{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/132702"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/132702","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Exploring water-in-oil emulsions for immersion cooling: thermophysical properties, electrical insulation, and chip-level performance","abstract":"This thesis experimentally evaluates Span 80–stabilized water-in-oil (W/O) emulsions, prepared from Crystal Plus Oil 70T with 2.5–20 vol% water, as immersion coolants for natural-convection cooling of high-power electronics. Conventional dielectric oils provide good insulation but low thermal conductivity, which limits chip-level heat dissipation. A property-based figure of merit for natural convection is derived to assess how density, heat capacity, thermal conductivity, thermal expansion, and viscosity jointly affect performance, and is used to guide emulsion formulation. The fluids are characterized by dynamic light scattering, rheometry, thermal-conductivity measurements, and high-voltage DC leakage tests up to 550 V, followed by chip-level immersion-cooling experiments on an Infineon MOSFET module. For water contents up to 10 vol%, leakage currents remain within the range of commercial dielectric fluids, whereas 20 vol% causes a sharp rise in leakage. Water addition increases thermal conductivity by ~10–30% but also raises viscosity by up to several-fold, making viscosity the dominant constraint. Chip-level results show that 2.5 vol% water reduces minimum thermal resistance from ~6.75 to 5.07 K/W and increases maximum sustainable power from ≈18.3 to ≈24.2 W. Thus, low-water W/O emulsions (≈2.5–5 vol%) are promising immersion coolants that partially relax the trade-off between thermal and electrical performance.","abstract_html":"This thesis experimentally evaluates Span 80–stabilized water-in-oil (W/O) emulsions, prepared from Crystal Plus Oil 70T with 2.5–20 vol% water, as immersion coolants for natural-convection cooling of high-power electronics. Conventional dielectric oils provide good insulation but low thermal conductivity, which limits chip-level heat dissipation. A property-based figure of merit for natural convection is derived to assess how density, heat capacity, thermal conductivity, thermal expansion, and viscosity jointly affect performance, and is used to guide emulsion formulation. The fluids are characterized by dynamic light scattering, rheometry, thermal-conductivity measurements, and high-voltage DC leakage tests up to 550 V, followed by chip-level immersion-cooling experiments on an Infineon MOSFET module. For water contents up to 10 vol%, leakage currents remain within the range of commercial dielectric fluids, whereas 20 vol% causes a sharp rise in leakage. Water addition increases thermal conductivity by ~10–30% but also raises viscosity by up to several-fold, making viscosity the dominant constraint. Chip-level results show that 2.5 vol% water reduces minimum thermal resistance from ~6.75 to 5.07 K/W and increases maximum sustainable power from ≈18.3 to ≈24.2 W. Thus, low-water W/O emulsions (≈2.5–5 vol%) are promising immersion coolants that partially relax the trade-off between thermal and electrical performance.","abstract_has_math":false,"creators":["Yang, Haoshen"],"institution":"University of Illinois Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Miljkovic, Nenad"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-12","date_published":"2025-12","updated_at":"2026-07-22T22:25:07Z","subjects":["water-in-oil emulsion","immersion cooling","natural convection","dielectric coolant","power electronics","subcooled boiling"],"languages":["en"],"rights":["Copyright 2025 Haoshen Yang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/132702","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Miljkovic, Nenad"]},{"key":"dc:creator","label":"Author","values":["Yang, Haoshen"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-12","2025-12-11"]},{"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":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["water-in-oil emulsion","immersion cooling","natural convection","dielectric coolant","power electronics","subcooled boiling"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Haoshen Yang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/132702"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This thesis experimentally evaluates Span 80–stabilized water-in-oil (W/O) emulsions, prepared from Crystal Plus Oil 70T with 2.5–20 vol% water, as immersion coolants for natural-convection cooling of high-power electronics. Conventional dielectric oils provide good insulation but low thermal conductivity, which limits chip-level heat dissipation. A property-based figure of merit for natural convection is derived to assess how density, heat capacity, thermal conductivity, thermal expansion, and viscosity jointly affect performance, and is used to guide emulsion formulation. The fluids are characterized by dynamic light scattering, rheometry, thermal-conductivity measurements, and high-voltage DC leakage tests up to 550 V, followed by chip-level immersion-cooling experiments on an Infineon MOSFET module. For water contents up to 10 vol%, leakage currents remain within the range of commercial dielectric fluids, whereas 20 vol% causes a sharp rise in leakage. Water addition increases thermal conductivity by ~10–30% but also raises viscosity by up to several-fold, making viscosity the dominant constraint. Chip-level results show that 2.5 vol% water reduces minimum thermal resistance from ~6.75 to 5.07 K/W and increases maximum sustainable power from ≈18.3 to ≈24.2 W. Thus, low-water W/O emulsions (≈2.5–5 vol%) are promising immersion coolants that partially relax the trade-off between thermal and electrical performance.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01","The student, Haoshen Yang, accepted the attached license on 2025-12-09 at 11:09.","The student, Haoshen Yang, submitted this Thesis for approval on 2025-12-09 at 11:17.","This Thesis was approved for publication on 2025-12-11 at 13:33.","DSpace SAF Submission Ingestion Package generated from Vireo submission #23111 on 2026-02-19 at 18:46:53"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Exploring water-in-oil emulsions for immersion cooling: thermophysical properties, electrical insulation, and chip-level performance"]}]}],"canonical_facts":{"dc:contributor":["Miljkovic, Nenad"],"dc:creator":["Yang, Haoshen"],"dc:date":["2025-12","2025-12-11"],"dc:description":["This thesis experimentally evaluates Span 80–stabilized water-in-oil (W/O) emulsions, prepared from Crystal Plus Oil 70T with 2.5–20 vol% water, as immersion coolants for natural-convection cooling of high-power electronics. Conventional dielectric oils provide good insulation but low thermal conductivity, which limits chip-level heat dissipation. A property-based figure of merit for natural convection is derived to assess how density, heat capacity, thermal conductivity, thermal expansion, and viscosity jointly affect performance, and is used to guide emulsion formulation. The fluids are characterized by dynamic light scattering, rheometry, thermal-conductivity measurements, and high-voltage DC leakage tests up to 550 V, followed by chip-level immersion-cooling experiments on an Infineon MOSFET module. For water contents up to 10 vol%, leakage currents remain within the range of commercial dielectric fluids, whereas 20 vol% causes a sharp rise in leakage. Water addition increases thermal conductivity by ~10–30% but also raises viscosity by up to several-fold, making viscosity the dominant constraint. Chip-level results show that 2.5 vol% water reduces minimum thermal resistance from ~6.75 to 5.07 K/W and increases maximum sustainable power from ≈18.3 to ≈24.2 W. Thus, low-water W/O emulsions (≈2.5–5 vol%) are promising immersion coolants that partially relax the trade-off between thermal and electrical performance.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01","The student, Haoshen Yang, accepted the attached license on 2025-12-09 at 11:09.","The student, Haoshen Yang, submitted this Thesis for approval on 2025-12-09 at 11:17.","This Thesis was approved for publication on 2025-12-11 at 13:33.","DSpace SAF Submission Ingestion Package generated from Vireo submission #23111 on 2026-02-19 at 18:46:53"],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/132702"],"dc:language":["en"],"dc:rights":["Copyright 2025 Haoshen Yang"],"dc:subject":["water-in-oil emulsion","immersion cooling","natural convection","dielectric coolant","power electronics","subcooled boiling"],"dc:title":["Exploring water-in-oil emulsions for immersion cooling: thermophysical properties, electrical insulation, and chip-level performance"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:07Z"}