Experimental Studieson Gas－Particle Flows and Coal Combustion in New Generation Spouting－Cyclone Combustor

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｉｅｓｏｎＧａｓ－ＰａｒｔｉｃｌｅＦｌｏｗｓａｎｄＣｏａｌＣｏｍｂｕｓｔｉｏｎｉｎＮｅｗＧｅｎｅｒａｔｉｏｎＳｐｏｕｔｉｎｇ－ＣｙｃｌｏｎｅＣｏｍｂｕｓｔｏｒＤ．Ｘ．Ｗａｎｇ；Ｚ．Ｈ．Ｍａ；Ｘ．Ｌ．Ｗａｎｇ；Ｌ．Ｘ．Ｚ...     

A Modified Entropy Generation Number for Heat Exchangers

ＡＭｏｄｉｆｉｅｄＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎＮｕｍｂｅｒｆｏｒＨｅａｔＥｘｃｈａｎｇｅｒｓＡＭｏｄｉｆｉｅｄＥｎｔｒｏｐｙＧｅｎｅｒａｔｉｏｎＮｕｍｂｅｒｆｏｒＨｅａｔＥｘｃｈａｎｇｅｒｓ￥Ｚ．Ｍ．Ｘｕ；Ｓ．Ｒ．Ｙａｎｇ（Ｄｅｐａｒｔｍｅｎｔ...     

Molecular Dynamics Simulation on Thermodynamic Properties and Transport Coefficients

ＭｏｌｅｃｕｌａｒＤｙｎａｍｉｃｓＳｉｍｕｌａｔｉｏｎｏｎＴｈｅｒｍｏｄｙｎａｍｉｃＰｒｏｐｅｒｔｉｅｓａｎｄＴｒａｎｓｐｏｒｔＣｏｅｆｆｉｃｉｅｎｔｓＤ．Ｘ．Ｘｉｏｎｇ；Ｙ．Ｓ．Ｘｕ，Ｚ．Ｙ．Ｇｕｏ（ＤｅｐａｒｔｍｅｎｔｏｆＥｎｇｉｎｅｅｒｉｎｇＭ...     

High Heat Flux Burnout in Subcooled Flow Boiling

ＨｉｇｈＨｅａｔＦｌｕｘＢｕｒｎｏｕｔｉｎＳｕｂｃｏｏｌｅｄＦｌｏｗＢｏｉｌｉｎｇＧ．Ｐ．Ｃｅｌａｔａ；Ｍ．Ｃｕｍｏ；Ａ．Ｍａｒｉａｎｉ（ＥＮＥＡＥｎｅｒｇｙＤｅｐａｒｔｍｅｎｔ，ＶｉａＡｎｇｕｉｌｌａｒｅｓｅ，３０１Ｉ－０００６０Ｓ．Ｍ．Ｇａｌｅｒ...     

On The Analysis of Labyrinth Seal Flow Induced Vibration by Oscillating Fluid Mechanics Method

ＯｎＴｈｅＡｎａｌｙｓｉｓｏｆＬａｂｙｒｉｎｔｈＳｅａｌＦｌｏｗＩｎｄｕｃｅｄＶｉｂｒａｔｉｏｎｂｙＯｓｃｉｌｌａｔｉｎｇＦｌｕｉｄＭｅｃｈａｎｉｃｓＭｅｔｈｏｄ￥ＣｈｅｎＺｕｏｙｉ；ＪｉｎｇＹｏｕｈａｏ；ＳｕｎＹｏｎｇｚｈｏｎｇ（Ｄｅａｔｈ．ｏｆＴ...     

Boundary Layer Ignition of Hydrogen-Air Mixtures in Supersonic Flows

ＢｏｕｎｄａｒｙＬａｙｅｒＩｇｎｉｔｉｏｎｏｆＨｙｄｒｏｇｅｎ－ＡｉｒＭｉｘｔｕｒｅｓｉｎＳｕｐｅｒｓｏｎｉｃＦｌｏｗｓ￥Ｌ．Ｆ．Ｆｉｇｕｅｉｒａ；ｄａＳｉｌｖａ；Ｂ．Ｄｅｓｈａｉｅｓ；Ｍ．Ｃｈａｍｐｉｏｎ（Ｌａｂｏｒａｔｏｉｒｅｄ＇Ｅｎｅｒｇｅｔｉ...     

Effects of Coal—Water Mixture Properties in Atomization

ＥｆｆｅｃｔｓｏｆＣｏａｌ－ＷａｔｅｒＭｉｘｔｕｒｅＰｒｏｐｅｒｔｉｅｓｉｎＡｔｏｍｉｚａｔｉｏｎ￥ＤａｖｉｄＪ．Ｗｉｌｄｍａｎ；ＪａｍｅｓＭ．Ｅｋｍａｎｎ（ＰｉｔｔｓｂｕｒｇｈＥｎｅｒｇｙＴｅｃｈｎｏｌｏｇｙＣｅｎｔｅｒ，Ｕ．Ｓ．Ｄｅｐａｒｔｍｅｎ...     

An Analytical and Experimental Study of a Natural Circulation Loop with Horizontal Heating Section

ＡｎＡｎａｌｙｔｉｃａｌａｎｄＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｆａＮａｔｕｒａｌＣｉｒｃｕｌａｔｉｏｎＬｏｏｐｗｉｔｈＨｏｒｉｚｏｎｔａｌＨｅａｔｉｎｇＳｅｃｔｉｏｎ￥ＹｉｎｘｕｅＳｕ；ＱｉｎｇｊｉｎＷｕ（ＤｅｐａｒｔｍｅｎｔｏｆＰｏｗｅｒＭａｃ...     

An Approximate Model of Microchannel Cooling

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

Comparison of a Reaction Front Model and a Finite Difference Model for the Simulation of Solid Absorption Process

ＣｏｍｐａｒｉｓｏｎｏｆａＲｅａｃｔｉｏｎＦｒｏｎｔＭｏｄｅｌａｎｄａＦｉｎｉｔｅＤｉｆｆｅｒｅｎｃｅＭｏｄｅｌｆｏｒｔｈｅＳｉｍｕｌａｔｉｏｎｏｆＳｏｌｉｄＡｂｓｏｒｐｔｉｏｎＰｒｏｃｅｓｓ￥ＺｉｋａｎｇＷｕ；ＡｒｎｅＪａｋｏｂｓｅｎ；Ｘｉｕｇａｎ...     

Analysis of contact melting driven by surface heat flux around a cylinder

The contact melting of phase change material around a moving horizontal cylindrical heat source, which descended under its own weight, is investigated in this article. A melting model under constant surface heat flux is established. The analytical results for thickness and pressure distributions inside melt layer and steady melting velocity are obtained by using contact melting theory. The melting law is discussed, and compared with that of contact melting driven by temperature difference. It is found that quasi-steady melting velocity is determined by heat flux of heat source, and the variation of heat source density has less effect on melting velocity.     

Modeling Yin—Yang Balance in Tai—Chi Diagram with a Melting—Freezing Rotating Device

InttoductionTai-chi diW is a symboI of wisdom in theChinese history, and is a very influential diagram in theWhole Chinese civilization. However, there is littlescientific research wOrk available in the literatUre thatprovides a physical model that can describe and interprethe yin-yang balance in the tai-chi diagram.The Presen stUdy is in an atteInPt to interpret theyin-yang balance in the tai--chi dign with a stwleNcal 1angUage through the Physical Processes ofmelhng and freezing in a r…     

Analytical solution of transient heat transfer with variable source for applications in nuclear reactors

The volumetric heat source in a nuclear fuel element, may vary with time and/or with space for an uncontrolled operating condition. The time required to attain the melting point of the cladding material was determined considering two trial variations of the source term, one with time only and the other with time and space as well. A general analytical solution for this transient heat transfer problem with variable source that can take care of any functional variations of source is presented. The dependence of the time required for melting of the cladding material with other parameters, e.g., Biot number, source strength, etc. are also investigated.     

Does nanoparticles dispersed in a phase change material improve melting characteristics?

Nanoparticles dispersed in a phase change material alter the thermo-physical properties of the base material, such as thermal conductivity, viscosity, and specific heat capacity. These properties combined with the configuration of the cavity, and the location of the heat source, influence the melting characteristics of the phase change material. In this paper, an assessment of the influence of the nanoparticles in the base material subjected to a heat generating source located in the center of an insulated square cavity, which is a common configuration in thermal capacitors for temporal heat storage is investigated. The interplay between heat conduction enhanced due to an increase in thermal conduction and buoyancy driven heat convection damped by the increase in viscosity of nanoparticles dispersed in the phase change materials is studied with the calculated streamlines and isotherms. We observed three regimes during the melting process, first at an early time duration dominated by heat conduction, later by buoyancy driven convection till the melting front levels with the center of the cavity, and lastly once again heat conduction in the bottom portion of the cavity. During the first two regimes, addition of nanoparticles have no significant performance gain on the heat storage cavity, quantified by maximum temperature of the heat source and average Nusselt number at the faces of the heat source. In the late regime, nanoparticles provide a slight performance gain and this is attributed to the increase in the specific heat of the melt due to the nanoparticles.     

