http://localhost:8081/jspui/handle/123456789/14 Sun, 19 Apr 2026 21:01:42 GMT 2026-04-19T21:01:42Z http://localhost:8081/jspui/handle/123456789/20431 Title: ENHANCEMENT OF HEAT TRANSFER DURING FILM CONDENSATION OF R32 VAPOUR OVER SINGLE HORIZONTAL INTEGRAL-FIN TUBES Authors: Mohammed, Ibrahim Mustefa Abstract: The demand for energy conservation and environmental issues have become a critical global concern, which mandates deep investigation and improvement in engineering and technology appliances. Global energy consumption has grown in a century from the 1900s with only 1 TWh to an energy consumption of 17 TWh in 2011. As the world population grows faster, energy consumption has climbed by approximately 4-6 TWh. It is also expected to rise in the same trend in the upcoming years. Various researchers have tried to bring about new technologies that comply with energy conservation and environmentally friendly technologies to combat these issues. The improvement of heat transfer devices, such as shell and tube condensers, makes a substantial contribution to energy conservation, system performance efficiencies, and device compactness. A chiller unit is one of the devices found as a central component in air-conditioning systems, marine propulsion, process industries, and oil refineries. A shell-and-tube heat exchanger is a chiller unit employed for extracting heat energy from the vapor form of fluid, through which the vapor changes its phase into liquid form. Researchers have been developing different external surface structures to achieve augmented values of the coefficient of condensation heat transfer, such as two-dimensional and three-dimensional integral finned tubes, dimpled surfaces, petal-shaped fins, and serrated surfaces. In fact, unless optimal retrofit design considerations are taken on the augmented surface, structured tubes increase the pressure drop, which would cost extra pumping power and reduce the overall performance of the chiller unit. The advancements in manufacturing technology can help with the flexible development of three-dimensional fin profiles from the optimum two-dimensional finned tubes. However, condenser tubes with various three-dimensional surfaces, which exhibit superior enhancement factors in single condenser tests, have a stronger bundle effect in the full set condenser than the common two-dimensional integrally finned tubes. The continuous fins of integral fin tubes may operate as dams to avoid the axial diffusion of film condensate, which would explain the favorable row effect. Although increasing the active surface area for condensation heat transfer is the primary goal of low-finned integrated fin tubes, determining the ideal fin spacing for a particular refrigerant becomes crucial. Since the surface tension effect increases, the condensation heat transfer coefficient decreases as the fin spacing decreases. During film condensation over the outer surface, Fri, 01 Mar 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20431 2024-03-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/20430 Title: DESIGN, DEVELOPMENT AND CONTROL OF SNAKE ROBOT Authors: Bhandari, Garima Abstract: The rapid advancement in robotics, highlighting the significance of hyper redundant robots, paves the way for versatile and efficient systems capable of navigating through a multitude of environments. Snake robots, characterized by their extensive range of motion and adaptability, set the stage for our exploration into the realm of snake robots. Snake robots, with their unique serpentine design and locomotion abilities, are emerging as pivotal tools in this technological evolution. They are especially adept at maneuvering through confined spaces, tackling rough terrains, and adapting to diverse conditions, making them ideal for applications such as industrial inspections and search and rescue missions. Driven by this motivation, our thesis delves deeply into optimizing their dynamic behaviors and extending their functional capabilities. In the intricate landscape of snake robotics, this thesis embarks on a journey to decode and optimize their dynamic behaviors, leveraging the sophisticated flexible bond graph formalism. Central to our investigations is the introduction of a robust controller grounded in the fuzzy type 2 Takagi-Sugeno model, specifically engineered to harness and guide the snake robot’s natural lateral undulation gait. Progressing into the burgeoning domain of soft robotics, the research unveils a novel pneumatic actuator design, underpinned by a two-way air pump mechanism. This innovative approach heralds the development of an untethered soft snake robot, marking a potential paradigm shift in robotic exploration capabilities. Recognizing the challenges that soft actuators present, especially the detrimental leakage-related faults, thesis culminates with a meticulous analysis complemented with pragmatic reconfiguration strategies articulated to ensure the robot’s resilience and consistent performance. To cement the reliability and robustness of the methodologies and designs presented, the efficacy of the work undertaken has been validated through rigorous simulation and experimental results. This validation reinforces the thesis’s contributions and paves the way for future advancements in the field. Mon, 01 Jul 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20430 2024-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/20429 Title: