Numerical Simulation of 3—D Temperature Distribution of the Flame Tube of the Combustion Chamber with Air Film COoling

ＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆ３－ＤＴｅｍｐｅｒａｔｕｒｅＤｉｓｔｒｉｂｕｔｉｏｎｏｆｔｈｅＦｌａｍｅＴｕｂｅｏｆｔｈｅＣｏｍｂｕｓｔｉｏｎＣｈａｍｂｅｒｗｉｔｈＡｉｒＦｉｌｍＣｏｏｌｉｎｇＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆ３－Ｄ...     

Influence of Heating Rate on the Onset of Oscillation in Liquid Bridge of Half Floating Zone

ＩｎｆｌｕｅｎｃｅｏｆＨｅａｔｉｎｇＲａｔｅｏｎｔｈｅＯｎｓｅｔｏｆＯｓｃｉｌｌａｔｉｏｎｉｎＬｉｑｕｉｄＢｒｉｄｇｅｏｆＨａｌｆＦｌｏａｔｉｎｇＺｏｎｅ￥Ｊｉｎｇ－ＣｈｅｎｇＸｉｅ；Ｗｅｎ－ＲｕｉＨｕ（ＩｎｓｔｉｔｕｔｅｏｆＭｅｃｈａｎｉｃｓ，Ｃｈ...     

Local Non－Similarity Solution of Coupled Heat－Mass Transfer of a Flat Plate with Uniform Heat Flux in a Laminar Parallel Flow

ＬｏｃａｌＮｏｎ－ＳｉｍｉｌａｒｉｔｙＳｏｌｕｔｉｏｎｏｆＣｏｕｐｌｅｄＨｅａｔ－ＭａｓｓＴｒａｎｓｆｅｒｏｆａＦｌａｔＰｌａｔｅｗｉｔｈＵｎｉｆｏｒｍＨｅａｔＦｌｕｘｉｎａＬａｍｉｎａｒＰａｒａｌｌｅｌＦｌｏｗＹｕｗｅｎＺｈａｎｇ；ＺｈｏｎｇｑｉＣ...     

A High—Resolution Hybrid Scheme for solving Three Dimensional Euler Equations of High Speed Inlet Flows

ＡＨｉｇｈ－ＲｅｓｏｌｕｔｉｏｎＨｙｂｒｉｄＳｃｈｅｍｅｆｏｒＳｏｌｖｉｎｇＴｈｒｅｅＤｉｍｅｎｓｉｏｎａｌＥｕｌｅｒＥｑｕａｔｉｏｎｓｏｆＨｉｇｈＳｐｅｅｄＩｎｌｅｔＦｌｏｗｓＷａｎｇＢａｃ－Ｇｕｏ；ＬｉｕＱｉｕ－Ｓｈｅｎｇ（ＣＦＤＢｒａｎｃｈ，Ｄ...     

Numerical Simulation of 3—D Turbulent Gas—Particle FLows In a Nonslagging Cyclone COmbustor

ＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆ３－ＤＴｕｒｂｕｌｅｎｔＧａｓ－ＰａｒｔｉｃｌｅＦｌｏｗｓＩｎａＮｏｎｓｌａｇｇｉｎｇＣｙｃｌｏｎｅＣｏｍｂｕｓｔｏｒ￥ＢｉａｏＺｈｏｕ，ＷｅｎｙｉＬｉｎ，ＬｉｘｉｎｇＺｈｏｕ（ＤｅｐａｒｔｍｅｎｔｏｆＥｎｇ...     

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

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

Research and Development on PFBC—CC in China and Jiawnag Pilot plant Project

ＲｅｓｅａｒｃｈａｎｄＤｅｖｅｌｏｐｍｅｎｔｏｎＰＦＢＣ－ＣＣｉｎＣｈｉｎａａｎｄＪｉａｗａｎｇＰｉｌｏｔＰｌａｎｔＰｒｏｊｅｃｔＮｉｎｇｓｈｅｎｇＣａｉ；ＭｉｎｇｙａｏＺｈａｎｇ；ＤａｎＬｉ；ＷｅｎｔｉｎｇＦｕ（ＴｈｅｒｍａｌＥｎｅｒｇｙＥｎｇｉｎ...     

Three Dimensional Transient Coupled Radiative—Conductive Heat Transfer in Cylinders Filled with Semi—Transparent Media with Complicated Surface Characteristics

ＴｈｒｅｅＤｉｍｅｎｓｉｏｎａｌＴｒａｎｓｉｅｎｔＣｏｕｐｌｅｄＲａｄｉａｔｉｖｅＣｏｎｄｕｃｔｉｖｅＨｅａｔＴｒａｎｓｆｅｒｉｎＣｙｌｉｎｄｅｒｓＦｉｌｌｅｄｗｉｔｈＳｅｍｉ－ＴｒａｎｓｐａｒｅｎｔＭｅｄｉａｗｉｔｈＣｏｍｐｌｉｃａｔｅｄＳｕｒｆａ...     

