摘要:

It is proposed that researchers in the numerical heat transfer community need to realize the trend of the information highway and agree to use a protocol or a module that constitutes the core of a computer program solving heat transfer problems. This will avoid duplicate programming and accelerate the technology advancement of numerical heat transfer. The module for two-dimensional incompressible Navier-Stokes flows is presented and explained. It is further demonstrated that, using this module as the foundation, the user can straightforwardly build up an entire personal computer code by inputting the data, specifying boundary conditions, and outputting the result. Other modules for slightly more compicated problems, such as transient flows with variable viscosity in irregular geometries, are also presented. Other than zoning matches for problems with multizones, the programming task for a user becomes minimal and simple: input, prescribe the boundary conditions, and output. The availability of Navier-Stokes modules is particularly helpful for less experienced numerical researchers, newcomers, and graduate students who have just entered the area of heat transfer and fluid flows.

ISSN:1040-7782    

DOI:10.1080/10407789608913862

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Transient numerical analysis was carried out for the replacement process of cold fluid with hot fluid in a thermal storage water tank with a two-dimensional two-equation turbulence model (k−ϵ model). The QUICKEST (QUICK with estimated streaming terms) method was two-dimensionalb) extended to solve the energy equations. The effect of the difference schemes (the QUICKEST scheme and the upwind scheme) to solve the energy equations was discussed on the transient flow and temperature fields. Comparison with existing experimental results showed that the present numerical approach can fairly predict the characteristics of thermal stratification in a thermal storage water tank.

ISSN:1040-7782    

DOI:10.1080/10407789608913863

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A new thermal storage system using multiple phase change materials (PCMs) is developed. It consists of several shell-and-tube thermal storage exchangers, which are connected in series to improve the system efficiency. Each exchanger uses a different PCM. To reach optimal system efficiency, the melting points of the PCMs are carefully selected according to a thermodynamic optimization-analysis. A finite element model is developed to simulate the cyclic thermal process in the multi-exchanger system. Compulations were carried out for a three-exchanger system to investigate the advantages of the multiple-PCM system over the conventional single-PCM system. Simulation results were compared and found to be in good agreement with the results of a thermodynamic optimization analysis.

ISSN:1040-7782    

DOI:10.1080/10407789608913864

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Recent progress in numerical modeling of the transient heat transport and fluid flow in the GTE GaAs space experiment is reported. The vertical gradient freeze crystal growth system is simulated using a simplified axisymmetric finite element model. The enthalpy method is used to model the phase change, and numerical solutions are computed on a fixed grid using the CFD code FIDAP. The numerical results suggest that the shape and melt-back position of the meti-crystal interface are greatly affected by the melting history, therefore making it necessary to model the whole melting and solidification process. The simulated interface evolution for the flight experiment predicts a delay of about 25 min for the actual growth to start after the power reduction begins, which is in good agreement with the experiment. Some numerical issues, such as the advantages and limitations of the fixed domain approach, are also discussed.

ISSN:1040-7782    

DOI:10.1080/10407789608913865

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A numerical study was performed on buoyant flow and heat transfer in vertical plate-fin heat sinks. As a result of the problem's importance, a number of semiempirical correlations have been proposed to determine the Nusselt number along the wetted surfaces and establish the optimum fin spacing. This article aims to assess the accuracy and range of applicability of such correlations. A CFD program CoolitTMspecifically designed for modeling electronic equipment, was used to predict heat transfer over a wide range of Raleigh numbers and geometrical parameters. The computed results are presented and compared with semiempirical correlations. Ranges of validity of the correlations and three-dimensional flow mechanisms responsible for the observed discrepancies are discussed.

ISSN:1040-7782    

DOI:10.1080/10407789608913866

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The shape factors for steady state, two-dimensional heat transfer across long polygonal fibers in a matrix are computed by a numerical conformal transformation procedure. The coordinate transformation functions in the complex plane and the heat conduction shape factors are expressed in a closed form, but the final results require numerical integration. The semi-analytic approach is a general solution, in the sense that it encompasses many specific geometries such as concentric square regions and concentric hexagonal regions.

ISSN:1040-7782    

DOI:10.1080/10407789608913867

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The discrete-ordiaate method using composite quadrature is extended to analyze radiative transfer in a two-layer scattering medium with Fresnet interfaces. Since the discrete ordinates used in the present method depend on the critical angles at the interfaces, the discrete ordinates for each of the two layers may be different. Thus a technique adopting the formal solution of the radiation intensity leaving the interface from one layer to determine the intensity on the discrete ordinates of the other is presented. We apply the technique to obtain the hemispherical reflectivity and transmissivity of a two-layer medium. The effects of albedos, refractive indices, and various reflecting models at the lower surface of the medium are investigated.

ISSN:1040-7782    

DOI:10.1080/10407789608913868

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor