78 research outputs found
Phase change phenomena on water repelling and biphilic surfaces
No full textThis Dissertation was approved for publication on 2019-04-10 at 09:54.Water-repelling surfaces have been studied for many decades. Hydrophobic and superhydrophobic surfaces are beneficial in phase change heat transfer applications, specifically during condensation because of the enhanced heat transfer and during freezing because of the anti-freezing properties. The current study is focused on enhanced phase change phenomena on superhydrophobic and biphilic surfaces. Hydrophobic surfaces that enable dropwise condensation exhibit 5-10X higher heat transfer. Coalescence induced droplet jumping on superhydrophobic surfaces further increases the heat transfer by 30%. Here, biphilic surfaces consisting of hydrophilic spots on a superhydrophobic background are studied for enhanced condensation. Water droplets nucleating at the hydrophilic spots grow to sizes defined by the biphilic geometry, followed by coalescence and departure. A high fidelity model that captures departure dynamics during droplet jumping on biphilic surfaces and predict the overall condensation heat transfer has been developed. By controlling the spatial geometry and length scale of the hydrophilic spots, enhanced (10X) jumping-droplet condensation heat transfer is obtained.
In terms of freezing and frost formation, understanding the mechanisms of frost formation is essential to a variety of Heating, Ventilating, Air Conditioning and Refrigeration (HVAC&R) applications. When water vapor in the ambient condenses on a chilled substrate in the form of liquid water and then freezes, it is known as condensation frosting. The dominant mechanism governing the spread of condensation frosting is inter-droplet ice bridge frost wave propagation. When a subcooled condensate water droplet freezes on a hydrophobic or superhydrophobic surface, neighboring droplets still in the liquid phase begin to evaporate. The evaporated water molecules deposit on the frozen droplet and initiate the growth of ice bridges directed toward the water droplets being depleted. Neighboring liquid droplets freeze as soon as the ice bridge connects. In this study, the significance of individual droplet freezing on frost wave propagation is studied. 10X slower frost wave propagation speeds on superhydrophobic surfaces are observed. Furthermore, at larger length scales, during bulk freezing of water, it has been shown that superhydrophobic surfaces offer no delay in freezing.
Although frosting delay has been shown with superhydrophobic surfaces, complete elimination of frosting has not been achieved. Given enough time, frosting will initiate and spread to cover the entire surface. In the HVAC&R sectors, the most common approach to remove frost from a surface (defrost) is to reverse the system cycle direction and heat the working fluid. However, water retention on the heat exchanger surface during defrosting decreases the long term heat transfer performance. In this study, the defrosting behavior of superhydrophobic and biphilic surfaces comprising of spatially distinct superhydrophobic and hydrophilic domains is used to accelerate defrosting. During defrosting, biphilic surfaces are shown to exhibit enhanced surface cleaning with no water retention. Furthermore, an ultra-efficient method to defrost a surface covered with ice/frost by focusing energy at the substrate-ice interface is studied. To remove ice/frost efficiently, only the interfacial layer adhering the ice/frost to the solid surface is melted by using a localized ‘pulse’ of heat, allowing gravity or gas shear in conjunction with the ultra-thin lubricating melt water layer to remove the ice/frost. A high fidelity numerical model is developed to simulate pulse defrosting. This work not only provides a fundamental understanding of phase change processes on superhydrophobic and biphilic surfaces, but also elucidates its applications for a plethora of energy industries.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Shreyas Chavan, accepted the attached license on 2019-04-09 at 16:13.The student, Shreyas Chavan, submitted this Dissertation for approval on 2019-04-09 at 16:16.DSpace SAF Submission Ingestion Package generated from Vireo submission #13540 on 2019-08-22 at 16:20:55Made available in DSpace on 2019-08-23T20:44:41Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-04-10Embargo set by: Seth Robbins for item 112291
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Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112291
Lift date: 2021-08-23T20:46:41Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112291
Lift date: 2021-08-23T20:47:38Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112291
Lift date: 2021-08-23T20:48:32Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 112291 on 2021-08-24T09:15:24Z
Linking Dynamic Absorptive Capacity and Service Innovation for Born Global Service Firms: An Organization Innovation Lens Perspective
No full textGrounded in the dynamic capabilities approach and organizational sub-system view on internationalization, this quantitative study develops and empirically tests a model of international market performance of born global service firms. While several scholars highlighted innovativeness as a driver of competitiveness for born global firms, the capacities underlying the born global firm's innovativeness have received limited scholarly attention, specifically, dynamic absorptive capacities (exploratory, transformative, and exploitative learning capacities). The uniqueness of this paper posits that dynamic absorptive capacities in a born global service firm have contributed to innovation and resulted in international market outcomes. The data was collected using the survey method from born global service firms and was analyzed using structured equation modeling. The findings of this study reveal that service innovation and business strategy are critical drivers of international performance for born global service firms. The paper contributes to the literature on the significance of absorptive capacity in born global service firms by identifying those dynamic absorptive capacities that operate in a composite set of relationships with other capabilities and significantly contribute to their innovation, impacting their internationalization outcomes. This study also supplements the theoretical and practical implications derived from the key findings of this study and provides future research directions
Interfacing of Wind Energy to Grid using Static Compensator and Load Reactive Power Compensation
No full textInterfacing of hybrid power system to grid using statcom & power quality improvement
No full textSymmetry transition via tetravalent impurity and investigations on magnetic properties of Li0.5Fe2.5O4
No full textExtra- cellular Pectinase Activity of Post-harvest Fungi from Papaya Fruits in Presence of Different Influencing Factors
No full textThe present paper deals with the study of pectinase enzyme activity of post-harvest fungi of papaya fruits under the influence of nutritional factors, antibiotics, vitamins and fungicides. It was found that carboxy methyl cellulose (CMC), sodium sulphate; ferrous sulphate, barium chloride, sodium chloride, magnesium chloride, zinc, ferrous, manganese, copper, barium, fungicides and ampicillin inhibits the pectinase action of all tested post-harvest fungi while other factors induces the same. --------------------------------------------------------------------------------------------------------1Dept. of Botany, Shrikrishna Mahavidyalaya, Gunjoti, Dist Osmanabad, Aurangabad; 2Seed pathology and Fungal Biotechnology Laboratory, Dept. of Botany, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad- 431 004. (M.S.) India.* Corresponding Author, Email: [email protected] Please Cite This Article As: G.M. Rathod and Ashok M. Chavan. 2010. Extra- cellular Pectinase Activity of Post-harvest Fungi from Papaya Fruits in Presence of Different Influencing Factors. J. Exp. Sci. 1(2): 07-11
Using STATCOM interfacing of renewable energy source to grid and power quality improvement
No full textPESI - a taxonomic backbone for Europe
No full textThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The attached file is the published version of the article.NHM Repositor
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