Study on Characteristics of Steady Flow Condensation Heat Transfer in a Fube Under Zero—Gravitation

ＳｔｕｄｙｏｎＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＳｔｅａｄｙＦｌｏｗＣｏｎｄｅｎｓａｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎａＴｕｂｅｕｎｄｅｒＺｅｒｏ－ＧｒａｖｉｔａｔｉｏｎＱｎＷｅｉ（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈａｒｂｉ...     

Experimental Study on Heat Transfer and Pressure Drop Characteristics of Four Types of Plate Fin－and－TUbe Heat Exchanger Surfaces

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｎＨｅａｔＴｒａｎｓｆｅｒａｎｄＰｒｅｓｓｕｒｅＤｒｏｐＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＦｏｕｒＴｙｐｅｓｏｆＰｌａｔｅＦｉｎ－ａｎｄ－ＴＵｂｅＨｅａｔＥｘｃｈａｎｇｅｒＳｕｒｆａｃｅｓ￥Ｈ．Ｊ．Ｋａｎｇ；Ｗ．Ｌ...     

Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid in Finned Tubes

The heat transfer behavior of phase change material fluid (PCM) under laminar flow conditions in circular tubes and internally longitudinal finned tubes was studied. An effective specific heat technique was used to model the phase change process. Heat transfer results for a smooth circular tube with PCM fluid were obtained under hydrodynamically and thermally fully developed conditions. Results for the finned tube were obtained using the H2 and T boundary conditions. It was determined that the Nusselt number was strongly dependent on the Stefan number, fin thermal conductivity value, and height of the fins.     

Effect of lateral fin profiles on turbulent flow and heat transfer performance of internally finned tubes

Heat transfer performance of internally finned tubes with blocked core-tube was numerically investigated by the realizable k–ε turbulence model with wall function method using a commercial software FLUENT. Three kinds of lateral fin profiles, that is, S-shape, Z-shape and V-shape, were studied and compared. The corresponding correlations of Nusselt number and friction factor for different-shape internally finned tubes were obtained. The comprehensive performances of the studied tubes were compared under identical mass flow rate, identical pumping power and identical pressure drop conditions. It was found that tubes with S-shape fins and Z-shape fins were superior to that with V-shape fins, and moreover, tube with Z-shape fins had the best performance. The fin outer curvature radius R near the inner surface of out-tube for the S-shape finned tube had appreciable effect on heat transfer, whereas the fin inner curvature radius r near the outer surface of blocked core-tube had little impact on heat transfer. Hence, when manufacturing the internally finned tube with S-shape fins, it is better to select the outer curvature radius R as smaller as possible.     

径向错列翅片管内凝结对流换热数值模拟分析

采用数值模拟方法,对径向错列翅片管内含不凝结气体水蒸气的凝结对流换热及阻力特性进行了综合分析。将编写的自定义函数(UDF)导入ANSYS FLUENT软件,对新型强化管传热性能和阻力性能进行了数值模拟,并根据管长方向壁面上蒸汽质量分数的变化情况,讨论分析了凝结过程中翅片管传热性能的变化规律。分析结果表明:与光管相比,内翅片管的强化传热效果随翅数增多、翅片换热接触面积增大而更加显著;另一方面,翅片管的流动阻力相应增大,对管路换热产生不良影响。在所研究翅型范围内16翅y=2x~2型翅片管综合强化换热效果更优;此外随着换热过程的持续,蒸汽凝结逐渐放缓;入口速度增大导致水蒸气凝结不充分,对换热效果的提升有一定制约。     

Heat transfer augmentation in 3D internally finned and microfinned helical tube

Experiments are performed to investigate the single-phase flow and flow-boiling heat transfer augmentation in 3D internally finned and micro-finned helical tubes. The tests for single-phase flow heat transfer augmentation are carried out in helical tubes with a curvature of 0.0663 and a length of 1.15 m, and the examined range of the Reynolds number varies from 1000 to 8500. Within the applied range of Reynolds number, compared with the smooth helical tube, the average heat transfer augmentation ratio for the two finned tubes is 71% and 103%, but associated with a flow resistance increase of 90% and 140%, respectively. A higher fin height gives a higher heat transfer rate and a larger friction flow resistance. The tests for flow-boiling heat transfer are carried out in 3D internally micro-finned helical tube with a curvature of 0.0605 and a length of 0.668 m. Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D internally micro-finned helical tube is increased by 40-120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance is increased by 18-119%, respectively.     

