摘要:

Time dependent heat transfer has been investigated in a fin assembly comprising an array of fins attached to a supporting wall. Convective heat exchange from the supporting wail and thermal interactions between the wall and fins art considered. A new implementation of the boundary element method solution technique has been devised to investigate oscillatory heat transfer in a fin assembly and is extended to investigate fin assembly heat transfer that is of a general periodic nature.

ISSN:1040-7782    

DOI:10.1080/10407789308913678

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Numerical predictions of mean and turbulent characteristics of the axisymmetric vertical jet and plume are reported. An algebraic stress and flux model is used to close the time-averaged Navier-Stokes and energy equations. Special attention was given to the numerical model, which is based on a finite-volume discretization of the elliptic form of flow equations. A special procedure is used to treat free boundaries and to compute the flow up to the similarity regime. The model was applied to the prediction of the flow for the momentum-dominated (jet) and buoyancy-dominated (plume) regime. The results show that the essential characteristics of the flows, especially for the plume, are correctly reproduced. However, some discrepancies arise from the comparison of predicted and experimental levels.

ISSN:1040-7782    

DOI:10.1080/10407789308913679

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A solution is presented for the three-dimensional heat and mass transfer during evaporation of a circular meniscus of liquid NH3flowing parallel to a gaseous NH3-H2stream, as encountered in the evaporator of small neutral gas absorption refrigerators. The procedure developed is based on a finite difference solution of a set of differential equations expressing the three-dimensional transport of momentum, heat, and mass. Expressions are also provided for the thermodynamic and transport properties of the real NH3-H2mixture. The results of the numerical solution include the fields of velocity, temperature, NH3mass fraction, enthalpy, and entropy.

ISSN:1040-7782    

DOI:10.1080/10407789308913680

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A numerical model is developed for quantitatively analyzing combined conductive and radiative heat transfer in concentric annular packed beds, A packed bed is considered to be a continuous medium for heat transfer, but the porosity distribution within a packed bed is taken into account, lb examine the validity of the proposed model, combined conductive and radiative heat transfer through annular packed beds of cordierite or porcelain beads is analyzed numerically using finite differences under conditions corresponding to heat transfer experiments of these packed beds. The resultant temperature profiles and heat transfer characteristics are compared with the experimental results.

ISSN:1040-7782    

DOI:10.1080/10407789308913681

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Mixed convection heat transfer phenomena are studied in a three-dimensional channel with a cavity heated from below. A general purpose computer program is developed to analyze the flow field and temperature distribution in the channel. Numerical computation is performed by using the alternating direction implicit (ADI) method based on the SIMPLER algorithm. The influences of Reynolds number and Grashof number on the Nusselt number of the cavity art discussed. As a convenience to the reader, three-dimensional streaklines and three-dimensional isothermal surfaces are presented.

ISSN:1040-7782    

DOI:10.1080/10407789308913682

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Mixed convection is studied numerically in the case of an isolated, constant source of heat input within a rectangular enclosure. An external flow enters the enclosure through an opening in the left vertical wall and exits from another opening in the right vertical wall. This configuration leads to a conjugate heat transfer problem and simulates the air cooling of electronic components. Various parameters arise in this problem, particularly the Reynolds number, the buoyancy parameter Gr/Re2, the ratio of the thermal conductivity of the wall material to that of the fluid taken as air, and several geometric parameters. The time-dependent continuity and Navier-Stokes equations are transformed into a system of equations with the stream function and the vorticity as the dependent variables. The energy equation is solved over the entire domain, using the corresponding properties for the solid and fluid regions. The control volume approach is employed in order to discredit the governing equations for their numerical solution. A time marching procedure is followed, until steady state is reached. Results art presented for different values of the buoyancy parameter in the laminar regime, and the critical value of Gr/Re2, i.e., the highest value that leads to a convergent steady solution, is determined. Oscillatory results characterized by a single frequency were observed as this value was exceeded, up to a point where the oscillations showed irregular patterns, indicating that the flow was approaching the turbulent regime. Of particular interest here is the heat transfer, from the heat source to the fluid and from all the inner walls (solid-fluid interfaces) to the fluid, expressed in terms of the corresponding Nusselt numbers.

ISSN:1040-7782    

DOI:10.1080/10407789308913683

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor