Experimental investigations on novel orientation study on axially grooved heat pipe with two evaporators and one condenser with multiple branches

Conventional heat pipes with one evaporator and one condenser are used to cool only one heat source at a time. In electronics and space applications, where a large number of heat sources are to be cooled with limited space available, a multi branch heat pipe could be the solution. In the present study, a heat pipe (T-shape) with three branches was developed with 20 number of axial grooves in which two branches worked as evaporators and one branch as a condenser. Experimental study was performed by considering four novel types of orientations i.e. (a) horizontal orientation (HO) (b) gravity assisted orientation (GAO) (c) anti-gravity orientation (AGO) and (d) compound orientation (CO). The results are analyzed in terms of start-up characteristics and total heat transfer coefficient at different heat loads. Evaporator and condenser thermal resistances are calculated and analyzed for better understanding. It was found that horizontal orientation resulted in the highest overall heat transfer coefficient (2.72 kW/m² ℃ at 240 W) and comparatively lower evaporator temperatures (less than 100 ℃ at 240 W) which is suitable condition for electronics cooling. Maximum effective thermal conductivity of 31.82 kW/m ℃ was achieved in horizontal orientation. It also resulted in lowest evaporator resistance (0.157 ℃/W) and lowest condenser resistance (0.114 ℃/W). Phenomena of temperature jump was observed and elaborated for compound orientation.