{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/101255"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/101255","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Radiative impacts on water mist/cloud droplet condensative growth","abstract":"The effect of thermal radiation on cloud droplet evolution was investigated both experimentally and theoretically. Droplet size measurements were conducted on laminar, saturated water mist flowing through a tube apparatus with an inner wall cooled to induce radiative heat transfer from the mist droplets to the tube wall. The flow tube was designed to isolate the radiative effect by eliminating convective heat transfer between the mist flow and the chamber wall. Droplet size distributions were measured before and after radiative cooling using a light scattering optical analyzer. Radiative flux varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section varied from 15 to 60 seconds. Droplet sizes increased significantly after they underwent radiative cooling. For example, with 145 W/m2 radiative flux, the volume-average size (D43) increased from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section. Thus, experimental evidence was obtained that demonstrated that droplet radiation to a remote, cold radiative sink can augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime. The droplet size distributions measured were fit with Weibull, Gaussian, and Lorentzian distribution functions, and the Gaussian distribution fit best. The results demonstrated that the radiatively induced condensation process transformed droplet spectra from monomodal to bimodal, in accordance with theoretical predictions. These bimodal droplet distributions were found to be skewed positively, with relatively wide dispersions for the smaller mode and less dispersion for the larger mode. Theoretical results were compared with droplet size distributions measured before and after radiative cooling, for radiative flux that varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section that ranged from 15 to 60 seconds. Calculations confirmed the experimental observations that droplet sizes increased significantly after experiencing radiative cooling. For example, with 145 W/m2 radiative flux (245 K wall temperature), calculations predicted a volume-average size (D43) increase from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section, which was consistent with measurements. With respect to size distribution data, calculations showed partial or qualitative agreement, but not complete quantitative agreement, in that the calculations matched the experimental size distribution data reasonably well only for droplets larger than 100 µm, indicating the need for further improvement in modeling assumptions. Thus, theoretical support was demonstrated for the concept that droplet radiation to a remote, cold radiative sink might augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime.","abstract_html":"The effect of thermal radiation on cloud droplet evolution was investigated both experimentally and theoretically. Droplet size measurements were conducted on laminar, saturated water mist flowing through a tube apparatus with an inner wall cooled to induce radiative heat transfer from the mist droplets to the tube wall. The flow tube was designed to isolate the radiative effect by eliminating convective heat transfer between the mist flow and the chamber wall. Droplet size distributions were measured before and after radiative cooling using a light scattering optical analyzer. Radiative flux varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section varied from 15 to 60 seconds. Droplet sizes increased significantly after they underwent radiative cooling. For example, with 145 W/m2 radiative flux, the volume-average size (D43) increased from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section. Thus, experimental evidence was obtained that demonstrated that droplet radiation to a remote, cold radiative sink can augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime. The droplet size distributions measured were fit with Weibull, Gaussian, and Lorentzian distribution functions, and the Gaussian distribution fit best. The results demonstrated that the radiatively induced condensation process transformed droplet spectra from monomodal to bimodal, in accordance with theoretical predictions. These bimodal droplet distributions were found to be skewed positively, with relatively wide dispersions for the smaller mode and less dispersion for the larger mode. Theoretical results were compared with droplet size distributions measured before and after radiative cooling, for radiative flux that varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section that ranged from 15 to 60 seconds. Calculations confirmed the experimental observations that droplet sizes increased significantly after experiencing radiative cooling. For example, with 145 W/m2 radiative flux (245 K wall temperature), calculations predicted a volume-average size (D43) increase