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ThesisItem Open Access Impact of surfactant modified ferrite nanoparticles on mechanical and thermal characteristics of epoxy(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-09) Singh, Ashtosh Kumar; Saxena, RakeshPresent investigation deals with development of surfactant modified ferrite nanoparticles (FNs) to achieve the epoxy ferrite composites (EFCs) bearing enhanced dispersion and compatibility of filler with epoxy matrix. This has afforded a series of EFCs with improved tensile, bending, compressive and impact strength. EFCs has shown improved hardness with characteristic reduction in their wear loss. However, a marginal increase in thermal stability of EFCs has been observed. Formation of surface modified FNs (SFNs) and their compatibility with epoxy matrix was clearly revealed through Fourier transformed infra- red spectra. Diversified microscopic methods in combination with X-ray diffraction spectra, magnetometry and DC conductivity experiments reveals enhanced dispersion of SFNs into EFCs. The overall experimental outcome reveals that SFNs (2 phr) imparts improved dispersion, compatibility with epoxy matrix that leads to the formation of EFCs with improved mechanical properties and controlled wear loss. Study further reveals that, EFCs developed through SFNs were of improved durability over those derived from FNs under identical filler loadings. Study finally disclose the importance of surfactants as modifiers for magnetically active fillers such as ferrites and their similar analogues making them suitable for development of high performance polymer nanocomposites suitable for the appliances useful for transportation, stealth and energy management, and biomedical applications.ThesisItem Open Access Investigation of thermal characteristic behavior of rotating packed bed using air-water system(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-10) Saurabh; Murthy, D.S.The investigation of thermal characteristic behavior of rotating packed bed has been conducted in a three-tire approach. Initial testing for the feasibility of thermal responses in the device upon varying the mass flow rate and inlet temperature respectively gave the way for next level of investigation. Here in, the fluid’s mass flow rate ratio, fluid’s inlet temperature ratio, packing rotation and porosity were identified as input/ independent parameters; whereas, pressure drop across the packing, water temperature drop, and heat transfer rate are scheduled as the response variables. The computational fluid dynamics approach has been opted for the entire purpose as it proves beneficial in providing data pertaining to intricate locations that would otherwise have not been possible using conventional methods alone. The implementation of central composite rotatable design scheme has been made in order to obtain corresponding range of data for the analysis of independent parameters.Statistical interpretation of the data for significance of effects caused by the independent variables on to the thermal response variables has been discussed. The use of response surface methodology to discern the thermal behavior of rotating packed bed using surface contours has also been attempted. The vivid discussion of main effects and interaction effects plot is elaborately presented. The use of rotating packed bed secures an overall increment of 157% in the value of heat transfer coefficient for approximately the same temperature drop (~8 K) along with the volumetric reduction in packing/ fills, as high as upto 96.5%.These results justify not only the thermal process intensification in rotating packed bed, but also render sufficient encouragement for futuristic use of this device in the domain of heat transfer applications.ThesisItem Open Access Performance studies on a solar air heater having combined V and I shaped ribs(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Gangwar, Hitendra Pal; Pratihar, A.K.The use of artificial roughness on the underside of the absorber plate enhances the performance of the conventional solar air heater with little penalty of pressure drop. An experimental and CFD study on new roughness geometry in the form of combined V and I shaped ribs on the underside of the absorber plate has been carried out to increase the heat transfer and reduce friction factor in the present work. Experimental setup is designed and fabricated for the performance study novel roughness geometry for indoor conditions with a constant heat flux applied to the absorber plate. The experiments are conducted on three different relative roughness pitches of 20, 30, 40 and smooth plate for Reynolds number varying from 3500 to 10,500. Variation of Nusselt numbers (Nu) has been studied with Reynolds numbers and comparison has been made between roughened and smooth plate absorber. As a result of study, performance study, it has been found that the absorber plate having relative roughness pitch of 20 shows highest thermo-hydraulic performance. The highest thermo-hydraulic performance parameter is found to be 1.72 at Reynolds number (Re) of 10151 for roughness pitch of 20. Experimental results have also been correlated in terms of Reynolds number (Re) and relative roughness pitch (P/e) to develop new correlations of heat transfer and friction factor. The results of CFD analysis are found to be in good agreement with the experimental results for relative roughness pitch of 20. For rectangular