{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/99348"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/99348","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Experimental investigation of variability between nucleation sites in flow boiling","abstract":"This Thesis was approved for publication on 2017-12-04 at 12:43.","abstract_html":"This Thesis was approved for publication on 2017-12-04 at 12:43.","abstract_has_math":false,"creators":["Ooi, Zhiee Jhia"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Nuclear, Plasma, Radiolgc Engr","degree_department":null,"school":null,"contributors":["Brooks, Caleb Stephen","Kozlowski, Tomasz"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-03-13T15:48:45Z","date_published":"2018-03-13T15:48:45Z","updated_at":"2026-07-22T22:24:37Z","subjects":["Subcooled boiling","Departure diameter","Departure frequency","Wall nucleation","Active nucleation site density"],"languages":["en"],"rights":["Copyright 2017 Zhiee Jhia Ooi"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/99348","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Brooks, Caleb Stephen","Kozlowski, Tomasz"]},{"key":"dc:creator","label":"Author","values":["Ooi, Zhiee Jhia"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-03-13T15:48:45Z","2017-12-04","2017-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear, Plasma, Radiolgc Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["Subcooled boiling","Departure diameter","Departure frequency","Wall nucleation","Active nucleation site density"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2017 Zhiee Jhia Ooi"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/99348"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This Thesis was approved for publication on 2017-12-04 at 12:43.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11789 on 2018-03-13 at 10:09:31","Wall nucleation characteristics are studied in terms of the bubble departure diameter and frequency in order to improve the prediction of bubble production and release in subcooled boiling flow. In the past, departure diameter and frequency models are shown to exhibit a wide range of accuracy depending on the experimental conditions. The variability of bubble departure diameter and frequency in an experimental condition is investigated in an effort to determine the possible causes behind the poor accuracy of existing wall nucleation characteristic models. Subcooled boiling flow experiments have been conducted in a vertical square channel where bubble departures from multiple sites are recorded and measured simultaneously with a high-speed camera for ten conditions. Existing bubble departure diameter models are benchmarked and are shown to be satisfactory in predicting condition-average bubble departure diameter. The probability density functions (PDF) of bubble departure diameters are observed to be normal at medium and elevated pressure but positive-skewed at low pressure. A skewed distribution suggests that the number mean bubble diameter (the sum of all departure diameters measured at an active nucleation site divided by the number of departures measured) is different from the surface area and volume mean diameters. Hence, the number mean diameter needs to be corrected with the distribution factors to ensure the accuracy of volume and surface area modeling. On the other hand, significant variations are observed in the bubble departure frequency across different nucleation sites of a given experimental condition largely due to intermittent periods of inactivity. A benchmark of the existing bubble departure frequency models shows that the models are generally applicable to an ‘active’ frequency but cannot account for the impact of these periods of inactivity. This finding highlights an important issue in the current modeling and understanding of the gas-phase boundary condition. This periodic inactivity, if not incorporated into the wall nucleation modeling, will result in a large overprediction of bubbles generated at the wall. A physical justification for this inactivity is discussed based on the modeling of the active nucleation site density which is observed to fluctuate strongly according to wall superheat. As the departure frequencies of multiple sites are considered, a new method to determine the condition-average departure frequency is proposed.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-03-13 without embargo terms","The student, Zhiee Jhia Ooi, accepted the attached license on 2017-12-04 at 09:03.","The student, Zhiee Jhia Ooi, submitted this Thesis for approval on 2017-12-04 at 09:11.","Made available in DSpace on 2018-03-13T15:48:45Z (GMT). No. of bitstreams: 2 OOI-THESIS-2017.pdf: 3706526 bytes, checksum: 77f7dcbd9b79239977ea4d02e0042d4a (MD5) LICENSE.txt: 4211 bytes, checksum: 816646b6a4e69e4fd06adf56cd32f2a0 (MD5) Previous issue date: 2017-12-04"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Experimental investigation of variability between nucleation sites in flow boiling"]}]}],"canonical_facts":{"dc:contributor":["Brooks, Caleb Stephen","Kozlowski, Tomasz"],"dc:creator":["Ooi, Zhiee Jhia"],"dc:date":["2018-03-13T15:48:45Z","2017-12-04","2017-12"],"dc:description":["This Thesis was approved for publication on 2017-12-04 at 12:43.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11789 on 2018-03-13 at 10:09:31","Wall nucleation characteristics are studied in terms of the bubble departure diameter and frequency in order to improve the prediction of bubble production and release in subcooled boiling flow. In the past, departure diameter and frequency models are shown to exhibit a wide range of accuracy depending on the experimental conditions. The variability of bubble departure diameter and frequency in an experimental condition is investigated in an effort to determine the possible causes behind the poor accuracy of existing wall nucleation characteristic models. Subcooled boiling flow experiments have been conducted in a vertical square channel where bubble departures from multiple sites are recorded and measured simultaneously with a high-speed camera for ten conditions. Existing bubble departure diameter models are benchmarked and are shown to be satisfactory in predicting condition-average bubble departure diameter. The probability density functions (PDF) of bubble departure diameters are observed to be normal at medium and elevated pressure but positive-skewed at low pressure. A skewed distribution suggests that the number mean bubble diameter (the sum of all departure diameters measured at an active nucleation site divided by the number of departures measured) is different from the surface area and volume mean diameters. Hence, the number mean diameter needs to be corrected with the distribution factors to ensure the accuracy of volume and surface area modeling. On the other hand, significant variations are observed in the bubble departure frequency across different nucleation sites of a given experimental condition largely due to intermittent periods of inactivity. A benchmark of the existing bubble departure frequency models shows that the models are generally applicable to an ‘active’ frequency but cannot account for the impact of these periods of inactivity. This finding highlights an important issue in the current modeling and understanding of the gas-phase boundary condition. This periodic inactivity, if not incorporated into the wall nucleation modeling, will result in a large overprediction of bubbles generated at the wall. A physical justification for this inactivity is discussed based on the modeling of the active nucleation site density which is observed to fluctuate strongly according to wall superheat. As the departure frequencies of multiple sites are considered, a new method to determine the condition-average departure frequency is proposed.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-03-13 without embargo terms","The student, Zhiee Jhia Ooi, accepted the attached license on 2017-12-04 at 09:03.","The student, Zhiee Jhia Ooi, submitted this Thesis for approval on 2017-12-04 at 09:11.","Made available in DSpace on 2018-03-13T15:48:45Z (GMT). No. of bitstreams: 2 OOI-THESIS-2017.pdf: 3706526 bytes, checksum: 77f7dcbd9b79239977ea4d02e0042d4a (MD5) LICENSE.txt: 4211 bytes, checksum: 816646b6a4e69e4fd06adf56cd32f2a0 (MD5) Previous issue date: 2017-12-04"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/99348"],"dc:language":["en"],"dc:rights":["Copyright 2017 Zhiee Jhia Ooi"],"dc:subject":["Subcooled boiling","Departure diameter","Departure frequency","Wall nucleation","Active nucleation site density"],"dc:title":["Experimental investigation of variability between nucleation sites in flow boiling"],"dc:type":["text"],"thesis:degree_discipline":["Nuclear, Plasma, Radiolgc Engr"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:37Z"}