School of Energy Science and Engineering

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    Aerodynamic Design and Wind Tunnel Testing of Small Horizontal-axis Wind Turbine for Multirotor Configurations
    (2023) Siram, Ojing
    The present investigation explores the applicability of small horizontal-axis wind turbines (SHAWTs) to be employed as a power-generating source in places where Energy Science and Engineering demand isminimal or as a potential off-grid power source. The design and testing of SHAWT have been carried out at low λ (0.5 < λ < 6) and low Re (0.3×105 ≤ Re ≤ 3×105) conditions. The rotor blades were designed using the blade element momentum theory and fabricated using the 3D printer. The rotors’ performance was tested in the wind tunnel using the rotary torque sensor (RTS). Based on the literature review, airfoil E216 (M1), SG6043 (M2), NACA63415(M3), and NACA0012 (M0) have been chosen for developing the model rotors. From BEMT analysis and experimental investigation, the M1 rotor shows maximum power coefficient of 0.37 and 0.34, respectively. The complexity of the BEMT rotor necessitates the development of a non-BEMT rotor, which in the present study are straight and linear tapered (SLT rotors). The SLT rotors with the root-to-tip chord (Cr/Ct) of 1:1 show favourable results. Furthermore, an in-depth investigation of wake propagation using particle image velocity (PIV) has been carried out. The near wake (x/R < 6) study shows the formation of a W-shape. The time-resolve and timeaveraged stream wise PIV assessment reveal Gaussian-like (skew) distribution and the presence of two opposite crests, marking the flow movement. The high-fidelity PIV data were then used to develop an ANN-based wake model. It is observed that experimental and ANN-based models can produce much better and more reliable results than their analytical counterparts.
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    Applications of Passion Fruit Extracts as Bioactive Pharmaceuticals, Biodiesel Additive for Oxidation Stability and Corrosion Resistance
    (2023) Purohit, Sukumar
    Fruits and vegetables are frequently consumed because of their contents - minerals, dietary fibers, vitamins, and antioxidants which are beneficial for the health. In developing countries there are very limited to negligible waste management policies. As a result, most of the waste materials are directly exposed to the open environment causing severe environmental pollution. Agro-waste materials are having enormous potential for valorization as they contain abundant bioactive phytochemicals, including polyphenols, anthocyanins, tannins, glycosides, vitamins, alkaloids, and many more. These compounds have also profound therapeutic values as antidiabetic, antimicrobial, anticancer, and so on. Moreover, the natural antioxidant extracted from this waste can also be utilized as natural additives to second-generation biofuels (biodiesel) for their quality improvement as oxidative stabilizers and corrosion inhibitors. Northeast India is bestowed with two biodiversity hotspots with variety of flora and fauna. Passion fruit is a less popular plant cultivated in these regions. The main edible part of this fruit is its flavourful and nutritious juice. The rest of the parts i.e. rind and seed make upto 60% of the total weight of fruit and are disposed directly without any treatment.Thus, the present work aims to explore the antioxidant potential of these two varieties of passion fruit (yellow and purple passion fruit) from Northeast India for various applications. The entire thesis work has been divided into four major parts. The first part of the thesis presents the collection, morphological and physico-chemical characterization of the rind and seed of yellow passion fruit and purple passion fruit collected from Northeast India. The second part of the thesis discusses the phytochemical profile of the rind and seed extracts from yellow and purple passion fruit and their role as antioxidant and antibacterial agents. In this context, the samples were extracted using four different solvents such as ethyl acetate, acetone, methanol and water. Phytochemical mining study revealed presence of many phytochemicals from the passion fruit sample. Further, in the subsequent part of the thesis, role of the antioxidant rich passion fruit extracts for increasing oxidation stability of different biodiesel was elaborated. Biodiesel is prone to oxidation because of high moisture content and unsaturated fatty acid composition.