Study of direct contact melting with hydrocarbon mixtures as the PCM

In this study, direct contact melting of hydrocarbon mixtures as phase change materials was investigated experimentally. Tetradecane and hexadecane binary mixtures, and pentadecane and octadecane binary mixtures were used as phase change materials, with various mixing ratios. It was found that the heat flux decreased significantly in the low surface temperature range. In addition, a rough and uneven melting surface was observed in the low surface temperature range. The convex portions at the melting surface were collected, and the ingredients of this region were measured by using differential scanning calorimetry (DSC). It was found that the DSC curve shifted to a higher temperature region, and the concentration of higher melting point material increased at the convex portions. Therefore, it seems that the melting point around the convex portions increased due to the higher concentration of higher melting point material, and this resulted in the decrease in the heat flux.     

Melting of a semi-infinite solid with a volume distributed substrate heat source

The analysis of the melting of a semi-infinite slab initially at its melting temperature with a heat source, volume distributed within a supporting substrate layer, is performed by the heat balance integral method.     

Melting in a side heated tall enclosure by a uniformly dissipating heat source

Melting of an organic phase change material (PCM) n-triacontane (C₃₀H₆₂) in a side heated tall enclosure of aspect ratio 10, by a uniformly dissipating heat source has been studied computationally and experimentally. While heat transfer data for melting in enclosures under isothermal wall boundary condition are available in the literature, other boundary conditions, such as constant heat flux often arise in applications of PCM for transient thermal management of electronics. An implicit enthalpy–porosity approach was utilized for computational modeling of the melting process. Experimental visualization of melt front locations was performed. Comparisons between experimental and computational heat transfer data and melt interface locations were good. Fluid flow and heat transfer characteristics during melting suggested that natural convection plays a dominant role during initial stages of melting. At later times, the strength of natural convection diminishes as melting is completed. Correlations of heat transfer rate and melt fraction with time were obtained.     

Numerical Investigation of Phase Change Material-Based Heat Storage Unit on Cooling of Mobile Phone

This article presents the cooling of mobile phones using phase change material stored in a heat storage unit (HSU). In this study, the cooling performances of three HSU models at different power levels are examined using numerical simulation. Results show that for the same magnitude of heat source power, the melting start time and charging times can be extended if the heat sources and HSUs are distributed. Dimensional analysis shows that the melt fraction can be plotted against the product of Fourier and Stefan numbers to produce some generalized results for cases with low heat source power. At higher power, the Rayleigh number has to be included to take into account the effect of convection. The article also compares the heat source temperatures between plastic and aluminum enclosures.     

Effect of internal void placement on the heat transfer performance – Encapsulated phase change material for energy storage

The effect of an internal air void on the heat transfer phenomenon within encapsulated phase change material (EPCM) is examined. Heat transfer simulations are conducted on a two dimensional cylindrical capsule using sodium nitrate as the high temperature phase change material (PCM). The effects of thermal expansion of the PCM and the buoyancy driven convection within the fluid media are considered in the present thermal analysis. The melting time of three different initial locations of an internal 20% air void within the EPCM capsule are compared. Latent heat is stored within an EPCM capsule, in addition to sensible heat storage. In general, the solid/liquid interface propagates radially inward during the melting process. The shape of the solid liquid interface as well as the rate at which it moves is affected by the location of the internal air void. The case of an initial void located at the center of the EPCM capsule has the highest heat transfer rate and thus fastest melting time. An EPCM capsule with a void located at the top has the longest melting time. Since the inclusion of a void space is necessary to accommodate the thermal expansion of a PCM upon melting, understanding its effect on the heat transfer within an EPCM capsule is necessary.     

间歇性大功率相变热沉研究

针对某300W大功率间歇式热源，选用9wt%膨胀石墨-56号石蜡复合材料作相变工质，铝翅片作导热结构，基于Fluent软件，采用等效比热容数学模型，在安全温度为65℃情况下，设计得到能稳定运行3500s的相变热沉。针对该相变热沉，为验证等效比热容数学模型的可靠性，搭建了相变热沉测试系统，研究了热源功率及相变工质对热沉控温性能的影响。结果表明：等效比热容数学模型有效可靠；相变材料熔点越低，相变热沉温控时间越长；而热源输入功率越高，相变工质熔点的影响将变小。此外，为降低系统内部温差、减少石蜡泄露以及降低加工成本，进一步提出了热管-回转式翅片相变热沉，热管-回转式翅片相变热沉在热源功率为300W条件下，温控时间高达4300s，内部温差仅在1.6℃以内。