Flow pulsation and baffle’s effects on the opposing mixed convection in a vertical channel

Chang, Tsai-Shou; Shiau, Yann-Huei

doi:10.1016/j.ijheatmasstransfer.2004.12.015

Cited by 25 publications

(12 citation statements)

References 33 publications

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“…The experimental results by Chen and Chen (1998) showed that the local heat transfer co-efficient decreases with an increase in the baffle wall gap for small baffle widths whereas for large baffle widths the heat transfer co-efficient was increased. The effect of horizontal baffle on the heat transfer characteristics of opposing mixed convection in a vertical open channel was studied by Chang and Shiau (2005). Mixed convection in a vertical channel saturated with porous medium was studied by Umavathi et al (2014) in the presence of baffle and they found that by increasing the porous parameter, rate of heat transfer was enhanced at both the walls.…”

Section: Introductionmentioning

confidence: 99%

Effect of viscous dissipation on mixed convection flow in a vertical double passage channel using Robin boundary conditions

Kumar¹,

Umavathi²,

Prasad³

2016

Int. J. Eng. Sci. Tech

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The laminar fully developed flow in a vertical double passage channel filled with clear fluid has been discussed using Robin boundary conditions. The thin perfectly conductive baffle is inserted in the channel. The governing equations of the fluid which are coupled and nonlinear are solved analytically by the perturbation method and semi analytically using differential transform method (DTM). The reference temperature of the external fluid is considered to be equal and different. The perturbation method which is valid for small values of perturbation parameter is used to find the combined effects of buoyancy forces and viscous dissipation. The limitation imposed on the perturbation parameter is relaxed by solving the basic equations using differential transform method. The influence of mixed convection parameter, Biot number for symmetric and asymmetric wall temperatures on the velocity, temperature and the Nusselt number is explored at different positions of the baffle. The solutions obtained by differential transform method are justified by comparing with the solutions obtained by perturbation method and the solutions agree very well for small values of the perturbation parameter.

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Section: Introductionmentioning

confidence: 99%

Effect of viscous dissipation on mixed convection flow in a vertical double passage channel using Robin boundary conditions

Kumar¹,

Umavathi²,

Prasad³

2016

Int. J. Eng. Sci. Tech

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“…Rabadi et al [26] also considered laminar pulsating flow in curved tubes and found that the timeaveraged heat transfer coefficient is comparatively large for large Prandtl numbers Pr and falls at low frequencies, which is clearly shown as the oscillation amplitude increases. In [27], the influence of the Grashof number Gr and Re on heat transfer characteristics in a parallel vertical open channel was demonstrated.…”

Section: Introductionmentioning

confidence: 99%

“…Mackley et al [19] reported that the insertion of baffles into a smooth tube significantly influenced the heat transfer coefficients when compared to that of a normal smooth tube. In the work of Chang and Shiau [27], the installation of a horizontal baffle at the channel inlet in a steadily fully developed flow produced higher heat transfer over the range of Gr investigated. Tauscher and Mayinger [34] found that the performance of all the ribbed configurations investigated on heat transfer when compared to a smooth channel in the laminar flow was poor.…”

Section: Introductionmentioning

confidence: 99%

“…The influence of combining flow pulsation and sharp edges arranged in ducts on the heat transfer coefficient was considered by [19,27,[39][40][41][42][43][44][45]. In [39], a numerical study of laminar natural convection from a vertical plate with nonconducting baffles subjected to a periodic oscillation was performed.…”

Section: Introductionmentioning

confidence: 99%

“…Local heat transfer measurements for oscillatory flow in a channel with a single conducting baffle was considered in [40]. A numerical study of the effects of a horizontal baffle on the heat transfer characteristics of pulsating mixed convection in a parallel vertical open channel was described in [27]. Heat transfer performance of a periodically baffled tube subjected to oscillatory flow was investigated experimentally in [19,41,42].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Flow Pulsation on Forced Convection in a Channel Containing Regularly Spaced Nonconducting Fins