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    Biochar production from pyrolysis and co–pyrolysis of biomass blends: analysis, characterization and applications
    (2021) Muigai, Harrison Hihu
    Co–pyrolysis of biomass is a promising technology capable of producing compatible substitutes for petroleum derived fuels and chemicals. To manufacture the renewable fuel precursors and chemicals on a large scale, the process needs to be cost–competitive. However, co–pyrolysis has not gained significant commercial success because of complex feedstock chemistry. Computational models help in efficient design of reactor, and understanding complex processes involved during pyrolysis and co-pyrolysis. However, all integral isoconversional methods are based on the assumption that activation energy remains constant over the whole interval of integration. In practice, such behaviour is not observed. Especially, for the biomass, the error can be as large as 20–30% in the case of strong variations of activation energy with conversion. The International Confederation for Thermal Analysis and Calorimetry (ICTAC) has recommended the use of more accurate equations and performing an iterative correction procedure for the value of activation energy. To correct these errors, ICTAC has recommended to use advanced methods that work with small conversion intervals such as Vyazovkin_advanced isoconversional model (AIC) and Distributed Activation Energy Model (DAEM). In this the present study various aspects of biomass pyrolysis and co–pyrolysis processes were analyzed. Physico–chemical characterization and kinetic analyses of three biomass, viz. invasive species of water hyacinth (WH), Thevetia peruviana (TP), and industrial by–product of sugar cane bagasse (SCB) to assess their potential as feedstock for pyrolysis were investigated. Four isoconversional methods, viz. Kissinger–Akahira–Sunose (KAS), Friedman, Ozawa–Flynn–Wall (OFW), and advanced Vyazovkin_AIC were used to determine the kinetics triplets of thermal conversion at three different heating rates 10, 30 and 40 °C min-1. The activation energies for raw biomass viz. WH, TP and SCB determined using the four isoconversional methods were found to be in the range of 188–330, 182–389, and 193–293kJ mol-1, respectively. In the case of biomass blends the activation energies for binary blends of WHSCB, WHTP, TPSCB were observed to be in the range of 123–238, 128–273, and 125–236kJ mol–1, respectively. For ternary blends of WH111, WH211 and WH311, activation energy varied in the range 120–194, 123–247, and 122–195kJ mol–1, respectively. The characterization and kinetic analysis of all biomass essentially demonstrates their potential as feedstock for pyrolysis and co–pyrolysis. Pyrolysis was carried out in a fixed batch reactor at 350°C and 550°C with a heating rate of 20°Cmin-1. Biochars were characterized for proximate and ultimate (elemental) analysis, and also using standard techniques (SEM, EDX, TGA, BET, XRD, and FTIR). Biochars produced from three different biomass, viz. water hyacinth (whole plant and its components), yellow oleander and sugarcane bagasse, and their comparative assessment for potential application in agronomy and engineering were investigated. Biochar produced from sugarcane bagasse at 550oC possessed best properties: fixed carbon (77.42 %), bulk density (0.13 kg/m3), BET surface area (17.78 m2/g), pore size (12.86 nm), total pore volume (0.025 cm3/g), calorific value (30.18 MJkg–1), ash content (1.16 %), and moisture content (2.03 %). Co–pyrolysis of ternary blend obtained from biomass viz. water hyacinth, Thevetia peruviana and sugarcane bagasse was carried out in a fixed bed reactor. The optimum process conditions were determined using response surface methodology (RSM). The optimum conditions for co–pyrolysis based on two responses viz. yield and higher heating value were obtained at the temperature of 368 C, heating rate of 16.33°C min-1 and residence time of 61min. The present study is useful for the understanding intensification of co–pyrolysis process and applications of biochar produced from noxious weeds and waste.
