scholarly journals A Numerical and Experimental Investigation of Dimple Effects on Heat Transfer Enhancement with Impinging Jets

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 813 ◽  
Author(s):  
Parkpoom Sriromreun ◽  
Paranee Sriromreun
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Transfer Enhancement ◽  
Air Flow ◽  
Flow Characteristics ◽  
Jet Impingement ◽  
Impinging Jets ◽  
Transfer Enhancement ◽  
Test Plate ◽  
Hot Surface

This research was aimed at studying the numerical and experimental characteristics of the air flow impinging on a dimpled surface. Heat transfer enhancement between a hot surface and the air is supposed to be obtained from a dimple effect. In the experiment, 15 types of test plate were investigated at different distances between the jet and test plate (B), dimple diameter (d) and dimple distance (Er and Eθ). The testing fluid was air presented in an impinging jet flowing at Re = 1500 to 14,600. A comparison of the heat transfer coefficient was performed between the jet impingement on the dimpled surface and the flat plate. The velocity vector and the temperature contour showed the different air flow characteristics from different test plates. The highest thermal enhancement factor (TEF) was observed under the conditions of B = 2 d, d = 1 cm, Er= 2 d, Eθ = 1.5 d and Re = 1500. This TEF was obtained from the dimpled surface and was 5.5 times higher than that observed in the flat plate.

scholarly journals Enhanced heat transfer characteristics of conjugated air jet impingement on a finned heat sink

2017 ◽  
Vol 21 (1 Part A) ◽  
pp. 279-288 ◽  
Author(s):  
Shuxia Qiu ◽  
Peng Xu ◽  
Liping Geng ◽  
Arun Mujumdar ◽  
Zhouting Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Flow Characteristics ◽  
Jet Impingement ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Air Jet

Air jet impingement is one of the effective cooling techniques employed in micro-electronic industry. To enhance the heat transfer performance, a cooling system with air jet impingement on a finned heat sink is evaluated via the computational fluid dynamics method. A two-dimensional confined slot air impinging on a finned flat plate is modeled. The numerical model is validated by comparison of the computed Nusselt number distribution on the impingement target with published experimental results. The flow characteristics and heat transfer performance of jet impingement on both of smooth and finned heat sinks are compared. It is observed that jet impingement over finned target plate improves the cooling performance significantly. A dimensionless heat transfer enhancement factor is introduced to quantify the effect of jet flow Reynolds number on the finned surface. The effect of rectangular fin dimensions on impingement heat transfer rate is discussed in order to optimize the cooling system. Also, the computed flow and thermal fields of the air impingement system are examined to explore the physical mechanisms for heat transfer enhancement.

Heat Transfer Enhancement With Inclined Baffles and Ribs Combined

2001 ◽  
Author(s):  
Jamil A. Khan ◽  
Jason Hinton ◽  
Sarah C. Baxter
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Enhancement ◽  
Heated Surface ◽  
Rectangular Channel ◽  
Jet Impingement ◽  
Impinging Jets ◽  
Transfer Enhancement ◽  
Enhance Heat Transfer ◽  
Rib Turbulators

Abstract Common heat transfer enhancement techniques are found in many of today’s processes. Devices such as inclined baffles, rib turbulators, jet impingement, etc are all used in order to augment the thermal transfer of a process. Inclined baffles have been studied along with the combination of jet impingement techniques. Inclined baffles enhance heat transfer by enhancing large-scale fluid bulk motion and through tripped boundary layer flow separation. Impinging jets, created by perforating the baffle, create additional heat transfer through flow impingement on the heated surface. Rib turbulators create heat transfer augmentation by disturbing the thermal boundary layer, unlike baffles; ribs enhance heat transfer in areas near the heat transfer surface leaving the core flow largely undisturbed. This investigation investigates experimental heat transfer of turbulent flow in a rectangular channel with inclined solid and perforated baffles combined with rib turbulators for isoflux heating at the top surface of the channel. Combining ribs with baffles yielded an increase in average Nusselt Number, albeit, with a pressure drop penalty. In situations where rate of heat transfer is critical to the performance of a device combining ribs with baffle is a viable solution.

Jet Impingement Heat Transfer Enhancement on a rib-roughened Flat Plate

2016 ◽  
Author(s):  
A H. Alenezi ◽  
Joao Amaral Teixeira ◽  
Abdulmajid Addali A. ◽  
Abdelaziz Gamil A. A. ◽  
Hamad M. Alhajeri
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Transfer Enhancement ◽  
Jet Impingement ◽  
Transfer Enhancement ◽  
Impingement Heat Transfer ◽  
Rib Roughened
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