Faculty Publications
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Item Exergy Analysis of a Triangular Duct Solar Air Heater with Square Ribs(Springer Science and Business Media Deutschland GmbH, 2022) Nidhul, K.; Kumar, S.; Yadav, A.K.; Anish, S.The awareness about limited energy resources has urged the scientific community to scrutinize the energy conversion devices and optimize existing limited resources. In this analytical study, the exergetic performance analysis of a triangular cross-section square ribbed solar air heater (SAH) is compared with a conventional SAH. Reynolds number (Re) and temperature rise parameter (∆T/G) are varied, and their effect on exergetic efficiency is quantified. For the present study, maximum exergetic efficiency for the present study is obtained for non-dimensionalized rib height (e/D) of 0.05 and non-dimensionalized rib pitch (P/e) of 10. The optimum combinations of roughness parameters are interpreted through plots to design turbulators for triangular cross-section solar air heaters. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Critical review of ribbed solar air heater and performance evaluation of various V-rib configuration(Elsevier Ltd, 2021) Nidhul, K.; Yadav, A.K.; Anish, S.; Kumar, S.The low heat transfer rate in a flat plate solar air heater (SAH) is due to the development of a laminar sub-layer near the heated absorber plate. Owing to this, the plate temperature rises substantially, instigating losses and thus reducing the efficiency. Extensive research has been carried out to mitigate this problem, of which passive technique emerged to be a promising solution. The passive method involves the application of fins/turbulators/ribs on the surface where the boundary layer develops so that it breaks the same. Various profiles and configurations of the ribs ranging from transverse to inclined and continuous to discrete have been presented concisely. Correlations on Nusselt number (Nu) and friction factor (f) for different rib configurations have been summarized in order so that it can be accessed for future research. 3-D CFD analysis is carried out to gain insight into the flow pattern of various V-ribbed SAH, and with the help of streamlines and contours, the findings are established. Furthermore, various exergy destruction has been studied in detail for different V-rib configurations, namely– V-rib, multiple V-rib, and multiple V-rib with the gap, and analyzed in detail for prospective studies. Exergetic performance study of these rib configurations indicates that the multiple ribs and the multiple rib-gap combinations enhance exergetic efficiency (ηex) by 12% and 31.6%, respectively, in comparison to V-rib SAH. © 2021 Elsevier LtdItem Machine learning approach for optimization and performance prediction of triangular duct solar air heater: A comprehensive review(Elsevier Ltd, 2023) Nidhul, K.; Thummar, D.; Yadav, A.K.; Anish, S.This paper presents a comprehensive review of various kinds of distinct artificial roughness employed in rectangular and triangular duct solar air heaters to aid prospective researchers in finding a critical gap in the domain of solar air heaters. A Machine Learning (ML) model is developed using 72 distinct rib combinations compiled to 454 datasets and trained using an Artificial Neural Network (ANN) to predict the performance of ribbed triangular duct Solar Air Heater (SAH). The developed ML model predicts the data with an average deviation of <3%. Owing to reasonably accurate predictions, the same could be increased when more cases (geometric or operating parameters) are added to the databases by retraining the ANN. Further, a second law analysis of the rib configurations features collector efficiency and entropy generation variation with Re for various rib parameters. For the Re range of 4000 to 18000, optimum parameters such as rib height, pitch, chamfer angle, and inclinations are obtained for triangular duct SAH. This could help design engineers obtain the performance parameters of ribbed triangular duct SAH with other artificial roughness designs, possibly with a combination of different geometrical and operating parameters, without having to perform tests. © 2023 International Solar Energy SocietyItem Thermo-hydraulic and exergetic performance of a cost-effective solar air heater: CFD and experimental study(Elsevier Ltd, 2022) Nidhul, K.; Yadav, A.K.; Anish, S.; Arunachala, U.C.An experimental and computational fluid dynamics (CFD) study is carried out to investigate the impact of secondary flow strengthening the thermo-hydraulic performance of discrete multiple inclined baffles in a flat plate solar air heater (SAH) with semi-cylindrical sidewalls. Initially, for a fixed relative baffle height (Rh = 0.1), the relative baffle pitch (Rp) for continuous baffles is varied in the range of 0.6–1 to obtain the optimum baffle pitch for 6000 p. A maximum thermo-hydraulic performance of 2.69 is obtained for the gap at the trailing apex. The proposed design has a higher collector efficiency, 55–70%, compared to the ribbed rectangular SAH design exhibiting 30–55%. With lower exergy losses, the present SAH design has higher exergetic efficiency (1.5%–2.2%)than ribbed rectangular SAH (0.9%–1.7%) for the range of Re studied. Further, at low Re, the present SAH design has a higher coefficient of performance, indicating that it is cost-effective than ribbed rectangular SAH designs. © 2021 Elsevier LtdItem Energy and exergy analysis of solar air heater with non-uniform porous medium under varying solar intensity and radiation effects: a 3-D CFD study(Taylor and Francis Ltd., 2025) Nidhul, K.; Joshi, A.; Yadav, A.K.; Anish, S.The effect of a thin porous layer on the performance of a solar air heater (SAH) is investigated for both uniform and non-uniform configurations. 3-D computational fluid dynamic (CFD) simulations of SAH are performed for turbulent flow, and the transient performance with porous medium configurations is studied. A discrete-ordinate (D-O) model is employed, and diurnal variations of solar heat flux and inlet air temperature variations are considered in this study. The porous medium above the absorber plate significantly enhances the SAH's thermo-hydraulic performance parameter (THPP). The proposed configuration reduces the irreversibility in heat transfer and the possible hot spots that could occur when ribs are employed as artificial roughness, thereby enhancing the Nusselt number (Nu). The highest increment in Nu is obtained as 7.5 times, leading to maximum enhancement in THPP by 60% for descending porous medium compared to uniform porous medium configuration. Further, from the exergy analysis, the descending porous medium reported higher collector efficiency (66-70%). Owing to higher exergy gain and lower exergy losses, the energetic efficiency of the descending porous configuration is higher than the uniform porous configuration. Both thermo-hydraulic and exergy performance increases due to conduction and radiation within the porous medium apart from convection. © 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.