Experimental study on the operating performance of a novel flat loop heat pipe with liquid channels under terrestrial and accelerated conditions

To address the cooling challenges of future advanced airborne electronic equipment, in this article, a dual compensation chamber stainless steel-ammonia flat loop heat pipe (FLHP) with liquid channels was designed and fabricated. A test rig was set up to evaluate the startup and operating performance under two typical acceleration directions and terrestrial conditions. In the current study, acceleration is defined as direction Ⅰ when it is directed from CC2 to CC1, and as direction Ⅱ is when it oriented from the evaporator to the condenser. Experimental results indicated that: (i) under terrestrial conditions, the FLHP can successfully start at 10 W and quickly reach steady state under varying heat loads (10 ∼ 500 W). (ii) the FLHP successfully started and reached a steady state under 6 g acceleration in both directions, but the time required to reach steady state is longer than that under terrestrial conditions. (iii) the steady-state operating temperature versus heat load shows a “V” shaped curve under both terrestrial and acceleration conditions. The transitions from the variable to the constant conductance model occur at heat loads of 200 W, 400 W, and 300 W for terrestrial condition, acceleration direction Ⅰ, and acceleration direction Ⅱ, respectively. (iv) accelerations in both directions increase the FLHP operating temperature. In direction Ⅰ, acceleration mainly affects the fluid distribution between the CCs, altering heat leakage from the evaporator. In direction II, it primarily increases the flow resistance in the external loop. The findings of this study provide strong support for the thermal management of electronic devices, especially offering broad application prospects in complex and variable airborne acceleration environments.