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    Biodegradation of polycyclic aromatic hydrocarbons in contaminated wastewater and biodiesel production using the oleaginous bacterium Rhodococcus opacus
    (2019) Goswami, Lalit
    Polycyclic aromatic hydrocarbons (PAHs) represent a unique class of ubiquitous semi-volatile organic contaminants, well-known for their persistent, bioaccumulative, toxic, carcinogenic, teratogenic and mutagenic nature. In the present study, a hydrocarbonoclastic oleaginous bacterium Rhodococcus opacus, was investigated for its potential to simultaneous degrade naphthalene, anthracene, phenanthrene and fluoranthene as model PAHs, in single, multi-component and cocontaminated heavy metal system. In single-component system containing minimal salt medium with all the four PAH compound as the sole source of carbon and energy and at an initial concentration in the range 50-500 mg L-1, R. opcaus was capable of degrading 58% - 83.8% of PAHs along with the lipid accumulation in the range 72.4% (w/w, CDW) within 7 days. In the multi-contaminated system, a maximum removal of 91.6%, 82.3% and 80.7% was achieved for naphthalene, phenanthrene and fluoranthene, respectively. The individual effect of PAH concentration was found to be more significant than 2-way and 3-way interaction effects on PAHs biodegradation. The biodegradation efficiency in the mixture was mainly affected by initial concentration and aromatic complexity of the PAHs. Furthermore, effect of six different heavy metals individually has depicted the following order on PAH biodegradation and lipid accumulation: Cd > Ni > Pb > Cu > Zn > Fe. In order to enhance PAH bioavailability by R. opacus, biochar derived cheaply from biomass gasification waste was evaluated and has shown an enhancement in PAH biodegradation in the range of 79.6% to 92.3%. The valorization of biomass gasification wastewater (BGWW) for lipids accumulation by Rhodococcus opacus was further examined.
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    Biohydrogen production from crude glycerol: Process optimization and intensification
    (2018) Sarma, Shyamali
    The proposed thesis work is aimed at optimization and intensification of a biochemical process for producing hydrogen from biodiesel–derived crude glycerol. The micro–organism used for in this study is Clostridium pasteurianum, which has a higher potential for biohydrogen production. This study aims in enriching H2 producing Clostridium pasteurianum by optimizing the physio–chemical parameters for maximal H2 production by using response surface methodology. This is followed by kinetic and thermodynamic analysis of hydrogen production for both pure and crude glycerol as substrate for fermentation. Similarly statistical optimization of the media components was also considered as one of the approach to intensify H2 production. Further to maximize valuable metabolite production, extensive analysis and understanding of metabolic pathways is required so as to redirect the cellular metabolic pathways primarily towards its production. An in silico metabolic flux model has been formulated for this analysis that determines the complete intracellular fluxes of all metabolites from experimentally measured fluxes. This methodology was used for comparative analysis of mechanical shaking and ultrasound-assisted fermentation for H2 production. The flux analysis results were further corroborated by targeting the genes involved in glycerol-hydrogen pathway of C. pasteurianum which involved overexpression of Fe-only hydrogenase encoded by hydA and the enzymes involved in glycerol metabolism encoded by dhaD and dhaK. The hydrogen production efficiency was compared between the wild type and recombinant strain of C. pasteurianum using crude glycerol as the substrate.
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    Butanol Production from Rice Straw : Process Development and Optimization
    (2012) Ranjan, Amrita
    Abstract not found
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    Charging infrastructure planning for electric vehicles
    (2020) Deb, Sanchari
    The ever increasing energy demand accompanied by fossil fuel depletion and environmental degradation has paved the path of transportation electrification. Electric Vehicles (EVs) are environmental friendly alternative to conventional Internal Combustion Engine (ICE) driven vehicles. For large scale deployment of EVs sustainable charging infrastructure needs to be developed. The charging station placement problem is a complex problem involving power distribution network and road network. Charging stations must be placed in the distribution network in such a way that the negative impact of placement of charging stations on the operating parameters of the distribution network is minimized. Also, the location of charging station must be optimized considering the route behavior of EV drivers and charging demand of the EVs computed based on the driving range of the EV. Hence, motivated by all the aforementioned factors this thesis aims to delve into charging infrastructure planning for EVs. The thesis proposes single-objective, multi-objective as well as robust two-stage formulation of charging station placement problem. Moreover, hybridization of Chicken Swarm Optimization and Teaching Learning Based Optimization Algorithm (CSO TLBO) is proposed for solving the charging station placement problem. The proposed formulations of charging station placement problem are validated on superimposed 33 bus distribution and 25 node road network, city of Tianjin, and highway network of Guwahati.
