scholarly journals Compound Heat Transfer Enhancement of Wavy Fin-and-Tube Heat Exchangers through Boundary Layer Restarting and Swirled Flow

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1959 ◽  
Author(s):  
Ali Sadeghianjahromi ◽  
Saeid Kheradmand ◽  
Hossain Nemati ◽  
Jane-Sunn Liaw ◽  
Chi-Chuan Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Transfer Enhancement ◽  
Flat Portion ◽  
Improve Heat Transfer ◽  
Swirled Flow

This study performs a 3D turbulent flow numerical simulation to improve heat transfer characteristics of wavy finandtube heat exchangers. A compound design encompassing louver, flat, and vortex generator onto wavy fins can significantly enhance the heat transfer performance of wavy fin-and-tube heat exchangers. Replacement of wavy fins around tubes with flat fins is not effective as far as the reduction of thermal resistance is concerned, although an appreciable pressure drop reduction can be achieved. Adding two louvers with a width of 8 mm to the flat portion can reduce thermal resistance up to 6% in comparison with the reference wavy fin. Increasing the louver number and width can further decrease the thermal resistance. Also, it is found that the optimum louver angle is equal to the wavy angle for offering the lowest thermal resistance. Therefore, compound geometry with three louvers, a width of 12 mm, and the louver angle being equal to wavy angle with waffle height to be the same as fin pitch of the reference wavy fin has the most reduction in thermal resistance of 16% for a pumping power of 0.001 W. Adding punching longitudinal vortex generators on this compound geometry can further decrease thermal resistance up to 18%.

scholarly journals Numerical investigation on heat transfer enhancement inside a rectangular microchannel with vortex generator using TiO2, Cuo-water nanofluids

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Arash Behaeen ◽  
Mohammad Nimafar
Keyword(s):  
Heat Transfer ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Transfer Enhancement ◽  
Rectangular Microchannel ◽  
Transfer Rates ◽  
Improve Heat Transfer ◽  
Transfer Properties

One of the innovative ways to improve heat transfer properties of heat exchangers, is using nanofluids instead of traditional fluids. Due to presence of metal and oxides of metal particles in nanofluids structure, they have better potential in different environments and conditions than conventional fluids and having higher thermal conductivity causes improvements in heat transfer properties. In this research flow of two different nanofluids through a rectangular microchannel consisting of different number of longitudinal vortex generators (lvgs), has been investigated. Simulations conducted under laminar flow boundary condition and for different Reynolds numbers from 100 to 250. Considered volumetric concentration in this paper is 1, 1/6 and 2/3 %. Results showed, nanofluids and the LVGs remarkably enhance the heat transfer rates inside the microchannel. havg improved with increasing the nanoparticles volume concentrations and Reynolds number, whereas the opposite trends observed for pressure drop. havg improved for 4 to 12 and 9 to 18% for TiO2 and CuO nanofluids, respectively for different volume concentrations in simple microchannel. For lvg-enhanced microchannel the amount of improvements is about 9-14 and 5-10% for CuO and TiO2, respectively. Also using vortex generators alone improved havg for 15-25% for different number of lvgs.

An Efficient Approach for Performance Evaluation and Parameter Design of Heat Transfer Enhancing Structure

2010 ◽  
Author(s):  
Wen-Jing Zhou ◽  
Ju-Fang Fan ◽  
Zhi-Geng Wu ◽  
Ya-Ling He ◽  
Wen-Quan Tao
Keyword(s):  
Heat Transfer ◽  
Taguchi Method ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Parameter Design ◽  
Geometrical Parameters ◽  
Heat Transfer Area ◽  
Pumping Power ◽  
Transfer Enhancement

The effects of main geometrical parameters of the longitudinal vortex generator (LVG) called “common flow up” on heat transfer enhancement and pressure loss are numerically investigated. Taguchi method is used to guide the numerical simulations. Based on the results of the Taguchi method, a new fin with the combination of different vortex generators is proposed to substitute the original wavy fin-and-tube surface. The results show that the new fin with LVGs can save 9.08% of pumping power while reaching the same amount of heat transfer rate as the wavy fin at inlet velocity of 2m/s, and it can also save 33% of heat transfer area.

A Comparative Study of Fin-and-Tube Heat Exchangers With Various Fin Patterns

2008 ◽  
Author(s):  
L. H. Tang ◽  
G. N. Xie ◽  
M. Zeng ◽  
M. Lin ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Delta Wing ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Algorithm Optimization ◽  
Different Types ◽  
High Reynolds

Air-side heat transfer and friction characteristics of five kinds of fin-and-tube heat exchangers, with the number of tube rows (N = 12) and the diameter of tubes (Do = 18 mm), have been experimentally investigated. The test samples consist of five types of fin configurations: Crimped spiral fin, plain fin, slit fin, fin with delta-wing longitudinal vortex generators and mixed fin with front 6-row vortex-generator fin and rear 6-row slit fin. The heat transfer and friction factor correlations for different types of heat exchangers are obtained with the Reynolds numbers ranging from 4000 to 10000. It is found that crimped spiral fin provides higher heat transfer and pressure drop than the other four fins. The air-side performance of heat exchangers with crimped spiral fin, plain fin, slit fin, fin with delta-wing longitudinal vortex generators and mixed fin with front 6-row vortex-generator fin / rear 6-row slit fin has been evaluated under four sets of criteria and it is shown that the heat exchanger with mixed fin (front vortex-generator fin and rear slit fin) has better performance than that with fin with delta-wing vortex generators, and the slit fin offers best heat transfer performance at high Reynolds numbers. Based on Genetic Algorithm optimization results it is indicated that the increase of length and decrease of height may enhance the performance of vortex generator fin.

Heat transfer enhancement in fin-plate heat exchangers by wing type vortex generators

1989 ◽  
Vol 12 (1) ◽  
pp. 288-294 ◽  
Author(s):  
Udo Brockmeier ◽  
Martin Fiebig ◽  
Thomas Güntermann ◽  
Nimai K. Mitra
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Plate Heat
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