Effect of confluence length on the heat transport capability of ultra-thin multiport minichannel thermosyphon

• Published in: Applied thermal engineering 2022-01, Vol.201, p.117763, Article 117763
• Main Authors: Manova, Stephen, Godson Asirvatham, Lazarus, Raja Bose, Jefferson, Tharayil, Trijo, Wongwises, Somchai
• Format: Article
• Language: English
• Subjects: Acetone; Confluence length; Entrainment; Evaporators; Flat thermosyphon; Heat conductivity; Heat exchangers; Heat transfer; Heat transfer coefficients; Heat transport limit; Hydraulics; Inclination angle; Multiports; Rectangular mini channel; Surface tension; Temperature; Thermal resistance; Thermosyphons; Thin films; Wall temperature; Working fluids
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2021.117763

•Multi-ports act as internal fins & increases surface area and evaporation rate.•Optimum Confluence length (Colen) dissipated 90 W at vertical orientation IA = 90°.•42.4% decrease in thermal resistance was observed at optimum Colen = 5 mm.•18.3% reduction in evaporator wall temperature was noted for optimum Colen.•19.5% increase in evaporator heat transfer coefficient noted for optimum Colen. Effect of confluence lengths (Colen = 0 mm, 5 mm and 10 mm), heat loads (10–90 W), filling ratios (FR = 40% to 60%) and inclination angles (IA = 30°, 45°, 60°and 90°) on the heat transport capability of a multiport minichannel (MPMC) thermosyphon with hydraulic diameter of 1.18 mm and having Acetone as the working fluid is experimentally investigated. Enhancement of 33% in the heat transport capability (up to 90 W) was observed for MPMC thermosyphon with optimumColen = 5 mm, whereas it was only 60 W atColen = 0 mm. Reduction of 42.4% and 18.3% in thermal resistance (Rt) and evaporator wall temperature (Te,w) and enhancement of 19.5% in evaporator heat transfer coefficient (heva) are respectively observed for MPMC thermosyphon with optimumColen = 5 mm and inclination angle (IA = 90°) when compared withColen = 0 mm. Combination of reduced entrainment effect causing faster circulation of working fluid at optimumColen, surface tension effect which pulls the bulk condensate to the corners and the thin film at flat sides of multiports are found to be the major reasons for enhancement in the heat transport capability of MPMC thermosyphon.