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    Clean Development Mechanism Potential of Compression Ignition Diesel Engines Using Gaseous Fuels in Dual Fuel Mode
    (2011) Sahoo, Bibhuti Bhusan
    The climate change problem results from the concentration of greenhouse gases (GHGs) in the atmosphere. The purpose of the Clean Development Mechanism (CDM) is to promote clean development in developing countries, and is based on the idea of emission reduction DproductionD. These reductions are DproducedD and then subtracted against a hypothetical DbaselineD of emissions. The fossil gasoline and diesel petroleum fuels used in internal combustion (IC) engines are one of the contributors to the global environmental degradation for their GHG emissions. Diesel engines contribute on important part of the worldDs transportation and industrial infrastructure, especially in heavy-duty equipment such as trucks, buses, construction and farm equipments, locomotives, ships etc. In the recent times, there are issues related to their GHG emissions such as, carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO). The use of alternative fuels is one of the most effective means of resolving this problem. Gaseous fuels receive more prominence in the domain of alternative fuels because of the possibilities of cleaner combustion. However, they are not suitable for compression ignition (CI) concept diesel engine when used alone due to their low cetane numbers and high auto-ignition temperatures. Hence, the CI engine of the Ddual fuelD approach plays a significant role in the efficient utilization of a wide range of gaseous fuels. During a dual fuel operation, a carbureted air-gas mixture is sucked and compressed like in a conventional diesel engine. The compressed air-gas mixture is fired by a small liquid fuel injection, pilot, which ignites spontaneously at the end of compression process. Biogas and syngas are the two alternative gaseous fuels examined in the present investigation. In general, Biogas is produced by Danaerobic digestionD process where the timing, pilot fuel mass inducted, intake manifold conditions, and type of gaseous fuel, have effects on the performance, combustion and emission characteristics of dual fuel diesel engines. However, the systematic investigations of individual parameters relevant to engine characterization have not been reported exhaustively in the literature. The second law analysis or evaluation of available energy determines the maximum possible performance of a thermodynamic system. In addition, impact of process change in the system in terms of system losses is also assessed. These findings help in reducing the availability loss to improve the performance of the engine in terms of efficiency and power output. However, there were only few literatures accessed on availability analysis of dual fuel engines. Therefore, the present contribution is focused to perform a systematic experimental investigation including the thermodynamic behavior of diesel engine under dual fuel mode. To accomplish the above problems of diesel engines, few additional components such as gas mixer and gas carburetor were designed, developed and incorporated into the base engine setup for executing the dual fuel operation. Experiments were conducted on a modified engine test unit so as to run biogas and syngas under dual fuel operations. The base diesel engine is a single-cylinder, constant-speed, water-cooled and direct-ignition diesel engine with a rated power of 5.2 kW at 1500 rpm.....
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    Cyanobacteria based photosynthetic microbial fuel cell : Development and application for sensing alcohol
    (2018) Kaushik, Sharbani
    The major objective of the present study is to develop an efficient photosynthetic microbial fuel cell (PMFC) using cyanobacteria as anodic catalyst with a further aim of utilizing this energy generating device for sensing applications. One of the key issues to make the bacterial catalysts effective for generating power in microbial fuel cell is the proper electrical communications between the bacterial cells and the conductive electrode of the fuel cell device. We proposed the direct electron transfer (DET) as the guiding principle for channelizing the cellular electrons to the anode for which, setting up of cyanobacteria biofilm on the anode was considered as a suitable strategy to comply the principle. We explored different synthetic and natural polymeric thin films for their rapid biofilm promoting abilities of cyanobacteria, Synechococcus sp. For a comparative analysis, the study was extended to two commonly available bacteria, namely, Escherichia coli and Lactobacillus plantarum. The activating role of different polymer thin films coated over polystyrene support on the Synechococcus sp. biofilm growth was examined concurrently by measuring biofilm florescence using a dye and by measuring cell density in the isolated biofilm. Compared to blank (no coating), the increase in biofilm formation (%) on silk, chitosan, silk-chitosan (3:2) blend, polyaniline, osmium, and Nafion films were 27.73 (31.16), 21.55 (23.74), 37.21 (38.34), 5.35 (8.96), 6.70 (6.55) and (nil), respectively with corresponding cell density (%) shown in the parentheses.
