Faculty Publications
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Publications by NITK Faculty
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Item Geometrical pole shape optimization of an outer rotor synchronous reluctance motor for output torque enhancement(Institute of Electrical and Electronics Engineers Inc., 2024) Chauhan, V.K.S.; Koorata, P.K.This article explores optimizing design for Permanent magnet (PM) free outer rotor synchronous reluctance machines to be used as in-wheel motors for electric vehicles. The primary objective is enhancing torque output by systematically analyzing various rotor pole shapes and parameters such as pole depth, arc angles, rib thickness, channel width, and fillet radii. These parameters were studied on four different types of pole shapes. Using ANSYS Maxwell software, the analysis is performed on an outer rotor motor with a diameter of 190 mm and a rated speed of 1200 RPM. The results indicate that outer rotor machines with configurations such as an inner arc angle of 9 degrees and an outer arc angle of 24 degrees exhibit optimal torque output for pole shape 1. Moreover, the study reveals that an increase in pole depth (SB) corresponds to an increase in torque output, while rib thickness reduces torque output. Additionally, the research explores the impact of fillet radii on torque performance. This study provides the effects of essential features of critical design parameters on reluctance torque for maximizing average torque in outer rotor motors utilized in EV applications. © 2024 IEEE.Item MULTIDIMENSIONAL INVESTIGATION OF THERMAL BEHAVIOR OF HIGH-POWER ELECTRIC VEHICLE MOTOR DURING ON-ROAD DRIVING CONDITIONS THROUGH ELECTROMAGNETIC, THERMAL, AND DRIVE CYCLE ANALYSIS(Begell House Inc., 2024) Chauhan, V.K.S.; Koorata, P.K.This study addresses the critical need to understand the thermal behavior of electric motors in real-world driving conditions, which is crucial for the global transition to electric vehicles (EVs) and for achieving sustainable energy goals. The real-world driving conditions include acceleration and deceleration, resulting in speed variations, and existing research often limits its scope to constant speed conditions, potentially providing misleading results. As existing research predominantly confines itself to constant speed conditions, our study fills this gap by investigating temperature variations during on-road driving scenarios, utilizing the SAE J227 drive cycle as a benchmark. Based on recent studies, we consider the design parameters of an appropriate EV motor and subject the developed model to thermal and fluid flow analyses. The impact of confinement on motor temperature rise is also explored for potential temperature reduction, contributing up to 4 percent temperature reduction. The drive cycle–based study indicated that running the motor at a constant speed yields a considerably lower temperature rise (ΔT < 74°C) than actual driving conditions. In contrast, temperatures in actual driving scenarios could exceed 136°C within similar durations. This study looks into the actual heating challenges faced by electric motors used in EVs by integrating analyses from electrical, thermal, and transportation engineering. © 2024 by Begell House, Inc. www.begellhouse.com.Item Synthesis, characterization of graft copolymers and their application in treatment of refinery wastewater(Springer, 2025) Chandan, K.K.; Chauhan, V.K.S.This article presents the synthesis, characterisation, and application of graft copolymers for coagulation-flocculation for cleaning refinery wastewater. The grafted copolymer is prepared using potassium persulfate as an initiator under a nitrogen atmosphere, and polysaccharides (Starch, amylose, and guar gum) as backbone polymers and acrylamide as the monomer. The synthesised grafted copolymer is characterised using standard techniques, and the molecular weight is estimated using the Mark-Houwink equation. The coagulation-flocculation experiments were conducted using alum as a coagulant and the synthesised graft copolymers as flocculants. The efficiency of turbidity removal was evaluated by adjusting the pH during synthesis and measuring the supernatant turbidity values. Results showed that the grafted copolymer St-g-PAM-II exhibited turbidity removal efficiency of 92.19% at pH 10. These findings demonstrate the potential of the grafted copolymer as an effective flocculant in refinery wastewater treatment. The synthesis process and characterisation techniques provided valuable insights into the structural and morphological properties of the graft copolymers. The estimated molecular weights provided approximate values for their molecular size. Present study highlighted the importance of pH adjustment and the role of graft copolymers in turbidity removal. This research contributes to developing sustainable and efficient wastewater treatment methods with potential applications in the petroleum industry. © Indian Academy of Sciences 2025.Item State-of-the-art assessment-based review of boiling heat transfer and friction factor correlations for NH3–H2O, NH3–LiNO3 and NH3–LiNO3–H2O mixtures in a plate heat exchanger(Nature Research, 2025) Chauhan, V.K.S.; Sathyabhama, A.; Hegde, R.N.The increasing demand for energy-efficient and environmentally sustainable cooling technologies has led to a renewed focus on ammonia and lithium nitrate-based absorption refrigeration systems, particularly those utilizing Plate Heat Exchangers (PHEs). Despite their importance, reliable predictive models for boiling heat transfer and frictional pressure drop in PHEs using ammonia and lithium nitrate mixtures, such as NH3–LiNO3 and NH3–LiNO3–H2O, remain limited and often suffer from structural deficiencies. This study provides a comprehensive evaluation of existing correlations for boiling heat transfer and friction factor in PHEs, specifically focusing on ammonia-based mixtures (NH3–H2O, NH3–LiNO3, and NH3–LiNO3–H2O). More than 20 correlations for boiling heat transfer coefficient and friction factor were critically analysed and adjusted to account for the unique thermophysical behaviors of multi-component salt mixtures. The study reveals that many correlations fail to accurately predict boiling heat transfer in NH3–H2O mixtures due to inadequate sensitivity to heat flux. Scaling these correlations led to notable improvements in prediction accuracy, underlining the significance of appropriate scaling for different PHE configurations. Additionally, the study validates the assumption that lithium nitrate remains in the liquid phase in NH3–LiNO3 and NH3–LiNO3–H2O mixtures, supporting its exclusion from latent heat calculations. Friction factor correlations that include positive exponents for Reynolds and Weber numbers were found to be structurally inconsistent, resulting in inaccurate predictions. The analysis further highlights that many correlations are overly empirical or based on narrow experimental conditions, limiting their applicability to diverse heat exchanger geometries. A key contribution of this work is the unique visual comparison of the correlations, providing a detailed depiction of their structural characteristics and offering more precise insights than those available in previous studies. © The Author(s) 2025.