{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/99367"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/99367","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Development of capacitive sensor to determine void fraction in horizontal and vertical tubes","abstract":"This study first presents flow regimes and void fraction in horizontal and vertical tubes with R134a in the adiabatic condition and low mass flux range. Visualization results of horizontal flow patterns are compared to Wojtan-Ursenbacher-Thome flow regime map and have a good agreement. Both void fraction results for horizontal and vertical tubes are compared to some widely used correlations. Influences of tube orientation and mass flux on void fraction are discussed. At the same vapor quality condition, void fraction of horizontal tubes is larger than that of vertical tubes. Higher mass flux also results in larger void fraction compared that of lower mass flux. A new capacitive sensor aimed to measure void fraction is designed and built. With this capacitive sensor, characterizing flow patterns appear in low mass flux range and measuring void fraction for horizontal and vertical tubes can be achieved. Signal characterization for each flow pattern is proposed. To apply this sensor to more applications in HVAC&R systems, electrodes with different axial lengths are built together to be compared. The comparison of signals from them show the signals are independent on axial length. Due to the non-uniformity of the electric field between the electrodes of the sensor, a calibration procedure of void fraction measurement must be finished before utilizations. An experiment based (quick closing valves (QCV)) calibration procedure is conducted. Two calibrated curves for measuring void fraction in horizontal and vertical tubes are proposed. With calibrated curves, sensors with similar configurations can be directly utilized to measure void fraction in further studies.","abstract_html":"This study first presents flow regimes and void fraction in horizontal and vertical tubes with R134a in the adiabatic condition and low mass flux range. Visualization results of horizontal flow patterns are compared to Wojtan-Ursenbacher-Thome flow regime map and have a good agreement. Both void fraction results for horizontal and vertical tubes are compared to some widely used correlations. Influences of tube orientation and mass flux on void fraction are discussed. At the same vapor quality condition, void fraction of horizontal tubes is larger than that of vertical tubes. Higher mass flux also results in larger void fraction compared that of lower mass flux. A new capacitive sensor aimed to measure void fraction is designed and built. With this capacitive sensor, characterizing flow patterns appear in low mass flux range and measuring void fraction for horizontal and vertical tubes can be achieved. Signal characterization for each flow pattern is proposed. To apply this sensor to more applications in HVAC&R systems, electrodes with different axial lengths are built together to be compared. The comparison of signals from them show the signals are independent on axial length. Due to the non-uniformity of the electric field between the electrodes of the sensor, a calibration procedure of void fraction measurement must be finished before utilizations. An experiment based (quick closing valves (QCV)) calibration procedure is conducted. Two calibrated curves for measuring void fraction in horizontal and vertical tubes are proposed. With calibrated curves, sensors with similar configurations can be directly utilized to measure void fraction in further studies.","abstract_has_math":false,"creators":["Qian, Hongliang"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Hrnjak, Predrag"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-03-13T15:48:54Z","date_published":"2018-03-13T15:48:54Z","updated_at":"2026-07-22T22:24:37Z","subjects":["Void fraction","Flow regimes","Round tubes","Quick closing valves","Capacitance sensor"],"languages":["en"],"rights":["Copyright 2017 Hongliang Qian"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/99367","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hrnjak, Predrag"]},{"key":"dc:creator","label":"Author","values":["Qian, Hongliang"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-03-13T15:48:54Z","2017-12-05","2017-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"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":["Void fraction","Flow regimes","Round tubes","Quick closing valves","Capacitance sensor"]}]},{"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 Hongliang Qian"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/99367"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This study first presents flow regimes and void fraction in horizontal and vertical tubes with R134a in the adiabatic condition and low mass flux range. Visualization results of horizontal flow patterns are compared to Wojtan-Ursenbacher-Thome flow regime map and have a good agreement. Both void fraction results for horizontal and vertical tubes are compared to some widely used correlations. Influences of tube orientation and mass flux on void fraction are discussed. At the same vapor quality condition, void fraction of horizontal tubes is larger than that of vertical tubes. Higher mass flux also results in larger void fraction compared that of lower mass flux. A new capacitive sensor aimed to measure void fraction is designed and built. With this capacitive sensor, characterizing flow patterns appear in low mass flux range and measuring void fraction for horizontal and vertical tubes can be achieved. Signal characterization for each flow pattern is proposed. To apply this sensor to more applications in HVAC&R systems, electrodes with different axial lengths are built together to be compared. The comparison of signals from them show the signals are independent on axial length. Due to the non-uniformity of the electric field between the electrodes of the sensor, a calibration procedure of void fraction measurement must be finished before utilizations. An experiment based (quick closing valves (QCV)) calibration procedure is conducted. Two calibrated curves for measuring void fraction in horizontal and vertical tubes are proposed. With calibrated curves, sensors with similar configurations can be directly utilized to measure void fraction in further studies.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-03-13 without embargo terms","The student, Hongliang Qian, accepted the attached license on 2017-12-04 at 19:45.","The student, Hongliang Qian, submitted this Thesis for approval on 2017-12-04 at 19:59.","This Thesis was approved for publication on 2017-12-05 at 14:27.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11844 on 2018-03-13 at 10:10:33","Made available in DSpace on 2018-03-13T15:48:54Z (GMT). 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Influences of tube orientation and mass flux on void fraction are discussed. At the same vapor quality condition, void fraction of horizontal tubes is larger than that of vertical tubes. Higher mass flux also results in larger void fraction compared that of lower mass flux. A new capacitive sensor aimed to measure void fraction is designed and built. With this capacitive sensor, characterizing flow patterns appear in low mass flux range and measuring void fraction for horizontal and vertical tubes can be achieved. Signal characterization for each flow pattern is proposed. To apply this sensor to more applications in HVAC&R systems, electrodes with different axial lengths are built together to be compared. The comparison of signals from them show the signals are independent on axial length. Due to the non-uniformity of the electric field between the electrodes of the sensor, a calibration procedure of void fraction measurement must be finished before utilizations. An experiment based (quick closing valves (QCV)) calibration procedure is conducted. Two calibrated curves for measuring void fraction in horizontal and vertical tubes are proposed. With calibrated curves, sensors with similar configurations can be directly utilized to measure void fraction in further studies.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-03-13 without embargo terms","The student, Hongliang Qian, accepted the attached license on 2017-12-04 at 19:45.","The student, Hongliang Qian, submitted this Thesis for approval on 2017-12-04 at 19:59.","This Thesis was approved for publication on 2017-12-05 at 14:27.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11844 on 2018-03-13 at 10:10:33","Made available in DSpace on 2018-03-13T15:48:54Z (GMT). No. of bitstreams: 2 QIAN-THESIS-2017.pdf: 10770816 bytes, checksum: 9c13cac8a6ad09e2993a7eb4a37390d2 (MD5) LICENSE.txt: 4211 bytes, checksum: f7167a1d530d88406742519d459e0dd8 (MD5) Previous issue date: 2017-12-05"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/99367"],"dc:language":["en"],"dc:rights":["Copyright 2017 Hongliang Qian"],"dc:subject":["Void fraction","Flow regimes","Round tubes","Quick closing valves","Capacitance sensor"],"dc:title":["Development of capacitive sensor to determine void fraction in horizontal and vertical tubes"],"dc:type":["text"],"thesis:degree_discipline":["Mechanical Engineering"],"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"}