Design and experimental study of a dual compensation chamber flat loop heat pipe for electronic devices

Abstract

In this article, a novel flat loop heat pipe with dual compensation chamber was designed and manufactured to address the heat dissipation challenges of high-power electronic devices operating in various orientations. Ammonia was selected as the working fluid, with stainless steel used for the casing material. The capillary wick consisted of a combination of a wire mesh and a sintered nickel wick. A theoretical analysis was performed based on the distribution of the working fluid in the two compensation chambers, identifying three possible thermodynamic processes for the flat loop heat pipe. The startup and heat transfer performance were experimentally evaluated under six different orientations and varying heat sink temperatures. Experimental results indicated that: (1) the flat loop heat pipe successfully starts and reaches a steady state at 100 W in all orientations, with gravity influencing the startup process by altering the working fluid distribution in the two compensation chambers; (2) at a heat sink temperature of 20 °C, the maximum heat transfer capacity reaches 500 W, while the minimum thermal resistance is 0.059 °C/W at 450 W; (3) when the heat load exceeds 250 W, the impact of orientation on operating temperature and thermal resistance becomes negligible; and (4) the flat loop heat pipe has excellent transient response performance under varying heat loads. These finding provide valuable insights for the application of flat loop heat pipes in avionics devices with complex and variable orientations.