Browsing by Author "Ke, WW"

Now showing 1 - 5 of 5

An investigation of a block moving back and forth on a heat plate under a slot jet
(2001-07-01)
Fu, WS
;
Wang, KN
;
Ke, WW
;
機械工程學系
;
Department of Mechanical Engineering
An investigation of heat transfer rate of a heat plate under a slot jet was studied numerically. For enhancing the heat transfer rate of the heat plate, a block moves back and forth on the heat plate. Then the thermal boundary layer on the heat plate is destroyed by the moving block and a new thermal boundary layer reforms immediately as the block passes through. Consequently, the remarkable heat transfer enhancement of the heat plate is attained. This subject belongs to a kind of moving boundary problems, the modified arbitrary Lagrangian Eulerian (ALE) method is suitable for solving this subject. The results show that the maximum increment of heat transfer rate is about 200% in the largest velocity case. (C) 2001 Elsevier Science Ltd. All rights reserved.
Effects of a random porosity model on double diffusive natural convection in a porous medium enclosure
(2000-01-01)
Fu, WS
;
Ke, WW
;
機械工程學系
;
Department of Mechanical Engineering
A double diffusive natural convection in a rectangular enclosure filled with porous medium is investigated numerically. The distribution of porosity is based upon the random porosity model The Darcy-Brinkman-Forchheimer model is used and the factors of heat flux, mean porosity and standard deviation are taken into consideration. The SIMPLEC method with iterative processes is adopted to solve the governing equations. The effects of the random porosity model on the distributions of local Nusselt number are remarkable and the variations of the local Nusselt number become disordered. The contribution of latent heat transfer to the total heat transfer of the high Rayleigh number is larger than that of the low Rayleigh number and the variations of the latent heat transfer are not in order. (C) 2000 Elsevier Science Ltd.
Evaporation of water film in an enclosure filled with a porous medium
(1999-05-01)
Fu, WS
;
Ke, WW
;
機械工程學系
;
Department of Mechanical Engineering
A double diffusive natural convection in an enclosure filled with a porous medium is investigated numerically. To enhance the heat transfer rate of a heat wall, the heat wall is wetted with a thin water film, then sensible and latent heat transfer occur simultaneously. The Darcy-Brinkman-Forchheimer model is used and the factors of heat flux, porosity and diameter of bead are taken into consideration. The SIMPLEC method with iterative processes is adopted to solve the governing equations. The results show that the effect of evaporation on the heat transfer rate is apparent, and the latent heat transfer plays an important role in the high Darcy-Rayleigh number situations. The averaged Nusselt number <(Nu)over bar> is approximately 2.5 when Ra*<4. In the range of 4
Heat transfer of porous medium with random porosity model in a laminar channel flow
(2001-07-01)
Fu, WS
;
Wang, KN
;
Ke, WW
;
機械工程學系
;
Department of Mechanical Engineering
In this paper, force convection heat transfer of a porous medium in a laminar channel flow is numerically investigated. The porous medium with random porosities is used to enhance heat transfer and the random porosities are derived by the Kinderman-Ramage procedure. The results show that when the mean porosity is larger than 0.5, the average Nusselt numbers are enhanced and better than the solid block case. Therefore, a porous medium with larger porosity and the proper bead diameter could provide more heat dissipation. For the random porosity distribution, the profiles of velocities are disordered and the channeling effect is not apparent near the plate region.
Laminar forced convection in a channel with a moving block
(2001-07-01)
Fu, WS
;
Ke, WW
;
Wang, KN
;
機械工程學系
;
Department of Mechanical Engineering
Heat transfer rate in a channel with an insulated moving block on a heated surface was studied numerically. For enhancing the heat transfer rate of the heated surface, the block moves back and forth on the heated surface. Then the thermal boundary layer attached to the heated surface is destroyed by the moving block and a new thermal boundary layer reforms immediately as the block passes through. Consequently, a remarkable heat transfer enhancement of the heated surface is attained. This subject belongs to a kind of moving boundary problems, and the modified Arbitrary Lagrangian Eulerian method is suitable for solving this subject. The results show that the maximum increment of heat transfer rate is about 98% in the study. (C) 2001 Elsevier Science Ltd. All rights reserved.