Author ORCID Identifier:
Date of Graduation
7-2026
Document Type
Thesis
Degree Name
Master of Science in Mechanical Engineering (MSME)
Degree Level
Graduate
Department
Mechanical Engineering
Advisor/Mentor
Hu, Han
Committee Member
Huitink, David
Second Committee Member
Walters, Keith
Keywords
Boiling Hysteresis; Electronics Cooling; Pool Boiling; Subatmospheric Pressure; Thermal Engineering
Abstract
The increasing power density of microelectronics has created a need for cooling technologies capable of maintaining low operating temperatures. Sub-atmospheric pool boiling of water is promising because reducing saturation pressure lowers the boiling temperature, enabling two phase cooling within electronics-relevant temperature limits. However, reduced pressure also affects CHF, HTC, and post-CHF recovery. In this work, pool boiling experiments were conducted on flat copper, microchannel copper, and micro-pin-fin copper surfaces over 10–100 kPa to examine the coupled effects of pressure and surface structure. CHF and HTC increased with pressure, while structured surfaces enhanced both relative to flat copper. Surface structure dominated CHF enhancement, with structured surfaces at 10 kPa exceeding the CHF of flat copper near atmospheric pressure, whereas HTC depended on both pressure and surface structure. Post-CHF analysis showed that boiling hysteresis was reduced at lower pressures, especially from 10–30 kPa, allowing faster recovery to nucleate boiling. The hysteresis ratio, �� =��"NBR/��"CHF, collapsed with maximum post-CHF wall superheat, indicating that recovery is governed by the thermal maturity of the CHF-generated vapor/dry state. High-speed imaging and BubbleID segmentation supported this interpretation by showing vapor persistence and rewetting. Overall, sub-atmospheric pressure operation combined with surface micro-structuring provides a viable pathway for high-performance water-based cooling of high-power-density electronics.
Citation
Hossain, M. (2026). Coupled Effects of Sub-Atmospheric Pressure and Surface Structures on Pool Boiling Performance and Hysteresis Pathways. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/6412
