
A process flowsheet with baromembrane facilities to recover colloidal silica from a hydrothermal heat-transfer medium is proposed. The flowsheet is developed with taking into account data on the kinetics of nucleation and polymerization of orthosilicic acid, the size distribution of colloidal particles, and experiments on the recovery of particles using membrane filters of various pore diameters. The use of membrane filters allows one to obtain amorphous silica with a reduced impurity content and a high specific surface area, as well as an aqueous hydrosol of colloidal silica. 相似文献
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A mathematical model of removal of large amounts of an organic liquid from a capillary-porous body in a superheated steam current is elaborated. The model can be used to determine the heat-transfer coefficients and the drying rate for all periods of the process and estimating the change in the composition of the liquid phase passing into the pores of the material in the first three periods for different process parameters.Translated from Khimicheskie Volokna, No. 6, pp. 49–52, November–December, 2004. 相似文献