An Analysis of a Duct with Different Vortex Generators for Performance Enhancement of a Solar Air Heater: Computational Fluid Dynamics (CFD)

Offset strip fins (OSF) have been widely used in plate-fin heat exchangers. Conventional OSFs are constructed with plain fins. Various design modifications to improve the performance of OSFs are compared here. The modifications suggested include perforations, dimples, vortex generators, and a double-layer design. The performance capabilities are evaluated using a computational fluid dynamics (CFD) analysis. The performances are compared in terms of the j-factor, f-factor, area goodness factor, and volume goodness factor. The f-factors of all modified designs appeared to be higher than that of the plain OSF, while the j-factor was found to be higher or lower than that of the plain OSF depending on the design modification used. The plain OSF has the largest area goodness factor, while OSFs with multiple perforations and dimples show a higher volume goodness factor than the plain OSF.

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Performance Investigation of a Triangular Solar Air Heater Duct Having Broken Inclined Roughness Using Computational Fluid Dynamics

Journal of Solar Energy Engineering ◽

10.1115/1.4043751 ◽

2019 ◽

Vol 141 (6) ◽

Cited By ~ 8

Author(s):

Sheetal Kumar Jain ◽

Ghanshyam Das Agrawal ◽

Rohit Misra ◽

Prateek Verma ◽

Sanjay Rathore ◽

...

Keyword(s):

Heat Transfer ◽

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Large Scale ◽

Rectangular Cross Section ◽

Heated Surface ◽

Clean Energy ◽

Solar Air Heater ◽

Air Heater ◽

Gap Width

Large-scale adaptation of solar air heating in industries and agro-processing will lead to clean energy processing as well as reducing the production cost for these industries. The solar air heater uses the principle of the greenhouse effect to heat air through the collected heat in the absorber. Among the various techniques employed by the researchers to augment heat transfer, the addition of artificial roughness elements/fins/corrugations on the heated surface is the promising one for heat transfer augmentation. In the present work, the effect of broken inclined ribs with rectangular cross-section on heat transfer and friction characteristics of the equilateral triangular passage duct has been analyzed using computational fluid dynamics. The effect of roughness parameters, viz., relative gap position and relative gap width, is being investigated for the Reynolds number (Re) ranging from 4000 to 18,000. The values of relative gap position (d/W) and relative gap width (g/e) are varied from 0.16 to 0.67 and 0.5 to 2, respectively, while a constant heat flux is supplied on the absorber side, other surfaces being insulated. The Nusselt number increased up to 2.16 times by using broken ribs than that of the smooth duct at d/W = 0.25 and g/e = 1.

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A CFD (Computational Fluid Dynamics) Based Thermal Performance of Solar Air Heater With Rib-Roughened Channels

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2016-66375 ◽

2016 ◽

Author(s):

Mumtaz Hussain Qureshi ◽

M. Shakaib

Keyword(s):

Heat Transfer ◽

Fluid Dynamics ◽

Heat Flux ◽

Computational Fluid Dynamics ◽

Research Work ◽

Solar Air Heater ◽

Transfer Coefficients ◽

Turbulent Fluid Flow ◽

Transfer Rates ◽

Air Heater

Computational Fluid Dynamics (CFD) study is conducted to determine turbulent fluid flow and temperature profiles in rectangular ribbed channels of solar air heater. The results show significant effect of Reynolds number and ribs height and pitch on turbulence and heat transfer rates. When heat flux is defined at the bottom wall, the temperature values increase rapidly near the ribs due to stagnant zones. The heat transfer coefficients are lower at these locations. When heat flux is specified at the top wall, the variation in heat transfer coefficient is relatively smooth. From the research work, the channel containing ribs of 3mm and pitch 40mm are determined suitable due to higher heat transfer rates.

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