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

Effect of confluence lengths (Co_len = 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 optimum Co_len = 5 mm, whereas it was only 60 W at Co_len = 0 mm. Reduction of 42.4% and 18.3% in thermal resistance (R_t) and evaporator wall temperature (T_e,w) and enhancement of 19.5% in evaporator heat transfer coefficient (h_eva) are respectively observed for MPMC thermosyphon with optimum Co_len = 5 mm and inclination angle (IA = 90°) when compared with Co_len = 0 mm. Combination of reduced entrainment effect causing faster circulation of working fluid at optimum Co_len, 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.