振动流化床中水平换热管与粗钛矿传热特性的研究

以粗粒级原钛矿为实验物料,测定了振动流化床与水平加热管间的传热系数,研究了粗钛矿在流化状态下的传热特性,并对影响传热过程的因素进行了分析,得出了适宜的操作条件。在操作气速0.1ms-1、振幅2mm及振动频率1100min-1的条件下,振动流化床水平换热管的传热系数达到最大值。实验结果为粗钛矿的高效节能干燥提供了重要实验依据。     

振动流化床与浸没水平管间局部传热系数的测试方法

本文提出了振动流化床中测试水平加热管局部传热系数的新方法。该法考虑了管体温度场的非均匀性对测量结果的影响。根据管体的材质和结构。扣除了由于分布引起热损失。从而采用较简单的测试手段就能够获得较准确的局部传热系数数据。将本所所得测试结果与其他研究者的测试结果作了比较。并上局部热系数求得的平均传热系数和实测的平均传热作了比较。结果表明,本文提出的测试方法可靠。     

浅层流化床水平埋管与床层间的传热

针对浅层气－固流化床床层与水平埋管间的传热特性进行了实验研究，同时利用光导纤维对床层与壁面间的接触动力学参数进行了检测，从而从流体力学的角度，分析了传热的实验结果。基于乳化团与气泡相与传热面的交替接触，通过理论分析，提出了浅层流化床中水平埋管传热的模型方程，模拟值能较好地与实验结果相符合。     

Heat Transfer to Immersed and Boundary Surfaces in Fluidized Beds

An experimental study of heat transfer into gas‐fluidized beds has been carried out with heat transfer into discriminated areas of the boundary walls, and into single and multiple elements immersed in the bed. The experiments have been carried out with glass ballotini ranging in size from 100 μm to 1 mm in diameter, on Diakon (Perspex) particles of 325 μm, and on nickel particles of 275 μm and 325 μm covering a range of Archimedes numbers from 100 to 10⁵. Beds of different diameter with distributors of several different types have been examined. The entire experimental results have been compared with literature data on heat transfer to immersed elements. It is shown that the onset of slugging in the fluidized bed has a large effect on heat transfer. Once the effect of slugging has been introduced, it is shown that the results of this investigation and others in the literature within the range of Archimedes numbers from 100 to 10⁹ may be correlated.     

循环流化床的沸腾传热

A model is proposed to predict boiling heat transfer coefficient in a three-phase circulating fluidized bed (CFB), which is a new type of evaporation boiling means for enhancing heat transfer and preventing fouling. To verify the model, experiments are conducted in a stainless steel column with 39 mm ID and 2.0 m height, in which the heat transfer coefficient is measured for different superficial velocities, steam pressures, particle concentrations and materials of particle. As the steam pressure and particle concentrations increase, the heat transfer coefficient in the bed increases. The heat transfer coefficient increases with the liquid velocity but it exhibits a local minimum.The heat transfer coefficient is correlated with cluster renewed model and two-mechanism method. The prediction of the model is in good agreement with experimental data.     

振动流化床中床层空隙率的分布

在φ１４８ｍｍ的振动圆柱形流化床内,采用树脂、玻璃珠、小米及砂子等Ｇｅｌｄａｒｔ‘Ｂ和Ｄ类物料,测定了振动强度为１－８ｇ,流化床为１．０－３．０条件下气固流化床床层空隙率的变化,考察振动条件下床层轴向径向的空隙率分布,探讨了床层空隙率的一些影响因素,并根据实验结果对振动流化床的平均空隙率进行了无因次数式关联,此关联式对实际振动流化床的操作与工程设计具有一定的指导意义。     

带浸没加热管的惰性粒子振动流化床干燥强度研究

采用带浸没加热管的惰性粒子振动流化床对（石灰）膏状物料干燥进行了实验研究。利用正交实验，考察了加料速率、振动条件、进气温度、进气速度、加热管功率等参数对干燥强度的影响，得出了计算干燥器干燥强度的关联式。结果表明，由于浸没加热管热量的引入，能显著增加干燥器的干燥能力，实验条件下干燥器干燥强度超过250kg·（m^3·h）^-1，干品湿含量可降至1．5％以下，质量能达到要求，相关数据可为膏状物料干燥器的设计和开发提供借鉴。     