MICROWAVE PROCESSING OF SUSTAINABLE NATURAL FIBER REINFORCED THERMOPLASTIC COMPOSITES Authors: Naik, Tejas Pramod Abstract: The role of materials is crucial for the development of human civilization. Polymer matrix composites (PMCs) are being used widely to fabricate various products in different industries: automotive, aerospace, construction and building materials, domestic (indoor and outdoor applications), electronics, etc. The commonly used reinforcement material in PMCs is fibers. When considering synthetic fibers, carbon, glass, and aramid fibers are extensively used among the available synthetic fibers. In the present scenario, researchers are concerned about ecological pressure, environment-friendly materials, and sustainable development. Therefore, the current focus is on fabricating PMCs reinforced with natural fibers. Natural fibers are proving to be the best candidates because of numerous benefits over synthetic fibers in terms of their renewability, low density, low cost, biodegradability, etc. Generally, fabrication processes for PMCs utilize different types of raw materials, including resins, fabrics, fillers, fibers, mats, and prepregs to manufacture composite products. The commonly used conventional fabrication processes for PMCs include compression molding, injection molding, vacuum bagging, spray-up, resin transfer molding, hand lay-up, pultrusion, and filament winding. Recently search for novel energy-efficient, eco-friendly, and time-saving manufacturing techniques has gained momentum due to environmental awareness and new rules and regulations laid down by governments worldwide. In this regard, microwave energy has attracted attention because it is a time/energy efficient, eco-friendly route for processing of PMCs. The reason behind using microwave energy to fabricate PMCs is its fast-heating rate, volumetric heating, and the products obtained have enhanced properties. Microwave curing technique has been employed to process thermoset-based composites since 1980; however, processing thermoplastic-based composites with natural fibers as reinforcement calls for additional information and investigation. The present research endeavour is divided into four broad areas, focusing on the processability of natural fiber-reinforced composites (NFRCs) using microwave energy, compatibility between fiber and matrix, friction and wear behavior, and environmental ageing behavior of the developed polymeric composite. Wed, 01 May 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20429 2024-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/20417 Title: EXPERIMENTAL INVESTIGATIONS INTO ULTRASONIC ASSISTED GRINDING OF DIFFICULT TO CUT MATERIALS WITH ULTRASONICALLY ATOMIZED GREEN SOLVENTS Authors: Singh, Aswani Kumar Abstract: Nickel-base superalloys are essential materials for manufacturing niche products like aircraft engines, gas, and steam turbine components. About 50% of aircraft engine components are fabricated from these materials because they have excellent mechanical properties in high temperatures. Due to their physical properties, such as strength and toughness at elevated temperatures, poor thermal conductivity, and high sensitivity to thermal damages, nickel-base superalloys are characterized as materials with extremely low grindability. As a result, several challenges are encountered during conventional mode of grinding in the form of environmental factors, worker health issues, surface integrity, material stability and incessant energy consumption during machining process. Besides this, the emissions from cutting fluids and their disposal are also a concern for the environment. In order to alleviate these problems associated with Conventional Grinding (CG), the present research attempt focused on modifying the mechanism of the grinding process by harnessing the dual advantages of Ultrasonic Assisted Grinding (UAG) and ultrasonically atomized novel green cutting fluid to achieve better performance and enhanced sustainability. In this regard, novel green Ionic Liquid (ILs) based cutting fluids have been developed to address machining processes' sustainability issues. ILs based cutting fluid resulted in enhanced thermophysical and tribological properties as compared to neat rice bran oil. Also, the prepared fluids are free from toxic materials, making them suitable for workers in the machining industries. ILs with Rice Bran Oil (RBO) can be used to mitigate excessive utilization of cutting fluids and emissions of various harmful gases that lead to a negative impact on the environment. Further, the LCA of prepared cutting fluids showed that they have a negligible adverse effect on the environment and are far superior to conventional lubricants. The investigations of cutting forces, Coefficient of Friction (CoF), surface integrity, and chip morphology have been done for different grinding approaches of Nimonic 80A. Then, based on the acquired data, a comparative study has been carried out to investigate the effect of ultrasonic vibration and atomized cutting fluid on the CG operation. A significant reduction in grinding forces by 66.22% and 52.66% for normal and tangential cutting force, respectively, and surface roughness by 46.48% has been observed during Ultrasonic Assisted Grinding with Ultrasonically Atomized Fluid (UaFUAG) as compared to the CG. Thu, 01 Feb 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/20417 2024-02-01T00:00:00Z