Department of Chemical Engineering

Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

IITH encourages and supports&nbsp;<a href="https://iic-iith.netlify.app/index.html" rel="noopener noreferrer" target="_blank">innovation and entrepreneurship</a>&nbsp;at every stage. The minor program in entrepreneurship is open to all students of IITH, and many of the courses are offered by industrialists who are entrepreneurs themselves. There are various&nbsp;<a href="https://iith.ac.in/research/centres-incubators/">innovation centers and incubators</a>&nbsp;that promote entrepreneurship and help mentor young innovators. IITH has been very successful in building tie-ups with leading academic institutions around the globe.

IITH enjoys a very special relationship with Japanese universities and industries that goes beyond academic and research collaborations. In fact, some of the iconic buildings in IITH campus will carry the signature of Japanese architecture.

IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

The fluctuating feed solid contents usually cause instationarities in industrial hydrocyclone separation. This demands a controlling mechanism for stabilizing the separation effect. Understanding the transitional/dynamic behaviour is necessary to design such control mechanisms. In this context, the present paper is aimed to understand the dynamic behaviour of a large-scale 250-mm hydrocyclone in terms of air core development and solid concentration distributions using the modified mixture model coupled with large eddy simulation turbulence model. Numerically predicted two-phase flow field data is validated against laser Doppler velocimetry data at two axial positions. A close agreement is found between the modified mixture model predicted particle classification curve and experimental data. Longer residence time is observed with near cut size particle compared to the and fine size particles. Further, the analysis of the equilibrium radius of different solid particles inside the cyclone in the presence of turbulence is compared with the classical Kelsall experiments and observed that the classification of particles influenced by both the turbulent dispersion and the centrifugal force. Finally, the effect of feed solids concentration (10–50 wt%) on the hydrocyclone performance and particle segregation is also undertaken in this study. © 2019 Curtin University and John Wiley & Sons, Ltd.

World University root node

Asia-Pacific Journal of Chemical Engineering

The dynamic behaviour of a large-scale 250-mm hydrocyclone: A CFD study

Column flotation (CF) is widely using equipment in mineral processing since many years. ERT technique facilitates non-invasive and nonintrusive visualization of different parameters in a column flotation. The hydrodynamic investigation of two-phase and three-phase are studied using electrical resistance tomography (ERT) coupled with pressure transducers in laboratory column flotation. Bubble size distribution, bubble rise velocity and gas and solids hold-up hydrodynamic parameters are extensively used for column flotation design and performance evaluation. The effect of superficial gas velocity, feed flow rate and slurry height in the column on mean gas hold-up and its radial distribution has been analyzed for both two-phase and three phase flows. Influence of solid particles on gas hold-up and its complete elucidation of dispersion in the column are assessed. Experimental results show ERT coupled with PT is suitable as an online monitoring tool to provide useful information on the hydrodynamic parameters of the column flotation. The tomography images, which were generated using a modified sensitivity back projection algorithm, were employed to explore the parameter study in two phase flow in column flotation. Furthermore, the results also indicate that ERT is a very powerful tool for diagnosing the `inside' flow behaviour of gas-liquid two-phase and gas-liquid-solid three-phase flow in columns operating for a wide range of flow regimes. © IMPC 2018 - 29th International Mineral Processing Congress. All rights reserved.

IMPC 2018 - 29th International Mineral Processing Congress

Investigation of column flotation hydrodynamics using electrical resistance tomography coupled with pressure transducers

Flexibility of graphene (Gr) is partially credited to its two-dimensional (2D) molecular structure which resembles like interconnected unit of hexagonal carbon atoms ring. Therefore, to increase the flexibility of micromechanical beams, we analyze the influence of hexagonal shape of microcantilever beam without and with hexagonal hole of varying side length. To carry out the analysis, we first fabricate the hexagonal structure and perform measurement using laser vibrometer. Based on the measurement, we found that the presence of hexagonal holes make the beam flexible by two order of magnitude more than that of a conventional beam without holes. However, we found that the frequency of microcantilever beam with hexagonal shape decreases with increase in hole size. To undo the effect of hexagonal holes on microbeam frequency, we cover the microbeam with an electrospun cellulose acetate nanofiber mat (CAF). Based on the measurements, we found that the frequency can be increased more than that of a solid rectangular microbeam. Finally, we propose a finite element based methodology to model microbeam and nanofiber mat to compute their frequencies. Thus, based on the understanding developed in this work, this hierarchical structure of microcantilever beam with electrosun nanofibers can be used as a best candidate for utilizing it for the development of flexible sensors based on MEMS devices. © 2019 IOP Publishing Ltd.

