Thermal Performance Analysis of an Artificially Roughened Solar Airborne Heater with Ribs: A CFD Analysis
T.S.V. Vijay Murali1, I.V. Kumar2, M. Mohan Jagadeesh Kumar3

1T.S.V. Vijay Murali, M.Tech Student, Gayatri Vidya Parishad College of Engineering (A), (Andhra Pradesh), India.
2I.V. Kumar, M.Tech Student, Gayatri Vidya Parishad College of Engineering (A), (Andhra Pradesh), India.
3M. Mohan Jagadeesh Kumar, Associate Professor, Gayatri Vidya Parishad College of Engineering (A), (Andhra Pradesh), India.
Manuscript received on 22 April 2019 | Revised Manuscript received on 04 May 2019 | Manuscript Published on 17 May 2019 | PP: 33-38 | Volume-7 Issue-6S4 April 2019 | Retrieval Number: F10070476S419/2019©BEIESP
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Abstract: Heat transfer coefficients in solar airborne heaters have to be passively upgraded by building turbulence near its absorbent plate. Turbulence near the plate can be augmented by attaching synthetic ribs of different geometries to its surface. In this paper numerical investigations are carried out and results are presented by simulating flow through solar airborne heater as continuous flow into a rectangular shaped duct with artificially ribbed bottom most surface. Ribs of dissimilar cross-sections including triangular, semi-circular, rectangular and arc in shape are considered for the numerical analysis. Constant heat flux boundary condition is being used at the bottom most surface of the rectangular shaped duct. Heat transfer rates for flow through rectangular shaped duct with plane bottom most surface are compared with corresponding values with ribbed bottom most surface. Reynolds number (2300-20000), relative roughness pitch (6.67, 10, 13.33) and relative roughness altitude (0.055, 0.073, 0.11) are considered as parametric variables. Heat transfer rates are found to be increased for ribbed rectangular bottom most surface compared to plane rectangular surface. Arc shaped ribs are giving higher augmentation in heat transfer through duct compared to rectangular, triangular and semi-circular ribs. Arc shaped ribs with a relative roughness altitude of 0.055 and relative roughness pitch of 10 increasing Nusselt number by 1.66 times comparing with plane surface. Arc shaped ribs with same relative roughness pitch increases Nusselt number by 1.78 and 1.48 times with relative roughness altitude equal to 0.073 and 0.11 respectively.
Keywords: Absorber Plate, Heat Transfer Coefficient, Reynolds Number, Solar Airborne Heater.
Scope of the Article: Heat Transfer