Faculty Publications

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    Characterization of metal-PCMs for thermal energy storage applications
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Sudheer, R.; Prabhu, K.
    In recent years phase change materials have emerged to be ideal energy storage materials for their higher energy density over sensible heat storing materials. Use of phase change materials (PCM) have been successfully implemented at lower temperature applications with various organic compounds. On the other hand, high temperature applications have been solely dominated by various salts, their eutectics and mixtures as phase change materials. This work discusses the suitability of metals and alloys for thermal energy storage applications as the phase change material. Metals offer superior thermal conductivities with considerable energy density compared to salts. Here, two alloys namely, Sn-0.3Ag-0.7Cu (SAC) solidifying over 212-224°C and ZA8 (Zn-8%Al) solidifying over 378-405°C have been studied. Thermal analysis of PCMs using Computer Aided Cooling Curve Analysis (CA-CCA) and DSC technique were performed to predict the solidification path. In addition to this, Newtonian technique was employed to estimate the latent heat of fusion for these phase change materials. Cooling rate curves and Fraction Solid curves offered a better insight into their ability to receive and discharge heat over the concerned temperature range. © (2015) Trans Tech Publications, Switzerland.
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    MOGA and TOPSIS-based multi-objective optimization of wire EDM process parameters for Ni50.3-Ti29.7-Hf20 alloy
    (Elsevier Ltd, 2023) Balaji, B.; Narendranath, N.
    Conventional machining techniques face challenges in processing Ni-Ti-Hf alloys, which exhibit superior properties and are increasingly considered promising materials for high-temperature shape memory actuator applications. Thus, this article focuses on investigating the effect of Wire Electric Discharge Machining (WEDM) input parameters, namely discharge time (TON), pause time (TOFF), gap voltage (SV), and wire travel speed (WF), on the surface quality and shape memory properties of these alloys. These parameters were optimized to obtain a better removal rate (MRR) and surface finish quality (Ra) by employing a hybrid approach of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Multi-Objective Genetic Algorithm (MOGA). TON emerged as the most influencing parameter for both MRR and Ra, and the sample machined using optimal parameter setting, which had a MRR of 5.287 mm3/min and Ra of 2.335 µm, showed better surface quality with fewer surface defects and irregularities, lower recast layer thickness of 10.057 µm, and better shape memory properties with less than 15 % deviation in their latent heat of transformation values and a less than 5ºC change in their austenite and martensite transformation temperature values, which indicates MOGA was successful in finding a trade-off between the two responses. © 2023 Elsevier Ltd