新型轴对称内翅管换热过程的数值模拟

采用数值模拟的方法,对新型整体式轴对称不等高内展翅片换热管的管内流动、换热及阻力特性进行了研究,并将模拟结果分别与实验测量值和光管经验公式计算值进行了比较,结果表明:数值模拟结果与实验测量结果和经验公式计算结果符合得较好;新型内翅片管的强化换热效果最好,其换热系数约为光管的1.67~2.27倍,为中心对称翅片管的1.17~1.35倍;内翅片管的阻力系数是光管的1.44~2.20倍,中心对称和新型内翅片管具有基本相同的阻力系数;8翅和10翅新型内翅片管的综合性能参数较优.     

椭圆翅片管空冷器流动传热特性的研究

用稳态的恒壁温法对3个椭圆翅片管空冷器和1个圆翅片管空冷器的传热和阻力特性进行了研究,得到空冷器空气侧的传热与阻力性能,在相同的迎风面流速下,椭圆翅片管比圆翅片管空气侧换热系数约大3－7倍;在相同的换热系数下,椭圆翅片管比圆翅片管的压降低。     

不同材质花瓣形扁通道内翅换热管的实验研究

通过实验的方法研究了一种花瓣形扁通道内翅换热管的对流换热和阻力特性,拟合了所测Re范围内对流换热和阻力实验关联式,并运用相同质量流量、相同泵功率和相同阻力降这3种准则比较了采用不同材质时翅片管与普通光管之间的传热效果。结果表明,翅片材质对换热强化效果有较大影响,无论采用哪种材质,花瓣形扁通道内翅管均有较强的换热效果,特别是在低盅条件下,强化效果更加明显。     

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In this study, fully developed laminar flow and convective heat transfer in an internally finned tube heat exchanger are investigated numerically. The flow is assumed to be both hydrodynamically and thermally developed with uniform outside wall temperature. Parameters of the thickness, length, and number of fins and thermal conductivity ratio between fin and working fluid are varied to obtain the friction factor as well as Nusselt number. The results show that the heat transfer improves significantly if more fins are used; however, the pressure drop turns out to be large in this heat exchanger. In addition, it is found that the emergence of closed-loop isotherms between the areas of two neighboring fins leads to heat transfer enhancement in the internally finned tube. When the fin number is smaller than 14, there appears a maximum Nusselt number at about 0.8 of the dimensionless fin length. Finally, an experiment is conducted to verify the numerical results.     

A numerical study of flow and heat transfer in internally finned rotating straight pipes and stationary curved pipes

In this article the effects of internal fins on laminar incompressible fluid flow and heat transfer inside rotating straight pipes and stationary curved pipes are numerically studied under hydrodynamically and thermally fully developed conditions. The fins are assumed to have negligible thickness with the same conditions as the pipe walls. Two cases, constant wall temperature and constant heat flux at the wall, are considered. First the accuracy of the numerical code written by a finite volume method based on SIMPLE algorithm is verified by the available data for the finless rotating straight pipes and stationary curved pipes, and then, the numerical results for those internally finned pipes are investigated in detail. The numerical results for different sizes and numbers of internal fins indicate that the flow and temperature field analogy between internally finned rotating straight pipes and stationary curved pipes still prevail. The effects of Dean number (K_L) versus friction factor, Nusselt number, and other non-dimensional parameters are studied in detail. From the numerical results obtained, an optimum fin height about 0.8 of pipe radius is determined for Dean numbers less than 100. At this optimum value, the heat transfer enhancement is maximum, and the heat transfer coefficient appears to be 6 times as that of corresponding finless pipes.     

Numerical study of the intensified heat transfer of an internally longitudinal ridged finned tube under pulsating flow

The turbulent pulsating flow and heat transfer in an internally longitudinal protuberant finned tube was numerically investigated by solving unsteady three‐dimensional elliptical Navier–Stokes equations. The realized k–? turbulent model was adopted. The dynamic behaviors of velocity field, average Nusselt number, and friction number of the internally longitudinal protuberant finned tube were numerically analyzed in a pulsating period, and it was further investigated by changing the frequency of the pulsating flow. It was found that the intensity of heat transfer enhancement increases with an increase of pulsating frequency, while the pressure drop will be increased simultaneously, the intensification of heat transfer in internally longitudinal protuberant finned tubes are gradually better than the pressure drop with an increase of pulsating frequency. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20253