Lakshminath Bezbaroa Central Library Digital Repository
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Recent Submissions
Thermoeconomic optimization studies of the refrigeration systems using metaheuristic techniques
(2023) Nagraj, Makkitaya Swarna
Refrigeration systems play a crucial role in maintaining thermal comfort by removing excess heat from enclosed spaces. These systems are vital for various applications, from cooling buildings to preserving perishable goods. The primary goal is to provide a cooling load to the evaporator through chilled water to maintain a specific temperature within the enclosed space. Among the various refrigeration systems, the vapor compression refrigeration system (VCRS) stands as the most widespread choice due to its high coefficient of performance (COP). However, VCRS consumes a significant amount of electricity because of its compressor, contributing indirectly to substantial CO2 emissions. To address the issues of energy consumption and CO2 emissions, researchers have turned their attention to refrigeration systems driven by alternative low-grade energy sources, such as vapor absorption refrigeration systems (VARS) and vapor adsorption refrigeration systems. Unfortunately, these sorption technologies tend to suffer from lower efficiency compared to conventional VCRS.
Development of DNA Aptamers against selected Celiac disease epitopes in Glutenin
(2023) Kalita, Jon Jyoti
Celiac disease, an autoimmune enteropathy of small intestine is caused by the indigestible immunostimulatory peptide sequences present in gluten protein. Gluten is present in the cereals like wheat, rye and barley. Consumption of gluten free diet is the only option available for celiac disease patient. The immunostimulatory peptide sequences are present in both the gliadin and glutenin fractions of gluten. Prior research were emphasized on detection of gliadin protein mostly, by different methods including antibodies and aptamers. This thesis focuses on the in-vitro selection and characterization of aptamers against two 14 mer peptide sequences, one from the high molecular weight glutenin of wheat (Triticum aestivum), GQGQQGYYPTSPQQ (GQ-14), which contains a celiac disease epitope QGYYPTSPQ and the other from low molecular weight glutenin, SQQQPPFSQQQQPV (SV-14), which contains epitope PFSQQQQPV. The aptamer sequences apt_J91P (56 bp) and apt_M09P (76 bp) were selected through conventional SELEX method against peptide targets GQ-14 and SV-14 respectively. The binding characterization between apt_J91P and GQ-14 by ITC reveals the dissociation constant of 2.26 μM and 4.385 mM for the primary and the secondary site of binding respectively. The dissociation constants are 17.6 μM and 8.33 mM for the primary and the secondary site of binding between apt_M09P and SV-14 respectively. The binding was also characterized by circular dichroism spectroscopy. The limit of detections of the aptamers evaluated by direct-ELAA method are found to be 16.0875 μM for apt_J91P and 20.00 μM for apt_M09P against its respective targets. The preliminary investigations carried out to check the applicability of aptamers apt_J91P and apt_M09P in development of bioassays, gold nanoparticle based aptamer assay and aptamer mediated magnetic bead based extraction assay demonstrated target binding and specificity. The future scope include improvement the binding affinity of the aptamers for detection of the target peptides in real wheat samples.
Studies on Oil-Water Separation using Functionalized Magnetic Nanoparticle Dispersed Polymeric Membranes
(2023) Boruah, Pankaj
The motivation of the current research work is to develop a suitable method for the separation of oil from oily wastewater. A bio dispersant and a polymeric membrane were developed for the treatment of oily wastewater. The dispersant was developed by using a biopolymer as a bio-dispersant to stabilize crude oil. The polymeric membrane was developed using polyvinylidene fluoride (PVDF) and a lab-developed bioderived nanofiller, cellulose nanocrystal (CNC). Oligo lactic acid conjugate chitosan (OCH) were used as a bio-dispersant, an alternative to the synthetic chemical dispersant, which reduces the toxicity associated with chemical dispersants used in oil spill remediation. Results from the research indicate that byapplying Xanthan gum (XG) and OCH, a considerably stable crude oil-in-water emulsion was obtained, which remains stable for more than 3 weeks, as confirmed by the optical microscopic image. XG was used to increase the viscosity of water, which helps in further stabilizing the oil droplets. Degradation of these stabilized emulsion droplets was also carried out by isolated bacteria Pseudomonas aeruginosa CoE-SusPol3. The degradation percentage obtained from gas chromatography (G.C.) analysis for the stabilized emulsion is 74.31%, whereas the unstabilized emulsion is 34.06%. The in-situ production of biosurfactants from the isolated bacteria also assisted the degradation process by decreasing the surface tension of the crude oil. This research work addressed in this thesis also discussed the use of CNC as a bionanofiller, an alternative to the inorganic filler in the membrane. CNC was modified to form magnetic CNC (FeCNC) by single-step co-precipitation method, and a thin film membrane was prepared by adding FeCNC into the PVDF matrix. Detailed characterization for morphology, wettability, porosity and performance analysis was carried out for the composite membranes. For comparison, PVDF membranes with CNC were also prepared, and its detailed characterization and performance analysis were carried out. Further, the application of a magnetic field during membrane formation gives a new dimension to understanding the magnetoresponsive behaviour of FeCNCs for orientation at the surface of the membrane. More prominent finger-like structures were obtained for the PVDF/FeCNC membrane. This migration of FeCNCs to the surface improves the hydrophilic property of the membrane and thus results in superior antifouling properties. This current research helps in understanding the application of biomaterials for treating oily wastewater and how a bio-based material could be a potential and sustainable solution for treating oil spills instead of using harmful synthetic chemical dispersants. The reported findings also give an idea for the improvement of properties of the membrane by application of surface modification of the CNCs and how CNCs can be oriented at the surface of the membrane to improve the performance.
