{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/99161"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/99161","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Heat transfer enhancement phenomena and pressure drop characteristics in two-phase pulsating flow using R-134A","abstract":"The heat transfer and pressure drop aspect of a saturated two-phase flow imposed to periodic inlet mass flow rate were studied using both experimental and modeling approaches. The two-phase flow of R-134 was tested in a single pass, horizontal smooth copper tube coil with a 6.2 mm (0.244-in.) inner diameter. The test section uses aluminum plain fins 0.30 m (11.8-in.) long, 0.03 m (1.18-in.) wide and 0.3 mm (0.012-in.) thick. Heat was applied to the test section using external air flow at ambient temperature. The test parameters varied as follows: mass flux, 75 – 250 kg/m2-s (55 – 184 klbm/ft2-hr); heat flux, 2-12 kW/m2 (600-3800 Btu/hr-ft2); vapor quality, 10-98 percent; saturation temperature 15 oC (59 oF); flow pulsation period (2-24 sec). The temporal pressure drop data was recorded and used as the basis of a newly proposed close-form model for predicting the heat transfer and pressure drop for pulsating two-phase flow based on the quasi-steady state assumption. The enhancement of heat transfer in saturated boiling pulsating two-phase flow was found to be higher in shorter pulsation periods. It was also found that for low inlet vapor qualities and short pulsation periods, reduction in the pressure drop and enhancement in heat transfer coefficient could be achieved at the same time, which can be potentially beneficial to the system COP. Furthermore, the flow regime, which is a widely recognized factor having dominant influence on the heat transfer of two-phase flow, was also captured and analyzed in this study using high speed camera. Synchronized flow regime images and pressure drop data were also presented to demonstrate the relation between flow regime evolution and pressure drop variation with time as a potential means to identify the flow regime using the pressure drop characteristics.","abstract_html":"The heat transfer and pressure drop aspect of a saturated two-phase flow imposed to periodic inlet mass flow rate were studied using both experimental and modeling approaches. The two-phase flow of R-134 was tested in a single pass, horizontal smooth copper tube coil with a 6.2 mm (0.244-in.) inner diameter. The test section uses aluminum plain fins 0.30 m (11.8-in.) long, 0.03 m (1.18-in.) wide and 0.3 mm (0.012-in.) thick. Heat was applied to the test section using external air flow at ambient temperature. The test parameters varied as follows: mass flux, 75 – 250 kg/m2-s (55 – 184 klbm/ft2-hr); heat flux, 2-12 kW/m2 (600-3800 Btu/hr-ft2); vapor quality, 10-98 percent; saturation temperature 15 oC (59 oF); flow pulsation period (2-24 sec). The temporal pressure drop data was recorded and used as the basis of a newly proposed close-form model for predicting the heat transfer and pressure drop for pulsating two-phase flow based on the quasi-steady state assumption. The enhancement of heat transfer in saturated boiling pulsating two-phase flow was found to be higher in shorter pulsation periods. It was also found that for low inlet vapor qualities and short pulsation periods, reduction in the pressure drop and enhancement in heat transfer coefficient could be achieved at the same time, which can be potentially beneficial to the system COP. Furthermore, the flow regime, which is a widely recognized factor having dominant influence on the heat transfer of two-phase flow, was also captured and analyzed in this study using high speed camera. Synchronized flow regime images and pressure drop data were also presented to demonstrate the relation between flow regime evolution and pressure drop variation with time as a potential means to identify the flow regime using the pressure drop characteristics.","abstract_has_math":false,"creators":["Zhang, Yuheng"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Wang, Xiaofei"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-03-13T15:20:48Z","date_published":"2018-03-13T15:20:48Z","updated_at":"2026-07-22T22:24:37Z","subjects":["Pulsating","Pulsatile","Pulsed","Two phase flow","Heat transfer","Pressure drop","Flow boiling","Experiment","Model"],"languages":["en"],"rights":["Copyright 2017 Yuheng Zhang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/99161","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Wang, Xiaofei"]},{"key":"dc:creator","label":"Author","values":["Zhang, Yuheng"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-03-13T15:20:48Z","2020-03-14T09:15:22Z","2017-12-14","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":["Pulsating","Pulsatile","Pulsed","Two phase flow","Heat transfer","Pressure drop","Flow boiling","Experiment","Model"]}]},{"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 Yuheng Zhang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/99161"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The heat transfer and pressure drop aspect of a saturated two-phase flow imposed to periodic inlet mass flow rate were studied using both experimental and modeling approaches. The two-phase flow of R-134 