Improved startup performance of a dual compensation chamber loop heat pipe by sequential cooling to the compensation chambers

Dual compensation chamber loop heat pipe (DCCLHP) holds great application potential in efficient heat dissipation of avionics due to its flexible heat transport, fast temperature response, and effective liquid replenishment in all orientations. In this work, a DCCLHP with sequential cooling to the compensation chambers (CCs) was proposed, aiming to enhance its startup performance especially under unfavorable attitudes. Comprehensive experimental studies were conducted mainly focusing on its startup performance with the evaporator/CCs under five typical attitudes. Experimental results show that the DCCLHP could provide effective cooling to the CCs, enabling the DCCLHP to realize successful startup under small heat loads of 0–100 W in all orientations, and no startup failure occurred. For the startup under 80 W at -90° tilt angle, it took only 13 s from applying heat load to the evaporator to the vapor's entering the condenser, and the lowest system thermal resistance was only 0.193 °C/W. The heat load taken away by the wrapping line from the CC1 was also quantitatively analyzed based on the energy balance of the CC1. The wrapping line under unfavorable attitudes effectively takes more heat load away from the CC1. In the startup under 100 W at -45°, the heat load taken away by the wrapping line reached a maximum of 3.71 W. This work well demonstrates that the DCCLHP can achieve orientation-free startup in attitude-varying application scenarios.