Heat and Mass Transfer Enforcement of Vibrating Fluidized Bed

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Numerical Study of Heat Transfer Enhancement by Liquid Film on the Walls

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Hydrodynamic and Heat Transfer Characteristics of Magnetofluidized Beds

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Convective Heat and Mass Transfer in Water at Super—Critical Pressures under Heating or Cooling Conditions in Vertical Tubes

ＣｏｎｖｅｃｔｉｖｅＨｅａｔａｎｄＭａｓｓＴｒａｎｓｆｅｒｉｎＷａｔｅｒａｔＳｕｐｅｒ－ＣｒｉｔｉｃａｌＰｒｅｓｓｕｒｅｓｕｎｄｅｒＨｅａｔｉｎｇｏｒＣｏｏｌｉｎｇＣｏｎｄｉｔｉｏｎｓｉｎＶｅｒｔｉｃａｌＴｕｂｅｓ￥Ｐｅｉ－ＸｕｅＪｉａｎｇ；Ｚｅ－Ｐ...     

An Experimental and Numerical Study of Natural Convection Heat Transfer in Horizontal Annuli between Eccentric Cylinders

ＡｎＥｘｐｅｒｉｍｅｎｔａｌａｎｄＮｕｍｅｒｉｃａｌＳｔｕｄｙｏｆＮａｔｕｒａｌＣｏｎｖｅｃｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎＨｏｒｉｚｏｎｔａｌＡｎｎｕｌｉｂｅｔｗｅｅｎＥｃｃｅｎｔｒｉｃＣｙｌｉｎｄｅｒｓ￥ＷａｎｇＳｕｏｆａｎｇ（Ｄｅｐａｒｔｍ...     

An Investigation of the Swirling Flow and Heat Transfer in a Duct

This paper presents the results of experiments and numerical simulation of the turbulent swirling flow and heattransfer in a duct.The calculated results are in good agreement with data obtained by measurements.It isfound that the swirling flow promotes heat transfer to the wall of the duct;the swirl numbers are dependentupon the vane exit angles of the swirler,distance from the swirler and the duct Reynolds number.But the decayof swirling flow in streamwise direction is related to local Reynolds numbers and is independent of the swirlerexit angle.The swirl flow characteristics presented in this paper may be used for engineering purposes.     

Natural Convective Heat and Mass Transfer of Water with Corrosion Products at Super—Critical Pressures under Cooling COnditions

A numerical study is reported of laminar natural convective heat and mass transfer on a vertical cooled plate for water containing metal corrosion products at super-critical pressures. The influence of variable properties at super-critical pressures on natural convection has been analyzed. The difference between heat and mass transfer under cooling or heating conditions is also discussed and some correlations for heat and mass transfer under cooling conditions are recommended.     

Analytical Solution of Coupled Laminar Heat-Mass Transfer in a Tube with Uniform Heat Flux

Analytical solution is obtained of coupled laminar heat-mass transfer in a tube with uniform heat flux. This corresponds to the case when a layer of sublimable material is coated on the inner surface of a tube with its outer surface heated by uniform heat flux and this coated material will sublime as gas flows throught the tube.     

Experimental Investigation of Local Heat Transfer and Skin Friction in Tube Coils

Local heat transfer and skin friction around the tube perimeter of coils were studied in airflow. The heat transfer experiments were performed with two different coils D/d = 23 and 15.6, and skin friction experiments were performed with three different coils D/d = 25, 13.3 and 6.67 In the wide range of Re number from 4×103 till 105 . Variation of the local heat transfer around the perimeter and along the tube was defined. The behavior of the shear stresses at the wall and of the flow modes were studied. Investigations of the heat transfer indicated that with the increase of D/d the difference between heat transfer in the initial thermal section and the stabilized heat transfer increases. Investigations of the shear stress and its fluctuations indicated that, in large-curvature coils, the transition from laminar-vortex flow to turbulent flow around the tube perimeter takes place at different values of Re. In the region of the external generatrix of the bend, the transition occurs at smaller Re, whereas a     