from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section, which was consistent with measurements. With respect to size distribution data, calculations showed partial or qualitative agreement, but not complete quantitative agreement, in that the calculations matched the experimental size distribution data reasonably well only for droplets larger than 100 µm, indicating the need for further improvement in modeling assumptions. Thus, theoretical support was demonstrated for the concept that droplet radiation to a remote, cold radiative sink might augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime.","abstract_has_math":false,"creators":["Roman, Kibria Khan"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Brewster, M Q","Jacobi, Anthony M.","Glumac, Nick G.","Riemer, Nicole"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-09-04T20:46:47Z","date_published":"2018-09-04T20:46:47Z","updated_at":"2026-07-22T22:24:38Z","subjects":["Water droplets, Radiation, Evaporation, Condensation, Clouds"],"languages":["en"],"rights":["Copyright 2018 Kibria Roman"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/101255","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Brewster, M Q","Jacobi, Anthony M.","Glumac, Nick G.","Riemer, Nicole"]},{"key":"dc:creator","label":"Author","values":["Roman, Kibria Khan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-09-04T20:46:47Z","2018-02-12","2018-05"]},{"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":["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":["Water droplets, Radiation, Evaporation, Condensation, Clouds"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2018 Kibria Roman"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/101255"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The effect of thermal radiation on cloud droplet evolution was investigated both experimentally and theoretically. Droplet size measurements were conducted on laminar, saturated water mist flowing through a tube apparatus with an inner wall cooled to induce radiative heat transfer from the mist droplets to the tube wall. The flow tube was designed to isolate the radiative effect by eliminating convective heat transfer between the mist flow and the chamber wall. Droplet size distributions were measured before and after radiative cooling using a light scattering optical analyzer. Radiative flux varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section varied from 15 to 60 seconds. Droplet sizes increased significantly after they underwent radiative cooling. For example, with 145 W/m2 radiative flux, the volume-average size (D43) increased from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section. Thus, experimental evidence was obtained that demonstrated that droplet radiation to a remote, cold radiative sink can augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime. The droplet size distributions measured were fit with Weibull, Gaussian, and Lorentzian distribution functions, and the Gaussian distribution fit best. The results demonstrated that the radiatively induced condensation process transformed droplet spectra from monomodal to bimodal, in accordance with theoretical predictions. These bimodal droplet distributions were found to be skewed positively, with relatively wide dispersions for the smaller mode and less dispersion for the larger mode. Theoretical results were compared with droplet size distributions measured before and after radiative cooling, for radiative flux that varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section that ranged from 15 to 60 seconds. Calculations confirmed the experimental observations that droplet sizes increased significantly after experiencing radiative cooling. For example, with 145 W/m2 radiative flux (245 K wall temperature), calculations predicted a volume-average size (D43) increase from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section, which was consistent with measurements. With respect to size distribution data, calculations showed partial or qualitative agreement, but not complete quantitative agreement, in that the calculations matched the experimental size distribution data reasonably well only for droplets larger than 100 µm, indicating the need for further improvement in modeling assumptions. Thus, theoretical support was demonstrated for the concept that droplet radiation to a remote, cold radiative sink might augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-05-01","The student, Kibria Roman, accepted the attached license on 2018-02-08 at 22:03.","The student, Kibria Roman, submitted this Dissertation for approval on 2018-02-08 at 22:04.","This Dissertation was approved for publication on 2018-02-12 at 10:10.