Study the influence of concavity shapes on augmentation of heat‐transfer performance, pressure field, and fluid pattern in three‐dimensional pipe

Heat Transfer ◽  
2021 ◽  
Author(s):  
Ahmed Ramadhan Al‐Obaidi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Pressure Field ◽  
Three Dimensional ◽  
Transfer Performance ◽  
Performance Pressure

Heat Transfer Enhancement for Wake Zone Using Slit Pillar in Microchannel Heat Sinks

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Xiao Cheng ◽  
Huiying Wu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Electronic Device ◽  
Three Dimensional ◽  
Lower Surface ◽  
Heat Sinks ◽  
Transfer Performance ◽  
Microchannel Heat Sinks ◽  
Dimensional Simulation ◽  
Wake Zone

Abstract Pillar microchannel heat sinks have been widely used for chip cooling, while their overall heat transfer performance is restricted by the stagnation flow in pillar wake zone. In this work, a simple but effective method using slit microstructure modified on pillar was proposed to enhance wake zone heat transfer. It enables a special flow path for the incoming fluid that intensively disturbs the wake fluid. To validate the proposed method, a three-dimensional simulation was employed to study the laminar flow and heat transfer characteristics in the slit pillar microchannel. The pillar without slit design was also investigated for comparative analysis. Effects of slit angle (θ), height over diameter ratio (H/D), and blocking ratio (D/W) of a single pillar were systematically studied at the Reynolds numbers of 26–260. Results showed the case with θ = 0 deg always demonstrated lower surface temperature, higher Nusselt number and higher thermal performance index (TPI) compared to other cases with different slit angles at the same conditions. Furthermore, it was interesting to find that the slit configuration was not suitable for long pillar microchannel, but preferred for high blocking ratio pillar microchannel at present ranges (H/D ≤ 1, D/W ≤ 0.5). The slit pillar array microchannel was also explored and observed with improved overall heat transfer performance. The proposed slit microstructure well prevents the heat transfer deterioration in pillar wake zone, which is promisingly to be used for cooling performance improvement of electronic device.

Enhanced Condensation Heat-Transfer on Mini or Low Fin Tubes

2006 ◽  
Author(s):  
Adrian Briggs
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermophysical Properties ◽  
Heat Transfer Performance ◽  
Three Dimensional ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Shell Side ◽  
Wide Range ◽  
Fin Tubes

This paper presents an overview of the use of low or mini-fin tubes for improving heat-transfer performance in shell-side condensers. The paper concentrates on, but is not limited to, the experimental and theoretical program in progress at Queen Mary, University of London. This work has so far resulted in an extensive data base of experimental data for condensation on single tubes, covering a wide range of tube geometries and fluid thermophysical properties and in the development of a simple to use model which predicts the majority of this data to within 20%. Work is progressing on the effects of vapor shear and on three-dimensional fin profiles; the later having shown the potential for even higher heat-transfer enhancement.

Numerical Investigation of a Crossflow Jet in a Rectangular Microchannel

2013 ◽  
Vol 284-287 ◽  
pp. 849-853
Author(s):  
Kok Cheong Wong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Three Dimensional ◽  
Horizontal Flow ◽  
Transfer Performance ◽  
Rectangular Microchannel ◽  
Transverse Jet ◽  
Nozzle Position ◽  
Jet Nozzle

The present numerical study is conducted in three dimensional to investigate the crossflow of an external round jet and a horizontal stream of microchannel flow. The results of heat transfer performance for the cases with and without transverse jet are compared. The patterns of different crossflow jet were analyzed to understand the flow and heat transfer characteristics. The effect of jet nozzle position on the heat transfer is investigated. Generally, the heat transfer performance increases with the jet Reynolds number. However, some cases of weak jet are found to cause lower heat transfer rate relative to the case without external jet. When vertical weak jet encounter strong horizontal flow, the horizontal flow is dominant that the jet cannot reach the microchannel bottom wall but imposes resistance to the horizontal flow. The investigation on the jet nozzle location shows that the jet nozzle location closer to the channel inlet gives better heat transfer performance.

