摘要:

The transient heat and mass transfer occurring in a regenerative closed-cycle adsorption cooling/heating system is governed by coupled nonlinear hyperbolic equations. These equations are solved by means of an iterative numerical scheme based on physical arguments. The numerical solution is used to carry out a parametric study of the effect of various design parameters and operating conditions on the system performance, including the evaporator and condenser temperatures and inert material thermal capacitance.

ISSN:1040-7782    

DOI:10.1080/10407789208944862

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper presents performance tests of a higher-order turbulence closure model for the predictions of turbulent shear flows. Computations of the momentum and temperature fields in the flow domain being considered entail the solutions of the Reynolds-averaged transport equations containing the second-order turbulence fluctuating products. Computations of the Reynolds stresses are performed with three closure models and the k-c model (one of the Boussinesq viscosity models). Computations of the second-order temperature velocity products are achieved by closing the pressure-heat flux term. These predictions are compared with three sets of experimental data. Several advantages have been observed in using the higher-order transport equations for evaluating Reynolds stresses; considerable improvement is achieved when higher-order turbulence closures are employed. This is because the Boussinesq viscosity model assumes that turbulence is isotropic and thus overpredicts the transverse normal component of the Reynolds stresses.

ISSN:1040-7782    

DOI:10.1080/10407789208944863

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A numerical study of natural convection heal transfer has been conducted for air around two horizontal heated cylinders confined to a rectangular enclosure cooled from above. Two cavity widths and three different top cylinder positions were investigated. The local and average Nusselt numbers are determined over the range of Rayleigh numbers from 10* to Iff. Results show the complexity of convective motion for different geometric configurations and the effects of the cylinder positions and the Rayleigh number on the local and overall heat transfer rates.

ISSN:1040-7782    

DOI:10.1080/10407789208944864

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The conjugate gradient method is used to solve the inverse problem of determining the spacewise variation of an unknown applied wall flux for laminar flow inside a parallel plate duct. One of the walls is insulated. The inverse analysis is based on the temperature reading taken inside the fluid at several different locations along the flow. The inverse analysis is performed by using the combination of the regular and modified conjugate gradient methods. The combined method was found to be more accurate than either of these two methods alone.

ISSN:1040-7782    

DOI:10.1080/10407789208944865

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Improvements in the theoretical model and computational procedure for the prediction of film height and heat transfer coefficient of the free surface flow of a radially spreading thin liquid film adjacent to aflat horizontal surface of finite extent are presented. Flows in the presence and absence of gravity are considered. Theoretical results are compared to available experimental data with good agreement. In the presence of gravity, a hydraulic jump is present, isolating the flow into two regimes: supercritical upstream from the jump and subcritical downstream. In this situation, the effects of surface tension are important near the outer edge of the disk where the fluid experiences free fall. A region of flow separation is present just downstream of the jump. In the absence of gravity, no hydraulic jump or separated flow region is present. The variation of the heat transfer coefficient for flows in the presence and absence of gravity is also presented.

ISSN:1040-7782    

DOI:10.1080/10407789208944866

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper investigates combined laminar forced convection and radiation heat transfer of an absorbing-emitting gas in the entrance region of an elliptic duct with internal fins. The fins are continuous and longitudinal with zero thickness. The thermal conditions imposed on the elliptic duct are uniform temperature, both axially and peripherally. The method of moments, which models radiation in a partial differential equation, is employed to consider the radiation contribution. The three-dimensional energy equation and two-dimensional irradiation equation are diseretized and numerically solved by the control-volume based finite-difference method in the boundary-fitted coordinate system. The effects of six major parameters on the thermal behavior in the entrance region of the elliptic duct is discussed. These parameters are radiation-conduction, optical thickness, wall emissivity, Picltt number, fin height, and the minor axis to major axis ratio of the elliptic duct. The total Nusselt number variations show that heat transfer is enhanced by both thermal radiation and juts. Furthermore, the results are compared with the available data in the literature for pure forced convection with fins. We prove that radiation plays a significant role in the enhancement of heat transfer.

ISSN:1040-7782    

DOI:10.1080/10407789208944867

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The radiant barrier effectiveness of ceramic liners for diesel engine cylinders is investigated through a high-order radiative transfer model coupled to a finite-difference solution of the energy equation. The results are compared with those from an earlier study that used the two-flux method. The two-flux results are found to be in error by up to 13%, but the qualitative conclusions of the earlier study are still valid.

ISSN:1040-7782    

DOI:10.1080/10407789208944868

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor