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

ＡｎＥｘｐｅｒｉｍｅｎｔａｌａｎｄＮｕｍｅｒｉｃａｌＳｔｕｄｙｏｆＮａｔｕｒａｌＣｏｎｖｅｃｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎＨｏｒｉｚｏｎｔａｌＡｎｎｕｌｉｂｅｔｗｅｅｎＥｃｃｅｎｔｒｉｃＣｙｌｉｎｄｅｒｓ￥ＷａｎｇＳｕｏｆａｎｇ（Ｄｅｐａｒｔｍ...     

Unsteadiness of Shock Wave／Boundary Layer Interaction in Supersonic Cascade

ＵｎｓｔｅａｄｉｎｅｓｓｏｆＳｈｏｃｋＷａｖｅ／ＢｏｕｎｄａｒｙＬａｙｅｒＩｎｔｅｒａｃｔｉｏｎｉｎＳｕｐｅｒｓｏｎｉｃＣａｓｃａｄｅＵｎｓｔｅａｄｉｎｅｓｓｏｆＳｈｏｃｋＷａｖｅ／ＢｏｕｎｄａｒｙＬａｙｅｒＩｎｔｅｒａｃｔｉｏｎｉｎＳｕｐｅｒｓｏｎ...     

An Experimental Study on the Motion of Droplets in Flue Gas Humidification Activator with Pulse Laser Sheet Photography

ＡｎＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｎｔｈｅＭｏｔｉｏｎｏｆＤｒｏｐｌｅｔｓｉｎＦｌｕｅＧａｓＨｕｍｉｄｉｆｉｃａｔｉｏｎＡｃｔｉｖａｔｏｒｗｉｔｈＰｕｌｓｅＬａｓｅｒＳｈｅｅｔＰｈｏｔｏｇｒａｐｈｙ￥ＫｅＪｉａｎｇ；ＸｕｃｈａｎｇＸｕ；Ｘｕｅｇ...     

Acoustic Wave Prediction in Flowing Steam-Water Two-Phase Mixture

ＡｃｏｕｓｔｉｃＷａｖｅＰｒｅｄｉｃｔｉｏｎｉｎＦｌｏｗｉｎｇＳｔｅａｍ－ＷａｔｅｒＴｗｏ－ＰｈａｓｅＭｉｘｔｕｒｅＸｕＪｉｎｌｉａｎｇ；ＣｈｅｎＴｉｎｇｋｕａｎ（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＭｕｌｔｉｐｈａｓｅＦｌｏｗｉｎＰｏｗｅｒＥｎ...     

An Approximate Model of Microchannel Cooling

ＡｎＡｐｐｒｏｘｉｍａｔｅＭｏｄｅｌｏｆＭｉｃｒｏｃｈａｎｎｅｌＣｏｏｌｉｎｇ￥ＳｈｉｐｉｎｇＹｕ；ＭｉｎｇｄａｏＸｉｎ（ＩｎｓｔｉｔｕｔｅｏｆＥｎｇｉｎｅｅｒｉｎｇＴｈｅｒｍｏｐｈｙｓｉｃｓ，ＣｈｏｎｇｑｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｃｈｏｎｇｑｉｎ...     

On Effectiveness and Entropy Generation in Heat Exchanger

ＯｎＥｆｆｅｃｔｉｖｅｎｅｓｓａｎｄＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎｉｎＨｅａｔＥｘｃｈａｎｇｅｒＯｎＥｆｆｅｃｔｉｖｅｎｅｓｓａｎｄＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎｉｎＨｅａｔＥｘｃｈａｎｇｅｒ￥ＸｉｏｎｇＤａｘｉ；ＬｉＺｈｉｘｉｎ；ＧｕｏＺｅ...     

Simulating Experimental Investigation on the Safety of Nuclear Heating Reactor in Loss—of —Coolant Accidents

ＳｉｍｕｌａｔｉｎｇＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅＳａｆｅｔｙｏｆＮｕｃｌｅａｒＨｅａｔｉｎｇＲｅａｃｔｏｒｉｎＬｏｓｓ－ｏｆ－ＣｏｏｌａｎｔＡｃｃｉｄｅｎｔｓＳｉｍｕｌａｔｉｎｇＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇ...     

An Experimental Study on 3—D Flow in an Annular Cascade of High Turning Angle Turbine Blades

ＡｎＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｎ３－ＤＦｌｏｗｉｎａｎＡｎｎｕｌａｒＣａｓｃａｄｅｏｆＨｉｇｈＴｕｒｎｉｎｇＡｎｇｌｅＴＵｒｂｉｎｅＢｌａｄｅｓ￥ＷａｎｇＷｅｎｓｈｅｎｇ；ＬｉａｎｇＸｉｚｈｉ；ＣｈｅｎＮａｉｘｉｎｇ（Ｉｎｓｔｉｔｕｔｅｏｆ...     

Experimental Studies on Heat Transfer in the Tip Gap of a Sectorial Turbine Cascade

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｉｅｓｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎｔｈｅＴｉｐＧａｐｏｆａＳｅｃｔｏｒｉａｌＴｕｒｂｉｎｅＣａｓｃａｄｅＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｉｅｓｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎｔｈｅＴｉｐＧａｐｏｆａＳｅｃｔｏｒｉａ...     

An Analytical Solution of Melting around a Moving Elliptical Heat Source

ＡｎＡｎａｌｙｔｉｃａｌＳｏｌｕｔｉｏｎｏｆＭｅｌｔｉｎｇａｒｏｕｎｄａＭｏｖｉｎｇＥｌｌｉｐｔｉｃａｌＨｅａｔＳｏｕｒｃｅ￥Ｗ．Ｚ．Ｃｈｅｎ；Ｓ．Ｍ．Ｃｈｅｎｇ；Ｚ．Ｌｕｏ；Ｈ．Ｑ．Ｚｈｕ（ＨｕａｚｈｏｎｇＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅｎｃｅａｎ...     

Modeling of Droplet-Based Processing for the Production of High-Performance Particulate Materials using the Level Set Method

The dynamic and thermal processes of an Mg-Zn-Y alloy droplet's spreading and solidification are investigated using the level set method in order to understand their effects on the phase change process in a uniform droplet spray process. The level set method, driven with the solidification velocity predicted by a free dendritic growth model, is capable of tracking the evolution of the solidification front within the deformed droplet. It is found that the solidification process heavily depends on the initial thermal state of the droplet, the latent heat released during solidification, and the heat loss to the substrate. A rapid solidification occurs in the initial microseconds before a slow solidification process takes place.     

蓄能互联热泵系统相变装置熔化与凝固过程特性分析

介绍了一种新型的蓄能互联热泵系统。利用数值模拟的方法对填充石蜡C17的球型蓄热单元的熔化与凝固过程进行研究,分析了球壁温度、相变单元尺寸和相变材料初始温度三种影响因素对熔化过程和球壁温度对凝固过程的影响。通过对两个过程对比发现相变单元尺寸对相变过程影响最大,在相同温差条件下完全熔化时间少于完全凝固时间,熔化过程中始终存在的石蜡-壁面与液相石蜡-固相石蜡之间的对流换热过程增加了熔化速率。     

Analysis of solidification in the presence of high rayleigh number convection in an enclosure

A simple and convenient analysis of the process of time-dependent solidification in an enclosed liquid cooled from the side in the presence of natural convection is presented, the influence of each parameter on the process of solidification is carried out systematically. The accuracy of this model is justified by comparing its predicting values with the previous results.     

Solidification and melting behaviors and characteristics of molten salt in cold filling pipe

The solidification and melting phenomena and performances of molten salt during cold filling process in a straight pipe are numerically investigated using volume of fluid model. As the molten salt is filled into a cold pipe, the molten salt adjacent to the cold wall is rapidly cooled, and the solidification phenomena appears. After the whole pipe is filled, the solidification layer begins to melt by high temperature fluid heating. Because of the solidification layer, the flow section obviously shrinks, and the pressure loss remarkably increases. During the solidification and melting processes, the fluid temperature in the region with phase change only varies near the freezing point, and it quickly rises after the melting process. Because of the absorption or release of latent heat, the boundary heat flux of molten salt is increased in the solidification region, while it will be decreased in the melting region. As the inlet temperature rises, the pressure loss apparently decreases with the thickness of solidification layer decreasing. However, when the inlet flow velocity increases, the thickness of solidification layer decreases, but the flow resistance without phase change increases, so the pressure loss has a maximum at moderate flow velocity.     

高品质钢锭生产质量控制研究

通过钢水质量控制、凝固过程控制及退火工艺优化等研究,实现了钢中合金含量的窄成分控制、夹杂物控制和凝固结构控制,改善了钢锭的纯净度、组织均匀性和性能稳定性,稳定了生产过程控制、提高了钢锭的质量。     

Solidification process in a Glauber Salt Mixture

An investigation on the phase-change process of solidification in a Glauber Salt mixture has been conducted. Results on the visual observations of the solidification process, measurement of its rate and its dependence on the temperature are reported. Based on experimental investigation, it is concluded that the solidification is strongly affected by rate of heat transfer and weakly influenced by concentration of the anhydrous salt. Comparison of experimental results with theoretical predictions based on a simple model developed, using improved boundary layer integral method, gives good agreements.     

Effects of mould filling on evolution of the solid–liquid interface during solidification

This work presents a numerical analysis of simultaneous mould filling and phase change for solidification in a two-dimensional rectangular cavity. The role of residual flow strength and temperature gradients within the solidifying domain, caused by the filling process, on the evolution of solidification interface are investigated. An implicit volume of fluid (VOF)-based algorithm has been employed for simulating the free surface flows during the filling process, while the model for solidification is based on a fixed-grid enthalpy-based control volume approach. Solidification modeling is coupled with VOF through User Defined Functions developed in the commercial computational fluid dynamics (CFD) code FLUENT 6.3.26. Comparison between results of the conventional analysis without filling effect and those of the present analysis shows that the residual flow resulting from the filling process significantly influences the progress of the solidification interface. A parametric study is also performed with variables such as cooling rate, filling velocity and filling configuration, in order to investigate the coupled effects of the buoyancy-driven flow and the residual flow on the solidification behavior.     

铌在高碳钢凝固过程中行为特性的模型分析

以高碳钢为研究对象,建立钢液凝固过程中溶质偏析与夹杂物析出的耦合热力学模型,并通过扫描电镜及能谱分析验证了模型的精确度。利用该热力学模型,研究分析了铌的质量分数对高碳钢凝固过程中铌的赋存状态及铌化物的影响作用规律。结果表明:(1)碳化铌和固溶铌在高碳钢凝固过程中开始析出,随着碳质量分数的增大,固溶铌的浓度分布呈现先减小而后增大的趋势;(2)随着铌质量分数的增大,高碳钢中碳化铌的析出温度及析出量均有所增大,固溶铌的平均析出量逐渐增大,其中碳化铌析出量的增加十分显著。     

一种燃机叶片试板定向凝固过程的研究

明确铸件定向凝固过程中的温度变化规律．可以避免重型燃气轮机定向叶片铸造中出现的一些缺陷。文章选取了与某重型燃机第1级涡轮动叶尺寸相近的试板．采用定向凝固高温合金DZ445．研究了该试板在实际工业生产用定向结晶炉中的定向凝固过程,结果表明：在距离水冷铜盘位置〉50mm后固液界面形态将发生大的转变,温度梯度逐渐变小,〉100mm后温度梯度基本保持不变．这为后续制定叶片抽拉工艺给出了参考。该实验还通过热电偶获得的定向凝固过程中温度一时间曲线与ProCAST模拟结果基本一致．验证了模拟边界条件和设置参数的准确性．后续可以用于模拟结构复杂的叶片定向凝固过程．指导实际生产工艺.     

Role of metal foam in solidification performance for a latent heat storage unit

The current latent heat storage (LHS) units are usually poor in energy charging and discharging efficiency. Given this, a two dimensional (2D) numerical model of the energy discharging process is presented and comprehensively analyzed to predict the role of metal foam in the solidification performance of LHS units. In the model, the fractal geometry reconstructed by the fractal Brownian motion is utilized for the pore characterization of the metal foam. The proposed model is validated through a melting experiment in copper foams from the reference. The temperature dynamic response and the solidification front evolution in metal foam are analyzed and compared to those in a corresponding cavity. The roles of the fractal dimension and porosity in the solidification behaviors are quantitatively analyzed. The results report that the presence of metal foam enhances the solidification performance. For the main goal of maximizing the latent storage, the appropriate porosity of an LHS unit is dependent on the duration time for the heat discharging process in the real application of thermal energy storage. Even if the porosity is the same, the fractal dimension also affects the solidification performance. A decrease in the fractal dimension (lower degree of disorder for pore distribution) provides greater access to heat flow through the phase change material-foam composite and thus leads to improvement in the interstitial heat transfer, which in turn accelerates the rate of heat release. The fractal dimension is expected to be less than 1.5 for superior solidification performance.