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汽液固三相流化床沸腾传热的研究 总被引:15,自引:2,他引:13
对垂直管内汽液固三相流化床沸腾传热特性进行了实验研究和理论分析,建立了沸腾传热的计算方法.实验结果表明,由于固体粒子的存在,强化了沸腾传热.传热系数比汽液两相流提高2倍左右.沸腾过程的稳定性明显提高. 相似文献
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垂直管内三相流化床沸腾传热特性 总被引:14,自引:1,他引:14
研究了三相流化床沸腾传热的特性和影响传热系数的诸因素。在传热过程中,由于固体粒子的存在,强化了传热。以玻璃球粒子为固相的三相流化床沸腾传热系数,是相同条件下汽液两相流沸腾传热的二倍。以铜粒子为固相的三相流化床沸腾传热系数,是相同条件下汽液两相流沸腾传热系数的3倍。 相似文献
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引 言流动沸腾传热广泛存在于石油、化工、轻工、动力及能源等各个领域 ,但三相流动沸腾传热的研究极少 .李修伦等[1]在流动沸腾系统中加入惰性固体粒子 ,进行了汽 -液 -固三相流沸腾传热的初步研究 .李修伦、闻建平[2 ,3]进一步将三相流和沸腾换热相结合 ,较好地解决了沸腾传热强化和防垢、除垢问题 .李修伦、张利斌等[4 ]又采用循环流化床技术 ,结合粒子在沸腾系统中的强化特性 ,开发了汽 -液 -固三相循环流化床蒸发器 ,它具有良好的强化传热和防、除垢性能 .上述研究均属于单组分三相流动沸腾传热 ,而关于二元物系三相流动沸腾传热的研… 相似文献
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In order to solve the fouling problems in boiling processes,a boiling system was designedby adding solid particles to the boiling liquid In this paper.both theoretical analyses andexperimental studies on the boiling heat transfer in such a three-phase flow boiling were carried out.Based on the analysis of heat transfer characters of this three-phase flow boiling,a mathematical mod-el for the heat transfer coefficient of flow boiling was developed.The experiments show that,in thepresence of particles the boiling heat transfer is enhanced and is about 2 times that of the vaporliquid two phase one with better flow stability.The fluidized particles rub the heat transfer wall toprevent and to clean the fouling. 相似文献
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In order to enhance heat transfer and solve the fouling problems in boiling processes, a boiling system was designed by adding solid particles to the boiling liquid. In this paper, both theoretical analyses and experimental studies on the flow boiling heat transfer in a vapor-liquid-solid three-phase circulating fluidized bed evaporator were carried out. Based on the analysis of the heat transfer characters of this three-phase flow boiling, a mathematical model for predicting the flow boiling heat transfer coefficients of the vapor-liquid-solid three-phase circulating fluidized bed evaporator was developed. The experiments show that, in the presence of solid particles the flow boiling heat transfer is enhanced and is about 2 times that of the vapor-liquid two-phase one. The predicted results of the flow boiling heat transfer coefficients agreed well with the experimental data. 相似文献
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In flow boiling apparatus, fouling is frequently a problem. Mechanical methods to mitigate fouling include the impact of solids on the deposit to remove it. Solid particles fluidised by the two-phase boiling mixture may accomplish sufficient deposit removal to keep boiling surfaces clean. This results in a self-cleaning fluidised bed boiling heat exchanger. The particles additionally enhance the heat transfer. In this paper, a comprehensive investigation of three-phase fluidised flow boiling in a circulating system is presented. A test apparatus which is a three-phase circulating fluidised bed was built with glass construction to visualise boiling phenomena in a water system. It could also be operated as a two-phase system and this was investigated to provide the basis for comparison and also to verify reproducibility and confirm well-established flow boiling results. For the three-phase system (where steel particles were added), a range of liquid flowrates and heat fluxes was used and three different particle sizes were investigated. Three-phase results were compared with two-phase results. This work is primarily a study of boiling heat transfer enhancement as a result of addition of particles, but the effect of the particles creating a self-cleaning heat exchanger is a significant operational advantage for industrial application.As expected, heat transfer coefficients were higher overall for the three-phase system than for the two-phase system. The onset of nucleate boiling was independent of heat flux and the heat transfer coefficient initially increased with increasing Reynolds number whereafter there was some deterioration of heat transfer. Visualisation of boiling heat transfer phenomena for the three-phase system is also provided which allows mechanistic explanations of the measured phenomena.In Part II of this paper, a correlation is developed, based on boiling heat transfer modelling, to describe heat transfer during boiling in a three-phase circulating fluidised bed. A flow-dependent function is added as is a boiling heat transfer enhancement factor. This correlation is validated against this experimental data and found to show agreement within about 20% and better agreement with the data than an existing correlation. 相似文献