Using Patterned Surface Wettability to Enhance Air-Side Heat Transfer Through Frozen Water Droplet Vortex Generators – Part II: CFD Simulation Results

2021 ◽  
Author(s):  
Andrew E. Koopman ◽  
Andrew D. Sommers ◽  
Christian J.L. Hermes
Keyword(s):  
Heat Transfer ◽  
Water Droplet ◽  
Cfd Simulation ◽  
Vortex Generators ◽  
Surface Wettability ◽  
Patterned Surface ◽  
Simulation Results

Optimization of the Angle of Attack of Delta-Winglet Vortex Generators Over a Bank of Elliptical-Tubes Heat Exchanger

2013 ◽  
Author(s):  
K. Godazandeh ◽  
M. H. Ansari ◽  
B. Godazandeh ◽  
M. Ashjaee
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Cfd Simulation ◽  
Angle Of Attack ◽  
Vortex Generators ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Transfer Enhancement ◽  
The Impact

In order to reach a more efficient and compact heat exchanger, it is essential to optimize the design, having in mind the impact of different geometrical parameters. Many of the previously cited studies in the area of heat transfer enhancement using vortex generators were confined only to defined points in the possible design space. Thus, a multi-objective optimization study is particularly suitable in order to cover this space entirely. A CFD simulation along with Pareto method were used to simulate the air flow and heat transfer and optimize the design parameters. The angle of attack of a pair of delta-winglets mounted behind each tube is varied between β = −90° and β = +90°. Three elliptical tube rows with inline arrangements are investigated for Reynolds numbers from 500 to 1500 (based on the inlet properties). Use of delta-winglets as heat transfer enhancement elements increases the performance of elliptical-tubes heat exchanger. This enhancement is mainly due to the fact that delta-winglets increase the level of vorticity inside these devices and thus the mixing of the fluid is enhanced.

scholarly journals Numerical Analysis on Thermohydraulic Performance of the Tube Inserted with Rectangular Winglet Vortex Generators

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 179
Author(s):  
Yicong Li ◽  
Zuoqin Qian ◽  
Qiang Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Circular Tube ◽  
Vortex Generators ◽  
Transfer Performance ◽  
Empirical Formulas ◽  
Influence Mechanism ◽  
Simulation Results ◽  
The Impact

The aim of this design was to improve the heat transfer performance significantly due to larger turbulent region and much vortices formed by tube inserted. In this article, the BSL k-ω model was chosen as turbulence model to simulate the thermohydraulic performance of the proposed tubes inserted with rectangular winglet vortex generators (RWVGs) when the Re was set as 5000 to 15,000. The reliability of the simulation results was obtained by comparing with the empirical formulas and experimental results. By means of numerical simulation, the influence mechanism of geometric parameters of RWVGs on thermal-hydraulic performance in tubes was analyzed. And the impact of three configurational parameters on the thermal performance was studied, namely the angle α, the height H and the number N of the RWVGs, respectively. The results revealed that the capacity of heat transfer in tubes with RWVG inserts was obviously larger than that in ordinary circular tube. In addition, it could be seen from the results that both Nu and f increased with the increase of H and N. At the same time, the case of α = 135° showed the greatest enhancement of thermal performance than the case of α = 45° and α = 90°.The PEC achieved the highest value of 1.23 when the height H of RWVG was 0.7 mm, the number N was 20, and angle α was 135°.

New correlations for wavy plate-fin heat exchangers: different working fluids

2014 ◽  
Vol 24 (5) ◽  
pp. 1086-1108 ◽  
Author(s):  
Morteza Khoshvaght Aliabadi ◽  
Faramarz Hormozi ◽  
Elham Hosseini Rad
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Cfd Simulation ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Working Fluids ◽  
Content Type ◽  
Simulation Results

Purpose – The main purpose of this paper is the generation of the heat transfer and pressure drop correlations by considering three working fluids, namely air, water, and ethylene glycol, for the wavy plate-fin heat exchangers (PFHEs). Design/methodology/approach – In order to present the general correlations, various models with different geometrical parameters should be tested. Because of the problems, such as difficult, long time, and costly fabrication of the wavy fins in experimental tests, computational fluid dynamics (CFD) calculations can be a useful method for the generation of the heat transfer and pressure drop correlations with eliminating the experimental problems. Hence, the effective design parameters of the wavy plate-fin, including fin pitch, fin height, wave length, fin thickness, wave amplitude, and fin length, and also their levels were recognized from the literature. The Taguchi method was applied to formulate the CFD simulation work. Findings – The simulation results were compared and validated with an available experimental data. The mean deviations of the Colburn factor, j, and Fanning friction factor, f, values between the simulation results and the experimental data were 3.74 and 9.07 percent, respectively. The presented air correlations and experimental data were in a good agreement, so that approximately 95 percent of the experimental data were correlated within ±12 percent. The j factor values varied for the different working fluids, while the f factor values did not sensibly change. Practical implications – The presented correlations can be used to estimate the thermal-hydraulic characteristics and to design of the compact PFHE with the wavy channels. Originality/value – This manuscript presents the new correlations for the compact PFHEs with the way channels by considering all the geometrical parameters and the working fluids with the different Prandtl numbers, 0.7, 7, and 150.

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