Date of Defense
5-11-2025 11:30 AM
Location
F1-1164
Document Type
Thesis Defense
Degree Name
Master of Science in Mechanical Engineering (MSME)
College
COE
Department
Mechanical and Aerospace Engineering
First Advisor
Prof. Emad Elnajjar
Abstract
The RanqueβHilsch vortex tube (RHVT) is a passive thermos-fluid device that splits compressed gas into simultaneous cold and hot streams through strong swirling flow inside a slender tube, without moving parts. This study experimentally examines how external boundary conditions applied to the tube wall influence RHVT performance. Three wall conditions were imposed: (i) externally cooled (cooling), (ii) externally heated (heating), and (iii) adiabatic (insulated). Tests were conducted with air over an inlet pressure range of 2β6 bar. The primary objective was to understand the extent to which wall thermal condition modifies temperature separation and energy efficiency. Performance was quantified using the refrigeration coefficient of performance (πΆπππ), together with measurements of cold-end and hot-end air flow stream temperatures. Compared with the baseline unconditioned case, externally cooling the wall consistently produced the lowest cold-end temperatures across all pressures and the highest refrigeration performance. At a tube wall setpoint of 25 Β°C, the refrigeration coefficient of performance (πΆπππ) improved by ~89% on average over 2β6 bar, with the maximum average gain at 4 bar (~109%); gains increased monotonically as the wall setpoint was reduced from 45 to 25 Β°C. Insulation yielded a slight but robust uplift (mean +4.24% in πΆπππ across 2β6 bar, peaking at +5.3% at 3 bar). By contrast, heating the wall reduced temperature separation and depressed πΆπππ, with penalties that grew with the tube wall temperature setpoint. These findings highlight the sensitivity of RHVT behavior to heat transfer at the wall and suggest that controlled external cooling can be an effective lever for improving cold-stream performance in practical applications. The results provide guidance for the design and operation of vortex-tube-based spot cooling and process temperature control, and they motivate further work to resolve optimal combinations of pressure, cold mass fraction, and wall condition under various operating parameters.
Included in
EXPERIMENTAL INVESTIGATION: PERFORMANCE OF RANQUE-HILSCH VORTEX TUBES UNDER VARIOUS SURFACE BOUNDARY CONDITIONS
F1-1164
The RanqueβHilsch vortex tube (RHVT) is a passive thermos-fluid device that splits compressed gas into simultaneous cold and hot streams through strong swirling flow inside a slender tube, without moving parts. This study experimentally examines how external boundary conditions applied to the tube wall influence RHVT performance. Three wall conditions were imposed: (i) externally cooled (cooling), (ii) externally heated (heating), and (iii) adiabatic (insulated). Tests were conducted with air over an inlet pressure range of 2β6 bar. The primary objective was to understand the extent to which wall thermal condition modifies temperature separation and energy efficiency. Performance was quantified using the refrigeration coefficient of performance (πΆπππ), together with measurements of cold-end and hot-end air flow stream temperatures. Compared with the baseline unconditioned case, externally cooling the wall consistently produced the lowest cold-end temperatures across all pressures and the highest refrigeration performance. At a tube wall setpoint of 25 Β°C, the refrigeration coefficient of performance (πΆπππ) improved by ~89% on average over 2β6 bar, with the maximum average gain at 4 bar (~109%); gains increased monotonically as the wall setpoint was reduced from 45 to 25 Β°C. Insulation yielded a slight but robust uplift (mean +4.24% in πΆπππ across 2β6 bar, peaking at +5.3% at 3 bar). By contrast, heating the wall reduced temperature separation and depressed πΆπππ, with penalties that grew with the tube wall temperature setpoint. These findings highlight the sensitivity of RHVT behavior to heat transfer at the wall and suggest that controlled external cooling can be an effective lever for improving cold-stream performance in practical applications. The results provide guidance for the design and operation of vortex-tube-based spot cooling and process temperature control, and they motivate further work to resolve optimal combinations of pressure, cold mass fraction, and wall condition under various operating parameters.