EFFECT OF IMPELLER AND VESSEL SIZE ON IMPELLER POWER NUMBER IN CLOSED VESSELS FOR REYNOLDS NUMBERS BETWEEN 40 AND 65000

Impeller power numbers in closed square vessels with/or without baffles and in closed cylindrical vessels with baffles were studied for impeller Reynolds numbers in the range between 40 and 65000. Flat vertical blade disk style, vertical blade open style and 45° pitched blade open style impellers were used. It was found that the impeller power number is affected by the vessel and impeller size and the system scale up     

MULTI-PASS SOLAR HEATER WITH HEAT-EXCHANGING PASSES AND EXPOSED TO NON-UNIFORM RADIATION

This is an analytical treatment of the multi-pass solar fluid-heater when the received radiant energy is non-uniformly distributed in the cross direction, normal to the flow. Adjacent passes are allowed to exchange energy. Closed-form formulas are derived for the fluid and wall temperature distributions along different passes. Mathematical expressions are presented for two performance indices, the efficiency and the effectiveness.     

MIXING IN CLOSED VESSELS - SUSPENSION OF SOLID PARTICLES AND POWER DEMAND

The suspension of solid material in a closed vessel has been studied. The vessel was designed as a pressure vessel having dished ends. Both the impeller speed at the off-bottom suspension point as well as the power demand related to this speed have been determined. In the study, emphasis was placed on studying the influence of both form and position of the baffles

It was found that a new dimensionless number, designed to describe the phenomena related to the suspension of particles, is a function of the impeller Reynolds number at the off-bottom suspension point. The impeller Reynolds number was varied between 10000 and 800000

Based on the results of this study, it can be stated that the design and position of the baffles are of great importance in minimizing the power demand in the suspension of particles. At the off-bottom suspension point, the power demand was lower for solid baffles when compared with baffles constructed of rods.     

通气式搅拌釜功率消耗的探讨

评估了通气式搅拌釜较有代表性的搅拌功耗关联式，指出大气穴形成之前，气体再循环将导致关系联式预测值偏离实际值４０％以上。用气体再循环系数对关联式进行修正，可得到适用于装有涡轮搅拌器的低粘体系的新的搅拌功耗关联式：当Ｇ≤２．５４时，Ｐｇ／Ｐ０＝０．７１Ｇ－０．８０；当Ｇ〉２．５４时，Ｐｇ／Ｐ０＝１．０；式中，Ｇ＝（Ｎｐ０／Ｎｐ０＾＊）＾０．６（ｄ／Ｄ）＾０．１５Ｆｒ＾０．０５［（１＋α）Ｎｑ］＾－０．     

非标准釜中双层桨的搅拌功率和气含率

在装有单层或双层蛇管换热器的搅拌釜中，分别以六直叶圆盘涡轮（ＤＴ）、四叶（４５°）折叶桨（４ＩＢＴ）或六叶（４５°）折叶桨（６ＩＢＴ）为上层桨，ＤＴ为下层桨，测定了不同双层桨的搅拌功率和气含率。结果表明，搅拌功率随蛇管层数、液位高度和桨间距的增加而增大，但气含率随液位的上升而下降。在装有双层蛇管换热器的搅拌釜中，ＤＴ与６ＩＢＴ双层桨的通气搅拌功率Ｐａ和气含率α的关联式为Ｐａ＝２．４９（Ｐ０２ＮＤ３／ＱＧ（０．５６））（０．３７）及α＝０．０２９Ｐ＿ｖ￣（０．４８）ｕ＿ｓ￣（０．４７）。     

不同类型搅拌器的气—液分散和混合特性

在通气式搅拌槽内研制了直叶圆盘涡轮、直叶桨式涡轮、４５度折叶圆盘涡轮、４５度折叶桨工涡轮、凹弧叶圆盘涡轮、锥形涡轮和布鲁马金式搅拌器的临界分散转速、分散状态、搅拌功率、气含率、气泡停留时间、排量准数和输出效率，并获得了适用上述种类搅拌器的临界分散转速、搅拌功率、气含率和气泡停留时间关联式。     

翼型组合桨持气特性的实验研究及数据关联方法

研究了内径φ0.382～1.16m机械搅拌釜中翼型组合桨气液两相的持气特性,考察了结构参数 (包括翼型桨径、桨间距、桨下距离、通气位置、挡板形式及翼型桨排出流方向)和操作参数 (包括搅拌转速与通气量)对气含率的影响.采用单位体积功率和表观气速及Froude数和通气流动数两种方法对气含率进行了关联处理,并采用神经网络技术建立了翼型组合桨的气含率关联的网络模型,该模型掌握了各参数对气含率的影响规律,具有很好的泛化能力,与传统关联方法相比,网络模型的预测误差可缩小至±10％以内.     

HOLDUP, INTERFACIAL AREA AND POWER REQUIREMENTS IN TURBINE AGITATED GAS-LIQUID CONTACTORS

This paper reports a detailed study of the hydrodynamic variables involved in the operation of 6-blade (flat) turbine agitated gas-liquid contractors. New information is presented regarding the characteristic velocity of the dispersed gas bubbles. Generalized correlations for prediction of power consumption of impellers under aeration conditions, gas phase holdup, characteristic velocity, mean residence time of gas bubbles, interfacial area of contact and mean bubble size are proposed in terms of system variables.     

HOLDUP,INTERFACIAL AREA AND POWER REQUIREMENTS IN TURBINE AGITATED GAS-LIQUID CONTACTORS

This paper reports a detailed study of the hydrodynamic variables involved in the operation of 6-blade (flat) turbine agitated gas-liquid contractors. New information is presented regarding the characteristic velocity of the dispersed gas bubbles. Generalized correlations for prediction of power consumption of impellers under aeration conditions, gas phase holdup, characteristic velocity, mean residence time of gas bubbles, interfacial area of contact and mean bubble size are proposed in terms of system variables.