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12035 on 2018-08-31 at 17:25:02","Made available in DSpace on 2018-09-04T20:46:47Z (GMT). No. of bitstreams: 2 ROMAN-DISSERTATION-2018.pdf: 2997335 bytes, checksum: c92d59689e980817fa1196cb7054849a (MD5) LICENSE.txt: 4209 bytes, checksum: 9532ecce4bccaca4049fe42e4e9de43c (MD5) Previous issue date: 2018-02-12","Embargo set by: Seth Robbins for item 107340 Lift date: 2020-09-04T20:47:38Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 107340 Lift date: 2020-09-04T20:50:11Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Open Restriction set for Item 107340 on 2018-09-28T14:06:41Z with date null by fschaef2@illinois.edu.","Open Restriction set for Item 107340 on 2018-09-28T14:06:43Z with date null by fschaef2@illinois.edu.","Open"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Radiative impacts on water mist/cloud droplet condensative growth"]}]}],"canonical_facts":{"dc:contributor":["Brewster, M Q","Jacobi, Anthony M.","Glumac, Nick G.","Riemer, Nicole"],"dc:creator":["Roman, Kibria Khan"],"dc:date":["2018-09-04T20:46:47Z","2018-02-12","2018-05"],"dc:description":["The effect of thermal radiation on cloud droplet evolution was investigated both experimentally and theoretically. Droplet size measurements were conducted on laminar, saturated water mist flowing through a tube apparatus with an inner wall cooled to induce radiative heat transfer from the mist droplets to the tube wall. The flow tube was designed to isolate the radiative effect by eliminating convective heat transfer between the mist flow and the chamber wall. Droplet size distributions were measured before and after radiative cooling using a light scattering optical analyzer. Radiative flux varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section varied from 15 to 60 seconds. Droplet sizes increased significantly after they underwent radiative cooling. For example, with 145 W/m2 radiative flux, the volume-average size (D43) increased from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section. Thus, experimental evidence was obtained that demonstrated that droplet radiation to a remote, cold radiative sink can augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime. The droplet size distributions measured were fit with Weibull, Gaussian, and Lorentzian distribution functions, and the Gaussian distribution fit best. The results demonstrated that the radiatively induced condensation process transformed droplet spectra from monomodal to bimodal, in accordance with theoretical predictions. These bimodal droplet distributions were found to be skewed positively, with relatively wide dispersions for the smaller mode and less dispersion for the larger mode. Theoretical results were compared with droplet size distributions measured before and after radiative cooling, for radiative flux that varied from 85 to 184 W/m2 and minimum (centerline) droplet residence time in the radiative section that ranged from 15 to 60 seconds. Calculations confirmed the experimental observations that droplet sizes increased significantly after experiencing radiative cooling. For example, with 145 W/m2 radiative flux (245 K wall temperature), calculations predicted a volume-average size (D43) increase from 29 to 39 µm after approximately 60 seconds of (minimum) centerline residence time in the radiative cooling section, which was consistent with measurements. With respect to size distribution data, calculations showed partial or qualitative agreement, but not complete quantitative agreement, in that the calculations matched the experimental size distribution data reasonably well only for droplets larger than 100 µm, indicating the need for further improvement in modeling assumptions. Thus, theoretical support was demonstrated for the concept that droplet radiation to a remote, cold radiative sink might augment droplet growth significantly in the 20 to 80 µm condensation-coalescence bottleneck regime.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-05-01","The student, Kibria Roman, accepted the attached license on 2018-02-08 at 22:03.","The student, Kibria Roman, submitted this Dissertation for approval on 2018-02-08 at 22:04.","This Dissertation was approved for publication on 2018-02-12 at 10:10.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12035 on 2018-08-31 at 17:25:02","Made available in DSpace on 2018-09-04T20:46:47Z (GMT). No. of bitstreams: 2 ROMAN-DISSERTATION-2018.pdf: 2997335 bytes, checksum: c92d59689e980817fa1196cb7054849a (MD5) LICENSE.txt: 4209 bytes, checksum: 9532ecce4bccaca4049fe42e4e9de43c (MD5) Previous issue date: 2018-02-12","Embargo set by: Seth Robbins for item 107340 Lift date: 2020-09-04T20:47:38Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 107340 Lift date: 2020-09-04T20:50:11Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Open Restriction set for Item 107340 on 2018-09-28T14:06:41Z with date null by fschaef2@illinois.edu.","Open Restriction set for Item 107340 on 2018-09-28T14:06:43Z with date null by fschaef2@illinois.edu.","Open"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/101255"],"dc:language":["en"],"dc:rights":["Copyright 2018 Kibria Roman"],"dc:subject":["Water droplets, Radiation, Evaporation, Condensation, Clouds"],"dc:title":["Radiative impacts on water mist/cloud droplet condensative growth"],"dc:type":["text"],"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":"2026-07-22T22:24:38Z"}