Thermal management performance of a novel elliptically grooved flat heat pipe system embedded with internally cooled condenser

• Thermal resistance decreased by 27.8 % with 0.7 mm depth elliptical grooves. • Elliptical grooves in heat pipe reduces non-evaporative zones near evaporator. • Evaporator wall temperature reduced by 6.5 % with using 0.7 mm elliptical grooves. Flat heat pipes (FHPs) with rectangular groove wick structures fail to sufficiently uplift the working fluid’s liquid meniscus to cover the upper sides of the groove walls due to the vertically flat wall design. This results in the formation of non-evaporative zones, particularly in the evaporator region, leading to elevated wall temperatures at high heat loads. To address this issue, a novel FHP with elliptical grooves as wick is designed and tested across heat loads ranging from 30 to 360 W. Elliptical groove depths of 0.5 mm and 0.7 mm are evaluated and compared to FHPs with rectangular grooves. Results showed that at 360 W, the 0.7 mm depth elliptical grooves resulted in 6.5 % reduction in evaporator wall temperature and 27.8 % reduction in thermal resistance, along with 31.5 % enhancement in effective thermal conductivity compared to rectangular grooves. The curvature of the elliptical grooves, combined with enhanced surface tension effects of the working fluid, efficiently uplifted the liquid meniscus to cover the upper wall of the groove, minimizing non-evaporative zones. Additionally, FHPs with elliptical grooves demonstrated lower entropy generation, indicating higher thermal efficiency. Consequently, FHPs with elliptical groove designs are concluded to be an efficient and suitable solution for the thermal management of miniaturized electronic devices.