Effect of Shape and Orientation of Flat Heat Pipe on Its Thermal Performance

Flat heat pipes (FHPs) are employed in various industries and applications where efficient heat transfer is required to maintain the operation and reliability of the system such as electronics cooling, aerospace, medical devices, etc. The impact of the shape of flat heat pipes (FHPs) on the effective thermal conductivity of FHP has been experimentally investigated in the present work. The copper-based FHPs were charged with DI water, and a single layer of 100 mesh screen was employed as a wick structure. The FHP was 0.2 m in length, 0.01 m in width, and 0.003 m thick. The four different geometries such as horizontal, L-shaped (3 different orientations), stair-step-shaped, and U-shaped of FHPs were considered. The FHPs’ functioning was evaluated in terms of effective thermal conductivity at different heat levels for fan-assisted forced convection and free convection condenser cooling. The shape and orientation of the FHP affect its thermal behavior in addition to physical and operational qualities. Among all testing runs, the L-shaped FHP with gravity-assisted (condenser at top and in vertical plane and evaporator at bottom and in horizontal plane) configuration at 12-W heat load and free convection condenser cooling achieved the optimum effective thermal conductivity of 9756 W/mK. Comparing all other shapes, the thermal operation of the L-shaped FHP with this configuration was found best for both fan-aided forced convection and free convection condenser cooling.