duct having combined V and I shaped ribs on absorber plate, the highest enhancement in friction factor is found to be 3.77 times at Reynolds number 3569 as compared to smooth plate solar air heater. The highest increase in friction factor is found to be at relative roughness pitch of 20. The values of Nusselt numbers obtained from correlation lies within 0 to ± 5% of experimental values and the values of friction factor obtained from correlation lies within 0 to ± 12% of experimental values for the range of parameters studied in this work.ThesisItem Open Access Comparative study of Gas Metal and Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW) for aluminium alloy 3003-H2 using Taguchi method(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2018-08) Ram Gopal; Jadoun, R.S.Gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes are an efficient economical means of welding of ferrous and non-ferrous materials. GMAW and GTAW processes have a great potential for application in precision welding of aluminium alloy 3003-H2. The published literature reveals that no systematic effort has been made to study the GMAW and GTAW processes in a comprehensive manner by considering all performance characteristics to predict the quality of weld. Realizing the potential and importance of the GMAW and GTAW processes for precision welding of aluminium alloy, the present work aims at investigating the effect of various processes parameters on the quality of weld in aluminium alloy. Experiments were carried out in a phased manner and the work was divided into three parts i.e. using GMAW, using GTAW and comparison of GMAW & GTAW. Comparative study of gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) for ultimate tensile strength, impact strength and hardness have been performed by Taguchi method. The control parameters viz. welding current, welding voltage, welding speed, gas flow rate and root gap were chosen as welding input parameters. The materials used for this purpose were aluminium alloys of grades 3003-H2 as parent material and ER4043 as filler material (wire) having dimensions (100x40x5 mm). Helium and argon were used as a shielding gas. Filler wire 4043 of diameter 1.6 mm was used. An orthogonal array, L27 was used to conduct the experiments. Signal to noise (S/N) ratio and analysis of variance (ANOVA) were employed to study the welding characteristics. Optimization of parameters was done by Taguchi method using statistical software MINITAB-18. Confirmation tests were carried out to validate the experimental results. Welding voltage for UTS, welding current for impact and welding current for hardness of GMAW were found to be most significant factors. Similarly, welding voltage for UTS, welding speed for impact strength and welding current for hardness of GTAW were found to be most significant factors.ThesisItem Open Access Numerical investigations on ice slurry flow with different pipe geometries(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2018-01) Rawat, Kamal Singh; Pratihar, A.K.The use of ice slurry as a working fluid in secondary-loop of refrigeration system not only enhances the system performance but also reduces the refrigerant charge and its leakage to environment. Thus, presents exciting solution of the two pronged problem of energy and environment safety. Ice slurry can be transported through pipes, however, ice slurry flow is a complex solid-liquid two phase flow, which significantly differs from the single phase flow. During the ice slurry flow in horizontal pipe, the ice particles tend to float (due to density difference) towards the top of the pipe and different ice concentrations exist in the radial direction of the pipe. Depending on ice concentration distribution, the flow can be classified into four flow categories viz. homogeneous, heterogeneous, moving bed and stationary bed flow. The flow of ice slurry depends on various operating parameter viz. initial velocity, ice concentration, freezing point depressant concentration and particle size. As the flow of ice slurry through a pipe is a complex S-L flow, it is a formidable task to analyze this type of flow experimentally due to complexities in measurements and visualization. Therefore, a CFD model is developed to simulate the ice slurry flow in various flow regimes through various pipe geometries. In the modeling of ice slurry flow, various interfacial forces viz. drag force, lift force and turbulence dispersion forces are considered. The turbulence in the ice slurry flow is modeled by the per phase k-model. The CFD model has been first validated with the experiment results of the ice and sand-water slurry flow in various pipe geometries. After validation of the present model, the simulation of ice slurry flow has been carried out in four type of pipes; horizontal pipe, vertical pipe, 90o elbow bend pipe and 180o U-bend pipe. Simulation has been carried out to predict the critical velocity and the effect of different parameters on critical velocity in a horizontal pipe. For transportation of ice slurry, homogeneous and heterogeneous flow regimes are recommended therefore, investigation of ice slurry flow in these regimes has been carried out in different pipes to study the effect of different parameters. Apart from that, the effect of different bend radius ratios (R/r) on the ice slurry flow has also been investigated in bend pipes. The critical velocity is significantly influenced by the particle size. Critical velocity at 