scholarly journals Computational Study of Flow and Heat Transfer With Anti Cross-Flows (ACF) Jet Impingement Cooling for Different Heights of Corrugate

2017 ◽  
Author(s):  
Radheesh Dhanasegaran ◽  
Ssheshan Pugazhendhi
Keyword(s):  
Heat Transfer ◽  
Skin Friction ◽  
Heat Transfer Performance ◽  
Computational Study ◽  
Three Dimensional ◽  
Cross Flow ◽  
Transfer Performance ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Plate Spacing

In the present study, a flow visualization and heat transfer investigation is carried out computationally on a flat plate with 10×1 array of impinging jets from a corrugated plate. This corrugated structure is an Anti-Cross Flow (ACF) technique which is proved to nullify the negative effects of cross-flow thus enhancing the overall cooling performance. Governing equations are solved using k-ω Shear Stress Transport (SST) turbulence model in commercial code FLUENT. The parameter variation considered for the present study are (i) three different heights of ACF corrugate (C/D = 1, 2 & 3) and (ii) two different jet-to-target plate spacing (H/D = 1 & 2). The dependence of ACF structure performance on the corrugate height (C/D) and the flow structure has been discussed in detail, therefore choosing an optimum corrugate height and visualizing the three-dimensional flow phenomena are the main objectives of the present study. The three-dimensional flow separation and heat transfer characteristics are explained with the help of skin friction lines, upwash fountains, wall eddies, counter-rotating vortex pair (CRVP), and plots of Nusselt number. It is found that the heat transfer performance is high at larger corrugate heights for both the jet-to-plate spacing. Moreover, the deterioration of the skin friction pattern corresponding to the far downstream impingement zones is greatly reduced with ACF structure, retaining more uniform heat transfer pattern even at low H/D values where the crossflow effects are more dominant in case of the conventional cooling structure. In comparison of the overall heat transfer performance the difference between C/D = 3 & C/D = 2 for H/D = 2 is significantly less, thus making the later as the optimal configuration in terms of reduced channel height.

Heat Transfer and Entropy Generation Analysis of Slit Pillar Array in Microchannels

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Xiao Cheng ◽  
Huiying Wu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Entropy Generation ◽  
Heat Transfer Performance ◽  
Three Dimensional ◽  
Thermal Characteristics ◽  
Secondary Flows ◽  
Transfer Performance ◽  
Pillar Array

Abstract The slit pillar allows a small fraction of the mainstream flow through pillar to disturb the pillar wake zone fluid and eventually enhance the local and global heat transfer performances in microchannels. In this study, three-dimensional full-domain numerical simulations on the hydrodynamic and thermal characteristics of slit pillar array in microchannels are performed. Effects of slit angle and height over diameter (H/D) ratio on the fluid flow and heat transfer are studied. Comparisons with the nonslit pillar array are conducted on pressure drop, surface temperature, Nusselt number, and thermal performance index (TPI). Furthermore, the results are analyzed by using the entropy generation. As a result of secondary flows and enhanced convective heat transfer area, all cases at H/D ratio of 0.3 demonstrate enhanced heat transfer performance at an increase of 18.0–34.7% on Nusselt number, while a reduction of 3.4–12.9% on pressure drop in comparison to the criterion case at the same conditions. Among them, slit 15–15 deg shows the best comprehensive heat transfer performance. Due to the improved uniformities of velocity and temperature distributions, all slit pillar array microchannels show decreased entropy generation. The maximum entropy generation reduction can reach up to 15.8%, as compared with the criterion case at the same conditions. The above results fully demonstrate that the novel slit pillar array microchannel heat sink can be used as an effective approach for heat transfer enhancement.

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