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    Design and Development of Hybrid Nanomaterials for Efficient Photocatalysis
    (2024) Devi, Thongam Debika
    Water is our life and its quality degradation has imposed a major threat to the health and environment with the emerging contaminants. Photocatalytic advanced oxidation processes (AOP) using reactive oxygen species (OH¯, •OH, H2O2, HO2•, O2•¯, O22¯) provide complete degradation of these persistent pollutants by using nanomaterials triggered by light absorption. However, its real-time application is limited by the use of high-power light sources to trigger the reaction and its limited performance. Thus, this thesis focuses on understanding and addressing these bottlenecks by― (a) designing and developing a sunlight-responsive photocatalyst to harvest natural sunlight, (b) developing heterostructure photocatalysts for enhanced efficiency by developing interfacial charge transfer, and (c) studying and discovering ways to enhance charge transfer by manipulating heterostructure photocatalyst responsive to natural sunlight. To achieve efficient photocatalysis, different sunlight-responsive photocatalysts were synthesized by varying― synthesis mediums and methods introducing surface defects and producing different nanoparticle morphologies. The dependence of the charge transfer, charge carrier lifetimes, surface structures, induced defects, and morphologies on the photocatalytic efficiencies were discussed elaborately. Variable ZnO samples were synthesized using DMF or DEG solvents using solvothermal and chemical synthesis methods showing different properties― morphologies, surface, and chemical properties. The influence of the charge transfer pathways in the photocatalytic efficiencies is discussed and explored with different charge transfer methods― self-assembled ZnO nanoparticles on three electronically different SWCNTs (metallic-SWCNT/ZnO, semiconducting-SWCNT/ZnO, and pristine-SWCNT/ZnO); Type I ZnO/Fe3O4 and Type II ZnO/TiO2 composite heterostructures; g-C3N4 & Z-scheme g-C3N4/ZnO composites, and other composites― g-C3N4/SWCNT, and g-C3N4/ZnO/SWCNT. By taking RhB as a model pollutant, these nanoparticles were used as the floating photocatalyst by coating on the face-mask fabric showing variable efficiencies up to 99% of 10 ppm RhB degradation within the 100 min natural sunlight exposure.
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    Design And Fabrication Of Solid State TiO2|Ag Structure For Developing Efficient Plasmonic Photo-Electric Conversion Device
    (2024) Devi, Kshetrimayum Priyalakshmi
    The global shift towards renewable energy sources, propelled by environmental concerns, has ignited a surge in research aimed at developing efficient solar energy technologies. This thesis is dedicated to the creation of a solid-state plasmonic energy harvesting device using low cost methodologies. Initial simulations compare various noble metal nanoparticles for their plasmonic resonance properties, with silver identified as particularly advantageous due to its sensitivity and electronic characteristics. Semiconductor substrates are synthesized through a simplified Sol-Gel technique, resulting in the production of TiO2 thin films tailored for solar applications. Subsequently, a solid-state energy harvesting device is fabricated, leveraging metal/semiconductor heterojunctions to achieve promising cell performances. Furthermore, the thesis delves into an environmentally friendly approach to synthesizing silver-graphene nanocomposites, which holds significant potential for enhancing device efficiency. These findings represent a significant stride forward in the design and implementation of efficient plasmonic energy harvesting devices, paving the way for sustainable advancements in solar power generation.