Natural Convective Heat and Mass Transfer on a Vertical Heated Plate for Water Flow Containing Metal Corrosion Particles

Corrosion products of structural materials when contained in water usually are in two states:soluble state andcolloidal particles with diameter about 10~(-3)—10~(-1)μm.Deposits of such corrosion products on tube surfacesunder high pressure will jeopardize the operating economy of power plant equipment and even result in accidents.A numerical study is reported in this paper of the natural convective heat and mass transfer on a vertical heatedplate subject to the first or mixed kind of boundary conditions for high-pressure water(P=17MPa)containingmetal corrosion products with consideration of variable thermophysical properties.     

Experimental investigation of heat transfer enhancement using impingement of multiple water jets

The problem of cooling electronic components has become a subject of special interest in recent years due to the increasing capacity and rapidly decreasing size of electronic components. Direct contact cooling using multiple jet impingement is considered the most effective method. The heat transfer problem is complex and a better understanding of the jet impingement method is essential for the proper application of this method for electronic cooling. Investigations were carried out using an electrically heated test plate. Heat flux in the range of 25 to $200 \ \hbox{W/cm}^{2}$ , which is a typical requirement for cooling high power electronic components was dissipated using 0.5‐mm diameter water jets arranged in a 7×7 array with a pitch of 3 mm. Temperature difference between the test plate and water was within $30 \ ^{\circ}\hbox{C}$ . Tests were performed in the flow rate range of 22 to 40 ml/min, resulting in a Reynolds number range of 1100 to 1750. Results show a significant increase in the heat transfer coefficient or Nusselt number with an increase in heat flux. The effect of the flow rate or Reynolds number on the heat transfer coefficient is found to be negligible. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20291     

在第二类吸收式热泵中对螺旋槽管的换热性能研究

为了提高在以溴化锂为工质的第二类吸收式热泵吸收器的性能,在第二类吸收式热泵吸收器内对不锈钢螺旋槽管,即不锈钢光滑管的传热传质性能进行了实验研究.发现螺旋槽管的传热传质性能约为光滑管3倍,螺旋槽管内热媒工质-水的流体阻力系数是光滑管的17～20倍;应用于第二类吸收式热泵中间大大降低换热面积,促进热泵的高效紧凑化.     

利用流体脉动强化换热的试验研究

通过管内流体脉动的试验研究,分析脉动流体的水力参数和脉动特性对强化换热的影响规律。采用自行研制的自激振荡腔作为流体产生脉动的装置,并通过改变自激振荡腔的腔室长度和后喷嘴长度来达到调节流体脉动特性参数的目的。结果表明：流体的水力参数和自激振荡腔结构对流体脉动强化换热都有显的影响,随着流量或自激振荡腔腔室长度的增加,换热效果将增强;而后喷嘴长度则存在一个最优尺寸,在此处,换热效果最好。     

Experimental and Numerical Simulations of Flow and Heat Transfer in Heat Exchanger Elements Using Liquid Crystal Thermography

Experimental and numerical investigation of heat transfer and fluid flow were conducted for classic heat exchanger elements (flat plate with fin-tubes in-line, staggered and with vortex generators) and corrugated-undulated ducts under transitional and weakly turbulent conditions.The dependence of average heat transfer and pressure drop on Reynolds number and geometrical parameters was investigated. Distributions of local heat transfer coefficient were obtained by using liquid crystal thermography and surface-averaged values were computed. Three-dimensional numerical simulations were conducted by a finite-volume method using a low-Reynolds number k-e model under the assumption of fully developed flow. Computed flow fields provided otherwise inaccessible information on the flow patterns and the mechanisms of heat transfer enhancement.     

