Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Gnanasekaran, G.Subject: search.filters.subject.Air preheaters

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    Numerical Study for Enhancement of Heat Transfer Using Discrete Metal Foam with Varying Thickness and Porosity in Solar Air Heater by LTNE Method
    (MDPI, 2022) Diganjit, R.; Gnanasekaran, G.; Mobedi, M.
    A two-dimensional rectangular domain is considered with a discrete arrangement at equal distances from copper metal foam in a solar air heater (SAH). The local thermal non-equilibrium model is used for the analysis of heat transfer in a single-pass rectangular channel of SAH for different mass flow rates ranging from 0.03 to 0.05 kg/s at 850 W/m2 heat flux. Three different pores per inch (PPI) and porosities of copper metal foam with three different discrete thicknesses at equal distances are studied numerically. This paper evaluates the performance of SAH with 10 PPI 0.8769 porosity, 20 PPI 0.8567 porosity, and 30 PPI 0.92 porosity at 22 mm, 44 mm, and 88 mm thicknesses. The Nusselt number for 22 mm, 44 mm, and 88 mm thicknesses is 157.64%, 183.31%, and 218.60%, respectively, higher than the empty channel. The performance factor for 22 mm thick metal foam is 5.02% and 16.61% higher than for 44 mm and 88 mm thick metal foam, respectively. Hence, it is found that metal foam can be an excellent option for heat transfer enhancement in SAH, if it is designed properly. © 2022 by the authors.
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    Analytical investigation on thermo hydraulic performance augmentation of triangular duct solar air heater integrated with wavy fins
    (Taylor and Francis Ltd., 2023) Renald, T.R.; P, S.; Matheswaran, M.; Gnanasekaran, G.
    Present work deals with performance improvement of triangular duct solar air heater by integration of wavy fin on absorber plate. An analytical model has been developed for the investigation of design parameters such as fin pitch ratio with ranges 0.05–0.2 and fin amplitude ratio with ranges 0.025–0.125. MATLAB code is generated to solve the energy balance equations by iterative procedure. The influence of design parameters on effective thermal and thermal efficiency is presented and its influences are discussed. Increasing the fin pitch ratio decreases the thermal and thermo hydraulic efficiency drastically. The positive effect of fin amplitude ratio is observed; increasing of fin amplitude ratio improves the thermal efficiency and effective efficiency up to the critical Reynolds number. The peak thermal efficiency of 85% is observed and thermo hydraulic efficiency of 80.16% is found at fin pitch ratio of 0.05 and fin amplitude ratio of 0.125. The maximum thermo hydraulic performance enhancement is 15.7% as it compared simple conventional solar triangular duct air extractors. The design plots are developed to select the performance parameters to attain required temperature rise values. © 2022 Taylor & Francis Group, LLC.