scholarly journals Review on Heat Transfer Enhancement by Louvered Fin

2021 ◽  
Vol 6 (1) ◽  
pp. 60-80
Author(s):  
Samsul Islam ◽  
Md. Shariful Islam ◽  
Mohammad Zoynal Abedin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Vortex Generator ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Louvered Fin ◽  
Heat Transfer Improvement ◽  
Better Than

The heat transfer enhancement is recycled in many engineering uses such as heat exchangers, refrigeration and air conditioning structures, chemical apparatuses, and automobile radiators. Hence many enhancing extended fin patterns are developed and used. In multi louvered fin, in this segment for multi-row fin and tube heat exchanger, an increase in heat transfer enhancement is found 58% for ReH = 350. When the Reynolds number is 1075, the temperature gradient is more distinct for greater louver angle that is the higher heat transfer enhanced for large louver angle. For variable louver angle heat exchanger, the maximum heat transfer improvement achieved by 118% Reynolds number at 1075. In the vortex generator for the delta winglet vortex generator, the extreme enhancement of heat transfer increased to 16% compared to the baseline geometry (at ReDh = 600). For a compact louvered heat exchanger, the results showed that a regular arrangement of louvered fins gives a 9.3% heat transfer improvement. In multi-region louver fins and flat tubes heat exchanger, the louver fin with 4 regions and the louver fin with 6 regions are far better than the conventional fin in overall performance. At the same time, the louver fin with 6 regions is also better than the louver fin with 4-region. The available work is in experimental form as well as numerical form performed by computational fluid dynamics.

Numerical Investigation of Heat Transfer Enhancement Using Hybrid Vortex Generator Arrays in Fin-and-Tube Heat Exchangers

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Shubham Agarwal ◽  
R. P. Sharma
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Vortex Generator ◽  
Roll Angle ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Hybrid Configuration

This is a novel study for assessing the heat transfer enhancement in a multi-row inline-tube heat exchanger using hybrid vortex generator (VG) arrays, i.e., rectangular winglet pairs (RWPs) with different geometrical configurations installed in coherence for enhanced heat transfer. The three-dimensional numerical study uses a full scale seven-tube inline heat exchanger model. The effect of roll of rectangular winglet VG on heat transfer enhancement is analyzed and optimized roll angle is determined for maximum heat transfer enhancement. Four different configurations are analyzed and compared in this regard: (a) single RWP (no roll); (b) 3RWP-inline array(alternating tube row with no roll of VGs); (c) single RWP (with optimized roll angle VGs); and (d) 3RWP-inline array(alternating tube row with all VGs having optimized roll angle). It was found that the inward roll of VGs increased the heat transfer from the immediately downstream tube but reduced heat transfer enhancement capability of other VG pairs downstream. Further, four different hybrid configurations of VGs were analyzed and the optimum configuration was obtained. For the optimized hybrid configuration at Re = 670, RWP with optimized roll angle increased heat transfer by 17.5% from the tube it was installed on and by 42% from the immediately downstream tube. Increase in j/ƒ of 36.7% is obtained by use of hybrid VGs in the optimized hybrid configuration. The deductions from the current study are supposed to well enhance the performance of heat exchangers with different design configurations.

Air-Side Heat Transfer Enhancement by a Novel Winglet-Type Vortex Generator Array in a Round-Tube Plain-Fin Heat Exchanger

2009 ◽  
Author(s):  
Jing He ◽  
Liping Liu ◽  
Anthony M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Vortex Generator ◽  
Attack Angle ◽  
Transfer Enhancement ◽  
Number Range ◽  
Reynolds Number Range ◽  
Goodness Factor

The impact of vortex generator (VG) arrays for air-side heat transfer enhancement is experimentally investigated by full-scale wind-tunnel testing of a plain-fin-and-tube heat exchanger. The VG array is deployed in a “V” to try to create a constructive interference between vortices. Each array is composed of two delta-winglet pairs (four VGs), and placed at an attack angle of 10° or 30°. The frontal air velocity considered is between 2.3–5.4 m/s, corresponding to a Reynolds number range based on the hydraulic diameter of 1500–3400. The thermal-hydraulic performance of the heat exchanger with and without VG enhancement is provided under dry-surface conditions. The experimental results indicate little impact at a relatively small attack angle of 10°. While for the 30° array, a 25–55% augmentation in air-side heat transfer coefficient is measured, but with a pressure drop penalty of 100%. Nevertheless, performance evaluation using the area goodness factor and the volume goodness factor both indicate the superiority of the enhanced heat exchanger by the 30° array over the entire Reynolds number range. The proposed array is found more effective at comparatively low Reynolds numbers, representative of many HVAC&R applications and compact heat exchanger designs.