Evaluating the performance of forced convection heat transfer enhancement

Two methods for assessing thermal performance were evaluated for four kinds of forced convective heat transfer augmentations. On method uses the first law of thermodynamics, i.e., the heat transfer improvement at (1) constant Reynolds number, (2) constant pressure loss, and (3) constant pumping power. The other method uses the second law of thermodynamics, i.e., the entropy generation. The first method restricts the effective region and the second method supplies the condition for achieving the minimum entropy generation rate. © 1998 Scripta Technica, Heat Trans Jpn Res, 27(2): 142–154, 1998     

An experimental investigation of heat transfer in pin fin array

Detailed heat transfer measurements were performed by using 178 thermocouples in a channel with pin fin array. Local heat transfer coefficients and local heat transfer enhancement coefficients were obtained for eight Reynolds numbers ranging from 2000 to 100,000 on the endwall of the channel. The endwall boundary conditions for heat transfer investigation are heating the bottom endwall and heating symmetrically the bottom and top endwalls with constant heat flux. The mechanism of heat transfer enhancement with pin fin array has been discussed. © 2001 Scripta Technica, Heat Trans Asian Res, 30(7): 533–541, 2001     

纵向涡强化竖直平板自然对流换热的实验研究

对纵向涡强化竖直平板自然对流换热进行了实验研究。结果表明，在一定的Rayleigh数范围内，直角三角翼纵向涡发生器的攻角、翼高、翼宽等几何参数是影响强化换热的主要因素。存在最佳攻角；宽高比一定时，翼高和翼宽的变化会影响换热的效果。发现在直角三角翼阵列中前排直角三角翼产生的纵向涡可以强化后排直角三角翼纵向涡的换热。将直角三角翼与矩形低肋换热表面的性能作了对比性实验，在其他条件相同的情况下，直角三角翼强化换热的效果优于矩形低肋。     

Mass and heat transfer enhancement of chemical heat pumps

An inert additive, expanded graphite (EG), has been prepared and used to enhance the heat and mass transfer process of chemical heat pumps. The effects of mixing ratio and mixing method on the chemical reaction time are investigated.     

A Numerical Study on the Heat Transfer Enhancement Behavior of Water-Microparticles Suspension

The heat transfer enhancement characteristics of water with polystyrene particles are examined in the present numerical study. The numerical study is conducted in the hydrodynamically fully developed turbulent flows within a circular duct with the wall boundary condition of a constant heat flux. The thermal conductivity of the turbulent flow obtained by the Reynolds analogy is 1000 times as much as the thermal conductivity of water. On the contrary, the enhancement of thermal conductivity caused by water-microparticles suspension is relatively low. Slight enhancements of the local Nusselt number are obtained in the numerical calculations of Newtonian turbulent flows with the micro-convection effects, thus showing large deviations from the experimental data. The numerical results in non-Newtonian flows are in agreement with the experimental data. Thus, the main cause for the enhancement of the heat transfer of the suspension might be not due to the micro-convection effects but to the non-Newtonian effects     

Numerical investigation and analysis of heat transfer enhancement in channel by longitudinal vortex based on field synergy principle

3-D numerical simulations were presented for laminar flow and heat transfer characteristics in a rectangular channel with vortex generators. The effects of Reynolds number (from 800 to 3 000), the attack angle of vortex generator (from 15° to 90°) and the shape of vortex generator were examined. The numerical results were analyzed based on the field synergy principle. It is found that the inherent mechanism of the heat transfer enhancement by longitudinal vortex can be explained by the field synergy principle, that is, the second flow generated by vortex generators results in the reduction of the intersection angle between the velocity and fluid temperature gradient. The longitudinal vortex improves the field synergy of the large downstream region of longitudinal vortex generator (LVG) and the region near (LVG); however, transverse vortex only improves the synergy of the region near vortex generator. Thus, longitudinal vortex can enhance the integral heat transfer of the flow field, while transverse vortex can only enhance the local heat transfer. The synergy angle decreases with the increase of Reynolds number for the channel with LVG to differ from the result obtained from the plain channel, and the triangle winglet performs better than the rectanglar one under the same surface area condition. __________ Translated from Journal of Xi’an Jiaotong University, 2006, 40(9): 996–1000 [译自: 西安交通大学学报]