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    Design and Implementation of Estimators and Controllers for a DFIG-based Wind Energy Conversion Systems
    (2021) Mondal, Prosenjit
    The effective operation of a typical doubly-fed induction generator (DFIG)-based wind energy conversion system (WECS) requires efficient control of the two power electronic converters connected back-to-back. Out of these two converters, one converter is tied to the grid or the stator of the DFIG and is called active front-end converter or grid side converter (GSC) or stator side converter (SSC), and another one is tied to the rotor of the DFIG and is called rotor side converter (RSC). The present thesis mainly focuses on the design of controllers and observers for the DFIG. The efficient control of the GSC depends upon the accurate information on the phase and frequency of the grid voltage, which can be estimated through a phase-lock-loop (PLL) system. Hence, a modified synchronous reference frame (SRF)-based PLL technique is proposed to estimate the phase and frequency of the grid. The estimated phase from the proposed PLL is utilized to convert the three-phase sinusoidal variables in the stationary reference frame (abc) of the grid (voltage and current) to two-phase stationary DC variables in the synchronously rotating reference frame (dq). The dynamic model of the GSC in dq-reference frame is utilized here to develop the controllers for the GSC. Two current control algorithms are proposed to control the active and reactive grid currents of the GSC, and one voltage control algorithm is proposed to control the DC-bus voltage of the GSC. One of the current controllers is based on adaptive multiple-input multiple-output (MIMO) control, and the other current controller is based on first-order sliding mode control (FOSMC). The developed voltage controller is based on an extended state observer (ESO) augmented with an adaptive control technique. Efficient control of the RSC depends upon the accurate information on the rotor speed and rotor position/angle, which can be measured directly by a rotary encoder. However, the failure-prone nature of these encoders makes the system unreliable; hence, reliable solutions in the form of rotor speed and position observers are proposed in this thesis. Two observers are developed using the dynamic model of the DFIG. The stator current and rotor flux are used as the states for both the observer models. The first observer is based on the first-order sliding mode observer (FOSMO), and the second observer is based on second-order sliding mode observer (SOSMO). The performance of these observers is also validated in real-time with close loop terminal voltage control of a standalone DFIG system.
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    Design, Analysis and Implementation of Bridge Configured Winding in Switched Reluctance Motor for Self-Bearing Operation
    (2021) Ahmed, Firdausa
    With the advancement of science and technology, the demand for rotating electrical machines with a compact drive system has been on the rise. Recently, SRMs have become a major contribution in areas where high starting torque and high rotational speed are required at a low cost. However, a higher rotational speed often shortens the life of mechanical bearings and limits the high speed ability of such motors. Such a situation demands an electrical motor, which can avoid contact between the bearings and shaft to reduce the wear and tear of the mechanical bearings. One such effort by researchers has been made by introducing magnetic bearing in electrical machines and another is the integration of bearingless technology with machines. In this thesis, a specialized stator winding called Bridge Configured Winding (BCW) has been proposed for Switched Reluctance Motor (SRM) which can be used to generate both torque and controllable levitation/radial force using a single set winding and thus provide a cost-saving solution. The winding scheme forms two sets of terminals in each phase, one for torque supply and one for levitation supply. It provides the flexibility to operate as a normal motor when the bridge terminals are not connected. A mathematical model of the proposed motor has been developed and verified using Finite Element Model (FEM). A step by step design methodology has been presented for incorporation of the proposed design in a hardware prototype. The thesis also presents a simulation model of a speed-current controlled drive system for the proposed motor. A real-time closed loop control of radial displacement using PID has been implemented and the capability of the BCW for both torque and radial displacement control has been experimentally validated.
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    Design, installation and assessment of a novel variable compression ratio mechanism for multifuel spark ignition engine
    (2017) Chaudhari, Ashish Jagannath
    The spark ignition engines are the most versatile in the arena of internal combustion engines. Petrol fuel based spark igniton(SI) engines are designed for the cylinder bore to stroke ratio(compression ratio), spark plug location which will initiate combustion faster with faster flame speed and develops flame kernel with minimum time during combustion. As per engine manufacturers catalogue, the specified octane petrol is the best for the particular engine. In this regards, if the octane rating of the fuel changed, then the engine will not perform with the maximum efficiency. However, if there are some structural alterations are carried out as per fuel, load and speed, then the higher octane fuel can be utilized to its maximum performance. In order to achieve this objective, the novel variable compression ratio (VCR) mechanism accompanied with novel variable spark plug location (VSPL) is designed and developed which could be installed further on SI engines for online variation of VCR and VSPL. Gaseous fuels are high octane ratings and could be a good source of alternative energy source. Knowing this, the non renewable gas LPG and renewable raw biogas (52% CH4+46% CO2) are being tested in engine for VCR, VSPL and in combination with EGR. The results recommend for continuous variation of CR accompanied with VSPL as per speed, load and EGR level could certainly achieve best performance in case of both fuels.