was tested in a single pass, horizontal smooth copper tube coil with a 6.2 mm (0.244-in.) inner diameter. The test section uses aluminum plain fins 0.30 m (11.8-in.) long, 0.03 m (1.18-in.) wide and 0.3 mm (0.012-in.) thick. Heat was applied to the test section using external air flow at ambient temperature. The test parameters varied as follows: mass flux, 75 – 250 kg/m2-s (55 – 184 klbm/ft2-hr); heat flux, 2-12 kW/m2 (600-3800 Btu/hr-ft2); vapor quality, 10-98 percent; saturation temperature 15 oC (59 oF); flow pulsation period (2-24 sec). The temporal pressure drop data was recorded and used as the basis of a newly proposed close-form model for predicting the heat transfer and pressure drop for pulsating two-phase flow based on the quasi-steady state assumption. The enhancement of heat transfer in saturated boiling pulsating two-phase flow was found to be higher in shorter pulsation periods. It was also found that for low inlet vapor qualities and short pulsation periods, reduction in the pressure drop and enhancement in heat transfer coefficient could be achieved at the same time, which can be potentially beneficial to the system COP. Furthermore, the flow regime, which is a widely recognized factor having dominant influence on the heat transfer of two-phase flow, was also captured and analyzed in this study using high speed camera. Synchronized flow regime images and pressure drop data were also presented to demonstrate the relation between flow regime evolution and pressure drop variation with time as a potential means to identify the flow regime using the pressure drop characteristics.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-12-01","The student, Yuheng Zhang, accepted the attached license on 2017-12-13 at 08:49.","The student, Yuheng Zhang, submitted this Thesis for approval on 2017-12-13 at 08:52.","This Thesis was approved for publication on 2017-12-14 at 10:48.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11211 on 2018-03-13 at 09:54:06","Made available in DSpace on 2018-03-13T15:20:48Z (GMT). No. of bitstreams: 2 ZHANG-THESIS-2017.pdf: 2807618 bytes, checksum: eef51df7795d291b9d1fb3c84d739d59 (MD5) LICENSE.txt: 4209 bytes, checksum: 3625659fc32aeb0b1e3450e0c0244d81 (MD5) Previous issue date: 2017-12-14","Embargo set by: Seth Robbins for item 105123 Lift date: 2020-03-13T15:21:19Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 105123 Lift date: 2020-03-13T15:25:40Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 105123 Lift date: 2020-03-13T15:28:52Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 105123 on 2020-03-14T09:15:22Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Heat transfer enhancement phenomena and pressure drop characteristics in two-phase pulsating flow using R-134A"]}]}],"canonical_facts":{"dc:contributor":["Wang, Xiaofei"],"dc:creator":["Zhang, Yuheng"],"dc:date":["2018-03-13T15:20:48Z","2020-03-14T09:15:22Z","2017-12-14","2017-12"],"dc:description":["The heat transfer and pressure drop aspect of a saturated two-phase flow imposed to periodic inlet mass flow rate were studied using both experimental and modeling approaches. The two-phase flow of R-134 was tested in a single pass, horizontal smooth copper tube coil with a 6.2 mm (0.244-in.) inner diameter. The test section uses aluminum plain fins 0.30 m (11.8-in.) long, 0.03 m (1.18-in.) wide and 0.3 mm (0.012-in.) thick. Heat was applied to the test section using external air flow at ambient temperature. The test parameters varied as follows: mass flux, 75 – 250 kg/m2-s (55 – 184 klbm/ft2-hr); heat flux, 2-12 kW/m2 (600-3800 Btu/hr-ft2); vapor quality, 10-98 percent; saturation temperature 15 oC (59 oF); flow pulsation period (2-24 sec). The temporal pressure drop data was recorded and used as the basis of a newly proposed close-form model for predicting the heat transfer and pressure drop for pulsating two-phase flow based on the quasi-steady state assumption. The enhancement of heat transfer in saturated boiling pulsating two-phase flow was found to be higher in shorter pulsation periods. It was also found that for low inlet vapor qualities and short pulsation periods, reduction in the pressure drop and enhancement in heat transfer coefficient could be achieved at the same time, which can be potentially beneficial to the system COP. Furthermore, the flow regime, which is a widely recognized factor having dominant influence on the heat transfer of two-phase flow, was also captured and analyzed in this study using high speed camera. Synchronized flow regime images and pressure drop data were also presented to demonstrate the relation between flow regime evolution and pressure drop variation with time as a potential means to identify the flow regime using the pressure drop characteristics.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-12-01","The student, Yuheng Zhang, accepted the attached license on 2017-12-13 at 08:49.","The student, Yuheng Zhang, submitted this Thesis for approval on 2017-12-13 at 08:52.","This Thesis was approved for publication on 2017-12-14 at 10:48.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11211 on 2018-03-13 at 09:54:06","Made available in DSpace on 2018-03-13T15:20:48Z (GMT). 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