2010

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The effects of pulsating flow on forced convection in a rectangular channel containing a series of regularly spaced, nonconducting inserts were investigated experimentally. Based on the experimental data, a correlation equation was developed. The steady-flow Reynolds number Re in the laminar range, Re < 1200, was examined. The Prandtl number of the working fluid Pr = 15 and the oscillation was generated using low-frequency oscillation at f < 50 Hz and amplitude A < 1 mm. The energy dissipation as a result of applied oscillation was determined by phase-resolved measurements of pressure difference and liquid displacement. The system shows improved convective heat transfer towards a low Reynolds number. At a higher Reynolds number, the influence of the oscillation diminished and the flow approaches a steady finned flow. The predictions of the developed correlation equation are in good agreement with the experimental data. The calculated power input due to oscillation is comparatively low and decreases towards increasing net flow rates where the oscillating flow has a diminishing effect.

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CFD Study of Effects of Module Geometry on Forced Convection in a Channel with Non‐Conducting Fins and Flow Pulsation

2010

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CFD simulations were carried out to investigate the effects of the module geometry on forced convection in a rectangular channel containing series of regularly spaced non-conducting baffles with flow oscillation. The simulations were performed at constant wall temperature. Steady-flow Reynolds numbers Re in the range of 200 and 600 were studied. The results of the CFD simulations show that, for the effect fin spacing to be significant on heat transfer enhancement in finned system with oscillating flow, the oscillating flow velocity must be higher than the mean flow velocity. Superposition of oscillation yields increasing heat transfer performance with increasing fin height. Fin geometry with pyramidal shape yields highest performance in terms of the heat transfer effectiveness. IntroductionIn order to generate very complex transient interactions of eddies and flow deflection especially in the laminar flow regime, pulsation of flow through a duct containing series of transverse sharp edges can be used. According to Ni and Gough [1], the fluid mechanical conditions of this system were described to be complex, with similar magnitudes for both axial and radial velocity components. This has been found to yield significant influences on both heat and mass transfer. The fluid mechanical conditions for this kind of system were described to be governed by three main dimensionless groups, i.e. the oscillatory Reynolds number Re osc , the steady Reynolds number Re and the Strouhal number St [1][2][3][4][5][6][7]. The oscillatory Reynolds number describes the intensity of mixing applied to the system and the Strouhal number is the ratio of the system diameter to the stroke length (amplitude), which is a measure of the effective eddy propagation [6,7]. In [4][5][6], the dimensionless amplitude, which is the ratio of the oscillation amplitude to the hydraulic diameter of their device, was used instead of the Strouhal number. In addition, non-dimensional geometric parameters were also considered in the dimensionless groups, for the description of fluid mechanical conditions of the system in [4][5][6].Several research efforts have been made to develop the basics for the increased transport in this system. In [6,[8][9][10][11], the effects of flow pulsation in a channel or duct containing sharp edges arranged in ducts on the heat transfer coefficient were considered. A numerical study of the laminar natural convection from a vertical plate with non-conducting baffles subjected to a periodic oscillation was performed in [10]. Local heat transfer measurements for oscillatory flow in a channel with a single conducting baffle was considered in [11]. A numerical study of the effects of a horizontal baffle on the heat transfer characteristics of pulsating mixed convection in a parallel vertical open channel was studied in [9]. The heat transfer performance of a periodically baffled tube subjected to oscillatory flow was investigated experimentally in [2,3,8]. The baffles were conducting and rectangular in shape. The influence of serie...

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Flow pulsation and baffle’s effects on the opposing mixed convection in a vertical channel

Cited by 25 publications

References 33 publications

Effect of viscous dissipation on mixed convection flow in a vertical double passage channel using Robin boundary conditions

Effect of viscous dissipation on mixed convection flow in a vertical double passage channel using Robin boundary conditions

Effects of Flow Pulsation on Forced Convection in a Channel Containing Regularly Spaced Nonconducting Fins

CFD Study of Effects of Module Geometry on Forced Convection in a Channel with Non‐Conducting Fins and Flow Pulsation

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