Analysis of Interfacial Processes on Non-Wetting Surfaces
| dc.contributor.author | Hatte, Sandeep Shankarrao | en |
| dc.contributor.committeechair | Pitchumani, Ranga | en |
| dc.contributor.committeemember | Davalos, Rafael V. | en |
| dc.contributor.committeemember | Cheng, Jiangtao | en |
| dc.contributor.committeemember | Mahajan, Roop L. | en |
| dc.contributor.department | Mechanical Engineering | en |
| dc.date.accessioned | 2022-10-05T08:00:13Z | en |
| dc.date.available | 2022-10-05T08:00:13Z | en |
| dc.date.issued | 2022-10-04 | en |
| dc.description.abstract | Non-wetting surfaces mainly categorized into superhydrophobic (SHS), lubricant-infused (LIS) and solid-infused surfaces (SIS), by virtue of their superior water repellant properties have wide applications in several energy and environmental systems. In this dissertation, the role of non-wetting surfaces toward the enhancement of condensation effectiveness is analyzed by taking into consideration the tube side and shell side individual interfacial energy transport processes namely, drag reduction, convection heat transfer enhancement, fouling mitigation and dropwise condensation heat transfer. First, an analytical solution is developed for effective slip length and, in turn, drag reduction and friction factor on structured non-wetting surfaces. Secondly, by combining the solution for effective slip length on structured non-wetting surfaces and the fractal characterization of generic multiscale rough surfaces, a theoretical analysis of drag reduction, friction factor, and convection heat transfer enhancement is conducted for scalable non-wetting surfaces. Next, fractal representation of rough surfaces is used to theoretical derive the dropwise condensation heat transfer performance on SHS and novel SIS surfaces. The aspect of dynamic fouling mitigation properties of non-wetting surfaces is explored by conducting systematic experiments. Using Taguchi design of experiments, this work for the first time presents a closed formed relationship of fouling mitigation quantified in terms of asymptotic fouling resistance with Reynolds number, foulant concentration and viscosity of the infusion material that represents the different surface types in a unified manner. Furthermore, it was observed that LIS and SIS offer excellent fouling mitigation compared to SHS and conventional smooth surfaces, however only SIS owing to the presence of solid-like infusion materials is observed to be robust for practical applications. | en |
| dc.description.abstractgeneral | Inspired by the naturally occurring water repellant lotus leaf and pitcher plant, metallic surfaces have undergone engineering modifications to their native wetting properties. By generating roughness features ranging from nanometer to micrometer length scales, subjecting them to low surface energy treatments and by choosing an appropriate water repellant infusion material, the water repellant properties seen on lotus leaf and pitcher plant can be engineered. Such water repellant (non-wetting) surface fabrication methods are widely available in the literature however very few are scalable to surface types (e.g. copper, aluminum etc.), surface size (millimeters to meters) and shape (plain, curved, inside of tubes etc.). In this work, considering scalable fabrication methods such as electrodeposition and chemical etching, a systematic analysis is conducted on enhancement of four interfacial processes that are a part of many industrial applications. First, the extent of water repellency by structured non-wetting surfaces for the flow of fluid (water) quantified in terms of effective slip length of flow is analytically derived. Using this theory and a self-similar (fractal) nature of the more generic rough surface designs, a theoretical analysis into the drag reduction, convection heat transfer enhancement on non-wetting surfaces is conducted. Next, using the fractal nature of the rough superhydrophobic surfaces (SHS) a theoretical investigation into dropwise condensation performance is used to derive bounds on condensation heat transfer enhancement. Through systematic experimental investigations, it is shown that a solid-infused surface (SIS) and lubricant-infused surfaces (LIS) which, respectively, incorporate a polymer and a slippery lubricant in the interstitial region of metallic asperities, exhibit superior dynamic mineral fouling mitigation performance compared to SHS and conventional smooth surfaces. In addition, it is demonstrated that SIS is a far robust and durable choice when compared to LIS for use in the long run. | en |
| dc.description.degree | Doctor of Philosophy | en |
| dc.format.medium | ETD | en |
| dc.identifier.other | vt_gsexam:35457 | en |
| dc.identifier.uri | http://hdl.handle.net/10919/112074 | en |
| dc.language.iso | en | en |
| dc.publisher | Virginia Tech | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject | Non-wetting surfaces | en |
| dc.subject | superhydrophobic surfaces | en |
| dc.subject | lubricant-infused surfaces | en |
| dc.subject | solid-infused surfaces | en |
| dc.subject | drag reduction | en |
| dc.subject | convection | en |
| dc.subject | condensation | en |
| dc.subject | fouling | en |
| dc.title | Analysis of Interfacial Processes on Non-Wetting Surfaces | en |
| dc.type | Dissertation | en |
| thesis.degree.discipline | Mechanical Engineering | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | doctoral | en |
| thesis.degree.name | Doctor of Philosophy | en |
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