{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/115906"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/115906","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Structured surfaces at the extremes of heat transfer","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","abstract_has_math":false,"creators":["Boyina, Kalyan"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Miljkovic, Nenad","Wang, Sophie","Ferreira, Placid","Elbel, Stefan","Cosby, Ron"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-08","date_published":"2022-08","updated_at":"2026-07-22T22:24:55Z","subjects":["Heat Transfer","Phase-change","HVAC&R","Heat Pumps","Air cycle Machines","Heat exchangers","Polymer coatings","Nanostructures","Brazing."],"languages":["en","eng"],"rights":["Copyright 2022 Kalyan Boyina"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/115906","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Miljkovic, Nenad","Wang, Sophie","Ferreira, Placid","Elbel, Stefan","Cosby, Ron"]},{"key":"dc:creator","label":"Author","values":["Boyina, Kalyan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-08","2022-07-14"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Heat Transfer","Phase-change","HVAC&R","Heat Pumps","Air cycle Machines","Heat exchangers","Polymer coatings","Nanostructures","Brazing."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2022 Kalyan Boyina"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/115906"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","The student, Kalyan Boyina, accepted the attached license on 2022-07-09 at 22:06.","The student, Kalyan Boyina, submitted this Dissertation for approval on 2022-07-09 at 22:06.","This Dissertation was approved for publication on 2022-07-14 at 07:33.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18201 on 2022-11-16 at 10:18:10","The formation of frost on aluminum heat exchangers imposes severe penalties on various heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems by increasing thermal resistance and pressure drop. Decreased system efficiency leads to an increase in energy usage. Incomplete and inefficient braze alloy flow decreases the strength of brazed joints in various HVAC&R systems causing refrigerant leakage. Refrigerant leakage caused a direct increase in the global warming potential and an indirect increase in energy usage. These issues are tackled using specially designed structured surfaces that allow us to control phase change phenomena and fluid flow. This thesis focuses on developing scalable and feasible surface modifications for large-scale industrial systems. We begin by developing and applying a scalable superhydrophobic coating to off-the-shelf aluminum heat exchangers and testing their performance in various conditions. We specifically utilize the phenomenon of jumping droplet condensation to extend the frosting cycle and the low surface wettability to improve defrost efficiency. We then develop a simple and highly scalable surface modification to improve brazing alloy flow in copper to copper braze joints by increasing the wettability of the joints. The techniques and insights presented in this thesis improve the technology readiness level of superhydrophobic coatings and potentially decrease refrigerant leak rates from HVAC&R equipment. The discussion presented in this thesis will also inform future work on developing practical and durable coatings for different types of heat exchangers and how to evaluate them."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Structured surfaces at the extremes of heat transfer"]}]}],"canonical_facts":{"dc:contributor":["Miljkovic, Nenad","Wang, Sophie","Ferreira, Placid","Elbel, Stefan","Cosby, Ron"],"dc:creator":["Boyina, Kalyan"],"dc:date":["2022-08","2022-07-14"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","The student, Kalyan Boyina, accepted the attached license on 2022-07-09 at 22:06.","The student, Kalyan Boyina, submitted this Dissertation for approval on 2022-07-09 at 22:06.","This Dissertation was approved for publication on 2022-07-14 at 07:33.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18201 on 2022-11-16 at 10:18:10","The formation of frost on aluminum heat exchangers imposes severe penalties on various heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems by increasing thermal resistance and pressure drop. Decreased system efficiency leads to an increase in energy usage. Incomplete and inefficient braze alloy flow decreases the strength of brazed joints in various HVAC&R systems causing refrigerant leakage. Refrigerant leakage caused a direct increase in the global warming potential and an indirect increase in energy usage. These issues are tackled using specially designed structured surfaces that allow us to control phase change phenomena and fluid flow. This thesis focuses on developing scalable and feasible surface modifications for large-scale industrial systems. We begin by developing and applying a scalable superhydrophobic coating to off-the-shelf aluminum heat exchangers and testing their performance in various conditions. We specifically utilize the phenomenon of jumping droplet condensation to extend the frosting cycle and the low surface wettability to improve defrost efficiency. We then develop a simple and highly scalable surface modification to improve brazing alloy flow in copper to copper braze joints by increasing the wettability of the joints. The techniques and insights presented in this thesis improve the technology readiness level of superhydrophobic coatings and potentially decrease refrigerant leak rates from HVAC&R equipment. The discussion presented in this thesis will also inform future work on developing practical and durable coatings for different types of heat exchangers and how to evaluate them."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/115906"],"dc:language":["en","eng"],"dc:rights":["Copyright 2022 Kalyan Boyina"],"dc:subject":["Heat Transfer","Phase-change","HVAC&R","Heat Pumps","Air cycle Machines","Heat exchangers","Polymer coatings","Nanostructures","Brazing."],"dc:title":["Structured surfaces at the extremes of heat transfer"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:55Z"}