10% initial ice concentration increases from 0.4 m/s to 0.16 m/s with increase in particle size from 0.1 mm to 0.4 mm. The pressure drop for the heterogeneous slurry flow in both horizontal and vertical pipes increases with increase in initial velocity and ice concentration due to increase in the rate of interaction between solid-liquid and number of collisions among the particles and with wall increase which causing more frictional losses. Beside this, in vertical pipe pressure drop in case of downward flow is upto 12 % more in comparison to that in upward flow due to turbulence losses. In the ice slurry flow through bend pipes, centrifugal force acts on the fluid which results in secondary flow at the bend section similar to single phase flow. The value of pressure drop, velocity and particle distribution in the bend section is significantly affected by the secondary flow. However, the effect of secondary flow becomes less predominant at higher bend radius ratios.ThesisItem Open Access Effect of blending and cross-linking on thermal and mechanical properties of polyvinyl alcohol based composite reinforced with basalt fiber(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2018-09) Jain, Naman; Singh, V.K.Polyvinyl alcohol (PVA) is a synthetic, semi-crystalline, biodegradable and water soluble polymer having moderate mechanical properties.The aim of thesis is to improve moisture absorption, solubility, mechanical properties and thermal stability of PVA by blending it with different polymers. In addition, thermal cross-linking of the films has been studied by heating the films at 120ºC for 4 h. PVA was found to be completely soluble in water, while post blending solubility and moisture absorption of blended films is decreased. For Restriction of water absorption of PVA chemical cross-linking with hydrochloric acid (HCl) is done which is confirmed by FT-IR spectroscopy. Results suggest that due to the formation of cross-linked bonds thermal and mechanical properties of PVA based cross-linked compositeare improved as compared to pristine PVA due to which degradation temperature is increased as compared to neat PVA. The tensile strength of blended and cross-linked films was significantly higher as compared to neat PVA.Further improvement in physical, mechanical and thermal properties of cross-linked films is achieved by reinforcing nano-basalt fibers which result in 79.4% increased in UTS of PVA based cross-linked films. DMA analysis of blending and crosslinking films has been studied to determine the storage modulus, glass transition temperature and activation energy. Creep and recovery behavior were also examined to study the effect of stress and temperature on creep strain and burger model is used to study the creep data.ThesisItem Open Access Fabrication and characterization of novel liquid rubber modified epoxy(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-11) Gunwant, Dheeraj; Sah, P.L.A series of liquid rubber modified epoxies (LREs) were fabricated by dispersing pyrolysis derived liquid rubber (PLR) with concentrations ranging 0-25 wt. % into a commercially available epoxy resin (CY-230) followed by curing with triethylene tetramine (TETA, HY-951). The qualitative dispersion of PLR into cured epoxy was ascertained through atomic force microscopy (AFM) and DC conductivity. The nature of bonding of PLR with epoxy was studied using FTIR spectra. The LREs were cast into different dimensions according to ASTM D specifications. The effect of PLR on their mechanical and thermal properties has been evaluated. With PLR concentration, a regular decrease in hardness, tensile, flexural and compressive properties has been observed. This is attributed to the increase in size of phase separated rubber particles (RPs) as well as plasticization of epoxy matrix due to PLR addition. The impact strength and fracture toughness (KIC) of LREs improved gradually up to 15 wt. % of PLR concentration. This is attributed to the increase in size of plastic zone due to the presence of in the LREs. In order to correlate the improvement in impact strength and KIC values, specimens recovered from these tests were subjected to fractography using FESEM. Cavitation of RPs followed by shear yielding of epoxy matrix was observed to be the most prominent toughening mechanism in LREs. The effect of PLR on thermo-oxidative stability of cured epoxy as well as LREs was investigated through simultaneous thermogravimetric-differential thermal analysis-differential thermogravimetry (TG-DTA-DTG). Micromechanical modeling of LREs was conducted using a finite element (FE) model assuming bcc arrangement of RPs in epoxy matrix. The model was used to explain the lowering of stiffness using a novel scheme based on isotropic stiffness matrix and numerical homogenization technique (NHT). The model was employed to substantiate the experimental findings through stress analysis. Finally, the model was used to predict the effect of RP properties on the elastic properties and stress distributions in LREs.ThesisItem Open Access Thermo-hydraulic performance studies on solar air heater having rectangular sectioned tapered rib-roughness(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-08) Gupta, Akash Deep; Varshney, L.ThesisItem Open Access Studies on diesel alcohol emulsification and performance evaluation of C.I. engine on emulsified fuels(Govind Ballabh Pant University of Agriculture and Technology;Pantnagar, 2005) Gupta, Vijay Kumar; Agrawal, P.K.