振动流化床宽筛分玻璃粒子与水平管局部传热特性

以宽筛分玻璃粒子为实验物料,测定了振动流化床与浸没水平加热管间的局部传热系数,研究了通气速率、振动频率和粒度分布对局部传热系数的影响.结果表明,浸没水平管局部传热系数随流化气速和振动频率的增加先增大而后逐步减小;小颗粒的存在有利于增强加热管与床层的传热;大颗粒比例的增加不利于管壁与床层的传热.由实验数据整理了预测局部传热系数的经验公式,经验公式与实验数据误差在20%以内,吻合较好.     

Heat Transfer from Immersed Vertical Cylinders in Gas‐Liquid and Gas‐Liquid‐Solid Fluidized Beds

The heat transfer coefficient, h, was measured using a cylindrical heater vertically immersed in liquid‐solid and gas‐liquid‐solid fluidized beds. The gas used was air and the liquids used were water and 0.7 and 1.5 wt‐% carboxymethylcellulose (CMC) aqueous solutions. The fluidized particles were sieved glass beads with 0.25, 0.5, 1.1, 2.6, and 5.2 mm average diameters. We tried to obtain unified dimensionless correlations for the cylinder surface‐to‐liquid heat transfer coefficients in the liquid‐solid and gas‐liquid‐solid fluidized beds. In the first approach, the heat transfer coefficients were successfully correlated in a unified formula in terms of a modified j_H‐factor and the modified liquid Reynolds number considering the effect of spatial expansion for the fluidized bed within an error of 36.1 %. In the second approach, the heat transfer coefficients were also correlated in a unified formula in terms of the dimensionless quantities, Nu/Pr^1/3, and the specific power group including energy dissipation rate per unit mass of liquid, E^1/3D^4/3/ν_l, within a smaller error of 24.7 %. It is also confirmed that a good analogy exists between the surface‐to‐liquid heat transfer and mass transfer on the immersed cylinder in the liquid‐solid and gas‐liquid‐solid fluidization systems.     

Convective Heat and Mass Transfer Modeling in Gas‐Fluidized Beds

This review examines selected mechanistic and empirical models reported in the literature to predict convective heat and mass transfer coefficients in gas‐fluidized beds. The role of hydrodynamics in heat and mass transfer is briefly outlined before embarking on the modeling approaches. Both bed to wall and interphase heat transfer, are considered. In bed to wall heat transfer, the main focus of the review is the modeling of particle convective components, based on surface renewal. The concepts of transient and local heat transfer models are also discussed briefly. In the case of mass transfer, only interphase transfer is considered. Emphasis is placed on models based on combustion where mass transfer is seen to occur from a few active particles contained in a fluidized bed of inert particles.     

Computational Fluid Dynamics Study of Heat Transfer in Turbulent Fluidized Beds

The fluidization and heat transfer behaviors of a turbulent fluidized bed were investigated using computational fluid dynamics (CFD). The effects of inlet superficial velocity on heat transfer behaviors in a turbulent fluidized bed were analyzed and compared with those operated in other fluidization regimes. The effects of using particles belonging to different Geldart groups in a turbulent fluidized bed on fluidization and heat transfer behaviors were evaluated. For both fluidization regimes investigated, the solids temperature distribution during the heat transfer process became less uniform when the particle size was reduced.     

空气冷却器翅片管强化传热新途径

对空气冷却器翅片管强化传热新途径作了阐述,介绍了各种新型翅片管的结构形式、制造工艺和传热性能。同时,将具有代表性的新型翅片管的传热和摩擦阻力性能与传统的平直翅片管进行了比较,给出了相应的传热系数曲线、流动阻力系数曲线和实验公式。研究表明,空气冷却器翅片管经过强化传热改造后,传热效果显著提高。指出在制造和选择新型空气冷却器翅片管时,需要考虑综合因素。     