An Experimental Investigation of Heat Transfer Enhancement by Pulsating Laminar Flow in a Triangular Grooved Channel

2012 ◽  
Vol 516-517 ◽  
pp. 249-252 ◽  
Author(s):  
Bing Chang Yang ◽  
Dong Xu Jin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Strouhal Number ◽  
Enhancement Factor ◽  
Pulsating Flow ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Pulsation Amplitude ◽  
Maximum Heat Transfer

Heat transfer enhancement by pulsating flow in a triangular grooved channel has been experimentally investigated. Effects of Reynolds number Re, Strouhal number St, pulsation amplitude A on the heat transfer enhancement were studied. The experimental results show that, the pulsating flow can significantly enhance heat transfer compared to the steady flow case, for instance, an enhancement of 115% is achieved at Re=400, A=0.5 and St=0.3. There exists an optimal Strouhal number corresponding to the maximum heat transfer enhancement factor. The heat transfer enhancement factor increases with the increase of Reynolds number and pulsation amplitude.

Experimental Study on Heat Transfer Performances of Flat Tube Bank Fin Heat Exchanger Using Four Different Fin Patterns

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Feng-Cai Zheng ◽  
Song Liu ◽  
Zhi-Min Lin ◽  
Jaafar Nugud ◽  
Liang-Chen Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchangers ◽  
Transfer Enhancement ◽  
Tube Bank ◽  
Number Range ◽  
Flat Tube ◽  
Louvered Fin ◽  
Delta Winglet ◽  
Better Than

Air-side heat transfer and flow friction characteristics of four different fin patterns suitable for flat tube bank fin heat exchangers are investigated experimentally. The fin patterns are the fin with six dimples, the fin with nine dimples, the double louvered fin, and the fin with delta-winglet vortex generators (VGs). The corresponding plain fins (plain fin I and plain fin II) are used as the references for evaluating the thermal performances of these fin patterns under identical pump power constraint. The performance of the fin with the six dimples is better than that with nine dimples. The performance of the fin with delta-winglet VGs is better than that of the double louvered fin, and the performance of the latter is better than that of the fins with six or nine dimples. In the tested Reynolds number range, the heat transfer enhancement performance factor of the fin with six dimples, the fin with nine dimples, the double louvered fin, and the fin with delta-winglet VGs is 1.2–1.3, 1.1–1.2, 1.3–1.6, and 1.4–1.6, respectively. The correlations of Nusselt number and friction factor with Reynolds number for the fins with six/nine dimples and the double louvered fin are obtained. These correlations are useful to design flat tube bank fin heat exchangers.

Heat Transfer Enhancement in Channel Flow Using an Inclined Square Cylinder

2008 ◽  
Author(s):  
Dong-Hyeog Yoon ◽  
Kyung-Soo Yang ◽  
Choon-Bum Choi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Large Scale ◽  
Vortex Generator ◽  
Square Cylinder ◽  
Transfer Enhancement ◽  
Enhance Heat Transfer ◽  
Positive Role ◽  
Secondary Vortices

The large-scale vortices shed from a cylindrical object as a vortex generator can be used to enhance heat transfer in a heat exchanger [1]. Furthermore, the large-scale vortices induce secondary vortices on the walls of a heat exchanger, which also play a positive role in heat transfer enhancement.

Endwall Heat Transfer Enhancement Around Cylinders With a Wall-Mounted Vortex Generator Pair

2017 ◽  
Author(s):  
Safeer Hussain ◽  
Jian Liu ◽  
Lei Wang ◽  
Bengt Sundén
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Vortex Generator ◽  
Diameter Ratio ◽  
Upstream Region ◽  
Spanwise Direction ◽  
Transfer Enhancement ◽  
Nusselt Numbers

Measurement of endwall heat transfer around a circular cylinder with a vortex generator pair has been investigated. Steady state liquid crystal thermography is adopted. Cylinders having two different height to diameter ratios have been employed. In one case, the cylinder has one end free in the flow and in the other case it has both ends attached on the walls. Local Nusselt numbers both upstream and downstream of the cylinder with and without the vortex generator pair are calculated. Nusselt numbers in streamwise and spanwise directions for both cases with vortex generator are compared with each other as well as with corresponding base cases. It is found from the experiments that the vortex generator influences the endwall heat transfer significantly downstream of the cylinder but has a small effect in the upstream region. Moreover, for different height to diameter ratio of the cylinder different heat transfer patterns are observed downstream of the cylinder. The vortex generator pair plays its major role on the endwall heat transfer enhancement in the spanwise direction and it expands as one moves from the upstream to downstream direction. To fully understand the advantage of the vortex generator pair, thermal performance is calculated for each case and it was found that in presence of the vortex generator pair, the cylinder with shorter height to diameter ratio shows higher thermal performance. Reynolds number dependence has also been investigated and it was found that the thermal performance decreases with increasing Reynolds number for both cases having a vortex generator pair.

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