Department of Physics

Fulltext

Materials Research Express

Frequency analysis of hexagonal microbeam with 2D nanofiber mat

In this paper, numerical simulation of magnetite, medium segregation and coal partitioning have been made in a 350 mm diameter cyclone. An attempt is made to assess the nature of impairment in efficiency in relation to the increasing amount of near gravity materials in coal. The CFD model approaches the Algebraic Mixture (ASM) model with the granular option and Reynolds stress model (RSM) to resolve the air core and turbulent mixing of the medium and coal particles. The partition characteristics of the DMC were modelled using both Lagrangian &amp; Eulerian particle tracking for particles ranging in size from 0.5 to 8 mm and in density from 1200 to 2000 kg.m -3 . Lagrangian frame work based Discrete Phase model used to simulate the coal particle trajectories inside the DMC and attempted to understand the residence time of different size and density coal particles. It was observed that coal particles having density near to separation-density (having fifty percent of probability to under flow and overflow) are exhibiting increased residence time than any density particles. As expected the smaller size coal particles shows higher residence time than the coarse coal particles. CFD simulations on effect of NGM mass fraction are simulated and analyzed using ASM model including for coal and magnetite. Coal particles with high NGM content show significant effect in misplacement of coal particles towards wrong products at all relative densities. The residence time of the particles increases because of its increased interaction with near dense particles. The effect of NGM fraction on overall cyclone performance as well as detailed flow assessment in terms of residence time distribution, NGM particle concentration profiles with respect to LZVV is presented. © IMPC 2018 - 29th International Mineral Processing Congress. All rights reserved.

Numerical simulation of the effect of near gravity density particles on the performance of DMC treating coal

Colloidal glasses are out-of-equilibrium in nature. When such materials are quenched from a shear-melted state into a quiescent one, their structure freezes due to entropic caging of the constituents. However, thermal fluctuations allow slow structural evolution, a process known as aging, in favor of minimizing free energy. Here, we examine the rheological signatures of aging, in a model system of nearly hard sphere colloidal glass. Subtle changes in the linear viscoelastic properties are detected with the age of the colloidal glass where viscous modulus shows a decrease with aging whereas the elastic modulus remains unaffected. This is associated with the slowing-down of long-time out-of-cage dynamics as the glass ages. On the contrary, nonlinear rheological measurements such as start-up shear flow, stress relaxation, and creep experiments show a strong dependence on sample age. Moreover, creep and stress relaxation experiments show ample evidence of avalanche type processes that occur during aging of colloidal glasses. Finally, comparison of creep and start-up shear flow measurements indicate that the latter is more energy efficient in inducing flow in colloidal glasses irrespective of aging dynamics. © 2019 Author(s).

Physics of Fluids

Rheological signatures of aging in hard sphere colloidal glasses

Carbon nanofibers (CNF) have shown to improve electrochemical performance when used as anode materials in Lithium-ion batteries. Bacterial cellulose (BC), which is naturally produced as a hydrogel, yields CNF upon drying followed by pyrolysis. The BC derived CNF, primarily involving freeze-drying, have been successfully tested as a potential anode material. However, in order to enhance the anodic performance, we need to tune the physiochemical properties of BC. This work is a first of its kind attempt to systematically study the effect of dehydration conditions (namely, oven and freeze drying) of bacterial cellulose hydrogel (produced using two bacterial strains) on the microstructural properties and electrochemical performance of as-derived CNF. Finally, we demonstrate the use of oven-dried bacterial cellulose as a sustainable and scalable precursor for CNF with a reversible capacity of 440 mAhg−1 at 0.2 C-rate with ∼99% coulombic efficiency after 100 continuous charge/discharge cycles. © 2019 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim

Department of Materials Science and Metallurgical Engineering

ChemistrySelect

Modulated Dehydration for Enhanced Anodic Performance of Bacterial Cellulose derived Carbon Nanofibers