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    Design, Optimization, and Intensification of a Biological Gas to Liquid (BioGTL) Process for Methane Conversion to Methanol
    (2024) Priyadarshini, Aradhana
    This study investigates the methane bioconversion to methanol using biological gas-to-liquid (BioGTL) technique and especially addresses the United nation’s SDG 7 (Affordable and clean energy) and SDG 13 (Climate action). The principal aim of the present thesis is to design, optimize and intensify a bio-process for conversion of methane into methanol. Chapter 1 introduces and discusses impact of methane in climate change and why methane bioconversion to methanol is essential. The critical bioconversion of methane to methanol is made possible by soluble methane monooxygenases (sMMO) and particulate methane monooxygenase (pMMO). Chapter 2 studies and reports the potential of methanotrophic consortium enriched from rice field soil in methanol production. The consortium achieved a high methanol production titre of 130 mM (4.16 g/L). The maximum methanol titre of 160 mM was obtained using the Methylomicrobium buryatense 5G. Further, Methylotuvimicrobium buryatense 5GB1C was studied for their methanol accumulation capability in Chapter 3. This study attempted to maximize the methanol production using statistical optimization of the crucial fermentation parameters (phosphate buffer concentration, pH and temperature) resulting in a methanol titre of 8.54 mM in 24 h. Further investigation employed a methanol dehydrogenase inhibitor to prevent methanol breakdown, leading to an increased accumulation of 10.37 mM. The process was scaled up to a 3.7 L bioreactor, and significantly improved both methanol concentration (23.7 mM) and methane conversion efficiency (47.8%).
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    Design, Simulation and Experimental Investigation of High Temperature Solid-state Sensible Heat Storage Systems
    (2020) Vigneshwaran, K
    The work on the thesis is framed to propose high-temperature thermal energy storage, mainly focusing on the design, development and performance investigation of solid SHS. A high-temperature test facility has been built to study the performance characteristics of the TES modules. In the initial phase of research, the study focused on detailed experimental and numerical investigations on a cast steel based sensible heat thermal energy storage system using air as a heat transfer fluid. A dedicated test facility has been designed and developed for studying the performance of the storage system operating in the temperature range of 393 K to 573 K. Three-dimensional (3-D) and one-dimensional (1-D) models are developed for predicting the heat transfer characteristics of the storage system. The developed storage prototype has a shell and tube configuration having 19 passages in the tube side for heat transfer fluid flow. The performance of the storage system during the charging and discharging processes is analysed by varying the operating temperature range and flow velocity of air. The heat transfer characteristics of the system in terms of axial and radial temperature variations are recorded and analysed. Both the experimental and 3-D simulation results show a significant temperature variation in the axial direction than radial direction. The charging and discharging rates are found to be faster at a higher flow velocity of air. The predictions from both 3-D and 1-D models are consistent with the experimental data. The validated 1-D model can be used for real-time monitoring, control, optimisation and integration with various storage applications. In the next phase of research, the work presents the concept of developing a cost-effective Concrete based Thermal Energy Storage (CTES) system by performing extensive experimental studies and numerical simulations. A stand-alone experiment facility to study the performance of high-temperature thermal energy storage system, which operates up to 773 K using air as the heat transfer fluid, has been developed. The CTES module is made of shell and tube configuration, where the concrete is filled in the shell side, and 22 air passages are provided on the tube side. The inlet air temperature and velocity are the decision parameters used for analyzing the thermal behaviour of the CTES module. From the spatial variations of temperature, it is observed that the heat transfer rate is uniform and faster along all radial planes, whereas, the heat transfer rate drops gradually along the length of the CTES module due to drop in Heat Transfer Fluid (HTF) temperature. The parametric investigation conducted shows that the charging and discharging times were reduced by approximately 48% and 29%, respectively, with a change in inlet temperature of 40 K and at a fixed air velocity of 2 m/s. A 3-D model for the CTES module