Heat Transfer Analysis of a Fin-tube Heat Exchanger using Shearthinning Fluid and Winglet Type Vortex Generators
(2024) Kumar, Dheeraj
The present thesis work investigated the effect of various shapes of winglets, such as delta winglet pairs (DWP), rectangular winglet pairs (RWP), and curved rectangular winglet pairs (CRWP), on the flow behavior of an aqueous solution of carboxymethylcellulose (CMC) through a rectangular channel with and without the inbuilt cylinders. Threedimensional numerical simulations were carried out for a range of Reynolds numbers (50-200) using aqueous carboxymethylcellulose, commonly known as non-Newtonian shear-thinning fluid as a working fluid. Nusselt number (Nu), friction factor (f), and the combined effect of Nu and f, commonly known as quality factor (Qf), were calculated and compared for each case. Additionally, the comparison is also made with the base channel considering a dimensionless number (η) defined as (Num/Nuo)*(fo/f)0.33. As well, an investigation was conducted into the impact of attack angle, winglet placement, and tube placement on the thermohydraulic performance of the channel. The fintube heat exchanger (FTHE) performance parameters were effectively compared and evaluated using an aqueous
solution of CMC and water. It was discovered that incorporating DWP in FTHE improves overall performance compared to RWP. Still, when only heat transfer applications are considered, RWP outperforms DWP. When comparing the thermohydraulic performance, the use of CRWP is unequivocally superior to RWP. The former option provides a more efficient and effective means of achieving the desired outcomes. Reducing the attack angle improves performance up to a limit, but further decrease reduces performance. Utilizing an aqueous solution of CMC as a working fluid has been established as a practical approach to augment heat transfer while simultaneously reducing pressure drop. Based on the thorough evaluation of the overall performance, it is evident that FTHE with winglets significantly outperforms the base channel. Staggered tube configurations of FTHE show better thermal performance than inline tube configurations. They generate higher values of critical parameters such as Nu, f, and Qf, which enhances the efficiency and effectiveness of relevant applications.
Development of Seismic Source Zonation Maps, Seismic Hazard Maps (Using Multiple Approaches) and GMPE for North East India
(2024) Borah, Niranjan
The region of North East India (NE India) exhibits a notable high occurrence of seismic activity. The history of the past devastating earthquakes in the region clearly shows the need for a preparation plan to mitigate the disaster caused by EQs. For EQ disaster mitigation, seismic hazard levels within the region are required to be estimated. However, incomplete earthquake data poses considerable challenges to understanding seismic hazards in the region. This thesis aims to address this gap through a comprehensive analysis to enhance seismic hazard analysis in NE India. The study performed the delineation of seismic source zones using clustering techniques and spatial analysis based on past EQ locations and seismicity parameters. This process allows us to achieve a better understanding of seismic activity distribution in the region. The present work conducted probabilistic seismic hazard analyses (PSHA) using traditional and kernel-based methodologies considering these source zones. While performing the Kernel-based PSHA, the present work utilized information about the past paleo EQs along with their uncertainties related to locations and magnitudes. The results highlighted varying seismic hazard levels across NE India, with the eastern region of Manipur and the southern region of Nagaland exhibiting the highest hazard due to significant past earthquake occurrences and the size of seismic events. On the other hand, certain areas in Sikkim, Arunachal Pradesh, and Assam showed comparatively lower seismic hazard levels. Further, the present work performed the deaggregation of seismic hazard levels focusing on key cities in NE India, explaining the contributions of different seismic sources and different magnitudes of EQs to the overall hazard level. It was found that the contributions of strong EQs are mainly controlling the seismic hazards in the region. Additionally, this thesis presents a ground motion prediction equation (GMPE) designed for Northeast India. This GMPE is developed based on regional parameters and synthetic ground motions, allowing for the prediction of ground motion levels across different soil conditions. Validation against regional records confirms the efficacy of the proposed GMPE, instilling confidence in its utility for seismic risk assessment and engineering design purposes in the region. Overall, this thesis provides valuable insights into the region's seismic hazard scenery by combining methodologies for seismic source zonation, probabilistic seismic hazard assessment, and ground motion prediction. The findings can be utilized for urban planning, infrastructure development, and disaster preparedness efforts to develop resilience in the face of seismic events in Northeast India.