CFD based performance analysis of a solar air heater duct provided with artificial roughness

Abstract. This paper aims to analyze uid ow characteristics and heat transfer augmentation in the air duct of a solar air heater using CFD techniques. The air duct has a rectangular section, the top wall is the glazing and the bottom one is the absorber provided with transverse rectangular or squared ribs. The simulations are performed in the turbulent regime and RANS formulation is used to model the ow and resolve mass, momentum, and energy equations using Finite Volumes method. The air ow analysis shows that the velocity pro le is not disturbed by the ribs outside the laminar sublayer. Heat transfer analysis based on the calculation of Nusselt Number, friction factor, and thermo-hydraulic performance highlights the heat transfer enhancement and no big friction losses are recorded. A comparative study between two rib shapes (square and rectangular) is performed, which shows better thermohydraulic performance of the rectangular ribs.

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“…In Figure 18, we plot the global thermohydraulic performance parameter curve presented by many authors [19,20,26]:…”

Section: Heat Transfer Analysismentioning

confidence: 99%

“…Studies using CFD techniques were fewer in the last decade [19,20], but their number is in constant growth because of the computer technology development and several numerical codes available [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of the Effect of Two Type of Ribs on Thermal Performance of Solar Air Heaters

2017

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“…These equations for incompressible streams can be written as follows. [24][25][26][27][28][29][30] :…”

Section: Governing Equationsmentioning

confidence: 99%

“…A critical review of literatures on rib roughened air duct reveals that very few studies are used CFD. 6,[24][25][26][27][28][29][30] To the best of our knowledge, no such type of CFD study has been reported on an artificially roughened air duct with V-shaped ribs combined with dimple ribs. The purpose of this work was to investigate fluid flow and heat transfer characteristics of a three-dimensional rectangular duct of an air duct with V with dimpled ribs by adopting the CFD approach.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on overall thermal performance in SAH duct with compound roughness of V-shaped ribs and dimples

Kumar¹,

Kim²

2015

Journal of the Korean Solar Energy Society

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: This paper presents the thermal hydraulic performance of a three dimensional rib-roughened solar air heater (SAH) duct with the one principal wall subjected to uniform heat flux. The SAH duct has aspect ratio of 12.0 and the Reynolds number ranges from 2000 to 12000. The roughness has relative rib height of 0.045, ratio of dimple depth to print diameter of 0.5 and rib pitch ratio of 8.0. The flow attack angle is varied from 35°to 70°. Various turbulent flow models are used for the heat transfer and fluid flow analysis and their results are compared with the experimental results for smooth surfaces. The computational fluid dynamics (CFD) results based on the renormalization k-epsilon model are in better outcomes compared with the experimental data. This model is used to calculate heat transfer and fluid flow in SAH duct with the compound roughness of V-shaped ribs and dimples. The overall thermal performance based on equal pumping power is found to be the highest (2.18) for flow attack angle of 55°. The thermo-hydraulic performance for V-pattern shaped ribs combined with dimple ribs is higher than that for dimple rib shape and V-pattern rib shape air duct.

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“…Some recent CFD studies [20][21][22][23][24][25][26][27][28][29][30] have also reported the enhancement in the thermal performance of solar air heaters by testing roughness geometries similar to those being employed for experimental investigations by many researchers in the past. These findings authenticate the usefulness of the experimental studies for the analysis of heat transfer and fluid flow behaviour of the artificially roughened SAHs.…”

Section: Introductionmentioning

confidence: 99%

CFD Analysis on the Thermal Hydraulic Performance of an SAH Duct with Multi V-Shape Roughened Ribs

Kumar

Kim

2016

Energies

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This study presents the heat transfer and fluid flow characteristics in a rib-roughened SAH (solar air heater) channel. The artificial roughness of the rectangular channel was in the form of a thin circular wire in discrete multi V-pattern rib geometries. The effect of this geometry on heat transfer, fluid flow, and performance augmentation was investigated using the CFD (computational fluid dynamics). The roughness parameters were a relative discrete distance of 0.69, a relative rib height of 0.043, a relative rib pitch of 10, a relative rib width of 6.0, and a flow-attack-angle of 60˝. The discrete width ratios and Reynolds numbers ranged from 0.5 to 2.0 and from 2000 to 20,000, respectively. The CFD results using the renormalization k-epsilon model were in good agreement with the empirical relationship. This model was used to investigate the heat transfer and fluid flow characteristics in the multi V-pattern rib roughened SAH channel. The thermo-hydraulic performance was found to be the best for the discrete width ratio of 1.0. A discrete multi V-pattern rib combined with dimple staggered ribs also had better overall thermal performance compared to other rib shapes.

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CFD based performance analysis of a solar air heater duct provided with artificial roughness

Cited by 199 publications

References 24 publications

Comparative Study of the Effect of Two Type of Ribs on Thermal Performance of Solar Air Heaters

Comparative Study of the Effect of Two Type of Ribs on Thermal Performance of Solar Air Heaters

Numerical study on overall thermal performance in SAH duct with compound roughness of V-shaped ribs and dimples

CFD Analysis on the Thermal Hydraulic Performance of an SAH Duct with Multi V-Shape Roughened Ribs

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