Experimental study on steady-state performance of an axial grooved heat pipe under rotational condition

This study investigates the operating characteristics of an axial grooved heat pipe (AGHP) under rotational conditions, with the aim of enhancing satellite cooling performance in such environments. Two sets of Ω-shaped aluminum-ammonia AGHPs with different structural designs were fabricated and tested under various rotational angular velocities, heating loads, and loading methods. The curved grooved heat pipe, designed to mitigate the adverse effects of centrifugal force, demonstrated significant advantages over the straight grooved heat pipe. Experimental results showed that: (i) during steady-state operation under rotational conditions, the straight grooved heat pipe is influenced by centrifugal force, causing the working fluid to accumulate at both ends. This reduces the effective heat transfer distance and increases the overall operating temperature. At a rotational velocity of 120°/s and a heating power of 110 W, the temperature difference exceeds 25°C, indicating inefficiency in rotational
environments. (ii) the adiabatic and condenser sections of the curved grooved heat pipe are designed in a circular shape centered around the rotational axis to minimize the effects of centrifugal force. This design eliminates liquid plugs in the condenser section under rotational conditions, as the centrifugal force component in the flow direction is zero when perpendicular. (iii) the curved grooved heat pipe benefits from centrifugal force in the evaporator section, aiding fluid return. This enhances the heat transfer limit, reduces thermal resistance, and improves temperature uniformity. At a rotational velocity of 120°/s, the curved AGHP effectively transfers over 300 W with a temperature difference not exceeding 5°C. (iv) at high rotational velocities and low power conditions, the centrifugal force-driven return of the working fluid can lead to excessive accumulation in the evaporator section. This may cause a shift from film boiling to pool boiling, introducing superheat and raising the evaporator's operating temperature.