We experimentally investigate the evaporation dynamics of sessile droplets with different compositions of ethanol-water binary mixture at different substrate temperatures. At room temperature, a binary droplet undergoes two distinct evaporation stages unlike only the pinned stage evaporation for pure droplets. In the binary droplets, the more volatile ethanol evaporates faster leading to a nonlinear trend in the evaporation process. At elevated substrate temperature, we observed an early spreading stage, an intermediate pinned stage and a late receding stage of evaporation. Increasing the substrate temperature decreases the lifetime of binary droplets rapidly. At high substrate temperature, we found that the lifetime of the droplet exhibits a non-monotonic trend with the increase in ethanol concentration in the binary mixture, which can be attributed to the non-ideal behaviour of water-ethanol binary mixtures. Interestingly, the evaporation dynamics for different compositions at high substrate temperature exhibits a self-similar trend showing a constant normalised volumetric evaporation rate for the entire evaporation process. This indicates that the evaporation dynamics of a binary droplet of a given composition at high substrate temperature is equivalent to that of another pure fluid with a higher volatility at room temperature. The evaporation rates of pure and binary droplets at different substrate temperatures are compared against a theoretical model developed for pure and binary mixture droplets. The model predictions are found to be quite satisfactory for the steady evaporation phase of the droplet lifetimes. © 2019 Elsevier Ltd

Department of Mechanical and Aerospace Engineering

International Journal of Heat and Mass Transfer

Evaporation of ethanol-water sessile droplet of different compositions at an elevated substrate temperature

A frame is called scalable, if there exists nonnegative scalars such that column weighted frame is tight. A scaling is called a minimal scaling if it does not contain a proper subscaling. We call a minimal scaling as a sparsest minimal if the cardinality of the support of the scaling is minimal. The objective of the present work is to find a sparsest minimal scaling. We also discuss the uniqueness of sparsest minimal scaled frames as a good candidate for incoherent tight frames in recovering sparse signals. © 2018 IEEE.

Department of Mathematics

2018 IEEE 3rd International Conference on Signal and Image Processing, ICSIP 2018

Incoherent minimal scaled frame

The objective of the present work was to fabricate poly(vinyl alcohol)-gellan gum nanofiber (PG-NFs) based scaffolds for tissue engineering applications. PG-NFs were fabricated via electrospinning and were characterized using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis. Physical properties including water solubility, swelling behavior, contact angle, apparent porosity, biodegradation, and conductivity studies were performed. SEM micrographs displayed long, uniform and randomly oriented PG-NFs of average diameter of 158 ± 23 nm with an interconnected three-dimensional network structure and FTIR study showed gellan gum interaction with PVA through hydrogen bonding. The degradation assay confirmed that as fabricated PG-NFs were stable in the aqueous medium without any significant weight loss. The apparent porosity of PG-NFs was 40%, and conductance was 126.93 pS. The PG-NFs was also proven to be non-toxic and biocompatible by supporting the growth of murine embryonic stem cells (ESCs), similar as control, upon culturing on the same. In summary, stability of PG-NFs in the aqueous medium and significant growth of ESCs in vitro on such 3D nanofibrous scaffolds make it a promising material for various tissue engineering applications. © 2019 Elsevier B.V.

Journal of Drug Delivery Science and Technology

Investigation of poly(vinyl) alcohol-gellan gum based nanofiber as scaffolds for tissue engineering applications

End functionalized polymer grafted nanoparticles (PGNs) interact to form bonds when their coronas overlap. The number of bonds formed at equilibrium depends on the structure of PGNs, polymer-solvent interactions, and nature of bonds. Here, we examine the effect of grafting density, bond energy, solvent quality, and length of grafted arms on pair interactions between PGNs. We employ a multicomponent model to capture the interaction between PGNs under varying conditions. Via computer simulations, based on the multicomponent model, we examine the evolution of the number of bonds formed between interacting functionalized PGNs. Based on the simulations we show that grafting density and bond energy have an opposing effect on the number of bonds formed at equilibrium. Furthermore, we show that the number of bonds formed at equilibrium changes nonmonotonically with a decrease in solvent quality. Specifically, for a transition from good to athermal solvent the number of bonds formed at equilibrium decreases, while a further decrease in solvent quality causes interacting PGNs to form excessive bonds. Finally, we also show that a change in length of grafted arms has negligible effect on equilibrium bond formation. Copyright © 2018 American Chemical Society.