高温流化床乳化相与浸没表面间传热过程的数值模拟

应用建立的高温流化床乳化相与浸没表面间传热的表面-颗粒-乳化团理论模型,针对9种Geldart B类粒子高温流化床乳化相与浸没表面间的动态传热过程进行了数值模拟,发现在距浸没表面1个粒径范围内,乳化相的不均匀性和温度分布的不均匀性非常显著;随着乳化相在表面停留时间的延长,乳化相与浸没表面间的换热系数减小,在接触时间较短时换热系数下降较快. 对于所用Geldart B类粒子和950℃床温,传导换热系数占总换热系数的85%~45%,辐射换热系数占15%~45%,对流换热系数一般占10%左右;在粒径小于0.6 mm时,对流换热对总换热的贡献相对很小.     

不同内表面形式铜管传热和压损试验研究

搭建了铜管单管性能测试试验台,测试不同内表面形式铜管在水-水系统的换热和压损。测试表明,在水流速0.8~1.65 m/s范围内,内螺纹管的换热量较光管高7%~17%,总传热系数K较光管高9%~23%,管内换热系数α较光管高30%~60%,压损增加20%~30%;两种内螺纹管参数比较,齿顶角大、螺旋角大、齿数稍多的管型换热量大6%左右,总传热系数大7%~10%,管内换热系数α高20%~30%,压损大近10%。此项研究可以广泛应用于石油化工、环境调节等领域。     

空气冷却器及其强化传热翅片管型

对干式、湿式以及干湿联合式空气冷却器的换热特点、常用的翅片管结构、三维翅片等强化传热翅型以及空气冷却器翅片管的加工工艺、选材等方面进行了综述研究。采用套片式加工工艺的条缝型错置带状三维翅片和采用无屑加工方法成形的锯齿翅片,在较低空气流速下具有较高的传热因子和摩擦因子比,是提高空气冷却器空气侧换热的高效翅片管型,为石化行业空气冷却器翅片管的改造提供参考。     

Heat transfer between very shallow fluidized beds and an immersed horizontal tube

A new correlation is proposed for the heat transfer coefficient between an immersed horizontal tube and very shallow fluidized beds (static bed heights of 10-40 mm). The correlation is based upon experimental data obtained in this work for a horizontal tube with an outside diameter of 13.1 mm, immersed in beds of spherical alumina particles with mean particle sizes of 335-1261 microns. The maximum bed pressure drop was 92.5 mm water. The effects of tube elevation, static bed height and distributor design were investigated. Nine different distributors were used, with maximum pressure drops ranging from 3 to 800 mm water and open areas from 2.2 to 36%. A comparison between the proposed correlation and data reported in the literature showed an agreement of approximately ±10%.     

生物流化床的类型及特点

介绍了各种用于废水处理的生物流化床,对其结构组成、特点、适用范围及处理效果进行了分类阐述,重点总结了好氧流化床与厌氧流化床的发展概况,并指出了今后进一步研究与应用生物流化床的努力方向。     

换热器用多孔管沸腾传热物理模型比较

综述了针对多孔管沸腾传热的物理模型.分析了影响多孔表面沸腾传热的影响因素,对各种模型的优缺点进行了分析归纳,探讨了多孔管沸腾传热物理模型研究的发展方向,对今后的发展提出了自己的建议.     

异形管内水力、传热性能的数值模拟

通过数值计算考察了横纹管、缩放管两种异形管内的流动与传热性能。计算时采用标准k-ε湍流模型：采用控制容积法对控制方程进行离散化；采用SIMPLE算法进行压力修正：代数方程采用超松弛法迭代求解。很出了在充分发展流时的传热努塞尔数、速度、瘴撩系数及湍动能分布，并与光滑管内的流动传热进行了比较，分析了异形管在强化传热方面的机理。计算结果和实验值比较吻合。     

螺旋槽管内流体传热性能数值研究

研究了螺旋槽管内径Di、螺距P、槽深e等各因素对管内流体传热性能的影响,用数值模拟法进行传热系数数值计算,并与相同材质、相同直径和壁厚的光管同步对比。对计算结果进行线性回归处理,确立Nu与Re的关联式。结果表明,螺旋槽管具有较好的传热强化作用,在同等Re工况下,其传热系数较光管提高10%～60%。