developed using the finite element method has been validated with experimental results. The temperature contours plotted from 3-D simulation describes the spatial variation of CTES temperature at different inlet air temperatures. Further, a 1-D dynamic model has been developed, which is fast and accurate with a maximum error of ±4.9 K with reference to real-time experiments and provides a substantial scope of integrating the CTES with industrial applications. In the final phase of research, a comprehensive coupling strategy is developed to evaluate the performance of a multi-module SHS system using the 1-D dynamic model. The validated 1-D model developed in our previous studies are adopted to scale-up the heat storage capacity for large scale application. The SHS modules used in this study are made of materials such as cast steel, cast iron and concrete with the design similar to shell and tube configuration. Air is used as the heat transfer fluid at a velocity of 15.2 m/s. Six Cases are framed to evaluate the charging (493-573 K) and discharging (373-573 K) behaviour of SHS module coupling strategies in different series and/or parallel arrangements. The performance of the charging and the discharging processes for all the Cases are estimated and compared for forward flow and reverse flow patterns and reverse module arrangements. The cost of the net energy discharged (USD/kW-h) from each arrangement is evaluated. The result shows that the performance of Case 6 (three parallel channels, with two different SHS modules in each channel) is better in terms of heat transfer rate and however, the cost of net energy discharged in Case 6 is 62.26 USD/kW-h, which is very expensive. The Case 3 (six concrete in the series arrangement) can store and discharge more amount of heat with slow heat transfer rate, and the cost of net energy discharged in this Case is 1.18 USD/kW-h. The developed flowsheet models are highly beneficial for studying the performance of the different storage module arrangements along with large scale applications. The outcomes from the studies highlight that cast steel and concrete TES storage modules are the cost-effective and viable high-temperature storage option for multiple thermal cycles with excellent durability.
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    Development and Characterization of Advanced FO Membranes using Exfoliated 2D Nanomaterials for Energy Generation and Separation Processes
    (2023) Deka, Priyamjeet
    Water shortage has become a global problem due to the high human consumption, rapid industrialization and low availability of freshwater resources. Extensive efforts have been put forward by researchers to overcome the freshwater crisis by exploring new desalination techniques, and wastewater reuse without damaging the natural freshwater ecosystems. One such pivotal technology for purifying water was the membrane technology. Membrane technology is an emerging and advanced process that can provide a sustainable solution to desalination and wastewater treatment. Although pressure-driven membrane separation processes were used for producing freshwater, its high energy consumption prevent them from further employment. Hence, modification of existing membrane-based separation technology is required to overcome its demerits
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    Development and Performance Assessment of Gaseous fuel based Porous Radiant Burners
    (2023) Kumar, M Arun
    This thesis presents the development and performance testing of Porous Radiant Burners (PRBs) using different fuels, including LPG, natural gas, and biogas, for cooking and industrial applications. These PRBs show promise in enhancing thermal efficiency and reducing emissions compared to conventional burners. In addition, an analytical model was developed to determine the factors influencing the primary air entrainment in a PRB. And experimental investigations were performed to check the validity of the developed analytical expression. Further, performances of the developed PRBs were assessed in terms of thermal efficiency and emissions. Through experimental investigations, it was found that the developed LPG-PRB and NG-PRB, exhibit improved thermal efficiency and fuel savings. Furthermore, a BG-PRB cookstove for domestic use was developed and demonstrated substantial gains in thermal efficiency and reduced emissions compared to conventional biogas burners. Environmental and economic assessments of the developed PRBs were conducted, highlighting the environmental benefits and cost savings associated with the use of these innovative PRBs. This research work contributes to the sustainable Energy Science and Engineering transition and offers practical solutions for cleaner and more efficient Energy Science and Engineering utilization in cooking and Industrial applications.